Commissioning And Research Of Through-flow Domestic Waste Low-temperature Pyrolysis-combustion Furnace

The treatment of rural domestic waste is a hot issue under the theme of “rural revitalization” today.Under the background of small scale and strong dispersion of rural domestic waste,small-scale domestic waste pyrolysis has characteristics of large capacity of reduction,harmlessness,resource recycling and low secondary pollution,the development of this technology is receiving extensive attention.This paper is based on the demonstration project "Village and Township Domestic Waste High-value Utilization and Secondary Pollution Control Technology and Equipment" project,taking the domestic waste from residents around Tumen Town,Yunxi County,Shiyan City,Hubei Province as the processing and research objects.According to the decentralized rural life Based on the design principles of waste treatment equipment and the characteristics of local domestic waste,the process of pyrolysis treatment of domestic waste was designed,and the material and energy balance was carried out.On this basis,the overall process and system equipment are designed.The system includes domestic waste crushing pretreatment,belt feeding system,sealed hydraulic pusher feeding system,domestic waste pyrolysis furnace body,high-voltage electrostatic coke catcher,and second combustion Furnace and flue gas treatment system.The characteristics of local domestic waste were study through field visits,surveys and sampling analysis.According to the sampling results,the moisture content of the garbage is 30-50%,the low calorific value is 10806.85 k J/kg,H/C is 0.14.Under the conditions of high moisture content and crushing treatment,the uniformity of the material is improved,but the porosity is reduced.At present,no government-led waste classification measures is implemented in the local countryside,but the local villagers will spontaneously recycle beer bottles,cartons,and wood.In the production commissioning and operation test of the device,different grate designs and gas distribution methods were tested.And the influence of operating time,operating conditions,material moisture content,furnace body reaction temperature and other factors on furnace gas products was analyzed.The results show that active gas distribution leads to the highest temperature in the bottom of the pyrolysis furnace,which is stable above 600℃.When a total of 120 gas distribution pipe groups with a spacing of160mm×180mm are used,the bottom temperature and the top outlet gas temperature change the least,indicating the reaction state in the furnace is the most stable.The grate with a spacing of 40 mm has the best effect,and the loss of ignition of residua is 2.5%,but it will cause difficulty in slagging,and the residua will accumulate on the grate.The phenomenon of reaction layer drift and slagging occurred during multiple commissioning operations,which had a serious impact on the operation of the furnace.The analysis believed that these following factors play a key role.Gas distribution in the furnace was uneven.Alkali metal elements and alkaline earth metal elements in the biomass reduced the melting point of the mixed ash.The combustion layer temperature was too high.Based on the detection and analysis of the produced gas of the pyrolysis furnace for10 consecutive days,the content of combustible gas in the furnace-outlet-gas is 11%-16%,the content of CO₂ is 8%-17%,and the content of O₂ is less than 5%.In the combustible gas,CO accounts for 30%⁶0%,H₂ accounts for 25%⁵0%,and CH₄ accounts for5%²0%.Since the moisture content of the incoming materials is 30% to 50%,the pyrolysis and gasification reaction in the furnace is not only affected by the air,but also by water vapor,so that the produced gas contains a large amount of H₂.This result has reference significance for process and equipment design in future.The tar concentration measured by the isopropanol absorption method is about 12.82g/Nm³.The high-voltage electrostatic tar catcher captures tar with a water content of 25% and ash content of1.75%.The main volatiles escape at around 133℃and 297℃.The volatiles are mainly CO,olefinic acid,benzene ring tar,etc.The tar has poor fluidity and starts to layer when heated to 90℃.