The Fccu Gas Concentration Unit

The FCCU main fractionator column overhead receiver V-112 operates at about 20psig and 104°F (see Figure 4-4). The vapors from this

COMPRESSOR WET GAS INTERSTAGE HIGH PRESSURE PRIMARY SPONGE KO DRUM

SUCTION DRUM COMPRESSOR SUCTION DRUM RECEIVER ABSORBER ABSORBER V-123

GAS TO HaS REMOVAL PLANT

GAS TO HaS REMOVAL PLANT

Compressor Suction Drum Size

MAIN

COLUMN FCCU

OVERHEAD

VAPOR

MAIN

COLUMN FCCU

OVERHEAD

VAPOR

DEBUTAN1ZER NET

OVERHEAD LIQUID

(LPS)

CIRCULATING LCO

TO AND FROM

A

Figure 4-4. FCCU gas concentration unit. KO = knockout; C.W. = cooling water; LCO = light cycle oil.

drum are compressed in wet gas compressor P-120 to 205 psig. A part of the vapor condenses by compression and is collected in high-pressure receiver V-122.

The vapor from the high pressure receiver is fed to the bottom of primary absorber C-122, a column with 40 plates and operating at about 200 psig. The liquid separated in overhead drum V-112 of main FCCU column is used as the absorbent medium. The rich effluent containing the absorbed gas flows to high pressure receiver V-122.

The unabsorbed gases from C-122 flow to a second absorber C-123, the sponge absorber, a column with 20 plates and operating at 197 psig. The bottom stream from the sponge absorber goes back as reflux to the main FCCU fractionator column.

The liquid from high-pressure receiver V-122 goes to stripper C-124, with 35 plates, to strip off light ends. The stripper bottoms next go to debutanizer column C-125 with 40 plates, operating at 160 psig. Here, any LPG contained in the feed is separated as an overhead product, and the light gasoline stream is recovered as the bottom stream from the debutanizer column.

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  • crystal
    What does a wet gas compressor do in a fccu?
    7 years ago

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