Co-torrefacton of Sewage Sludge and Leucaena by Using Microwave Heating

• Main Authors: Hsuan-Te Sung, 宋宣德
• Other Authors: 李公哲
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/17255640171444307879

碩士 === 國立臺灣大學 === 環境工程學研究所 === 103 === Due to the demand for fossil fuels which have been mined intensityly since the industrial revolution in the eighteenth century. However, under the conditions of limited resources, alternative energy must be found. Biomass can be considered as a potential energy development via common wastes conversion, such as agricultural waste, and animal waste. This study was carried out by microwave-induced torrefaction, which is a thermo-chemical convertion techmology to react mixed materials, including sludge and leucaena which acts an additive to improve product properties. The microwave heating reaction compared to conventional heating, not only reduces energy consumption but enhances the efficiency of the reaction. Torrefaction reaction is mild pyrolysis treatment which retains higher contents of biochar. Solid analysis items comprise of thermal gravimetric analysis, weight yield, energy analysis, calorific value analysis, approximate analysis, and LCA were used to analyze the impact and benefit of the input and output. The microwave was set to operate for 30 minutes at 100 W to 400 W and 100 W to 350 W. The sludge mixing ratio used was 25 %, 50 %, and 75 %. The results showed that the sludge material measured by thermal gravimetric analysis (TGA) lost most of its weight at temperatures between 200 ° C to 500 ° C. As power increased, mass decreased. After the microwave power rose to 250 W, the remaining sludge was less than half of the raw material, and as low as 20.48 wt. % at 400 W. When the microwave power was at 100 W, the sludge mixing ratio increased from 0 % to 25 % and to 50 %, showing a strongly decreased, indicate that sludge co-torrefaction can improve the overall situation. In addition to the calorific value of the sludge produced is greater than the raw sludge at 100 W, remaining power options is less than raw materials. When the material of sludge ratio 25 % was at 100 W, the product property can be close with calorific value of the leucaena product, indicate that the product can retain the value of the property at low mixed ratio and low power. When the power was from 250 W to 400 W, the proportion of remaining volatile content was between 1.9 to 4.8 %, ash content was increased from 64.61 to 72.34 %, fixed carbon was between 30.63 to 25.74 % for the torrefied product of the sludge. The property of low-volatile bituminous coal was close to the ratio of H/C of the product at 300 W for the torrefied product of the sludge on the Van Krevelan Diagram. The product properties at 350 W and 150 W were close to the low volatile bituminous coal at sludge ratio 25 % and 50 %, respectively. In the life cycle assessment, the major costs of sludge were water content (85 %) up to 292 kWh in the oven-drying unit, indicate the water content of the sludge represents a significant indicator for sludge treatment. Sludge co-torrefaction can not only reduce drying costs but retain higher the calorific value.