In recent years, plate heat exchangers are characterized by their light weight, small footprint, low investment, high heat exchange efficiency, flexible assembly, and easy scale removal. It will be gradually promoted and used in crafts from all walks of life. However, due to the small cross section of the plate heat exchanger. After scaling, blockage occurs at rest, which reduces the heat exchange efficiency of the plate heat exchanger, thereby affecting the safety of the equipment and the normal use of users. therefore. Solve the cleaning of the plate heat exchanger to prevent the formation of scale. It will become an important issue to ensure safe production and economic operation.
Plate heat exchanger in use. Due to improper operation of water treatment equipment. Water quality control is not up to standard, unqualified demineralized water is injected into the system, so that calcium, magnesium and carbonate in the water will decompose into calcium carbonate and magnesium hydroxide precipitation
Knots on the heated surface of the heat exchanger, forming a hard scale. Due to the poor thermal conductivity of scale, the heat exchange efficiency of the heat exchanger is reduced and the thermal energy is wasted. Thus affecting the effect of heat transfer.
Plate heat exchanger fouling cleaning method
Choice of cleaning agent
The choice of cleaning agent is currently pickling, which includes organic acids and inorganic acids. Organic acids mainly include: oxalic acid, formic acid and so on. Inorganic acids mainly include hydrochloric acid and nitric acid. According to the analysis of heat exchanger fouling and process, material and scale composition:
The heat exchanger has a small circulation area and a complicated internal structure. If the cleaning liquid is precipitated, it is not easy to discharge.
The heat exchanger is made of nickel-titanium alloy, using hydrochloric acid as the cleaning fluid. Idleness will cause strong corrosion to the plates and shorten the service life of the heat exchanger.
Through repeated experiments, it was found that formic acid was the best choice for cleaning solution. Adding buffers and surfactants to the formic acid cleaning solution improves the cleaning effect and reduces the corrosion of the cleaning solution to the plates. The chemical test research on the scale samples shows that formic acid can effectively remove the scale. Through the acid immersion test, it was found that formic acid can effectively remove the scale attached to the plate, and its corrosion effect on the heat exchanger plate is also very small.

Basic principles of removing scale
Solution: acid solution reacts with calcium, magnesium and carbonate scales to produce soluble compounds and dissolve scale.
Peeling effect: acid solution can dissolve oxides on the metal surface. Destroy the combination with scale. As a result, scale adhering to the surface of the metal oxide is peeled off. And fall off.
Gas lift function: After the acid solution reacts with calcium, magnesium and carbonate scale, a large amount of carbon dioxide is produced. Carbon dioxide gas is overflowing. For the insoluble or slow-dissolving scale layer, it has a certain lifting power to make the scale fall off from the heated surface of the heat exchanger.
Loosening effect: For scales containing silicate and sulfate, as the oxides of calcium, magnesium, carbonate and iron dissolve in the acid solution, the remaining scale will become loose, waiting to be washed away by the flowing acid solution .
Measures to prevent fouling of plate heat exchanger
Strictly control the water quality during the operation. The water in the system and the softened water in the softening tank must be subjected to strict water quality tests before they can be injected into the pipe network.
When the new system is put into operation, the heat exchanger should be separated from the system, and after a period of circulation, the heat exchanger should be integrated into the system. In order to avoid impurities in the pipe network into the heat exchanger.
In the entire system, in addition to the irregular cleaning of the dirt filter and the filter, the pipe network should also be kept clean to prevent the heat exchanger from being blocked.