Maintenance of cryogenic air separation equipment

Temperature difference is the power of heat transfer. As long as there is temperature difference between two materials, they will carry out the heat or cold transfer spontaneously. The heat is always transferred from the fluid with higher temperature to the lower temperature fluid. Although the heat transfer process of various heat exchangers is not identical, the heat transfer law is basically the same. The following is an example of the most widely used dividing wall heat exchanger: heat is transferred from hot fluid to cold fluid through the wall and flows in the opposite direction. The whole heat transfer process is divided into three stages. In the first stage, convection heat transfer: the heat flow body transmits heat to the wall surface. This process not only has heat transfer caused by the relative displacement of each part of the fluid, but also has heat conduction in the fluid, which is the comprehensive function of convection and heat conduction. In the second

According to the dye composition of penetrant, it can be divided into fluorescent penetrant testing, dye penetrant testing and fluorescent dye penetrant testing, which are represented by I, II and Ш respectively. According to the penetrant removal method, it can be divided into water washing type penetrant testing, lipophilic post emulsifying penetrant testing, solvent removing penetrant testing and hydrophilic post emulsifying penetrant testing, which are represented by A, B, C and D respectively; according to the type of imaging agent, it is divided into dry type Powder imaging agent, water soluble imaging agent, water suspension imaging agent, solvent suspension imaging agent and self imaging were expressed as a, b, c, d, e, respectively. II Cd means solvent removal dye penetrant testing, and the imaging agent is solvent suspension type.