CH4-CO2二元系中二氧化碳的结霜温度预测

Prediction of CO 2 frosting temperature in CH4-CO2binary system

关键词:  二氧化碳  结霜  气-固相平衡  液化天然气

Key words:  carbon dioxide  frosting  gas-solid phase equilibrium  LNG

摘要:

天然气低温液化过程中,温度低于三相点温度时,其中的CO2可能会凝华结霜。准确地对CH4-CO2二元系中CO2的结霜温度进行预测,将有助于天然气凝华脱除CO2的研究。根据气-固相平衡的原理,采用PR状态方程法对CH4-CO2二元系中CO2的结霜温度进行了计算,将计算结果、HYSYS软件和"固体CO2形成近似条件图"所得到的预测值与实验值分别进行了分析比较,结果表明三种方法都能获得较好的精度。此外,根据实验数据还拟合了一个经验函数用于预测二元系中CO2的结霜温度,可供粗略估算时使用。

Abstract:

When the temperature is lower than triple point of natural gas,CO 2 is likely to frost in the cryogenic natural gas liquefaction process.A precise prediction of CO 2 frosting temperature in CH4-CO2binary system will contribute to the study of CO2removal from natural gas by sublimation.The calculation of CO2frosting temperature in CH4-CO2binary system based on gas-solid phase equilibrium model was conducted by PR equation of state(EOS).The predicted value of PREOS,HYSYS simulator and Approximate Conditions of Solid CO 2 Formation chart were compared with experimental data,the results showed that the three methods were in good agreement with experimental data.Furthermore,according to experimental data,a empirical function was proposed to predict the frosting temperature of CO2in CH4-CO2binary system for rough estimate.