含油污泥蒸汽热解循环工艺研究

针对含油污泥蒸汽热解工艺存在蒸汽发生能耗高、热解气冷却所需循环水量大和废水排放量大等问题,提出了一种蒸汽循环热解处理含油污泥新流程。通过模拟计算,考察了蒸汽循环比例对饱和蒸汽发生用脱盐水量、废水量、循环冷却水量、电功率、综合能耗和单位能耗等的影响。结果表明:与蒸汽未循环流程相比,蒸汽循环流程可以显著降低饱和蒸汽发生用脱盐水量、循环冷却水量、废水量、电功率、综合能耗和单位能耗。采用蒸汽循环工艺,实现了能量物质的综合利用。

基于不同热解方式下烟煤裂隙结构演化的对比

煤炭地下原位热解开采是未来煤炭资源利用的新趋势,探明不同热解方式下煤的孔裂隙结构、空间分布及连通性尤为关键,现有的关于煤热解后孔裂隙结构参数的研究均处于无应力状态且缺乏不同热解方式下孔裂隙结构参数的对比。基于以上不足,利用自制的高温高压热−流体−应力−化学耦合作用的三轴试验机,结合显微CT技术,探究了烟煤在自然、蒸汽原位热解(600℃)条件下的裂隙结构差异,进而就差异性进行了机理探究。结果表明:①自然、蒸汽600℃原位热解后,煤样内部产生的裂隙形态以细长型裂纹及孔洞为主,蒸汽热解后裂隙尺度进一步提升,裂隙网络更为丰富复杂;②在轴压5 MPa、围压3 MPa的应力条件下,烟煤自然热解后裂隙率为原始裂隙率的2.68倍,蒸汽热解后裂隙率为原始裂隙率的3.65倍且每一层位裂隙率更均匀;③蒸汽热解使得烟煤受热均匀,换热面积大,有机质热解更加充分。驱替作用保证热解产物的持续产出;孔隙压力的局部应力作用既扩大了原有的孔裂隙体积又会破坏孔壁弱面,大大增加了孔裂隙连通性;蒸汽剥蚀效应将盲孔及孔裂隙附着的黏稠度较高的焦油“冲刷−运移”至煤体外;富氢环境促进了重质焦油的裂解,增强了油品的流动性;④原位与无应力状态煤样热解裂隙率及裂隙形态存在较大差异,蒸汽热解是煤炭原位注热开采工程实践的最优加热方式。

Energy and Exergy Analysis of a Novel Efficient Combined Process by Hydrothermal Degradation and Superheated Steam Drying of Degradable Organic Wastes

This paper considers the combination of hydrothermal degradation （HTD） and superheated steam （SHS） drying in disposal and processing of degradable organic wastes in municipal solid wastes （MSW）. In SHS drying, a fraction of dryer thermal energy input can be recovered and used to satisfy the heat requirement in maintaining the HTD operating temperature. Both energy and exergy analysis are applied to the combined process. The analysis covers ranges of dryer inlet temperatures of 202.38-234.19~C and feed water content of 32.5-65%. Thermal energy analysis shows that the combination of HTD and SHS drying can achieve thermal energy self-sufficiency （TES） by manipulating process variables. The exergy analysis indicates the location, type, and magnitude of the exergy losses during the whole process by applying the second law of thermodynamics.