1. Contents
1) ESSAR OIL LIMITED 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5)CERTIFICATE 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.0)Acknowledgement 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3) Contents 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4) ESSAR GROUP 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5) Essar Oil Ltd. 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6) Crude Distillation Unit-2 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7) Crude distillation unit (2) 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8) PFD GENERAL 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8.0)flow diagram 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9) Process Description 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9.5) Specifications of major equipments 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10) Details of major equipments (2) 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11.0)Heater Operations 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
12) Vacuum Package 57. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13) Process Control 62. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14) Flow meters 72. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15) Treaters 75. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16) Fuel oil blending 85. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
17) PROJECT heat exchanger 88. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
18) table 91. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19) Aim 92. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. Far and away the best prize that life has
to offer is the chance to work hard and
at work worth doing.
- Theodore Roosevelt

4. This is to certify that Mr. KANDARP MANSUKH MAVANI has
successfully completed his industrial training in Crude Distillation
Unit –2 and project on “Designing of heat exchanger for Crude pre
heating” during the period of 6 WEEKS (19th
May 2014 to 30th
June
2014) at the Essar Oil limited, Vadinar, Jamnagar as the partial
fulfilment of his Degree Bachelor of Technology in Chemical
Engineering at PANDIT DEENDAYAL PETROLEUM
UNIVERSITY, GANDHINAGAR.
Mr. Rajesh Gajera
Deputy General Manager Date: _/_/_
(CDU-2),
Essar Oil Ltd.

5. Acknowledgement
Wisdom knows what to do next....
Skill knows how to do it....
And Virtue is doing it....!!!
I am highly obliged to have undergone industrial training at Essar Oil Limited, Vadinar. The
industrial exposure and the quality of training were excellent.
Firstly, I am indebted to Mr. Rajesh Gajera (DGM CDU-2 unit) who despite his very busy
schedule gave me an opportunity to learn & understand the aspects of design of heat
exchanger and clear my queries and doubts whenever I approached him, he gave me very
satisfactory answer.
Secondly, I express my heartfelt gratitude to Mr. Sanyasirao Buddhana (Area Manager,
CDU-2) for giving me very valuable guidance and necessary cooperation & advices.
I would like to thank the Hr department and Transport department at ESSAR Oil Limited,
Vadinar for facilitating a smoother training process and being so co-operative.
I would also like to thank all the panel and field officers of CDU-2 and all other units for
helping me in solving my queries and also, helped me in correlating the theoretical and
practical aspects. I would also like to thank Mr. Harshal Gajbe (Student from VNIT, Nagpur)
and Mr. Sunil Sonagara (Student from PDPU, Gandhinagar) for their valuable help and their
cooperation whenever needed
I would like to thank Mr. Ramesh Dhabi and all those involved directly or indirectly who
helped me in the completion of my project.
All those above mentioned have significantly contributed in making this work an interesting
and rare industrial learning experience.
I also wish to extend my gratefulness to the whole ESSAR Oil Limited for allowing me to be
a Summer Intern at Essar Oil Limited, Vadinar.
Thanking You,
Regards,
Kandarp Mavani

6. Abstract
This report prepared at ESSAR Oil Limited, Vadinar contains a brief description of the Essar
Oil Limited with Refinery process overview and flow diagram. This report contains a detailed
description of Crude Distillation Unit-2 and project on Heat Exchanger Design as a focus
area.
The details of the project done as a part of practical training along with the details of the
methodology and procedure adapted as a part of project work is also presented in this report.

7. Preface
The objective of educational institution is to empower with knowledge both theoretically as
well as practically. A clear understanding of the classroom teaching was brought to the force
during the industrial training at ESSAR Oil Limited.
Theory of any subject is important but without its practical knowledge it becomes useless
particularly for engineering students.
An engineering student cannot become perfect engineer without undergoing practical
understanding and application of theories to industries. Hence, an in plant training provides
the golden opportunity for an engineering student to interact in the industrial working
environment.
This report on plant training has made carefully, which contains introduction about the
ESSAR Group, ESSAR Oil Refinery at Vadinar. The Subject focus area is the Crude Distillation
Unit –2 and heat exchanger design.
Working in a crucial sector like the Oil & Gas comes with a lots of safety precautions that
needs to be adhered strictly. This was also an important part of my training where
inculcation of safety practices through Safety Induction trainings was pre-requisite to
observe industrial discipline during the entire training duration.

8. Contents
1. Preface
2. Essar Group Profile
3. Essar Oil Limited
4. Refinery Overview
5. Crude Distillation Distillation Unit-2
i. Introduction of Unit
ii. General Considerations
iii. Process Description
iv. Specifications of Major equipments
v. Details of Major Equipments
6. Heater Operations
i. Basis of Forced Draft Fan
ii. Basis of Induced Draft Fan
7. Vacuum Package
i. Study of Vacuum Pump
ii. Study of Ejectors
8. Process Control Valves
9. Flow meters
10. Treaters
11. Fuel Oil Blending
12. Project on Design Of Heat Exchanger

9. ESSAR Group Profile
ESSAR GROUP-PROFILE
Introduction to ESSAR:
Essar is one of the India’s largest corporate houses with leadership positions in the high
growth infrastructure sectors of steel, energy, power, communication, shipping, and
construction. It employs 730000 people in 50 locations in world wide.
The group takes pride in being a high performance multinational organization, providing
world class services and products. Manned by a highly efficient and dynamic team of
employees, the group is growing stronger every day. A committed corporate citizen, the
group provides unwavering support to the community as well as initiates various social and
ecological drives that have a positive impact on society.
All the groups investments have been consolidate under ESSAR global ltd. with eight sectors
holding compels:
 ESSAR steel holdings ltd.
 ESSAR power holdings ltd.
 ESSAR energy holdings ltd.
 ESSAR communication holdings ltd.
 ESSAR shipping & logistic ltd.
 ESSAR construction.
 ESSAR Oil ltd.
 ESSAR Projects.
ESSAR brand names include:
 Vodafone Essar
 Algoma Steel
It is headed by Chairman Shashi Ruia& Vice Chairman Ravi Ruia.
The group takes pride in being a high performance multinational organization, producing
world class services by a highly efficient and dynamic team of employees.
Mission:
To create value for us towards and stock holders in core manufacturing and service business,
through world class operating sanders, state of art technology and the positive attitude of our
people.

10. ESSAR Group Profile
Presence of ESSAR Global Ltd. In various sectors:

11. ESSAR Oil Ltd.
ESSAR OIL LIMITED
Introduction:
ESSAR OIL LIMITED (EOL), Refinery Division is a 20 MMTPA plant in Vadinar, 39 km from
Jamnagar, with an investment close to Rs.10 billion. The refinery is country’s second largest
refinery at single location. The refinery has significantly reduced the country’s reliance on
imports of middle distillate, LPG and Lead Free Gasoline.
ESSAR Refinery Process Units:

 Primary Processing Units
a. Crude Distillation Unit (CDU)
b. Vacuum Distillation Unit (VDU)
c. Saturated Gas Separation Unit (SGU)

 Bottom of the Barrel
a. Delayed Coker Unit (DCU)

 Conversion Units
a. Continuous Catalytic Reformer Unit (CCR)
b. Fluid Catalytic Cracking Unit (FCCU)
c. Isomerisation Unit (ISOM)
 Treating Units & Other Units
a. Vacuum Gas Oil Hydro treating Unit (VGO HDT)
b. Diesel Hydro treating Unit (DHDS, DHDT)
c. Naphtha Hydro treating Unit (NHT)
d. Kerosene Merichem Unit (KMU)

12. ESSAR Oil Ltd.
e. Gasoline Merichem Unit (GMU)
f. Saturated LPG Merichem Unit (LMU)
g. Unsaturated LPG Merichem Unit (UMU-1 & 2)

 Sulphur Recovery Block (SRB)
a. Sour Water Strippers (SWS)
b. Amine Regeneration Unit (ARU)
c. Sulphur Recovery Unit (SRU)

 Hydrogen Manufacturing Unit (HMU)

 OSBL (Outside Battery Limit) Units
These units support the above mentioned units and act as auxiliary units to the refinery
process
 Crude Oil Tank (COT)
 Product Intermediate Tank (PIT)
 Fuel Oil/Gas storage and system
 Fresh Caustic (20%) Supply
 Spent Caustic Treating System
 Chemical Sour Water
 Desalination/ Demineralizing Plant (DDU)
 Nitrogen System (NGU)
 Water Treating Facilities (WT)
 Flare System (FSF)
 Air generation facilities (AGF)
 Cooling Water Facilities (CWF)
 Firewater Facilities (FWF)
Refinery Units and their purpose:

Primary Processing Unit
Crude Distillation Unit (CDU):


13. ESSAR Oil Ltd.
 Capacity: 20MMTPA
 Primary Unit to separate different boiling point fractions such as LPG, Naphtha,
Kerosene, light and heavy gas oils, reduced crude oil etc.
 Distillation conducted at slightly higher than atmospheric pressure.
 Unit design for specific crude with flexibility to process a few other crudes.
Vacuum Distillation Unit (VDU):

 By operating the unit at reduced pressure the atmospheric residue from CDU is
processed to produce vacuum distillate for diesel product & blending, light vacuum gas
oil and heavy vacuum gas oil.

Conversion Unit
Fluidized Catalytic Cracking Unit (FCC):

 Capacity: 3.7 MMTPA
 Purpose: Catalytic cracking of vacuum gas oils or residues at high temperature to convert
them into useful light petroleum products.
 Fluidized catalytic bed with continuous regeneration of catalyst is used for reaction.
 Cracked products contain unsaturated and hence need further treatment.
Catalytic Reformer (CCR):

 Capacity: 0.9 MMTPA
 Purpose: To increase octane number of gasoline
 Produces reformate as main product and hydrogen as main byproduct
 Continuous regeneration type.
Isomerisation Unit (ISOM):

 Capacity : 0.7 MMTPA
 Purpose: To increase the Octane No. (MS quality EURO III)of the fractions by
converting them to isomers having branched chains and saturating the unsaturates
Delayed Coking Unit (DCU):

 Capacity: 6 MMTPA
 Purpose: To convert bottom of the barrel (VDU) in to valuable distillate.
 Coking occurs in the Reactor Drum.
 Coke removed by water jetting.

14. ESSAR Oil Ltd.
 Coke drums operation in batches.
 Naphtha, gasoil are other products.

Treating Units
Naphtha Hydrotreater (NHT):

 Capacity: 1.5 MMTPA
 Purpose: To produce clean hydrotreated feedstock to feed the reforming unit.
 Splits full range naphtha to light and heavy naphtha.
Diesel Hydro Treating Unit (DHDT):

 Capacity: 3.8 MMTPA
 Purpose: To reduce the sulfur content and to improve the Cetane Index of the sour diesel
oil coming from CDU/VDU. In addition to this de-nitrification, saturation of
olefin/aromatic component is also achieved
Kerosene Treating Unit (KMU):

 Capacity: 1900 MT/SD
 This unit treats heavy naphtha, light and heavy kerosene from CDU for Aviation Turbine
Fuel/SKO and Diesel product blending.
Gasoline Treating Unit (GMU):

 Capacity: 0.6 MMTPA
 This unit treats medium gasoline from FCCU and other gasoline cuts from CDU to
remove the sulphur contents and meet the required quality of product.
LPG Treating Unit (LMU):
 Capacity: 0.28 MMTPA
 This unit treats medium LPG from SGU to remove the sulphur contents using caustic
Sulphur Recovery Unit (SRU):

 Capacity: 2*220 TPD
 To recover elemental sulphur from the H2S obtained separated in various treating
units.
Vacuum gas oil HydrotreatingUnit (VGOHT):

15. ESSAR Oil Ltd.

 Capacity: 6.15 MMTPA
 Purpose: To remove sulphur and nitrogen along with the saturation of olefin and
aromatic component present in VGO from VDU.
 This is done in order to upgrade the quality of crude.
Diesel Hydro-desulphurization Unit (DHDS):
 Capacity: 5 MMTPA
 Purpose: Diesel Hydrodesulphurization unit is to reduce the Sulfur content of the
diesel product and meet the required market requirement.
Hydrogen Manufacturing Unit(HMU):
 Capacity: 130 kNm3/hr
 Purpose: To supply 99.9% pure hydrogen to the downstream Hydroprocessing
Units.
Produces Hydrogen via Steam Reforming.
Refinery off gas
LPG
Motor spirit
SKO/ATF
HSD
F.O.
Sulphur
SweetVGO
Pet Coke
Bitumen
Essar Oil Limited
ISBL-1 ISBL-2 ISBL-3
CDU VGOHT DCU
FCCU DHDS
SRU-1 DHDT
ARU-1 ISOM
Mini HMU
HMU SRU-2
NHT-CCR
OSBL and utilities
CRUDE

16. ESSAR Oil Ltd.

17. ESSAR Oil Ltd.
SAFETY IN REFINERY
Safety first, is the trend in any industry. The refinery is very accident prone area if dealt
with carelessness. Therefore many safety issues are concerned with industry.
Personal Protection Equipments (PPEs)
To avoid the above casualties the company provides some basic PPEs and gives basic
safety training to the people inside the refinery. This training includes basic MSDS knowledge,
fire training and other basic precautions to be taken care. Some of the common PPEs are:

Helmets
Safety Spectacles
Hand Gloves
Safety Shoes
Ear Plugs
Safety Equipments

 Beacons: There are a three light system. If there are any leakage of gas, lights are
flashing:
o Red-Fire
o Blue-Toxic Gas
o Yellow-Flammable Gas

 MCP: In a refinery there is a MCP, if any accident or fire occurs, then any worker or
employs
 Break the glass of MCP and location of breaking glass is shown in Fire Station Control
Room.

 Assembly Point: if any accident take place inside the refinery unit, every workers and
employees go to the assembly point where rescue operation take place after head count.

 Windsock Flag: This is a flag with red and white strip cloth, kept on the tall structure of
refinery. From this we know direction of wind. If any fire or explosion happens we must
go in perpendicular to the direction of wind.

 Hydrant Monitors and Deluge System

 DCP Extinguishers

18. ESSAR Oil Ltd.

 Hydrocarbon/Hydrogen/Toxic gas Detectors

 Safety Showers
General Safety Guidelines

 Smoking is strictly prohibited inside the refinery campus
 One should not carry cell phones in refinery area
 Only safety shoes are allowed in the refinery
 No woolen clothes that can produce static charge are allowed in the
refinery area
 Always follow the safety instructions of the work place
 Use PPE where has been told to
 Last but not the least always is aware while walking in the refinery area.

19. Crude Distillation Unit-2
(CDU-2)

20. General Considerations of CDU-2
 General considerations on CDU-2 (unit -02000):
 The main objective of Crude distillation unit-2 is to separate crude into different products by boiling
point differences. Different boiling range products are drawn from the main crude column. The
bottom product of crude column is further distilled in vacuum distillation column. Here distillation is
carried out under vacuum to separate high boiling fractions which cannot be easily separated under
atmospheric pressure.
 The design basis for CDU-2 is 100% Mangla crude.
 Some unique qualities of Mangla Crude – very low naphtha and jet/kerosene- it is ideal
crude for VBU conversion to CDU-2 (conversion from VBU).
Capacity:
 The capacity of crude distillation unit-2 is 2MMT/Year (6816m3
/day) (5998 MT/D).
 Turn down capacity of CDU-2 is 60% of design capacity.
 Total cycle time is 8000 hours/year minimum.
Some basis of CDU/VDU-2(unit 2000):
 Design basis crude blend of CDU-2 is 100% Mangla Crude oil from INDIA. Two cases were
developed.
o Case-1 – no Atmospheric Residue (AR) to FCCU, and
o Case-2 – 0.4 MTPA atmospheric residues to FCCU.
 In case-1 the entire atmospheric column is processed in vacuum unit... the HVGO cut-point is
reduced to 497C to stay within the vacuum tower diameter limit. For case 2 0.4 MTPA of
atmospheric residue is routed to FCCU while the balance of AR is routed to vacuum unit. While the
atmospheric residue is produced from Mangla crude is very paraffinic and low in sulphur it is well
suited for direct feed to FCCU. However, the nickel content is 112 ppm. Routing 0.4 MTPA to AR to
the FCCU will increase the metals on the total cat feed by 12 ppm.
 Crude is fractionated into various cuts like off gas, diesel & atmospheric residue. Diesel is cooled and
routed to storage or directly routed to hydro-treaters. Off gases are sent to FCCU/CDU-1. Naphtha is
stabilized by removing light component.
 The stabilized naphtha is routed to either FCCU or NHT or Storage.
 Atmospheric residue is routed to vacuum heater and subsequently to vacuum column for further
fractionation. HVGO produced is used either as FCCU feed or for blending with VR to produce low
sulphur fuel oil (LSFO).
 LP & MP stream is generated by exchanging heat to BFW from hot AR, HVGO & VR stream.
Stream produced is superheated in conversion zone of Vacuum heater routed to respective steam
header.

21. General Considerations of CDU-2
Basic Properties of Mangla Crude-
Sr. No. Parameters Value
1 Density @ 15C 876.7 kg/m3
2 Sp. Gravity @ 15.6C 0.8771
3 API 29.8
4 Sulfur (Wt %) 0.08
5 Total Acid No.(TAN) 0.41 mgKOH/gm
6 Nitrogen 2100 ppm (wt)
7 Carbon Residue (Wt %) 4.5
8 Pour Point 45 C
9 Viscosity @ 50C 59.13 CSt.
10 Salt 1PTB
11 Asphaltene (Wt %) <0.1
12 Metals: 1) Nickel 108 ppm (wt)
2) Vanadium 2.5 ppm (wt)
3) Iron 1ppm (wt)
4) Copper 0.4 ppm (wt)

22. General Considerations of CDU-2
Schematic of CDU-2
Off gases to FCCU
Naphtha to NHT feed tank
Diesel to DHDS/DHDT/ Diesel
Blending Tank
Atmospheric Residue (AR) to Vacuum Column/
FCCU
Crude
Distillation
Column
Mangla Crude

23. General Considerations of CDU-2
Vacuum Slop to DHDS/Storage Tank
Vacuum Distillate to DHDS/
Storage Tank
HVGO to VGO HT
Vacuum Residue (VR) to DCU/
HSFO Blending
Vacuum
Distillation
Column
AR

24. General Considerations of CDU-2
True Boiling Point Curve
 The composition of any crude oil sample is approximated by a true boiling point (TBP) curve.
 The method used is basically a batch distillation operation, using a large number of stages,
usually greater than 60, and high reflux to distillate ratio approximately greater than 5. The
temperature at any point on the Temperature- volumetric yield curve represents the true boiling
point of the hydrocarbon material present at given volume percent point distilled.
TBP Distillation Yield Data:
Sr. No. Fraction name Temperature C Yield wt%
1 Light gases + LPG -- ND
2 Sour Naphtha C5-95 0.3
3 Heavy Naphtha 95-135 1.1
4 Kerosene Swing 135-160 1.2
5 Light Kerosene 160-210 1.9
6 Kerosene Swing 210-245 2.3
7 Heavy Kerosene 245-270 2.8
8 Light Diesel 270-320 7
9 Heavy Diesel 320-355 5.9
10 RCO 355+ 77.5
11 Vacuum Distillate 355-380 4.8
12 VGO Swing 380-400 4.2
13 LVGO 400-425 5
14 HVGO 425-565 28.9
Product Yield Pattern
Case 1- No AR to FCCU
MMTPA m3
/hr TBP Cut
point (C)
Yield wt%
Crude 2.00 284.3
Off gas 0.0002 0 - 0.01
Naphtha 0.029 4.8 165 1.43
Diesel 0.407 62.5 350 20.33
AR to FCCU 0.0 0.0 - 0.0
Vacuum Distillate 0.065 9.9 368 3.27
Gas Oil 0.591 85.1 497 29.54
Vacuum Residue 0.909 122.0 497+ 45.42

25. General Considerations of CDU-2
Case-2 - 0.4 MMTPAAR to FCCU
 Product destination and specifications:
 Off gases from fractionators and stabilizer to be sent to FCCU wet gas compressor/ CDU-1
off gas compressor suction.
 Naphtha is sent to the Naphtha hydrotreater unit (NHT), to the FCC unit or storage.
 Vacuum slop is sent to either DHDS or wet slop.
 Diesel and Vacuum diesel to be sent to Diesel hydro de-sulfurization unit (DHDS) or Diesel
hydrotreater (DHDT) or storage or diesel blending.
 Heavy Vacuum Gasoil is sent to the Fluid Catalytic Cracking Unit (FCCU), storage or Low
Sulphur Fuel OIL (LSFO) blending.
 Power plant feed.
 Low sulphur fuel oil.
 Specifications applied to run down Products:
1. Naphtha
TBP Range C : C5-165
C4’s % wt : 0.5 maximum.
2. Diesel
TBP Range C : 165-350
ASTMgap Naphtha/Diesel, C : 5 minimum (for 95/5 %vol.)
Flash point (Abel) C : 66 Minimum
3. Vacuum Diesel
TBP Range C : 257-378
MMTPA m3
/hr TBP Cut
point (C)
Yield wt%
Crude 2.00 284.3
Off gas 0.0002 0 - 0.01
Naphtha 0.029 4.8 165 1.43
Diesel 0.407 62.5 350 20.33
AR to FCCU 0.4 55.4 - 19.99
Vacuum Distillate 0.049 7.4 368 2.44
Gas Oil 0.439 63.3 497 21.97
Vacuum Residue 0.677 90.9 497+ 33.83

26. General Considerations of CDU-2
Flash point (Abel) C : 68 Minimum
HeavyVacuum Gas Oil (HVGO)
TBP End Point C : 490
CCR % wt : 0.5% maximum
Metals (V+Ni) ppm wt : 20 maximum
4. Vacuum Residue (VR)
TBP end point C : 867
CCR % wt : 9.5 maximum
Metals (V+Ni) ppm wt : 200 maximum
5. Power Plant Feed
Sediment %wt : 0.25 maximum
6. Plant Fuel Oil
Viscosity CST : 20 at 200C, 85 at 150C
Sediment %wt : 0.25 maximum
7. Low Sulphur Fuel Oil (LSFO)
Flash point (Prenksy-Martins) C : 66 minimum
Sulphur % wt : 0.3% maximum (normal operation)
Viscosity CST : 140 at 50 C
Sediment %wt : 0.25 maximum

28. Flow Diagram

29. Process Description
Process Description:
 Pre- Desalter preheats Exchanger Train:
 Crude from Product intermediate tanks enters directly to 20E-101 A/B before
entering into desalter (020V- 111) at 60-70 C.
 Crude flow to the unit is controlled through 20FV-0132. Then crude is further
heated to 140C before entering into Desalter.
 Desalter pressure is controlled through cascade control with 20FV-132. Crude
temperature is increased up to 140C by exchanging heat with first diesel product
from diesel side stripper in 20E-101 A/B and then diesel pump around 20E -101
C/D.
 Split range control valves (20TIC-210 A) cold and hot diesel (20TIC-210A) pump
around controls desalter inlet temperature.
 Desalter:
 The purpose of desalter is to remove salt and sludge from crude. Desalting is
done in single stage. Wet crude is mixed with process water before 20E-101 A/B
heat exchanger train as well as before desalter and enters from the bottom of the
desalter.
 Crude and water along with de-emulsifier is mixed by mixing valve. Pressure drop
across mixing valve ensures the intimate mixing crude and water.
 Due to high voltage applied between the grids, water droplets dispersed in the
crude get charged and are attracted towards each other. Thus getting in bigger size
it drops down to the bottom of the desalter by gravity.
 Interface level is important in operating the desalter. High interface level may
cause short out of electrodes and water carry over along with desalted crude. Low
interface level may cause oil carry over along with brine. Desalter has 3 agar
probe level control system which measures crude water interface level, mud &
solids level and emulsion level below electric grid.
 Crude from desalter (20V-111) at 128C and 97 Kg/cm2
g pressure flows out
desalter top which goes to feed pump (20P-101 A/S) suction. Process water from
sour water stripper unit is preheated in exchanger 20E-106A/B/C/D to 88C with
brine from desalter (tube side) and mixed with the crude at the inlet of desalter.
The brine from (020V- 111) is re-circulated via mud wash circulation pump 20P-
112 and effluent is discharged after further cooling from 77C to 37C by sea

30. Process Description
cooling water in 20E- 108 A/B before sending it to waste water treatment unit
(8400 unit) or sour water stripper unit.
 Post-Desalter preheats Exchanger Train:
 Crude from desalter comes out from desalter top and goes to feed pump (20P-
101A/S) suction pump. Feed pump increases crude pressure from 9.5 kg/cm2
to
48 kg/cm2
g. Crude then enters directly to20E-101 E/F and subsequently heated
in tube side of 20E-E/f & J/K exchanger, VR in 20E- 101N/P & L/M and AR in
20E- 101Q/R exchanger before entering into crude heater (20F-101A). Crude
temperature is raised to 280-300C in post desalter exchanger train. Crude flow
to the heater is collected through pass flow control valves 20FV-006, 20FV-008,
20FV-010, and 20FV-012.
 Crude Furnace (20F- 101A):
 A crude furnace is vertical, box type with balanced draft and air pre-heater.
There are 4 nos. of duel fired burners. It has 4 passes in radiation and 4 passes in
convection section. Recuperative type air pre-heater is provided for preheating
the combustion air.
 Crude heater has been designed at capacity of 20MKcal/hr.

31. Process Description
 The hot feed is introduced in 4 passes of furnace 20F-101A at 280-300C. Feed
is heated to 360-365C which is required for fractionation operation to take
place. Separate flow control is provided for each furnace pass.
 Required outlet from furnace temperature is attained by firing control. For
accurate load on each furnace pass, coil balancing control system and for
accurate control of coil outlet temperature.
 Fuel-Air demand module has been provided in Distributed Control System
(DCS). The furnaces are designed for duel firing either by fuel gas or fuel oil.
The furnaces outlets from all the passes enter the atmospheric fractionation
column (20C-101) where fractionation operation takes place.
 Atmospheric column (20C 101):
 The main fractionator’s tower 20C-101 has 12 trays for fractionation and 9nos.
of stripping trays below flash zone. In addition with that one packed bed is
provided for washing above the flash zone and for steam stripping under the
flash zone. The tower operating pressure is 1.75lg/cm2
and temperature is
365C at the feed inlet.
 Medium pressure steam is injected at the bottom of flash zone (below stripping
trays) of the tower to strip the light hydrocarbons out of the heater effluent.
 The vapour entering in flash zone is washed by an induced reflux while passing
through the packed bed above the flash zone.

32. Process Description
 Above the washing section, a fractionation section packed bed is provided for
separation above (12 tray). Part of it is steam stripped in the side-stripper 20C-
102 and pumped by diesel pump 20P-114A/S to 20E-101A/B, where crude is
heated by exchanging heat with diesel. The pump around diesel is cooled by
heat exchanger preheat in 20E-101 C/D before it enters back to main
fractionators as cold reflux at top of pump around section (trays 9 to 11).
 Diesel side stripper 20C-102 is a column with 6 trays. Medium Pressure (MP)
steam is used for stripping of lighter components. The stripped out gases along
with the steam are sent back to atmospheric column at tray 9.
 The fractionator’s top section (trays 1 to 8) is a fractionation section for diesel-
naphtha separation. The overhead vapour is partially condensed in the
condensed 20EA- 101 and 20E-102, and then the liquid and vapour are
separated in reflux drum 20V-104. The vapour phase is routed, on pressure
control, to FCCU wet gas compressor or to CDU off Gas Compressor (outside
battery limit). Naphtha is the tower overhead line for protection against
corrosion by vapour acidity partially used as main fractionators to reflux and
the remaining part as feed for the downstream stabilizer column on flow
control. The reflux flow is controlled by temperature controller provided on the
overhead vapour line of atm. Tower.

33. Process Description
 A corrosion inhibitor and neutralizer are injected in the tower overhead line
for protection against corrosion by vapour acidity.
 Sour water is withdrawn from the reflux drum boot and pumped by 20P-105
A/S. One part of sour water is re-circulated to atmospheric overhead vapour
line and other part is sent to sour water stripper unit on boot level control for
further treatment outside battery limit.
 Naphtha Stabilizer Tower (20C-301):
 Un-stabilized naphtha is taken over from the atmospheric tower over from the
atmospheric tower reflux drum and heated against stabilized naphtha before
entering the stabilizer tower 20C-301.
 The naphtha stabilizer is a tray (30 trays) column used to separate the naphtha
and lighter fractions.
 A medium pressure steam re-boiled is provided at bottom of the column. The
stabilized naphtha is pumped by naphtha booster pump 20P-302. It is cooled
against the stabilizer feed in 20E 301 and by cooling water in 20E 304 and sent
to downstream NHT unit or to the FCC unit on flow control cascade with
stabilizer bottom level control.
 Overhead vapours are partially condensed in the water condenser 20E-303. The
liquid and vapour phase are separated in the reflux drum 20V 301. The vapour

34. Process Description
phase is routed, on pressure control, to the FCC wet gas compressor outside
battery limit along with the vapour from 20V-104 (atm. Reflux drum). The
total liquid phase is pumped by 20P-301 A/B as reflux, on flow control, back to
the tower; therefore there is no recovery. The level of the reflux drum is
controlled by controlling the cooling water flow rate to 20E 303.
 Vacuum Heater (20F-101B):
 A vacuum furnace is vertical box type with balanced draft and air pre heater.
There are 4 nos. of duel fired burners. It has 4 passes in radiation in
convection section. Recuperative type air pre heater is provided for preheating
the combustion air.
 Vacuum heater has been designed at capacity of 20MKcal/hr.
 The hot feed is introduced in 4 passes of furnaces 20F-101B at 340-350C.
Feed is given to increase fluid velocity inside the coil.
 Required outlet temperature from furnace is attained by firing control. For
accurate load on each furnace pass, coil balancing control system and for
accurate control of coil outlet temperature. Fuel- Air demand module has been
provided in distributed control system (DCS). The furnaces are designed for
duel firing either by fuel gas or fuel oil. The furnaces outlets from all the

35. Process Description
passes enter the vacuum fractionation column (20C-201) where fractionation
operation takes place.
 Medium pressure steam and low pressure steam generated in the unit are
superheated in the convection section of furnace before using as stripping
steam in the fractionation towers. The excess steam is sent to refinery steam
header under proper conditions.
 Steam-air decoking facility with pot is provided for vacuum heater.
 Vacuum Tower (20C-201):
 Atmospheric residue is sent for vacuum gasoil recovery to the vacuum flasher
20C-201. The vacuum flasher is a packed tower. Low pressure superheated
steam is injected into the bottom section of the tower to strip the light
hydrocarbons out of the vacuum residue and enhance the vacuum gasoil
recovery. A cold vacuum residue recirculation stream is injected at the bottom
of the tower to avoid any undesirable additional cracking by cooling bottom
liquid. Operating pressure of the tower is 70mm hg and operating temperature
is 395C at feed inlet zone.
 The entering vapour is washed by a vacuum gasoil reflux while passing
through a packed bed (bed 4) above the flash zone. The recovered liquid is
withdrawn on a total draw off tray and sent back as overflow to the stripping
section below.
 Above that washing section, two packing sections are provided for
fractionation and heat recovery (beds 3 and 2). The vacuum gasoil is
withdrawn on a total draw off tray below these sections and pumped by 20P-
202A/S. Part of it is used as liquid reflux to washing section.

36. Process Description
 One part of balance is cooled down by crude exchangers in, 20E-101E/F/J/K
an MP steam generation in 20E-202, BFW pre-heater 20E 103 and LP steam
generation in 20E 203 before entering back the vacuum flasher as pump
around stream on flow control. Remaining part of balance is routed to storage.
A filter 20FT 203 is provided in HVGO PA line to filter out any coke particles
carried along with.
 The top packing section (bed 1) is a pump around section where a vacuum
distillate is condensed. It is withdrawn on a total draw off tray and pumped by
20P 201A/S. It is used for pump around requirement, and also as reflux for the
sections below. A filter 20FT 204, 20FT 205 is provided in vacuum distillate
PA line to filter out any coke particles carried along with. In normal operation,
no light vacuum distillate is routed to storage but a connection is provided for
such recovery. The pump around LVGO flow rate is controlled by a flow
controller cascade with the level control of VD total draw off tray. A provision
is given to send a part of VD to storage along with diesel.
 Vacuum system for vacuum tower:
 The vacuum system creates the vacuum conditions required for the operation
of the vacuum tower.
 During normal operation, vacuum is obtained by routing the vacuum tower
overhead vapours through the vacuum system pre-condenser 20E-206X,
where they are cooled by exchanger with sea cooling water, the cooled

37. Process Description
vapours are routed to first stage vacuum ejectors 20J-201 A/B/SX (three 50%
duty ejectors, two normally in service =100% duty, one on standby). MP
steam is used for ejectors. Mixture of steam and hydrocarbon (H/C) vapours is
cooled in first stage condenser 20E-207X with cooling water. The liquids
condensed in first stage condenser are routed by gravity to vacuum condensate
accumulator 20V-201. The vapours from the top of first stage condenser,
together with vapours from the vacuum condensate accumulator, are fed
forward to second stage vacuum ejectors 20J-202A/B/X (one normally lined-
up ready for service, providing 60% capacity). The effluent is routed to second
stage condenser 20E-209X, where the heat from the stream is removed with
cooling water. From here the vapours are directed to third stage vacuum
ejectors 20J-203A/B/X (one normally lined-up ready for service, providing
40% capacity. Thus 2ND
+3RD
stage ejectors = duty of liquid ring pump). The
effluent is routed to 3Rd
stage condenser 20E-201X, where the heat from the
stream is removed with cooling water. From 3rd
stage condenser the vapours
are directed to un-condensable separators 20V- 203, in the same manner as
liquid ring separator vapours. Steam flow to the ejectors is automatically
started S part of the “liquid ring bypass system” (HS-054 action). When in
service, the condensate/oil levels in 2nd
and 3rd
stage condensers is routed,
under level control, to vacuum condensate accumulator 20V-201, for disposal
as in normal operation.
 In the event of activation of heater trip modulus (20UZ-101,201) the vacuum
system is provided with an in condensable safeguarding system (20UZ -017),
in which the flow of sour gas vapours to the CDU-2 heaters is isolated and
routed to flare (as per process scheme PS1265) or to atmosphere at safe
location together with LP dilution steam.
 Products Cooling and Heat Recovery:
 Vacuum residue pup 20P-203 feeds the residue to the preheat exchanger trains
(20E 101 L/M and N/P) for cooling to 250C by heating the crude oil. Coke
filters (20FT 201A/S) are provided at the upstream of pumps 20P-203 to
remove coke particles in the bottom of the vacuum flasher.
 A part of the cooled vacuum residue is used to atmospheric column quenching
and for vacuum flasher bottom quenching. The remaining part is cooled down
by medium pressure steam generation before being mixed with cutter oil to
achieve final oil specification. Or cooled vacuum residue is sent to storage or
Delayed coker Unit. Low sulphur Oil (ASFO) further cooled with tempered
water is provided for low sulphur fuel to be sent to storage.

38. Process Description
 Cooled vacuum gasoil out of 20E 203 is sent to downstream FCCU or cooled
with tempered water in HVGO cooler (20E- 101 G/H) before being sent to
storage.
 LP steam Generation:
 Low Pressure (LP) steam generated in 20E 203 (HVGO/BFW), 20E 104
(AR/BFW), 20E- 203(HVGO/BFW) is separated in LP steam separator 20V-
105. The steam is then sent to convection section of 20F-101B for
superheating. BFW is fed to 20V 104 on level controls. CBD and intermittent
blow down is sent to steam blow down drum (20V 106). The sour water from
20V 106 is pumped out by 20P 101 A/S to sour water system.
 LP steam from heater is superheated in 20BH 102 and sent to the header.
 MP Steam Generation:
 MP steam generated in 20E 202A/B (HVGO/BFW), 20E 201A/B (VR/BFW)
is separated in MP steam separator 20V 204. The steam is then passes through
convection section 20F 101B for superheating. MPBFW is fed to 20V-204 on
level controls. Intermittent blow down is routed to LP steam separator (20V
105).
 MP steam from heater is directed to de-super heater 20BH-101 and then to the
header.

39. Specifications of Major Equipments
Specifications of major equipments:
1. Atmospheric tower (20C 101):
 The atmospheric tower has total 21 (12 + 9 stripping) trays. Out of that 12 trays are
for fractionation. Above flash zone there is packed bed for fractionation of diesel and
atmospheric residue. Below flash zone there are 9 stripping trays.
 Trays 17 to 20 for washing above the flash zone and trays S1 to S9 for steam
stripping under the flash zone.
 A coke strainer is provided at the bottom of tower to trap coke particles carried with
the residue.
Operating Conditions:
Pressure (Kg/cm2
g) (top/bottom) : 1.7/2.1
Temperature (o
C) (top/bottom) : 124/406
Design Conditions: Kg/cm2
g o
C
Top 7580 mm : 5.3 250
Next 4820 mm : 5.4 320
Rest : 5.7 430
Material of Construction:
Top section (from top of tray 4) : CS+ AL 6XN 6mm
Top section (tray 4 to tray 12) : CS+ CA 6mm
Bottom section (from tray 12 to bottom) : CS+ Clad SS 304L
All internals : AL 6XN (up to tray 4) + SS.
Tray 1-8 Fractionation for Diesel & Naphtha
Tray 9-11 Diesel pump around
Tray 12 Total draw off tray of diesel
Packed bed Fractionation of diesel and atm. Residue
S1-S9 Stripping trays for lightest from AR
2. Diesel side stripper (20C 102):

40. Specifications of Major Equipments
 The purpose of side stripper is to strip out the lighter fractions from diesel cut of
atmospheric tower. The stripper has got 6 single pass trays.
 Feed is introduced to the column at the top tray through a 4” nozzle and the return
vapour is sent to atmospheric tower on tray 9. Stripped diesel is sent to pre-heat
exchanger train-1 (20E 101A/B) and air cooler 20EA 102 before routing to storage
tanks.
 MP steam (14.5kg/cm2
g, 200 o
C) is used for stripping purpose.
Operating conditions:
Operating pressure (Kg/cm2
g) : 1.95
Operating temperature (o
C) : 226
Design conditions:
Design pressure (Kg/cm2
g) : 5.5
Design temperature (o
C) : 275
Material of construction:
Shell and head : CS
Internals : SS
3. Naphtha stabilizer (20C 301):
 The purpose of this column is to separate the light fraction from un-stabilized naphtha
and to stabilize it.
 It has 30 single pass (valve tray) trays. Feed enters at tray 15.
Operating conditions:
Pressure (Kg/cm2
g) (top/bottom) : 6/6.3
Temperature (o
C) (top/bottom) : 56/171
Delta P (max.) (Kg/cm2
) : 0.3
Design conditions:
Pressure (Kg/cm2
g) (top/bottom) : 7.7/8

41. Specifications of Major Equipments
Temperature (o
C) : 200
Material of construction:
Shell and head : CS
Internals : SS
Tray and valve material : 11-13% Cr
 MP steam re-boiler (20E 302) is provided at the bottom of column. Stabilized
naphtha from column bottom is routed to FCC of NHT Unit or NHT Feed Tank after
exchanging heat with incoming feed.
4. Vacuum Tower (20C 201):
 Atmospheric residue from atmospheric tower is routed to vacuum tower through
vacuum heater for further fractionation.
 There are 4 packed beds, 3 sets of chimney trays.
 The hot atmospheric residue from vacuum heater (20F 101B) is introduced to flash
zone through 32” nozzle.
Operating conditions:
Operating pressure (mmHg a) (top/bottom) :60/70
Operating temperature (top/bottom) (C) :70/338
Design conditions: pressure (Kg/cm2 g) temp.(C)
Top 5800mm : 3.5 /full vacuum 230
Next 6350mm : 3.5 /full vacuum 320
Rest : 3.5 /full vacuum 430
Material of construction:
Shell and head : From top to bed 3= CS+CA 6
Rest : CS +304L SS clad
Grid type packing is provided. The packing material is 11-13% Cr.
Max. Delta P (mmHg) = 10.

42. Specifications of Major Equipments
5. LP steam separator (20V 105):
 The function of LP steam separator is to separate the steam from BFW, produced in
LP steam generators (20E 104,102,203).
 BFW is fed through level control from bottom. The steam is taken out by a 12” dia.
Pipe with closed end containing 450 holes (13 mm dia.) in staggered rows on top of
pipe.
 Vortex breakers are provided at the BFW outlet nozzle.
 Four alarms are provided for level in the vessel.
ALARM LEVEL in mm
HHLL 750
HLL 600
NL 460
LLL 150
Operating Conditions:
Pressure (Kg/cm2
) : 6.5
Temp.(C) : 167
Material of construction:
Shell & heads : CS
Internals : CS
6. MP steam separator (20V 204):
 The purpose of MP steam generator is to separate the steam from BFW, produced in
MP steam generators 20E 202 A/B, 201A/B.
 BFW is feed at level control from bottom. The steam is taken out by a 10” dia. pipe
with closed end containing 310 holes (13 mm dia.) in staggered rows on top of pipe.
 Vortex breakers are provided at the BFW outlet nozzles.
 Four alarms are provided for level.
ALARMS LEVEL in mm
HHLL 750
HLL 600
NL 530
LLL 150
Operating Conditions:

43. Specifications of Major Equipments
Pressure (Kg/cm2
) : 14.5
Temp. (C) : 199
Material of Construction:
Shell & heads : CS
Internals : CS

44. Details of Major Equipments
Details of Major Equipments:
General:
On both the atmospheric and vacuum column, the respective top temperature is controlled by
“Pump Around” Loops. The mass balance over the column top is maintained by controlling the
top product off take rate. Temperature at the bottom of the atmospheric column, the vacuum
column, and the diesel side stripper column is controlled by regulating the injection of
superheated steam.
The temperature of Naphtha stabilizer is controlled by regulating the reboiler heat input. The
atmospheric and vacuum columns have side products; the mass balance of each of these is
controlled by the off take rate. The heat balance of the side products is controlled by “Pump
Around” loops. The pressure of the vacuum column is created by a vacuum ejector package.
 Feed & Desalter (20PA-101):
 Crude oil from battery limit is pumped into pre-desalter trains of heat exchangers before
entering desalter. Crude flow at B.L. is regulated by 20FV-132 kept on crude inlet line
which takes the signal from 020PC-305 kept on desalter (020PA-101) outlet. At the inlet
of pre-desalter train of exchanger, Process water is injected into the crude. Process Water
is pumped through process water pumps (020P-111A/S) & the flow is controlled by
020FV-203. Provision has been kept if Process Water is unavailable then DM water shall
be used.
 The exit temperature of the wet crude leaving the heat exchanger 20E-101C/D is
controlled by split range 020TC-210. This is done by regulating the flow of atmospheric
pump around (PAR) via 020-TV-210A & bypassing 20E-101C/D comes down below
desired set point, then 020TC-210A starts to close and 020TC-210B starts to open.
 For proper separation inside desalter, process water needs to be mixed with crude. This
process water shall be catered through same pump, 020P-111A/S. The flow to crude is
regulated through 020FV-202. To improve mixing of heated crude with process water, a
pressure control valve is used upstream of the desalter (020PA-101). Controller (20PDC-
401) maintains a controlled pressure drop across the valve (20PDV-401) by regulating
the valve position directly ensuring better mixing. Desalter effluent from desalter is
cooled by stripped sour water in 20E-106A/B/C/D. The interface level in the desalter
vessel 20V-111 (20PA-101) is regulated by manipulation of the draw off flow rate. This
is controlled by regulating valve (20LV-201) through 20LC-201B.
 Crude heater (20F-101A):
 Crude from the desalter is pumped to crude heater via Feed Pump 20P-101A/S. The flow
is split to four parallel passes before entering the heater. The flow through each pass is
controlled by 20FC-001 to a set point calculated in Pass Balance Controller.
 Pass Balance Controller:

45. Details of Major Equipments
Basically Pass Balance Controller has two objectives:
 To control the flow to heater at desired value.
 To maintain the coil outlet temperature COT (final) temperature by adjusting the
individual pass outlet temperature.
 The fuel rate to furnace is adjusted to control a desired combined outlet temperature as a
part of the combustion control, which is separate from the Pass Balancing Controller.
 The coil outlet temperature (COT) of each pass is measured against the measured value
of the average COT. The difference between the average COT and individual COT (Tin)
then calculated.
 The flow is split to four parallel phases before entering the Heater. The flow through
each pass is individually controlled by 20FC-001 to a set point calculated in Pass Balance
Controller.
 Refer below schematic diagram for Crude Heater (20F-101A) Pass Balance Control
Schematic.
 Furnace firing control:
 The fuel rate to the furnace is adjusted to control a desired combined outlet temperature
as part of the combustion control, which is separate from the Pass Balancing Control.
 A temperature transmitter is provided on the common outlet of heater. The indication is
compared with set value and as per requirement; flow of FO or FG and proportionally
Air flow rate is changed. A selector switch is provided to choose between FO or FG and
proportionally Pressure Control on FO supply are provided. Hand control is provided on
FO return line for manually controlling the FO back pressure.
 Total heating of FO & FG is calculated from their flow rate and compared with the signal
from temp. Accordingly flow rate of air and FO/FG is adjusted.
 If it is required to lower down the fuel rate manually, first fuel flow is lowered and then
the air flow is adjusted and vice versa.
 Pressure control valve (PSV) is provided on pilot gas line to control gas pressure to pilot
burner. Flow of atomizing steam is controlled by PDC 198/211 on differential pressure
between FO supply & MP supply.
 Flow of air from bypass line to 20BC 102A (air pre-heater) is controlled according to
pre-heater outlet air temperature. Inside pressure (draft) in heater is controlled by
controlling the flue gas to stack by controlling the I.D. fan suction valve (PV050).
 Steam flow rate to the steam air pre-heater is controlled according to O/L temperature of
air by temperature controller TC 188.
 Atmospheric/ Crude Column:
The objective of Crude Column (20C-101) is to separate Crude into various products:
 Off Gas/Naphtha
 Diesel

46. Details of Major Equipments
 AR
Crude column consist of two sections namely Stripping and Rectification Section. In
Stripping Section, MP steam is injected in column. This will act as an aid in separation of
volatile components. The flow of MP steam is controlled by 20FV-052.
 Column Overhead (Off Gas/Naphtha):
 Overhead vapour from the top of the column is cooled in an air condenser 20EA 101.
The temperature leaving the air cooler is controlled by 20 TC-088 which adjusts the
speed of those fans fitted with variable pitch drives. Corrosion inhibitor (CI) and
Neutralizer Amine (NA) are injected into overhead line. NA helps in maintaining the
pH and CI prevents the corrosion. Injection of NA is with the help of MP steam. A
partially condensed overhead vapor enters the Crude column Reflux drum 20 V -104.
The reflux from drum (20V-104) is pumped via Atmospheric Tower Naphtha pump
(20P-102A/S) back to crude column (20C-101) as a reflux and to Naphtha Stabilizer
(20C 301) for further processing. The flow to both columns is regulated by interface
level controller (20LC 011). This shall be cascaded with 20FV-088. If the level in
drum decreases, the 20FV-088 shall close without affecting reflux.
 Corrosion Inhibitor (CI) is also injected into reflux line. This is used to prevent
corrosion. The sour water liquid level which is accumulated in the boot is controlled
by 20-LC-012 regulating valve 20LV- 012 and routing it to SWS Unit.
 Crude Column Pressure is controlled by 20PC-081. At normal conditions, Reflux
overhead (Off gas) from 20V-104 is club with overhead (Off gas) from 20V-301 and
sent either to UGS or CDU compressor. If somehow, the pressure in the line
increases then 20PV-301 and 20PV-147 open & excess pressure shall be routed to
flare.
 The boot i.e. Sour Water, of drum 20V-104 is split into 2 nodes and is pumped by
20P-105A/S:
a) One node (Wash water) is injected into inlet of cooler 20EA-101 to avoid
Corrosion. The injection is controlled by 20FV-206.
b) Another is sent to SWS Unit for further processing.
 Diesel draws off:
 Diesel from tray 12 to Crude column is sent to diesel stripper (20C-102). Level in the
chimney tray is controlled by 20LC-007 regulating the outlet flow rate via 20LV-007
the diesel stripper removes lighter components from the liquid stream using MP
steam. The flow of MP steam is controlled by 20FV-058. Diesel flow from diesel
side stripper shall be pumped to battery limit by pumps 020P-114A/S. The Hotter
diesel exchange its heat with crude in exchanger 20E-101A/B. Diesel is again passes
through an air cooler if it is to be routed to Storage.
 A 3 way Selector Switch (20HS-065) is provided which shall guide the flow of diesel
either to DHDT, DHDS, or storage. Using this switch an operator can route flow to

47. Details of Major Equipments
desired unit based upon downstream requirement. This Selector switch shall govern
the flow using valve 020FV-209 (on DHDS line), 20FV-081 (on storage line) &
20FV-080 (on DHDT line).
 Atmospheric tower pump around (ATPA):
 Same chimney tray, tray 12, is used for ATPA pump 20P-103A/S is split into 2
nodes:
a) One stream shall be used to heat Crude in the pre desalter train of exchanger
20E-101C/D. After exchanging the heat, it is routed back to crude column. The
flow is controlled by 20FC-049 and is regulated by 20FV-049.
b) Another stream shall be sent back to reflux column. The flow is controlled by
20FC-050 and is regulated by 20FV-050.
 Atmospheric Residue (AR):
 The bottom material in the crude is known as atmospheric residue. This is a feed to
vacuum column (20C-201). Either the whole AR is routed to vacuum column or 20%
of AR shall be sent to FCCU for further processing. A 2 way manual selector switch
(20HS-214) is provided which shall guide the flow of AR either to Vacuum Column
or FCCU. Using this switch an operator can route flow to desired unit based upon
downstream requirement. The discharge of the pump is split into 2 streams:
a) One sends either 100% AR to vacuum Column (20C-201) or 80% AR to 20C-201
through Vacuum Heater (20C-201) (when remaining needs to be sent to FCCU).
b) Another stream sends either 20% AR to B.L. (to FCC) via 20E-101Q/R & 20E-104 or
there shall be no flow. After getting heated in 20E-301, un-stabilized Naphtha is sent to
Stabilizer (20C-301) for stabilization.
 Stabilizer overhead:
 Stabilizer overhead is sent to stabilizer condenser (20E-303) for the removal of heat.
Temperature of naphtha across 20E-301 is controlled by 20TC-221 which in turn
controls the cooling water flow through 20TV-221. Corrosion inhibitor is injected in
Column overhead line to avoid corrosion.
 Bottom from Reflux Drum is sent back via pump 20P-301A/S to 20C-301 as a reflux.
The flow rate of reflux is controlled by cascading action of level controller 20LC-045
with 20FC-087. At normal conditions, Reflux overhead (off gas) from 20V-301 is
combined with overhead (Off gas) 20V-104 and sent either to UGS or CDU
compressor. If somehow, the pressure in the line increases then 20PV-147 and 20PV-
081 opens & excess pressure shall be routed to flare.
 Stabilizer Bottom:
The stabilized naphtha from stabilizer bottom is routed either to NHT or Storage. The
bottom is split in 2 nodes:

48. Details of Major Equipments
a) One is sent to stabilizer re-boiler 20E-302 which is heated and routed back to 20C-301
for stripping. MP steam is used as a heating media and flow is controlled by control
valve (20FV-086) which takes signal from 20TC-147 kept on column (20C-301).
b) Another stream is sent to NHT or storage via some exchangers namely 20E-301 where
energy is exchanged with feed (to column) and 20E-304 where cooling water is used to
lower the temperature. The flow is controlled by 20FV-089 which takes a signal 20LC-
043. Naphtha booster pump (20P-302) is installed to boost the flow to desired
destination.
 Vacuum Heater (20F-101B):
 Atmospheric Residue (AR) from Crude Column (20C-101) is pumped to Vacuum Heater
(20F-101B) via pump 020p-113A/S. The flow is split to four parallel passes before
entering the heater. The flow through each pass is individually controlled by 020FC-214
to a set point calculated in Pass Balance Controller.
 Pass Balance Control
Basically Pass Balance Controller has two objectives:
 To control the flow of heater at desired value.
 To maintain coil outlet temperature COT (final) temperature by adjusting the individual
pass outlet temperature.
 The fuel rate to the furnace is adjusted to control a desired combined outlet
temperature as part of the combustion control, which is separate from the Pass
Balance Control.
 The coil outlet temperature (COT) of each pass is measured against the measured
value of the average COT (20TI-079).
 Furnace Firing Control:
The fuel to the furnace is adjusted to control a desired combined outlet temperature as part of the
combustion control, which is separate from the Pass Balance Control.
 A temperature transmitter (20TI-079) is provided on the common outlet of heater. The
indication is compared with set value and as per requirement; flow of FO or FG and
proportionally Air flow rate is changed. A selector is provided to choose between control
on FO or FG. Pressure control in FO supply and FG supply are provided. Hand control is
provided on FO return line for manually controlling the FO back pressure.
 Total heating value of FO & FG is calculated from their flow rate and compared with the
signal from temp. Accordingly the flow rate of air and FO/FG is adjusted.
 If it is required to lower down the fuel rate manually, first the fuel flow is lowered and
then the air flow is adjusted. In case it is required to increase the fuel flow manually, first
the air flow is increased and then the fuel flow is changed.

49. Details of Major Equipments
 Pressure control valve PCV 195/208 is provided on pilot gas line to control gas pressure
to pilot burner. Flow of atomizing steam is controlled by PDC 198/211 on differential
pressure between FO & MP steam supply.
 Flow of air from bypass line to 20BC-102A (air preheater) is controlled according to
preheater outlet air temperature. Inside pressure (draft) in heater is controlled by
controlling the flue gas to stack by controlling I.D. fan suction valve (PV-050).
 Steam flow rate to steam air preheater is controlled according to O/L temperature of air
by temperature controller TC-188.
 Vacuum Column (20C-201):
 Vacuum column consist of two sections namely stripping and rectifying section. In
stripping section, LP steam is injected in column. This will act as an aid in separation of
remaining volatile components. The flow of LP steam flow is controlled by 20FV-062.
The objective of Vacuum Column (020C-201) is to convert AR into various products:
◊ Vacuum Diesel
◊ HVGO
◊ Vacuum Residue (VR)
 Vacuum column overhead:
 The vacuum in the column is maintained by ejectors system.
 Corrosion inhibitor (CI) and neutralizer amine (NA) are injected into overhead line. NA
helps in maintaining the pH and CI prevents the corrosion. Injection of NA is with the
help of MP steam.
 Vacuum system control:
 OVHD from 20C is condensed in vacuum system OVHD condenser 20E 206X by
cooling water (sea water) and enters the vacuum condensate accumulator 20V 201. PSV
105 is provided on SWR line (set: 6.5 kg/cm2 g) which discharge to drain.
 PSV 108 A/s are provided on 20v 201(set: 3.5 kg/cm2) which discharge to flare. Water
level in 20V 201 is controlled BT LC 022 regulating the flow of sour water to B.L (FC-
069)
 Level switch LS 023 is provided which stops or starts the vacuum system slop oil pumps
according to HH or LL level in 20V 201. Local level gauges LG 024, 025 and 026 are
provided to measure the drum levels.
 PSV 107(set: 6.5 kg/cm2 g), provided at the discharge of first stage condenser cooling
water outlet, which discharges to drain. LC 027 and LC 028 controls the level of
condensate in 20E 209X and 20E 210X respectively by controlling the flow of MP steam
condensate to 20V 201. Liquid ring bypass system 20KB 002 is provided for bypassing
the liquid pump when required.

50. Details of Major Equipments
 Flame arrestors 20FA 201A/B are provided in the line from 20V 203 to 20F 101A/B.
PDI 128 is provided which measures the differential pressure across the arrestors. Split
range level controller LC 032 is provided on 20V 201. IF level comes down LV 032A
operates and let the tempered water into the vessel.
 PSV 126 (set: 3.5 kg/cm2 g) is provided on 20V 203 which discharges to flare. A local
level gauge LG 033 is provided on 20V 203. LC 029 controls the liquid level in 20V
220X (liquid ring pump separator) by controlling draining to 20V 201. PSV 123A/S
provided on 20V 220X, which discharge to atm. At safe location. Level gauge LC 031
indicates level in 20V 202X.
 Automatic sequence
 Liquid ring pump bypass 20KB 002
 The sequence is activated by a switch button (20HS 054). It opens the isolation valves
around the second and third ejectors stages (20KV 002-1/002-2,002-3).
 HVGO DRAWOFF
A chimney tray, tray P2, is used in the Vacuum Column to provide a HVGO draw off. HVGO
Pump (20P-202A/S) shall be used for transferring HVGO to battery Limit.
The discharge of pump 20P-202a/s is split in to 3 nodes:
A) One stream shall be routed to battery limit via exchanger 20E-101J/K/E/F, 202 20E-103,
and 20E- 203. HVGO is used as a heating media for heating crude in exchanger 20E-
101J/K/E/F. Remaining heat shall be used for converting BFW to steam in exchanger
20E-203.
B) Last stream shall be sent back to vacuum column (above bed 4) as a pump around. The
flow is controlled by 20FC-208. A filter (20FT-203) has kept at outlet of 20FV-208 to
remove the undesired particles. This HVGO stream is used in AR to FCC case, to
maintain minimum HVG pump around flow for spray nozzle operation. HVGO Booster
Pump (20P-215A/S) is installed to increase the pressure of HVGO to meet the required
pressure at VGO-HT/FCCU or Storage. A 2 way manual selector switch (20HS-212) is
provided which shall guide the flow of HVGO either to FCCU/VGOHT or Storage.
Using this switch an operator can route the flow to desired unit based upon the
downstream requirement. The selector switch shall govern the flow by sending signal
from 20LC-019 (located at 20C-201) to 20FC-207 (located at FCC/VGOHT line) or
20FC-085 (storage). HVGO is passed through HVGO Cooler (20E-101G/H) while
sending to storage. Tempered water is used as a cooling media. The flow of tempered
water is controlled by 020TC-212 kept on outlet of 20E-101G/H.

51. Details of Major Equipments
 Vacuum Residue:
The bottom material of vacuum column is known as VR. VR pump (20P-203A/S) shall be used
for transferring VR to Coker unit or storage. The discharge of pump 20P-203A/s is sent to
desalted crude/VR exchanger (20E-101N/P/L/M) where it is heated with crude and then it is
separated into 2 streams. One stream is sent to 20C-201 for quench. The flow of quench is based
upon bottom temperature of column and is controlled by cascading temperature controller
(20TC-108) with 20FC-061. Another stream from downstream of 20E-101N/P/L/M shall be
routed either to cooker or storage. A 3 way manual selector switch (20HS-041) is provided
which shall guide the flow of VR either to cooker, fuel oil storage or VR storage. Using this
switch an operator can route to desired unit based upon downstream requirement. This selector
switch an operator can route flow to desired unit based upon downstream required this selector
switch shall govern the flow using 020FC-21 (Storage Line) and 20FC-211 (Coker line) and
20FC-130 (Fuel Oil via exchanger’s 20E-205A-F) based upon signal from 20LC-021. VR is
passed through Cooler (20E-212) while sending to storage. Tempered water is used as a cooling
media. The flow of tempered water is controlled by 20TC-214 kept on outlet of 20E-212.
 Vacuum Tower Pump around (VTPA):
A chimney tray, tray P1, is used in vacuum column to provide a VTPA draw off. Vacuum tower
pump around pump (20P-201A/S) shall be used for transmitting vacuum diesel back to column
and battery limit. The discharge of pump 20P-201A/S is split into 2 streams.
a) One stream shall be sent back to column as a reflux. The flow is controlled by 20FC-059.
b) Another stream is sent back to vacuum column as a reflux. If required, provision has
given to route some amount of Vacuum Diesel to battery limit. A manual selector switch
(20HS-042) is provided which shall divert some amount of Vacuum Diesel to Battery
Limit and remaining as reflux to column. This flow is controlled by cascading 20FV-064
(on battery limit line) withy sending to battery limit. The temperature is controlled by
20TC-109 (kept at outlet of cooler 20EA-201) which regulated the flow from 20TV-109.
 Steam Generation:
Steam generator (20V-105) is generating LP steam which shall be utilized for this
conversion. The feed to this generator is HP BFW (coming from battery limit). This is
done by passing AR & HVGO through AR/LP steam generator (20E-104) and
HVGO/LP steam generator (20E-203) respectively and producing LP Steam through
boiler feed water. Flow of HP BFW to vessel is controlled by 20FC-074 which cascades
with level controller 20LC-035. Steam Generator (20V-204) is generating NMP Steam
which shall be utilized for this conversion. The feed to this generator is MP BFW
(coming from Battery Limit). This is done by passing VR through VR/MP Steam
generator (20E-201A/B) and producing MP steam through the boiler feed water (BFW).

52. Details of Major Equipments
Flow of HP BFW to vessel is controlled by 20FC-078 which cascades with level
controller 20LC-040.
 Condensate injection:
BFW enters the drum on level control. A local level gauge (20LG-06) is provided on the
vessel. PSV 009 A/S (set: 5.2 kg/cm2
) provided on the top of the vessel which discharges
to the atmosphere at safe location. Pressure indicator 20PI-010 indicates the vessel
pressure at top. Split range control using Nitrogen gas is used for controlling the vessel
pressure. The discharge of split range control is to the atmosphere at safe location. Four
nos. of metering pumps 20P-106A/B/C/D feeds BFW to heater-B passes cross over. Each
pump feeds to two passes of. The pumps are provided with stroke adjustment facility.
PSV are provided at each discharge from the pump which discharges to the suction of
same pump.

53. Heater Operations
Heater Operations:
Introduction:
 CDU-2 has heaters 20F-101 A & B one is required to heat crude to fractionate into
diesel, naphtha and off gases. In addition with that other heater is to heat atmospheric
residue to fractionate into vacuum diesel and heavy vacuum gas oil. Each furnace has
independent fuel firing with FD/ID & APH system. Furnaces are rectangular box
type and four process flow
 Each pass enters in convection top section and leaves from the Shock section.
Convection tubes are having studded fins and the Shock tubes in the Convection
section have no fins.
 The radiant section tubes are arranged around four vertical rows and in a single row
across the width of the box, effectively forming four cells within the fire box. The
wall tubes are single fired, whilst those running across the width of the box are
double fired i.e. they have burners on both side.
 The convection tubes are across the top of the radiant box on a north south axis, and
are arranged on triangular pitch. The convection bank is raised above the fire box
arch to accommodate the radiant tube supports.
 The flue gases are fed from the fire box to underside the convection section by four
ducts one for each cell. The heater charge stream is divided into four parallel streams
per furnace with flanged inlet and outlet connections.
 In addition to heater B charge coils the convection section is also provides with two
super heater coils, one for medium pressure and one for low pressure steam.
 The furnace is also designed to operate at 100% of its design duty with only the FD
fans in operation i.e. with air pre-heaters and ID fan bypassed. Two FD fans and one
ID fans are available. The FD fans will normally operate in parallel, but are sized
such that total combustion air requirement of the furnace can be delivered as a single
unit.
 Oxygen Analyzer is provided in the Shock tubes area to analyze the correct
percentage of excess air from the flue gas coming out from the Radiant furnace
section. NOx and SOx analyzers are provided in the common stack.
 There are total numbers of tubes per pass. After heating to about 365C in crude
heater, all 4 pass radiation outlets meet a common header called transfer line.
Similarly for vacuum heater 54 numbers of tubes per pass is there and after heating
up to 430C radiation outlet meets common transfer line.
 Above the process fluid convection coils, MP steam generated from MP steam vessel
20V-204 is superheated in the MP steam super heater coils. Also, LP steam generated
from LP steam vessel 20V-105 is superheated in the LP steam super heater coils.
There are total eight number tubes per pass. For LP steam there are total four

54. Heater Operations
numbers of passes and for MP steam there are three numbers of passes. There are
total eight soot blowers provided in each heater for the scoot blowing purpose.
Heater-A Coils Details
Process Coils MP Steam Coils LP Steam Coils
Radiation Section
No. Of Passes 4 0 0
No. Of Tubes/Pass 56 0 0
Total Tubes 224 0 0
Convection Section
No. Of Passes 4 0 0
No. Of Tubes/Pass 15 0 0
Total Tubes 90 0 0
No. Of F.G Burners 4
No. Of F.O Burners 4
No. Of Retractable Scoot Burners 8
Heater-B Coils Details
Process Coils MP Steam Coils LP Steam Coils
Radiation Section
No. Of Passes 4 0 0
No. Of Tubes/Pass 54 0 0
Total Tubes 214 0 0
Convection Section
No. Of Passes 4 0 0
No. Of Tubes/Pass 21 0 0
Total Tubes 84 24 32
No. Of F.G Burners 4
No. Of F.O Burners 4
No. Of Retractable Scoot Burners 8

55. Heater Operations
Basis of Draft Fans:
The difference between atmospheric pressure and the pressure existing in the furnace or flue gas passage of a
boiler is termed as draft. Draft can also be referred to the difference in pressure in the combustion chamber area
which results in the motion of the flue gases and the air flow.
1. Natural Draft Fans: When air or flue gases flow due to the difference in density of the hot flue gases and
cooler ambient gases. The difference in density creates a pressure differential that moves the hotter flue gases
into the cooler surroundings.
2. Forced draft Fans: When air or flue gases are maintained above atmospheric pressure. Normally it is done
with the help of a forced draft fan.
3. Induced draft Fans: When air or flue gases flow under the effect of a gradually decreasing pressure below
atmospheric pressure. In this case, the system is said to operate under induced draft. The stacks (or chimneys)
provide sufficient natural draft to meet the low draft loss needs. In order to meet higher pressure differentials,
the stacks must simultaneously operate with draft fans.
4. Balanced draft Fans: When the static pressure is equal to the atmospheric pressure, the system is referred
to as balanced draft. Draft is said to be zero in this system.
Our heater is a Balance Draft so, we are using two types of fans: 1) Forced Draft Fans.
2) Induced Draft Fans.
 Purpose of using Forced Draft Fans:
 Forced Draft (FD) fans purpose is to provide a positive pressure to a system. Draft
is obtained by forcing air into the furnace by means of a fan (FD fan) and
ductwork. This basic concept is used in a wide variety of industries but the term
FD Fans is most often found in the boiler industry. Air is often passed through an
air heater; which, as the name suggests, heats the air going into the furnace in
Type of Draft
Fans
Natural Draft
Fans
Forced Draft
Fans
Induced Draft
Fans
Balanced Draft
Fans

56. Heater Operations
order to increase the overall efficiency of the boiler. Inlet or outlet dampers are
used to control the quantity of air admitted to the furnace and maintain the system
pressure.
 In forced draft cooling fans, air is "pushed" through the tower from an inlet to an
exhaust. A forced draft fan is a blow-through arrangement, where a blower type
fan at the intake forces air through the tower.
 Purpose of using Induced Draft Fans:
 Induced Draft (ID) fans are used to create a vacuum or negative air pressure in a
system or stack. Our centrifugal blowers are used to maintain elevated ventilation,
resulting in increased system efficiency. Twin City Fan can also supply extractor
fans, which are typically heavy duty construction to handle particulate in the
airstream. In the boiler industry ID Fans are often used in conjunction with FD
fans to maintain system pressure which is slightly lower than ambient.
 An induced draft mechanical draft fan is a draw-through arrangement, where a fan
located at the discharge end pulls air through tower. The fan induces hot moist air
out of the discharge end. This produces low entering and high exiting air
velocities, reducing the possibility of recirculation in which discharged air flows
back into the air intake.
 In general though, the choice between forced draft and induced draft is based on the
system is - if you have leaks, it is better to use ID, as FD will cause product loss.
Outside view of Draft FansInside view of Draft Fans

57. Heater Operations
Heaters dry out:
 Furnace dry out is carried out for curing furnace refectory before starting the
furnace. Burners and control system are also checked during this period.
 Initially the moisture will be evaporated from the area near the flame. But there
will be the moisture inside the refectory which has to be removed.
 Due to long exposure to heat the moisture inside the refectory will also be
removed.
 For confirmation, the shell temperature should be maintained at 100C.
 Steam is circulated through heater coil (for temperature above 200C) to prevent
damage to coils due to overheating.

58. Vacuum Package
Vacuum Package:
Introduction:
Vacuum package is used to create the required vacuum in CDU-2 vacuum column (20C-201).
Package contains three numbers of ejector stages and one liquid ring pump.
It creates vacuum by either of the following two ways:
1) Using first stage ejectors and liquid ring pump on line.
2) Using multi stage ejectors (i.e. all three stages of ejectors are in line & liquid ring
pump not in line).
 There are total seven ejectors (using MP steam as a motive fluid) three in first stages
two in second and third stage each.
 All condensate from condensers are collected into vacuum condensate accumulator
(20V-201), in which the sour water and hydrocarbon part is separated. Sour water is
pumped to B/L by using sour water pump 20P-204A/S. Hydrocarbon liquid is
pumped to wet slop tank by using vacuum system slop oil pumps 20P-205A/S.
Incondensable vapours generated in this system goes to crude heater from
incondensable separator vessel (20V-203).
Vacuum system pre-condenser 20E-206X:
Sea cooling water is used for cooling.
1. First stage vacuum ejectors (20J-201 AX/BX/SX):
There are three 50% duty ejectors two normally in service i.e. 100% duty, one on standby.
MP steam is used for ejectors as a motive fluid having 12Kg/cm2
g pressure and 240C
temperatures.
a) First stage condenser (20E-207X):
Floating head type, 1-2 shell and tube heat exchanger
Sea cooling water.
2. Second stage ejectors (20J-202AX/BX):
One normally in line, providing 60% capacity
b) Second stage condenser (20E-209X):
PSV’s are provided on shell side inlet line of 20E-209X with 3.5 Kg/cm2
g set pressure.

59. Vacuum Package
3. Third stage vacuum ejectors (20J-203AX/BX):
One normally in line, providing 40% capacity
Thus Second + Third stage ejectors = Duty of the liquid ring pump.
c) After condenser 20E-210X:
Floating heat type, 1-2 shell and tube heat exchanger
PSV’s are provided on shell side inlet line of 20E-210X with 3.5 Kg/cm2 g set pressure.
PSV’s are provided on the sea water return line of each condenser with 10 Kg/cm2 g set
pressure. There is no separate supply of fresh sea cooling water to inlet condensers and after
condense, supply is given from the sea water return line of pre-condenser (20E-206X). Back
flushing arrangement is provided for each condenser.
Operating Principle:
Vacuum pump:
 The main functional assemblies of vacuum pump consist of rotor and a shaft turned
by an external an electric motor. The eccentric rotor lies within a chamber that is
formed by the casing of a body. Liquid compress-ant (water), refined to as seal liquid
is sent to the chamber from inlet. The motion of the liquid being rotated in the pump
operates as a compressing for the gas in the pump.
 In addition the liquid compressing fills the rotor chamber completely. The centrifugal
force emptied rotor chamber and force liquid compressing toward body casing. Due to
which a low pressure is generated and chamber draws gases through inlet port. Due to
eccentricity of rotor body casing, liquid compressing is forced back towards centre of
rotor chamber. Due to this, gas is compressed by converging liquid compressing and
the mixture of liquid compressing and compressed gas, then, discharges through the
pump discharge port.
Ejector:
Ejector is one of the most efficient vacuum generation systems having minimum maintenance
because of no rotary parts. Vacuum is being created by converting pressure energy into
kinetic energy by expanding steam through a nozzle at a supersonic velocity.

60. Vacuum Package
Principle of Ejector: It works on the principle of Bernoulli’s Equation:
Where
Basis Considerations:
 An ejector, steam ejector is a type of pump that uses the Venturi effect of
a converging-diverging nozzle to convert the pressure energy of a motive fluid
to velocity energy which creates a low pressure zone that draws in and entrains a
suction fluid. After passing through the throat of the injector, the mixed fluid expands
and the velocity is reduced which results in recompressing the mixed fluids by
converting velocity energy back into pressure energy. The motive fluid may be a
liquid, steam or any other gas.
 The Venturi effect, a particular case of Bernoulli's principle, applies to the operation
of this device. Fluid under high pressure is converted into a high-velocity jet at the
throat of the convergent-divergent nozzle which creates a low pressure at that point.
The low pressure draws the suction fluid into the convergent-divergent nozzle where
it mixes with the motive fluid.
2 2
1 1 2 2
1 2
1 22 2
P V P V
z z
g g g g 
    

61. Vacuum Package
In supersonic condition fluid (steam) behaves opposite to the continuity equation.
Q = V*A
Where, Q – Mass flow rate
V – Velocity
A – Area
 Due to which at the nozzle discharge, the area through the area is being increased
velocity increases and pressure energy decreases in suction chamber and this low
pressure region sucks vapour. The resulting mixture enters the diffuser where velocity
is converted to pressure at the ejector discharge.
 In multistage ejector the total amount of compression is divided between ejectors in
series. The ejector into which gases first enters is called first stage ejectors and
subsequent ejectors numbered in succession as second and third stage ejectors.
 Mixture of steam and H/C gases enters first stage condenser where condensable gases
and steam are condensed. Subsequent stages then compress only these gases which
are incondensable.
 Condensers between stages are called inter condensers.
 Condensers at discharge of the final stage is known as after condensers operates at
atmospheric pressure and is provided with a vent to allow the air and incondensable
gases to escape.

62. Vacuum Package
Process Description:
Using multistage ejectors (i.e. all three stages of ejectors are in line & liquid ring
pump not in line).
 In this case vacuum in the vacuum column is being created by using multistage
ejectors i.e. all three stages of ejectors are in line, which maintains vacuum column
bottom and top pressure, 70 mmHg and 60mmHg respectively.
 During normal operation, vacuum is obtained by routing the vacuum column
overhead vapours through the vacuum system pre-condenser 20E-206X.
 The cooled vapours are routed to first stage vacuum ejectors 20J-201 AX/BX/SX.
 Mixtures of steam and hydrocarbon vapours are cooled in first stage condenser 20E-
207X.
 The liquids condensed in the first stage condenser are routed by gravity to vacuum
condensate accumulator 20V-201.
 Incondensable vapours outlet from first stage condenser (20E-207X) is routed to
second stage ejectors (20J-202AX/BX).
 The effluent from second stage ejectors is routed to second stage condenser 20E-
203AX/BX.
 Third stage ejectors are always in line with second stage ejectors. The effluent is
routed to after condenser 20E-210X. From third stage condenser the vapours are
directed to incondensable separator 20V-203, in the same manner as liquid ring
separator vapours.

63. Process Control Valves
Process Control Valves
Process Control:
Process Control is an engineering discipline that deals
with architectures, mechanisms and algorithms for maintaining the output of a
specificprocess within a desired range. Process control is extensively used in industry and
enables mass production of consistent products from continuously operated processes such as
oil refining, paper manufacturing, chemicals, power plants and many others. Process control
enables automation, by which a small staff of operating personnel can operate a complex
process from a central control room.
Process control may either use feedback or it may be open loop. Control may also be
continuous (automobile cruise control) or cause a sequence of discrete events, such as a timer
on a lawn sprinkler (on/off) or controls on an elevator (logical sequence).
A thermostat on a heater is an example of control that is on or off. A temperature sensor turns
the heat source on if the temperature falls below the set point and turns the heat source off
when the set point is reached. There is no measurement of the difference between the set
point and the measured temperature (e.g. no error measurement) and no adjustment to the rate
at which heat is added other than all or none.
Types of Processes using process control:
 Discrete – Found in many manufacturing, motion and packaging applications. Robotic
assembly, such as that found in automotive production, can be characterized as discrete
process control. Most discrete manufacturing involves the production of discrete pieces
of product, such as metal stamping.

64. Process Control Valves
 Batch – Some applications require that specific quantities of raw materials be combined
in specific ways for particular durations to produce an intermediate or end result. One
example is the production of adhesives and glues, which normally require the mixing of
raw materials in a heated vessel for a period of time to form a quantity of end product.
Other important examples are the production of food, beverages and medicine. Batch
processes are generally used to produce a relatively low to intermediate quantity of
product per year (a few pounds to millions of pounds).
 Continuous – Often, a physical system is represented through variables that are smooth
and uninterrupted in time. The control of the water temperature in a heating jacket, for
example, is an example of continuous process control. Some important continuous
processes are the production of fuels, chemicals and plastics. Continuous processes in
manufacturing are used to produce very large quantities of product per year (millions to
billions of pounds).
 Applications having elements of discrete, batch and continuous process control are
often called hybrid applications.
Control Valves:
 Control valves are valves used to control conditions such
as flow, pressure, temperature, and liquid level by fully or partially opening or closing
in response to signals received from controllers that compare a "setpoint" to a
"process variable" whose value is provided by sensors that monitor changes in such
conditions.
 Process plants consist of hundreds, or even thousands, of control loops all networked
together to produce a product to be offered for sale. Each of these control loops is
designed to keep some important process variable such as pressure, flow, level,
temperature, etc. within a required operating range to ensure the quality of the end
product. Each of these loops receives and internally creates disturbances that
detrimentally affect the process variable, and interaction from other loops in the
network provides disturbances that influence the process variable.
 To reduce the effect of these load disturbances, sensors and transmitters collect
information about the process variable and its relationship to some desired set point.

65. Process Control Valves
A controller then processes this information and decides what must be done to get the
process variable back to where it should be after a load disturbance occurs. When all
the measuring, comparing, and calculating are done, some type of final control
element must implement the strategy selected by the controller.
Principles of Operation
 The most common final control element in the process control industries is the control
valve. The control valve manipulates a flowing fluid, such as gas, steam, water, or

66. Process Control Valves
chemical compounds, to compensate for the load disturbance and keep the regulated
process variable as close as possible to the desired set point.
 Control valves may be the most important, but sometimes the most neglected, part of
a control loop. The reason is usually the instrument engineer's unfamiliarity with the
many facets, terminologies, and areas of engineering disciplines such as fluid
mechanics, metallurgy, noise control, and piping and vessel design that can be
involved depending on the severity of service conditions.
 Any control loop usually consists of a sensor of the process condition, a transmitter
and a controller that compares the "process variable" received from the transmitter
with the "set point," i.e., the desired process condition. The controller, in turn, sends a
corrective signal to the "final control element," the last part of the loop and the
"muscle" of the process control system. While the sensors of the process variables are
the eyes, the controller the brain, then thefinal control element is the hands of the
control loop. This makes it the most important, alas sometimes the least understood,
part of an automatic control system. This comes about, in part, due to our strong
attachment to electronic systems and computers causing some neglect in the proper
understanding and proper use of the all important hardware.
What is a Control Valve?
 Control valves automatically regulate pressure and/or flow rate, and are available for
any pressure. If different plant systems operate up to, and at pressure/temperature
combinations that require Class 300 valves, sometimes (where the design permits), all
control valves chosen will be Class 300 for interchange-ability. However, if none of
the systems exceeds the ratings for Class 150 valves, this is not necessary.
 Globe valves are normally used for control, and their ends are usually flanged for ease
of maintenance. Depending on their type of supply, the disk is moved by a hydraulic,
pneumatic, electrical or mechanical actuator. The valve modulates flow through
movement of a valve plug in relation to the port(s) located within the valve body. The
valve plug is attached to a valve stem, which, in turn, is connected to the actuator.

67. Process Control Valves
Types of Control Valves:
1. Gate Valve:
 The gate valve, also known as a sluice valve, is a valve that opens by lifting a
round or rectangular gate/wedge out of the path of the fluid. The distinct feature of
a gate valve is the sealing surfaces between the gate and seats are planar, so gate
valves are often used when a straight-line flow of fluid and minimum restriction is
desired. The gate faces can form a wedge shape or they can be parallel. Gate
valves are primarily used to permit or prevent the flow of liquids, but typical gate
valves shouldn't be used for regulating flow, unless they are specifically designed
for that purpose. Because of their ability to cut through liquids, gate valves are
often used in the petroleum industry. For extremely thick fluids, a specialty valve
often known as a knife valve is used to cut through the liquid. On opening the gate
valve, the flow path is enlarged in a highly nonlinear manner with respect to
percent of opening. This means that flow rate does not change evenly with stem
travel. Also, a partially open gate disk tends to vibrate from the fluid flow. Most
of the flow change occurs near shutoff with a relatively high fluid velocity causing
disk and seat wear and eventual leakage if used to regulate flow. Typical gate
valves are designed to be fully opened or closed.[2]
When fully open, the typical
gate valve has no obstruction in the flow path, resulting in very low friction loss.
 Gate valves are characterised as having either a rising or a nonrising stem. Rising
stems provide a visual indication of valve position because the stem is attached to
the gate such that the gate and stem rise and lower together as the valve is
operated. Nonrising stem valves may have a pointer threaded onto the upper end
of the stem to indicate valve position, since the gate travels up or down the stem
on the threads without raising or lowering the stem. Nonrising stems are used
underground or where vertical space is limited.

68. Process Control Valves
2. Ball Valve:
 A ball valve is a valve with a spherical disc, the part of the valve which
controls the flow through it. The sphere has a hole, or port, through the middle
so that when the port is in line with both ends of the valve, flow will occur.
 When the valve is closed, the hole is perpendicular to the ends of the valve,
and flow is blocked. The handle or lever will be in line with the port position
letting you "see" the valve's position. The ball valve, along with the butterfly
valve and plug valve, are part of the family of quarter turn valves.

69. Process Control Valves
 Ball valves are durable and usually work to achieve perfect shutoff even after
years of disuse. They are therefore an excellent choice for shutoff applications
(and are often preferred to globe valves and gate valves for this purpose). They
do not offer the fine control that may be necessary in throttling applications
but are sometimes used for this purpose.
 Ball valves are used extensively in industrial applications because they are
very versatile, supporting pressures up to 1000 bar and temperatures up to
752°F (500°C) depending on the ball valve design and material. Sizes
typically range from 0.2 to 48 inches (0.5 cm to 121 cm). They are easy to
repair and operate.
1) Body 2) Seat 3) Disc (ball) 4) Handle (Lever) 5) Stem
3. Globe Valve:
 A globe valve, different from ball valve, is a type of valve used for
regulating flow in a pipeline, consisting of a movable disk-type element and a
stationary ring seat in a generally spherical body.
 Globe valves are named for their spherical body shape with the two halves of
the body being separated by an internal baffle. This has an opening that forms
aseat onto which a movable plug can be screwed in to close (or shut) the

70. Process Control Valves
valve. The plug is also called a disc or disk. In globe valves, the plug is
connected to a stem which is operated by screw action using a handwheel in
manual valves. Typically, automated globe valves use smooth stems rather
thanthreaded and are opened and closed by an actuator assembly.
 Globe valves are used for applications requiring throttling and frequent
operation. For example, globe valves or valves with a similar mechanism may
be used as sampling valves, which are normally shut except when liquid
samples are being taken. Since the baffle restricts flow, they are not
recommended where full, unobstructed flow is required.

71. Process Control Valves
4. Needle Valve:
 A needle valve is a type of valve having a small port and a threaded, needle-shaped
plunger. It allows precise regulation of flow, although it is generally only capable of
relatively low flow rates.
 A Needle Valve uses a tapered pin to gradually open a space for fine control of flow.
The flow can be controlled and regulated with the use of a spindle. A needle valve has
a relatively small orifice with a long, tapered seat, and a needle-shaped plunger on the
end of a screw, which exactly fits the seat.

72. Process Control Valves
 As the screw is turned and the plunger retracted, flow between the seat and the
plunger is possible; however, until the plunger is completely retracted the fluid flow is
significantly impeded. Since it takes many turns of the fine-threaded screw to retract
the plunger, precise regulation of the flow rate is possible.
 The virtue of the needle valve is from the vernier effect of the ratio between the
needle's length and its diameter, or the difference in diameter between needle and
seat. A long travel axially (the control input) makes for a very small and precise
change radially (affecting the resultant flow).
 Needle valves may also be used in vacuum systems, when a precise control of gas
flow is required, at low pressure, such as when filling gas-filled vacuum tubes, gas
lasers and similar devices. Needle valves are usually used in flow metering
applications, especially when a constant, calibrated, low flow rate must be maintained
for some time, such as the idle fuel flow in a carburetor.
 Since flow rates are low and many turns of the valve stem are required to completely
open or close, needle valves are not used for simple shutoff applications.
 Small, simple needle valves are often used as bleed valves in water heating
applications.

73. Flow meters
Flow meters
Introduction:
Flow measurement is the quantification of bulk fluid movement. Measuring the flow of
liquids is a critical need in many industrial plants. In some operations, the ability to conduct
accurate flow measurements is so important that it can make the difference between making a
profit and taking a loss. In other cases, inaccurate flow measurements or failure to take
measurements can cause serious (or even disastrous) results.
With most liquid flow measurement instruments, the flow rate is determined inferentially by
measuring the liquid's velocity or the change in kinetic energy. Velocity depends on the
pressure differential that is forcing the liquid through a pipe or conduit. Because the pipe's
cross-sectional area is known and remains constant, the average velocity is an indication of
the flow rate. The basic relationship for determining the liquid's flow rate in such cases is:
Q = V x A
where
Q = Liquid flow through the pipe
V= Velocity of Fluid through pipe
A= Area of Flow available for fluid
Other factors that affect liquid flow rate include the liquid's viscosity and density, and the
friction of the liquid in contact with the pipe. Also, the performance of flowmeters is also
influenced by a dimensionless unit called the Reynolds Number. It is defined as the ratio of
the liquid's inertial forces to its drag forces.
Types of Flow
meters
Pressure
based type
Flow Meters
Inferential
type flow
meters
Venturi Flow
meters
Orifice Flow
meters
Mechanical
type Flow
Meters
Variable area
flow meters
(Rotameters)
Electrical type
Flow Meters
Positive
displacement
flow meters
(Rotameters)

74. Flow meters
Differential Pressure Meters:
Pressure based meters:
 There are several types of flow meter that rely on Bernoulli's principle, either by
measuring the differential pressure within a constriction, or by measuring staticand
stagnation pressures to derive the dynamic pressure.
 The use of differential pressure as an inferred measurement of a liquid's rate of flow is
well known. Differential pressure flowmeters are, by far, the most common units in
use today. Estimates are that over 50 percent of all liquid flow measurement
applications use this type of unit.
 The basic operating principle of differential pressure flowmeters is based on the
premise that the pressure drop across the meter is proportional to the square of the
flow rate. The flow rate is obtained by measuring the pressure differential and
extracting the square root.
 Differential pressure flowmeters, like most flowmeters, have a primary and secondary
element. The primary element causes a change in kinetic energy, which creates the
differential pressure in the pipe. The unit must be properly matched to the pipe size,
flow conditions, and the liquid's properties. And, the measurement accuracy of the
element must be good over a reasonable range. The secondary element measures the
differential pressure and provides the signal or read-out that is converted to the actual
flow value
Orifice Flow meters:
 Orifices are the most popular liquid flowmeters in use today. An orifice is simply a
flat piece of metal with a specific-sized hole bored in it. Most orifices are of the
concentric type, but eccentric, conical (quadrant), and segmental designs are also
available.
 In practice, the orifice plate is installed in the pipe between two flanges. Acting as the
primary device, the orifice constricts the flow of liquid to produce a differential
pressure across the plate. Pressure taps on either side of the plate are used to detect the
difference. Major advantages of orifices are that they have no moving parts and their
cost does not increase significantly with pipe size.
 Conical and quadrant orifices are relatively new. The units were developed primarily
to measure liquids with low Reynolds numbers. Essentially constant flow coefficients
can be maintained at R values below 5000.
 Metering accuracy of all orifice flowmeters depends on the installation conditions, the
orifice area ratio, and the physical properties of the liquid being measured.
Venturi meters:
 Venturi meters have the advantage of being able to handle large flow volumes at low
pressure drops. A venturi tube is essentially a section of pipe with a tapered entrance

75. Flow meters
and a straight throat. As liquid passes through the throat, its velocity increases,
causing a pressure differential between the inlet and outlet regions.
 The flowmeters have no moving parts. They can be installed in large diameter pipes
using flanged, welded or threaded-end fittings. Four or more pressure taps are usually
installed with the unit to average the measured pressure. Venturi meters can be used
with most liquids, including those having high solids content.
Variable-area meters:
 Variable-area meters, often called rotameters, consist essentially of a tapered tube
and a float. Although classified as differential pressure units, they are, in reality,
constant differential pressure devices. Flanged-end fittings provide an easy means for
installing them in pipes. When there is no liquid flow, the float rests freely at the
bottom of the tube. As liquid enters the bottom of the tube, the float begins to
rise. The float is selected so as to have a density higher than that of the fluid and the
position of the float varies directly with the flow rate. Its exact position is at the point
where the differential pressure between the upper and lower surface balances the
weight of the float.
 Because the flow rate can be read directly on a scale mounted next to the tube, no
secondary flow-reading devices are necessary. However, if desired, automatic sensing
devices can be used to sense the float's level and transmit a flow signal.
Positive-Displacement Meters:
 Operation of these units consists of separating liquids into accurately measured
increments and moving them on. Each segment is counted by a connecting register.
Because every increment represents a discrete volume, positive-displacement units are
popular for automatic batching and accounting applications. Positive-displacement
meters are good candidates for measuring the flows of viscous liquids or for use
where a simple mechanical meter system is needed.
 Reciprocating piston meters are of the single and multiple-piston types. The specific
choice depends on the range of flow rates required in the particular application. Piston
meters can be used to handle a wide variety of liquids. Liquid never comes in contact
with gears or other parts that might clog or corrode.