Evaporator fouling is harmful. Several common evaporator fouling measures must be

Evaporator fouling is harmful. Several common evaporator fouling measures must be

Evaporator and preheater fouling means that the concentrated salt wastewater contains a large amount of impurity salts, which form crystal nuclei after continuous evaporation and concentration. The crystal nucleus adheres to the inner surface of the heat exchange tube (or surface) and fouls, which will affect the efficiency of the heat exchanger at a minimum, and will block the heat exchange tube, which will seriously affect the normal operation of the evaporation crystallization device. Today, the editor of okmarts.com will teach you how to prevent scaling and how to clean after scaling.

　　 The hazards of evaporator fouling and methods of descaling

The circulating cooling water of the evaporator contains a large amount of salt substances, corrosion products and various microorganisms. Because it has not been treated with water, a large amount of calcium magnesium carbonate scale, algae, and microorganisms will accumulate on the water side after the evaporator runs for a period of time. Mud, sludge, etc., these dirts are firmly attached to the inner surface of the copper pipe, resulting in deterioration of heat transfer, increased circulation pressure, and reduced vacuum of the unit, affecting the operating efficiency of the unit and causing greater economic losses.

　　The traditional cleaning method usually uses chemical cleaning-pickling. This method is effective for various depositions and saves time than mechanical methods. However, chemical cleaning is corrosive to the system and other metal parts, prone to corrosion of equipment pipelines, and pollutes the environment during discharge.

　　 Descaling preparation:

　　 1. Disconnect other systems not related to the evaporator.

2. Open the high-point vent valve on the water side of the evaporator and the low-point pilot valve on the steam side to ensure that a large amount of gas generated during the cleaning process can be discharged in time and the fullness of the cleaning liquid; at the same time, the pilot valve is used to monitor the replacement during the cleaning process Leakage of the copper pipe of the heater.

　　3. In order to monitor the cleaning effect of the system and the corrosion of the equipment during the cleaning process, before the cleaning construction, the standard corrosion test piece and the monitoring pipe section equivalent to the equipment material are respectively suspended in the cleaning tank.

　　 MVR evaporator scale prevention treatment

　　 (1) Pre-film anti-scaling treatment is carried out during the production of the evaporator. Pre-film anti-scaling can form a protective film on the pipe surface of the evaporator and air cooler when making the evaporator, which can effectively prevent dirt crystals from adhering to the surface of the copper pipe, reduce the possibility of evaporator fouling, and extend the evaporator and air cooler. Structure cycle.

(2) A pre-cooler is installed in the evaporator and air cooler to keep the evaporator tube surface evaporating temperature below 40℃. At the same time, a large water volume and dense water distributor is used to ensure that the condenser tube surface is always covered by water film Cover, without drying up. Setting up a pre-cooler and preventing the generation of dry spots have a preventive effect on the scaling problem of the evaporator and air cooler.

　　 (3) A small amount of continuous drainage device is used to control the concentration of calcium ions in the cooling circulating water of the evaporator and air cooler within a certain range to effectively prevent the precipitation of scale. Reducing the calcium ion content of the circulating water of the evaporator, air cooler, and closed cooling tower is the bottom-of-the-bottom strategy to control the scaling problem, which can solve the problem of anti-scaling and scaling of the evaporator from the source.

　　 Wastewater evaporator fouling prevention measures

In the process of evaporation and vaporization of concentrated salt wastewater, it is easy to produce secondary steam mist entrainment. The salt water droplets in the mist adhere to the wire mesh or baffle of the demister, and continuously concentrate and precipitate crystals to form a scale layer. When the secondary steam is blocked.

　　As the concentration of circulating concentrated salt wastewater continues to increase, calcium sulfate, calcium carbonate, and silicate contained in the wastewater will precipitate at the gaps of the distributor of the falling film evaporator, adhere to scale, and cause partial blockage of the distributor.

　　 The control amount of seed crystals in the circulating concentrated salt wastewater in the evaporator is an important monitoring index to prevent the precipitation of the same crystal type and low solubility of the salt from the heat exchange tube (or surface) during the evaporation and crystallization process. Its control range is narrow, easy to fluctuate, and the monitoring and analysis results are lagging. Once the lack of seed crystals is not found in time to adjust, scaling may have occurred.