Evaporation and its influencing factors and technological developments
Evaporation refers to the vaporization process that occurs on the surface of a liquid, usually referring to the process of vaporizing a part of the solvent in the solution by heating the solution to increase the concentration of non-volatile components in the solution or to cause the solute to precipitate and crystallize from the solution. Generally, the higher the temperature and the larger the exposed area of the liquid level, the faster the evaporation rate. The lower the pressure on the surface of the solution, the faster the evaporation rate; In order to pursue the purpose of high efficiency and low energy consumption, the evaporation equipment is mainly developed in the direction of high heat exchange efficiency, efficient utilization of heat, high heat exchange area and high vacuum, so two types of low-temperature evaporation equipment based on multi-effect evaporation technology and mechanical vapor recompression technology have gradually been formed.
Application of low-temperature evaporation technology
Low-temperature evaporation technology has been more common in our daily production and life, such as seawater desalination, fruit juice concentration, monosodium glutamate manufacturing, etc., and then environmental protection common wastewater salt, cutting fluid reduction, electroplating waste liquid concentration, mother liquor concentration and drying, landfill leachate drying, hazardous waste reduction, etc., which are not only proud of the essential characteristics of evaporation but also proud of the lower and lower operating costs of low-temperature evaporation technology.
Why should you choose the technical direction of low-temperature evaporation?
When talking about evaporation, we can't fail to talk about energy consumption, and it is generally known that evaporation is a large energy consumer in the industrial production process. Especially for the evaporation of water, the specific heat of water and the heat of evaporation are very large, and a large amount of energy is required in both the evaporation preheating stage and the vaporization stage. Theoretically, the evaporation of one ton of wastewater needs to correspond to the consumption of one ton of steam (the cost of fresh steam is between 100-300 yuan), and if the heat loss problem is calculated, the actual amount of steam that needs to be consumed to evaporate one ton of water is 1More than 2 tons. With such high energy consumption, operating costs have become an obstacle to the application of evaporation technology, and if it is not required by the main production process, no company is willing to spend such a large price to do thankless work.
Low-temperature evaporation technology should be an important means to solve the problem of energy consumption at this stage, which integrates a variety of technologies in one to strengthen the evaporation conditions and make the evaporation work can be completed at a relatively low cost.
The principle of low-temperature evaporation is not complicated, in a word, it uses dry air to blow the moisture out of the water.
The process is as follows: the solution is first heated to a certain temperature, and then the solution is passed through the evaporator from top to bottom. The dry air is in full contact with the solution, and in this process the dry air reaches saturation and becomes moist air flowing out of the top of the tower, and the concentration of the solution itself is increased.
A set of low-temperature evaporation system generally includes: preheating (this step is fully automatic, after the original water bucket reaches the medium liquid level, the water pump runs to generate a vacuum, the evaporator automatically feeds the water, and the compressor runs to generate heat to heat the wastewater in the evaporation tank, in the vacuum state, the wastewater temperature rises to about 30, the wastewater begins to evaporate, and the preheating is completed. Evaporation concentration (the evaporation temperature is set to 35-40, the compressor compresses the refrigerant to generate heat, the water evaporates rapidly, the refrigerant absorbs heat after vaporization through the expansion valve and cools, the vapor rises and liquefies the cold liquid into the water storage tank, the refrigerant absorbs the heat, compresses and heats through the compressor, and reheats the wastewater. If bubbles rise during the evaporation process, the sensor detects that the defoamer is automatically added to the defoamer, and after a cycle is completed, the concentrate is discharged (the time of one cycle can be set). Concentrate discharge (After an evaporation cycle is completed, the compression pump stops working, the pneumatic valve of the concentrate pipeline opens, the evaporation tank is pressurized, and the concentration is hydraulically poured into the concentration tank. ）
After understanding the principle of low-temperature evaporation technology and equipment, in order to reduce energy consumption and improve heat utilization rate in the industrial production process to achieve the ideal operating cost requirements, people will combine the aforementioned multi-effect evaporation technology and mechanical vapor recompression technology, vacuum technology, etc., to derive the low-temperature multi-effect evaporation equipment and MVR evaporation equipment commonly used at this stage (please check the above for the difference between the two technologies), which greatly reduces the operating cost of evaporation per ton (taking water as an example, generally ranging from 40-70 yuan). If the operating temperature of the low-temperature evaporation equipment is controlled at 50-60, the heat utilization efficiency will increase, and the evaporation of 80-95 can get more evaporation in the case of the same heat source, and at the same time, as the heat source of the evaporator, some low-grade industrial waste heat can also be selected, compared with the use of fresh steam evaporation, on the one hand, the multi-stage utilization of energy is realized, and on the other hand, the purpose of energy saving and carbon reduction is realized. Even if the energy consumption of the blower and the power consumption of the wastewater cycle are taken into account, the operating cost of the low-temperature evaporation equipment using a low-grade heat source can be well controlled at around 30 yuan tons of water. In addition, due to the low operating temperature of the equipment, it has great advantages in the selection of processing materials, and even some plastic materials are selected instead of metals, so that the processing cost is further optimized.
If it is not a special evaporation requirement, the advantages of low-temperature evaporation technology are incomparable with traditional evaporation technology in terms of production safety, cost input, operating expenses, service life, maintenance, etc., as well as equipment occupation, equipment structure, auxiliary equipment, etc.
4. Weishengda Environmental Protection - the industry's leading low-temperature evaporator provider
In view of the pain and difficulties of high-concentration and high-difficulty wastewater in various industries, Weishengda Environmental Protection took the lead in independently developing 37 low-temperature evaporators, which have the characteristics of skid-mounted, modular, intelligent, no risk of fouling and pipe blockage, no secondary exhaust gas pollution and low residue moisture content. Help customers solve the difficulties such as limited site, low concentration ratio of wastewater, fouling and pipe blockage, and high labor costs, and realize the reduction, recycling, and energy saving of high-concentration liquids stably and efficiently for customers.
Dedicated to R&D and innovation for many years, with more than 150 authorized patents, Wasion can professionally undertake the treatment of industrial high-concentration wastewater such as coal chemical industry, petrochemical, fine chemical, new energy and hazardous waste, with 600+ classic cases in China. Focusing on customer needs, Wasenda can provide customers with customized wastewater treatment services, including working condition investigation, media analysis, pre-sales technical support, R&D and manufacturing, installation and commissioning, delivery, after-sales support and continuous tracking.
Low-temperature steam crystallizer.
Cryogenic heat pump evaporator.
Cryogenic heat pump crystallizers.