Views: 0 Author: Site Editor Publish Time: 2024-03-18 Origin: Site
Scaling in Mechanical Vapor Recompression (MVR) evaporators is a common challenge that can significantly impact efficiency and operational costs. What causes MVR evaporator scaling? and are there any preventive measures to maintain optimal performance?
In MVR evaporators, scaling happens when minerals like calcium, magnesium, and silica, as well as organic compounds, concentrate and solidify on surfaces due to the heat involved in evaporation.
This can lead to decreased efficiency and increased cleaning needs. Pre-treating the input materials to reduce these contaminants can help prevent such scaling, ensuring smoother and more efficient operation of the evaporator system.
For detailed explanation on MVR evaporation process, please view the blog "MVR Evaporator Working Principle".
Implementing pre-film anti-scaling treatment during the manufacturing process. This can form a protective layer on the evaporator and condenser tubes, effectively preventing dirt crystals from adhering to the surface of the copper tubes, reducing the possibility of evaporator scaling, and prolonging the evaporator and air cooler.
Set up a precooler in the evaporator and air cooler to keep the evaporation temperature of the evaporator tube surface below 40°C. At the same time, use a large amount of water and a dense water distributor to ensure that the surface of the condenser tube is always covered with a water film, without any Drier point. Setting up a precooler and preventing the occurrence of dry points can prevent scaling problems in evaporators and air coolers.
Use a small number of continuous drainage devices to control the concentration multiple 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 cooling circulating water of the evaporator, air cooler, and closed cooling tower is a solution to the problem of scaling, and can solve the problem of scale prevention and scaling of the evaporator from the source.
Strictly control the quality of raw materials, eliminate the use of titanium ore with high calcium and magnesium content, and reduce the calcium content in the ore to less than 0.1%.
Switch to a calcium-free filter aid. In addition to small particles, narrow particle size distribution range, and hard particles, the requirements for filter aids must also have good dispersion, good suspension, and good chemical stability. Only in this way can filter aids be used. Finally, a porous filter cake is formed, which is conducive to filtration and improves the filtration effect.
Filter aids commonly used in industry include diatomaceous earth, cellulose, and carbon filter aids. After comparison, we finally chose activated carbon powder. The nearly spherical shape of carbon powder particles is beneficial to filtration and has a certain specific surface area that can adsorb colloids. Impurities. At the same time, it is avoided that calcium-containing filter aids participate in the reaction during filtration and bring in soluble calcium ions.
Maintain the stability of the heating steam, reduce the supersaturation of the material liquid, keep the liquid level stable, and control the material balance; stabilize production and reduce scaling of the evaporator heating tube.
When scaling inevitably occurs in the thin film evaporator, since calcium sulfate is almost insoluble in acid, pickling to remove scale has no effect. Mechanical means have to be used for treatment, which often results in damage to the inner wall of the heating tube, making the inner wall rough and uneven, and making scaling more likely to occur repeatedly during production, thus affecting production and creating a vicious cycle.
According to the principle that calcium sulfate can react with sodium carbonate under heating conditions, the calcium sulfate scale is first converted into a calcium carbonate scale, and then the pickling method is used to remove the scale. This method can easily treat calcium sulfate scale. This method not only reduces the labor intensity of dealing with scaling but also avoids damage to the inner wall of the heater.
By understanding the causes of MVR evaporator scaling and implementing a combination of preventive measures and innovative solutions, industries can enhance the efficiency and longevity of their evaporator systems. Adopting these strategies not only optimizes performance but also contributes to significant operational cost savings. For further consultation, please contact our expert team.
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