Inner Fouling Analysis And Improvement Of PSHE In The Reforming Unit

The plate and shell heat exchanger, a relatively new heat exchanger, usually uses corrugated board sheet as heat transfer element. It is used to recover the heat of reaction products from reforming unit. But distributors and plate’s channels often black up because of salt deposition, coking, scaling, and filtering system failure. The problems reduce heat transfer efficiency. Thus this paper analyzes the mechanisms of salt deposition, coking and scaling. Meanwhile, a new type of distributor(T-distributor) is proposed. In-depth study is carried out between two types of distributor by numerical simulation method. The main contents of this paper can be listed as follows.(1) Bsaing on the heat exchanger’s dirt field analysis, it analyzes the formation mechanism of salt deposition in the PSHE of continuous reforming unit heat exchanger. Results show that the effluent of hydrogenation reaction system includes NH4Cl and NH4HS which crystallize easily. It is the root cause of the ammonia salt crystal deposition and corrosion. Besides, the crystalline trend of NH4Cl is significantly higher than NH4HS.(2) In the hydrocarbon process, the mechanism of carbon deposition on the surface of PSHE is analyzed, and thus to explain the phenomenon that the PSHE EA202 appeared coking after a period of operation.(3) Research is carried out to improve the filtration system and explore ways to clean up under different conditions. Numerical simulation method is used to study straight tube and T-tube distributor. The results showed that a straight tube distributor can achieve a good liquid arrangement at the inlet speed of 7m/s, while the corresponding speed for T-tube distributor is 9m/s. Compared to straight tube distributor, T-tube distributor has a smaller outlet pressure and a greater amount of material handing.This paper reveals the mechanism of salt deposition and coking of PSHE and improves the filter system. Besides, it studys the new type of distributor for PSHE and produces solutions and theoretical basis for industrial applications’ problems.