The problem of sticking cauldron in PVC large-scale polymerizer

The sticky caulking problem of polymerizers that has long troubled chlor-alkali enterprises has been successfully solved by Haohua Aerospace Chemical Co., Ltd. The reporter learned from the company's production and operation records on July 9 that 108 cubic meters of polymerizers have been changed from every 70 pots in the past to once every 500 pots, and the modified polymer cups can reduce the number of clean cups per year. Times. Based on this calculation, the company's five polymerization tanks can reduce the number of clean tanks 60 times a year, increasing the production of PVC by more than 14,000 tons per year, and at the same time reduce the cleanup cost by 600,000 yuan.

It is understood that chlor-alkali enterprises in the production of PVC, the polymerization reactor will appear different degrees of sticky cauldron problems. The viscous cauldron is the polymer that forms fouling on the inner wall of the polymerizer, resulting in a decrease in the heat transfer coefficient, difficulty in discharging during the stripping and drying process, and a decrease in the quality of the PVC resin due to mixing of wall scale into the material, which not only affects the self-control performance of the polymerizer, but also reduces productivity and equipment utilization. Rate, affect product quality, there are still large security risks. For a long time, chlor-alkali enterprises have been working hard to solve this problem, but have not made substantial progress.

In April 2011, Yonghua Aerospace chose a 108-millimeter polymerization tank for its annual output of 240,000 tons of ion-exchange membrane caustic soda and 200,000 tons of PVC resin. However, in the initial stage of production, the problem of sticky caulking is more serious. After a single cauldron is run for 70 to 80 times, it is necessary to clear the cauldron once. In order to solve this problem, Haohua Aerospace organized technical personnel to tackle the problem. After repeated trials and trials, it determined the technological transformation program of “optimizing the coating process and extending the production cycle”.

During the renovation process, technicians adjusted the gap of the shower baffle, reinforced the spray center tube support, and ensured the spraying effect. At the same time, the nitrogen discharge rate was adjusted, the heat exchange amount was stabilized, and the heat pipe was added to each nozzle of the kettle top to keep the liquid-free monomer. The inner wall of each nozzle was polished smooth, and the kettle liquid was manually brushed again before putting it into operation. On this basis, the operator will inspect irregularly the nozzles of the coating kettle, condenser water injection and flushing water to ensure that they are put into operation after inspection. With the joint efforts of engineers and technicians, the polymerization reactor has been once purged from 70 to 80 times in the past and gradually changed to 200-rejection. At present, it has reached the best score of 500 bottles or more.

It is reported that with the adjustment of the national industrial policy, chlor-alkali enterprises will preferentially choose 108 cubic meters of large-scale polymerizers when they are new to the project. Although it has the advantages of good resin quality, low energy consumption, and many types of PVC resin, due to the kettle type and stirring problems, the sticking kettle phenomenon is easy to occur. Among domestic companies that use this polymerizer, the worst one is every 60 to 70 reactors, the best one is every 100 to 150 reactors, and the clearer has a long time and high cost, which affects the capacity of the PVC plant.