重整装置缠绕管式进出料换热器结焦结垢研究

RESEARCH ON COKING AND SCALING IN THE SPIRAL WOUND INLETAND OUTLET HEAT EXCHANGER OF REFORMING UNIT

通过试验研究和分析表征考察了催化重整装置缠绕管式进出料换热器不同部位结焦结垢样品的物理特性和组成结构,分析了引起换热器结焦结垢的主要原因。结果表明:下管箱和管程结焦结垢样品以烃类为主,壳程结焦结垢样品以催化剂粉尘为主,不同部位的结焦结垢样品均存在一定量的铵盐;下管箱结焦结垢的烃类以重油为主,管程和壳程结焦结垢的烃类重油组分含量相对较低,碳化程度较高;下管箱、管程、壳程结焦结垢样品的相对分子质量和芳烃环数依次增大,为了抑制缠绕管式换热器进料侧结焦结垢,应控制结焦结垢在下管箱的形成。缠绕管式换热器的清洗需采用机械除焦与化学清洗配合的方法,在清洗过程中应预防铵盐腐蚀。

The physical characteristics and composition of coking and scaling samples in different parts of the spiral wound inlet and outlet heat exchanger in catalytic reforming unit were investigated through experimental and analysis.Furthermore,the main causes of coking and scaling in the heat exchanger were analyzed.The results showed that the coking and scaling samples in the lower header and tube side were mainly composed of hydrocarbons,while the coking and scaling samples in the shell side were mainly composed of catalyst dust.There are certain amounts of ammonium salts in the coking and scaling samples in different parts.The hydrocarbons for coking and scaling in the lower header are mainly heavy oil,while the heavy oil content for coking and scaling in the tube side and shell side is relatively low and the degree of carbonization is high.The molecular weight and aromatic ring number of coking and scaling samples in the lower header,tube side and shell side increase sequentially.To inhibit coking and scaling in spiral wound inlet heat exchanger,the formation of coking and scaling in the lower header should be controlled.The cleaning of spiral wound inlet and outlet heat exchanger should adopt the combination method of mechanical coke removal and chemical cleaning,and ammonium salt corrosion should be prevented during the cleaning process.