Natural Gas Liquefaction Process Simulation And Optimization

After liquefied at low temperature,the volume of the natural gas is only 1/625 for the original volume,this doing is very convenient for its conveyance and storage.Now,the liquefaction technology of natural gas is a new and advanced technology,liquefied natural gas (LNG) have developed to a new,fast-growing industry by now.In the thesis,the research in simulation and optimization of the LNG are studied from the thermodynamics,the aim of which is to reduce the sum of the power consumption.At first,the simulation technology of the liquefied natural gas process is introduced for the actuality and development.The nature gas and the mixed refrigerant all are diverse mixture,therefore the change of their composition in the process make the liquefied process very complicated.Aim at the complexity of the nature gas and the mixed refrigerant,choosing the PR equation and the LKP equation to calculate the phase equilibrium properties and the enthalpy and entropy on the basis of giving the proper rules of mixing.In the study of establishing the mathematic models for the equipments in the simulation of the liquefied process of nature gas,these models are concluded and improved by module,which consists:compressor,expander,separator,mixture,multi-flow heater exchanger,this settle a good basis for the thermodynamic simulation of the liquefied process of the nature gas.Then the simulated calculation to the whole liquefied process of the nature gas is going on and the pressure,temperature,enthalpy, the flux of vapor and liquid,the mol percentage of vapor and liquid of every point are obtained,the same is true of the power of the compressor,the cooling provided by the propane cycle,the flux of the refrigerant,the exchanged heat of each heat exchanger.From the thermodynamics,the influences by which the process's parameters have effects on the performance of the typical liquefied process are exactly and fully analyzed,which consists:the press and temperature of nature gas,the mol composition of the nature gas,the storage press and temperature of the LNG.The aim function is the least for energy loss of compressor and the energy of the propane pre-refrigeration, establishing the optimization model of the liquefied process, optimizing the Propane-Mixed Refrigerant Cycle by pinch technology.