Research On The Failureanalysis Of Plate Heat Exchanger

Plate heat exchanger as an important process equipment and energy-saving equipment in production and living, it has advantages of high efficiency of heat exchange, compact structure, small occupational area, more plate forms, assembling flexibility, comfortably for disassembly and cleaning, etc. So it is widely applied in petroleum, chemistry, light, food and refrigeration industry. However, failure accidents of plate heat exchanger such as leaking, scale blockage, stress corrosion cracking often occur in the process of designing, manufacturing and using because of various reasons. Therefore, in order to ensure the normal operation of the plate heat exchanger, extend the service life, identify the reasons for failure, reduce recurrence of various failure accidents, avoid unnecessary casualties and property losses caused by accidents, it is tangible and significant for us to conduct comprehensively failure analysis on plate heat exchanger.Based on the basic ideas of failure analysis and comprehensive fault tree analysis for plate heat exchanger, according to the failure sample of plate heat exchanger for a petrochemical plant in Guangdong, physics and chemistry detection analysis were done systematically, according to materials, environmental, and stress factors, analysis and discussion were made. So draw the following conclusions:(1)There are many type of failure and accident for plate heat exchanger, the influential factors for plate heat exchanger are even more, failure analysis should be make according to the material, design, manufacture, working condition, stress, management, etc. by using intuitive and levels of the accident tree analysis method that based on the comprehensive analysis and research of the failure of plate heat exchanger, found the main types and the firstly, secondary influential factors for failure.(2)The surface of failure plate heat exchanger was found pitting, at the same time,corrosion due to the side of cooling water, corrosion resulting in the rupture of the 304 austenitic stainless steel plate sealed tank, there are typically features for stress corrosion cracking at Macro-cracks and fracture, microstructure analysis results. High residual stress is exsiting in sealing groove. Stress corrosion cracking occurred when plate soak in the liquid with high intensity of Cl ?and S 2?.(3)Metallographic microstructure examination are normal and typical austenitic structure. Materials with higher levels of the chemical composition of the Si, but the Ni is slightly lower. High levels of Si will lead to cold brittle, Ni content is too low to reduce the resistance of corrosion for stainless steel. Materials hardening leading to increases the possibility of brittleness and more sensitive to stress corrosion.(4)In the actual production operation, the concentration of corrosive media in the fluid should be strictly control, chemical composition of standard conditions required for materials should be chosen reasonably, manufacturing process practices and the corresponding heat treatment should be conducted by rules, the design for key structures should be reliable, proper assembly and comprehensive management for equipment and so on, so as to prevent the plate heat exchanger from recurring failure.