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MY 634 HDS PST > Reaction Subsystem- Major Equipment, How it works, Controlling, & Shut Down > Flashcards

Reaction Subsystem- Major Equipment, How it works, Controlling, & Shut Down Flashcards

1
Q

What are the 3 subsystems of the 634 HDS?

A

Reaction Subsystem, Stipper Subsystem, Hydrogen Compression Subsystem

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2
Q

Overall, what happens in the Reaction Subsystem?

A

undesirable sulfure and nitrogen compounds in the feed stream are converted to hydrogen sulfide and ammonia. Olefins and aromatics in the feed are saturated with hydrogen.

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3
Q

Why are the feed filters important?

A

They remove solids from the feed stream which could foul the catalyst beds in the reactor.

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4
Q

What does an increasing differential pressure across the in-service filter indicate?

A

The filter media is plugging and must be replaced. If the differential pressure is excessive, the stand-by filter is placed in service and the in-service filter is taken out of service

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5
Q

The natural gas blanket on the Feed Surge Drum Prevents _________ from entering the drum and provides sufficient suction pressure for the Reactor Fresh Feed Pumps.

A

Oxygen

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6
Q

The Target Outlet temperature for the Reactor Feed heater (F1) is ________ F

A

665 F

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7
Q

What is the normal control mode for the Feed Surge Drum pressure (pc0001)?

A

Local

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8
Q

What can happen if the fresh feed flow (as indicated by FT0003 A/B/C) drops below 1070 BPH?

A

Low- Low (2oo3 voting) The SIS interlock is activated which initiates a shutdown of the Reactor feed heater.

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9
Q

The potential effects of a low combined hydrogen flow to the fresh feed (FI0016) are ________ ______ and insufficient hydrogen for desired ______, resulting in off-spec product.

A

catalyst deactivation, reactions

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10
Q

The potential effects of a high reactor outlet temperature are premature _________ of the catalyst and loss of _________ of the recycle hydrogen stream.

A

deactivation, purity

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11
Q

What is the high pressure alarm setpoint on the unit pressure controller (PC0007) _________ -psig?

A

907 psig

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12
Q

A low hot flash drum level can allow high-pressure gas to flow to the Product Stripper resulting in damage to the tower’s _________ and the possibility of lifting PSVs.

A

tray’s

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13
Q

The potential effect of a high Hot Flash Vapor Air Coolers outlet temperature is a decrease in the __________ of the recycle Hydrogen

A

purity

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14
Q

The Reactor Feed Heater high coil pressure alarm activates at _________-psig.

A

980 psig

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15
Q

The SIS will trip the Reactor Feed Heater on a low-low fuel gas pressure of _______

A

2%

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16
Q

What happens if the SIS detects a low current of 20 amps to the Forced Draft Fan motor?

A

After a 30 decond delay, the SIS interlock is activated to switch the heater to natural draft.

17
Q

What are the process variables on the Reactor Feed Heater that are equipped with triple redundant instrumentation.

A

Feed flow (FT3A/B/C), Hydrogen flow (FT16A/B/C), Fuel gas pressure (PT5134A/B/C), Furnace pressure (PT5131A/B/C)

18
Q

If the SIS initiates a trip of the heater due to a high or low furnace pressure, the heater is switched to _________ ________ mode prior to the actual trip.

A

natural draft

19
Q

What action does teh DCS take if the SIS trips the Reactor Feed Heater due to either Low Feed flow or Low Hydrogen Flow?

A

The DCS will automatically override the signal from termperature controller TC1 and place teh fuel gas pressure controller (PC5134) in manual with a minimum fire output of 10% to prevent coking of the heater tubes.

20
Q

If the SIS automatically switches the Reactor Feed Heater from Balanced draft to Natural Draft, what actions must occur to prevent an eventual complete trip of the heater?

A

Within 30 seconds of trip to natural draft, both transmitters on the stack damper and forced draft air door much show >50% open to avoid an SIS trip of the heater. After 30 minutes, one transmitter on each damper must indicate >30% open to avoid a heater trip.

21
Q

What are the three circumstances under which the Reactor Feed Heater SIS can be bypassed?

A

Startup, Maintenance, and Emergency

22
Q

The ___________ use fiber filter elements to remove particulates from the gas oil. The filtered feed exits to the feed surge drum

A

Feed Filters 634 D1001/D0006B

23
Q

The ____________ is a holding tank for feed to the unit. It provides surge capacity to operate for 30 mins without receiving feed. It also serves as a reservoir to provide steady feed flow to the reactor fresh feed pumps.

A

Feed Surge Drum 634D0001

24
Q

The ____________ is an electric motor-drivin pump. The _____________ is a turbine driven pump that uses 550-psig steam to drive teh turbine. Medium pressure steam (125-psig) exhausts from the turbine. The pumps increase the pressure of the feed stream to 730-psig. The increased pressure allows the feed stream to join the combined hydrogen stream

A

Reactor fresh feed pumps 634P0001

25
Q

The _____________ use Hot Flash Drum vapor flowing through the exchanger tubes to preheat the fresh feed flowing on the shell side.

A

Hot Flash Vapor/Fresh Feed Exchangers 634E0053A-D

26
Q

The ____________ uses Hot Flash Drum Vapor flowing through the exchanger tubes to heat the combined hydrogen gas stream flowing on the shell side. The heated hydrogen mixes with the heated feed before teh combined feed stream enters the reactor feed/product stripper bottoms exchangers.

A

Hot Flash Vapor/Hydrogen Gas Exchanger 634E0054

27
Q

The _______________ use product stipper bottoms flowing on the shell side to heat the reactor feed flowing through the exchanger tubes before the feed enters the reactor feed/reactor effluent exchanger.

A

Reactor Feed/ Product Stripper Bottoms Exchangers 634E0051 A/B

28
Q

the _______________uses reactor effluent on the tube side to heat the reactor feed before it enters the reactor feed heater.

A

reactor feed/reactor effluent exchanger 634 E0052

29
Q

The _______________ is a refinery fuel gas-fired heater that raises the temperature of the feed before it enters the reactor. The reactor feed heater is a balanced-draft heater equipped with an air preheater for energy conservation.

A

Reactor feed heater 634F0001

30
Q

The___________ is a centrifugal fan that provides high velocity ambient air to the reactor feed heater as combustion air, which improves air/fuel mixing for the small burners in the heater

A

Forced draft fan 634N0011

31
Q

The ______________ is equipped with a rotating drum charged with ceramic elements that transfers heat from the hot heater flue gas to the ambient air from the Forced Draft Fan prior to the air entering the reactor feed heater.

A

Air preheater 634E0001

32
Q

The _____________ is a centrifugal fan taht draws the hot flue gas out of the reactor feed heater convection section and through the air preheater. The fan then discharges the flue gas back into the heater stack from which it is vented to the atmosphere.

A

Induced Draft Fan 634N0001

33
Q

The _________ utilizes two beds of catalyst to treat the unit feed. The catalyst used in the reactor is Nickel Moly catalyst and cobalt moly. In the reactor, the sulfur and nitrogen compounds in the heated feed are saturated with hydrogen and converted by an exothermic reaction to hydrogen sulfide (H2S) and Ammonia (NH3). Hydrogen gas is used as quench for temperature control between the two beds.

A

HDS Reactor 634R0001

34
Q

The ____________ separates the cooled reactor effluent stream into a hydrocarbon liquid stream and vapor stream. Hydrocarbon liquid is released from the bottom of the vessel to the product stripper in the Stripping Subsystem. The vapor exits the top of the drum and is cooled in the hot flash vapor/fresh feed exchangers and the hot flash vapor/hydrogen gas exchanger.

A

Hot Flash Drum 634D0002

35
Q

The ____________ inject high-pressure wash water into the hot flash vapor stream as it leaves the hot flash vapor/hydrogen gas exchanger. The water injection removes ammonia and ammonia salts from the proces stream.

A

Condensate Water Injection Pumps (Wash Water Pumps) 634P0013 A/B/C (Also supply 633 and 635 HDS units)

36
Q

The _______________ are two banks of air coolers that cool the hot flash drum vapor by heat exchange with ambient air.

A

Hot Flash Vapor Air Coolers 634E0001A/B

37
Q

The ____________ separates the cooled stream from the Hot Flash Vapor Air Coolers into hydrocarbon liquid, sour water, and vapor streams. The Hydrocarbon liquid stream is released to the product stripper in the stripping subsystem and the sour water exits the bottom of the drum to the sour water stripper in SRC. The vapor flows from the top of the drum to the recycle Gas Contactor in the Hydrogen compression subsystem.

A

Cold Flash Drum 634D0003

MY 634 HDS PST (6 decks)

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