Study of variables that affect the corrosion of sour water strippers

Conference · Thu Jan 01 04:00:00 EST 1976 · Proc., Am. Pet. Inst., Sect. 3; (United States)

OSTI ID:7318438

Berry, W E; White, E L; Boyd, W K

A laboratory study has been conducted under API sponsorship of the variables that affect the corrosion of sour water strippers. Variables included NH/sub 3/ concentrations, NH/sub 3/-H/sub 2/S ratios, KCN concentrations, temperature, and oxygen (air) in the system. Most of the experimental work was conducted in glass equipment at ambient pressures with steel and stainless steel (Type 304) being the alloys of interest. Corrosion rates were obtained from linear polarization measurements and coupon weight loss data. Hydrogen probes were included in the system to determine periods of active corrosion. Free sulfur, cyanide ion, thiocyanate ion, ferrocyanide ion, and pH were monitored by periodic sampling during test. The results of the study revealed that steel corroded at high rates in NH/sub 3/-H/sub 2/S solutions containing 1 to 10% NH/sub 3/ if cyanide ion was present. The function of the cyanide was to destroy the relatively protective sulfide film that forms on steel in these systems. The product of the cyanide-FeS reaction appeared to be soluble ferrocyanide ions although evidence for Fe(SCN)/sub 3/ was found in several tests. The corrosion rate of steel in NH/sub 3/-H/sub 2/S-KCN appeared to be greater at high NH/sub 3/ concentrations. The accelerated corrosion of steel appeared to be associated with NH/sub 4/HS in the NH/sub 3/-H/sub 2/S-KCN system. Oxygen reduced the rate of attack on steel in the NH/sub 3/-H/sub 2/S-KCN system apparently by the formation of polysulfides; however, the oxygen was most effectivein retarding corrosion if introduced before a large reservoir of cyanide has built up in the system. Preliminary runs in autoclaves with 4% NH/sub 3/ + H/sub 2/S + KCN at 50 psig indicated that steel corroded more rapidly under the pressurized conditions. Type 304 stainless steel did not corrode under conditions that caused accelerated attack on steel, but could be activated to corrode at high rates by cathodic charging to destroy its normally protective film.

• Research Organization: Battelle-Columbus Labs., OH
• OSTI ID: 7318438
• Conference Information: Journal Name: Proc., Am. Pet. Inst., Sect. 3; (United States) Journal Volume: 55
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
36 MATERIALS SCIENCE
360105 -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION
CORROSION RESISTANT ALLOYS
CORROSIVE EFFECTS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HYDROGEN COMPOUNDS
HYDROGEN SULFIDES
IRON ALLOYS
IRON BASE ALLOYS
MANAGEMENT
MATERIALS
NICKEL ALLOYS
PETROLEUM REFINERIES
PROCESSING
REMOVAL
STAINLESS STEEL-304
STAINLESS STEELS
STEELS
SULFIDES
SULFUR COMPOUNDS
WASTE MANAGEMENT
WASTE PROCESSING
WATER REMOVAL