STUDY OF CHAR COMBUSTION USING SHRINKING REACTIVE CORE MODEL RESULTING FROM BIOMASS PYROLYSIS

Abstract

A number of studies have been carried out for the combustion of coal by different types of model i.e. shrinking core model, shrinking reactive coal model, random pore model, etc. Some of them are briefed as follows. Everson et al. [9]in their paper have studied about char combustion under pressurized fluidized bed combustion process, and overall study of char combustion model is done. They used high ash content char particle for their study.The ash content was above 40% and calorific value was low. They used PBFC(pressurized fluidized bed combustion)in place of PFC(pulverized fuel combustors) because PFC has some disadvantages such as pollutant concentration is high and are technically difficult to handle. For experimental results,Thermo Gravimetric Analyzer (TGA)was used and experimental data was compared with model equation predictions. Experiments were carried out at 487kPa and temperature in therange from 750°Cto 950°C. They introduced the concept of variation in carbon concentrationfor showing the effect of high ash content. The model which they used for combustion process was shrinking reactive core model and experimental data agreed well with this model. Experimental results at different temperature and pressure were compared with model and effects of various parameters such as conversion withtime were discussed. In their investigation, they found that at higher temperature, value of Thiele modulus was large, it was not sufficient enough to describe shrinking core model. At temperature greater than 950°C, they found that shrinking reactive core model gives exactlythe same results as obtained from shrinking core model.Following graphs shows the investigation of different parameters as done by Everson et al. [9