Research On Modeling And Optimization Of Heavy-residue Gasification In An Entrained Flow Shell Gasifier

Shell entrained-flow,heavy-residue gasification technology is widely used in the petrochemical industries because of its low energy consumption,strong adaptability and high effective gas yield.However,there still exist some problems such as a delay time in concentration measuring and a short life of temperature sensors in the complicated conditions.As a result,it is difficult to realize the safer,more stable and optimal operation of the gasifier.Fortunately,the real-time simulation is an effective technology for unmeasurable variables so the dynamic mathematical model of the gasifier is established.The main contribution of this work is summarized as follows:Firstly,the gasifier is divided into the pyrolysis zone and the gasification zone according to previous research results.To simplify the model of the gasifier,the reactor is treated as a virtual reactor with a continuous stirred tank reactor(CSTR)and plug flow reactor(PFR)on the basis of the result of computational fluid dynamics(CFD).In order to compare the simulation results of the proposed model,a traditional model of CSTR in series is used as a basic model to describe the gasifier.In the dynamic model,the kinetics,mass balance,energy balance,and momentum balance are considered.To solve the proposed model,the partial differential equations are discretized by the orthogonal collocation method and they are transformed into ordinary differential equations.Secondly,the size of the gasifier and input data are taken from the industrial date.The simulation results of the integrated model of CSTR with PFR are compared with industrial date to valid the proposed model.In addition,the simulation results of the proposed model are compared with that of the model of CSTR in series.Thirdly,the influences of the ratios of oxygen/oil and steam/oil on the product and temperature distribution in gasifier are investigated.According to the simulation results of different ratios of oxygen/oil and steam/oil,the optimal operation parameters can be obtained.Finally,the conclusions are drawn in the end.The steady-state and dynamic-state simulation results are shown that the proposed model is better than the traditional model of CSTR in series.The computational performance of the proposed model is more superior than that of the traditional model of CSTR in series.