有机污染土壤异位直接热脱附装置节能降耗方案

以异位直接热脱附技术的原理、适用范围、工艺流程、优缺点等为基础，建立了输入、输出能量平衡关系式并进行了热平衡计算；针对该工艺能耗过高的问题，分析了系统各部分能耗，提出了节能降耗方案。通过烟气热回用装置，将二燃室后高温烟气余热能量经循环管道输送给土壤预干燥装置，将有机污染土壤含水率降低，从而减少系统总能耗。结果表明：经过热力计算，土壤水分预干燥量越大，系统节能效果越好；烟气余热足够用于土壤预干燥减少17%左右土壤水分的要求。通过土壤预干燥装置将土壤水分从20%降低到15%，可使直接热脱附装置降低能耗20%以上。

Energy-saving and consumption-reducing scheme for direct thermal desorption of organic contaminated soil

With the implementation of the policies ‘relocation of industrial enterprises in the old city to the suburbs’ and ‘re-planning of residential land for residential use’ in our country, the possible environmental heath problems resulting from the organic pollution sites left during the relocation of high pollution chemical enterprises need to be resolved, it is urgent to carry out the contaminated soil remediation. Ex-situ direct thermal desorption is one of the main techniques for contaminated soil remediation. Based on the principles, application scope, process flow, advantages and disadvantages of the ex-situ direct thermal desorption technology, the input and output energy balance equations were established and the heat transfer balance was calculated. Aiming at the high energy consumption, the energy consumption of each part was analyzed and the energy saving plan was raised. The flue gas reusing device was used to transfer the waste heat energy from the high-temperature flue gas after the second combustion chamber to the soil pre-drying device through the circulating pipeline. The moisture content of the organic polluted soil decreased, and the total energy consumption of the system was significantly reduced. According to the thermodynamic calculation, the more moisture of the soil decreased, the more energy could be saved. Flue gas waste heat was enough to reduce soil moisture by about 17% for soil pre-drying. According to the analysis, due to the limited continuous drying capacity of soil, the reduction of soil moisture from 20% to 15% with the soil pre-drying device could reduce the energy consumption by more than 20% for the direct thermal desorption device. The feasibility, advantages and disadvantages, and application scope of the disc continuous dryer and the rotary kiln dryer as the soil pre-drying device were compared. This study provides the reference for the selection of direct thermal desorption and energy-saving devices.