用局部组成活度系数模型计算原油中石蜡沉淀量

APPLICATION OF COMPOSITION MODEL TO CALCULATION OF WAX PRECIPITATION FROM CRUDE

准确描述固相的非理想性是计算复杂流体的气液固相平衡的关键。从原油中沉淀出来的石蜡多由正构烷烃组成 ,其晶格结构主要是正交相 (斜方晶格 ) ,特别是在低温时可能是惟一的晶格结构 ,而局部组成模型能够较准确地描述正交相的非理想性。将局部组成活度系数模型用于复杂石油流体中石蜡沉淀量的计算 ,并与正规溶液理论模型进行了比较。结果表明 ,对于高温石蜡沉淀量的计算 ,两个模型均能给出较好的结果 ,但对于低温石蜡沉淀量的计算 ,局部组成活度系数模型能取得较满意的结果。

In the vapor-liquid-solid equivalence calculation of complex fluids, the key problem is to describe the non-ideality of solid phase. At the wax-appearance temperature, orthorhombic solid is the main phase existing in the wax precipitated from crude oil. Especially at a lower temperature, it may be the only lattice construction. A theoretical model based on the local composition concept can be used to describe the non-ideality of orthorhombic phase of n-alkanes. A local composition activity coefficient model was proposed and applied to calculate the wax precipitation from crude oil. The calculation result was compared with that of the regular solution model. It can be seen that the newly proposed model is better than the regular solution model for calculating wax precipitation at low temperature.