秸秆燃烧中KCl逸出的原位共熔蒸发模型

A Model Describing Evaporation of KCl After In-situ Eutectic Melting During Combustion of Agro-stalks

为研究秸秆燃烧中KCl的逸出规律,对KCl,KCl和SiO_(2),KCl和K_(2)SO_(4),KCl、K_(2)SO_(4)和SiO_(2),纯秸秆灰(玉米秸/麦秸/稻秸)进行了热重实验。发现秸秆燃烧中KCl共熔后的蒸发是钾逸出的主要方式之一。结合KCl饱和蒸气压规律、拉瓦尔定律等,建立了秸秆燃烧中KCl逸出的原位共熔蒸发模型。应用气相区解析解和气液共存区隐式数值求解,编程对KCl逸出过程进行了分析。结果表明:固相温度控制在700℃以下可有效控制KCl的逸出。原位共熔蒸发模型可描述KCl逸出特性和趋势(多数情况下相对误差<15%),获得物性数据可进一步提高模型精度。

In order to predict the release rate of KCl during the combustion of agro-stalks,thermal behavior of KCl,KCl+SiO_(2),KCl+K_(2)SO_(4),KCl+K_(2)SO_(4)+SiO_(2),and pure agro-stalks ash(corn stover/wheat straw/rice stalk)was analyzed.According to their experimental results,evaporation of KCl after its eutectic melting with other salts was found to be one of the main release routes.A model to describe the evaporation of KCl after in-situ eutectic melting was established on the basis of Raoult’s law and characteristic of saturated vapor pressure of KCl.Combined the implicit numerical solution for vapor-liquid area and the analytical solution for vapor area,a code was written and the release rate of KCl was calculated.Results show that the release of KCl can be effectively inhibited via controlling the temperature of condense phase<700℃.The characteristics and trends of KCl release can be well predicted by the model with a relative error<15%in most cases.More accurate prediction can be obtained if more accurate property data are accessible.