Sour Water Treatment

Sour water, rich in NH3 and H2S content, is produced from refinery crude distillation units, hydrocracker, hydrodesulfurization units, gas handling, amine regenerators, delayed cokers, sulfur plant tail gas treating units, and the like. Sour water is produced by the steam stripping operation during crude distillation hydrotreating and hydrocracking operations. During most hydrocracking and hydrotreating operations, NH3 and H2S

Water Treatment Plant Steam Stripping

blower p10' bl-102

Figure 9-8. Sewage treatment blower p10' bl-102

Figure 9-8. Sewage treatment system.

Table 9-9

Sanitary Sewage Treatment (Aeration Unit) Operating Conditions and Stream Quality

TREATED

PARAMETERS UNITS INFLUENT EFFLUENT

Table 9-9

Sanitary Sewage Treatment (Aeration Unit) Operating Conditions and Stream Quality

FLOW RATE/UNIT

gpd

60,000

SUSPENDED SOLIDS

ppm

<500

30

BOD

ppm

300

30

COD

ppm

1000

30

TOTAL OIL

ppm

150

0

TOTAL NITROGEN AS NH3

ppm

80

0

pH

6.5-7.5

6.5-8.0

TEMPERATURE

°F

90-95

90-95

DETENTION TIME

hr

22

vol/lb BOD

ft3

48.5

AIR SUPPLIED, lb/BOD REMOVED

SCF

105

RESIDUAL OXYGEN

ppm

2

>2

CHLORINE RESIDUAL

ppm

0.5-1.0

are formed in the reactors due to elimination of sulfur and nitrogen in the feed. These two react to form solid ammonium sulfide salts. Ammoniacal condensate injection is required in the reactor effluent ahead of HP separation to prevent deposit of solid ammonium sulfide salts in pipes. Deposit is prevented by dissolving most of the ammonia and approximately an equal quantity of H2S in water, followed by removing the resulting aqueous solution from the system in the form of sour water. Also in hydrotreating plants, steam stripping of desulfurized liquid streams, to remove H2S, produces sour condensate containing dissolved H2S.

Sour water coming from various refinery units has a very high concentration of H2S and NH3, typical values being 10,000-20,000 and 5000-10,000 ppmw, respectively. This water also contains some suspended and dissolved hydrocarbons. The composition of sour water from a distillate hydrocracker unit is shown in Table 9-10. Typically a 200MBPD refinery of medium complexity may produce lOOOgpm sour water. After removing NH3, H2S, and small amount of oil, this water can be reused.

Table 9-10 Sour Water Composition

sour water,

nh3,

h2s,

oil,

source

gpm

ppmw

ppmw

ppmw

HP DRUM (2585 psig)

80.4

12750

20400

_

LP DRUM (500 psig)

8.1

6800

25500

10

STRIPPER OVERHEAD DRUM

30.3

850

3400

5

TOTAL

118.8

BASIS 44,000 BPSD HYDROCRACKER UNIT. FEED SULFUR = 2.6 WT%, NITROGEN 695ppmw.

NOTES:

BASIS 44,000 BPSD HYDROCRACKER UNIT. FEED SULFUR = 2.6 WT%, NITROGEN 695ppmw.

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  • stefan
    Is NH3 column required in sour water stripping unit?
    6 years ago

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