甲醛废热锅炉复合钝化处理的研究

对用表面复合钝化处理的20g碳钢代替1Cr18Ni9Ti不锈钢制造生产甲醛的氧化反应器(废热锅炉)进行了研究,结果表明,用铝酸盐和磷酸盐等对碳钢表面进行复合钝化处理,形成含Mo、P的复合钝化膜,使碳钢具有良好的耐蚀性.经此复合钝化处理的碳锅可用来代替不锈钢,制造甲醛氧化反应器废热锅炉。此废热锅炉已在湘潭合成化工厂得到实际应用,其使用寿命已超过该厂原不锈钢废热锅炉的寿命.

ON THE PASSIVATION SURFACE TREATMENT FOR FORMALDEHYDE OXIDATION REACTORS BY USING A COMPOUND PASSIVANT

In order to search for a new substitution for the stainless stell 1Cr18Ni9Tiused in formaldehyde(CH_2O)oxidation reactor(i.e waste heat boiler),a practical techno-logy of passivation surface treatment has been explored for 20g carbon steel by using acompound passivant containing molybdate and phosphate.The aim of the passivation treatmentis to form a uniform passive film on the steel surface,acting as corrosion-prevention.Thephase constituents and microstructure of the passivation film were examined by means of X-raydiffraction (XRD) analysis and metallography observation.Its corrosion resistance wastested in CuSO_4 solution, NaCl solution, and formaldehyde vapor.Experimental results haveshown that the carbon steel coated with such passive film exhibits high corrosion resistancein formaldehyde production, and thus can substitute for the stainless steel used in the Oxida-tion reactors.Successful practical application has been found in Xiangtan Synthetic andChemical Plant.The service life of the oxidation reactors made of 209 carbon steel after thepassivation surface treatment has been over the average service life of the previous reactormade of the stainless steel.