Modeling of entrained flow coal hydropyrolysis reactors. 1. Mathematical formulation and experimental verification

Abstract

A mathematical model has been developed to describe physical and chemical processes occurring in an entrained fbw coal hydropyrolysis reactor. The model is onedimensional and incorporates a detailed multistep reaction kinetic model developed by Johnson for hydropyrolysis supplemented by Suuberg's pyrolysis model for rapid reactions, reactions of hydropyrolysis products in the gas phase, hydrodynamics of the gas-solid system, sweliinghhrinking of the coal particles, and the heat transfer between the coal-char particles, gases, and reactor walls.

Pulverized coal conversion in downflow gasifier

“…As pressure increases, the deposition becomes significant, and the fraction of reactive volatile in the gas phase decreases and disappears at a pressure as high as 70atm. Equation (5) predicts very well the role of pressure in pyrolysis, as compared to experimental data reported in Reference 8. However, this equation was developed with the assumption that coal particles retain their porous structure and diameter during the period of pyrolysis.…”

“…With an increase of the total pressure, the mass fraction of volatile is decreased. The decrease of volatile produced with increasing pressure is attributed to the secondary reaction of the reactive volatile within the coal particles and is represented by equation (5). The non-reactive volatiles are insensitive to the increase of the total pressure.…”

“…However, this equation was developed with the assumption that coal particles retain their porous structure and diameter during the period of pyrolysis. Many coals undergo physical transformation at elevated temperature by swelling, changing in porosity, etc., and hence equation (5) will not be sufficient forithese cases.…”