油页岩流化床燃烧过程中灰粒自脱硫的数学模型

MATHEMATICAL MODELLING OF DESULPHURIZATION BY ASH PARTICLE DURING FLUIDIZED BED COMBUSTION OF OIL SHALE

在耦合辐射、对流和传导三种形式的传热及氧气与二氧化硫传质和化学反应动力学的基础上，首次建立了油页岩灰粒固硫的等温和非等温模型，考虑了由于氧化钙在灰粒中含量较少，且呈微细粒均匀分布，固硫过程中不发生堵孔现象的潜在优势。模型计算结果表明，在６～１０ｍｉｎ内，钙的利用率＞５０％。这显示了油页岩由于其独特的高灰分含量，灰分在流化床燃烧工艺中将发挥固硫作用。颗粒页岩灰固硫属非催化气固反应，传统的研究方法是采用准稳态假设，其结果影响了模型的精度和应用。本研究则考虑了时间变量，建立了气固颗粒反应的瞬态模型，并通过对模型中偏微分方程的离散化处理，开发了一个有界Ｗｅｇｓｔｅｉｎ数值求解方法。此方法具有收敛快、计算精度高等优点。

Based on heat transfer in the forms of coupling radiation,convection and conduction,also with the mass transfer of O 2 and SO 2 and the intrinsic kinetics of the chemical reactions,an isothermal as well as a non isothermal model for SO 2 capturing by oil shale ash particles were established.Attention was paid to the potential advantages of no pore blockage in the SO 2 capturing process,the extra low content of calcium oxide and its highly uniform distribution existing as fine particles in the oil shale ash,and as predicted by the established model,that in 6～10 minutes during combustion,the utilization of calcium in the ash particles is higher than 50%.This implies that oil shale ash will play an important role in SO 2 capturing due to the unique high content of ash in raw oil shale in fluidized bed combustion of oil shale.In this paper,taking time as a variable,non catalysed gas solid reaction models were developed in a transient nature.By scattering a series of partial differential equations,a numerical method called limited Wegstein of quick convergence and high precision is deduced.