Research On The Combustion Characteristics And Pollutant Emission Of Novel Coal Pellets

Heating by raw coal combustion has considered to be the main reason for indoor and outdoor air pollution in rural northern China.In recent years,China has proposed a variety of clean heating solutions to replace raw coal burning.However,due to many factors such as high renovation and operating costs and insufficient energy supply,raw coal combustion is still the main heating method in underdeveloped areas.There is of great significance about using coal by a clean and sustainable combustion.In this study,bituminous coal,which is the most widely used and most abundant resource in rural areas in China,was used as the research object,and two types of novel pellet fuels,novel bituminous coal pellet fuel and biomass-coal pellet fuel were designed and developed respectively.Based on the thermogravimetric analysis system and real-time pollutants emission monitoring system for a comprehensive assessment of combustion characteristics and their emission reduction of pollutants.The experimental results show that,compared with the fuel powder,the forming effect effectively slows down the precipitation rate of volatile matter in the fuel.The comprehensive combustion characteristics of the fuel after forming are decreased,and the activation energy is increased.The PM_2.5 and CO emission factors of the new bituminous briquettes are 1.36-2.29 g/kg and 11.1-18.0 g/kg,respectively.Compared with the bituminous coal,the PM_2.5emissions are reduced by 83%-90%,and the CO emissions are reduced by 61%-76%;the ash melting point of the new bituminous pellet briquette is higher（over1300°C）,which can effectively overcome the problem of easy slagging of fuel compared with commercial biomass pellets.The combustion of biomass-coal composite granule briquette is mainly divided into two stages:volatile release combustion and fixed carbon combustion.The kinetic models of both stages are first-order chemical reaction models,and with the increase of biomass ratio The maximum burn rate and burn index of the composite fuel are increased.The activation energy of the wheat straw composite fuel with the biomass/coal ratio of 1:2 was the lowest,and the activation energies of the two stages were 25.91 k J·mol^-1 and 3.82 k J·mol^-1,respectively.The composite fuel has a significant effect on PM_2.5 and SO₂emission reduction,reducing 17%-84%and 21%-85%respectively to the bituminous raw coal,but the emission reduction effect on CO and NOx is not obvious.The addition of biomass to pelletized coal will increase the risk of burning coke to a certain extent.This study has mastered the combustion characteristics and pollution emission characteristics of bituminous coal pellets,and proposed a design plan for using raw coal to prepare coal pellets.The realization of clean heating in rural areas points out a new technical method.