Plate heat exchanger is a kind of heat exchanger which is formed by pressing thin metal plates into heat exchange plates with corrugations of a certain shape.It is mainly composed of plates, sealing rubber pads, clamping bolts, compression plates, complete frame and other components. The hot and cold medium flows through the respective channels through adjacent heat exchange plates, and a thin heat exchange plate is used for heat exchange in the middle.Therefore, it has the characteristics of high efficiency, energy saving, high heat exchange coefficient, safe and reliable use, compact structure, small rest area, less floor space, flexible combination, convenient adjustment and maintenance.
Plate heat exchangers can generally be divided into water-water exchange and steam-water exchange. In the water-water exchange method, the hot and cold mediums are all water, and the temperature difference between the cold and hot water is about 70-90 ℃, and the scale is the same on both sides.The heat medium in the steam-water exchange method is steam, which is generally not easy to scale.Scale is mainly due to the fact that various salts dissolved in water are decomposed by heat, the solubility is reduced, and crystals are deposited on the heat transfer sheet.Usually scales such as carbonates, phosphates, sulfates, and silicates are relatively hard and difficult to remove.Dirt is generally composed of fine particles of silt, dust, insoluble salt mud, colloidal hydroxide, debris, corrosion products, oil stains, and algae.This kind of scale is large and easy to remove if it is loose. The cleaning methods of plate heat exchangers are divided into closed circuit cleaning and disassembly immersion cleaning. Before cleaning, scale samples can be analyzed according to the quality of circulating water.