Evaluation And Comparative Study Of SIL In Nitrification In Tubular And Tank Reactors

In the pharmaceutical and chemical industry,high-risk chemical processes such as nitrification and diazotization in tubular and kettle reactors are often involved.In order to ensure the smooth and safe operation of hazardous chemical processes,a careful evaluation of the safety instrumented system?SIS?of high-risk chemical processes in tubular and kettle reactors is necessary.However,at present,the safety integrity level?SIL?assessment of SIS in China is not very mature in terms of SIL rating and SIL verification,which leads to the inability of the SIS to accurately meet the needs of the project.Little research has been done on the process for comparison of SIL assessments.Based on this situation,this paper improves the traditional SIL evaluation method,proposes a new SIL evaluation method,and conducts research based on two nitration processes of o-methylbenzoic acid in the tubular and kettle reactors.The main contents of this article are as follows:?1?Thermal safety experiments were performed on the nitration process of o-methylbenzoic acid,and the four parameters T_p?T_D24?MTSR and MTT of the thermal safety assessment were obtained.A process risk assessment was performed to compare the safety of the two processes in terms of process hazards.?2?Based on the comparative analysis of the advantages and disadvantages of various SIL assessment methods for safety instrument systems at home and abroad,and the improvement of traditional SIL assessment methods,this paper proposes a method that can accurately calculate the frequency of accidents and the severity of accident consequences.SIL evaluation method.This method analyzes the causes of hazards in detail,accurately determines the causes to each valve,pump,or process parameter,etc.,accurately calculates the frequency of accidents,and proposes some suggestions and measures to prevent danger by calculating the critical importance of each cause.The occurrence of an accident;at the same time,the DI index value in the I2SI assessment method is used to quantify the severity of the accident.?3?Using traditional HAZOP+LOPA analysis of the SIL rating method and the newly proposed SIL rating method to carry out the dangerous and operable process of the nitrification process in o-methylbenzoic acid in the tubular reactor and the kettle reactor Performance analysis,safety instrument function SIL rating and SIL verification;at the same time calculate the DI index value of the two processes.The SIL level and DI index value of the two processes are compared and analyzed.Based on the process thermal safety assessment,SIL assessment,and accident severity calculations for the two processes of o-methylbenzoic acid nitration in tubular and kettle reactors,the adiabatic temperature of the tubular reactor process is obtained in terms of process thermal safety.When the temperature rises to 12.52°C,the risk of reaction runaway is level 1,and the process risk level is 2.The adiabatic temperature rise of the kettle reactor process is 119.62°C,the reaction runaway risk is level 2,and the process risk is level 5.In terms of SIL evaluation results,the evaluation results of the HAZOP+LOPA analysis method in the tank reactor are two SIL1 and two SIL2.The new proposed method evaluation results are high in liquid level SIL1,and the remaining three are SIL2;in the tube type The evaluation result of the HAZOP+LOPA analysis method in the reactor is a SIL2 level,and the newly proposed method is evaluated as a SIL2 level and a SIL1 level.In terms of the severity of the accident consequences,the nitrification DI value in the kettle reactor is 67.0671,and the tubular reaction The nitrification DI value in the device was 5.4940.The comparative analysis of the three indexes shows that the safety of the o-methylbenzoic acid nitration reaction process is higher in the tubular reactor.The research in this paper has certain guiding significance for the popularization and application of the tubular reactor technology in the nitration reaction process in the future.