Study On Sewage Sludge Combination Drying With Superheated Steam And Heat Pipe Waste Heat Utilization Device

With the continuous development of society, industrialization and urbanization continuous to rapidly advance, sewage treatment capacity of sewage treatment plant is increasing, along with the amount of sludge produced is increasing. The sludge with the outstanding characteristics of huge volume, high moisture content as well as contains various pollutants, which increase its treatment difficulty. Consequently, in order to effectively dispose the sludge innocuously, realize minimization sludge production and recycle sludge use, the first step is to reduce the moisture content.Heat pipe is a highly efficient heat transfer components, simple structure, strong control, heat exchanger, high efficiency, power consumption, etc, and heat pipe heat exchanger more and more attention, is a very good prospect heat transfer equipment.In this paper, a sewage sludge combination drying with superheated steam was designed. The test-bed contained steam generating system, mixing drying system, heat pipe heat recovery system and fluid-bed drying system. According to the tests to achieve the purpose of the entire test bed has been the selection and design. Finally, installation and debug was successfully completed.To study the effectiveness of sludge drying, the experiment was set under the temperature of 200℃. Heat pipe-heat exchanger could recycle the waste heat effectively, and the temperature could reach 70℃ after heat exchange. The results showed that moisture content dropped from 81.4% to 20% through the sludge superheated steam drying test-bed. According to the results, a complete set of equipment sludge combination drying with superheated steam was designed and conversation of material and energy during the drying process was calculated. At the same time, the selection of equipment and technological process was introduced specifically.The result is summarized as followed :1. Compared to the traditional drying methods, using superheated steam to dispose the municipal sludge in the first level could solve the disadvantages such as high energy consumption, pollution along with the gas emission, long drying time and low drying efficiency. Besides, the latent heat from the gas emission could provide heat for drying sludge in the second level, which achieved the cascade utilization of energy. Consequently, adopting the joint superheated steam drying method consumed far less energy than the hot-air drying.2. The sludge would be primitively molded and sent to the fluid bed drying facility. By molding, the dust production greatly reduced. Accordingly, the maintenance cost for drying facility reduced greatly.3. The superheated steam have the characteristics of high temperature, high heat enthalpy and strong ability for sterilization. So, the steam could not only be used for drying but also for sterilization. Compared to the traditional hot-air-drying method, the superheated steam drying method could produce the less oxygen or oxygen-free environment, thus reducing the production of toxic gas such as NOx and SOx.