In many cases, the plate heat exchanger is prone to fouling, which will seriously affect the heat exchange efficiency of the plate heat exchanger. Because plate heat exchangers are mostly heat exchange systems with water as the heat carrier. Since some salts are crystallized from water when the temperature rises, they adhere to the surface of the heat transfer tubes to form scale.Plate heat exchangers are widely used cold-exchange equipment, but large-scale plants are costly to deal with the scaling of heat exchangers every year. If the problem is serious, it will affect the safety production. Therefore, it is necessary to find out the cause and treatment of scaling in time.
According to the mechanism of fouling layer deposition, the scale can be divided into corrosion dirt, particulate dirt, chemical reaction dirt, crystal dirt, solidified dirt and biological dirt.Techniques for preventing fouling of plate heat exchangers should consider the following: (1) prevention of scale formation; (2) prevention of bonding between substances after fouling and deposition on heat transfer surfaces; (3) Deposits are removed from the heat transfer surface.
Considering the design of potential fouling in the design phase of the heat exchanger, the following six aspects should be considered:(1) The heat exchanger is easy to clean and repair (such as plate heat exchanger);(2) The minimum dead zone and low flow rate zone should be taken;(3) After the heat exchange equipment is installed, it is not necessary to disassemble the equipment when cleaning the dirt, that is, it can be cleaned at the work site;(4) The flow velocity distribution in the heat exchanger should be uniform to avoid a large velocity gradient and ensure uniform temperature distribution;(5) Under the premise of ensuring reasonable pressure drop and no corrosion, increasing the flow rate helps to reduce dirt;(6) The effect of heat transfer surface temperature on fouling formation should be considered.