Application of implicit curve-fitting in the calculation of thermodynamic property of natural gas

The precision, velocity and stability for the calculation of property of natural gas have great impact on the numerical simulation of natural gas process. Therefore, the paper puts forward the implicit curve-fitting model of the thermodynamic property of natural gas, and gives the method of transforming from this model into explicit calculation. This method can ensure the reversibility of the calculation of thermodynamic property of natural gas, and meanwhile, because there is no iteration, it also ensures the absolute stability of the calculation of thermodynamic property. Taking the natural gas component of a domestic LNG terminal as an example, and the HYSYS calculation result as the data source, the model above is verified. The results show that the maximum relative deviation of this model in the fitting range is less than 1%, and the calculation speed is much faster than the LKP state equation. Since this method is accurate and highly efficient in simulation, it has a good prospect of widespread application in the process simulation of natural gas industry.