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Refinery fire: Emergency response and Pre Fire plan for Delayed Coker Unit

Refinery fire: Emergency response and pre fire plan for Delayed Coker Unit


Refinery fire: Emergency response and Pre Fire Plan for Delayed Coker Unit


The Delayed Coker Unit is extremely prone to major accidents, including fires, toxic releases and explosions due to its extreme process conditions. This article provides information on the best mitigation techniques for effective emergency response by preparing a pre-fire plan and the best firefighting strategies for Delayed Coker Unit emergencies viz. fires, explosions and the release of toxic gases.
In this article, we will discuss the different emergencies, credible scenarios in the refinery Delayed Coker Unit (DCU) and how to mitigate these emergencies by improving the implementation and practice of the pre-fire plan (PFP) or the pre-incident plan (PIP). We start with the general operational process of the Delayed Coker Unit, why called DCU, what are the products of DCU, the history of DCU, how does the Delayed Coker Blow Down system work, the Hazards of DCU, the required fire protection system, emergency response planning and firefighting strategies.

Delayed Coker Unit (DCU) process in refinery



Delayed Coker Unit (DCU) process in refinery
Delayed Coker Unit (DCU) process in refinery

The objective of the Delayed Coker Unit is to convert the bottom of the barrel i.e. the vacuum residues, into valuable distillate, of petroleum coke to eliminate the production of low value fuel oil / asphalt.
The delayed coking process is a thermal cracking process intended to transform heavy petroleum residues into lighter gaseous and liquid products and into solid coke (green coke). The petroleum residue feedstock is heated in a specially designed heater at high temperature with a short residence time. Thermal cracking reactions start in the heating coils and end in coke drums (accumulator vessels with long residence time). The thermal cracking reactions in the heater are carefully controlled to minimize the build-up of coke in the heater coils. The solid product is retained in coke drum. The effluent vapor from the coke drum is quenched to stop other cracking reactions and then fractionated into various distillates and light end products.:

Key Process Steps of Delayed Coker Unit



Key Process Steps of Delayed Coker Unit
Key Process Steps of Delayed Coker Unit

  • Heating of vacuum residue to max.507 °C in Coker furnace.
  • Transfer the hot residue to coke drum before it has formed coke.
  • Fill the drum and allow the heavy tars to coke.
  • Switch the drums on timed cycle
  • De-coke the full drum hydraulically.
  • Recover the cut coke, crush and prepare for shipment.
  • Recycle water to eliminate waste.
  • Fractionate cracked products into Fuel gas, LPG, Coker naphtha, light Coker gas oil and heavy Coker gas oil.
  • Further process fractionated products in downstream units.

Delayed Coker Unit may also process refinery slop oil, refinery sludge from wastewater treatment plant, Vacuum Residue (VR) and slurry oil from FCCU.

Refinery Interface for Delayed Coker Unit (DCU)

Vacuum residue from vacuum distillation column, vacuum residue from storage and slurry oil from FCCU are fed to Delayed Coker Unit (DCU) for thermal cracking. Refinery Slop can also be processed in DCU intermittently. The cracked products i.e. unsaturated fuel Gas, Unsaturated-LPG and Coker distillates produced in DCU are sent to respective downstream units for further processing. Raw (Green) petroleum coke produced in DCU is sent to petroleum Coke handling area.


Refinery Interface for Delayed Coker Unit (DCU)
Refinery Interface for Delayed Coker Unit (DCU)

Why call delayed Coker unit

In the Delayed Coker Unit, the process is carried out in batches and the switching frequency of the drums varies from 10 to 24 hours, which is why it is called "delayed process".
The vacuum of residual feedstock from the vacuum distillation column is heated by a fired heaters and sent to the first Coker drum. At high temperature (870 to 910 ° F) and high pressure (15 to 35 psig), thermal cracking occurs and lighter fractions are sent to a fractionation column for separation of gas and other higher quality hydrocarbons. Here, heavy residues remained in a Coker drum until they reached the predominant level, then fed the second coke drum and continued to other drums. The steam is purged in the Coker drum to remove traces of residual oil, then the rooster is cut by hydro jet, followed by cooling of the drum called decoking. The coke then fell to the bottom and then with a fixed crane bucket, it is transferred to a Coke pit. After decoking the drum, it is closed, purged of the air tested for leaks, then reheated and ready for the next batch operation to repeat the cycle. Therefore, this process of producing petroleum coke is called the Delayed Coking Process and the plant is the Delayed Coker Unit.
The Delayed Coker Unit is composed of the following sections
  • Feed Surge Drum and Feed Preheat
  • Heaters and Coke Drums
  • Primary Fractionation
  • Vapor Recovery Section
  • Amine treating Section
  • Coke Drum Steam-out / Blow-down
  • Coke Handling unit/ yard

Products of delayed Coker unit

1.      Unsaturated Fuel Gas
2.     Unsaturated LPG
3.     Coker Naphtha
4.    Light Coker Gas Oil
5.     Heavy Coker Gas Oil
6.    Heavy-Heavy Coker Gas Oil
7.     Green Coke

History of Delayed Coker Unit

Heavy crude oils have long chain carbon and hydrogen molecules than lighter crudes. This heavy crude was readily available in most Gulf countries, Russia, the United States, etc. After the refining of this heavy crude oil, the end product (bitumen / asphalt) sold as an industrial raw material of relatively low value for the construction of roads, roofing tiles or for an additional process of extraction of higher value products. Since it was not economically profitable for refiners.
Then, new technology comes to process this heavy refinery end product to extract other valuable products and convert the final product into a valuable product like petroleum coke. It is the popular process for upgrading heavy ends is the Delay Coker process. In this process, a very high temperature is required to create thermal cracking of the heavier stock for an extended period of time.
This thermal cracking process produces higher value products such as LPG, unsaturated feul gas, unsaturated LPG, Coker naphtha, light Coker Gas Oil and Heavy Coker Gas Oil and, finally, the residues are solid carbonaceous “Coke”.
This technology first appeared in the United States in 2003 and now the Delayed Coker Unit is found in almost every refinery in the world.

Delayed Coker blowdown system

A Delayed Coker Blowdown system (CBD) is provided to recover hydrocarbon and water residues generated during the decoking process in the Coker drum. During the coke bed cooling process, the water is superheated, vaporized and condensed. This condensed water separated from light gas and oil in three phases in a separator vessel. Water contains dissolved hydrogen sulfide (H2S) and ammonia gas (NH3). The main purpose of delayed Coker blowdown system is to recover this water and return it to the refinery's sour water stripper tower for further treatment and reuse.
It is also useful for minimizing toxic exposure to people and for protecting the environment.

Hazards of Delayed Coker Unit (DCU)

Below are the major hazards of Delayed Coker Unit
·        Fire Hazard- Jet Fire/Pool Fire/Flash Fire
·        Toxic Release
·        Explosion –UVCE/VCE
·        Hydrocarbon Leak & Spill
·        Hazardous Chemical Leak
·        Electrical Fire
·        High pressure and high temperature
·        Coke dust hazard
Other than above QRA hazards, below specific operational hazards may be considered for prevention of incidences.
Specific operation hazards
Coke drum switching, removal of Coke drum-head, Coke cutting (hydro-jet operation), General and emergency and operational hazards, hazards during Coke transfer, processing and storage, emergency evacuation, dust exposure, toxic gas exposures, etc
Individual risk contour for Delayed Coker Unit
Ref. Quantitative Risk Assessment (QRA) of the Delayed Coker Unit and take the risk level into account when preparing the emergency response plan and developing a pre-fire plan. The pre-fire plan can be prepared by the fire department in consultation with the operations team.

Fire protection in a refinery Delayed Coker Unit

When designing fire protection systems, the height of the Coker drum, the number of Coker drums and the separation distance of the whole unit from adjacent units such as VGOHT or DHDT or ISOM should be taken into account. The static pressure of the fire water must also be taken into account in the design of the long-range monitor and the medium-speed water spray system. Here we are considering a delayed Coker unit with 4 Coker drums. When preparing the pre-fire plan, the total number of fire protection systems must be taken into account with their identification / tagging.
·     Fire Hydrants = ___Nos
·     HVLRM (2000 GPM) = ___Nos
·     Water cum foam monitors = ___Nos
·     Water spray systems (DV) = ___Nos
·     Water spray systems (manual MVWS) = ___Nos
·     Manual Call points = ___Nos
·     Fire Extinguishers = ___Nos
·     Foam Trolley = ___Nos
·     Hose Box = ___Nos
·     Booster Pumps for tower monitors: ___ Main pumps & ___ Jockey Pumps
·     Clean gas system for satellite buildings and control room ___Nos

Credible Emergency Scenarios in Delayed Coker Unit

·        The major fire incident can take place in the process equipment involving the following scenarios.
·        Jet Fire / Flash fire in hydrocarbon
·        Pool fire in flammable liquid
·         Toxic release (H2S)
·        Spillage of Hydrocarbon (No fire)
·         Fire in Coke drum
·        Fire in heater (Furnace)
·        Fire in Electrical equipment

Refinery Emergency preparedness & response planning

Planning for emergency preparedness and response at a refinery is an important document developed with reference to the quantitative risk assessment (QRA), including modelling of gas dispersion.
Here in this article we discuss the emergency response plan for the Delayed Coker Unit only. We have already identified the credible scenarios for delayed Coker unit reference to QRA, then we need to examine the availability of firefighting facilities and the manpower required to manage the major risks in the DCU.

Company emergency response plan for Delayed Coker Unit - for all emergencies
The emergency response and the action plan must include the mitigation measures by the operations team, the maintenance team, the site incident controller, the security team, the firefighting crew and medical team applicable to all credible scenarios. Now we discuss here the course of action for all types of emergencies by each key member applicable to the Delayed Coker Unit.

Emergency response plan - Action by the operational team:

In the event of an emergency, by any person, activate the manual call point (MCP) nearby and simultaneously transmit the message to the operator of the control panel and operational Shift In charge of DCU plant via Walkie Talkie.
The control room panel officer must inform the respective plant manager, the chief operating officer and the manager of the refinery shift.
The DCU panel officer must inform the panels officer of neighbouring units. Then, he must make an announcement via the public address system to stop all work and evacuate the area immediately.
The operating team, including the field officer and the site manager, initiates mitigation measures based on the fire / toxic release / oil leak scenario.
Simultaneously, the operations team must initiate isolation of the equipment / pipeline / section of the locally affected unit / plant DCS panel in accordance with the requirement to control the situation.
The operation team should assist the firefighting team and the medical team by directing them to the emergency scene. They must inform the scenario, the product involved with the operating parameters. The initial firefighting or any other mitigation measure must be initiated by the operating team, viz. operation of fire extinguishers, water spray system for cooling equipment and structures, operation of fire monitors and fire hydrant, etc.
The operating team must monitor the LEL / toxic concentration during the emergency and after completion.
DCU Area Manager / Shift In charge operation must maintain constant communication with the site incident controller on the measures taken and must work under the direction of the site incident controller.

Emergency action by Site Incident Controller (SIC)

Upon receipt of the emergency call, the site incident controller must reach the incident site and assume overall command in accordance with the refinery's emergency response and disaster management plan.
Assess the situation, establish the command post in a safe place and obtain all the information on the measures taken by the area manager / shift manager, the fire commander, the security officer and the maintenance in-charge.
Depending on the situation, SIC will guide the operating team to initiate the necessary isolation or the emergency shutdown of plant, if necessary. SIC must ensure that all of the above emergency actions have been taken by the operations team.
The SIC will take all relevant information from the fire commander and decide on the strategy to follow in consultation with Head-Fire services for additional resources, calling for mutual aid and adopting alternative methods to mitigate the emergency.
The SIC must ensure that the area is barricaded, that the movement of vehicles is restricted, that evacuation and enumeration at the assembly point are done by security team.
The SIC must request the maintenance team to perform a maintenance activity to stop the leak in accordance with their standard operating procedures.
He must ensure that the injured person has been transferred to the health center and also ensure the availability of first aiders and auxiliary firefighters.
The SIC must initiate an adequate level of emergency siren after discussion with the chief incident controller (Refinery Head).
He is responsible for declaring "All Clear" after ensuring the safe mitigation of the emergency. Before declaring “All Clear”, he must assess the situation for damage and the environmental / toxic level.

Emergency mitigation action by Maintenance Team

The maintenance lead must ensure that the maintenance team immediately reaches the incident site with the necessary non-sparking tools and resources in accordance with their standard operating procedures and initiates the action line in accordance with safe maintenance practices.
Maintenance in charge must report to the SIC and issue directives for the continuation of the maintenance activities to be carried out.

Emergency action by Security Team:

The security officer must report to the incident site immediately after receiving an emergency call and report to the site incident controller.
They must delimit the area and restrict the movement of non-essential people. They must regulate traffic and authorize only emergency vehicles on the emergency site.
Ensure an orderly evacuation to the assembly point. A security officer counts the workforce and rebroadcasts it to the site incident controller.
All emergency team leaders must ensure the safety of their team members and mandatory PPE is used.
So far, we have discussed the general course of action of all key personnel to mitigate any type of emergency in the Delayed Coker Unit. Let's start specific emergency mitigation measures for specific types of emergencies, as noted above.

Pre fire plan for refinery

A pre-fire plan or pre-incident plan is prepared to effectively mitigate any emergency in order to minimize loss. Generally, the pre-fire plan is developed by emergency responders such as fire and rescue services. NFPA 1620 provides detailed guidelines for developing pre-fire plans to assist emergency responders in effectively mitigating emergencies. When developing the pre-fire plan, it is necessary to ensure the protection of plant peoples, emergency response personnel, property and the environment.


Refinery Pre fire plan documents

Refinery pre-fire plan must be prepared for a specific machine / equipment / column, / vessel or structure in a specific unit of refinery with reference to the QRA. It must be documented and guarantee its accessibility to all emergency responders. It can be communicated at the refinery unit level for better understanding and to reduce the response time of emergency responders.
The important points below must be taken into account in the documents of the pre fire plan.
Data collection: QRA report and list of credible scenarios for specific equipment.
Scope: When preparing the pre-fire plan, the physical site condition must be taken into account.
Procedure and Templates: The procedure for developing a pre-fire plan with a standard template must be finalized for standardization.
Human occupation: When preparing the pre-fire plan, the density and type of occupation and the level of exposure to a particular equipment / area must be taken into account.
Fire protection system: During the preparation of the pre-fire plan, collect all data to know the availability of existing water supply and fire protection systems
Hazard Consideration: List all possible hazards and communicate to the responders and mitigation team, including special hazards.
Emergency management action plan and strategy: finalize emergency operations, fire-fighting tactics, dilution and dispersion tactics of toxic gases / flammable gases.
Fire drill / Mock drill: Plan for pre-incident plan testing and decide the  frequency of drill, maintenance and updating of the plan.
Fire pre plan template
Here is the standard template for the pre-fire plan developed according to our experience. This template can be revised depending on the site condition. Standard NFPA 1620, latest edition 2020 can be referenced for a pre-incident template, but it is mainly applicable for building and may not be suitable for a refinery.
Click here to download


Pre fire plan for Delayed Coker Unit (DCU)

Emergency Scenarios (ref your QRA)

1. Jet Fire / Flash fire in hydrocarbon: Jet fire / flash fire can occur in the following process equipment with heat radiation ranging from 1 KW/m2 to 37 KW/m2 as per QRA report.

  • Fractionator column & other Columns
  • Stripper, Absorber & FG Scrubber
  • LPG amine contactor
  • Debutanizer
  • Heater charge pump
  • Feed Pump & Gas oil pump around
  • Other Pump around & product

Here we must list out numbers of flash fire / jet fire scenarios as per QRA study. Pre-fire plan can be prepared for all credible scenarios. Here for understanding, we are considering below major scenarios having maximum impacts. 
Equipment/process: Coker feed drum/column to Heat chargers XYZ through 24” piping.
Emergency Scenarios:
Scenario-1:  Large leak of hydrocarbon from 24’’ line, leakage rate and duration as per QRA may be 30 kg/s for 128 sec. potential event may be flash fire or/and jet fire. Here impact criteria for flash fire may be lower flammability limit. impact criteria for jet fire may be radiation 37 kw/m2 and 4 kw/m2.
Scenario-2:  Full bore rupture of 24’’ line resulted into large leak of hydrocarbon. Here release rate and duration we are considering as 9402 kg/s for 1.47 sec. Event may be flash fire, jet fire and vapour cloud explosion. Here impact criteria for flash fire may be lower flammability limit. Impact criteria for jet fire may be radiation 37 kw/m2 and 4 kw/m2 and 0.3 bar for vapour cloud explosion.
Potential consequence distance (at 3 m/s wind speed):
For scenario-1: Released hydrocarbon vapour may travel at its Lower flammability level up to 26meters and may resulted into flash fire. Up to 47 meters, heat 37 kw/m2 and at 160meter it may be 4kw/m2.
For scenario-2: Released hydrocarbon vapours may travel at its Lower flammability level up to 580 meters and may resulted into flash fire. Up to 265 meters heat 37 kw/m2 and at 825 meters it may be 4kw/m2. Vapour cloud explosion may affect upto 335 meters.


Risk level mark up in lay out drawing
Risk level mark up in lay out drawing

Emergency response and firefighting strategy by Firefighters
After receiving an emergency call, the fire team must present themselves urgently with all appropriate firefighting equipment, personal protective equipment and report to the emergency site.
While taking emergency trunout from the fire station, make sure of the wind direction, be in constant contact with the fire control room. After reaching the emergency site, the fire tender / fire engines should only be parked in the upwind / crosswind direction. The fire tender must be parked in a safe place and directed towards the exit.
Evaluate the scenario, get all the information about the emergency site from the plant shift in-charge or site incident controller and a brief final mitigation action to all firefighters.
All members of the fire crew must wear self-contained breathing apparatus (SCBA). Two firefighters must ensure the connection of the hydrant to the Fire tender for make-up water and be ready for firefighting.
The rescue operation must be launched at the initial level by two firefighters and the other firefighters must be ready for the dispersion of gas and firefighting.
Since most of the equipment in the Delayed Coking Unit is at a high temperature, the fire commander should contact the site incident controller to take decision on application of water / foam to the affected processing equipment to avoid thermal stress on process equipment / piping. If necessary, apply foam as well as DCP.
If necessary, call in for additional fire assistance and resources. If possible, cool nearby equipment using the deluge water spray (DV) system.
The fire commander should assess the situation and ask the firefighting team to use a fire suit / heat resistant suit / other specialized equipment.
Operate the groundwater monitor / tower monitor and HVLRM (high-volume long-range monitor) for water / foam application depending on the situation.
Help the operations and maintenance team to mitigate the incident. If there is a demand to close the process isolation valve which is engulf in fire, the responder must wear a fire entry suit with a water spray back-up line. These water spray must continue to provide a cooling effect to the personnel involved in closing the isolation valve.
The fire commander must ensure the continuous application of extinguishing means to control, contain and extinguish the fire. Water curtain must be provided to isolate the radiant heat, if possible. Intensive cooling of the surrounding installations must be ensured to prevent the spread of fire.
The fire chief must ensure the required fire water header pressure of the fire water system in coordination with the operator of the fire water pump house. If situation demand, the fire chief may consult the site incident controller for any further assistance from mutual aid members, the auxiliary team, etc.
All actions to mitigate the incident must be carried out under the instructions of the fire chief. Check the LEL / toxic gas level for safety of peoples with the operating team in consultation with the site incident controller.
Ensure adequate drainage of spills and take the necessary measures to eliminate any contaminated surface.
After ALL CLEAR, stop the operation of fire protection system and communicate the fire water pump house about no further demand. Ensure the restoration of all emergency fire equipment / appliances.

2. Pool fire in flammable liquid at Delayed Coker Unit (DCU)
Pool fire can occur in the following process equipment at Delayed Coker Unit as per QRA report.
  • Fractionator overhead receiver
  • Inter stage drum & Recontact drum
  • Debut overhead receiver drum
  • Rich amine & stripper surge drum
  • Heater charge pump
  • Feed Pump
  • Gas oil pump around & product
  • Heater

Here we must list out numbers of pool fire scenarios as per QRA study. Pre-fire plan can be prepared for all credible scenarios. Here for understanding, we are considering below major scenarios having maximum impacts in pool fire scenario.
Equipment/process: Rich sponge oil pipeline of 12” size from column XYZ to column ABC
Emergency Scenarios:
Scenario-1:  Large leak of hydrocarbon from 12’’ line, leakage rate and duration as per QRA may be 74 kg/s for 600 sec. potential event may be pool fire. Here impact criteria for pool fire may be pool diameter and it may be around 105 meters.
Scenario-2:  Full bore rupture of 12’’ line resulted into large leak of hydrocarbon. Here release rate and duration we are considering as 166 kg/s for 370 sec. Event may be pool fire. Here impact criteria for pool fire may be pool diameter and it may be around 125 meters.
Emergency response and firefighting strategy by Firefighters for pool fire
After receiving an emergency call, the fire team must take emergency turnout urgently with all appropriate firefighting equipment, personal protective equipment and report to the emergency site.
While taking emergency turnout from the fire station, make sure of the wind direction, be in constant contact with the fire control room. After reaching the emergency site, the fire tender / fire engines should only be parked in the up wind / crosswind direction. The fire tender must be parked in a safe place and directed towards the exit.
Evaluate the scenario, get all the information about emergency site from the operation shift in charge or site incident controller and a brief final mitigation action to all the firefighters.
All members of the fire crew must wear self-contained breathing apparatus (SCBA). Two firefighters must ensure the connection of the hydrant to the fire tender for make-up water and be ready for firefighting.
Cover the hydrocarbon pool fire, surround area and point of leak by applying firefighting foam in all directions. Use medium expansion foam generating nozzles for immediate and rapid coverage of oil spilled under fire.
The DCP can also be used to extinguish the pool fire near hot equipment. Call additional resources, if necessary.
Cool nearby equipment using a water spray system (DV). Care should be taken to avoid restrictions after applying the applied foam, otherwise this will disturb the foam cover.
Make sure there is no source of ignition about 200 meters from the pool oil, in the case of oil pull without fire. Prevent entry of spilled oil into the stormwater channel. Use a sand or oil containment boom to contain the spilled oil.
Operate the ground monitor / tower monitor and HVLRM for water -foam depending on the situation.
The fire chief may consult the incident controller for any mutual aid assistance requirements, auxiliary team, etc. Check the LEL / toxic gas level.
Ensure adequate drainage of spills and take the necessary measures to eliminate any contaminated surface. Ensure the restoration of all fire systems and emergency equipment.

3 Toxic release (H2S) at Delayed Coker Unit (DCU)
Following equipment & connected piping are prone to toxic release as per QRA study.

  • Fractionator overhead condenser
  • Wet gas compressor
  • Stripper & Absorber
  • Flue Gas Scrubber
  • LPG amine contactor
  • Debutanizer
  • LPG & Naphtha pump


Toxic release scenarios may have major impact as mentioned below as per QRA study.
Equipment/process: Overhead vapour pipeline of 60’’ size from XYZ column to heat exchanger (specific exchanger number should be mentioned)
Emergency Scenarios:
Scenario-1:  Large leak of vapour from 60’’ line, release rate and duration as per QRA may be 1225 kg/s for 7 sec, Here vapor/ gas can be travel and form vapour cloud upto 1120 meters distance by consideration of consequences at 3 m/s wind speed.
Scenario-2:  Full bore rupture of 60’’ line, release rate and duration as per QRA may be 2865 kg/s for 0.03 sec, Here vapor/ gas can be travel and form vapour cloud upto 1350 meters distance by consideration of consequences at 3 m/s wind speed.

Emergency response and mitigation strategy by Firefighters for toxic gas release.
When receiving an emergency call in the event of a release of toxic gas, the fire team must report to the emergency site in accordance with fire department procedures.
While taking emergency turnout from the fire station, make sure of the wind direction, be in constant contact with the fire control room. After reaching the emergency site, the fire tender / fire engines should only be parked in the upwind / crosswind direction. The fire tender must be parked in a safe place and directed towards the exit.
Evaluate the scenario, get all the information about emergency situation from plant shift in charge or site incident controller, finalize the mitigation strategy and then instruct to all firefighters.
Immediately start the rescue operation and the search for the casualties. Ask all staff to leave the area and only allow key members with self-contained breathing apparatus at the emergency site.
All members of the fire crew must wear self-contained breathing apparatus (SCBA). Two firefighters must ensure the connection of the hydrant to the fire tender for make-up water and be ready for firefighting.
After consultation with the shift in charge of operations, the fire team must operate the water spray system, the ground monitors in water spray mode to dilute and disperse the gas / vapor. A water curtain must be provided to contain the released gas. The area within 200 meters should be monitored for LEL / ppm of toxic gas and continue to apply the water spray through the groundwater monitor. Ensure continuous application of water spray to the leak and the surrounding area for dilution. Call additional fire turnout and additional resources, if necessary.
Provide backup support to the maintenance team to arrest leaks, if necessary.
Ensure adequate drainage of spills and take the necessary measures to eliminate any contaminated surface.

4. Spillage of Hydrocarbon without fire emergency in Delayed Coker Unit (DCU)
Leak / spill may occur in the below process equipment and adjoining piping.
Fractionator column and other Columns, Stripper & Absorber, FG Scrubber & LPG amine contactor column, Debutanizer, Fractionator overhead receiver, Inter stage & Recontact drum, Debut overhead receiver drum, Rich amine and Stripper surge drum.

Emergency actions by Fire service responders/ fire department
When receiving the oil leak emergency call, follow the procedure explained in the above scenarios.
Discuss the mitigation strategy with the site incident controller for the application of water / foam to the affected process equipment to avoid thermal stress on the hot equipment / pipeline.
Fire-fighting foam can be used on spilled oil to prevent ignition and evaporation of the oil. Medium expansion foam is more effective as it can spread quickly to cover the maximum spilled oil surface. But the throw range is limited, if there is an approach problem, a low expansion foam can be applied. Foam should be applied gently to avoid agitation in spill. The foam jet can be targeted on the available surface of equipment or structure to form a uniform layer on the surface of the spill.
Do not disturb the foam layer, try to isolate the source of the leak by closing or closing the isolation valves. Make sure there should be no sources of ignition.
Use a sand or oil containment ramp/boom to contain the spill and prevent entry into the stormwater channel. Remove unwanted personnel from the emergency site and assist the maintenance team to stop the leak.
The spill can be rinsed off with water in the AOC. Wastewater treatment plant informed for the preparation necessary for the additional feed.
Constantly monitor the LEL / toxic gas with the operating team in consultation with the site incident controller. Ensure adequate drainage of spills and take the necessary measures to eliminate any contaminated surface.

5. Fire in Coker drum at Delayed Coker Unit
Emergency response and firefighting strategy for Fire department
Upon receiving the emergency call, follow the same procedure as mentioned in the above cases until you reach the emergency site.
Since the firefighting of the Coker drum is difficult due to its height, approach problems and extreme parameters such as high temperature and pressure, instruct the fire crew to use a fire entry suit, fire proximity suit, fire heat resistant suit, SCBA and other specialized equipment, if required.
The fire crew must assist the operations and maintenance crew in mitigating the fires and in shutting down the plant safely. Dry chemical powder must be used in coordination with the operation in-charge to avoid thermal shock to the equipment.
Maintain a safe distance from equipment to protect emergency responders from explosion. The fire chief must consult the site incident controller for any outside assistance such as mutual aid, auxiliary team, etc.
A riser system and a water spray system should be used to cool nearby equipment to protect it from radiation heat. A groundwater monitor and high volume long range monitors in water spray mode should be used to lower the temperature of the fire. The source of the leak must be isolated, otherwise the fire cannot be successfully extinguished. Steam lancers should be used in the event of a leak from very hot equipment.
After the fire has been extinguished, the steam lancers must be used continuously at the source of the leak until the situation has normalized. Keep the fire tender with fire crew on stand-by duty till all clear and for further completion of maintenance work.

6. Delayed Coker Unit - Fire in Heater (Furnace) scenario
Emergency response and mitigation actions by Firefighters
When you receive the emergency call, follow the same procedure as mentioned in the above cases until you reach the emergency site.
If the tube is punctured / burst, apply dry chemical powder (DCP) through the inspection window, avoiding contact with the counter current/ back draft.
In the event of a fire in the burners, use DCP for extinction and foam on the oil accumulated under the burners.
Ensure the application of steam to avoid the formation of a flammable mixture and use a continuous water spray system to cool nearby structures. Care should be taken to prevent water from entering the heater.
Assess the situation and ask the fire team to use a heat resistant suit with SCBA set and other specialized equipment. Operators must cutdown the fuel supply and increase the air supply for diluting and cooling the furnace.

7 Fire in Electrical equipment of Delayed Coker Unit
Emergency response plan for Fire department
When you receive the emergency call, follow the same procedure as mentioned in the above cases until you reach the emergency site.
Must guarantee all basic PPE and special PPE, including electric rubber gloves and SCBAs, as there may be a risk of electric shock and exposure to soot.
Make sure the power is off, if necessary, the burning cable can be cut and removed using a fire man axe and the person should wear rubber boots and rubber gloves.
If the equipment is inside the confined space, mechanical ventilation should be continued to eliminate the smoke. Apply dry substrates such as CO2 or DCP to fight fires.
Do not use fire-fighting water and foam in an electrical fire scenario. After confirming the positive isolation of the power supply, water can be used if there is no problem of damage to the electrical equipment. But always keep in mind, although someone has confined that the power is isolated, do not believe and avoid the application of water.

Approach route consideration in pre fire plan
When developing the pre-fire plan, consideration should be given to including an approach road. It can be marked on the layout diagram and can always be available in each fire vehicle.
Different colors must be used when marking the approach route, one for the main approach rout and the other for an alternative approach rout.

Layout of Fire Protection System in pre fire plan
The layout of the fire protection system must be marked in the drawing of the main layout of the plant. Different colours can be used for marking hydrants, fire water monitors, HVLRM, fire detectors, Manual call points and first arid firefighting system viz fire extinguishers and hose reels.
A copy of this layout must be available in each fire tender and with fire shift in charge in fire station.

Conclusion

The Delayed Coker Unit is extremely prone to major accidents, including fires, toxic releases and explosions due to its severe process conditions. Preparation of Pre fire plan or Pre incident plan for specific equipment in specific operational area is the key for efficient mitigation of any emergencies. Quantitative Risk assessment must be referred while preparing the pre fire plan. Effective emergency response can be assured by regular practicing i.e. conducting fire drill based on pre-fire plan. Practical firefighting strategies must be included in pre fire plan for all emergencies, including fires, explosions and the release of toxic gases. Important topics such as Delayed Coker Unit process description, list of hazards substances with their properties, list of available fire protection system, layout, approach rout marking on layout, line of action and fire fighting strategies, etc must be the part of pre fire plan.



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