Vacuum system of pumping steam

In the process of vacuum impregnation, vacuum drying and vacuum freeze-drying, the gas extracted from the vacuum system is mainly steam and other condensable steam, and the working vacuum degree is mostly 10 ~ 10-1pa. In foreign countries, roots pump and oil seal mechanical pump are usually used for air extraction. For this reason, in recent years, the maximum inlet pressure of water vapor is the index of foreign oil sealed mechanical pumps (usually 103 ~ 3 × 103pa), while the domestic oil sealed mechanical pumps generally do not have this index. Moreover, the check function of some mechanical pumps equipped with air ballast valve is not strong, and the gas ballast effect is not obvious, which can not achieve the purpose of large amount of steam pumping, resulting in a large amount of steam condensation in the pump oil, Oil and water mixed to form white emulsion, reducing the sealing and lubricating performance of mechanical pump. The corrosion liquid will cause rust inside the pump body, and the rusty iron powder will fall into the oil and become reddish brown, and circulate in the pump together with the pump oil, which will have adverse effects on the service life and limit vacuum degree of the pump.

(1) The steam jet pump is suitable for the vacuum system with large displacement, and the system needs to be equipped with working steam source.

(2) Oil booster pump + oil seal mechanical pump, the system is not suitable for the gas phase drying of transformer, especially in the oil booster pump, the naked electric furnace is strictly used, otherwise the open fire is easy to cause explosion accident.

(3) ZJ Roots pump + ZJ Roots pump + double stage water ring vacuum pump, the pumping system can obtain higher limit vacuum degree and larger displacement. However, the investment cost of the system is high, and it is easy for the working fluid of the water ring pump to flow back into the vacuum container, and the pumping efficiency of the water ring pump is low, and the unit power consumption is 50% higher than that of the slide valve pump. For example, various types of roots water ring vacuum unit.

(4) Slide valve pump + water ring pump or ZJ Roots pump + slide valve pump + water ring pump, because the slide valve pump is equipped with a front stage pump (water ring pump) in the system, so its compression ratio is reduced, so the water vapor is rarely condensed in the slide valve pump, but there is still a defect in Item 3.

(5) ZJ Roots pump + rotary vane vacuum pump is equipped with high-efficiency gas ballast valve, reliable oil-water separator and reasonable design of lubrication system, so that the system can operate continuously at the inlet steam pressure of 3000pa. This is an economical and reliable vacuum system for pumping steam abroad in recent years. For example, various types of rotary disc vacuum unit.

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