Disadvantages of sewage source heat pump?

Sewage source heat pump is a type of water source heat pump. Water source heat pump is a low-grade thermal energy resource formed by utilizing shallow water sources on the earth's surface, such as solar energy and geothermal energy absorbed in groundwater, rivers and lakes. It uses the heat pump principle to realize the transfer of low-level thermal energy to high-level thermal energy through a small amount of high-level electrical energy input. a technology.
Disadvantages of sewage source heat pump?
What are the types of sewage source heat pumps? There are many types of sewage source heat pumps. Depending on whether the heat pump directly extracts heat from sewage, it can be divided into two types: direct type and indirect type. The so-called indirect sewage source heat pump means that there is an intermediate heat exchanger between the low-level heat source loop of the heat pump and the sewage heat extraction loop, or the low-level heat source loop of the heat pump directly absorbs sewage in the sewage pool through a water/sewage immersed heat exchanger. of heat. The direct sewage source is that urban sewage can be directly placed in the sewage pool through a heat pump or the evaporator of the heat pump, and the heat in the sewage is absorbed through the refrigerant gasification.

The particularity of sewage and its impact on sewage source heat pumps Editor:

Urban sewage consists of domestic sewage and industrial wastewater, and its composition is extremely complex. Therefore, sewage source heat pumps often have the following problems:
(1) When sewage flows through pipelines and equipment (heat exchange equipment, water pumps, etc.), scaling is prone to occur on the heat exchange surface, microorganisms attach and grow to form biofilms, and the oil in the sewage adheres to the heat exchange surface to form an oil film and float. Solids and suspended solids block the inlets of pipes and equipment. The result is a blockage of the sewage flow and a deterioration of the heat transfer process due to an increase in thermal resistance.
(2) Sewage causes corrosion problems in pipelines and equipment, especially hydrogen sulfide in sewage, which causes corrosion and rust in pipelines and equipment.
(3) Due to the blockage of sewage flow, the flow resistance of the heat exchange equipment continues to increase, causing a continuous decrease in the amount of sewage. At the same time, the continuous increase in heat transfer resistance causes a continuous decrease in the heat transfer coefficient. Based on this, the operation stability of sewage source heat pump is poor, and its heat supply decreases with the extension of operation time.
(4) Due to the flow obstruction of sewage and the attenuation of heat exchange, the operation, management and maintenance workload of the sewage source heat pump is heavy. For example, in order to improve the operating characteristics of the sewage source heat pump, the heat exchange surface needs to be hydraulically flushed 3 to 6 times a day. Second-rate.