Design And Simulation Study On Cooking And Heating Stove Burning Coke Powder Briquette

At present,coal combustion is still the main way of cooking and heating for rural residents in northern my country.Since most of the civil coal is directly burned and discharged,it has caused a great burden on environmental protection.In particular,the emission of particulate matter has serious damage to the air pollution and the health of residents.Burning clean briquette and using the matching heating furnace can not only effectively reduce pollutant emissions,but also meet the living needs of residents,which is highly feasible and economical under the actual national conditions.As an industrial by-product with high calorific value,coke powder has high utilization value.Based on its flame retardancy,this paper blends straw and coke powder to prepare briquette to improve its combustion performance.The combustion characteristics and kinetic model of the coke powder briquette are studied through the customized thermogravimetric analysis system,and the matching cooking stove is designed according to its fuel characteristics.In addition,a fly ash deposition model was established based on the simplified two-dimensional flue structure of the stove,and the deposition characteristics of fly ash in different flue structures were numerically simulated for the purpose of particle capture.The main contents of this paper are as follows:(1)The weight loss process of large particles and large mass fuels at constant high temperature can be monitored in real time by the customized thermogravimetric analysis system(The maximum weighing value is 320 g,and the accuracy is 0.001 g),which can realize a visual human-computer interaction interface through the supporting software written based on the LABVIEW.The experimental data of the customized thermogravimetric analysis system was compared with that of the HTG-1 series thermogravimetric analyzer,which confirmed the reliability of the experimental device.(2)The customized thermogravimetric analysis system was used to conduct isothermal combustion experiment on the coke powder and straw blended fuels.The combustion characteristics of coke powder and straw at 800,900 and 1000℃were studied when the mixing ratio of coke powder and straw was 90:10,85:15,80:20,75:25 and 70:30,respectively.And the reaction kinetics parameters of briquette fuel were calculated by isothermal method.The results show that increasing of temperature and straw mixing ratio can improve the burning rate and shorten the burnout time.It is considered that straw improves the flame retardancy of coke powder.The reaction order of coke powder briquette with different blending ratios in constant temperature combustion at 800～1000℃varies from0.9 to 2.Both the activation energy and the fre-quency factor decrease with the increase of the straw blending ratio.When the straw content increases from 25%to 30%,there will be a sudden change in both of them,which is greatly reduced.(3)According to the combustion characteristics of coke pulverized briquette,the furnace volume heat release rate and grate heat release rate of the cooking and heating stove are determined to be 375 k W/m~3 and 200 k W/m~3 respectively,and then the fuel consumption of the stove is determined by the combustion calculation of the fuel on this basis.The main design parameters such as the furnace and the chimney are calculated based on the relevant literature.The cooking and heating stove designed in this paper is a forward-combustion stove with three-stage air distribution.The air intake from the bottom provides the air required for fuel combustion,the primary air supplements the inlet to assist the combustion of the accumulated fuel layer,and the preheated secondary air ensures the complete combustion of the fuel.The multi-return flue prolongs the residence time of the flue gas in the furnace,and the perimeter water tank and heat exchange tube ensure the thermal efficiency of the furnace.(4)Based on the simplified two-dimensional flue structure of the cooking stove,a particle deposition model of fly ash was established.The deposition characteristics of particles in different flue structures and the effect of particle size on deposition rate were analyzed.The results show that the addition of corrugated plates and baffles in the flue can realize the capture of fly ash particles,and the arrangement of corrugated plates and baffles has a great influence on the particle deposition rate;when the particle size is between 10 and2.5μm,the particles The deposition rate is proportional to the particle size,and when the particle size is between 2.5 and 0.1μm,the particle deposition rate is inversely proportional to the particle size.