Vapor Recovery Section

The vapors from the fractionator overhead drum flow to the compressor suction drum and then to two-stage coker gas compressor C-151 (see Figure 6-2). The first stage discharge flows through the compressor

COMPRESSOR SUCTION DRUM V 151

COMPRESSOR COMPRESSOR

3NTERSTAGE INTERSTAGE

CONDENSER DRUM

E-151 V-152

SPOhlGE TAIL GAS OEBUTANIZGR DEBUTANIZER

ABSORBER SEPEARflTOR V-167 OV£FHEAO

V-156 V-156 CONDENSER

COKER OVERHEAD LIQUID FROM FRACT 10N ATOR DRUM

VAPORS FROM FflACTlONATOR OVERHEAD DRUM

OVERHEAD COOLER COMPRESS' SUCTION PUMP

SOUR WATER JM5I FROM

F RACTION ATOR OVERHEAD DRUM

VAPORS FROM FflACTlONATOR OVERHEAD DRUM

Trim Condenser

LIGHT COKER NAPHTHA

HEAVY COKER NAPHTHA

Figure 6-2. Delayed coker (vapor recovery section). C.W. = cooling water.

LIGHT COKER NAPHTHA

HEAVY COKER NAPHTHA

Figure 6-2. Delayed coker (vapor recovery section). C.W. = cooling water.

interstage condenser to the compressor interstage drum. Sour water from absorber stripper feed drum V-153 is injected into the compressor firststage discharge to prevent cyanide-induced corrosion in the downstream equipment. Vapors from the compressor interstage drum enter the second stage of the compressor.

Liquid hydrocarbon from the interstage drum is pumped to absorber stripper feed condenser E-152, and sour water flows to the coker fraction-ator overhead cooler. Vapor from the second stage of the compressor is combined with the following: overhead vapor from the stripper, sour water from fractionator overhead drum, and hydrocarbon liquid from compressor interstage drum.

The combined flow is cooled in absorber stripper feed trim condenser E-152. The cooled vapor/liquid mixture from trim cooler E-153 flows to absorber stripper feed drum V-153. The hydrocarbon liquid from the feed drum is pumped by stripper feed pump to the absorber stripper. Sour water from the absorber stripper feed drum flows to the compressor inter stage condenser.

In the stripper, light hydrocarbons are stripped out. The liquid from the bottom of the absorber stripper flows through debutanizer feed bottom exchanger E-161 to debutanizer V-157. Stripper overhead vapors return to absorber stripper feed condenser E-152. The stripper is reboiled with a steam reboiler. Sour water withdrawn from the stripper enters a water separator (not shown in Figure 6-2) then to the battery limit.

Vapor from the absorber stripper feed drum flows to the bottom of the absorber. This vapor is contacted in countercurrent flow with the lean oil. This lean oil consists of unstabilized gasoline from the fractionator overhead drum and a stream of cooled naphtha from the bottom of the debutanizer V-157. Rich oil from the bottom of the absorber flows to absorber stripper feed trim condenser E-153.

The vapor from the top of the absorber flows to the bottom of sponge absorber V-155, where it is contacted in counercurrent flow with cool lean sponge oil. The sponge absorber minimizes the loss of naphtha to the fuel gas. The tail gas from the top of the sponge absorber flows to tail gas separator V-156, where entrained liquids are removed before flowing to battery limits. Rich sponge oil from the bottom of the sponge absorber is sent to the coke fractionator.

Debutanizer V-157 splits the liquid from the stripper into two streams, a C3/C4 overhead and a naphtha bottom stream. The debutanizer is reboiled using heavy coker gas oil (HCGO) pumparound from the fractionator.

Naphtha from the bottom of the debutanizer is cooled as it passes through the debutanizer feed/bottom exchanger and absorber stripper reboiler. The net naphtha product flows under level control to splitter V-159. A stream of cooled naphtha is recycled by the lean oil pump to the absorber for use as lean oil. The overhead vapor from debutanizer is condensed in debutanizer overhead condenser E-162 and enters debutanizer overhead drum V-158. Any uncondensable vapor from the overhead drum is vented to the compressor suction drum. Hydrocarbon liquid from the debutanizer overhead drum flows to the debutanizer overhead pump, which handles both the debutanizer reflux and the C3/C4 product stream.

Naphtha splitter V-159 separates the net naphtha product from the debutanizer into a light coker naphtha and heavy coker naphtha product. The naphtha splitter is reboiled with HCGO pumparound. The naphtha splitter overhead vapor is condensed in the splitter overhead condenser and collected in the splitter overhead drum. The splitter overhead pump pumps both the splitter reflux and the light coker naphtha stream. The heavy coker naphtha from the bottom of the naphtha splitter is pumped through the splitter bottom product cooler to the battery limits by the splitter bottom product pump.

The light hydrocarbon vapor from the blowdown settling drum are sent to the fuel gas recovery system.

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  • luwam robel
    How naptha absorbs lighter hydrocarbons in sponge oil absorber?
    8 years ago
  • J
    WHAT FOR IS THE VAPOR RECOVERY SECTION?
    3 years ago

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