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New developments in the development of small laboratory spray dryers

With the development of society, people pay more and more attention to the quality of food drying products, and put forward higher requirements for food quality. The drying process has a great influence on the quality of food products, and sometimes even plays a decisive role. At present, the dominant hot air drying damages the color, vitamin C and other biologically active substances of food to a greater extent. Therefore, high-tech food drying plays an increasingly important role. In addition to the continuous innovation of high-tech drying methods and methods, some traditional drying methods are also constantly being introduced. The drying technology of vacuum freezing small laboratory spray dryers, the drying technology of adsorption freezing small laboratory spray dryers, the drying technology of microwave small laboratory spray dryers, and the drying technology of infrared heating small laboratory spray dryers are all current The drying technology of the small laboratory spray dryer.

Keywords: microwave drying, freeze drying, infrared heating, drying, energy consumption reduction, combined with the drying technology of the small laboratory spray dryer

1 The development trend of small laboratory spray dryers

1.1 Traditional small laboratory spray dryer

Traditional dryers mainly include chamber dryers, tunnel dryers, drum dryers, drum dryers, belt dryers, tray dryers, paddle dryers, fluidized bed dryers, and spouted beds. Dryer, spray dryer, airflow dryer, etc. In addition, in various industries, such as cereals, fruits and vegetables, petrochemicals, fuels and pigments, food, dairy products and other industries, there are also special small-scale laboratory spray dryers and dryers suitable for their own characteristics. The drying technology of these traditional small laboratory spray dryers has a long development history, is mature and reliable, and has been widely used in countries all over the world. In contrast, traditional dryers have low working efficiency, great damage to dried food, and high energy consumption. Therefore, innovation of small laboratory spray dryers is imperative.

1.2 Development direction of small laboratory spray dryer

At present, the main technological innovation directions of spray dryers in small laboratories worldwide are effective use of energy, improvement of product quality and output, reduction of environmental pollution, safe operation, easy control, and multiple functions. The specific research directions are:

1.1 Design and manufacture a new small laboratory spray dryer or drying process.

1.2 Combine various dryers to complete the drying of a product.

1.3 Avoid or reduce environmental pollution.

1.4 The operation is safer and more reliable.

1.5 Reduce energy consumption in general and reduce equipment manufacturing costs.

For example, in the energy-saving drying of food, the focus is on the development of solar drying, microwave and high-frequency dryers, vacuum-microwave combined new small laboratory spray dryers, and hot-air high-efficiency and energy-saving drying.

2 New development of drying technology of small laboratory spray dryer

2.1 Vacuum freeze-drying technology

Vacuum freeze-drying is to pre-frozen materials containing a large amount of moisture to crystallize free water in the materials and freeze them into solids, and then sublime the ice crystals in the materials under high vacuum conditions. A dry product with a residual water content of about 1% to 4% is obtained. The products produced by the drying technology of the small laboratory spray dryer can keep the shape, color, aroma and taste unchanged to the maximum extent, the nutrients are evenly distributed, and the water rehydration is good.

2.2 Adsorption fluidized freeze drying

In vacuum freeze-drying, the partial pressure of ambient water vapor is maintained by the suction effect of a vacuum pump to reduce the total pressure, and the heat of sublimation is achieved through the heat conduction of the dry layer or ice layer, thermal radiation around the material or microwave heating, etc. accomplish. Due to the application of fluidization technology, the material obtains good heat and mass transfer conditions during the intense mixing and contact with the adsorbent, which is beneficial to the drying process.

2.3 Drying technology of microwave small laboratory spray dryer

Microwave heating is to make the heating object itself become a heating element. The microwave passes through the food from all directions, and the food is heated at the same time. It does not require heat transfer media or convection. The temperature inside and outside the food rises at the same time, and the heating speed is fast and uniform. Only traditional The heating method consumes a fraction of the heat, and can better retain the vitamins in the food and the original color and flavor of the food. At the same time, this technology is very popular in the food industry because there is no internal material that changes its microstructure due to capillary surface tension.

The use of atmospheric microwave drying alone will often lead to local overheating of the food and seriously affect the quality of the product, especially in the later stage of drying. The combination of microwave and hot air drying not only increases the drying speed, but also improves the quality of the dried product. The combination of microwave and other drying methods, that is, microwave-assisted drying is one of the current research and development directions of drying technology for small laboratory spray dryers. For example, microwave vacuum drying is an organic combination of microwave technology and vacuum technology, giving full play to the characteristics of microwave heating fast and uniform, and low water vaporization point under vacuum conditions. Combining microwave heating technology with vacuum drying or other drying methods, many new drying devices have appeared, giving microwave drying new connotation and vitality.

2.4 Drying technology of infrared heating small laboratory spray dryer

Infrared heating transfers heat in a radiant manner. When the heated molecule is irradiated by infrared rays of a certain frequency, that is, the radiation energy spectrum of the radiation source and the molecule of the heated object generate resonance absorption, accelerating the thermal movement inside the molecule, so as to achieve the purpose of heating and heating. . Based on the mechanism of infrared heating, infrared heating drying has the characteristics of fast heating speed, high production efficiency, uniform heating, cleanliness, high product quality, and energy saving. Moreover, the equipment is small in scale, low in investment, and long in life, which makes it widely used in various fields. It is mainly used for food processing in the food industry.