PRL internship

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PAKISTAN REFINERY LIMITED
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  • 1. INDUSTRIAL TRAINING REPORT OF FOUR WEEKS INTERNSHIP AT PAKISTAN REFINERY LIMITED KARACHI Submitted to: INTERNSHIP SUPERVISOR ENGR. AQEEL AHMED BAZMI Assistant Professor (For Partial Fulfilment of Summer Semester Industrial Training of 3 Credit Hours) Submitted by: MODUSSER TUFAIL CIIT/FA05-BEC-006/LHR ABDUL BASIT CIIT/FA05-BEC-025/LHR KHAQAN JAVED CIIT/FA05-BEC-029/LHR Date of Submission: October 7, 2008 Department of Chemical Engineering COMSATS Institute of Information Technology Defence Road Off Raiwind Road Lahore
  • 2. 2 Dedicated to Our Mentor Engr. Aqeel Ahmed Bazmi
  • 3. 3 UCERTIFICATE This is to certify that work presented in Industrial Training Report of 4 weeks Internship at Pakistan Refinery Limited is entirely written by following students themselves under the supervision of Engr. Aqeel Ahmed Bazmi: 1. MODUSSER TUFAIL CIIT/FA05-BEC-006/LHR 2. ABDUL BASIT CIIT/FA05-BEC-025/LHR 3. KHAQAN JAVED CIIT/FA05-BEC-029/LHR ______________________ Engr. Aqeel Ahmed Bazmi Internship Supervisor ______________________ Dr. Moinuddin Ghauri HOD Department of Chemical Engineering Date: ____________
  • 4. 4 PREFACE This report is about the learning outcomes of internship in Pakistan Refinery Limited (PRL) Karachi covering details of its environment, process, operations and other technical information. There is a datasheet maintained in every department giving a complete picture of activities and updated every 2 or 4 hours depending upon the nature of the processes and operations taking place. Most of the Information was collected from datasheet of every department and is written according to internship schedule provided by PRL. This helps to understand various steps involved in achieving certain efficiency or the quality of the product. Undoubtedly there is so much to learn from this industry and this is a small effort to compile as much information that have been collected in four weeks span. A learning session at DAWOOD Engineering College Karachi is also covered in this report wherein some ASTM tests are mentioned (used for the fuel specification) and liquid-liquid extraction experiment for mass transfer understanding. Lists of Tables and Figures are mentioned covering the operating conditions of various sections for illustration of data.
  • 5. 5 ACKNOWLEDGEMENT In our Department we would like to acknowledge; our Head of Department (HOD) Dr. Moinuddin Ghauri, our Industrial Liaison Officer Mr. Abrar Inayat for 18 different industrial visits, especially Internship Supervisor Engr. Aqeel Ahmed Bazmi who made all the arrangements of our trip to Karachi and Internship including the special attention we got from his DCETIAN students in PRL helping us grow in a professional manner, and all the subject teachers who dedicatedly and devotedly equipped us with chemical engineering toolbox. We would like to acknowledge Dr. Amjad Hussain Dilawari, (EX-HOD Department of Chemical Engineering), Dr. Asad Javed, and Engr. Zeeshan Ahuja who in their tenures created a driving force in our life which is still helping us completing the education and excel professionally. We are thankful to PRL which provided us a chance to integrate our classroom knowledge with industrial practical knowledge in 4 weeks internship program. We are grateful to Mr. Tariq Masood who helped us in internship program remaining closely in contact to make sure we are right on the track, Mr. Abid Hussain for monitoring our learning and helping us understand the process in numerous interactions we were honored, Mr. Ismail Bhatti for answering our technical queries, Mr. Adnan for helping us understand nature of products, related calculations and coding used in the plant, Mr. Fawad Raza, for Health, Safety and Environment awareness, Mr. Abdul Rasheed in orientation with Laboratory equipment, Mr. Shehzad for helping us in Research Octane Number Calculation, Mr. Akram Paracha (for his special concern in learning of students) and those Graduate Training Engineers (GTE) namely Mr. Saddar-ud- Din, Mr. Israr-ul-Haq, Mr. Badar-ud-din, Mr. Inam-ul-haq, … who never felt bothered by our queries instead always helped us in getting the answers. We would like to thank Prof. Nisar Ahmed Pathan Chairman Department of Chemical Engineering Dawood College of Engineering and Technology (DCET), Engr. Abdul Waheed Bhutto (Assistant Professor) for helping us throughout our session in DCET,
  • 6. 6 Dr. Damani from University of Karachi for methods of ASTM tests conducted for Post Graduate Students of Applied Chemistry. We would like to acknowledge our families who are fully supporting us to continue our educational activities for our better Prospects.
  • 7. 7 TABLE OF CONTENTS TUPREFACEUT .....................................................................................................................4 TUACKNOWLEDGEMENTUT .............................................................................................5 TULIST OF TABLESUT ........................................................................................................8 TULIST OF FIGURESUT ......................................................................................................8 TUSCHEDULE OF OVERALL ACTIVITIESUT.................................................................9 TUEXECUTIVE SUMMARYUT ..........................................................................................10 TU1.UT TUCOMPANY PROFILEUT ........................................................................................13 TU2.UT TUHSEQ ORIENTATIONUT ......................................................................................17 TU3.UT TUOIL MOVEMENTUT ..............................................................................................19 TU4.UT TUUTILITIESUT ..........................................................................................................23 TU5.UT TUBOILERSUT ............................................................................................................27 TU6.UT TUWASTE WATER TREATMENT PLANTUT ..........................................................29 TU7.UT TUPUMPS AND SAMPLESUT ...................................................................................34 TU8.UT TULABORATORYUT ...................................................................................................35 TU9.UT TUCOMPRESSORSUT ................................................................................................39 TU10.UT TUGENERATORSUT ...............................................................................................41 TU11.UT TUFURNACESUT ....................................................................................................42 TU12.UT TUCRUDE / PLATUT ...............................................................................................43 TU13.UT TUMISCELLANEOUSUT ........................................................................................57 TUSUGGESTIONSUT ..........................................................................................................60 TULEARNING EXPERIENCE AT D.C.E.T. KARACHIUT..............................................61 TUPHOTOGALLERY:UT ....................................................................................................65 TUAPPENDIXUT .................................................................................................................68
  • 8. 8 LIST OF TABLES TUTable 1: Shareholders of PRLUT ......................................................................................13 TUTable 2: Production of Year 2007-2008UT ......................................................................13 TUTable 3: Grades of Crude Oil used in PRLUT ..................................................................19 TUTable 4: Chemicals Injected at Oil Movement SectionUT ...............................................20 TUTable 5: Number of Storage TanksUT ..............................................................................21 TUTable 6: Number of Pipelines of PRLUT ..........................................................................22 TUTable 7: Specification of Raw WaterUT ...........................................................................23 TUTable 8: Flowrates of Water Softening UnitUT ................................................................23 TUTable 9: Specifications of water at different stagesUT .....................................................24 TUTable 10 Chemicals for Boiler Feed WaterUT .................................................................24 TUTable 11: Cooling Water SpecificationsUT ......................................................................25 TUTable 12: Cooling Water ChemicalsUT ............................................................................26 TUTable 13: Operating Conditions of BoilersUT ..................................................................27 TUTable 14: Specification of BoilersUT ...............................................................................27 TUTable 15: Operating Conditions of Waste Water Treatment PlantUT ..............................30 TUTable 16: Chemical Injection in Waste Water Treatment PlantUT ..................................31 TUTable 17: Tanks of Waste Water Treatment PlantUT .......................................................32 TUTable 18: Effluent Water Characteristics of WWTPUT ...................................................32 TUTable 19: Effluent Water Characteristics of PRLUT ........................................................33 TUTable 20: Tests of WWTPUT ...........................................................................................35 TUTable 21: Tests for Utility SectionUT ...............................................................................35 TUTable 22: Tests on Gas SamplesUT ..................................................................................36 TUTable 23: Tests on Processing Plant SamplesUT ..............................................................36 TUTable 24: Heat Exchangers of Preheating of CrudeUT .....................................................43 TUTable 25: Heat Exchangers of pre-treatment of crudeUT .................................................45 TUTable 26: Separators of Hydrotreater SectionUT ..............................................................51 TUTable 27: Schedule at DCETUT .......................................................................................62 TUTable 28: Specification of High Speed DieselUT .............................................................68 TUTable 29: Specification of Fuel OilUT ..............................................................................68 TUTable 30: Specification of LPGUT ...................................................................................69 TUTable 31: Specification of KeroseneUT ............................................................................69 TUTable 32: Specification of GasolineUT .............................................................................69 LIST OF FIGURES TUFigure 1: HSEQ Policy of PRLUT ....................................................................................12 TUFigure 2: Network of PRLUT ...........................................................................................14 TUFigure 3 Overall Process DiagramUT ...............................................................................44 TUFigure 4: Crude Distillation UnitUT .................................................................................46 TUFigure 5: Hydrotreater UnitUT .........................................................................................49 TUFigure 7: Platformer UnitUT .............................................................................................54 TUFigure 8: Platformer Stabilizer UnitUT ............................................................................56
  • 9. 9 SCHEDULE OF OVERALLACTIVITIES Date Day Activity Learning 28 July 1 HSE Orientation Safety, Environment 29 July 2 Fire Fighting 30 July 3 Oil Movement Codes & Communication 31 July 4 Pipeline Protection 1 August Off Shab-e-Mairaj Visited SeaView 2 August Saturday-1 DCET Fuel Lab. 3 August Off Recreational Tomb of Quad-e-Azam 4 August 6 Decanting & Gantry 5 August 7 Storage Tank 6 August 8 Calculations 7 August 9 Utility Cooling Tower 8 August 10 Boiler Feed Water 9 August Saturday-2 DCET Fuel Lab. 10 August Off Recreational Manora Beach 11 August 11 Boiler Sections of Boiler 12 August 12 WWTP Chemical Injection 13 August 13 Treatment Results 14 August Off Independence Day 15 August 14 Pumps& Samples Parts and Maintenance 16 August Saturday-3 DCET Fuel Lab 17 August Off Recreational Visited HawksBay 18 August Off Shab-e-Barat 19 August 15 Laboratory Daily Tests and Apparatus 20 August 16 RON Calculation, ASTM 21 August 17 Compressor Functioning and Parts 22 August 18 Generator Study of Parts 23 August Saturday-4 DCET Mass Transfer Lab. 24 August Off Recreational Shopping at Tariq Road 25 August 19 Crude / Plat Crude Unit 26 August 20 Hydrotreater Unit 27 August 21 Platformer Unit 28 August 22 Panel Control Room 29 August Friday Recreational Visited Gaddani
  • 10. 10 EXECUTIVE SUMMARY It was an excellent opportunity to be at a prestigious industry like PRL. The learning from this internship is indeed a valuable asset and is helpful for our professional life. We got an opportunity to observe ongoing industrial practices which is undoubtedly very helpful for us to understand industrial environment and different stages of operations and processes taking place in a refinery in particular. On the first day we undertook the HSE Orientation session wherein we were familiarized with the Personal Protective Equipment (PPEs) and other safety precautionary measures we need to keep in mind while moving around in the plant or in PRL as a whole. We received safety goggles, helmet, earplugs and an overall so that we can observe the process closely in the plant. After HSE orientation we were given a schedule which comprised of the following sections: • Oil Movement • Utility • Boiler • Waste Water Treatment Plant • Pumps and samples • Laboratory • Compressors • Generators • Crude Plate • Panel We managed to explore gantry, decanting and crude pump sections in Oil Movement Department. There we noticed the way of communication between Kemari and Korangi terminals to use the pipelines for pumping products and crude. We also visited the storage tanks under construction and repair. Decanting section next to gantry is there to receive local crude and condensates from different fields of Sindh. Some chemical additives are also added specially in kerosene to form JP-1 and JP-8 as aviation fuel. Crude pumps take crude from storage tanks to the processing plant with inline mixing of local crude. In Utility section we learned about Water Treatment Plant, Cooling Towers and Reverse Osmosis Plant (not functioning at the moment). We concentrated on its processes and operations with keen interest as every industry has a utility section and boiler feed water plant. Water Treatment Plant is water softening unit wherein hardness is removed by cation exchange process in two cation exchangers (Sodium Zeolite and Hydrogen-Zeolite). There are two cross flow Cooling Towers. We also visited the RO Plant and were able to see the membrane filters. There are three D type water tube Boilers with 45000 lb/hr capacity each generating super heated steam used in running turbines and as heating medium in strippers. In the
  • 11. 11 Waste Water Treatment Plant, water drained from plant is treated with microbes to overcome environmental problems it can cause. This waste water is discharged to the sea after treatment. Laboratory session was like an overview of the whole plant keeping a vigilant check and control of all the quality parameters. We saw Engine for Research Octane Number (RON) Calculation, Total Sulfur Analyzer, Bomb Calorimeter and JFTOT for thermal stability of jet fuels. PRL also owns the only Detailed Hydrocarbon Analyzer in Pakistan. Crude Processing Plant is being run by electricity connections and incase of electricity failure PRL owns two Diesel Generators which take load of the plant. We observed the color coding, understood the coding in the process plant for vessel, furnaces, towers, pumps and compressors, heat exchangers and reactors. There are some general pipelines which are normally seen at every section of plant like HP and LP steam lines, fire water, cooling water, fuel gas supply, and instrument air lines. This plant is producing the following products • LPG • Gasoline • Platformate (MS) • Naphtha (Export Naphtha + Light Naphtha) • Kerosene (JP1 and JP8) • Diesel (HSD) • Residue or Furnace Oil. Gas companies adjacent to PRL, SHELLGAS, FONGAS and SCHEVRON take LPG directly from the plant and store it in their own storage tanks. There is no LPG storage tank in PRL.
  • 12. 12 Figure 1: HSEQ Policy of PRL (Courtesy: www. prl.com.pk)
  • 13. 13 1. COMPANY PROFILE Introduction Pakistan Refinery Limited was established in 1962. It is providing fuel to the marketing companies of Shell, PSO and Chevron (previously known as Caltex) with production rate of 50,000 barrels per day. Shell is the main shareholder among the rest, details of which is given below Table 1: Shareholders of PRL SHAREHOLDERS CATEGORY PERCENTAGE OF ISSUED CAPITAL Shell 30% PSO 18% Chevron 12% Insurance & Financial Institutions 25% General Public 15% It is producing LPG, Gasoline, Kerosene, Jet Fuel, High Speed Diesel, Furnace Oil and Naphtha –the Export Product. The following are some specifications of the products sold in year 2007-2008. Table 2: Production of Year 2007-2008 Production in year 2007-2008 Metric TON Specifications LPG 10,020 40 % PROPANE 60 % BUTANE GASOLINE 120,000 UNLEADED RON 90 KEROSENE 24,000 HYDROTREATED & SMOKE 24 mm JET FUEL JP-1 175,000 MEETS DEFENCE & COMMERCIAL AIRCRAFT INTERNATIONAL SPECIFICATIONS JET FUEL JP-8 78,000 High Speed Diesel 577,512 SULPHUR 1 % BY Wt. CETANE No.50 FURNACE OIL 987,504 SULPHUR 3 % BY Wt. VISCOSITY: SUMMER-180 CST WINTER-125 CST NAPHTHA- EXPORT 170,627
  • 14. 14 Figure 2: Network of PRL
  • 15. 15 UNITS OF PRL KORANGI TERMINAL Mainly PRL comprises of: Crude Distillation Unit Hydrodesulphurization Unit Platformer Unit Boiler Unit Utilities - Water Treatment Units. Power Generators & Desalination Plant Tank farm - Storage facilities for Crude and Products Main Office Building Pipelines 12" dia. Crude Line from Keamari Terminal to Korangi 10" dia. Furnace Oil/HSD from Keamari Terminal to Korangi 8" dia. White Oil Pipeline from Keamari Terminal to Korangi 8" dia. PRL - PARCO, Korangi System 6" dia. JP-1 Cross-country Pipeline from Korangi to Jinnah Airport 6" dia Fuel Oil from Keamari Terminal to KESC Achievements PRL is proudly a leader in Health Safety & Environment (HSE) Management System and is the first in Pakistan to achieve ISO 14001 and OHSAS 18001 certification in November 2002. Some of the achievements are highlighted as under: Revamped the Platformer Unit to achieve capacity enhancement (from 340 to 450 Metric Tons per Stream Day (MTSD) and have also improved our energy efficiency quotient. Have recently benchmarked Refinery performance with other Refineries of the world and have positioned ourselves as one of the top performers in HSE and in Operating Costs within the hydro skimming sector. Installed and commissioned a state-of-the-art Waste Water Treatment Plant to meet National Environment and Quality Standards (NEQS). Have started the production and supply of unleaded 90 RON Motor Gasoline. Have completed a major modification to the crude heaters. In consequence thereof High Speed Diesel (HSD) yield increased by about 2% by weight and improved furnace efficiency by 10%. Have had the PRL laboratory ISO 9001 certified since 1999.
  • 16. 16 Have converted the Fuel Oil x-country pipeline to HSD service from August 20, 2000, thereby bridging the gap between the Keamari Port and the PARCO pipeline system. Have inducted a Desalting Unit to improve quality of Fuel Oil. Upgraded / Modified the Instrumentation by installing a Distributed Control System and initiated the induction of an Advance Process Control System. Have installed a Desalination Plant. We are currently meeting about 30% of our water needs through this facility. Introduced SAP software for Inventory and Plant Maintenance Management and for the production of company financials. Commissioned the Fuel Oil gantry project at Korangi terminal in July, 2000. Production of Liquid Petroleum Gas (LPG) increased from 40 to 65 MTSD in August, 1996. Eased infrastructure constraints by offering tanks at Keamari to marketing companies and thereby facilitated receipt of imported HSD. For further information: HTUwww.prl.com.pkUTH
  • 17. 17 2. HSEQ ORIENTATION The Policy deals with Health, Safety, Environment and Quality of every activity going on which affects the performance of PRL. i) Health: minimize effluents, emissions of gases, and proper treatment of waste ii) Safety: to ensure safety one should follow standards iii) Environment: PRL follows National Environment Quality Standards (NEQS) under Ministry of Environment of Pakistan, provide monthly reports of their environmental parameters to Sinth and Pakistan EPAs (Environmental Protection Agency) iv) Quality: Product Quality, teamwork, innovations The objective of HSEQ Department is to create awareness of safety to the employees and keep regulating the practices as defined in the Standard Operating Procedures Manual (SOPM). HSE Department concentrated on the following areas in our orientation session: a) Awareness to PRL Health, Safety, Environment and Quality Management Systems b) Importance of conformance with HSEQ Policy, Procedures, requirements of HSEQ Management System and benefits of improved personal performance c) Awareness of HSE Hazards and Risks d) Awareness of possible emergencies and emergency procedures e) Importance and use of Personal Protective Equipments f) Permit to Work System g) Material Safety Datasheets h) Firefighting i) First Aid During the orientation we were provided safety shoes, safety goggles, safety helmet earplugs and overall which we placed in the cabinets reserved for internees. Every morning we changed our dress and put on these PPEs to enter the plant area otherwise no one is allowed to enter. Workers ought to have safety gloves otherwise they will not be allowed to work at any point in the plant. Fire drill HSE Engineers along with the fire department conduct a weekly fire drill with sole purpose of keeping the fire fighting skills alive to treat any unwanted emergency of any type on the plant. Every Tuesday at 8:30 a.m. HSE department give briefing on parts of fire extinguisher, use of fire extinguisher and wind direction. Right at 9 am the fire alarm is activated and utility operator starts the designated water pump for this particular fire
  • 18. 18 fighting session. All the firemen in morning shift along with other employees and the internees as per the schedule participate in this practice. The firefighting practice is carried out at the ground adjacent to Waste Water Treatment Plant. The firefighting convoy comprises of a fire fighting truck, an ambulance and a jeep for HSE Engineers. Initially fire is ignited on a mini oil storage tank and then top fire extinguishing system is demonstrated where foam is sprinkled all over the tank surface. Now the difficulty level is raised and in the absence of top extinguishing system the fire on the oil is extinguished by the foam injected at the bottom which covers the surface and kills the fire. Another fire is lighted on the spilled oil and this time a special high flow nozzle is used which carpets the oil surface with thicker layer of foam. Simultaneously the fire extinguishers are also used. Finally the atmosphere is cooled by showering the water from the pipeline coming through the fire truck taking the feed from the fire line already networked in the plant. The fire fighting water for extinguishing contains 97 % water and 3 % Foam. In all this demonstration on the morning of Tuesday July 29, 2008 we understood all the main fire fighting systems which are helpful to overcome the serious fires at the different areas of the plant. Incase of burns the ambulance contains fire blankets, polymer jackets which are used to cover the body and put out the fire if there still remains any. It is also equipped with a stretcher, oxygen cylinder and mask along with First Aid Box. Initially the patient is taken to dispensary in PRL and then to any nearby hospital. Fire Fighting Equipment To keep supplying the water one of the 5 pumps of firewater is used to maintain the pressure at 4 to 5 kg/cmP 2 P. There are three fire trucks in fire department. Numerous fire extinguishers are placed at many plant sites which are more likely to be on fire. A fire extinguisher has a pipe which is held in hand and the top lever is pressed which blows compressed gas to the fire. The appropriate use is to blow in the direction of wind and at a safe distance from fire.
  • 19. 19 3. OIL MOVEMENT In this department we saw the gantry, decanting and crude pump sections. There we explored the communication between Keamari and Korangi terminals. We also visited the storage tanks under construction and repair which we no doubt is a rare opportunity. The products were also sent from this section to Keamari terminal and other pipelines. Some chemical additives are also added specially in kerosene to form JP-1 and JP-8 as aviation fuel. Grades of Crude Oil There are more than 360 grades of crude oil available out of which PRL utilizes Light Arabian (Saudi Arab), Irani Heavy and Irani Light (Iran), Murpan and Upper Zaikhun (Abu-Dhabi) and Qatar Marine (Qatar). Local Crude Oil is received from interior Sindh from the following sites: Table 3: Grades of Crude Oil used in PRL Crude Condensate UTP OGDC UTP OGDC • Tangri • Khaskeli • Laghari • Ghungro • Tando Alam • Sono • Lashari • Pasakhi • Pasakhi North • Bukhari • Qadirpur • Kand Kot Some of the condensates are also received from Sehwan (Bit) and Daru (Zamzama). Gantry Gantry section is the product filling section where tank vehicles are filled and sent to the destination from PRL. Because of pipeline network this was not in use. This section can handle 8 tank vehicles at a time. Mainly temperature, specific gravity, volume and other product specifications are enlisted on a paper as a record at the time of filling which are sent along the vehicle. Decanting Decanting section next to gantry unloads the local crude and condensates from different fields of Sindh in tank vehicles. This section can handle 12 tank vehicles at a
  • 20. 20 time. When the tankers reach PRL about 8 to 10 hour settling time is provided based on the nature of product in the tanker. Mainly crude, mixed crude and condensates are received. First of all the safety valves and leakage is checked. The tank vehicle is earthed to avoid any static charge which can cause a spark. The specific gravity is checked by the hydrometer. A sample of the tank is sent to the laboratory for testing. To measure the water contents a dipping rod with yellow paste is used to dip into the tank vehicle from above. Incase of water the yellow color goes red. This indicates the extent of water present in the product. In our observation out of the 12 tank vehicles none had moisture content as no red color was found. Table 4: Chemicals Injected at Oil Movement Section Additive Purpose Added to Amount Para Flow Pour point depressant HSD, Fuel oil 250 ppm Sepa Flux Pour Point depressant HSD, Fuel oil 500-1000ppm AO-80 Anti Oxidant JP-1 20 ppm Stadius-450 Anti Static charge JP-1, JP-4 3 ppm Hi-Tech 580 Anti Corrosive JP-4 25 ppm Red Dye Gasoline Orange Dye Gasoline Storage Tanks PRL owns 52 tanks in both terminals out of which 40 tanks are in Korangi (processing site) and 12 tanks are at Keamari terminal. 4 Tanks are under construction. There are generally three types of Storage tanks we have seen in PRL. We noticed that there was no LPG storage vessel which is typically spherical in shape but apart from this we found two shapes of liquid storage tanks, Conical and Flat Roofs. Tanks are alike huge cylinders. They can have a floating screen as well. There are openings in the tank on the wall near the top to maintain the pressure in and outside the tank above the screen. These are called Stationery Roof with Floating Screen. Screen is made up of Aluminum. Luckily three of us got an opportunity to see the open tank with Aluminum screen. It has many stands attached on the bottom to keep it a distance from the bottom of the tank. There is a rod which keeps the screen aligned and hence with minimized friction with the wall. It is used to avoid the vapors collection on the top of the liquid level of the Crude Oil or any product stored in the tank. The tank with movable roof is called Floating Roof. The roof is also made up of Mild Steel. It moves up and down with the level of the liquid in the tank. It has a movable ladder on the top which is used to support the roof and provide path to step onto the roof. There is a special drainage system for this type of tank on the top. The rain water collected on the top of the tank drains out without contacting with the stored liquid.
  • 21. 21 One of the floating roof tanks which we could see from inside was weighing 60 ton having 45 ft height and 160 ft diameter. Auxiliaries of Storage Tanks To save the tank from any unwanted fire there is a waterline with a sprinkler attached which is used to control the temperature by showering water on the top of the tank. There is a foam line at 5 different spots on the top of the tank which supply foam to extinguish the fire. A set of 4 bearings assembled together is used to keep the contact of the roof and screen with the ground. Tank is filled by the inlet pipeline connected on the sidewall near bottom and there is an outlet pipeline which takes out the product from the storage tank. Every storage tank has an electrically run mixer with agitator to homogenize the tank product. There is one drain line to drain out the rain water. There is a level indicator attached which helps to reveal the volume of the stored product present in the tank. The overall storage details of products and feed crude is given below in the table: Table 5: Number of Storage Tanks Product No. of Tanks Gross Capacity (Metric Ton) Working Capacity (Metric ton) Crude 16 175,879 139,001 MS (Motor Spirit) / Gasoline 2 3,900 3,700 Kerosene 2 2,400 2,200 JP-1 3 8,550 7550 JP-8 1 2,450 2200 HSD (High Speed Diesel) 5 13,000 12,500 Fuel Oil 4 28,380 26,750 Naphtha –Export 9 26,500 25,080 Reformate 1 1,200 1,150 SLOP 5 2,000 1,750 Condensate 2 1,375 1,300 Heavy Naphtha 2 3,890 3,556 Total 52 269,524 226,737 Pipeline protection The pipelines in PRL are spread both in outside and underground fashion and are protected by using Cathodic Protection - a technique to control the corrosion of a metal surface by making it work as a cathode of an electrochemical cell, achieved by placing in contact with the metal to be protected where an easily corroded metal acts as the anode of the electrochemical cell. The underground pipelines are also painted with bitumen to save them from corroding.
  • 22. 22 Table 6: Number of Pipelines of PRL Pipeline Diameter Length Crude Line from Keamari Terminal to Korangi 12" 16 km Furnace Oil/HSD from Keamari Terminal to Korangi 10" 16 km White Oil Pipeline from Keamari Terminal to Korangi 8" 16 km PRL - PARCO, Korangi System 8" 1.5 km JP-1 Cross-country Pipeline from Korangi to Jinnah Airport 6" 18 km Fuel Oil from Keamari Terminal to KESC 6" 3 km Crude Pumping Crude pumps operated with steam turbines are pumping crude from storage tanks to the processing plant. There are two centrifugal turbine run pumps for crude. Only one at a time is operative and the other is on standby. The crude is pumped at the pressure of 21 kg/cmP 2 P at a flow rate of 278 Metric ton per hour (MT/hr). The pumps are installed below the ground level to get maximum NPSH (Net Positive Suction Head) for the pump in operation. The crude is taken from 8 different storage tanks containing the foreign crude. 1 tank is of local crude and this crude is blended inline using an electric powered pump at 85 MT/hr flow rate and at a pressure of 5 kg/cmP 2 P which together with foreign crude reaches the plant area after going through mixing and blending within the pipeline. The steam run turbines produce Low Pressure Steam which is fed to a condenser installed at the crude pump section. This condenser condenses the Low Pressure Steam to condensate water which is pumped to the Condensate Tank in the Utilities Section.
  • 23. 23 4. UTILITIES This is comprised of Water Treatment Plant, Cooling Towers and Reverse Osmosis Plant. We concentrated on its processes and operations with keen interest as every industry has a utility section and boiler feed water plants. All the water in this utility section is taken from KDA which is stored in two reservoirs. There is fire water pipelines spread in whole site of PRL which is primarily for the fire fighting purpose. A Pressure of 5 kg/cmP 2 P is maintained in the whole network of pipelines. Table 7: Specification of Raw Water Parameter Range pH 8.0 – 8.5 Total dissolved solids 250 – 350 Total hardness 90 – 150 Calcium hardness 70 – 110 Sodium chloride 50 – 100 M Value 90 – 150 Water Treatment Plant for Boilers Water treatment plant is mainly water softening unit wherein hardness is removed by cation exchange process in two cation exchangers. First cation exchanger has Sodium- Zeolite and in other Hydrogen-Zeolite is used. The regeneration of these catalysts is being done by concentrated brine and sulfuric acid respectively. Water from reservoir contains impurities mainly Calcium and Magnesium salts which cause hardness and unwanted dissolved Oxygen. This water if used in boilers for steam generation it can cause scaling on inner surfaces of boiler tubes which reduces heat transfer thus fuel consumption is increased. When this water is softened through softening units of Sodium Zeolite and Hydrogen Zeolite, the water then received has lower pH and is acidic in nature. Dissolved Oxygen and acids present can result into serious corrosion problems in boilers and steam lines. To treat dissolved oxygen neutralizing ammines (scavenger) are added in water to avoid corrosion. The water treatment process has three main units, sand filter Cation exchangers, Base exchanger, de-gasifier, and de-aerator then enters boiler. Table 8: Flowrates of Water Softening Unit Water Softener Flow (MTD) US-Gallon Cation Exchanger 69 8032 Base Exchanger 97 39495
  • 24. 24 Treatment Process Water passes through a pressurized sand filter at 50 psi having spherical silica as filter media. This much pressure is to keep the bed undisturbed otherwise can result in poor efficiency. It filters for particles up to 10 microns. There are two output lines; one goes to cation exchanger while the other goes to base exchanger. Water can enter from top and bottom of these units depending upon the operation of the unit. It consists of Sodium ions in the presence of a synthetic zeolite resin where Magnesium and Calcium ions are replaced with Sodium ions. These are called Base exchangers and pH here is maintained from 7 to 8. In the next unit Sodium ions are exchanged with hydrogen producing acids lowering the pH of the water from 2 to 3. Exchangers are being operated at a flow rate of 150 gallons per minute and are being operated in down-flow fashion. Both lines meet together and a pH of 4.5 is maintained which is then fed to de-gasifier to remove Carbon Dioxide gas by providing air from a blower from the bottom of the unit where pH changes from 4.5 to 7.8. Table 9: Specifications of water at different stages Water Total Hardness pH Conductivity Combine water < 2 4.2 After COB 2B removal < 2 7.8 After caustic addition < 2 8.0 – 8.5 Condensate < 1 8.5 – 9.5 < 10 Boiler Feed water < 2 9.0 – 9.5 150 - 225 Now this treated water is pumped to the treated water tank from where it is pumped to the de-aerator in which a pressure of 1.2 kg/cmP 2 P is maintained by using low pressure steam. The Oxygen level in De-aerator at inlet is about 2 - 3 ppm and at the outlet it decreases to 5 ppb. Table 10 Chemicals for Boiler Feed Water Chemical Composition Purpose NALCO 72210 • Polymer • Potassium Hydroxide • Phosphate Hardness Removal TRI-ACT • 2-Diethylaminoethanol • Cyclo hexamine Corrosion inhibitor NALCO 750 • Polyglycol solution Anti-foaming Regeneration of Cation and Base exchangers There are branches at both exchangers attached with ejector to add brine solution from brine tank into the base exchanger and dilute sulphuric acid into the cation exchanger for regeneration. The flow in each of the unit is recorded on a flow meter.
  • 25. 25 The effluents from both the exchangers combine together and enter into the de- gasifier. From de-gasifier the combine effluent goes to treated water tank. Dilute caustic solution is injected in treated water to raise its pH value if required with the help of a reciprocating pump. Treated water is then pumped to de-aerator through a split level control valve which controls level in the de-aerator and then it goes to the boiler for steam generation. The feed water after degasification enters the de-aerator along with Sulphides and phosphates from which it is ready to be sent in the boiler section. Cooling Tower The water is supplied to the cooling water basin by raw water pumps working for both cooling tower and water treatment plant. The cooling water lines are in a closed loop and only the make up water is drawn to cover the losses. There are two cross flow Cooling Towers which provide cooling water at 30 P o PC for cooling purposes in different condensers and trim coolers, whereas the received water in the cooling tower is at 40 P o PC. Table 11: Cooling Water Specifications Parameter Range Wet Bulb Temperature 25 P o PC Supply Temperature 30 P o PC Return temperature 41 P o PC Return Flow 41696 MTD Evaporation 819 MTD Blow Down 220 MTD Drift Losses 83 MTD Theoretical Make up 1123 MTD Actual makeup 1094 MTD Efficiency 69 % pH 8 – 9 NaCl < 500 ppm M-Alkalanity < 700 ppm Zn 1 – 2 ppm Free Halogens < 1 ppm Total dissolved Solids < 1500 Total hardness < 800 Calcium Hardness < 500 Chemicals are added to cooling water basin through PD Pumps to avoid steel and copper alloys corrosions, precipitation of alkaline earth salts, deposition of corrosion products and microbiological fouling. Some of the data is provided here:
  • 26. 26 Table 12: Cooling Water Chemicals Chemical Composition Purpose SCGON 345 Poly carboxylic Phospheno Carboxylic acid Zinc Salts pH maintenance provide multi metal protection against corrosion Chlorine HOCl To prevent microbial action SYNCHEM 789 Aqueous solution of tributyl- tetradecyl phosphonium Controls microbiological fouling Now this cooling water is filtered by sieves on suction line of cooling water pumps. Water passes through a pressurized sand filter at 50 psi having spherical silica as filter and refluxed back to the cooling water basin to keep it free from suspensions. The pressure is to keep the bed undisturbed otherwise can result in poor efficiency. It filters for particles up to 10 microns. Reverse Osmosis Plant We also visited the RO Plant and were able to see the membrane filters and a special centrifugal pump with 5 propellers for high pressure. Currently it is not in operation because of malfunctioning of membranes. When in operation it takes bore water from the PRL ground and passes through the operations of filtration at three levels, chemical addition and finally to the reverse osmosis membranes where suspended solids up to nanometer are removed. First the bore water is pumped into the Feed vessel from where water is pumped to 3 filters. First two sand filters may be operated in parallel or in series while the third one is in series with the outlet of sand filters. This third filter is filled with activated carbon and filter up to 20 micron particle size. After filtration chemical dosing of FLOCON 260 (solution of HCl) is done via pd pumps. Water now enters the 4 cartridge filters which are connected in parallel and filter up to 5 microns. Here two pumps are available to pump the water into the reverse osmosis membranes, one in operation and other on standby. Reverse Osmosis Membranes are of Polyamide construction and are spiral thin film composite membranes. Water at desired reverse osmotic pressure (250 psi) is fed to 2 stages RO Unit which comprises 4 membranes. In first stage three membranes are arranged in parallel from where reject is separated and enters to the second stage (single membrane). The permeate from first and second stage is led to a storage tank from where it may be transferred to the cooling tower basin or de-gasifier for boiler feed water. This High Pressure Steam after motor drive action in turbine is received as condensate after condensation in condensers in the condensate storage tank which is again used in the boiler.
  • 27. 27 5. BOILERS Steam is generated in three D type boilers each having a capacity of 45000 lbs per hour of superheated steam at a pressure of 20 kg/cmP 2 P. Boilers include: burners, a combustion air system, the boiler enclosure (in which the heat transfer takes place), a draft or pressure system to remove flue gas from the furnace, soot blowers and compressed air systems that seal openings to prevent the escape of flue gas from furnace box. Super heater provides 290 P o PC temperature for superheating. Boiler consists of a number of tubes that carry the water steam mixture through the furnaces for maximum heat transfer. These tubes run between steam distribution drums at the top of the boilers and water collector drum at the bottom of the boiler. Steam flows from the steam drum to the super-heater before entering the steam distribution system. Table 13: Operating Conditions of Boilers Pressure Temperature Flow Rate Inlet Air 31 kg/cmP 2 P 8190mP 3 P/hr Boiler Feed Water 1.71 kg/cmP 2 P 130 P o PC 85 MT/hr Fuel Gas 0.324 kg/cmP 2 P 159mP 3 P/hr Furnace Oil 1.17 kg/cmP 2 P 71 P o PC 103 kg/hr Super Heated Steam 20 kg/cmP 2 P 275P o PC 8.19 MT/hr Flue Gases -14.8 mmHB 2BO (draft) 270 P o PC Table 14: Specification of Boilers Parameter Range Condensate Return 292 MTD Boiler 1 efficiency 80 % Boiler 2 efficiency 82 % Boiler 3 efficiency 83 % Boiler Feed Water 663 MTD pH 11 – 12 Specific conductivity 4000 – 5400 microS / cm POB 4PB -2 P 20 – 50 ppm Total Hardness < 1 ppm Steam 615 MTD Atmospheric Steam 6 MTD Blow Down 6.3 % OB 2B in BFW 1.9 ppb Oil Flow 6.8 MTD
  • 28. 28 Cyclones and the special dry pipes are fitted in the steam drum to provide saturated dry steam to super heater that is saturated steam free of any entrant water. The operation of the boiler is governed by so called thermo-siphon principle. The tubes exposed to the radiant section are heated more than the tubes shielded off from the firebox. More steam is formed in those tubes consequently the density of steam water mixer is less than the tubes shielded off from the firebox. The difference in the density causes the circulation of thermo-siphoning. The former tubes are called riser tubes and the later the down comer tubes. There are 658 tubes in one boiler. The boiler is utilizing natural gas and furnace oil as fuel and steam as atomizer of furnace oil.
  • 29. 29 6. WASTE WATER TREATMENT PLANT Waste water treatment is normally done for processed material, runoff and sewerage water at any plant. PRL is treating the laboratory and drain water of process plant before discharging into the sea nearby. Waste water typically contains hydrocarbons, dissolved material, suspended solids, phenols, ammonia, sulphides and other compounds. Waste water includes condensed steam, stripping water, spent caustic solution, cooling tower and boiler blow down, wash water, alkaline, and acid waste neutralization water. Therefore these wastes are treated in three treatment processes. Pre-treatment Operation: Here the separation of hydrocarbons and solids from waste water, API Separator, interceptor plates and settling ponds remove suspended hydrocarbons; oily sludge and solids by gravity separation, skimming and filtration. Some oil in water emulsions must be heated to assist in separating the oil and water. Gravity Separation depends on the specific gravity differences between water and immiscible oil globules and allows free oil to be skimmed off the surface of the waste water. Secondary treatment Operations: Suspended solids are removed by sedimentations or air floatation after pre-treatment. Waste water with low levels of solids may be screened or filtered. Flocculation agents are sometime added to help separations. Secondary treatment process biologically degrade and oxidize, soluble organic matter, by the use of activated sludge, un aerated or aerated lagoons, trickling filter methods or anaerobic treatment. Tertiary Treatment Operation: This treatment removes specific pollutants to meet regulatory discharge requirements. These treatments include chlorination, ozonation, ion exchange, reverse osmosis, activated carbon, etc. Compressed oxygen is diffused into waste water streams to oxidize certain chemicals or to satisfy regulatory oxygen contents requirement. Waste water that is to be recycled may require cooling to remove heat and/or oxidation by spraying or air stripping to remove any remaining phenols, nitrates or ammonia. Process Descriptions All refining waste water streams are presently treated through the existing API Separator equipped with CPI packing. The oily process water is pumped from the API to the buffer tank. This buffer tank is equipped with a pH measuring unit and a submersible mixer to obtain a homogeneous quality and to level out peaks in pH, Hydrocarbons, Sulphides and other constituents. In buffer tank 30% solution of HCl is added under water ejector system to strip out the Sulphide in the form of Hydrogen Sulphide gas. The homogenized raw water is transferred from buffer tank to physio- chemical treatment at a flow rate of 20 mP 3 P/hr, in to the Pipe-flocculator. This is followed by the Dissolved Air Flocculator (DAF) separator which serves to de- stabilize and remove the oily emulsions and colloidal suspensions that are still present in the Gravity De-oiled Waste Water from preceding API.
  • 30. 30 Table 15: Operating Conditions of Waste Water Treatment Plant Parameter Range Feed rate 20 mP 3 P / hr Holding Basin pH 9-11 Buffer Tank pH 7.7 Coiled Pipe Flocculator (CPF) pH 6.64 DAF Pressure (De-Aerator Flocculator) 6.9 bars Comp Press 5.5 kg/cmP 2 P Air flow 10 Lit/min Sludge Basin Level 53.1 % OB 2B in Oxidation basin 1.9 ppm Buffer Tank: The physio-chemical pre treatment has a specific function to remove some metals, emulsified oil droplets, free oil, suspended solids and toxic traces. The coagulation is completed by means of a pH adjustment to a value between 7 – 7.3. The precipitation is assisted by addition of a Trivalent Metal Coagulant, Aluminum Sulphates upstream of the “pH control hydrochloric injection.” Coiled Pipe Flocculator: The precipitation process takes place in a plug flow type Coiled Pipe Flocculator in which all stages of the precipitation process takes place in a sequence. The pH is continuously monitored by a pH Control loop. For de- stabilization of impurities neutralizing agent Caustic Soda, ALUM and Polyelectrolyte are injected in the pipe flocculator and pH is kept within 7 – 7.3. Tilted Pipe Flocculator: In Tilted Pipe Flocculator the de-stabilized and Flocculated Oil emulsions and Colloidal suspensions are removed by means of dissolved air flocculation process. The sludge containing the air bubbles and collected contaminants will float rapidly to the liquid surface from where it is permanently removed by means of a pneumatically driven skimmer device into the sludge compartment of the DAF Unit. From there sludge is transferred in the sludge collection basins. To dissolve the air highly compressed air is circulated by circulation compressor due to high level of turbulence and shearing forces in the pump chamber the water is saturated with air. Due to sudden pressure loss the dissolved air is released in the form of small sized air bubbles that attach themselves to the flocculated and suspended impurities. The clarified effluent is discharged under gravity to next stage that is Anoxic biological pre-selector reactor. Aerobic Biological Treatment The physically / chemically treated water flows under gravity from the DAF Unit directly into the first pre-selector compartment of the biological continuous activated sludge treatment installation. In this flow if needed FeClB 3B is injected in a
  • 31. 31 concentration of 5 ppm in order to eliminate the present sulphide. The FeP 3+ P will react as intermediary agent for the oxidization of SP 2- P and SOB 4PB 2- P.P The biological system starts with a two stage anoxic pre-selector in which in the first box pre-selector the re-cycle sludge is pumped back from the secondary clarifier intimately mixed with the raw water under temporarily oxygen pore conditions. The pre-operating conditions promote according to common experience. The growth of microbial species that are capable of rapidly adsorbing and absorbing substrate in a strictly substrate limiting and anoxic environment enable a quick removal of soluble COD / BOD in the reactors. Biological Oxidation The actual digestion of the organic waste is accomplished in the biological oxidation basin where ample time is available for the microbes to oxidatively digest the waste that was previously adsorbed in the pre-selector. The microbes drive their energy from the oxidative digestion part of which they apply for a pre-synthesis of their cell tissues. The re-synthesis ultimately results in the cell fusion and in an increase of the total activated sludge population. The major part of digestive energy will not be used by the activated sludge instead it is released to the environment in the form of heat. The effect is most noticeable during cold periods. The temperature of the basin contents is then well above ambient. Clarification The segregation of the activated sludge from the treated effluent is accomplished in two parallel operating settling basins. These are of the Inhofe type (operating without rotating equipment). The segregation takes place slowly under the influence of gravity. The slide density difference between the flocculated activated sludge and the surrounding water is sufficient to have the sludge flocks settled to the lower region of the settler. Particles that don’t rapidly flocculate for any reason are trapped to a large extent in the activated sludge flocks and filtered out. The clarified water has the high clarity as a result provided the quantities are known flocculated particles don’t exceed the captured capacity of the activated sludge. The clarified water is directly discharged into the clarified water basin and from there to the sea in the presence of V notches. This helps to maintain a constant flow rate of 20mP 3 P/hr. Table 16: Chemical Injection in Waste Water Treatment Plant Chemical Conc. (ppm) V. Flowrate (Lit / hr) NaOH 60 1.2 HCl 72 1.4 Poly Electrolyte 0.5 0.01 ALUM 326 6.5
  • 32. 32 Table 17: Tanks of Waste Water Treatment Plant Parameters (ppm) Holding Basin Buffer Tank Outlet TPF Outlet Oxidation Basin Clarifier Pit pH 8 – 8.5 7 – 7.3 7 – 8.5 7 – 8.5 Sulphide 5 – 15 < 3 < 1 0.1 – 1 Alkalines 250 – 350 150 – 250 100 – 150 100 – 150 TSS 40 – 120 5 – 10 30 – 200 MLSS 3500 MLVSS 2500 SV 450 SVB 1B 80 – 120 Oil and Grease 30 - 50 20 – 40 2 – 10 Table 18: Effluent Water Characteristics of WWTP Parameter (ppm) Tank Drain Process Drain Spent Caustic Cooling Tower Blow Down WWC Drain Boiler Blow Down Distilled Crude Water Separator RO Rejected pH 7.3 8.8 13.3 9.9 6.2 11.6 6.7 6.9 TDS 3685 3087 179900 1708 299 3315 195 12600 TSS 22 28 337 59.5 55 12.6 11.6 7 Total Hardness 680 560 532 520 160 1 10 630 CaP 2+ P 280 272 280 120 0.8 8 360 MgP 2+ P 400 288 240 100 0.2 2 270 Alkalinity 530 352 650 100 280 60 320 COB 3PB 2- P 112 352 330 184 HCOB 3PB 1- P 418 320 100 96 60 320 OHP 1- P ClP 1- P 2457 2105 420 70 1813 28.5 5600 BOD COD 147 64 133000 136 765 Oil and Grease 19.7 10.5 16 18 30.3
  • 33. 33 Table 19: Effluent Water Characteristics of PRL Components (ppm) PRL Effluent Normal Values NEQS WWTP Design Values pH 8.5 – 9.5 6 – 9 7 – 8.5 TDS 2000 – 3000 3500 Temperature 30 40 30 – 35 Oil and grease 10 – 20 10 < 0.1 Sulphide 13 1 < 0.1 COD 450 150 < 50 BOD 120 80 < 5 Phenol 1 – 7 0.1 < 0.5 Ammonia 1 40 TSS 50 200 30
  • 34. 34 7. PUMPS AND SAMPLES In this session we focused on the different types of pumps under operation in the plant and different mechanical sections. Fundamentally a pump has a prime mover either turbine or an electric motor. Lube oil and cooling water (for lube oil cooling) are also used in some pumps dealing hot fluids. The Positive Displacement Pumps are efficient in generating pressure and Centrifugal pumps are efficient in providing a high flow rate. General Parts of pump are: • Outer bearing, • Inner bearing lubricated for less friction, • Pump bearing, • Impeller (some also have propellers right before discharge) • Coupling (to connect shaft) • Governor (controls the rpm of the pump) • Strainer (filters the feed) • No Return Valve (NRV) used at discharge line • Pressure gauge at discharge line Note: There is no impeller in Positive Displacement pump. At the suction side there is a strainer which filters the feed and at the discharge end there is a No-Return-Valve which prevents the back flow of the fluid. Generally the feed pipe is greater in diameter than the discharge line. All these points are regularly inspected. The rpm is checked by a meter called Tachometer where two scales are visible. The digit under continuous vibration indicates the rpm of the pump onto which it is placed. Samples of numerous pumps are regularly taken out after every 4 hours to keep an eye on the properties of the process line onto which these pumps are connected. Actions are taken if test results show deviations.
  • 35. 35 8. LABORATORY Laboratory gives an overview of the parameters of the whole plant keeping a vigilant check of all the quality parameters and reports the deviations. In short this is an indispensable and vital part of processing plant. Some are regular tests like doctor test, pour point and flash point, pH , viscosity and conductivity determinations, calculation of Research Octane Number (RON), distillation for initial and end boiling points some sophisticated tests are also conducted details of which is given below periodically. There are regular or routine tests conducted in the lab and some are done on need basis. Regularly tests are generally done for Waster Water Plant, Utility Water and Plant samples including fuels. Waste Water Treatment Plant Samples are received from 5 different points and following tests are conducted at every point to check for the prevailing conditions to analyze the performance. Table 20: Tests of WWTP Water Sample Tests Holding Basin pH, Conductivity, Sulphide (SP 2- P) Buffer Tank pH, Conductivity, Sulphide Tilted Pipe Flocculator pH, Sulphide Oxidation basin pH, Total Alkalinity, Sludge Volume, Mixed Liquor Suspended Solids Clarified Pit pH, Sulphide Discharge Water to Sea pH, Sodium Chloride in ppm Table 21: Tests for Utility Section Sample Tests Blow Down (Boiler 1, 2, 3) Total Hardness, Phosphate and Sulphite, pH, Conductivity, Total Dissolved Solids Condensate pH, total Hardness Degasifier pH, Total Hardness De-aerator Treated Water pH, Total Hardness Boiler Feed Water pH, Total Hardness Raw Water pH, Total Hardness, Conductivity, Total Dissolved Solids, NaCl in ppm, CaP 2+ P Hardness, M-Value Cooling Water pH, Total Hardness, conductivity, Total Dissolved Solids, NaCl in ppm, CaP 2+ PHardness, M-Value, ZnP 2+ P Test, Halogen test Reverse Osmosis Samples pH, Total Hardness
  • 36. 36 Table 22: Tests on Gas Samples Tests Recycle Gas Plate Stabilizer Overhead Combine Flue Gases Relative Density (RD) HCl (ppm) HB 2BS (ppm) Table 23: Tests on Processing Plant Samples Tests Gas Oil Kerosene Naphtha Gasoline Platformate Specific Gravity 60/60 Distillation Initial Boiling Point • 10 % • 50% • 90% • End Point Doctor Test Flash Point Color ASTM Cloud Point Pour Point Reid Vapor Pressure @100 F, (psi) Research Octane Number Sulphur % mass Apart from normal laboratory apparatus like pH meter, Ovens Furnaces, Chillers Conductometers, viscometer and hydrometer, Laboratory in PRL is equipped with a lot of sophisticated and standard testing equipment some of which are mentioned below: 1. Engine for RON Calculation: Octane number is measured by comparison method as per ASTM described in D2699, D2700 and D2885. This engine has 4 sample cylinders in all in which 2 cylinders are for sample fuels and 2 for standard fuels (known mixture of iso-Octane and n-Heptane). It has a piston engine cylinder and its height is controlled using readings from the knock- meter. The engine is having a coolant unit and air inlet. Compression ratio is controlled by level of cylinder height which varies and produces increase and decrease in knocking piston sound. This has two meters showing height in mm
  • 37. 37 with 6 mm difference between them. From barometric pressure and length of cylinder Theoretical Octane Number (TON) is noted from the standard chart. 2. JFTOT for JP fuels: Using this equipment thermal stability of Jet Fuel is calculated. This is qualitative test revealing the resistance of the fuel to the thermal oxidation or degradation at high pressure and high temperature. The fuel is heated. The aviation fuel passes through high pressure and temperature through a specific filter which gives a pressure drop. When composition remains unchanged the pressure difference remains stable but when composition changes the pressure drop decreases which reveals that the fuel is thermally decomposing. This test is conducted to check the quality of the aviation fuel which is to meet the market requirement of thermal stability. 3. Atmospheric distillation unit: This equipment is in fact a laboratory scale distillation unit wherein a sample of crude is distilled out at nearly atmospheric pressure. The electric heater heats the feed crude up to 375 P o PC and products are received at the cuts in the distillation column. LPG 0 – 40 Light Naphtha 40 – 110 Heavy Naphtha 110 – 145 Kerosene 145 – 235 Gas oil 235 – 370 Residue 370 + This helps to analyze the crude sample and estimate the product quantity when run in the plant 4. Vacuum Distillation Unit: Crude residue composition is checked by vacuum distillation equipment and the analysis of products is carried out. 5. Automatic Absorption Spectroscope: This equipment is used to detect the quantity of certain metals in ppm present in the specimen. There are different lights for different metal detections. 6. Bomb Calorimeter: This measures the calorific value of the fuels. An electronic device is attached through which precise calorific value is calculated after combustion of the sample in this unit. 7. Total Sulphur Analyzer: This computer attached electronic device is for complete analysis of Sulphur in the specimen. This is indeed a sophisticated equipment but very precise in Sulphur Analysis. 8. Automatic / manual Flash Point: The sample is added to the cylinder of the analyzer wherein input of an estimated range of flash point is given to the electronic controller. The heater heats the sample at a controlled rate specified. The equipment checks for flash by using a spark periodically within that range and precisely measures the flash point. On achieving flash point the heater is turned off and alarm is activated. Incase the range specified is in-correct; again alarm turns on and attracts attention.
  • 38. 38 9. Manual / Automatic Cloud and Pour Point: This equipment has a chilled cold water tank at the bottom with cylinders for sample on the top dipped in the chilled water when added to the container. This test is specifically done for viscous fuels like Gas oil to measure its extent of fluidity and crystallization measured by Pour Point and Cloud Point respectively. 10. Detailed Hydrocarbon Analyzer: The laboratory also owns THE ONLY Detailed Hydrocarbon Analyzer (DHA) in Pakistan which determines the detailed ultimate analysis of a hydrocarbon sample in terms of each and every component present in the specimen. 11. De-pentanisation Apparatus: This analysis the extent of Paraffin, Olefins, Naphthanes and Aromatics (PONA) present in a sample especially for Platformate and Gasoline. It is also called PONA Test. 12. Shape meter(for moisture contents of LPG gas) 13. Infrared Spectroscope(FTIR Spectrometer) 14. Gas Chromatography Apparatus 15. Moisture Analyzer by Corn-Fischer Technique 16. Biological Oxygen Demand (BOD) Test 17. Automatic viscometer 18. Oxygen Stability for motor Spirit 19. Incubators 20. Aniline Point Testing Equipment 21. Sulphur Determination by LAMP Method 22. MSEP Meter Micro Separator for JPs and Emulsification plus Surfactants 23. Centrifuge Machine 24. CFPP for high Speed Diesel (in place of Cloud Point) The library of laboratory is frequently consulted for precision and accuracy of the tests as per the ASTM and UOP instruction manuals. Laboratory manual is updated and contains the concise information of all the tests taking place in the lab along with references of the test methods of the standard Manuals like ASTM.
  • 39. 39 9. COMPRESSORS There are 8 compressors in which 6 are reciprocating and 2 are centrifugal compressors. Compressors are attached to Platformer Unit, Hydrotreater Unit and LPG units and for instrument air. There are two compressors attached to every unit; one is in running condition and other is for standby operations. Reciprocating Compressor for Hydrogen Sulphide Gas This compressor takes suction from overhead separator vessel containing overhead gases of fractionator column, condensed water and oil fractions. The operating pressure is about 0.2 to 0.3 kg/cmP 2 P and discharge pressure to stabilizer tower separating LPG and gasoline where operating pressure is 0.6 kg/cmP 2 P. This is double stage reciprocating compressor for Hydrogen Sulphide. In first stage pressure is raised between 2.5 to 3 kg/cmP 2 P and in the second stage it is raised up to 6.5 kg/cmP 2 P. Reciprocating Compressor for Hydrogen Gas This is a single stage, double cylinder and double acting reciprocating compressor. The platformer gas is the main source of hydrogen supply to the hydrotreater. At present all the platformer gas along with some gas from the hydrotreater system [HP Separator] is circulated through the hydrotreater to ensure the sufficiently high hydrogen partial pressure. This compressor takes suction from platformer separator 301 F, HP separator and MP separator. This hydrocarbon gas is rich in Hydrogen. There is a knock out vessel where any entrant liquid is knocked out. The gas free of any liquid goes to the single stage, double cylinder and double acting reciprocating compressor. The suction pressure of the gas is usually 20 kg/cmP 2 P and discharge pressure is about 40 kg/cmP 2 P. Multi-Stage Centrifugal Compressor for Hydrogen Gas This recycle gas compressor is a five stage centrifugal compressor that takes suction from platformer separator 301F and recycles the gas in the same unit. The hydrogen rich gas is used to form a protective layer on the catalyst surface resulting in a long cycle length of catalyst. The suction pressure is about 24 kg/cmP 2 P while the discharge pressure is about 27 kg/cmP 2 P. Air Compressors These are reciprocating compressors for instrument air and for platformer / hydro catalyst regenerator and service air compressor. Both the compressors take suction from atmosphere and boost the pressure up to the required level. There is a knock out vessel from which compressed vapors are released from the bottom in the form of water.
  • 40. 40 Generally a compressor has two axillaries namely Oil Sump and Lube Oil. Lube oil is for the lubrication of the rods and shaft for frictionless motion whereas oil sump is for the compression vessel which is surrounded by oil to avoid any leakage. Mainly reciprocating compressor has more compression ratio as compared to centrifugal compressor. Reciprocating Compressor is efficient to inject the discharge in a pressurized line whereas centrifugal compressor is used for high flow rate.
  • 41. 41 10. GENERATORS The whole plant has two electric supplies namely BS1 and BS2. Incase of power failure at one connection the load shifts to the other. Sometimes the power from both sections fails in that emergency PRL owns two diesel generators of 1500KVA and 1300KVA. The diesel generator consists of two parts, diesel engine and AC generator exciter. It is totally enclosed turbo charged cooled pressure lubricated mechanical injection four stoke diesel engine. There are twelve cylinders arranged in “Y” formation. Each cylinder has 10” diameter bore and 12“stroke. There are two banks rear and front and there are 6 cylinders in each bank. The sequence of four stroke cycle is: 1P st P Stroke: Induction takes place 2P nd P Stroke: Compression occurs 3P rd P Stroke: Power stroke, rapid firing and rise in pressure in the cylinder 4P th P Stroke: Exhaust of flue gases Continuations of these cycles provide high pressure flue gases which move the turbine of turbo blowers. This moves the shaft and hence electricity is generated in the second portion of the generator that is AC generator and exciter. It generates 3 phase electricity for the plant. In case of emergency generator is connected with the following units to keep the plant in running condition: • All Air Coolers • Injection Pumps • Control Room Air conditioning • Instrument Power Supply • Flare Ignition Supply • Lights in Control room (4) • Lights in process Area (13) • Radio Wireless Set • Cooling Tower Fans • Instrument Air Compressor • Raw Water Pump • Treated Water Pump • Fuel Pumps • Boiler Feed Water Pumps • Cooling Water Circulation Pumps
  • 42. 42 11. FURNACES The heaters are usually designed for specific process operations and most are of cylindrical vertical or box types design. We have seen both types of furnaces. Furnaces here are for mainly Crude Unit, Hydrotreater Furnaces and Platformer Furnaces. All furnaces have one stack of height 175 feet. Furnaces for Crude: There are three furnaces for crude, two of which are box type with 28 burners each and one is cylindrical vertical having 15 burners. Furnace for Hydrotreater: One furnace is for Hydrotreater having 6 burners at the bottom based on fuel gas (Natural Gas) and furnace oil. Furnaces for Platformer: There are three furnaces for platformer having 6 burners each and of cylindrical vertical type. All the Furnaces are fired on refinery or natural gas and fuel oil. The combination of all three types of fuels can also be used. All the burners have the pilot burners. Steam is used in the burners to atomize and provide high temperature to furnace oil for combustion.
  • 43. 43 12. CRUDE / PLAT Now the crude oil from the Crude Pump in Oil Movement Section reaches the plant area at a flow rate of 278 MT/hr and a Pressure of 21 kg/cmP 2 P. It is pre-heated in three shell and tube heat exchangers. Pre-heating 1P st P heat exchanger: Crude is in the tube side and is heated by the top reflux of distillation unit in the shell side hence the temperature is increased. 2P nd P Heat Exchanger: This heated crude now enters the tube side of 2P nd P heater exchanger heated by Kerosene Product line from the fractionation column in the shell side up to 90P o PC. 3P rd P Heat Exchanger: It is further heated in the tube side using Gas Oil Product line from distillation column in the shell side. The temperature of crude oil reaches up to 105 P o PC. Table 24: Heat Exchangers of Preheating of Crude Unit Heat Exchanger 1 Heat Exchanger 2 Heat Exchanger 3 Inlet temperature 34 P o PC 70 P o PC 90 P o PC Outlet Temperature 70 P o PC 90 P o PC 105 P o PC Inlet Pressure 21 kg/cmP 2 P 17 kg/cmP 2 P 16.5 kg/cmP 2 P Outlet Pressure 17 kg/cmP 2 P 16.5 kg/cmP 2 P 15.75 kg/cmP 2 P Pre-treatment Heated Crude is treated in desalter unit to remove salts like MgCl, CaCl, SOB 4PB 2- P and COB 3PB 2- P. It enters at a pressure of 15.55 kg/cmP 2 P through a control valve which allows only 15.35 kg/cmP 2 P pressure before entering the Desalter Vessel. Desalter: It contains two oppositely charged electrodes for electrolysis in the presence of water operated at 440 V and 12 – 14 KW. The wash water level is maintained at 20 percent of the vessel. Because of electrolysis process the salts are attracted to the electrodes and hence in the water making crude free from salts. The oil water interface is controlled by a level controller and is withdrawn from the vessel by a level control valve. The effluent water from desalter transfers its heat to incoming water to make emulsion in a shell and tube heat exchanger. Then it is further cooled in a trim cooler and ultimately it is sent to API separator. In the vessel upper level contains pure crude at the bottom lies the pure water, in the middle an emulsion of oil and water. From the top crude is drawn out at 15 kg/cmP 2 P. Heating before distillation tower: Desalted crude oil is heated up to 210 P o PC in three shell and tube heat exchangers.
  • 44. 44 OVERALL PROCESS DIAGRAM Figure 3 Overall Process Diagram
  • 45. 45 1P st PHeat Exchanger: Crude enters at 100 P o PC and at a pressure of 14.95 kg/cmP 2 P in to the tube side and heated up to 130 P o PC and by exchanging heat with residue of distillation column (Furnace Oil). 2P nd P Heat Exchanger: Again it is heated in tube side by inter-reflux of distillation column in the shell side (contains gas oil). 3P rd PHeat Exchanger: Now residue line from the atmospheric distillation column in the shell side is used to heat crude up to 210 P o PC. Table 25: Heat Exchangers of pre-treatment of crude Unit Heat Exchanger 1 Heat Exchanger 2 Heat Exchanger 3 Inlet temperature 100 P o PC 130 P o PC 170 P o PC Outlet Temperature 130 P o PC 170 P o PC 210 P o PC Inlet Pressure 14.95 kg/cmP 2 P 14.85 kg/cmP 2 P 12.80 kg/cmP 2 P Outlet Pressure 14.85 kg/cmP 2 P 13.00 kg/cmP 2 P 12.25 kg/cmP 2 P Furnace: Pre-heated crude enters three furnaces at the temperature of 210 P o PC and a pressure of 12.5 kg/cmP 2 P. The crude is heated up to 360 P o PC by the flue gases of furnace oil and fuel gas burnt in the shell side of the furnace working under natural draft principle. Crude enters in the atmospheric distillation unit at a temperature of 350 P o PC, pressure of 1.45 kg/cmP 2 P and flow rate of 6259 MTD. Note: The temperature of 350 P o PC is an optimum temperature above which there is a risk of crude oil cracking in crude furnace tube. Cracking if occur cokes up crude furnace tube. 1- Atmospheric Distillation Column The crude distillation tower consists of 20 plates in which upper 8 are bubble cap and lower 12 are sieve plates. The feed is received on 16P th P plate in the column. There are 9 cuts on the column apart from the residue, out of which the top is received as overhead, at 1P st P plate top reflux of condensate is received, at 4P th P plate lies liquid outlet which is later received as top reflux, inter reflux cut, over head of stripper column is received, at 10P th P plate gas oil is received which is then taken to striper column, then at the bottom a super heated steam line is present and finally the residue is taken out from the bottom line. At the top: 1.5 kg/cmP 2 P and 195 P o PC At the bottom: 1.6 kg/cmP 2 Pand 337 P o PC Stripping Steam: Super heated steam is injected at the bottom of crude distillation column at a flow rate of 101 MTD, pressure 1.7 kg/cmP 2 Pand temperature 365 P o PC. The steam strips out more volatile hydrocarbons from the residue. Residue: it is received at the bottom of the distillation column at the temperature of 337 P o PC. Then temperature of residue is lowered by passing it through three shell and tube heat exchangers.
  • 46. 46 CRUDE DISTILLATION UNIT Figure 4: Crude Distillation Unit
  • 47. 47 1P st P Heat Exchanger: The residue is passed through the tube side of heat exchange where it transfers its heat to the kerosene passing through shell side of the exchanger. 2P nd P Heat Exchanger: Again residue is passed through another heat exchanger on the shell side and the temperature is lowered by transferring the heat to crude feed on the tube side of the exchanger. 3P rd P Heat Exchanger: This residue is further cooled by passing it from 3P rd P heat exchanger on shell side and cooled by the crude flowing on the tube side. Air Cooler: The residue is cooled by air coolers for further removal of heat. Trim Cooler: Finally it is passed by a trim cooler where cooling water cools the residue and is drawn out at a temperature of 64 P o PC. It is finally sent to residue storage tank. Gas Oil Gas oil is drawn off from the 10P th P plate in distillation column and sent to stripper for the removal of volatile components. Stripper: Stripping steam is injected at the bottom of the stripper at a flow rate of 11 MTD and temperature 365 P o PC which strips out the volatile components. According to the lab results 90 % distillation should not be at 365 P o PC. Higher temperature than 365 P o PC will increase pour point. Sulpher contents should not be more than 1 % in the gas oil. The overhead containing volatile hydrocarbons from stripper are sent back to the distillation column. The bottom product is gas oil and is taken out at temperature 274 P o PC. Now it is pumped to the heat exchangers for cooling. 1P st P Heat Exchanger: The gas oil is passed through the tube side of shell and tube heat exchanger exchanging heat with splitter feed flowing on the shell side. 2P nd P Heat Exchanger: Again gas oil is pumped to another shell and tube heat exchanger on shell side, giving heat to the crude flowing on the tube side. Air Cooler: For further cooling, gas oil is passed through the air coolers which lower the temperature of gas oil using air. Trim Cooler: Finally gas oil is cooled in a trim cooler by cooling water flowing on the tube side of the shell and tube heat exchanger. Reflux: In crude distillation column, reflux is injected to maintain the temperature in the distillation column. In crude distillation column two refluxes are injected: Top Reflux: Liquid from the 3P rd P plate is taken out from the distillation column at a temperature of 198 P o PC by a pump and after exchanging the heat it is injected in the column on 1P st P plate. Top reflux flowing in shell side of heat exchanger transfers heat to the crude flowing on tube side of heat exchanger.
  • 48. 48 Inter Reflux: Liquid from the 10P th P plate is taken out at 215 P o PC and passed through the heat exchangers. In first heat exchanger, inter reflux flowing on tube side is cooled by naphtha on shell side of the heat exchanger. In 2P nd P exchanger, inter reflux on tube side provides its heat to the gasoline on the shell side. Inter reflux is pumped back to distillation column at a temperature of 50 P o PC. Overhead: Overhead is received from the top of the distillation column at a temperature of 195 P o PC and a pressure of 1.5 kg/cmP 2 Pcontaining vapors of volatile hydrocarbons. Condenser: Overhead is passed through a shell and tube condenser in which the overhead condenses. Overhead is passed through the tube side of the condenser and condenses transferring heat to splitter feed flowing on shell side of condenser. Air Cooler: Condensed overhead is passed through the air coolers in which the temperature is lowered. Trim Cooler: Again the condensed overhead is passed through a heat exchanger on shell side and exchanges its heat with cooling water flowing on the tube side of exchanger. 3-Phase Separator Vessel: After passing through the trim cooler, overhead is taken to the 3-stage separator vessel at a temperature of 50 P o PC. In this vessel, gases, liquefied hydrocarbons and water are separated. Water is drained out from the bottom of the vessel and the gases (usually LPG and Gasoline) are sent to the stabilizer tower. A pressure of 0.7 – 0.9 kg/cmP 2 P is maintained in the separator vessel which helps in the separation. Filter Coalescer: The liquefied hydrocarbon is passed through a filter and then pumped to the Hydrotreater unit at a temperature of 55 P o PC and a pressure of 37 kg/cmP 2 P.P 2- Hydrotreater Hydrotreating for sulphur removal is called hydro-desulphurization. In a typical catalytic hydrodesulphurization unit, the feed stock is mixed with hydrogen, preheated in a fired heater and charged under pressure through a fixed bed catalytic reactor. In the reactor the sulphur and nitrogen compounds in the feedstock are converted into HB 2BS and NHB 3B. The reaction products leave the reactor and after cooling to a low temperature enter a liquid gas separator. The hydrogen rich gas from the high pressure separation is recycled to combine with the feedstock and the low pressure gas stream rich in HB 2BS is sent to a gas treating unit where HB 2BS is removed. The clean gas is then used as fuel gas or refinery gas in the furnace whereas the liquid stream is taken out as product. Hence objective of removal of Sulphur and Nitrogen components is achieved.
  • 49. 49 HYDROTREATER UNIT Figure 5: Hydrotreater Unit
  • 50. 50 Process The condensed overhead hydrocarbons from 3-phase separating vessel are pumped to heat exchangers for pre-heating. In this stream compressed hydrogen gas from platformer unit is injected at a temperature of 60 P o PC and pressure 36 kg/cmP 2 P using a reciprocating compressor which joins the liquid feed before it enters the series of heat exchangers. The hydro feed enters at the shell side of the heat exchangers and its temperature is raised up to 270 P o PC by using reactor effluent flowing on the tube side having temperature 300 P o PC. Furnace: The pre-heated feed enters into the furnace (cylindrical vertical) with 4 coils which altogether heats the charge up to 300 P o PC and the flue gases temperature from the furnace is 440 P o PC on average. This heated charge now enters the reactor. Reactor: The reactor vessel is being operated at 300 P o PC and 33 kg/cmP 2 P in the presence of Cobalt Oxide and Molybdenum Oxide with ALUMINA as carrier on supporting balls present on upper and lower part of the catalyst. The Sulphur and Nitrogen compounds are chemically converted to HB 2BS and NHB 3 Brespectively by reacting with HB 2B in the presence of above mentioned catalysts. The products are then sent to air cooler after passing through the same pre-heating series of heat exchangers of hydrotreater feed line. Air Cooler: The reactor effluent is further cooled in air cooler up to 65 P o PC at 31.5 kg/cmP 2 P. The gases are separated in three high, medium and low pressure separating vessels after passing through the air cooler. High Pressure Separator: After cooling it enters the High Pressure (HP) Separator where the bulk of the Hydrogen is separated from the liquid. The hydrogen is recycled in the system and can also be flared or be put into the fuel gas mainline as per the operational demands. Medium Pressure Separator: The liquid from the HP Separator is pressured through Level Control Valve into the Medium Pressure (MP) Separator. This vessel is similar in construction to the HP Separator. In this vessel more Hydrogen rich gas is released from the liquid which go to the suction of a single stage reciprocating compressor having two cylinders which provides Hydrogen gas for Platforming unit in the next stage. The pressure in this vessel is controlled by pressure regulating controller which releases the gas to the fuel gas system. Low Pressure Separator: Liquid from the MP Separator is pressured through level controller in to Low Pressure (LP) separator. The gas is further released from this vessel which is of low purity. The Liquid is now sent to the Splitter Tower (fractionator).
  • 51. 51 Table 26: Separators of Hydrotreater Section Parameter HP Separator MP Separator LP Separator Inlet Pressure 31.5 kg/cmP 2 P 31 kg/cmP 2 P 14.5 kg/cmP 2 P Outlet Pressure 31 kg/cmP 2 P 14.5 kg/cmP 2 P 5 kg/cmP 2 P Liq. + Vap. Flow rate 2318 MTD 2312 MTD 2300 MTD (Liq.) 3 – Splitter In splitter tower the splitter feed from Hydrotreater is further split in to further products. This column consists of 22 plates. The splitter feed from the Hydrotreater is received on 17P th P plate. There are 7 cuts in splitter tower. From top overhead containing LPG and gasoline is sent to stabilizer unit, Kerosene is received on the bottom is sent to the storage tank as product, naphtha is obtained from 10P th P plate and is sent to naphtha stripper, two for re-boiler and rest of the cuts are for refluxes of LPG and naphtha. Splitter feed is obtained from Hydrotreater product streamline which is preheated in three Shell and Tube heat exchangers where its temperature is raised from 65 P o PC to 170 P o PC at a flow rate of 2300 MTD. 1P st P heat exchanger (Condenser for overhead of distillation column): Splitter feed enters in the shell side and is heated by overhead of crude distillation column. 2P nd P Heat Exchanger: It is further heated in shell side with gas oil in tubes. 3P rd P Heat Exchanger: Now finally the splitter feed is further heated in shell side by inter-reflux of crude tower containing gas oil. Re-boiler: The residue from the bottom is taken to the re-boiler where it is re-boiled in shell side using crude tower residue at tube side. There is a steam ring attached to this heat exchanger on the outer surface of tube sheet which maintains the temperature. Residue/Kerosene: This is taken out from the bottom of splitter tower at a flow rate of 1300 MTD at 200 P o PC and 0.8 kg/cmP 2 P. Kerosene is cooled through a series of heat exchangers before going out the process plant to the storage tank. Heat exchanger: Kerosene transfers its heat from shell side for pre-heating of crude in the tube side which is later sent for desalting. Trim coolers: Some heat is lost to the water in the tube side of the cooler where kerosene is at the shell side of the heat exchanger. Kerosene is discharged to the storage tank at flow rate of 1300 MTD and a temperature of 48P o PC. Overhead: Overhead is received from the top of the splitter tower at a flow rate of 550 MTD, 92 P o PC and at a pressure of 0.74 kg/cmP 2 P. It is passed through a trim cooler in which cooling water is flowing on the tube side.
  • 52. 52 3-Phase Separating Vessel: After cooling overhead is received in three stage vessel where water, hydrocarbon and gases are separated. Gases are sent to the stabilizer by using double stage reciprocating compressor for Hydrogen Sulphide. In first stage pressure is raised between 2.5 to 3 kg/cmP 2 P and in the second stage it is raised up to 6.5 kg/cmP 2 P. Water is drained to waste water treatment plant and the hydrocarbon part is pumped to the stabilizer tower. One branch of hydrocarbon is refluxed to the splitter tower at 45 P o PC. Naphtha Stripper: Naphtha from 10P th P plate at 130 P o PC is sent to the Naphtha stripper where volatile components like LPG and Gasoline are removed and sent back to splitter tower. Naphtha stripper contains 8 plates. From the bottom of the naphtha stripper, naphtha is taken out at temperature of 149 P o PC and pumped to platformer unit at a pressure of 450 kg/cmP 2 P. A branch of naphtha is sent to naphtha stripper as reflux after passing through a heat exchanger. In heat exchanger the naphtha is heated up to 240 P o PC flowing on shell side by the inter reflux of crude tower on tube side. 4 – Stabilizer Stabilizer is also a distillation column in which LPG and Gasoline are separated. Stabilizer column consists of 24 plates. Feed is charged in to the stabilizer at a flow rate of 370 MTD, pressure 6 kg/cmP 2 P and temperature 45 P o PC. Gases from the 3-phase separating vessels are also charged in to stabilizer as feed. From the top of the column, LPG is collected and further sent to Caustic Treatment Column (CTC). From the bottom Gasoline is taken out and sent to the storage tanks. Re-boiler: From the 24P th P plate, residue (Gasoline) is taken out at 127 P o PC and charged to the re-boiler where it re-boils on the shell side by the inter reflux of crude distillation column and temperature is raised up to 137 P o PC. Gasoline: Gasoline is received from the bottom of the stabilizer at temperature 135 P o PC which is further cooled before pumping to storage tank. Air Cooler: Gasoline is first cooled in the air coolers by the air and then sent to the heat exchanger. Trim Cooler: Gasoline is charged in to trim cooler on the shell side and cooled by the cooling water flowing on the tube side of the exchanger. LPG: LPG gas is taken out from the top of the stabilizer at 56 P o PC. After compressing by reciprocating compressor, it is passed through a trim cooler on the shell side and exchanges its heat with cooling water on the tube side of exchanger. Knock-out Vessel: It is sent to a knock-out vessel where gases are separated from the LPG and discharged to the flare line at flow rate of 25 MTD at a pressure of 5.8 kg/cmP 2 Pand temperature 38 P o PC. From the bottom of the vessel the LPG is sent to the Caustic Treatment Column (CTC) at a flow rate of 65 MTD, 7.5 kg/cmP 2 Ppressure and at a temperature of 38P o PC. One branch of LPG is refluxed to the stabilizer on the 1P st P plate at 40 P o PC.
  • 53. 53 Water Column: LPG is taken to the water column in which water is showered from the top of the column and gas is injected from the bottom of the column. In this water column, impurities are separated from the LPG. It is then sent to the CTC for further treatment. Caustic Treatment Column: After the removal of impurities, LPG is charged to the CTC, in which 30 – 35 % solution of Caustic Soda is showered from the top of the column. In this column HB 2BS gas which is present in the LPG is removed chemically and from the bottom NaB 2BS is received which is drained out. From the top LPG is taken out and further charged to the water column. Water Column: LPG is charged in to second water column where caustic soda traces are removed from the LPG and drained from the bottom of the column. Pure LPG is then taken out and supplied to the gas companies namely (SHELL GAS, FONGAS and SCHEVRON). 5 – Platformer Catalytic reforming is an important process used to convert low-octane naphtha into high-octane gasoline blending components called Reformate. Reforming represents the total effect of numerous reactions such as cracking, polymerization, dehydrogenation and isomerization taking place simultaneously. Depending on the properties of the naphtha feed stock as measured by PONA test (Paraffin, Olefins, Naphthene and Aromatic contents) and catalyst used. Reformate can be produced with very high concentration of toluene, benzene, xylene and other aromatics used in gasoline blending and petrochemical processing. Hydrogen, a significant by-product, is separated from the reformate for reuse in the processes. In platforming process, the first step is preparation of naphtha feed to remove impurities from the naphtha and reduce catalyst degradation. Catalysts used in this process are Platinum mixed with Rhenium. The naphtha stock is then mixed with hydrogen gas, vaporized and passed through a series of alternating furnaces and fixed bed reactors containing catalyst as mentioned above. The effluent from the last reactor is cooled and sent to a separator to permit removal of hydrogen rich gas stream from the top of the separator for recycling. The liquid product from the bottom of the separator is sent to Plat-Stabilizer. It makes a bottom product called reformate; butanes and lighter go overhead.
  • 54. 54 Figure 6: Platformer Unit
  • 55. 55 Process Naphtha from splitter tower is pumped to a series of heat exchanger for preheating before entering the furnaces and reactors. Before preheating hydrogen gas having temperature 32P o PC and pressure 24 kg/cmP 2 P is mixed with naphtha by using a single stage, double cylinder and double acting reciprocating compressor. Heat Exchanger: Naphtha is preheated in a series of heat exchangers flowing on the tube side of the exchangers and gets heat from the reactor effluent of platforming process flowing on the shell side of the exchangers. The temperature of the feed is raised up to 440 P o PC. 1P st P Furnace: Preheated naphtha is charged to the furnace for further heating. In the cylindrical vertical type furnace, feed is heated up to 487 P o PC having pressure 26.7 kg/cmP 2 P. Then heated feed is sent to reactor. 1P st P Reactor: In the reactor octane number of naphtha is increased and numerous simultaneous reactions are taking place in the presence of catalyst bed. 2P nd P Furnace: The output of 1P st P reactor is charged to the 2P nd P furnace for heating. In the furnace feed is heated up to 487 P o PC and having pressure 26 kg/cmP 2 P. After heating, the feed is charged to the 2P nd P reactor. 2P nd P Reactor: In 2P nd P reactor, more cyclo compounds are converted in to aromatic compounds in the presence of catalyst. 3P rd P Furnace: Output of the 2P nd P reactor is again further heated in the 3P rd P furnace where the temperature of the feed is raised up to 487 P o PC having pressure 25.5 kg/cmP 2 P. 3P rd P Reactor: This line feed is charged to the 3P rd P reactor where maximum RON and maximum number of cyclo compounds are converted into the aromatic compounds. Effluent from the reactor is called Reformate and is at 478 P o PC and pressure 25 kg/cmP 2 P. The reformate is passed through a vertical heat exchanger where the temperature of reformate is decreased to 95 P o PC by exchanging the heat with naphtha feed to Platformate. Air Cooler: After passing through heat exchanger reformate is cooled in the air cooler. Trim Cooler: Again reformate is cooled in a trim cooler flowing on shell side by using cooling water flowing on the tube side of the exchanger. Knock-out Vessel: This reformate is sent to a knock-out vessel where the excess hydrogen gas is separated and sent back to the feed of hydrotreater by reciprocating compressor. In the vessel liquid flow rate is 391 MTD, gas flow rate is 254 MTD, temperature is 32 P o PC and pressure is 24 kg/cmP 2 P.
  • 56. 56 PLATFORMER STABILIZER UNIT Figure 7: Platformer Stabilizer Unit Heat Exchanger: Reformate from the vessel is charged to heat exchanger for the high temperature before entering in the Plat-Stabilizer. Plat-Stabilizer: In plat-stabilizer, more gases are removed. Gases are collected from the top of the column. This liquid is further cooled in tubes of the trim cooler then it is sent to reflux drum. Reflux Drum: In reflux drum gases (fuel gas) are separated from the liquid. These gases are sent to hydrotreater at 37 P o PC and 15.2 kg/cmP 2 P. Gases going out from the reflux drum are sweet gases (free from sulpher). From the bottom of the reflux drum liquid is sent to buffer tank. One branch is sent to plat-stabilizer as reflux. From the bottom of the column product is received called Platformate having RON about 90. Re-boiler Furnace: From the bottom of the column a line is taken out to the re-boiler furnace where the residue is re-boiled and charged to the plat-stabilizer. Heat Exchanger: Hot platformate is taken to the heat exchangers where the temperature of the platformate is dropped up to 58 P o PC. The liquid flows at 374 MTD with and at a pressure of 15 kg/cmP 2 P. After cooling, platformate is sent to the storage tanks.
  • 57. 57 13. MISCELLANEOUS Work Permits For any work PRL has designed work permits for proper attention to the nature of work going to take place on a particular section or equipment in the plant keeping in view the safety considerations. These are renewed on daily basis and can be re- evaluated thrice. Except New Project work permit rest all expire after 28 days. Following are the work permits used in PRL: 1. Cold Work Permit 2. Hot work permit 3. Crane Operation Work Permit 4. Height Work Permit 5. New Project/Major Tank Repair Work Permit 6. Hot/Cold/Outside Refinery/Thermal Premises Certificates 1. Radiography Certificate 2. Isolation Certificate 3. Confine Space Certificate 4. Excavation Certificate Every permit or certificate has 3 copies White Control Room Pink Fire Section Hard Self / Worker Coding We observed the color coding according to which: red pipes are for fire water blue pipes are for cold water silver pipes for aviation fuel yellow pipes of fuel gas / sui gas gray pipes for overhead vapors white pipes for instrument air We also understood the coding in the process plant according to which 100 figure is used for crude processing units 200 for Hydrotreater Units 300 for platforming units 600 for LPG
  • 58. 58 The vessel, furnaces, and towers are also given codes E for Tower J for Pumps and Compressors C for Heat Exchangers and Condensers B for Furnace F for Vessel D for Reactors Main High Pressure Steam line: This line goes to all pump turbines. Low Pressure Steam Line: From the exhaust of turbine pumps low pressure steam goes to a common header. Part of this steam goes to the de-aerator, the other part is superheated in the four coils in the convection section of the crude furnace. This superheated steam goes to distillation column and fractionator column as stripping steam. The surplus super heated steam is vented to atmosphere. Fire and Service Steam Line: From the main header a line goes to a pressure controller valve where the down stream pressure of steam is regulated to 8 to 9 kg/cmP 2 P. This is fire steam which then goes to a common manifold. From the manifold two steam lines reach the furnace. 1 is for atomizing the fuel in the burners and the other is for purging the furnace combustion chamber. When this steam is used for atomizing fuel oil then the differential pressure between atomizing steam and fuel oil pressure is maintained by a Pressure Differential Indicator Controller (PDIC) which keeps atomizing steam pressure about 4 kg/cmP 2 P (higher than the fuel oil pressure). By- passes are also provided on each PDIC. From the fire steam header off take points are located at convenient areas with steam lenses. These are the service steam points. Cooling Water Main: There are two main lines for cooling water; cooling water supply and warm water return. Each of the water coolers and steam condensers are connected to both the mains. Fuel Supply Main: There are two fuel oil lines, supply lines and return lines. The supply lines have a valve manifold from where the fuel oil goes to the individual furnaces. Similarly from the individual furnaces the return lines go to a common manifold. On the fuel oil supply line to each furnace there is a pressure indicator controller which maintains the constant fuel pressure for each burner. The supply line electrically heated, which rise the temperature of fuel oil to about 95 P o PC. Fuel Gas Main: The fuel gas from different sources goes to a knock out vessel then it goes to pressure control valve where the pressure of the gas going to the furnace is regulated. From pressure control valve the fuel gas goes to a common manifold room where it goes to individual furnaces. On each furnace is a pressure indicator controller PIC. The desired crude furnace outlet temperature is set on a temperature recorder controller TRC. The TRC can be made to act on the fuel oil or fuel gas control valve by an air switch located in the control room.
  • 59. 59 Instrument Air: Dry air free from oil is supplied from a compressor to all control valves. All pumps are provided with relief valves in their discharge lines which open up if the pressure in the line is beyond the set pressure of the relieve valve. All these release valves are connected by a common header to flare lines. Release Valves located on the top of each tower release excessive pressure to atmosphere.
  • 60. 60 SUGGESTIONS PRL is efficiently utilizing all the units involved in processing of Crude for the production of products. Apart from what is present in our view PRL can also account for the processing of heavier fractions (residue from the crude distillation unit) sold as furnace oil. This residue can be further processed for production of lubricating oils paraffin waxes and asphalt. A vacuum distillation unit can serve this purpose. Another option is to imply visbreaking unit to increase production of lighter fractions from the heavier fractions like diesel and kerosene from the residue of crude distillation unit. Any extension and installation of unit in the processing plant will definitely increase the power consumption. To overcome the risks of power failures and fulfill the power requirements of extensions PRL can consider a power generation unit. When installed PRL will not be depending on electric supplies any more. There is room for more automation in the plant for valves operations. This will further shorten the time required for performing an action like opening or closing a valve other than sending a worker to do so. Apart from these considerations it is very hard to find any loopholes in the processing plant. Whatever is present is being utilized at its level best.
  • 61. 61 LEARNING EXPERIENCE AT D.C.E.T. KARACHI Apart from 5 days a week activity at PRL we used to visit DAWOOD Engineering College and Technology Karachi on 6P th P day that is Saturday, to consult library and see different experiments going on in the Fuel Lab. We were specially advised by our Internship Supervisor Engr. Aqeel Ahmed Bazmi to observe departmental activities of Department of Chemical Engineering in Dawood Engineering College. For our visits our supervisor managed to engage a faculty member Engr. Abdul Waheed Bhutto to guide us and conduct visits of the department. College Profile: Dawood College of Engineering and Technology, Karachi is a Federal Degree Awarding Institution from 31-10-2007. This college was founded by (Late) Field Marshal Muhammad Ayub Khan (Former President of Pakistan) in 1962. The institution was established by Dawood Foundation as Dawood College of Engineering and Technology. The Dawood College houses purpose built two campuses of five acre land each. The Dawood College houses purpose built two campuses of five acre land each. The main campus of the college is housed in a multi-storey building located near Quaid-e-Azam’s Mausoleum. The college offers degree programs in the field of: • Electronic Engineering, • Chemical Engineering, • Industrial Engineering & Management, • Metallurgy & Materials Engineering • Architecture. The college intends to add new disciplines relating to the cutting edge technologies in the near future. The library has been completely renovated with new furniture, fixtures, books, latest encyclopedia and ASTM Hand Books. The state of the art equipment has also been added in the laboratories of all the Engineering and Architecture programs. Learning Sessions: In four of our visits on Saturdays, Engr. Abdul Waheed Bhutto helped us in ASTM tests conducted on fuels. Finding our interests he allowed us to participate in the practicals being conducted for MSc students of Karachi University and Dr. Damani supervising the students of Karachi University entertained us alike them. We performed practicals at Fuel and Petroleum Lab which include practicals of: • Fire point, • Pour point, • Cloud point, • Smoke point • Copper Corrosion Test
  • 62. 62 as per ASTM (American Standard for Testing Material). We also spent time in mass transfer laboratory on liquid-liquid separation unit and gas absorption column. We were able to see the Computer Aided Distillation Unit. We also saw CAD-CAM based CNC machine in engineering workshop along with lathe machines for metal work. Through out this session Engr. Abdul Waheed Bhutto remained closed to us to give us a better understanding of the experiment. We are very grateful to his help and support for sharing Chemical Engineering Literature in the library. Table 27: Schedule at DCET Day 1 Pour Point and Cloud Point experiment of Diesel Day 2 Flash Point and Fire Point experiment of Kerosene Day 3 Library Consultancy and Copper Corrosion Test Day 4 Visited Engineering Workshop and Mass Transfer Lab Day 1: Pour Point: When liquid petroleum products are cooled, a point is reached at which some of the constituents begin to solidify and on continuous cooling the oil eventually seizes to flow. This temperature is the pour point limit of the oil. That means this oil will not flow until this much temperature is provided. Hence it is a test of its fluidity. A sample of diesel was taken in a cylindrical glass jar with a flat bottom and heated for sometime. It was cooled in the apparatus at a specified rate until there was no apparent movement of the surface of the oil when the jar was tilted for 5 seconds. This is setting point and the temperature is pour point temperature. Cloud Point: After achieving the pour point it is further cooled in a specified test jar. The temperature of cooling bath is maintained below the cloud point of the oil. At intervals the test jar is removed from the bath without disturbance to the oil. The temperature at which a distinct cloudiness or haziness appears in the bottom of the jar is recorded as cloud point. Day 2: Flash Point: This test is carried out to analyze both the volatility and the inflammability of the product. The flash point is the lowest temperature at which a combustible material will give off enough vapors to form an inflammable mixture with air. In general the relative volumes of liquid and vapor spaces as well as the accessibility of air to vapor space will affect the flash point. Generally there are two types of tests for flash point: Closed Cup and Open Cup. In Closed cup a measured quantity of the product is placed in a cup fitted with a lid carrying a thermometer. The oil is heated at a uniform rate and a small test flame is directed into the cup at regular intervals. The closed flash point is recorded as the lowest temperature at which a distinct flash occurs inside the cup when applied a flame.
  • 63. 63 Open Cup is used to determine the flash point of heavier products like lubricating oils and bitumen. The flame is applied with complete removal of lid. We only performed experiment on kerosene. Fire Point: After recording the flash point heating is still continued until oil burns continuously when test flame is applied. The temperature at which the continuous burning starts is called Fire Point. Day 3: Copper Corrosion Test: An ASTM test for petroleum products involve the degradation of copper strip as well. In this experiment we placed a shinny well grinded copper strip in the gasoline at a temperature of 50 P o PC. The strip was left in the gasoline for 4 hours in an apparatus. When it was taken out, the change in color was matched with the standard copper degradation color scheme and the corrosion was estimated. We could see one degree change in the color as per the color scheme. Library: Library consultation indeed helped us to explore more books of chemical engineering and different literature which is helpful to have a broader vision of chemical engineering especially “ASTM Manuals” and “Kirk Othmer Encyclopedia of Chemical Technology”. We never felt ourselves as outsiders and this encouraged us to spend more and more time. We felt very excited to look for our queries in Kirk Othmer Encyclopedia. Since we were away from our institute we could have faced problems in consulting library but conversely we were warmly welcomed by DCET for library consultation and we never felt that we are not part of this college. We are very much thankful to this down to earth support of DCET as a whole that it never let us feel we are away from our institute. We looked for theories relating all concerned topics of refinery processing for example McCabe-Thiele Method, Research Octane Number, Motor Octane Number, etc. Day 4: Engineering Workshop: We visited engineering workshop of DCET which was certainly equipped with machinery. We could see the jobs done on various equipment which include lathe machines, cutting machines, drill machines, molding machines and welding plants. Apart from these conventional machines we also saw CAD-CAM based CNC machine. This computer aided cutting machine works according to the input given to the computer on AutoCAD. The movement and cutting was done by the machine and the desired shape is obtained at the end of the job. We were shown the works of students who made different shapes using these machines. Students really worked hard on their jobs and we could clearly see the difficulty in getting that metal work. Mass Transfer Lab.: We performed a liquid liquid extraction experiment in the mass transfer lab. Herein a mixture of water and toluene under goes extraction using third
  • 64. 64 liquid benzene. Benzene helps to separate toluene from water by forming an azeotrope with toluene. Hence in this way water and toluene is separated. In the separation process, there are two positive displacement pumps for injecting the feed into the absorption column wherein there are several sieves. When the feedlines are injected from bottom and top, the two liquids undergo mass transfer operation in the column. In the column small bubbles are formed. Mass transfer takes place on the surface of the bubble. In this way benzene extracts the toluene from water mixture and pure water is received at the end. Slower the process better will be the mass transfer.
  • 65. 65 PHOTOGALLERY: ACTIVITIES IN PRL Modusser in overall and safety helmet Sitting with other internees at Tea break Catalysts used in process plant Some more Playing Table Tennis in Sports Room Basit and Khaqan waiting for Tea In the process area use of mobile phone is a safety hazard but beyond the process area we managed to get some pictures which cover our activities in PRL like in Canteen and Sports room. Catalysts displayed in the gallery are present in the training centre and are captured in a photograph with permission of HSE department.
  • 66. 66 ACTIVITES IN DAWOOD COLLEGE In the fuel lab Flash Point Apparatus Sand Filter Distillation Unit Liquid-Liquid Extraction Apparatus Condenser
  • 67. 67 Close view of distillation column and sensors Double pipe heat exchanger In DCET we performed experiments along with the other students of MSc Applied Chemistry of Karachi University and this gave us a clear picture about role of chemists in a refinery. The distillation unit in fuel lab is computer aided and is being used for research purpose. Experiments on Liquid-Liquid extraction apparatus is another source of understanding mass transfer operations.
  • 68. 68 APPENDIX Table 28: Specification of High Speed Diesel Test Description Specifications Sp. Gravity @ 60 / 60 0.82 – 0.87 Color Max 3 Flash Point P o P F 150 Cloud Point P o P F Summer : 45 – 48 Winter: 35 – 43 Cetane Index Min. 45 Sulphur % wt. Max 1 Copper Corrosion (3 hrs @ 100 P o PC) Max 1 Water % volume Max 0.05 Ash Content % wt. Max 0.01 Neutralization value • Total Acid Number mg KOH/ gm • Strong Acid Number mg KOH/gm Max 0.5 Nil Viscosity @ 40 P o PC 1.5 – 6.5 Distillation: Volume recovered @ 365 P o PC Min 90 Table 29: Specification of Fuel Oil Test Description Specifications Kinematic Viscosity 125 – 180 Flash Point P o P F Min 150 Pour Point P o P F Max 75 Sulphur Content % wt. Max 3.5 Calorific value BTU / lb 1800 Water % vol. Max 1 Sodium + Potassium (ppm) 50 Vanadium (ppm) 100
  • 69. 69 Table 30: Specification of LPG Test Description Specifications Vapor Pressure (psi) 160 95 % vol. evaporated P o P F 40 Total Sulphur 15 grains / 100 ft 3 Moisture None Copper corrosion Max. 1 Pentane and heavier % vol. 2 Table 31: Specification of Kerosene Test Description Specifications Color + 20 Saybolt Sp. Gravity @ 60 / 60 0.82 Smoke Point Min. 22 Burning Test 20 Distillation 20 % vol. recovery P o PC End point P o PC Max. 200 300 Flash pointable P o P F 95 Sulphur % wt 0.2 Mercaptan Sulphur 10 ppm Table 32: Specification of Gasoline Test Description Specifications Color Pinkish Odor Marketable RON 87 Distillation 10% vol. P o PC End Point P o PC 80 205 Sulphur % wt. 0.1 Copper strip corrosion at 50 P o PC 1 Existant gum mg / 100 ml 4 Mercaptan sulphur 10 ppm Doctor Test Negative Vapor Pressure @ 37.8 P o PC Summer: Winter: 9 psi 10 psi