Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned...Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned to soil,thereby seriously undermining biochar＇s efficacy. Therefore, the transformation mechanisms of biochar p H,mass, nutrients and metals during pyrolysis under different atmospheres and temperatures were studied such that the best method for biochar preparation could be developed. Several conclusions can be reached：（1） a CO2 atmosphere is better than a N2 atmosphere for biochar preparation, although preparation in a CO2 atmosphere is not a common practice for biochar producers;（2） 350 ℃is the best temperature for biochar preparation because the amount of nutrient loss is notably low based on the premise of straw transferred into biochar; and（3） transforming mechanisms of pH, N, P and K are also involved in the biochar preparation process.展开更多
Considering high-moisture municipal solid waste(MSW)of China,a steam dried MSW gasification and melting process was proposed,the feasibility was tested,and the mass and energy balance was analyzed.Preliminary experime...Considering high-moisture municipal solid waste(MSW)of China,a steam dried MSW gasification and melting process was proposed,the feasibility was tested,and the mass and energy balance was analyzed.Preliminary experiments were conducted using a fixed-bed drying apparatus,a 200 kg per day fluidized-bed gasifier,and a swirl melting furnace.Moisture percentage was reduced from 50%to 20%roughly when MSW was dried by slightly superheated steam of 150℃-350℃ within 40 min.When the temperature was less than 250℃,no incondensable gas was produced during the drying process.The gasifier ran at 550℃-700℃with an air equivalence ratio(ER)of 0.2-0.4.The temperature of the swirl melting furnace reached about 1240℃ when the gasification ER was 0.3 and the total ER was 1.1.At these conditions,the fly ash concentration in the flue gas was 1.7 g·(Nm^(3))^(-1),which meant over 95%fly ash was trapped in the furnace and discharged as slag.85%of Ni and Cr were bound in the slag,as well as 60%of Cu.The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97%when MSWis dried by steam of 200℃.The boiler heat efficiency is sensitive to three important parameters,including the temperature of preheated MSW,the moisture percentage of dried MSWand the fly ash percentage in the total ash.展开更多
基金Supported by the National Natural Science Foundation of China(No.41571283)
文摘Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned to soil,thereby seriously undermining biochar＇s efficacy. Therefore, the transformation mechanisms of biochar p H,mass, nutrients and metals during pyrolysis under different atmospheres and temperatures were studied such that the best method for biochar preparation could be developed. Several conclusions can be reached：（1） a CO2 atmosphere is better than a N2 atmosphere for biochar preparation, although preparation in a CO2 atmosphere is not a common practice for biochar producers;（2） 350 ℃is the best temperature for biochar preparation because the amount of nutrient loss is notably low based on the premise of straw transferred into biochar; and（3） transforming mechanisms of pH, N, P and K are also involved in the biochar preparation process.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50806013)the National Basic Research Program of China(No.2010CB732206)Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20070286074).
文摘Considering high-moisture municipal solid waste(MSW)of China,a steam dried MSW gasification and melting process was proposed,the feasibility was tested,and the mass and energy balance was analyzed.Preliminary experiments were conducted using a fixed-bed drying apparatus,a 200 kg per day fluidized-bed gasifier,and a swirl melting furnace.Moisture percentage was reduced from 50%to 20%roughly when MSW was dried by slightly superheated steam of 150℃-350℃ within 40 min.When the temperature was less than 250℃,no incondensable gas was produced during the drying process.The gasifier ran at 550℃-700℃with an air equivalence ratio(ER)of 0.2-0.4.The temperature of the swirl melting furnace reached about 1240℃ when the gasification ER was 0.3 and the total ER was 1.1.At these conditions,the fly ash concentration in the flue gas was 1.7 g·(Nm^(3))^(-1),which meant over 95%fly ash was trapped in the furnace and discharged as slag.85%of Ni and Cr were bound in the slag,as well as 60%of Cu.The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97%when MSWis dried by steam of 200℃.The boiler heat efficiency is sensitive to three important parameters,including the temperature of preheated MSW,the moisture percentage of dried MSWand the fly ash percentage in the total ash.
