A novel ex-situ thermal desorption method and system for efficient utilization of waste heat cascade

Abstract

The invention discloses a novel ectopic heat desorption method and system for cascaded and efficient utilization of waste heat. The jacketed preheating kiln drives the polluted soil to rotate, and the high-temperature flue gas flows through the jacket space to indirectly preheat the soil to 70-80°C. Send it to the heating kiln; the hot blast stove combines natural gas and 300°C clean air heated by the gas-gas heat exchanger, burns through the burner to generate high-temperature flue gas and sends it to the heating kiln to continue heating the contaminated soil; after heating the soil, After dedusting, the high-temperature exhaust gas carrying volatile / semi-volatile organic pollutants is further burned in the high-temperature oxidation chamber at 900-1000°C to completely oxidize the pollutants; the high-temperature flue gas discharged from the high-temperature oxidation chamber passes through the jacketed preheating kiln Reuse and preheat polluted soil; the 600-700°C flue gas flowing out of the jacketed preheating kiln is passed into the air-gas heat exchanger, and the temperature drops to 500°C after heating the clean air, and then flows into the quenching tower for rapid cooling to 200°C the following. The invention realizes the high-efficiency utilization of the residual heat of the high-temperature flue gas in cascades, and can effectively avoid the discharge of secondary pollutants.

Description

technical field [0001] The invention belongs to the technical field of soil remediation, and in particular relates to a novel ex-situ thermal desorption method and system for efficient utilization of waste heat cascades, which can not only use high-temperature flue gas to indirectly heat and preheat soil in a kiln, but also can heat the soil in a preheated kiln through heat and heat exchange. Fresh air, coupled with a complete exhaust gas treatment process, can achieve the effect of precise energy saving and emission reduction, reduce costs and increase efficiency, and realize the efficient, energy-saving and clean ex-situ thermal desorption repair process for organically polluted sites. Background technique [0002] In recent years, volatile pollutants such as benzene series, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, organic pesticides and pesticides have been detected at high frequency in the industrial pollution sites left and abandoned after the relocation...

AI Technical Summary

Problems solved by technology

Since the development of soil ectopic thermal desorption technology so far, due to the low cost of energy abroad, energy-saving factors have not been considered too much in the application, and there are few related researches, resulting in high energy consumption. Its heat loss is 30% to 60%, which is the main part of heat energy loss in the thermal desorption system, causing great waste. It is urgent to study and propose energy-saving and consumption-reducing schemes for thermal desorption equipment

[0004] At present, the waste heat recovery of thermal desorption equipment mostly adopts the method of hot flue gas backflow, which diverts part of the high-temperature tail gas in the high-temperature oxidation chamber to the preheating kiln to heat the soil and combustion-supporting air. This method will cause dust in the equipment. The higher the content, the higher the pressure of the dust collector

Another type of waste heat recovery device adopts heat exchange method to heat the fresh air in the induced draft fan through the hot exhaust gas. This method does not fully utilize the waste heat, and some heat energy is still lost with the exhaust gas.

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