Comprehensive Optimization Of Refinery Hydrogen Network For Coupling Hydrogen Production Unit

With the continuous adjustment of petrochemical industry structure and the stricter environmental regulations,hydrocracking units and hydrotreating units are widely used in refineries to adjust product structure and improve product quality.The cost of hydrogen has become the second largest raw material cost for refineries after the cost of crude oil.Therefore,it is of great significance for refinery to reduce hydrogen production cost and improve hydrogen resource utilization.Among them,the cost of hydrogen in refinery mainly comes from the hydrogen production by steam reforming unit.Based on the previous research,this paper studied include three aspects:multi-objective optimization of hydrogen production operation parameters,feedstocks network optimization of hydrogen production unit and matching optimization of refinery hydrogen network of coupling hydrogen production unit.The main work content is as follows:The process simulation method was used to model the hydrogen production by steam reforming unit.Also,the relationship between the steam to carbon ratio and the conversion reaction temperature on the hydrogen production,the cost of hydrogen production unit,and the NO_x emission were calculated and analyzed.A multi-objective optimization method considering the economic and environmental indexes of hydrogen production unit was established.The multivariate function model of MATLAB regression was used.The normalization method is applied to construct the objective function between economy and NO_x emissions.The calculation result shows that the multi-objective optimization depends to a large extent on the selection of economic weights.When=0.5,the optimal operating conditions reaction temperature is 857.7℃,the steam to carbon ratio is 2.76,and the NOx emissions is decreased by 24.76%,with the economic cost increased by only 0.64%.Aiming at the problem of how to screen various types of refinery dry gas as hydrogen feedstocks,the raw material of hydrogen production unit was optimized systematically.Based on Process simulation model of hydrogen production unit,the effects of hydrogen-to-carbon ratio,inert component and olefin components on the economic performance of hydrogen production units were analyzed.The results show that feedstocks with high hydrogen-to-carbon ratio,low inert component content,and low olefin content are more economical.Economic indicators for measuring the profit of hydrogen production from different types of raw materials are proposed.Moreover,the LP mathematical model of raw material optimization for hydrogen production plant was established,and the method was applied to optimize the raw material for hydrogen production of a petrochemical plant,so as to save the operating cost of hydrogen production of 10.342 million yuan/year.Aiming at the limitation that the hydrogen production unit is only a hydrogen utility in the current hydrogen network optimization.Based on the process simulation model of hydrogen production unit,the linear relationship between the hydrogen purity at the inlet of hydrogen production unit and the energy consumption and hydrogen production was derived.An optimal nonlinear mathematical model of refinery hydrogen network considering hydrogen production plant is established.This model allows the hydrogen stream of various purity in the hydrogen network system to be recycled to the inlet of the hydrogen production unit to reduce the total cost of the system.The calculation shows that the total cost of hydrogen network is reduced by2.12%compared with the traditional model.