The vacuum produced by claw type oil-free vacuum pump is clean and pollution-free, and the solvent lost due to vacuum in concentration operation can be recovered. Therefore, the purpose of vacuum cleaning, energy saving and emission reduction can be achieved by using this pump. In this paper, claw type oil-free vacuum pump is used to replace roots water ring vacuum unit in concentration operation. The vacuum obtained has remarkable energy-saving and environmental protection effect, and the investment recovery period is short, which can create considerable economic benefits for enterprises.
In the concentration operation, a fine chemical industry mainly produces carboxylate. In the original process, roots water ring vacuum unit was used to obtain vacuum. The vacuum degree of roots water ring unit mainly depends on the vacuum degree of the front stage pump. The water ring pump of the front stage pump mainly relies on water as the working medium. During the working process, the energy consumption is very large, and the vacuum degree is unstable. At the same time, it also causes a lot of sewage and environmental protection pressure is very large Waste a lot of solvent.
After the transformation of the project, claw type dry vacuum pump is used for vacuum acquisition equipment. As claw type dry vacuum pump is a positive displacement pump, it mainly works by variable volume compression, and there is no lubricating medium in the working cavity. All parts contacting with the medium are clean. Therefore, what medium is extracted during the working process, what medium is discharged. Therefore, for the solvent with recovery value, dry-type vacuum pump is the best choice The recovery rate of solvent can be more than 98% by adding an air pump with a spiral wound condenser. After the transformation of the project, remarkable benefits are created for users, which are mainly reflected in three aspects: first, dry vacuum pump sewage treatment solves the environmental protection pressure; second, the solvent wasted by roots water ring unit can be recovered to about 98% after using dry vacuum pump; third, compared with roots water ring unit, the energy consumption (water and electricity) of dry vacuum pump is significantly reduced 。
2、 Energy consumption analysis of vacuum unit in concentration operation before and after equipment change
1. Brief description of process flow: during concentration operation, under the action of vacuum, the distilled n-hexane is cooled by the condenser and received in the n-hexane receiving tank. The solvent extracted by vacuum enters roots water ring vacuum unit, and is discharged with water from the water ring vacuum pump to the environmental protection sewage treatment unit for treatment. The performance parameters of roots water ring vacuum unit are as follows:
Pumping rate (L / s): 600
Limit vacuum pressure (PA): 40
Rated power (kw): 21.5
2. Brief description of process flow: when vacuum produced by claw type oil-free vacuum pump is used for decompression and concentration, the lost solvent which is not condensed before the pump and is evacuated by vacuum enters claw vacuum pump, and the gas is recovered again after cooling by condenser. The performance parameters of claw type oil-free vacuum pump are as follows:
Pumping rate (L / s): 150
Limit vacuum pressure (PA): 40
Rated power (kw): 15
Compared with roots water ring unit, dry-type vacuum pump has high vacuum degree. A single pump can replace the vacuum degree of roots water ring unit. At the same time, it can greatly reduce the operation cost in terms of power consumption. The water ring pump works by water and consumes a lot of water every day. The dry vacuum pump is energy-saving and environmentally friendly. While the water ring pump generates a large amount of sewage treatment, it also wastes a lot of organic solvents. The dry vacuum pump can solve the problem Under the pressure of environmental protection, remarkable economic benefits are created for users in the secondary recovery of solvent.