It is inevitable to use closed cooling tower for the waste sludge low temperature drying

Waste and sewage water after purification treatment will produce a large number of waste sludge which contained 99% water, after the conventional sludge dehydration treatment, the water content will drop to about 80 ~ 85%. With the increase of sewage treatment capacity, the annual output of sludge also increases rapidly. According to the investigation results, nearly 80% of the waste sludge generated by wastewater treatment stations and sewage treatment plants has not been properly reduced and recycled. How to reduce and recycle the waste sludge with large yield and complex composition has become an urgent problem to be solved. Further drying of waste sludge is a very feasible method to reduce the amount of sludge. This kind of pre-dehydrated sludge can be further dried by conventional drying equipment to reduce the amount and facilitate transportation. However, the problems of high energy consumption and low energy efficiency generally exist in current sludge drying equipment. Further drying such pre-dehydrated sludge without secondary waste gas pollution, and how to effectively reduce energy consumption is a technical problem in the field of environmental protection.

At present, the common method of further drying the waste sludge with 80% ~ 85% water content , the most widely used sludge drying process equipment at home and abroad is mainly hot drying technology, including fluidized bed drying, belt drying, horizontal rotating disc drying, paddle drying, vertical disc drying, spray drying and other process equipment. The drying process and equipment should be selected according to the requirements of different waste sludge treatment and disposal projects while comprehensively considering the technology maturity and investment and operation cost. Meanwhile, additional treatment facilities should be added to prevent and control the dust and odor emission generated in the process of sludge drying. At present, the commonly used sludge drying equipment in the market has high energy consumption and generally needs to be used under the condition of heating with waste heat source. If the direct use of common energy (such as natural gas, coal, steam, etc.) is extremely expensive, it is difficult to maintain normal operation. However, most sewage treatment plants have no residual heat source and lack of heat that can be directly recovered and utilized. If conventional heat drying technology is adopted, a large amount of capital will be invested in the construction of heat source and energy consumption, and the cost performance is too low. In addition, the existing sludge drying technology mostly carries out drying treatment with single-performance equipment, while drying the sludge inevitably has the problem of dust and odor emission, if the treatment and prevention facilities are not added, it is bound to cause secondary pollution to the environment.

Heat pump low temperature waste sludge drying treatment system uses the heat pump unit as heat source, don't need any fuel consumption in the process of drying, which can save the costs of transportation and storage of the fuel at the same time, avoid fuel pollution to the environment, in addition, due to the characteristics of high heat pump unit can effect comparing, can reduce more than 30% of the energy consumption, saving energy, safety performance is good. The closed cooling tower is mainly used in the refrigeration cycle in the low-temperature drying system of the heat pump. Through the closed cooling tower, the condensed water can avoid direct contact with fungi and algae in the sewage, and the water evaporation and sewage discharge are less than one third of the open cooling system, making it the preferred equipment for energy conservation and environmental protection.