NUMERICAL SIMULATION AND EVALUATION OF INDIRECT THERMAL DESORPTION EQUIPMENT FOR PETROLEUM HYDROCARBON CONTAMINATED SOIL
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摘要: 针对土壤中石油烃热脱附机制不清的问题,创建了土壤侧与烟气侧耦合传热仿真模型,并将土壤侧的传质过程简化为变比热条件下的传热过程,耦合扩散火焰燃烧模型、灰气体加权和模型与离散坐标辐射模型,对国内工业化应用的热脱附设备进行了数值模拟。结果表明:标准工况下的设备运行参数与实测结果基本符合,验证了数值模拟的准确性;对于不同的热源形式与设备结构,传热效率主要受辐射传热与结构空间几何特性影响,基本符合以下规律:直燃式设备内辐射传热强度较高、所需的物料停留时间较短,而恒温烟气式设备由于热源温度低、辐射传热强度降低,热脱附效果对物料停留时间的依赖性较强;直燃式回转窑受料层运动形式与烟气侧流动传热影响,综合传热系数最高。Abstract: For the unclear mechanism of thermal desorption of petroleum hydrocarbons in soil, a coupling heat transfer simulation model of the soil side and flue gas side was created, and the soil side mass transfer process was simplified into a heat transfer process under variable specific heat conditions. The coupled diffusion flame combustion model, gray gas weighted sum model, and discrete coordinate radiation model were used to simulate the thermal desorption equipment used in China’s domestic industrial applications. The calculation results showed that the operating parameters of the equipment under standard working conditions were basically consistent with the measured results, which verified the accuracy of the numerical simulation. For different heat sources and equipment structures, heat transfer efficiency was mainly affected by radiation heat transfer and spatial geometry characteristics of the structure. Direct-fired equipment had higher radiation heat transfer intensity and shorter material residence time. In contrast, constant temperature flue gas equipment strongly depended on material residence time due to low heat source temperature and reduced radiation heat transfer intensity. The direct-fired rotary kiln was affected by the movement form of the material layer and the heat transfer of the flue gas side flow, and the comprehensive heat transfer coefficient was the highest.
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Key words:
- contaminated soil /
- indirect thermal desorption /
- numerical modeling /
- temperature field
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