Natural Gas Liquefaction Process Simulation And Optimization

The nature gas is considered as a kind of new first-advocated energy sources at twenty-first century for its characteristic of high quality and pollution-free to the environment. The physical volume of the nature gas is only 1/625 for the original volume after liquefied at low temperature. This doing is very convenient for its conveyance and storage. The liquefaction of nature gas has become an important and advanced technology and liquefied natural gas (LNG) have developed to a new, fast-growing industry by now. This text which sets out from the thermodynamics make an exact research in simulation and optimization of the liquefied process of nature gas, the aim of which is to reduce the sum of the power consumption and add the LNG's output.At first the principle of the liquefied technology to the nature gas is introduced and the fundamental regulation for the choice and design is given out through the analysis to these characteristics that all kinds of modern common-using liquefied cycles in use of nature gas have. 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. In this paper according to the complication of the thermodynamic properties of nature gas and mixture refrigerant, the author chooses the SRK 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. All these resolve calculations of the thermodynamic properties of mixture in simulationIn the study of establishing the mathematic models for the equipments in the simulation of the liquefied process of nature gas, these model are concluded and improved by module, which consists: (1)compressor; (2)expander and throttle valve; (3) separator; (4)mixture; (5)multi-flow heater exchanger. The good effects are showed in the calculation and 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 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.At last 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. At the same time a beneficial discuss about the way of the optimization to the liquefied process according to every kind of term's stipulation in the simulated calculation is carrying out.