| In the batch production process of fine chemical industry,the process of reducing pressure is an extremely key link.Based on the production process of batch reactor in a fine chemical company,a multi-stage balanced step-down control strategy is proposed for the“BLEVE” accident that may happen in the process of reducing pressure,which can solve the problem that the sudden drop of pressure causes the liquid material to overheat and the BLEVE.The mechanism of the occurrence of bumps is studied.By the study for the mechanism of overheat limit and overpressure reduction limit,the relationship between the overpressure and overheat limit is analyzed,and the control method of judging the occurrence of explosion by the degree of pressure reduction is adopted to prevent the occurrence of the BLEVE.The initial temperature(pressure)and the step-down rate may affect the boiling delay time and the overheating temperature by the boiling delay,the multi-stage balanced step-down control strategy is proposed for solving the problem of BLEVE caused by imbalance in the reactor.Two processes by which the liquid reaches the boiling state are analyzed,the overpressure reduction limit and overpressure reduction degree are calculated according to the overheat limit caused by BLEVE,the modeling sample is obtained,and The least square method is used for fitting the Overdepressurization model,which can control the reactor and prevent the BLEVE occurrence,the model error is 10%.According to the multi-stage equilibrium buck control strategy of the batch reactor,the software and hardware implementation of the reactor buck control system is completed.The PLC control program is written by using Step-7,and the automatic production system with S7-300 PLC controller as the core and TIA Portal as the operation interface is established,and the multi-stage balanced buck control of the batch reactor is realized,Siemens PLCSIM simulator is used for simulating and proving the feasibility of the program. |
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