Roots screw dry vacuum system for chemical distillation

Recently, chemical enterprises producing pharmaceutical and pesticide intermediates such as ethyl chloroacetoacetate have officially replaced the original two-stage Roots+water ring vacuum system with the dry vacuum system combined with Roots+screw vacuum pump to solve the problem of unstable vacuum performance in the process of product distillation.

The original vacuum system of the enterprise consists of a water ring vacuum pump as the front pump and a two-stage Roots vacuum pump. The vacuum required for the operation of the product distillation process is about 50 Pa or less. But the vacuum unit is affected by temperature in actual operation, and the vacuum performance of the former water ring vacuum pump is unstable, which often causes the Roots vacuum pump to run at high load due to the excessive pressure difference between the outlet pressure and the inlet pressure. The rotor heats heavily and expands, and the gap becomes smaller. In addition, the incomplete condensation of the inlet air of the main pump makes it easy for the pumped medium to condense and coke in the Roots vacuum pump, which leads to the formation of the vacuum pump. The vacuum pump jammed.

Water ring vacuum pump has the advantages of simplicity and isothermal compression, but its vacuum performance is limited by the temperature of its working fluid. The limit vacuum degree can not be lower than the saturated vapor pressure of the working fluid at that temperature. Generally, water at 20 C is used as working fluid at room temperature. The saturated vapor pressure is about 2338 Pa. When the saturated vapor pressure rises to 7380 Pa around 40 C, the pumping limit vacuum capacity of vacuum pump changes and decreases accordingly (the increase of the inlet pressure of water ring vacuum pump means that the exhaust pressure of Roots vacuum pump also rises). It is precisely because of this instability, coupled with the conventional Roots vacuum pump can not adapt to long-term work under high pressure difference, so the enterprise water ring vacuum system in the operation process is prone to the problems mentioned above.

As a dry vacuum pump, screw vacuum pump has no oil, water and other media involved in the main process, and its vacuum performance is not affected by external temperature. In the distillation application of the enterprise, the screw vacuum pump as the front pump can achieve a higher vacuum degree and maintain a large pumping speed, which not only provides a stable and good prerequisite for the operation of Roots vacuum pump, but also reduces the configuration series of Roots vacuum pump, which can be achieved by adjusting the original two-stage Roots+water ring to one-stage Roots+screw. Vacuum conditions required for enterprise process application reduce the possibility of equipment failure and operation cost.

In addition, the use of Roots + screw dry vacuum system not only eliminates the problem of unstable vacuum performance, but also brings additional benefits – reducing water consumption and eliminating later sewage treatment problems.

Roots-screw dry vacuum system for chemical rectification

JZJA(P)LG Screw Pump System

System model Pump model Suction speed Ultimatevacuum Inlet diam Outlet diam Motor power
L/s Pa mm mm Kw
JZJA(P)LG150-3 ZJ(P)150 / LG50 150 1×10-1 100 40 3 / 5.5
JZJA(P)LG150-2 ZJ(P)150 / LG70 150 100 40 3 / 7.5
JZJA(P)LG300-6 ZJ(P)300 / LG50 300 150 40 4 / 5.5
JZJA(P)LG300-4 ZJ(P)300 / LG70 300 150 40 4 / 7.5
JZJA(P)LG300-2 ZJ(P)300 / LG150 300 150 65 4 / 15
JZJA(P)LG600-8 ZJ(P)600 / LG70 600 200 40 7.5 / 7.5
JZJA(P)LG600-4 ZJ(P)600 / LG150 600 200 65 7.5 / 15
JZJA(P)LG600-3 ZJ(P)600 / LG200 600 200 65 7.5 / 22
JZJA(P)LG1200-6 ZJ(P)1200 / LG200 1200 250 65 11 / 22
JZJA(P)LG150-21 ZJ(P)150 ZJ(P)70 LG50 150 2×10-2 100 40 3 1.5 5.5
JZJA(P)LG300-41 ZJ(P)300 ZJ(P)70 LG50 300 150 40 4 1.5 5.5
JZJA(P)LG300-22 ZJ(P)300 ZJ(P)150 LG70 300 150 40 4 3 7.5
JZJA(P)LG600-43 ZJ(P)600 ZJ(P)150 LG50 600 200 40 7.5 3 5.5
JZJA(P)LG600-42 ZJ(P)600 ZJ(P)150 LG70 600 200 40 7.5 3 7.5
JZJA(P)LG1200-44 ZJ(P)1200 ZJ(P)300 LG70 1200 250 40 11 4 7.5
JZJA(P)LG1200-42 ZJ(P)1200 ZJ(P)300 LG150 1200 250 65 11 4 15
JZJA(P)LG2500-43 ZJ(P)2500 ZJ(P)600 LG200 2500 320 65 22 7.5 22

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