Chemical pump use related issues

Cooling problem

The transportation of high-temperature medium puts higher requirements on the structure, materials and auxiliary system of the pump. Let's talk about the cooling requirements of different temperature changes and the company's applicable pump type:

1. For media with a temperature below 120 °C, there is usually no special cooling system, and the medium itself is used for lubrication and cooling. Such as IHG, ISWH chemical pump, PHG shielded chemical pump (protection level of shielded motor should exceed H grade when over 90 °C); and CZ common type and IH chemical pump can achieve upper temperature limit of 140 °C~160 due to suspension structure °C; IHF lining fluorine pump can be used up to 200 °C; only CQB ordinary magnetic pump can not exceed 100 °C. It is worth mentioning that the medium that is easy to crystallize or contains particles should be equipped with a sealing surface flushing line (designed with an interface).

2. For mediums above 120 °C and below 300 °C, a cooling chamber shall be provided on the pump cover. The sealing chamber shall also be connected to the coolant (with double mechanical seal), when the coolant is not allowed to penetrate into the medium. It should be taken after cooling its own medium (can be realized by simple heat exchanger). At present, the company has CZ type chemical process pump, GRG high temperature pipeline pump and LQRY hot water circulation pump (under development), and CQB-G high temperature type magnetic pump can be used for high temperature medium within 280 °C.

3. For high temperature medium above 300 °C, not only the pump head part needs to be cooled, but also the suspension bearing chamber should be equipped with a cooling system. The pump structure is generally in the form of a central support. The mechanical seal is preferably a metal bellows type, but the price is high ( The price is more than 10 times that of a normal machine seal). At present, the company only has a 2CY\LQRY centrifugal oil pump that can reach a temperature of 420 °C (under development).

Sealing problem

No leakage is the eternal pursuit of chemical equipment. It is this requirement that has led to the expansion of the application of magnetic pumps and shielded pumps. However, there is still a long way to go before there is no leakage, such as the life of the magnetic pump isolation sleeve and the shielded pump shield, the pitting problem of the material, the reliability of the static seal, and so on. Some basic information on sealing is briefly introduced as follows:

1. Sealing form For static sealing, there are usually only two forms of sealing gasket and sealing ring, and the sealing ring is the most widely used O-ring; for dynamic sealing, the chemical pump rarely uses packing sealing, mainly mechanical sealing. The mechanical seal has single-end and double-end, balanced and unbalanced types. The balanced type is suitable for high-pressure medium sealing (usually refers to pressure greater than 1.0MPa). Double-faced machine seal is mainly used for high temperature, easy crystallization, and For viscosity, particle-containing and toxic volatilized media, the double-faced machine seal should be filled with a spacer liquid into the sealed chamber. The pressure is generally higher than the medium pressure of 0.07~0.1MPa.

2. Sealing material The material of the chemical pump static sealing is generally made of fluororubber. In special cases, the PTFE material is used. The material arrangement of the mechanical seal static and dynamic ring is more important. It is not the hard alloy to the hard alloy, the price is high. On the one hand, it is not reasonable to have no hardness difference between the two, so it is best to treat them differently according to the characteristics of the medium.

(Note: The typical configuration of the American Petroleum Institute API 610 eighth edition for mechanical seals and piping systems is detailed in Appendix D)

Viscosity problem

The viscosity of the medium has a great influence on the performance of the pump. When the viscosity increases, the lift curve of the pump decreases, and the head and flow rate of the optimal working condition decrease, and the power increases, so the efficiency decreases. The parameters on the general sample are the performance when conveying clean water, and should be converted when conveying the viscous medium (the correction coefficient for different viscosities can be found in the relevant conversion chart). For the transportation of higher viscosity pulp, paste and viscous liquid, it is recommended to use screw pump. The company G single screw pump is suitable for medium viscosity up to 1000000cst.

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