Study On Benefit Evaluation Of Oxygen Generation Scheme For Underground Coal Gasification Project

Whether it is industrial oxygen or domestic oxygen,its demand is increasing year by year.In underground coal gasification projects,oxygen is a very important gasification agent.At present,the commonly used oxygen production methods in industry include cryogenic method,pressure swing adsorption method,membrane separation method and oxygen production by liquid oxygen vaporization.These oxygen production schemes have their own characteristics in terms of scale,operation,investment,and energy consumption.At present,scholars consider the single index in the evaluation of the benefits of the oxygen production program,and simply take the factor of cost as the criterion.For a complex system with multiple inputs and outputs such as the oxygen production program,various indicators should be combined.,To evaluate its benefits.In addition,cryogenic oxygen production and liquid oxygen vaporization oxygen production will release a large amount of cold energy during the oxygen production process.The use of cold energy can be considered in the benefit evaluation process,so as to ensure that the enterprise obtains the maximum benefit.Therefore,in this paper,the cold energy released in the process of cryogenic oxygen production and liquid oxygen vaporization is used for the production of liquefied natural gas(LNG)in underground coal gasification projects.The DEA method is introduced into the benefit evaluation of the oxygen-making program,and combined with the characteristics of the oxygen-making program,a benefit evaluation index system for the oxygen-making program is constructed.In the process of constructing the index system,considering both the utilization and non-utilization of cold energy,factor analysis was used to refine and summarize the comprehensive evaluation index system.In the context of the basic DEA model and factor analysis,referring to the idea of cross efficiency,the traditional model is improved,and a cross efficiency DEA model considering factor constraints is constructed to solve the large difference of traditional model indicators,poor discrimination of decision-making units,and weighting Dependence on issues such as greater.According to the evaluation results of the model,the benefits of the oxygen production plan of the underground coal gasification project are evaluated,and suggestions are provided for the benefit evaluation of the oxygen production plan.This paper takes the GZ underground coal gasification project as a research example,considers two scales of 5000m~3/h and 10000m~3/h of oxygen production schemes,and compares and analyzes the evaluation results of considering cold energy utilization and not considering cold energy utilization models.The results show that among the oxygen production schemes that do not consider cold energy utilization,cryogenic oxygen production has the best efficiency,pressure swing adsorption is the second,liquid oxygen vaporization is the third,and membrane separation is poor.Among the oxygen production schemes considering the utilization of cold energy,liquid oxygen vaporization is the most beneficial,followed by cryogenic oxygen production,pressure swing adsorption oxygen production third,and membrane separation oxygen production is poor.Under the two scales of 5000m~3/h and 10000m~3/h,the oxygen production method under the scale of 5000m~3/h is more effective.The evaluation results also show that after applying factor analysis to extract indicators,the cross-efficiency DEA model constructed in consideration of factor constraints can further evaluate and distinguish the oxygen production schemes,and provide basis and new ideas for the benefit evaluation of the oxygen production schemes of underground coal gasification.