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一催化裂化装置的设备出现氢鼓包和焊接裂纹,是由于原料油中的硫、氮化物在催化过程中生成的水、硫化氢,氨和氰化物造成的。腐蚀和氢渗透在 pH 值为7.8～8时最轻。pH 值降低时,氢渗透因酸腐蚀而增加;当 pH 值超过8.0时,氢渗透率则随二硫化物离子(HS~-)浓度的增加而增加。如果溶液中存在氰根离子(CN~-),则氢渗透更加迅速。铁被腐蚀的反应为:Fe°+2HS~-→FeS↓+S~(-2)+2H°(1)2H°→H_2↑(2)硫化铁(FeS)锈皮在 pH 为7～8
Hydrogen kits and welding cracks in the equipment of a catalytic cracking unit are caused by the water, hydrogen sulfide, ammonia, and cyanide generated from the sulfur and nitrides in the feedstock during the catalytic process. Corrosion and hydrogen permeation are the lightest at pH 7.8-8. Hydrogen permeation increases due to acid corrosion when the pH is decreased, and increases with the concentration of disulfide ions (HS ~ -) when pH exceeds 8.0. Hydrogen permeates more rapidly if cyanide ions (CN ~ -) are present in the solution. The reaction of iron corrosion is: Fe ° + 2HS ~ - → FeS ↓ + S ~ (-2) + 2H ° (1) 2H ° → H_2 ↑ (2) FeS rust scales at pH 7 ~