Emergency are divided into two parts:

Universal Type• Power Failure• Steam Failure• Cooling Water Failure• Instrument Air Failure• Feed Failure• Furnace Coil Failure• DCS Failure• Unit fire

Here we will be discussing about Universal type.

Unit Specific• Tempered water failure• DM Water/ BFW failure• Failure of OWS/CRWS system• Failure of CBD system• Critical Exchangers tube leaks• Failure of Pressurized FO pump

to seals• Desalter emergencies• APH failure

Action from the panel:•Close stripping stream to all stripper, Atm. and Vacuum column.

•Ensure safety shut down switches are in run position.

•Close Furnaces fuel gas and oil control valves manually.

•Ensure all MOV at pump suction and discharge are closed.

•Hold pressure in the crude column and stabilizer by manually operating 11-PIC-1506 and 11-PIC-1101 respectively.

•Hold levels in columns, vessels by manually closing the respective control valves.

•Close 12-PV-1218 on non-condensable return line to inlet of first stage ejectors.

• Shut off ejectors steam and close hot well vent valve and hot well gases to 11-FF-00-101.

Action from the field:

•Ensure furnace snap shut valves on gas and oil lines are shut. Close block valves on oil and gas.

•Ensure coil steam snap shut control valves on FF-00-101,102 have opened wide and block valves of individual coils are open.

•Close individual adco valves of oil and gas burners of FF-00-101,102.

•Close main block valve on water injection line.

•Shut stripping steam to stripper and Column.

•Block off desalter water drains and block valves at water injection points.

•Purge individual oil lines by opening purging steam to the oil guns and furnace by snuffing steam.

• Close pump discharge valves.

• Reduce feed to stabilizer and the hot oil to stabiliser reboiler.

• Establish fuel oil circulation in the heater circuit. Open purging steam to individual oil burners.

• Open emergency steam to all the eight passes of the vacuum heater 12-FF-00-101.

• Open fuel gas to inlet of first stage ejectors to bring up the system pressure to 0.5 kg/cm2g.

• As soon as power is available, flush the system with flushing oil

Cooling water failure will result in a high pressure of column and temperatures and sometimes even the relief valve will pop. If it for short duration or partial reduce throughput. Still the pressure is not control the unit is shutdown as per procedure.

All fire to the heater including pilot will be cut off. Burner guns will be steam purged.Other pumps can be run to empty out and cool the system as far as possible.

Stop stripping steam to crude column and strippers. Crude column refluxing should continue at a flow rate to cool down the column.

If cooling water supply is not restored soon and flushing oil from offsite is available at sufficient pressure, RCO can be flushed out through VR circuit. Alternatively, steam purging can be done to displace the heater stuff.

In Vac. Section cut off steam to ejectors and close UV-1402 on vent gas KOD routing gases to Atmospheric heater and vent line valve UV-1401.

Atm. Section:• Ensure that safety shut down control valve UV-1451 & UV-1452 cuts off fuel gas supply and

UV-1453 cut off fuel oil supply to the heater. Isolate individual oil burners.

Vacuum Section:• Ensure safety shut down valve UV-1151 & UV-1152 cuts off fuel gas supply and UV-1153 cut

off fuel oil supply to heater.

Common:• Burner guns will be steam purged. FD/ID fans will be allowed to run as long as possible.

Reduce the through put slowly to minimum and if instrument air failure is for longer duration start the normal shutdown of the unit.

• The flow through shut-down valves and control valves open on air failure will be manually restricted to maintain normal level, pressure and temperature in columns and vessels.

• In the event of failure of a control valve it can either be bypassed or operated with the aid of a hand wheel provided. All bypass valves are globe type to facilitate control of flow rate.

Atm. Section:• Steam for atomising and stripping will no be available. Reduce throughtput slowly and Cut off

fire to the heater. FD/ID fans may be kept running.

• Shut off all burners and flush out all oil burners.Keep fuel oil circulation on.

• Resort to circulation in the bottom section using VR Circuit and crude tank. Vacuum unit will be on short circulation through its furnace.

• Start close circulation by diverting 11-PA-CF-110 A/B discharge to 12-FF-00-101 inlet through VR circuit and crude tank.

• Stop all other pumps.

• Hold levels and pressures by taking all controls on manual.

Vacuum Section:• Steam for atomising, ejector and stripping will no be available. Reduce throughtput slowly and

Cut off fire to the heater. FD/ID fans may be kept running.Shut off all burners and flush out all oil burners.

• Close ejector steam valves, UV-1402 on vent gas KOD gases line to crude heater fire box and vent line valve UV-1401.

• Close non-condensable return to inlet of first stage ejectors through PIC-1218. Back in fuel gas and maintain pressure at about 0.5 kg/cm2g.

• Start circulation from 12-PA-CF-105 A/B to 12-FF-00-101 inlet. Keep the coil flow at minimum level. Start emptying out heavy stocks to slop by diverting a part of 12-PA-CF-105 A/B discharge through VR circuit.

• Pump out products to slop.

• Cut in flushing oil to the bottom of vacuum column. Start close circulation by diverting 11-PA-CF-110 A/B discharge to 12-FF-00-101 inlet through VR circuit and crude tank.

UPS FAILURE Causes:1) DCS failure - (operator station becomes blank)2) PLC failure3) Communication system failure

Failure of DCS will cause various control valves to go to fail safe position. There will be no indication of pressure temperature level and flow in the panel as well as in the back up panel. PLC also fails. So plant automatically takes emergency shutdown. As an additional precautionary measure release emergency trip switch from CCR and also put all trip switched in ‘RUN’ position.Telephone also can be used for communication.

Action to be taken in the filed:Isolated all heaters. Put off all motors except air fin fans and reflux pumps. Put off them after

watching the column pressure locally. Watch pressure and level locally and take corrective action. Isolate all yield b/vs.

If operator station alone fails back up panel will be live. All the control valves will keep the same status. If it is only for a short period shutdown need not be taken. Otherwise emergency shutdown of the plant is to be taken. In this case PLC and communication system will not fail.

UPS FAILURE Causes:1) DCS failure - (operator station becomes blank)2) PLC failure3) Communication system failure

Failure of DCS will cause various control valves to go to fail safe position. There will be no indication of pressure temperature level and flow in the panel as well as in the back up panel. PLC also fails. So plant automatically takes emergency shutdown. As an additional precautionary measure release emergency trip switch from CCR and also put all trip switched in ‘RUN’ position.Telephone also can be used for communication.

Action to be taken in the filed:Isolated all heaters. Put off all motors except air fin fans and reflux pumps. Put off them after

watching the column pressure locally. Watch pressure and level locally and take corrective action. Isolate all yield b/vs.

If operator station alone fails back up panel will be live. All the control valves will keep the same status. If it is only for a short period shutdown need not be taken. Otherwise emergency shutdown of the plant is to be taken. In this case PLC and communication system will not fail.

• Inform the situation to the field operators and concerned people.

• Release emergency push button-on the console.

• Ensure that Furnaces fire is cut off.

• Shut all the stripping steam b/vs in field.

• Stop all the pumps, reflux and circulating reflux after the level is minimum.

• Watch column pressure in filed and control.

• Take emergency shutdown as per procedure.

• Inform the situation to the field operators and concerned people.

• Release emergency push button-on the console.

• Ensure that Furnaces fire is cut off.

• Shut all the stripping steam b/vs in field.

• Stop all the pumps, reflux and circulating reflux after the level is minimum.

• Watch column pressure in filed and control.

• Take emergency shutdown as per procedure.

Atm. Section:• In Case of low feed activation of low- low flow switches FALL-1401 B to

1408 B which will cut off fuel oil and fuel gas to heater.

• Failure of crude supply to unit may occur due to improper functioning of offsites Crude pump to Unit, Crude booster pump. If crude pump discharge pressure tends to come down cut down unit throughput to restore normal pressure.

• Standby pumps will be pressed into service for any trouble with the running pump.

• If feed supply cannot be resorted immediately the unit will be brought to hot circulation by diverting 11-PA-CF-110 A/B/C discharge to furnace inlet through VR line. Temperature will be maintained around 200 oC. Products will be stopped. Water to coolers will be throttled.

Vacuum Section:• Feed Failure will be indicated by FAL-1101 A to 1108 A in 12-FF-00-101.

• FALL-1101 B to 1108 B which will cut off supply of fuel oil and fuel gas to the furnace. If the failure is due to atm. column bottom pump, start the spare pump.

• Cut firing rate in the furnace in case FALL is not activated already.

• Put the unit on circulation by diverting 12-PA-CF-105 A/B discharge to furnace inlet through start up line.

• Bring down the unit as per normal procedure.

Atm. Section:• All fire in the heater will be cut off. Stop ID/FD fans.

• Feed to the heater will be stopped and Stuffing steam will be opened in radiation and convection sections.

• Emergency coil steam will be opened in all the passes of the heater.Product/pump around pumps will be stopped when they loose suction.

• Top refluxing will be continued as long as possible. Stripping steam to crude column and stripper will be stopped.

• Column pressure will be closely watched for any rise of pressure due to additional amount of steam put into the heater coil.

• RCO circuit will be flushed by taking flushing oil from offsite.

Vacuum Section: In addition to first three point in the atm. section

• Cut off ejector steam and close cooling water to ejector condensers and drain water from them. Vacuum should be broken with steam to avoid air entry through ruptured tube.

• Float the unit on fuel gas and allow gas to escape to furnace by sufficiently increasing steam to heater coils. Empty out the tower by pumping from all trays and column bottom till pumps loose suction.

• Take flushing oil into the column and dilute its content, pump out the oil from the column. Drain out remaining oil from the column to CBD.

• Steam out the unit as per normal procedure and hand over to maintenance for installing blinds as per master blind list.

Thanks