The vacuum dryer is an important part of the drying equipment. Although the vacuum dryer has the disadvantage of high cost, due to its excellent work efficiency, overall, the vacuum drying equipment is bound to be able to meet the requirements due to its advanced drying method and wide application range Come to the open market. This point can be seen in the fact that vacuum freeze-drying of traditional Chinese medicine is mainly applied to more expensive medicinal materials at present. Downstream small and medium-sized enterprises are bound to be subject to capital affordability when applying this equipment.
The vacuum drying process is a complex, time-varying, and non-linear industrial process. Drying control is to adjust and control the process parameters that affect the entire drying process.
We know that there are many types of vacuum dryers, such as: special vacuum dryers for protein powder, special vacuum dryers for indigo, special vacuum dryers for baking powder...etc. Wide range of applications, relatively rapid development.
The step-length drying expounds the domestic and foreign development trends of several kinds of vacuum dryers, in order to realize the exchange of information, find out the problems that need to be solved in the development of vacuum dryers, and improve the level of vacuum dryers in my country.
When drying under low pressure, the oxygen content is low, which can prevent the oxidative deterioration of the material to be dried, and can dry flammable and explosive dangerous goods; it can vaporize the moisture in the material at low temperature, and it is easy to dry heat-sensitive materials; it can recover the moisture in the material to be dried. Valuable and useful ingredients; can prevent the discharge of toxic and harmful substances in the dried materials, and can become an environmentally friendly green drying. Because of these advantages, vacuum dryers are more and more widely used.
During the synthesis of many chemical and pharmaceutical products (intermediates or final products), solid particles are suspended in a liquid and need to be separated from the slurry at some stage. First, use mechanical solid-liquid separation equipment, such as filter centrifuges, vacuum (or pressure) filters, settlers, filter presses, and static thickeners, to separate solids from liquids. To select the best type of mechanical separation equipment for a certain process, the vacuum dryer technology is mainly determined by factors such as solid properties, capacity and operation mode.
An important driver of variation in product drying performance is the evaporation temperature of the contained liquid, which depends on the process pressure. Lowering the process pressure and lowering the evaporating temperature can bring many benefits, especially for contact drying. It is not necessary to design an ideal drying system that operates only at the lowest pressure and highest allowable temperature, as this would require large and expensive peripheral equipment.
The system is generally designed as a self-regulating pressure vessel. That is, the condenser and vacuum are adapted to handle high vapor flows at higher pressures, and the pressure decreases as the dry volume decreases.
The development of dryers should also pay attention to energy saving and comprehensive utilization of energy, such as adopting various combined heating methods, transplanting heat pump and heat pipe technology, developing solar dryers, etc.; it is also necessary to develop automatic control technology for dryers to ensure optimal operating conditions. In addition, as human beings attach importance to environmental protection, improving the environmental protection measures of the dryer to reduce the leakage of dust and exhaust gas will also be the direction that needs in-depth research.