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2014
Summer Internship Report
DESCON Limited
(June-July 2014)
Prepared By:
Muhammad Haider Ali Khan
SCME, NUST

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OVERVIEW
In the summer of 2014, I was offered an internship by DESCON Chemicals
limited. For a time period of 6 weeks I was employed as an interne at
DESCON OxyChem Limited, DESCON Chemicals Limited and DESCON
Headquarters Lahore. This report is a compilation of my learning and
experience working as an Internee at DESCON.
For the first 4 weeks I spent my time on Descon OxyChem Limited. A
state of art facility located just outside Lahore. The Plant produces
Hydrogen Peroxide under different brand names. It is a proud
presentation of DESCON Group as the facility produces more product
then it is designed for.
The second facility of DESCON Chemicals is their Chemical plant in the
same vicinity of DESCON OxyChem. This plant has a variety of products
and services for different industries. For textile manufactures, different
chemicals used for dyeing and finishing of textile products are provided
by DESCON. Similarly other customers of DESCON include the Paint
Industry which are buyers of a range of binders and additives of paint
dyes. Paper and Pulp Industries are also a client of DESCON which makes
different chemicals that enhance pulp performance. But the biggest
production of DESCON Chemicals are resin products which DESCON
Chemicals is the biggest producer in Pakistan.

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UNDERTAKING
I Muhammad Haider Ali Khan, undertake and guarantee that all that the
information and data used in making this report is taken and reproduced
with the Permission of DESCON Chemicals Limited. I also stress that all
the views expressed in the report are mine and mine alone they don’t
have any link with DESCON Chemicals Limited.
I certify that I take this Undertaking:
‘
Muhammad Haider Ali Khan
Student, SCME-NUST

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Table of Contents
 DESCON OxyChem:
1. Introduction Page 5
2. Hydrogen Plant Page 6
3. Peroxide Generation Page 12
4. Utilities Page 20
5. Concentration Unit Page 25
6. Filling Section & Jerry Can Production Page 26
7. Laboratory Page 26
 DESCON Chemicals Limited:
1. Introduction Page 27
2. Unit 2 Page 27
3. Unit 2 Utilities Page 30

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DESCON OxyChem Limited
Introduction:
DESCON OxyChem Limited is a part of the esteemed DESCON Chemicals Limited. It came into being in 2008 when a start-of-the art
facility was installed in the outskirts of Lahore with the help of the Swedish company Chematuer. The plant has an overall production
of 30,000 tons per year which fulfill demands of not only Pakistan as well as some of the International market as well.
The Oxychem Limited is composed of the following departments:
 Administration
 Marketing and Supply Management
 Production
 Maintenance
The main heart of this Company is the Production department which is tasked to run the facility. A group of operators, engineers,
managers and supporting staff work day and night 24/7 for 350 days every day with only plant shutdown for 15 days for the
purposes of maintenance.
Production Department is subdivided into:
 Hydrogen Production: Major Raw material for this process is Hydrogen.
 Peroxide Production: The Hydrogen produced is then converted to Peroxide.
 Concentration: Different Brands of peroxide are distinguished by concentration.
 Storage and Filling: Peroxide is packed & stored in accordance to International Standards.
 Jerry Can Production: Containers for Peroxide storage are produced onsite.
 Technical team: These are the pioneers of the production process.
 Utilities: Provides all other necessary support required during production. E.g. Steam, demineralized water etc.
 Laboratory: The lab ensures that the product and its production is up to International Standards.
The products of this plant are branded as follows:
 FOOROX 35: A food grade Peroxide of 35% Concentration
 ASEPTOX 35: Aseptic Grade Peroxide of 35% Concentration.
 DOLOX 35, 50 & 60: Technical Grade Peroxide of 35%, 50% and 60% Concentration respectively.
 TEXTOX 50: Technical Grade Peroxide for textile industry with 50% Concentration
 PRINTOX 50 & 60: Technical Grade Peroxide of 50% and 60% concentration respectively for pulp and paper industry.
These brands are used in applications like bleaching in the pulp and paper industry as well as in textile industries. It is
pharmaceutically used as an antiseptic for wounds. While it also is a major chemical used in detoxification and deodorization
techniques of environmental processes.
Hydrogen Peroxide is a very reactive and sensitive product which has to be stored in specially made containers depending on
requirement and shipment. The common forms of packing are:
 Jerry Cans made of High Density Poly Ethylene (HDPE) which can store 30 kg of Peroxide.
 Intermediate Bulk Containers (IBC) with a capacity of 1 ton.
 Containers and tankers with capacities ranging from 17-40 tons.

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Peroxide is a very unsafe chemical. Due to its highly oxidative nature it is highly reactive which is highly vigorous and dangerous. But
the biggest threat with Peroxide is that tough it is not flammable it is a combustion supporter. It is a temperature sensitive product
as the temperature rises peroxide decomposes into hydrogen and oxygen which are both flammable, hence if a flame or spark is
provided the fire triangle is complete resulting in catastrophic explosions. Hence peroxide is stored in special conditions and
additives like stabilizers are added to it to ensure minimum decomposition and reduce the sensitive nature of the peroxide.
Hydrogen Production:
Hydrogen is the main reactant required for the production of Hydrogen Peroxide. It is produced by the catalytic cracking
of Natural Gas specifically Methane with Steam. The following processes take place:
 Natural Gas Intake
 Natural Gas Desulphurization and Hydro treating
 Natural Gas and Steam mixing
 Catalytic Cracking in Furnace
 Process Steam Production through heat recovery.
 Hydrogen processing and impurities removal
The following main equipment are installed in the plant:
 Natural Gas Compressors
 Natural Gas Buffer
 Hydrotreating and Desulphurization of Natural Gas
 Natural Gas Preheater
 Catalytic Cracking of Natural Gas and Steam
 Process Boiler for Process Steam Production
 High Temperature Shift Convertor
 Pressure Swing Absorption to enhance Hydrogen Purity
 Hydrogen Storage
The following of the above mentioned equipment are reactors:
 Furnace: Catalytic Cracking of Natural Gas occurs with Steam inside the tube side of the furnace which has a
fixed bed of Nickel Catalyst.
 Hydrotreater and Desulphurization: These process take place in the same vessel. The top of the vessel is the
Hydrotreater section with a bed of Comax catalyst made of Cobalt Oxide, Molybdenum Oxide and Alumina.
While on the bottom of the vessel is the desulphurization section made of Zinc bed.
 High Temperature Shift Convertor: Which is filled with a fixed bed of Ferric Oxide and Chromium Oxide used to
convert Carbon Monoxide in Carbon Dioxide and as well as enhancing hydrogen purity.
Process Flow:
The following section covers the Process flow of the Hydrogen Plant:
 Battery Limit:
This section is where the Natural Gas comes into the system.

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The specifications of the Natural gas are:
Major Component:Methane (93%)
Temperature:15’C
Pressure: 2-3 Bar
Sulphur Content: Maximum 20 ppmv
Feed rate: 790-800 Kg/h
The flow is controlled with a gate valve. An orifice plate is connected to find the flowrate by means of differnetial pressure
calculator. Pressure and temperature transmitter keep recording and transmitting the pressure and temperature conditions
of the natural gas. The natural gas passes through a knockout drum which is made of different meshes, any condensate or
solid particles in the feed. The operating pressure of the Knockout Drum is 3 Bar if the pressure of the feed gas exceeds it a
Pressure Regulatory Valve activates venting of any excess pressure.
If the pressure is observed to be below 2 bar a booster compressor is switched on. Which a double stage single acting
positive displacement compressor. If the pressure is above 2 bar then the booster compressor can be bypassed straight into
the Natural Gas buffer.
 Natural Gas Buffer:
The Natural Gas after passing the battery limit is stored in a buffer at a pressure of 3 bar which is controlled by a PRV. Three
streams leave the buffer one of them goes to the utilities boiler, a second stream leaves into the burner section of the shell
side of the furnace and the third stream leads further into the hydrogen plant.
 Natural Gas Compressor Section:
The Natural Gas is compressed to a pressure of 22 Bar. The compressor used for this purpose are double stage single acting
compressors. They are two in number but at all times one of them is in action while the other is on standby. Heat
Exchangers use cooled demineralized water to cool the outlets of the compressor stage dischages, this is . Lube oil is
present in both the stages to make it frictionless and enhance compressor efficency by reducing energy losses.
The Pressure at each stage is:
Inlet Pressure: 2-3 Bar
First Stage Outlet: 7 Bar
Second Stage Oulet: 22 Bar
 Natural Gas Heater:
The Natural Gas is then heated to 400’c by means of the Syn Gas leaving the top of the Furnace. This essentail because the
working temperature of the Hydrotreater and Desulphurizer is 400’C
 Hydrotreater And Desulphurizer:
Two vessels are connected in series. In both Vessels, the top section is the hydrotreater and the bottom section is the
desulphurizer. Natural gas comes from the top and discharges from the bottom.
Hydrotreater Reactions:
The following reactions take place in the pressence of Comax Catalyst made of Cobalt oxide, molybdenum oxide and
Alumina:

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R can be any hydrocarbon chain or group. The main function of the hydrotreater is to convert the
unsaturatedhydrocarbon chains into saturated Hydrocarbon chains.
The Comax bed is a fixed catalyst bed with the bed size derived from the sapce velocity of 1500 cubic meter per hour per
cubic meter of catalyst.
Desulphurizer:
The hydrogen sulpide present in the feed is absorbed by means of zinc oxide bed. The traces of sulphur have to be removed
because sulphur is the catalyst posion for the Nickel catalyst used in the furnace’s tube section.
The optimum temperature for the dulsulphurizer is between 300-400’C to maintain a good conversion.
 Steam and Feed Mixing Point:
Before entering the Furnace the process steam generated from the process boiler is mixed with the Natural Gas. The ratio
of Steam to Gas should be 3:1 at all times to ensure proper cracking of the natural gas. If the ratio is disturbed coke can get
deposited on the Nickel Catalyst in the Furnace tubes thus effecting its efficency.
The Calculation of this 3:1 ratio is as follows:
Natural Gas = 600 m3
/h
Steam = 1640 kg/h
Now moles of H2O in steam= 1640 (kg/h) / 18(kg / moles) = 91.1 moles/h
Similarly lets assume for a flow of 600 m3
/h of Natural Gas for the given composition contains 365 kg/h of Carbon or 30.4
atoms/h of Carbon. So:
Ratio = 91.1/30.4 = 3 or C/Steam = 3:1
A flow controller is adjusted on both Natural Gas and Steam lines to maintain this ratio at all times.
The Process steam is generated form the the Process Boiler it enters the mixing point at 29 Bar Pressure while the Natural
Gas comes at 21 Bar Pressure. The loop after this mixing point is designed of such length so that proper mixing of the steam
and natural gas occurs and decrease the pressure before it enters the furnace tube side.
 Feed Preheater:
The mixture of steam and natural gas has to be preheated to 510’C before it enters the Furnace to enhance its efficency.
The flue gases generated from the combustion in the shell side are at a discharge temperature of 950’C they are used in the
process superheater as heating agent.
 Furnace:
The primary function of the furnace is to provide heat to the highly endothermic reforming reactions occurin gin the tube
section of the furnace. While the furnace is specially designed for the best kind of heat recovery where all the waste heat
produced utilized in the pre heating of feed and formation of process stream.

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Like all furnaces this furnace has two sections:
1. Radiant Section: This section consists of the 14 catalyst filled reformer tubes which are conncected to the process
boiler to utilize the excess heat content of the syn gases by boiling water into steam.
2. Convective Section: This includes the shell side of the furnacewhich is connected to the the feed preheater and the
air preheater The hot flue gases have a high amount of heat content which is used for preheating before the gases
are vented out at much cooler temperature.
The Furnace used is called a Balanced Draught Furnace. The Shell side is connected to a air circulation curcuit which is
equipped with a forced draught and an induced draught fan. While there are 14 tubes in which there are fixed bed of
Nickels catalyst. The steam and natural gas mixture enters from the bottom of the tube at a temperature of 510’C and
leaves the top of the furnace as Syn Gas at the temperature of 800’C
While on the shell side of the furnace Natural Gas combined with the Off Gases Coming from the PSA are used as fuel and
air is forced into the shell by means of a forced draught fan and sucked out of the top by an induced draught produced by
an induced draught fan. The shell of the furnace has to be under vaccum at all times so that there is no build up of gases in
the shell that can cause increase in pressure in the system which can lead to unsafe conditions. The temperature of the flue
gases is about 800-900’C and it is used to heat the air and feed in their respective preheaters. This minimizes use of extra
energy as all the energy required to heat is generated through heat recovery.
In case if the temperature of the furnace of the furnace oultet is very high it can damage the preheat heat exchangers thus
a recirculation loop is present which recirculates the cooled flue gases after heat exchange in the furnace loop to bring
down the temperature.
Ceramic are used as a refactory material in both the convective and radiant section of the Furnace to withstand
temperatures as high as 900’C.
The Reforming reactions are as follows:
Desired Reactions:
Undesired Reactions:
In case if the C/H2O ratio falls below 3:1 the following undesired reaction take place:
This reaction result in Coke Formation which deposits on the Nickel Catalyst surface.This retards the catalyst activity. In case
of coking steam is used to regenerate the catalyst surface. The usual life of catalyst bed is 3-4 years.
Burner:
The most important and the most dangerous component of the furnace is the burner.It is specifically designed to operate
using the low pressure and low calorific value off gases with a make up of natural gas.
The operation of the burner and furnace is interlocked with the following equipment to ensure that the operation is in safe
operation:

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1. Fuel Gas Combination Pressure: If the Fuel Gas pressure falls below a set value the furnace cuts off or trips.
2. Steam Drum Level: The optimum level of the steam drum is 50% but if it falls below 30% the furnace cuts off
because the syn gas coming at very high temperature can damage the process boiler tube.
3. Induced and Forced Draught Fan: If any of these two fans malfunction the balanced draught in the furnace gets
disturbed resulting in unsafe conditions.
4. Steam and Carbon Ratio: If the ratio is disturbed it results on improper reforming of natural gas or coking both are
dangerous. Coking effects the catalyst activity while improper reforming will affect the Hydrogen production and
purity.
 Process Boilers:
The Syn Gas leaves the top of the furnace at 800-850’C. This is a very high temperature and can damage the equipment,
hence this temperature is reduced by generation of steam in the process boiler.
The process boiler is basically a heat exchanger and equipped with a steam drum. The steam dream is basically filled with
demineralized and deairated water which is at 200’C and at 29 Bar coming from the deairator.
The Syn Gas passes through the heat exchanger tubes while the water from the steam drum enters Boiler shell and is
converted into steam at 400’C and 29 Bar Pressure. A thermo syphon is created by which colder water flows into the boiler
and hotter steam flows into the steam drum from where it is exported and used in the furnace.
 High Temperature Shift Convertor:
Syn Gas reaches the HTSC at a lowered temperature of 400’C. The basic purpose of HTSC is to remove out the Carbon
Monoxide traces in the Syn Gas which decreases the toxic nature of the Syn Gas as Carbon Monoxide is very toxic as well as
furnace efficiency which is further effected through shift conversion.
HTSC is a reactor with a catalyst bed made of Ferric Oxide and Alumina Oxide. The following reaction takes place:
 Syn Gas Heat Recovery:
Syn Gas temperature before it reaches the PSA should be at 40’C while after HTSC the Natural Gas temperature is 400’C
plus so it is cooled by means of heat recovery. Syn Gas is cooled by the following heat exchanges:
Deaerator:
The water used in the Steam drum is demineralized and deaerated. Demin water from the Demin plant is taken pumped by
means of multi stage centrifugal pumps with a discharge pressure pf 29 Bar into the Deaerator. Here it is deaerated by
means of air which blows out any Carbon dioxide in the water which can dissolve to form carbonic acid which is corrosive in
nature plus it is dosed with further chemicals like Sodium hydroxide (pH Control) and Phosphate (Hardness Treatment). Syn
Gas heats up the water here to 200’C
Deaerator Make Up:
The deaerator make up water is also preheated in advance by means of heat exchangers and syn gas.

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 Pressure Swing Absorption
The cooling of Syn gas can result in condensate formation which are removed by means of a knockout vessel. After that Syn
Gas enters the PSA vessels. There are 4 PSA vessels all are active but different processes are taking place in all the vessel at
the same time.
PSA is filled of 4 absorbent layers bottom layer is aluminia used to absorb H2O vapors, middle layer is activated carbon used
to absorb CO2 and methane while the uppermost layers are made off a mixture of metals which absorb nitrogen and carbon
monoxide.
These gases get trapped in the absorbent voids after a certain time the vessel reaches full capacity and pressure after which
syn gas depressurizes and moves into the next vessesl. H2 gas is recycled and purged back into the vessel to release the
trapped gases and send them to the off gas tank. After regeneration the PSA vessel is repressurized.
After passing PSA the hydrogen purity boosts from 71-74% after furnace to 99.99% after PSA. PSA is necessary because
Carbon is a catalyst poison in Peroxide production.
 Off Gas Vessel:
Off Gases absorbed in the absorbent pores in the PSAs are purged out of the pores by a pure hydrogen purge stream. They
are collected in the Off Gas Vessel, the components collected in the vessel are majorly Carbon Oxides, Water Vapors,
Unburnt Methane and Hydrogen gas. These gases are used in the Shell side of the furnace with the mixture of Natural Gas
as a fuel. Though these gases have 3 times less calorific value as compared to Natural Gas they are potentially hazardous if
vented out in the atmosphere hence they are recycled to decrease Natural Gas use as well as utilizing there heat energy.
 Hydrogen Buffer:
The Pure Hydrogen Feed of 99.99% Concentration is then stored in the hydrogen buffer under a pressure of 16 Bar. From
the buffer it is exported to the Peroxide Plant for use in the hydrogenator.
Essential Control Loops:
The following control loops are essential in the Hydrogen Production:
 Flow Loop:
Flow loop are designed to control the flowrate of a flow stream at a defined value. The following flow loops are
installed:
1. Steam and Natural Gas Mixing Point: The flowrates of the steam and natural gas are controlled by their
respective flow controllers with the aim to maintain the ratio of steam/C ratio at 3:1 because any
deviation from this can cause coking on the Nickel Catalyst Surface.
2. Burner: In the burner the flowrate of the offgas has to be higher than natural gas. Because if the
flowrate of Natural Gas is higher it has three times more calorific value then off gas so it will result in
sudden uncontrolled increase in temperature resulting in dangerous conditions.
 Temperature Control Loop:

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The temperature control is usually installed on a heat exchanger it manipulates the flow of the cooling and
heating element such that a specific temperature is maintained. The following temperature control loops are
installed:
1. Syn Gas Outlet at Boiler:- The temperature at the outlet of the Boiler should be above 400’C so that the
Hydrotreater and Desulphurizer are at their optimum working conditions:
2. Feed Preheater Outlet: At the outlet of the preheater the temperature should be at 510’C to increase
the efficiency of the furnace.
3. Flue Gas Temperature: The Flue gas temperature should not be very high because it can the damage the
process superheater and air preheater thus if the temperature rises very high the air recirculation loop is
activated so that the cooled flue gases are recirculated to cool the equipment.
 Level Control:
The level controller is installed to maintain the level in a system by manipulating the inlet or discharge flowrate
in a system. The following level control loops are designed and installed:
1. Steam Drum: The level of water in the steam drum has to be maintained at 50%-30% below 30% level
means the process boiler is not fully filled resulting in damage of boiler by the high temperature Syn
gases.
2. Deaerator: The level of water in the deaerator has to be maintained at a certain level. If the level of
water is very low air will carry over the demin water and if the level is very high air will not be able to
pass through it.
 Analyzer:
Analyzer is designed to analyze the compositon of any element of a stream. The analyzer is installed on the
steam and carbon mixing point to make sure the ratio of steam to carbon is 3:1
Hydrogen Peroxide Production:
Hydrogen Peroxide is basically produced by the cyclic reduction and oxidation of Alkyl Anthraquinone in this case Ethyl
Anthraquinone. The following Steps are essential in the production of peroxide:
1. Production of Working Solution
2. Hydrogenation of Working Solution
3. Oxidation of Working Solution
4. Regeneration of Working Solution
5. Extraction of Peroxide
6. Working Solution Dryer
7. Peroxide Concentrator
The Peroxide crude can be extracted into different compositions like 35%, 50% and 60% depending on their uses and
demands.
Ethyl Anthraquinone is a powder which has to be converted to a Working Solution which can be converted into a flowing
solution that can be pumped from equipment to equipment. The Working Solution is made of the following
components:

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 Solvaso: Salvaso is an aromatic organic solvent which can dissolve Ethyl AnthraQuinone.
 Tetra Butyl Urea (TBU): Used to dissolve TetraHydroEthylAnthrahydroQuinone.
 Tri Octyl Phosphate (TOP): Corrison Inhibator and Stabilizer.
Process Flow:
The following is the process flow description of the production of Hydrogen Peroxide:
 Hydrogenator Section:
The basic purpose of the hydrogenator is to convert the Ethyl AnthraQuinone into
TetraHydroEthylAnthrahydroQuinone which is further oxidated to give Peroxide.
The Working Solution is taken from the W.S Buffer and passed through a tank where it is mixed with the Pladium
Catayst then it passes through an educator into the hydrogenator through spray noozles at the bottom of the
reactor vessel. A recycle stream coming from the primary filters mixes with fresh stream of W.S in the educator.
The Hydrogenated W.S is collected from the top of the reactor vessel and passed into the primary filters. After
passing through the primary filter the W.S is stored in the Oxidiser Buffer tank.
While the hydrogen stream comes from the hydrogen point. Its flow is controlled by a PRV and FCV. The
hydrogen is injected into the reactor vessel from the bottom. Whereas the excess hydrogen leaving the top of
the hydrogenator is taken into the hydrogen recycle compressor and passed into the seal tank. This hydrogen
stream is continuously recycled and scrubbed to remove any entrained W.S. Some of it is bled into a condenser
which further condenses the W.S vapors entrained before being vented after passing through a demister. All the
W.S retrieved is collected in the seal tank after which it is recycled as W.S into the Water/W.S separator tank
before ending up in the W.S Make Up tank. While the rest of the hydrogen is recycled mixed with the makeup
stream before entering reactor.
Primary Filter:
The filter is of candle type. It is made of porous candles that are 81 in number. The Primary filter section is
composed of 5 filters: 3 of them are in action, 1 is on standby/Cleaning and the left one of them is on backwash.
The 4 working filters periodically put on back wash.
The W.S comes into the shell side of the Primary Filter from the bottom while most of the fluidized and carried
over catalyst falls back into the reactor most of it flows with the W.S. The catalyst being of greater size then the
pores of candle is retained in the shell while W.S flows into the candles and moves on to the oxidizer buffer tank.
During back wash, W.S from the oxidizer feed tank is pumped into the candles of the filter it flows into the shell
of the filter and carrying the catalyst stuck into the educator where it is mixed with fresh W.S stream before
being injected into the reactor.
Chemistry of Process:
The following reaction take place in the hydrogenator:
1. EAQ Reduction:

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2. Tetra Reduction:
3. EAQ-Tetra Equilibrium:
4. Tetra Formation:
Process Variables:
Inlet Temperature: 44’C Operating Pressure: 0.8-1.2 kg/cm2
Outlet Temperature: 52-59’C
Control Loops:
The following control loops are present on the hydrogenator section:-
 Pressure Controller:
Pressure Controller at Hydrogen Inlet: The hydrogen stream comes at 16 bar which has to be controlled
to the operating pressure of 0.8 to 1.2 kg/cm2
 Level Controller:
a) Seal Tank: The level has to be maintained in the tank to ensure Hydrogen stream doesn’t carry over
W.S with it.
b) Hydrogenator: The level in the hydrogenator has to be maintained to enhance the reactor efficiency.
 Temperature Controller:
Preheater: W.S has to be heated to 44’C and its temperature has to be maintained at this temperature
for efficient working of Hydrogenator Reactor.

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 Flow Controller:
The flow inlet of W.S in Hydrogenator Reactor: The W.S has to be controlled such that the residence
time of W.S is enough for proper hydrogenation.
Safety:
Hydrogen has a wide explosive range with Oxygen. Thus Oxygen has to be monitored. If the limit of Oxygen in
the system rises the hydrogenator is purged with Nitrogen and system is isolated. The system also has an
inherent safety against oxygen entering the system which is consumed by oxidation of
tetrahydroanthrahydroquinone (H4EAQH2) converting it into peroxide (H2O2) and TetraHydroEAQ (H4EAQ)
 Oxidiser Section:
The oxidizer section starts from the oxidizer feed tank. The W.S is pumped from the feed tank into the
secondary and safety filter to remove any catalyst particles that might have passed through into the oxidizer
section. A catalyst detector is installed as additional safety element.
The working solution is cooled by means of heat exchange with cooling water before it is showered from the top
of the oxidizer reactor. The reactor vessel is made of 8 sieve plates. While oxygen is taken by means of Air. Air is
compressed by means of air compressor and stored in the process air buffer. From where it enters the oxidizer
reactor from the bottom. A counter current reaction takes place where W.S comes from the top and is
converted into peroxide and W.S collected from the bottom. The W.S and Peroxide is cooled then stored in the
extractor feed tank.
Whereas the gases are collected on the top of the oxidizer. They are then cooled so that any of the entrained
W.S is condensed. The W.S condensate is then sent into the degasser. Here the W.S is degassed and the gases
sent into the solvent recovery unit to retrieve any further W.S left before venting the gases out. While the W.S
condensate flows into the extractor feed tank.
Chemistry of the Process:
The following reactions take place in the oxidizer:
1. Oxidation of TetraHydroEthylAnthraHydroQuinone:
2. Anthra Oxidation:

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Safety:
The safety requirement of the oxidation section is that no trace of Pladium catalyst enter the oxidizer as
this catalyst is supporter of the decomposition of the peroxide product. Which can decomposes in the
presence of the catalyst into Hydrogen and Oxidation which are both supporter of explosive
combustion.
Process Parameters:
Oxidizer Inlet: 37-42’C Air Inlet Temperature: 40’C
Oxidizer Outlet: 52-60’C Pressure: 1.5-1.8 atm
Control Loops:
The following control loops are installed on:
 Level Control:
a) Level of Oxidizer: The oxidizer level has to maintain so that the proper retention of reactants
occur in the oxidizer to give required contact time.
b) Level on top plate of oxidizer: The level on the top plate is 50%. If the level is less process
becomes less efficient whereas if its high the carry over amount increases.
 Flow Contol:
a) Flow control to secondary filter.
b) Flow control on W.S inlet to Oxidizer: It should be adjusted to maintain retention time.
 Temperature Control:
a) Backwash Cooler: The backwash comes from the oxidizer feed tank at 52-59’C and is cooled to
44’C the operating condition of the oxidizer because it has to enter the oxidizer again.
b) W.S inlet: The W.S has to be between 37-42’C whereas it comes from feed tank at 52-59’C.
 Pressure Control:
Pressure has to be maintained within the reactor between 1.5 to 1.8 bar.
 Extractor:
The W.S is pumped into the bottom of the extractor. The extractor is composed of 32 sieve plates. The
Demineralized water is showered from the top. The W.S is a lighter phase while the peroxide phase is denser
and heavier so it settles down at the bottom.
At the top of the extractor a demister pad is installed whereas the basic purpose of it is to reduce the overhead
aqueous content.
Whereas the Peroxide crude is collected from the bottom of the extractor and prepared for storage.
Dilute Phosphoric Acid is used as a stabilizer in the extractor. To control the decomposition of Hydrogen
Peroxide.

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Control Loop:
 Flow Control:
a) W.S Inlet
b) Demin Water
c) Crude outlet
 Level Control:
Level in the extractor has to be maintained so that proper extraction of the fluids occurs.
 Temperature Control:
The crude is cooled because peroxide is temperature sensitive as it decomposes with temperature. So
the temperature is controlled by means of cooler.
Crude Purification:
The crude Hydrogen Peroxide is cooled after leaving the bottom of the extractor. After extraction the crude contains
some amount of demineralized water and the W.S which has to be removed as these make the peroxide product
impure. These impurities are removed by the process of coalescing by means of coalescers
Coalescer:
A coalescer is a device used to perform coalescence. Coalescence is a phenomenon in which an emulsion is separated
into its different components.
They are two basic types of Coalescers installed on the plant:
1. Hydrophilic: Those that attract water molecules
2. Hydrophobic: Those that repeal water molecules
The coalescers used are of mechanical assembly in which baffles and filters are used to coalesce the particles.
The crude mixture passes through coalescer and is separated into Hydrogen Peroxide and a mixture of W.S and
entrained water. The recovered W.S is sent into the oxidizer degasser while the removed demin water is sent to the
demin storage tank and recycled in extractor.
The separated hydrogen peroxide flows into the holdup tanks from where it is sent to the concentration unit.
Safety:
Phosphoric acid is added into the holding tanks to stabilize the Hydrogen Peroxide which decomposes with increase in
temperature. Incase temperature rises suddenly Nitrogen is purged into the tank so that the oxygen and hydrogen do
not react to cause an explosion.
Process Conditions:
Temperature: 40’C Concentration: 35% Pressure: 1 atm

18. Page | 18
Working Solution Drier:
The W.S from the top of the extractor is collected and heated in the W.S heater by means of steam. It is then sent to the
Drier. The drier consists of sieve plates; the W.S is showered from the top while dry air is blown from the bottom. The
Air takes away the water content and is sent to the solvent recovery unit to remove any entrained W.S before being
vented out. The W.S is then cooled by means of cooling water before being passed through a vacuum pump where the
pressure is reduced to flash out any excess moisture. This excess moisture is sent to the drain separator.
Process Parameters:
Temperature in Drier: 50-55’C
Process Controller:
Pressure Control on Vacuum Pump: The pressure in the vacuum pump has to be below atmospheric pressure at all times
so that the vapors can be flashed out.
Solvent Recovery:
Off Gas W.S Recovery:
All the air vents enter this unit. The important vents are as follows:
1. Oxidizer Off Gas Demister
2. Oxidizer Degasser
3. Drier Off Gas
Three vessels are installed for solvent recovery. In the vessel there are absorbent materials that trap the carried over
W.S while the gases are vented out. At all times two of the vessels are in operation while one is in regeneration. During
regeneration steam is entered from the top of the vessel and it forces out the W.S. The W.S falls into the condenser
where it is condensed. After Condensation it is sent to drain treatment.
Drain treatment:
All the liquid drains lead into the drain tank. After which it is sent to the separator. In the separator the W.S and water
are separated from one another on the basis of density. W.S is the lighter phase so it floats on the top of the separator
whereas the water settles down at the bottom. The W.S is collected from the top and sent to the make up tank while
the recovered water is discharged.
Importance of Solvent Recovery:
The W.S is made of very costly chemicals and solvents so any wastage of the solution can result in throw away of a
recoverable investment. Hence a special solvent recovery system is designed so that there is negligible discharge of W.S
either in vapor or liquid form. Despite employing solvent recovery the plant loses 1 kg of W.S per day of production.
Solution Regeneration:
Due to the continuous recirculation of W.S in the system, the active quinones get converted to undesired unactive
quinones by means of side reactions. These undesired quinones have to be regenerated.
For the regeneration purposes about 7% of the main W.S stream is taken from the oxidizer feed tank by means of a
pump and sent to the economizer where it is preheated by the hot stream leaving the regenerator. It is then feed to the
regeneration column that is filled with alumina. After regeneration the stream is used as heating agent in economizer

19. Page | 19
before it is sent into filter to remove entrained alumina catalyst. The regenerated steam is sent to the hydrogenator
feed tank.
Undesired Reactions:
 Hydrogenator:
Side reactions in hydrogenator are as follows:
1. Over Hydrogenation:
2. Anthrone formation:
 Oxidizer:
Side reactions in oxidizer are as follows:
1. Epoxide formation
Regeneration Reactions:
The following regeneration reactions take place:
1. Epoxide Recovery
2. Recovery of TEAQs:

20. Page | 20
3. Recovery of Oxanthrone:
W.S Make up Tank:
The W.S make up is used to compensate for any loss of W.S or active quinones that have been converted into non
recoverable products.
The following streams enter:-
1. W.S from the Seal tank is sent to the separator before being pumped into the make up tank.
2. W.S solution from solvent recovery enters into the separator before being sent to the W.S make up tank.
3. W.S solutions from drain end up in the separator before being sent to make up tank.
The W.S make up tank is equipped with an agitator and steam pipe jacket.
The chemicals added are:
1. Solvaso: An aromatic organic solvent for EAQ
2. Tri Butyl Urea: Solvent for TEAQs
3. Tri Octyl Phosphate: Corrosion inhibitor
Utilities Section:
Utilities section includes:
1. Raw Water
2. Demin Plant
3. Cooling Water
4. Chilled Water
5. Boiler
6. Instrument Air and Nitrogen Production
 Raw Water:

21. Page | 21
Water from the underground water table is pumped by means of a pump into the raw water tank. The tank has a
capacity of 1700 ton. The main uses of raw water are:
1. Chilled Water Production
2. Cooling Water Production
3. Demineralized Water Production
 Demin Plant:
Water consumed from the surface contains a heavy number of Totally Dissolved Solids if used in equipment can
cause scaling. Scaling is harmful becomes it can decrease heat and mass transfer as well choking in equipment. Thus
raw water has to be demineralized before using. The basic process mechanism is ion exchange through resins.
Special designed resins are installed in the demin plant with abilites to remove cationic and anionic salts.
Three types of Resin Beds are available:
1. Cationic Bed
2. Anionic Bed
3. Mixed Bed
Cationic Bed:
Cationic bed is mainly made of Styrene DivinylBenzene Copolymer matrix with the functional group of Sulfonic Acid.
The structure is given below:
The R functional Group is attached to an H negative ion. Any salt in the water exchanges its cation (Positively
Charged Ion) with the Hydrogen from the resin giving acids.
The properties of water after passing the cationic region are:
pH= 3-4
Conductivity= 1200-1300 micro Siemens
The reactions occurring in the cationic bed region are:

22. Page | 22
The vessels and pipes are equipped with a rubber and Poly Vinyl Chloride lining to stop the acids from corroding the
vessel surface.
Anionic Bed:
Anionic Resin Bed is made of the same matrix as that of cationic resin i.e. styrene divinyl benzene copolymer but a
different functional group. The functional group is hydroxyl group (-OH) so that the resin structure is (R-OH).
The main function of anionic bed is to remove the anions (negatively charged) of the acids produced by cationic
exchange. The following Reactions take place:
The properties of water after anionic section are:
pH= 7-8
Conductivity: 50-80 micro siemens
Degasifier:
Degasifier is a vessel designed to remove gases through a liquid stream. In demin plant the degasser is used to
remove carbon dioxide which dissolves in water to form carbonic acid which later on can cause corrosion in the
equipment and pipes.

23. Page | 23
In degasfier, water is showered from the top of the vessel. It falls on sieve plates while air is blown from the bottom
of the vessel by means of forced draught fans.
Carbonic acid is unstable. Under the stress of the air flow it decomposes as follows:
The degasifier is installed at the outlet of the catonic resins before water enters the anionic section.
Mixed Bed:
Mixed bed is a combination of both anionic and cationic resins. The top layer is made of Anionic resin and the
bottom layer of Cationic resin which are used to further polish the water.
After passing the mixed bed the water is stated to be demineralized with the following properties:
pH = 7
Conductivity= 0.1 micro Siemens
Regeneration:
After sometime the cationic and anionic resins are consumed so they have to be regenerated again. The operation
and regeneration times of the resins are:
Anionic and Cationic Resins: Operation time is Eight Hours and Regeneration time is Four Hours.
Mixed Resins Bed: Operation time is Two Weeks and Regeneration time is Four Hours.
Regeneration Chemicals:
The chemicals used in regeneration are:
Anionic Section:
Hydrochloric acid is used. The Reaction is as follows:
Cationic Section:
Sodium Hydroxide is used. The Reaction is as follows:

24. Page | 24
Regeneration Steps:
There are four steps in the regeneration process. They are as follows:
 Backwash:
In this step demineralized water is used as backwash. So that any stuck salts are removed.
 Caustic/Hydrochloric Acid Injection:
In this step the respective regeneration chemicals are dosed into the anionic and cationic resins in this step.
 Slow Rinsing and Fast Rinsing of Water.
 Chilled Water:
Chilled Water is produced by means of the refrigeration cycle of Freon. It is the property of Freon gas that on
compression it liquefies and cools down.
Freon gas is compressed and sent to the condenser after which it is expanded by means of an expansion valve which
completely converts the Freon into a chilled liquid. This liquid then passes through the evaporator where warm
water enters the shell side and Freon in the tubes. There is heat transfer the water cools down while Freon heats up
and converts to gas which is then compressed and the cycle is repeated.
 Instrument Air and Nitrogen Production:
Air is compressed by means of screw type compressor into the drier section. The drier section there are vessels in which
there are absorbing materials. These absorbing materials absorb any oil and water vapors that might have been included
in the water are absorbed. The regeneration cycle of the vessels is required at 24 hours after which the vapors and oils
absorbed are vented out. It’s the characteristic of instrument air is that its oil and water vapor free. It is then sent to the
buffer from where it is used in running the equipment.
From the Air buffer some of the Gas is then sent to the Nitrogen plant where there are Pressure Swing Absorbers. The
absorber material include:
1. Activated Carbon
2. Coconut Shell
3. Alumina Balls
The major resource of Nitrogen is air which contains 79% nitrogen and 21% impurities or undesired gases. These gases
are absorbed by the absorbents while nitrogen passes through to the Nitrogen Buffer. The percentage of oxygen in the
nitrogen should be below then 1% because Nitrogen is mostly used to create an inert environment in the vessels if
oxygen is present in considerable amount it can react with the constituents of the vessel. An analyzer is installed to keep
a check on oxygen amount, if the amount is considerable the flow rate of process air into PSA vessels is reduced to
increase retention time in the vessels. But if it’s very large that is an indication of absorbent failure.
 Boiler:
The utility boiler is a fire tube boiler. Natural gas is used as fuel in the tube which ignites to give a flame. The flame is
used to boil demineralized water to give steam.

25. Page | 25
The capacity of the boiler is 5.5 ton production per hour but the amount of steam produced is around 4 ton/ hour
where the rest of the steam requirement is fulfilled by the process boiler in the hydrogen plant. The boiler runs 24
hours per day for the whole year.
Chemical agents are dosed in the boiler after some time to control the following problems:
1. Corrosivity controlled by pH reduction
2. Foaming is controlled by TDS removal
3. Scaling is caused by TDS so water hardness has to be controlled
 Cooling Tower:
The cooling tower utilized are of induced draught counter flow type.
Tower Properties are:
 Capacity: 1800 cubic meter per hour
 Number of Cells: 3
 Inlet Temperature of Hot Water: 40-45’C
 Outlet Temperature of Cold Water: 32’C
 Relative Humidity: 80%
Cooling water is treated for:
 Scaling: Sulphuric Acid is dosed to reduce pH and TDSs
 Corrosion Inhibitors: Chromate, phosphate , silicates etc. are removed
 Bio Treatment: Biocides and germicides are added to control bio growth of microorganisms.
Concentration Unit:
The peroxide crude after extraction is about 35% by weight solution. DESCON brands demand concentration of 50% and
60% as well. These concentrations are achieved by the process of crude concentration.
For concentrating crude from the holding tanks are sent to the concentration unit which is consistent of:
 Falling Film Evaporator:
In the falling film evaporator crude is showered from the top of the evaporator. Whereas Steam is flown from the
bottom of the evaporator. A counter current simultaneous mass and heat transfer process occurs in which water
vapors are evaporated and carried over with steam into the distillation column.
Whereas the concentrated peroxide is collected from the bottom and stored in the storage tanks.
 Distillation Column:

26. Page | 26
The vapors of steam coming from the evaporator entrain some of the peroxide with It. In the distillation column
there are sieve plates. Steam is provided in the distillation column jacket as a heating agent. The water vapors are
stripped out while the entrained Peroxide falls down as bottom product and is sent into storage. Whereas the water
vapors at the top of the column are condensed and refluxed to enhance purity of product.
Jerry Can Production and Filling Area:
Peroxide is packed and transported in the following methods:
1. 30 kg Jerry Cans
2. Intermediate Bulk Containers
3. Tankers of different tonnage.
Jerry cans and IBCs are produced locally in the Jerry can production area.
Whereas the filling of peroxide is done in the filling area where Filling machines fill the jerry cans and IBCs.
The Working solution is pumped from the storage tanks into an intermediate tank from where they flow into the filling
machines by means of gravity.
For tankers their containers are checked for any kind of leakages before they are filled and weighed before being
dispatched to the clients.
Additives and stabilizers are added to save the peroxide from decomposition due to temperature.
Laboratory:
The laboratory is tasked with the job of ensuring that the product is up to standards and the production process is not
harmful to the environment. Regular samples are taken and analyzed to see if the product is off the desired
specifications. The Lab also analyzes the Raw Water, Cooling Water and Demineralized Water to measure its TDS
because they can cause scaling which damages the equipment.

27. Page | 27
DESCON Chemicals Limited
Introduction:
DESCON Chemicals are amongst the biggest conglomerates manufactures of Pakistan since three decades. In 1977, DESCON was
founded now the brand comprises of Descon Chemicals Limited, NIMIR Resins Limited, Descon Corporation Limited and Descon
Oxychem Limited. The company provides facilities of manufacturing, packing and trading of a variety of chemicals under the same
roof.
Based in Lahore the Company has a workforce of 600 workers that work day and night to manufacture around 200 innovative
products for markets.
The vision and aim of the company is to build and maintain the Brand Equity not only in Pakistan but on a global scale. This vision is
currently being materialized in the form of DESCON Oxychem Limited which not only serves the need of the domestic market but
also provides product for markets in Turkey, India, Sri Lanka, Bangladesh, South Africa and UAE.
The products offered by DESCON Chemicals Limited are categorized in the following Business Lines which cater to specific sectors of
the market:
 Textile Auxiliaries
 Polyester Resins
 Coating and Emulsions
 Pulp and Paper Chemicals
 Adhesives and Graphics
 Trading and Exports
The basic manufacturing process is a batch type of process. Products are made by a fixed number of steps and a predefined recipe.
The facility is divided into 4 major units:
 Unit 1: This facility makes Resins for the paint and textile industry
 Unit 2: This facility makes product for the textile and paper industry
 Unit 3: This facility provides services for the paper and pulp industry
 Unit 4: This facility manufactures polymers
Unit 2:
Unit 2 is facility designed to make products for the textile and paper industry. The biggest product of the facility is
Optical Brightener and Softener for textiles and paper pulp. The production is batch in nature so for all the products
there is a predefined recipe which has to be followed to make the product. The important chemicals used are:
1. Sodium Carbonate
2. Ice
3. Nitric Acid
4. Melamine
5. Raw Water
6. Cyanic Chloride
7. Urea
8. Caustic Soda

28. Page | 28
The basic equipment are:
 Reaction Kettle Vessels
 Solid Mixers
 Additive Mixers
 Nano Membrane Filter
 Soft Water Production and Storage
 Cooling Tower
 Ice Unit
 Tray drier
 Flaker
 Grinder
 Membrane filter press
The main Product form is off the following type:
 Solid type: In form of Powder and Flakes depending on the recipe and requirement
 Liquid type
Equipment:
The equipment installed in the plant is described as below:
 Reaction Kettle Vessels:
The Vessel is a kettle equipped with a condenser and an agitator. The inner side of the kettle has cooling pipes
while the outer side of the kettle is heating pipes. The chemicals are added inside the kettle from the mouth of
the kettle in amount and order defined by the recipe. Heating and cooling is done by the means of heating oil
and cooling water respectively. The agitator is used as a mixer and its speed can be controlled depending on the
amount of mixing required. During reaction fumes can be formed which enter the condenser where they are
condensed into liquid by means of cooling water and fall back into the kettle. There are 4 kettles attached in the
facility with capacity ranging from 2-12 tons. A suction circuit is attached so that in case if a product is to be
loaded into the kettle it can be sucked in from the bottom. Whereas a vacuum circuit is present so that the
product can be discharged from the bottom of the kettle into the storage containers. A line carries the premix
from the premix mixer tank into the kettle. A nitrogen cylinder is attached to the kettle for nitrogen blanketing.
Sometimes a batch has to be held up to give proper retention or shortage of workforce to fill it, in such case
nitrogen is blanketed on the solution surface to safeguard it from the excess gases in the system which can react
with the solution causing it to contaminate.
 Premix Mixer Tank:
A premix tank is added to each of the kettle vessels. Sometimes it’s the requirement of the recipe that a premix
of reactants is added to the kettle in a form of a mixture. These tanks are basically mixers, the chemicals are
added in accordance to requirement and mixed by means of agitators before being fed into the kettle.

29. Page | 29
 Nano Filter:
A product made at this facility is named Nano liquid. It is a suspension of solids of nano size in an organic
mixture. After production this liquid contains a lot of water content which is a major impurity. These impurities
are removed by means of a membrane filters. The filter is composed of three membranes in series. The pore size
of the membrane is in nano size. The water particles have smaller then nano size so by means of reverse osmosis
they pass through the membrane and are discharged while the nano liquid flows into the storage tank. The
storage tank is equipped with a scrubber which continuously scrubs out the left out impurities and water vapor
before it is packed into the storage containers.
 Membrane Filter Press:
Sometimes the product requirement is in form of cake or powder. For such product the solution from the kettle
is loaded into the membrane press. The solution is feed into the membranes which are pressed against each
other. The liquid passes through the membranes under pressure while the solid is retained in the form of cake
on the cake surface. The cake is scrapped of while the effluent liquid is discharged.
 Tray Drier:
The cake removed from the membrane filter press is loaded into the trays of the cake drier. The drier has tubes
containing heated oil coming from the furnace. Air is taken from the bottom heated by means of the heating oil.
The heated air rises up through the sieves in the tray and evaporating the moisture content in the cake. The air
gets discharged to the atmosphere.
 Grinder:
After drying the cake is grinded into powder by means of a gyratory jaw crusher. This powder is then sent to the
mixing and packing section.
 Mixer:
The grinded cake powder is then fed into the centrifugal mixer. In this mixer the grinded powder is rotated at
different RPMs depending on the extent of mixing required. The grinding and mixing process ensures that the
powder is a homogeneous mixture of similar sized particles.
The Grinded powder is then packed in the storage boxes ready for shipment.
 Flaker:
Sometimes it is the requirement of the consumer that the cake solution is provided to the market in the form of
flakes. This is done by means of a flaker. The flaker is basically a rotary drum with cooling tubes. The hot cake
solution is taken from the vessel and flown on the rotary drum surface. As the drum rotates the cooling caused
by the cooling water causes it to solidify. The cake is gets stuck to the rotary drum and is scraped of in form of
flakes by means of a flaker.

30. Page | 30
Unit 2 Utilities:
Unit 2 utilities consist of:
1. Raw Water
2. Soft Water
3. Ice Making Plant
4. Furnace
5. Cooling Tower
 Raw Water:
Raw water is a raw material for water softening and a chemical reactant for the reaction in the kettle vessels.
Water is pumped through the ground by means of a turbine pump and stored in a container.
 Soft Water:
Raw water contains a large amount of TDSs and hardness creating minerals which have to be removed because
soft water is required as an ingredient in reactions, it is also used in the cooling tower to create cooling water
and is a major raw material for Ice making.
Raw water is treated with Caustic Soda to convert it into soft water, the TDSs are converted into precipitates.
 Ice making Unit:
Soft water is taken into container boxes. Cooling agent is Ammonia, the gas is compressed by means of a
Positive Displacement Compressors. There are two compressors installed, one of them is in action while the
other one is on standby. The Cooled gas flows in tubes surrounding the ice molders. This causes the soft water
to freeze into ice. Ice is an ingredient of the batch recipes.
 Furnace:
A fire tube furnace is used to heat the heating oil. Gas is ignited in the shell side of the furnace while oil flows
throw the tube side. The heat radiated from the shell causes the heating oil to heat up. The maximum
temperature of the oil is around 260 Degrees Celsius if the temperature exceeds this level the furnace trips off.
 Cooling Tower:
A forced draught cooling tower is used to cool the soft water. This cooling water is used in kettle tubes and the
condenser installed at the top of each kettle reactor.