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Cotton is an important cash crop in China, the cotton straw produced after cotton harvest is an important biomass energy. In view of the environmental problems existing in the traditional utilization of cotton straw, it is of great significance to transform cotton straw from agricultural waste to biochar. Based on the research of biochar processing equipment for cotton straw at home and abroad, it can be found that biomass carbonization equipment is mainly divided into microwave cracking carbonization and traditional electric heating carbonization. The traditional carbonization technology has the disadvantages of uneven carbonization and low carbonization efficiency. The traditional carbonization technology has the disadvantages of uneven carbonization and low carbonization efficiency, microwave cracking carbonization can not only improve carbonization homogeneity, but also shorten carbonization time. In order to improve the carbon yield of cotton straw and analyze the effect of different operation parameters on the carbon yield of cotton straw by microwave pyrolysis, a microwave cracking equipment was developed in this paper. The microwave cracking equipment was mainly composed of gas-liquid treatment system, cracking chamber, inert gas supplying system, constant temperature control system and so on. The key component of the equipment was the magnetron device in the cracking chamber, the magnetron device provided energy for the pyrolysis and carbonization of the cotton straw. Taking the moisture content of cotton straw, carbonization time and microwave power as the experimental factors and the carbon yield of cotton straw as the index, the response surface tests of three factors and three levels were carried out for the microwave cracking process of cotton straw. The quadratic polynomial response model of cotton yield of cotton straw to experimental factors was established. The significant order of the influence of each experimental factor on the carbon yield of cotton stalk was determined as water content of cotton straw, microwave power and carbonization time. Optimization of operation parameters was carried out by box benhnken combined test method, the result was that the moisture content of the cotton straw was 11%, carbonization time was 6 min and microwave power was 1.8 kW, at this time, the carbon yield reached 31.61%. The verification test results showed that under the optimal parameter conditions, the carbon yield of cotton straw was 30.9%, and the relative error with the theoretical value was 0.71%, the designed microwave cracking equipment basically meet the design requirements. The results can provide reference for the design and operation parameters optimization of microwave cracking equipment for cotton straw. [ABSTRACT FROM AUTHOR]

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