Research on Physical Properties and Data Processing in the Process of Removing Acid of LNG
|School||Harbin Institute of Technology|
|Course||Refrigeration and Cryogenic Engineering|
|Keywords||Natural gas Property Phase equilibrium GA Nerve network|
The properties of natural gas are absolutely necessary in the air conditioning process and the veracity of natural gas properties is the key of a good conditioning process design. But the experiment data is limited, so it is necessary to calculate them. In this paper, we discuss how to calculate the density、enthalpy、entropy、viscosity of natural gas and the viscosity、surface tension of chemical absorbent.In this paper we introduce Lee-Kesler equation and RKS equation to calculate the density、enthalpy、entropy of natural gas, and compare the result with experiment data. After this we can know their precisions, so we can decide which equation to choose in different conditions. In order to calculate the viscosity of natural gas, we introduce the Chung method based on theory and the Lucas method based on the law of corresponding states, and compare the result with experiment data, so we can determine their precisions and the range they are applicable.Sometimes we have to calculate phase equilibrium in the conditioning process. So in this paper, we derive the expression of fugacity of Lee-Kesler equation and RKS equation, on top of this we calculate the phase equilibrium by the two methods, and compare the result with the experiment data.The chemical absorbent is strong polar fluids, so we decide to introduce Teja-Rice method to calculate its viscosity. For surface tension of liquid, there is no method that performs very well, we decide to use Simply Add method briefly. The methods we mention in front have a lot of parameters not assured, we have to calculate them by data regressing. In this paper, we write a program of GA(genetic algorithm) based on best preserving policy, and then conform its validity. On top of this, we regress the one order interaction coefficient of Teja-Rice method, then we use it to calculate the viscosity of MEA solution and compare it with the result calculated by Aspen Plus. After this we can know the precision of Teja-Rice and the range that is applicable.In the chemical design, there may be a lot of experiment data, but because of the faultiness of existing theory, we can’t deal with the experiment data effectively. In this paper, we decide to deal with the experiment by BP network, and plan to use it to calculate the phase equilibrium of CO2-MDEA-PZ-H2O system. This introduces a new method to deal with the experiment data.