Investigation of dynamic behavior of acetylene production by oxidative pyrolysis of natural gas

Abstract

Modern chemical-engineering systems, as a rule, are characterized by the complexity of chemical technology processes, the behavior in a context of the information uncertainty and deficiency as well as a vast number of internal and external factors exercising unpredictable influence on the entire system operation. Therefore, it is particularly important that chemical industries should solve the problem of defining valid states in order to ensure the process safety in various situations arising in a technological cycle. At the same time, the main task of effective diagnostics and process safety of chemical-engineering systems is the timely detections of malfunctions that can cause extraordinary situations, with the aim of their preventing and avoiding. In the paper the authors propose a technological model of acetylene production by oxidative pyrolysis of natural gas. The process operation uncertainty is stipulated by the feed composition variability (natural gas, oxygen), the temperature dependence of chemical kinetic constants, the equipment behavior during the operation (‘coking up’), etc. The mathematical model includes the material and heat balance equations calculated for the oxidative pyrolysis reactor processes (mixing of the original components, oxidative pyrolysis, ‘quenching’ of oxidative pyrolysis products). The Matlab Simulink-based model allows us to plot graphs of transient processes in a reactor and to evaluate the effect of various factors on the acetylene content in the pyrolysis gas at the reactor outlet. The model adequacy is validated by statistical data obtained at the existing acetylene enterprise. The model can be used to evaluate indeterminate forms on the basis of finite-difference approximation for the purpose of defining different states of a system, as well as to design the oxidative pyrolysis process control system.