In the food industry, spray drying equipment is a contradiction. It not only allows food to maintain a good appearance and original nutritional value, but also produces coffee mate, egg yolk powder, milk powder, soup, juice powder and other products. The power consumption is large, the volume is too large, the wall sticking phenomenon is easy to occur, and the one-time investment is big. In the case of national environmental protection pressure and people's demand for food, the spray drying equipment should keep its food industry. There is still more work to be done.
Spray drying equipment can be divided into centrifugal type, pressure type and air flow type according to the structure of the atomizer. Spray-dried foods can be solutions, slurries or pastes, but must be pumpable. Food materials need to be atomized before entering the drying chamber for heat exchange. Since the droplets formed by the spray are very small, this provides a considerable heat exchange area, allowing the evaporation process to proceed quickly.
Sticky wall phenomenon becomes the number one problem
Sticking wall phenomenon is a prominent problem that hinders the normal operation of the spray dryer. Food materials rich in animal fats tend to deposit on the wall of the drying chamber. As time goes by, these food materials will gradually become a source of pollution and endanger food health. Therefore, many spray dryer manufacturers and experts and scholars have explored some solutions to the problem of sticking walls.
They think that because the wall temperature of the spray dryer is too high, the product is sticky, so the drying chamber is changed into a sandwich structure to improve the cooling efficiency; the vibrator, the air hammer and the like are used to separate the sticky material; the air is passed through the tower wall. The tangential direction is introduced into the secondary air cooling tower wall; the bottom of the drying chamber wall is often polished with a cone bottom to reduce the possibility of material retention; other companies have added new technologies for anti-stick sweeping...
Too big to face the problem of placing
Excessive volume is limited by the placement area. With the emphasis on food production conditions, many food companies have built a 300,000 or 100,000 class dust-free purification workshop, but the spray dryer is not bulky in the clean area due to its large size. The part that collects the material will be placed in the clean area and the rest will be placed elsewhere.
In the face of this situation, a spray drying equipment system is required to improve the sealing performance and prevent external environmental pollution.
Material control can be transformed into intelligence
The spray dryer requires a finished product particle size distribution, residual moisture content, bulk density and particle shape to meet precise standards, and the resulting pellets can achieve the desired results. Taking bulk density as an example, bulk density is one of the important characteristics of food during spray drying, and each measure must ensure optimum bulk density during operation. The influence of bulk density is related to powder temperature and humidity, feed temperature, particle size distribution, suction dry air temperature, product discharge temperature, air contact mode, sprayer type and position set in the spray dryer.
To ensure that the bulk density of the raw materials of the food reaches the desired effect, an experienced master is required to sit down. However, with the advent of the intelligent era, if the spray dryer can analyze and judge the required spray temperature and duration according to the humidity, position and particle size of the material, it can greatly reduce the dependence of the equipment on people.
The solution to environmental protection and energy conservation is a top priority
Although spray drying has no dust trouble during the production process, it is easy to generate dust at the product outlet. In addition, the low thermal efficiency of spray drying equipment is an indisputable fact. Generally, the inlet temperature is about 150 ° C ~ 250 ° C, and the outlet temperature after atomization drying is 60 ° C ~ 100 ° C. It can be seen that most of the heat energy has not been utilized.
At present, enterprises have solved the dust problem by configuring a cyclone separator, and configured a waste heat recovery device to solve the problem of low thermal efficiency. However, the results are not satisfactory. It can be seen that the spray drying equipment needs to increase research and development efforts on the road of energy conservation and environmental protection, and continue to move forward.
In summary, the application of spray drying in the food industry not only overcomes the shortcomings of materials being difficult to store, but also preserves the nutritional value of the materials, simplifies the production process, and avoids dust troubles during the drying process. With the in-depth research and development of spray drying technology and equipment, more and more spray drying equipment will appear in the market, and the food industry will accelerate development and have broad prospects.