Chemical process pump common problems and selection methods

Cooling Problems The delivery of high-temperature media places higher demands on the structure, materials and auxiliary systems of the pump. Below we discuss the cooling requirements for different temperature changes and the company's application of pumps:
1. For media temperature below 120 ℃, usually do not set a special cooling system, use more of their own media for lubrication and cooling. DFL (W) H chemical pump , DFL (W) PH shield chemical pump (class H should be used for shielded motor over 90 ℃); DFCZ common type and IH chemical pump can make the temperature Up to 140 ℃ ~ 160 ℃; IHF lined with fluorine pump up to a maximum temperature of 200 ℃; only CQB ordinary magnetic pump temperature does not exceed 100 ℃. It is worth mentioning that for the easy-to-crystallize or media containing particles should be equipped with a sealing surface flushing pipe (design have left interface).

2. For media above 120 ° C and within 300 ° C, a cooling chamber is normally to be provided on the pump cover and the seal chamber is also to be filled with coolant (to be fitted with a double-ended mechanical seal). When coolant is not allowed to penetrate the medium , It should be taken after the cooling medium itself access (through a simple heat exchanger). The company has DFCZ chemical process pump, GRG high temperature pipeline pump and HPK hot water circulation pump (under development) for selection, the other CQB-G high temperature magnetic pump can be used within 280 ℃ high temperature medium

3 for more than 300 ℃ high temperature medium, not only need to cool the pump head part, the suspension bearing chamber should also be equipped with cooling system, the pump structure is generally the central support form, the mechanical seal is best to use metal bellows type, but the price is high The price is more than 10 times the ordinary mechanical seal). There are currently DFAY centrifugal pump temperature can reach 420 ℃ (under development).

Sealing problems No leakage is the eternal pursuit of chemical equipment, it is this requirement contributed to the growing use of magnetic pumps and shielded pumps. However, there is still a long way to go without leakage, such as the life span of the magnetic pump isolation sleeve and shielding pump shielding sleeve, the material pitting problem, the reliability of static sealing, and the like. Now some of the basic aspects of sealing a brief introduction is as follows:

1. Sealing For the static seal, usually only two forms of seals and seals, and O-ring seal again the most widely used; for dynamic seals, chemical pumps rarely use packing seal, the main mechanical seal , Mechanical seal has a single end and double end, balanced and unbalanced type, balanced type for high pressure medium seal (usually refers to the pressure greater than 1.0MPa), double end machine seal is mainly used for high temperature, easy to crystallize, there is Viscosity, containing particles and toxic volatile medium, double-ended machine seal should be injected into the sealed chamber isolation fluid, the pressure is generally higher than the medium pressure 0.07 ~ 0.1MPa. 2. Sealing material Chemical pump static sealing materials generally use fluorine rubber, special circumstances only use PTFE material; mechanical seal ring static material configuration is more critical, not cemented carbide is the best on the cemented carbide, the price is high On the one hand, the difference between the two is not unreasonable, so it is best to distinguish between the characteristics of the media (Note: The American Petroleum Institute API610 Eighth Edition of the mechanical seal and piping systems typical configuration in Appendix D have more detailed provisions )

Viscosity Problem The viscosity of a medium has a significant effect on the performance of the pump. As the viscosity increases, the lift of the pump drops, the head and flow of the optimum conditions decrease, and the power rises, resulting in lower efficiency. General parameters on the sample are the performance of the transport of water, when the transport of viscous media should be converted (different viscosity correction factor can be found in the relevant conversion chart). For the viscosity of the pulp, paste and viscous liquid delivery, it is recommended to use screw pump.