天然气节流温降机理模型

MODEL OF TEMPERATURE DROP MECHANISM WHEN GAS FLOWING THROUGH CHOKES

基于能量守恒原理和范德华混合规则 ,导出了天然气节流温降的数学模型 ,该模型采用Peng -Robinson方程描述天然气节流的相平衡过程。应用Brown焓熵图版数据进行实例计算 ,并将本模型计算结果与查焓熵图的值进行了对比分析。在天然气相对密度 0 .6～ 1.0、压力 0 .0 344～ 6 8.95MPa和温度 93.3～ 371.1℃的条件下 ,两种不同方法得到的计算结果十分吻合 ,其平均误差仅为 - 0 .2 1% ,平均绝对误差为 0 .5 5 % ,由此证明本模型的正确性且具有较宽的适用范围。应用本模型的计算机程序较查焓熵图版方法具有快捷、简便和适应性好等优点 ,为工程上进行采输工艺设计和生产动态分析 (如天然气水合物的预测和防止等 )

Based on energy conservation theory and Van Der Waals's mixed rule,a mathematical model is derived.The model describes the phase equilibrium process with Peng Robinson equation when gas flowing through chokes. Data acquired from the Brown enthalpy entropy diagram was used to calculate the real cases,comparing the results come from the model with the data from the enthalpy entropy diagram.Under the conditions of gas's density from 0.6 to 1.0,temperature from 93.3 to 371.1℃ and pressure from 0.034 4 to 68.95 MPa,the results acquired from the model matched well with the values from the Brown enthalpy entropy diagram.The average error was -0.21 % and the absolute average error of them was 0.55%.Therefore,it proved that the model is correct and has wide applicable scope.Comparing with the Brown enthalpy entropy diagram,the computer program of the model has the advantages such as quick calculation,convenient application and good adaptability,and provides an important tool for the engineering design of the gas recovery and transportation and the production dynamic analysis such as prediction and prevention of the gas hydrate.