Thread Content
Urban sewage and industrial wastewater are excellent low-grade renewable energy sources that can be used as heat and cold sources for waste heat pumps to provide heating and cooling for buildings. Recovering the heat contained in urban sewage and industrial wastewater can replace some coal- and fuel-fired boilers, thereby helping to alleviate environmental problems in our country. Moreover, it can optimize China’s energy structure, alleviate problems of energy shortages and uneven distribution, and is of great significance for energy conservation and emission reduction. Wastewater heat exchangers are key devices for utilizing the heat from urban wastewater. However, as wastewater is of poor water quality, introducing it into heat exchangers inevitably leads to scaling on the heat exchange surfaces, which increases the thermal resistance of these surfaces and causes a rapid decline in the overall heat transfer coefficient of the heat exchanger. Wastewater and debris can even block the heat exchange channels, affecting the continuous and stable heat exchange in the heat exchanger. Therefore, conventional sewage heat exchangers face numerous technical problems such as easy scaling, difficulty in cleaning, and tendency to clog. The existing wastewater heat exchange systems involve filtering the wastewater or industrial waste; a wastewater filtration device is installed before the wastewater heat exchanger, and the filter pores of such a device cannot be too small, otherwise it will become clogged very quickly. Such sewage filtration devices can address the problem of blockages in sewage heat exchangers. However, the small, sticky impurities present in the sewage can pass through these filtration devices and enter the sewage heat exchanger, where they continue to settle inside it and accumulate on the surface of the heat exchange plates, causing scaling. This increases the thermal resistance at the surface of the heat exchange plates, and as a result, the overall performance of the heat exchanger deteriorates rapidly. The wide-channel sewage heat exchanger overcomes the technical problems associated with conventional sewage heat exchangers, such as easy scaling and clogging. It boasts the following technical advantages: 1. The wide-channel sewage heat exchanger is specifically designed for sewage heat exchange; its sewage channels are of the wide-channel type, ensuring good flow conditions within them and reducing the likelihood of clogging. 2. The heat transfer plates of this exchanger are made of stainless steel, which provides high corrosion resistance. Moreover, the surface of these heat transfer plates is inclined and polished, making it difficult for dirt to accumulate or adhere to them. The wastewater flows along the heat exchange surface from top to bottom, with the wastewater behind continuously flushing out that in front, which prevents scaling on the heat exchanger and thus extends its service life while reducing the frequency of cleaning required; 3. The heat exchange between wastewater and clean water takes place through counterflow convection, resulting in a high heat transfer coefficient. 4. During cleaning, clean water flows along the flow channels to flush the heat exchange surface, allowing for cleaning without having to disassemble the heat exchanger. After being in use for a period of time, the wide-channel sewage heat exchanger can be cleaned more thoroughly by opening the manual cleaning port on the side wall of the housing and using high-pressure water for cleaning.