CRACKING FURNACE (HF-301 A/B):

Prepared By : S.M.Waqas ul Hassan

P a g e | 1

TABLE OF CONTENTS

Sections Page

VCM Plant Introduction .............................................................................................02

Overall Process Description ......................................................................................02

Furnace Process Description ....................................................................................04

Process Chemistry ....................................................................................................05

By Product Formation ...............................................................................................06

EDC Feed Composition ............................................................................................08

Furnace Specification................................................................................................09

EDC Cracking Furnace .............................................................................................10

Radiant Section .........................................................................................................11

Convection Section ...................................................................................................12

Furnace Stack ...........................................................................................................14

Side Wall Burner .......................................................................................................15

Burner Wall Insulation ...............................................................................................17

Roof and Side Wall Insulation ...................................................................................18

Furnace Operating Variable ......................................................................................19

Key Ranges To Maintain Product Quality ..................................................................20

Consequences Analysis ............................................................................................21

Trouble Shooting .......................................................................................................21

Emergency Handling Procedures ..............................................................................22

Furnace Shutdown Logic ..........................................................................................25

DCS & Architecture ...................................................................................................26

ESD Architecture ......................................................................................................27

Mechanical Drawing ..................................................................................................28

P a g e | 2

INTRODUCTION TO VCM PLANT

VCM plant at this site is relocated plant from Formosa Plastics Corporation, Baton Rogue, LA,

USA. It is world 2nd relocated VCM plant and Pakistan 1st VCM plant. FPC operated this plant till

2002-2003 and then shutdown it due to economic considerations. VCM is raw material of PVC,

which is a growing industry in this region.

EDC plant technology belongs to Stauffer and VCM to BF Goodrich, now both belong to Ineos

Vinyls

Name Plate Capacity: EDC = 230 KTA (690 MT/day)

VCM = 203 KTA (610 MT/day)

Raw Material: Ethylene & Chlorine

Process Units: Total 04 Direct Chlorination to produce EDC Oxy hydro Chlorination to produce EDC EDC Cracking to produce VCM EDC purification Unit Supporting Units: Vent Gas Incineration Waste Water Treatment Scrubber

OVERALL PROCESS DESCRIPTION

Direct Chlorination Ethylene and chlorine combine in a homogeneous catalytic reaction to form EDC. Ferric chloride is the catalyst used. Reaction takes place at temperature of 55 oC at 150 KPa pressure. This is an exothermic reaction and heat removal is accomplished by cooling water.

C2H4 + Cl2 C2H4Cl2 ∆H= -79,100 Btu/lbmol

In Oxy Chlorination: Ethylene is reacted with hydrochloric acid, recycled from EDC cracking, to produce more EDC, thereby consuming every molecule of chlorine. Air is injected as source of oxygen Reaction takes place in gaseous phase, at about 204 oC and 551.5 KPa in a fluidized bed reactor, charged with cupric chloride (CuCl2) catalyst. Heat of reaction is removed by generating low pressure, saturated steam at 1034 KPa.

C2H4 + 2HCL + ½ O2 C2H4Cl2 + H2O ∆H= -104,000 Btu/lbmol of EDC

Water is separated from EDC and sent to wastewater treatment via stripping, to recover EDC. Crude EDC is sent to storage. Gaseous streams, containing chlorinated hydrocarbons, are sent to Incinerator prior to their emission into atmosphere. Crude EDC is purified in a series of distillation processes, where water, light ends and heavies are separated. Dry purified EDC is

P a g e | 3

then fed to Cracking Unit for VCM production where it decomposes into VCM and hydrochloric acid as follows

C2H4Cl2 C2H3Cl + HCL ∆H= -30,500 Btu/lbmol

Cracking temperature is 537oC. Conversion efficiency is 56-60%. Reaction products and un-reacted EDC are cooled immediately in quench section to minimize coking and reaction reversal. Hydrochloric acid is separated from EDC and VCM, and sent to Oxy Chlorination Unit. Subsequently, EDC is separated from VCM and recycled. VCM is sent to Storage.

P a g e | 4

FURNACE PROCESS DESCRIPTION

The process is based on the thermal decomposition of EDC to yield vinyl chloride (VCL) and hydrogen chloride (HCL).The pyrolysis reaction takes place at elevated temperatures and pressure in the tubes of a gas-fired cracking furnace. The gaseous reaction products are rapidly cooled and partially condensed by quenching with cooled liquid EDC and VCL in a quench column. The quench column liquid and vapor exit streams are fed to the cracking purification section and separated into product VCL, HCL, and un-reacted EDC by fractional distillation. The un-reacted EDC is purified by fractional distillation. The un-reacted EDC is purified by fractional distillation and recycled back to the pyrolysis furnace. The HCL is consumed in the Oxy-hydro-chlorination production of EDC. The furnace is operated to give about 50 percent conversion of EDC (32% VCL, 18% HCL & 50% EDC) per pass with an overall efficiency of about 96 percent conversion of EDC to VCL and HCL after distillation. The process produces VCL of at least 99.9 percent purity and HCL of at least 99.5 percent purity.

The pyrolytic cracking of EDC to VCL and HCL takes place in the radiant section of the cracking furnace. The furnace burners heat the furnace walls to approximately 871-982oC and the walls in turn supply heat evenly to the reaction coil. EDC is supplied from the furnace feed drum as a clean, dry solid-free feed which is fed to the furnaces by high pressure 3447~4136 KPa, steady-flow pumps. The rate of feed to the furnaces is controlled by flow controllers. The EDC enters the top pass of the convection section and flows downward through the coil. It is heated to approximately 248 oC in the convection section. In the radiant section, the EDC vapor is superheated and subsequently cracked at 493 oC to 507 oC, depending on the desired conversion. These temperature correspond to the normal furnace feed rate of 37194.6 Kg/hr. Conversion of 40 to 65 percent can be obtained in the cracking furnaces. It is desirable, however, to limit conversion to 53 percent since by-product and carbon formation (coil coking) increases at high conversion. "Coil coking" is a term describing the gradual deposit of carbon in the furnace tubes, mostly in the vaporization section. The carbon is removed periodically by sand jetting, a technique propelling soft metal pellets with high pressure nitrogen.

At a given conversion, by-product formation and coking increase with higher pressure. For this reason, coil exit pressure is limited to 1861 KPa to retard by-product formation and coking.

Fuel gas is fed to the burners through a flow recorder, a field solenoid valve, a HIC valve and a flow trim valve actuated by the furnace exit temperature. The HIC and flow trim valve operate parallel to the flow. Major adjustments are made by the HIC valve while minor adjustments are made automatically by the flow trim valve. The solenoid valve is closed by high and low pressure switches in both the furnaces gas feed line and the EDC feed line to the furnace. High temperature switches on the quench vapor exit and in the process exit rises inside the furnace, will also close the solenoid valve, in order to protect against overheating of the furnace box and tubes in the event of an EDC feed failure. Steam snuffing connections have been provided for

P a g e | 5

injecting steam into the fire box in case of a tube rupture. The block valves for controlling the steam snuff are located fifty-feet away from the furnaces for safe access.

The exit gas from the furnace coil consists of about 34 percent EDC, 33 percent VCL and 33 percent HCL by volume. This gas passes through the furnace discharge line directly into the quench column.

PROCESS CHEMISTRY

Reaction in Cracker (HF-301 A/B)

An EDC molecule undergoes de-hydro-chlorination, forming vinyl chloride and hydrogen chloride. The reaction is endothermic and requires the input of heat to sustain it. To get acceptably rapid conversion rates an elevated temperature is needed, stoichiometrically equation may be written as:

C2H4Cl2 + Heat C2H3Cl + HCL H = 17,600 kcal/kg-mol.

(EDC) (VCM) (Hydrochloric Acid)

Reaction Mechanism

The overall radical chain reaction scheme involves four steps as shown below.

Initiation

CH2ClCH2Cl CH2ClCH2* + Cl*

(EDC molecule) (Chloroethylene radical) (Chlorine radical)

The reaction sequence begins with the splitting of the C-Cl bond to form chloroethyl and chlorine radicals.

Chain Propagation

Cl* + CH2ClCH2Cl CH2ClCH

*Cl + HCL

(Chlorine (EDC molecule) (dichloroethyl) (Hydrogen

radical) radical) chloride)

CH2ClCH*Cl CH2 = CHCL + Cl

*

(Dichloroethyl Radical) (Vinyl Chloride Monomer) (Chlorine radical)

Chlorine radicals react with EDC molecules to form the intermediate dichloroethyl radicals which in turn eliminate chlorine radicals to form vinyl chloride molecules and propagate the chain. It is seen from these reactions that the overall effect is to convert EDC to vinyl chloride and HCL.

Termination

Cl* + CH2ClCH2

* CH2 = CHCL + HCL

(Chlorine (chloroethyl (vinyl chloride) (hydrogen

radical) radical) molecule) chloride)

P a g e | 6

The chain is terminated by the recombination of radicals. Chain propagation depends on the formation of chlorine radicals and therefore any other molecule that generates them acts as a cracking promoter. Conversely any species that consumes chlorine radicals without simultaneously producing either di-chloro-ethyl radicals or chlorine atoms is an EDC cracking inhibitor. The best known cracking promoters are chlorine itself and carbon tetrachloride. Many of the impurities in the EDC feed act as cracking inhibitors and that is why their concentrations must be reduced to low levels.

BY-PRODUCT FORMATION

The amount of by-products (and coke) produced increases rapidly in non-linear fashion as the reaction temperature and depth of crack increase. Since some of the by-products act as inhibitors to the free radical sequence increasing cracking severity leads to progressively smaller increases in EDC conversion.

Numerous by-products are formed in the furnace tubes. Four categories of components may be identified according to the mechanism by which they are produced.

Pyrolysis in Feed Impurities

Certain saturated components containing at least two carbon and two halogen atoms can Pyrolysis to the unsaturated equivalents by mechanisms entirely analogous to the pyrolysis of EDC. The following compounds may be formed in this way:

Vinyl bromide

C2H4Cl Br C2H3Br + HCL

Cis and trans dichloroethylene

C2H3Cl3 C2H2Cl2 + HCL

Trichloroethylene

C2H2Cl4 C2HCL3 + HCL

Perchloroethylene

C2HCL5 C2Cl4 + HCL

It is assumed that feed components that are already unsaturated and those that only have one carbon atom (chloroform and carbon tetrachloride) pass unchanged through the furnace tubes.

Vinylic By-Products

The vinyl chloride molecule is very stable but above about 232oC it does undergo some decomposition by splitting into vinyl and chlorine radicals. The vinyl radical (CH2 = CH*) can then combine with other C2 molecules to form a wide range of C4 compounds. The most important of these are:

Chloroprene - 1: CH2CHCH = CHCL

Chloroprene - 2: CH2CH = CClCH2

Dichlorobutenes: C4H6Cl2

P a g e | 7

Trichlorobutanes: C4H7Cl3

More heavily chlorinated species cannot be separately identified but are classified as tars and coke.

Acetylenic By-Products

The vinyl radical may combine with chlorine radical to eliminate a molecule of HCL and form acetylene:

CH2 = CH* + Cl* C2H2 + HCL

Acetylene is a significant by-product and may give rise to other species by various combinations. Those that can normally be identified are:

Benzene

3 C2H2 C6H6

Monovinyl acetylene

2 C2H2 C4H4

Monochlorobenzene:

C6H6 + 2Cl* C6H5Cl + HCL

An alternative mechanism for the production of mono vinyl acetylene is the pyrolysis of chloroprenes:

C4H5Cl C4H4 + HCL

Ethylenic by-products

These mechanisms are the least well understood but it seems that a small proportion of the chloro-ethyl radicals (formed as the initiation step in the pyrolysis of EDC) can split off a chlorine atom and produce the ethylenic radical (CH2 = CH2

*). In turn this can give rise to the following by-products:

Ethylene: CH2 = CH2

Butadiene: CH2 = CH CH = CH2

1,1-dichlorethane: CH3CHCL2

Methyl chloride: CH3Cl

The component ethyl chloride can undergo similar reactions at high temperature to produce ethylenic radicals and this explains why high butadiene concentration in the furnace outlet normally correlates with high levels of ethyl chloride in the EDC feed stream.

P a g e | 8

Chlorination of Chloroprenes

Chloroprenes (1- and 2-isomers) are formed in the EDC cracking furnaces by addition of two vinyl radicals. The alternative names for these compounds are:

Chloroprene-1 1-chlorobutadiene-1, 3.

Chloroprene-2 2-chlorobutadiene-1,3

There is a tendency for chloroprenes to polymerise, especially at high concentration and in the presence of moisture and iron and this is a major cause of the fouling of vaporisers and cracking furnace tubes. The relatively high concentration at the top of the lights column can lead to fouling of the condenser, top trays and overhead piping.

EDC FEED COMPOSITION

Ethylene Dichloride fed to the cracking furnaces should have the following approximate composition:

EDC 99.4 %w/w min.

Ethyl Chloride 20 ppm. w/w max

Cis & Trans-dichloroethylene 300 ppm w/w max

1,1-dichloroethane 100 ppm w/w max

Chloroprene 50 ppm w/w max

Chloroform 400 ppm w/w max

Carbon tetrachloride 50 ppm w/w max

Benzene 2000 ppm w/w max

Trichloroethylene 3500 ppm w/w max

Bromochloroethane 100 ppm w/w max

Beta trichloroethane 150 ppm w/w max

Perchloroethylene 50 ppm w/w max

Tetrachloroethane 50 ppm w/w max

C3 compounds 10 ppm w/w max

C4 compounds (heavies) 20 ppm w/w max

Iron 0.5 ppm w/w max

Water 40 ppm w/w max

P a g e | 9

FURNACE SPECIFICATION

HF-301A/B SPECIFICATIONS

FURNACE TYPE CABIN , BOX TYPE FURNACE

RADIANT SECTION HIEGHT 23’11’’

RADIANT SECTION WIDE 11’ 7.5’’

RADIANT SECTION LENGTH 55’

CONVECTION SECTION HIEGHT 25’2 1/8’’

CONVECTION SECTION WIDE 8’ 6.5’’

CONVECTION SECTION LENGTH 39’9’’

CONSTRUCTION LINED CARBON STEEL

FURNACE BURNER ROWS 4 ROWS BOTH SIDES

BURNERS IN 1 ROW 9 BURNERS ON BOTH SIDES

TOTAL BURNERS 72 BURNERS

RADIANT COILS 32

COILS OD, SCH 6.625”, 80

RADIANT TUBES LENGTH 51' 10".

UPPER CONVECTION SECTION TUBES 40

TUBES OD, SCH 4.5”, 40

UPPER SECTION ROWS 8 ROWS, 6 TUBES/ROW

LOWER CONVECTION SECTION TUBES 32

TUBES OD, SCH 6.625”, 80

LOWER SECTION ROWS 4 ROWS, 8 TUBES/ROW

CONVECTION SECTION ROWS LENGTH 39 ft

P a g e | 10

EDC CRACKING FURNACE (HF-301A/B)

The cracking furnaces are cabin type furnaces consisting of a radiant section and convection section. The lower section of the furnace is the radiant section which is 23'11" high, 11' 7 1/2" wide, and 55' long. The convection section which is 25' 2 1/8" high, 8' 6 1/2" wide, and 39'9" long, is the upper section of the furnace. Both furnaces are constructed of carbon steel lined with cast able refractory. The furnace walls have four rows of equally spaced natural gas burners capable of delivering 110,000,000 BTU/hr. Each row consists of 18 burners, nine on each side of the furnace.

P a g e | 11

RADIANT SECTION:

The cracking furnaces are cabin type furnaces having radiant section consist of 32 6.625" OD Sch 80 tubes connected in series and positioned in a dual vertical plane midway between the two radiant furnace walls. These tubes are constructed of a carbon steel alloy and each has an effective length of 51' 10". The tubes are heated by radiation from the burners and the hot walls

P a g e | 12

CONVECTION SECTION:

The convection section is located above the radiant section where it is cooler to recover additional heat. Heat transfer takes place by convection here, and the tubes are finned to

increase heat transfer. The first tube rows in the bottom of the convection section and at the top of the radiant section is an area of bare tubes (without fins) and are known as the shield section, so named because they are still exposed to plenty of radiation from the firebox and they also act to shield the convection section tubes, which are normally of less resistant material from the high temperatures in the firebox.The convection section coils are heated by convection

from the combustion products passing out the top of the furnace. The tubes in this section are equipped with fins to enhance absorption of heat. In the upper section of the convection furnace, there are 48 4.5" OD Sch 40 tubes arranged in 8 rows with 6 tubes per row. The lower section has 32 6.625" OD Sch 80 tubes arranged in 4 vertical rows with 8 tubes per row. The effective tube length of each section is 39.0 ft.

P a g e | 13

P a g e | 14

FURNACE STACK:

The flue gas stack is a cylindrical structure at the top of all the heat transfer chambers. The breeching directly below it collects the flue gas and brings it up high into the atmosphere where it will not endanger personnel.

The stack damper contained within works like a butterfly valve and regulates draft (pressure difference between air intake and air exit) in the furnace, which is what pulls the flue gas through the convection section. The stack damper also regulates the heat lost through the stack. As the damper closes, the amount of heat escaping the furnace through the stack decreases, but the pressure or draft in the furnace increases which poses risks to those working around it if there are air leakages in the furnace,

the flames can then escape out of the firebox or even explode if the pressure is too great

P a g e | 15

SIDE WALL BURNERS

Both cracking furnaces have side fired burners. The burner tile is made of high temperature refractory and is where the flame is contained. Air registers located below the burner and

classified as primary, secondary. The primary air register supplies primary air, which is the first to be introduced in the burner. Secondary air is added to supplement primary air. Burners include a pre-mixer to mix the air and fuel for better combustion before introducing into the burner. The furnace walls have four rows of equally spaced natural gas burners capable of delivering 110,000,000 BTU/hr. Each row consists of 18 burners, nine on each side

of the furnace

P a g e | 16

BURNER WALL INSULATION

INS BLOK 19

Mineral Wool, Block Insulation INSBLOK-19 is 1900°F maximum service temperature lightweight mineral wool block insulation. INSBLOK-19 exhibits very low thermal conductivity, good moisture resistance, easy handling, and easy cutting. Its organic binder gives INSBLOK-19 excellent cold strength but will dissipate above 475°F. INSBLOK-19 meets the ASTM C612 Class 5 specification. Its principal application is as a backup lining to lower furnace shell temperatures.

IFB 2300

2300°F Insulating Firebrick, applications of IFB 2300 LI is suited for both backup and hot-face lining duty. Typical applications include ceramic kilns and backup linings in iron channel induction furnaces and sulphur recovery units.

P a g e | 17

ROOF AND SIDEWALL INSULATION

INSWOOL HP BLANKET

2300°F Alumina-Silica Ceramic Fiber Blanket INSWOOL-HP BLANKET was developed to meet the demand for a high temperature, flexible blanket insulation with a low iron content of less than 1%. INSWOOL-HP BLANKET has excellent strength, both hot and cold. It remains in place on the furnace anchors even at high temperatures and can resist damage even when subjected to normal mistreatment in shipment and handling. If INSWOOL-HP BLANKET becomes wet from water, steam, or oil, its thermal and physical properties are restored upon drying. Its sound absorption ability is greater than dense or insulating refractories and it stores some 95% less heat than dense firebrick and about 75% less than insulating brick.

FLOOR LAYERS:

KAST-O-LITE

2000°F Insulating Castable Features:

Ultra-lightweight castable with low thermal conductivity and good strength.

Can be cast or gunned. Uses

Lightweight panel construction.

Flue and duct linings, complete monolithic linings.

Backup material.

EMPIRE S

High Duty, Dry Press Fireclay Brick. EMPIRE S is an economical high duty fireclay brick meeting ASTM regular type classification. It is suitable for boilers, dense brick backup linings, air heaters, and other areas encountering moderate operating temperatures. Not suggested for abrasive conditions.

P a g e | 18

FURNACE OPERATING VARIABLE

Operating

Variables

Optimum Values Consequences

Furnace

Temperatur

e

37194.6 Kg/hr

Exit

temperature

501 oC

Min feed rate

14288.2 Kg/hr

(33% of design)

and 482 oC

The temperature will be varied somewhat depending on the EDC feed rate to the furnace and the purity of the EDC feed. This is done to maintain proper conversion and to keep coil coking at a minimum, although the minimum temperature is generally kept at 490 oC

The minimum feed rate on both furnaces is dependent on the minimum HCL feed on the Oxy-chlorination Reactor.

High coil exit temperature will shut down the furnace automatically.

Furnace

Pressure

Inlet pressure

3447 to 3619

KPa

Outlet Pressure

2000- 2275 KPa

Pressure is controlled by the pressure control valve on the vapor line from the quench vapor separator to the HCL column.

This pressure should be maintained as steady as possible, to ensure smooth operation in the cracking furnaces.

Pressure will increase as the tubes gradually coke up.

When the inlet pressure rises to 4136 ~ 4343 KPa, the furnace must be shut down and de-coked. This decoking is necessary to prevent plugging or over pressurizing the furnace tubes.

Automatic shutdown of the cracking furnaces will occur with high and low coil inlet pressure 4481 KPa and 2758 KPa respectively.

Furnace

Feed Stream

Moisture < 40 ppm.

Lights content < 350 ppm

Benzene and

heavies

It is essential that water and lights (low boiling hydrocarbons) in the EDC be kept within the product EDC specifications. Water in the cracking unit is especially damaging, since it combines with gaseous HCL to form muriatic acid, which can cause heavy corrosion throughout the system.

High lights content above 350 ppm in the furnace feed are harmful in that it causes higher coking rates in the furnace tubes. This in turn requires that the furnaces be shut down and decoked more frequently.

Impurities decrease in conversion rates in the furnaces.

Furnace

Fuel

Natural Gas ,

Hydrogen Gas

Gas be of uniform quality and even burning. Impurities and fluctuations in the natural gas feed can cause temperature fluctuations in the furnace.

Low or high pressures in the natural gas feed will shut down the furnace by automatic control.

P a g e | 19

KEY RANGES TO MAINTAIN PRODUCT QUALITY

COMPONENTS NORMAL RANGE

1,2-EDC (%) 99.1 - 99.5

Ethylene Not normally present

VCM (ppm) Traces only

Ethyl chloride (ppm) 0~20

Cis, trans & 1,1-EDC (ppm) 300~800

chloroform (ppm) 1500~2500

chloroprene (ppm) 100~200

CCL4 (ppm) 500 - 1500

Benzene (ppm) 2000~3000

Trichloroethylene (ppm) 2000~4000

1,1,2-trichloroethane (ppm) 30~100

Per & tetra (ppm) 30~100

Moisture 30~45

Fe 0.5~2

pH Dry system

P a g e | 20

CONCEQUENCES ANALYSIS

COMPONENT ROOT CAUSE FOR ABNORMAL RANGE CONSEQUENCES

1,2-EDC Low = high levels of other impurities Fouling of cracking furnaces

Ethyl chloride High = poor separation in Heads Column Butadiene in VCM product

Cis, trans & 1,1-

EDC

High = poor separation in Heads Column Fouling of cracking furnaces

Chloroform

High = poor separation in Heads Column Fouling of cracking furnaces

Chloroprene High = poor separation in Lights Column Severe fouling of cracking

furnaces

CCL4 High = poor separation in Heads Column Enhanced cracking in furnace

1,1,2-

trichloroethane

High = poor separation in Hiboil Column Fouling of cracking furnaces

Per & tetra High = poor separation in Hiboil Column Fouling of cracking furnaces

Moisture High = poor separation in Heads Column Downstream corrosion

Fe High = high corrosion due to high

moisture content

Severe fouling of cracking

furnaces

pH Dry acidity (HCL) is not a problem

P a g e | 21

TROUBLE SHOOTING:

PROBLEMS POSSIBLE CAUSES ACTIONS

Low flow

PP-407A/B Low flow

Trip on high amps

Furnace coking

High quench pressure

Check furnace feed drum level MS-403, may be Level transmitter malfunctioned Earthing or grounding fault, immediately start stand by pump for hot startup of furnace Check conversion rate, reduce cracking rate if possible Confirm PIC-315 valve opening from field.

High flow FIC-301A/B maximum

open

Confirm valve opening from field

Low oxygen

Malfunctioning of Damper Improper burning. Fuel pressure too high Tube Rupture

Confirm damper opening in field. Check burner air register opening. Confirm damper opening from DCS, may be low opening Choked burners pulled and repaired Check NG pressure on DCS Immediately shutdown furnace and purge

High oxygen

Malfunctioning of Damper Improper burning. Fuel pressure too low

Furnace peep hole

Confirm damper opening in field. May be too high Check burner air register opening. Confirm damper opening from DCS, may be high opening Choked burners pulled and repaired Check NG pressure on DCS Close all peep holes of furnace adjust air to burner.

P a g e | 22

opening

Furnace exit

temperature

Low

Natural gas low pressure Burner extinguish High EDC flow to furnace

Increase NG pressure. Check burners’ condition and light up if in case extinguished. Confirm FV-301A/B opening through field Put FIC on manual and throttle through field.

Furnace exit

temperature

High

High NG pressure Low EDC flow to furnace

Check PV-312 opening Confirm FV-301A/B opening through field Put FIC on manual and open through field. Check MS-403 level, may be too low Check PP-407A/B pump

EMERGENCY PROCEDURE:

a) Cracking Furnace Tube Rupture:

Indications

O2 content will decrease sharply.

Dark Plume from furnace stack.

Furnace feed flow will increase.

Draft will change to +ve value from –ve.

Fire box temperature abnormal increase.

Low furnace outlet temperature.

Increase in stack temperature

P a g e | 23

NOTE If O2 content goes below 2% and same time furnace draft goes to positive value, immediately shutdown

the furnace by actuating I-4 & I-5

Actions:

Actuate emergency shutdown by I-4 / I-5 and make furnace shutdown.

Fully open furnace stack damper.

Close furnace feed control valve immediately.

Close HIC-311 A/B and open HIC-602 C/D (vent valve to VGS) and depressurize the Quench to VGS.

Open N2 in the furnace coil when pressure is below N2 header pressure.

Declare emergency as per assessment by fire squad leader. Fire squad to contain the fire by water curtain and keep quenching the surrounding area.

NOTE

In case of tube failure/ fire in one furnace, Shutdown both furnaces, after taking consent from Site

Coordinator

If circulation & filtration pumps are working and area is accessible, divert quench to off bullet and transfer liquid to bullet until pump loses suction.

Stop both filtration and circulation pumps.

b) TT-300A/B (QUENCH CIRCULATION COOLER) TUBE RUPTURES:

Indications

Decrease of PH valve at analyzer AI-305 A or AI-303 B.

Decrease in Quench circulation flow at FI-305 A / FI-305 B but increase in pumps amps on PP-300 A/B and PP-313 A/B.

Increase in bottom temperature of AS-301 A/B at TI-1-82 / TI-1-88.

Leak in CWS/CWR flanges elbows at TT-300 A/B.

Low pH indication of rest pH analyzers on CW system.

Decrease in pH of CW at cooling tower.

P a g e | 24

Discoloration of C/W with EDC and HCL smell in it. Consequences

HCL / VCL / EDC slippage to CW system i.e. contamination in whole CW system of site.

Corrosion effects on other exchangers.

Reliability effects of CW system and other exchangers. Actions

Verify leakage through local Ph monitoring of CWR / send sample to lab.

Isolate CWS / CWR.

Furnace A/B shutdown by actuating I-4 / I-5.

Isolate TT-300 A/B process side.

Continue EDC circulation to cool down the furnace.

Continue filtration pump operation

Isolate HIC-311A/B.

CAUTION:

Control Quench O/H pressure via bleeding toward VGS through HIC -602 C/D.

Stop EDC circulation one Furnace Temp get below 260 0C.

Close LV-302B and make isolation.

Depressurization to VGS and bring down pressure 50 – 60 kpa

Depressurize the tube side of exchanger toward crack gas header; install nitrogen hose to keep exchanger at higher pressure.

TT-300A/B shell side draining to be carried out.

Caution:

Area to be cordon off before exchanger local draining and stop all work down wind

Open water in channel at draining point for dilution effect.

Information

Immediately inform Site Manager / Section Head / UTY SIC.

P a g e | 25

HF-301A/B ESD LOGIC

P a g e | 26

DCS ARCHITECTURE

P a g e | 27

ESD ARCHITECTURE

P a g e | 28

MECHANICAL DRAWING:

P a g e | 29