Research On Simulation And Technical And Economic Evaluation Of Natural Gas Liquefaction Process In An LNG Plant

With the improvement of science and technology and living conditions,traditional fossil energy can hardly meet the demands of production and living.At the same time,the traditional fossil energy seriously pollutes the environment,which has become an important problem to be solved in the current environmental pollution.For sustainable development and environmental protection,new energy sources emerge at the historic moment.As a type of new energy,liquefied natural gas(LNG)has been rapidly developed and applied because of its characteristics such as cleanliness,high efficiency,high unit calorific value,reliable supply,low price and abundant resources.Although natural gas liquefaction technology is widely used in China at present,it still needs to be further developed and improved due to the blockade of foreign advanced technology.The natural gas liquefaction plants in China mostly use small and medium-sized equipment and adopt relatively mature mixed refrigerant liquefaction technology,but there are some inherent problems in technology and operation,and the research and development of mixed refrigerant liquefaction technology are not perfect yet.Therefore,it is necessary to establish a complete set of natural gas liquefaction process to solve the technical defects and problems in the actual application of the plant.In order to solve the problems existing in the process and improve the liquefied natural gas technology in China,this paper takes a 90*10~4Nm~3/d liquefied natural gas plant as the research object,analyzes the refrigeration principle of the current mainstream refrigeration process,and establishes the thermodynamic model of the mixed refrigeration liquefaction process by using the simulation software HYSYS.According to the scale of the plant and the actual operating parameters,the operation of the refrigeration process was analyzed,and the double-cycle mixed refrigerant natural gas liquefaction(DMR)process was simulated,and the process parameters were optimized.Finally,the construction and development of the plant were analyzed from the perspective of economic evaluation and project benefits.The main work is as follows:(1)Analysis and selection of refrigeration mode:Based on the analysis of the LNG process,the cascade liquefaction process and the liquefaction flow process with mixed refrigerant were decided to be adopted,and the basic principles and technological processes of the two liquefaction methods were summarized and analyzed.(2)Determination of LNG liquefaction plant parameters and process plan:designs the overall construction scheme of the LNG liquefaction plant engineering,technical process including acid technological process,the dehydration process,liquefaction process,liquefaction unit USES a binary mixed refrigerant refrigeration(DMR)liquefaction process,providing a complete set of liquefaction technology process plan;(3)Thermodynamic analysis and simulation of liquefaction process:determined the phase equilibrium calculation model of natural gas and mixed refrigerant,enthalpy and entropy calculation model;The thermodynamic model of the main equipment in the liquefaction process was established.Using HYSYS software and steady-state simulation method to analyze the main nodes and optimize the parameters.(4)Economic evaluation and benefit analysis:calculated the investment financial index of the liquefaction plant according to the product scheme and other given conditions;And the overall construction of the factory economic analysis and evaluation,and finally from the economic benefits,environmental benefits and social benefits of the Angle of evaluation.In this paper,based on the actual engineering application,the parameters were optimized and adjusted according to the actual situation,so as to reduce the energy consumption of natural gas liquefaction plant and improve the productivity efficiency.The results have great economic value,social benefits and environmental benefits,and have certain guiding and reference significance for the development of natural gas liquefaction process in China.