| 原位电阻热脱附土壤升温机制及影响因素 |
| 摘要点击 1800 全文点击 667 投稿时间：2020-01-20 修订日期：2020-02-20 |
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| 中文关键词 原位热脱附 电阻热 土壤修复 升温机制 能耗 影响因素 |
| 英文关键词 in-situ thermal desorption electrical resistance heating soil remediation heating mechanism energy consumption influencing factors |
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| 中文摘要 |
| 探究了原位电阻热脱附技术加热土壤升温机制及影响因素.利用原位电阻热脱附小试设备，研究了电流、加热方式、补水及负压对土壤升温和能耗的影响.结果表明，土壤升温主要通过两种机制：一是电能转化成热能，通电对土壤直接加热使土壤温度升高，该升温机制主要存在于两电极之间的土壤；二是热传导，电极之间土壤温度最高，热量逐渐由高温土壤传导至低温土壤，使电极连线周边土壤温度逐渐升高.加热电流大小，影响土壤升温速度，电流越大，土壤升温越快，单位能耗越低；间歇加热方式与连续加热方式相比，土壤升温速度慢，达到相同温度所需时间长，但单位能耗低，仅是连续加热方式能耗的45.2%；加热过程中需不断向电极附近补充水分，以维持较高电流的持续加热；抽提负压大，土壤热损失多，单位能耗高，抽提负压对抽提管附近土壤温度影响最明显.在实际工程中，宜根据时间、成本和效果等选择合适的工艺条件，以期提高原位电阻热脱附修复污染土壤的效率，降低能耗，缩短工期. |
| 英文摘要 |
| The mechanism and influencing factors of an in-situ thermal remediation using electrical resistance heating were investigated. The effects of electrical current, heating method, rehydration, and negative pressure on soil heating and energy consumption were studied using in-situ electrical resistance heating equipment. The results showed that there were two main mechanisms for soil heating. Firstly, electric energy was converted into heat energy, whereby direct heating of the soil by electricity increased the soil temperature. This mechanism mainly existed in the soil between two electrodes. The second was heat conduction, whereby the soil temperature between the electrodes was the highest, and the heat gradually transferred from the high-temperature soil to the low-temperature soil, such that the temperature of the soil far away from the electrode connection gradually increased. The heating current affected the rate of increase of the soil temperature. The higher the current was, the faster the soil temperature rate of increase was and the lower the unit energy consumption was. Compared with continuous heating, intermittent heating had a slower heating rate and required a longer time to reach the same temperature. However, the energy consumption per unit was low and only 45.2% of that of continuous heating. During the heating process, water should be continuously added to the soil around the electrode to maintain a high current and continuous heating. The negative pressure of extraction was large, the soil heat loss was large, and the unit energy consumption was high. In actual projects, appropriate technological conditions should be selected according to time, cost, and the removal rate as a means of improving the efficiency of the in-situ resistance thermal desorption remediation of contaminated soil, reducing energy consumption, and shortening the time limit. |
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