Batch type bulk technique polypropylene unit flashing kettle nitrogen replacement process

Abstract

The invention relates to a nitrogen replacement process for replacing propylene monomer in batch type bulk technique polypropylene unit by nitrogen, including continuous nitrogen replacement process or alternate evacuation nitrogen replacement process. Propylene gas produced in flashing kettle replacement process can be all drained into a gas holder to be recycled, propylene loss and nitrogen consumption are reduced, thus being beneficial to protection of atmospheric environment and safe production, and replacement efficiency is higher.

Description

technical field [0001] The invention relates to a nitrogen replacement process for replacing propylene monomer in a flash tank with nitrogen in a batch-type bulk polypropylene device. Background technique [0002] The batch bulk polypropylene process is a polypropylene production process independently developed and widely used in China. In the production process of the batch-type bulk polypropylene plant, under the action of catalysts and activators, liquid propylene undergoes polymerization reaction in the polymerization tank under the reaction pressure of 3.6MPa (absolute) and the reaction temperature of 75°C to form solid polypropylene. Acrylic powder. After the polymerization reaction, the remaining propylene in the polymerization tank needs to be recovered to obtain solid polypropylene powder without propylene. Under normal circumstances, the high-pressure recovery of propylene is carried out first, which is to rely on the pressure of the polymerization tank itself to...

AI Technical Summary

Problems solved by technology

The first is the waste of propylene resources. In the process of venting and replacing, a considerable amount of propylene in the exhaust gas of the flash tank is discharged into the atmosphere, resulting in the loss of propylene accounting for about 1-2% of the entire polypropylene process; the second is the waste of nitrogen. , each time the flash tank is pressurized and discharged with nitrogen, the amount of nitrogen consumed is roughly equivalent to the product of the volume of the flash tank and the pressure difference before and after discharge, which has become the main factor for the relatively high nitrogen consumption in the batch bulk polypropylene process; Furthermore, low-concentration propylene gas is directly discharged into the atmosphere, which pollutes the atmosphere and poses hidden dangers to safe production; in addition, due to the relatively large number of pressurization and discharge times, the replacement process is time-consuming.

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