| As China's strategic reserve resource,food has caused a lot of economic losses due to moisture during storage every year.Due to the great pollution of coal combustion,it is of great significance to use biomass to substitute coal for drying food.In this paper,biomass two-stage gasification and melting combustion technology is proposed for grain drying,and rice straw husks and rice hulls are used as raw materials to conduct relevant experiments.First,low-temperature air gasification of rice straw and husk was studied using a bubbling fluidized bed.The effects of temperature,equivalence ratio,and moisture content on the gasification characteristics of straw,tar cracking,and carbon residue composition were analyzed and compared with rice hulls.The results showed that increasing the temperature can significantly improve the straw gasification effect,increase the calorific value of gas production and gasification efficiency,and at the same time,it can also promote tar cracking and increase the conversion rate of fixed carbon.Increasing the equivalence ratio can significantly increase the gas production rate,but at the same time it will reduce the gas production calorific value.The gasification efficiency increases first and then decreases.At the same time,increasing the equivalence ratio can reduce the tar concentration in the gas production and increase the fixed carbon conversion rate;In comparison,rice husk gasification is better,the calorific value of gas production,gasification efficiency,and fixed carbon conversion rate are both higher than that of straw and the tar content is even lower.Increasing the moisture content will weaken the overall gasification effect,the gasification efficiency and the fixed carbon conversion rate will decrease,the gas production calorific value will decrease,and the tar content will decrease.Secondly,using the thermogravimetric analyzer to study the combustion characteristics of the carbon residue obtained by gasification,compare the difference between the raw material and the carbon residue,and analyze the influence of different gasification conditions on the combustion characteristics of gasification residual carbon.The test results show that compared with rice straw and rice husk materials,residual carbon shows a characteristic of single peak weight loss,high ignition temperature,low maximum weight loss rate,and poor ignition performance.In contrast,increasing the equivalence ratio of gasification and reducing the moisture content of raw materials will reduce the content of volatiles in the residual carbon,which will weaken the ignition performance of carbon residue.Finally,on the basis of laboratory research,a two-stage gasification and melting combustion pilot demonstration test device such as East Biomass was set up to carry out cold state commissioning and hot state test of straw rice husks to analyze the stability of the system and the fluidized bed.The effect of the equivalence ratio on the operation of the system.The test results show that the temperature stability of the fluidized bed furnace and cyclone furnace is good,and the gasification characteristics of the fluidized bed are in line with the laws obtained in the laboratory,but the overall efficiency is better.The temperature of the cyclone furnace can be stably operated above 1200°C,and the fuel can be fully burned.The incomplete combustion losses of rice straw and rice husk are 0.17% and 0.40%,respectively,and the highest collection efficiency of the ash can reach 92.49% respectively.92.79%.The average fuel combustion efficiency can reach over 98%.Under the condition of ignoring the heat loss,the overall thermal efficiency of the system can be as high as 98.6%.The thermal economy is good and has good promotion value. |
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