TFE裂解工艺F22汽化节点非稳态本质安全分析

Unsteady State Inherent Safety Analysis of F22 Vaporization Node of TFE Pyrolysis Process

在化工过程中,过程安全分析是非常重要的。然而,在非稳态条件下,过程工艺参数处于变化状态,并且缺乏系统性的本质安全分析方法,更容易产生危险和事故。作者对二氟一氯甲烷(F22)水蒸气稀释裂解中F22汽化非稳态过程进行了本质安全性分析。首先,利用热量动态平衡方程,对F22汽化过程建立了集总参数数学模型,并对模型进行数值计算,得到与实际相吻合的F22汽化操作温度、操作压力以及F22出口气体流量的非稳态时间过程曲线。然后,系统地分析了影响四氟乙烯(TFE)生产过程本质安全的因素,从物质、工艺和设备3个方面建立TFE生产过程本质安全指标体系,并根据相关标准与文献将指标分级并建立隶属函数。将选取的相应指标值和计算所得数据输入MATLAB模糊逻辑工具箱,利用IF-THEN规则建立模糊推理规则,用面积重心法逆模糊化求得各指标的本质安全度。分别运用层次分析法和变权思想的方法计算得出各指标的初始权重和变权权重。最后,计算得出F22汽化非稳态过程的系统本质安全度。结果表明:F22汽化过程达到稳态的时间将近1 000 s,前500 s温度、压力及出口气体量升高迅速,稳态值分别为268.55 K、432.405 kPa和1.085 kg/s;初始时本质安全度0.576 4下降至稳态时的0.574 2,显示该过程在非稳态(如启动)阶段表现出稍高的风险。这种方法和计算结果为该工艺中F22汽化节点相关的安全设计、建设、监控和管理提供参考理论依据。

Process safety analysis is important and necessary in the chemical process industries.However,a lack of a systemic methodology for inherent safety studies in an unsteady state,which causes more hazards and accidents.In order to analyze the inherent safety of the F22 vaporization unsteady state process of the steam dilution pyrolysis,the lumped parameter mathematic model for the F22 vaporization was established by using the thermal equilibrium equation.The model was numerically calculated to obtain the unsteady state time course profiles of operating temperature,pressure and F22 gas outlet mass flow rate,which were consistent with the field data.Then,the factors influencing the inherent safety of the TFE production process were systematically analyzed.The inherent safety index system of the TFE production process was established from three aspects of chemical,process,and equipment.The indices were graded according to relevant standards,and literature and membership functions were established.Index values and calculated data were input into the MATLAB Fuzzy logic toolbox.The IF-THEN rules were used to establish the Fuzzy inference rules,and the inherent safety degree of each index was defuzzified by the method of center of area (COA).The initial weight and variable weight of each index were calculated using the combination of analytic hierarchy process and variable weight method.Finally,the inherent safety degree of the F22 vaporization node was calculated.The results showed that the steady state time is nearly 1 000 s.The temperature,pressure,and outlet gas volume in the first 500 s increase rapidly.The steady state values are 268.55 K、432.405 kPa and 1.085 kg/s respectively.The inherent safety degree decreases with time.The initially inherent safety 0.576 4 dropped to 0.574 2 at steady state.The results showed that the unsteady state (a start-up process) appears a higher risk. The method and results provide a theoretical basis for the safe design,monitoring, and management of the F22 vaporization node in the process。