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China is rich in crop straw resources, but straw burning is serious and resource utilization is not high. To solved the ecological pollution and resource waste caused by straw burning, and let straw carbonization equipment market promotion. The orthogonal experiment of carbonization process was designed according to the literature and the results of preliminary experiment. The straw biochar produced by process test was analyzed. The thermal characteristic parameters and combustion characteristic parameters were calculated. Straw biochar yield, fuel ratio, hydrocarbon atomic ratio, alkalinity index, high calorific value and dimensionless comprehensive combustion index Z were used as quality evaluation indexes for high quality straw biochar. Grey correlation analysis method and comprehensive quality score method were used to analyze the evaluation indexes and influencing factors, and the response surface method designed by CCD experiment was used to optimize the production process of straw biochar directional regulation. The experiment provides a theoretical basis for improving the energy utilization rate of straw and provides a large number of data support for the popularization and application of continuous straw carbonization equipment. The results showed that temperature was the primary factor affecting the quality of straw biochar. The five evaluation indexes of straw biochar quality except the yield of straw biochar were ranked as follows: Z > H/C >FR >AI >HHV, the quality of straw biochar produced by the equipment is stable and close to the burning quality of bituminous coal. In the orthogonal experiment, the experiment in group 16 and group 12 obtained a higher comprehensive score, and the optimal process parameter combination was A3B4C1. CCD test results after response surface optimization, in the balance of the two response values to meet the maximum, the predicted optimal process parameters are: cut after the corn straw, after 600 ℃ thermal carbonization for 50 min, the production of straw biochar output is 53.05%, its combustion index Z is 0.726 6. The empirical test showed that the difference between the experimental value and the predicted value was less than 0.2%, the fitting model and the response surface optimization method were accurate and feasible, and the combustion quality of straw biochar produced by the optimal carbonization process was greatly improved. The C content and H/C of straw biochar produced under the best technological conditions are increased by nearly 2 times, which is closed to the combustion quality of bituminous coal and anthracite, and far better than the barbecue biochar purchased in the market. Through the carbonization process in this study, the utilization quality of straw biochar can be controlled directionally, forming a reproducible and generalized quasi-directional regulation method of high quality fuelized straw biochar. The analysis methods greatly reduce the experiment times, choose the appropriate fuel straw biochar quality evaluation index, and on the premise of saving the cost of raw materials and energy, quick understanding of high quality energy straw biochar production process parameters, facilitate continuous piecewise uniform crop straw carbonization market-oriented all-round production system of rapid popularization and application.In addition, the experimental design and data analysis method in this paper can also provide data support for the production of straw carbonization process using straw as raw material for adsorption and fertilizer carbon. [ABSTRACT FROM AUTHOR]

Crop straw is a valuable biomass energy resource and raw material for livestock forage, organic fertilizer and industrial use. However, the comprehensive utilization level of straw resources in China is not high due to various reasons including agricultural intensification, capital shortage and farmers’ cognition. Regional, seasonal and structural surplus of crop straw is common in China and a lot of straw is discarded and burned casually, especially in rural areas. It is not only a huge waste of resources, but also leads to serious atmosphere and soil environment pollutions. Thus, it is of great importance to improve the straw utilization rate. That take regional planning as a whole and realize full utilization of the regional total straw resources is a good strategy. Assessment of regional straw resources’ quantity, type, and distribution pattern is the prerequisite to achieve regional straw resources full utilization. In addition, the utilization modes and levels of straw resources are also restricted by many other factors including the social and economic development status. Thus, to make better use of straw resources and optimize utilization structure, it is necessary to take all the above factors into comprehensive consideration, carrying out scientific layout and rational planning. Hunan province is an important agricultural province and also a main producing area of double cropping rice in China. The present study estimated the straw quantity and amount per capita of the main crops in Hunan province. The spatial distribution patterns of straw resources in Hunan province were also analyzed. In addition, the paper also analyzed the potential of full utilization of the total straw resources in the province through comparing the current straw utilization structure and quantities with their corresponding competitive straw demands. The results showed that the theoretical and collectable amount of the main crop straw resources in Hunan province in 2018 were 4 021.7× 104 t and 3 039.1×104 t, respectively. The mean amount per capita of straw resource is only 0.68 t, which is much lower than the national average level. The straw of rice, rape, maize and vegetables accounted for 64.7%, 16.0%, 6.1% and 7.5% of the total straw resources of the Province, respectively. The various types of crop straws exhibited different spatial distribution patterns. The amount of rice, rape and vegetable straw increased from west to east and south to north in the province, whereas corn straw displayed an opposite distribution trend. Through estimating the potential utilization ways of straw resources, the competitive demand of straw in Hunan province included 887.3×104 t for fertilizer, 885.1×104 t for fodder, 65.7×104 t for raw material and 83.2×104 t for stroma material. The remaining amount of straw for potential energy utilization was 1 117.9×104 t. Considering the current straw utilization structure and the results as above, the overall trend of realizing full utilization in the province should be to improve the ratio of fodder and energy utilization and slightly reduce fertilizer utilization on the basis of maintaining the amount for stroma and raw material utilization. [ABSTRACT FROM AUTHOR]