Dry energy saving technology of agricultural products
Drying is an important unit of agricultural processing, but also the largest unit of energy consumption. Therefore, the study of energy-saving drying technology, agricultural products processing is of great significance. Energy saving is mainly reflected in low coal consumption, low power consumption and equipment, such as one-time investment in many aspects. Combined with my plant over the years of practical experience, to develop a better energy-saving technologies.
Energy efficiency in the process of drying agricultural products should include the improvement of the versatility of the equipment, the improvement of the traditional drying technology, the use of advanced energy-saving and drying equipment, the fundamental purpose is to improve the efficiency of energy use to reduce primary energy consumption and improve the unit to sand output value. Through the development and use of new energy sources, reduce the reliability of traditional fossil fuels. Reduce the temperature of the outlet air; reduce the evaporation load; preheat the liquid; reduce the leakage at the joint; preheat the drying medium with exhaust gas; use the combination of drying; the use of internal heat exchanger; exhaust gas Circulation; change the heat source; dry area insulation, to prevent excessive drying. To use advanced manufacturing technology concepts, such as green manufacturing, intelligent design, parallel design technology to achieve the upgrading of drying equipment.
Improve the versatility of the equipment, and enhance the utilization of equipment, reduce duplication of investment and depreciation of equipment by strengthening the development and utilization of versatile equipment, which is highlighted in the food drying. China's drying equipment, the degree of generalization is relatively low, restricting the use of drying equipment, equipment has caused repeated investment.
Because of the wide variety of grain, the harvest period of various crops is different, and its drying process is also different, so through the traditional downstream, mixed flow and other drying process adjustment, so that the existing equipment is a multi-purpose food The main contents of the drying equipment.
The improvement of traditional drying technology, from the combination of drying and equipment improvement and other aspects of the traditional drying technology to optimize the design, significantly improve the efficiency of the dryer or reduce the power of the fan, so as to achieve the purpose of reducing the effective consumption. Combined drying technology, in the process of agricultural products, due to the diversity of materials and the complexity of its nature, sometimes with a single form of dryers to dry materials, often fail to meet the quality requirements of the final product, or meet the quality requirements, But the energy consumption is too great. For this purpose, the combination of two or more forms of dryers can achieve the purpose of a single drying can not be achieved, this drying method known as the group of dry. Combined drying can better control the entire drying process while saving energy, especially for heat-sensitive materials. Combined drying is the focus of research on the current agricultural products. From the current situation, it can be divided into the following methods:
(1) multi-stage series drying in the same drying mode: This method is mainly used in the case of hot air drying. Such as spray drying and fluidized bed drying in the drying of foodstuffs, pharmaceuticals and light industry products, multi-stage combination of air drying and air drying, air drying and swirling flash drying combinations, spray drying and flash drying Combination and so on.
(2) the combination of different heat transfer drying method: This combination of materials in different drying stages of the drying characteristics, give full play to the characteristics of different heat transfer drying, to meet both production needs, but also reduce the cost of production purposes. Such as in the low-moisture rice drying stage using hot air drying and far infrared drying combined. In the economic crops such as wolfberry, raisins, dehydrated vegetables in the drying of the widely used solar drying and hot air drying combined, microwave drying and hot air drying combined, microwave drying and vacuum drying composition of microwave vacuum drying and so on.
(3) Energy-saving and drying process: According to the drying characteristics of agricultural products, different hot air temperatures are used at different stages, such as low-temperature drying, high-temperature drying + slow-drying + cooling of grain for dryness in food Process.
(4) other combinations: As a result of individual agricultural products processing, in the drying of Chang water is very high, the use of mechanical way off a lot of water, and then supplemented by hot air drying. The combination of mechanical and hot air drying has become a popular drying method, such as the use of spiral extrusion in the dry distillation of distillate + flash drying + fluidized drying, starch processing centrifugal dehydration + air drying, in addition to the commonly used mechanical dehydration There are also plate and frame pressure filter, belt filter and so on.
In addition, China's northern corn dry in the use of large-scale fruit and vegetable drying that is used to exchange ventilation and drying process. The main features of the dryer are: (1) single drying large precipitation, such as dry rapeseed can be reduced from 65% to 8%; (2) dryer energy consumption is low, energy-saving effect is significant; as the process of all the secondary Drying section of the high-temperature exhaust powder containing fly powder, by regulating the dry part of the hot air temperature and air volume, can ensure that the non-stick wall under the premise of the exhaust to low temperature (40 ± 2) ℃ high temperature (90%), so that the exhaust Take away the damp heat is significantly reduced. After the test proved that the machine evaporates 1kg of water steam consumption (1.3 ± 0.2) kg, faster than the average air drying speed.
Energy-saving technology in the drying of agricultural products has a wide range of applications, energy-saving technology directly for the performance of consumption savings, energy-saving technology directly reflects the level of application of a country's comprehensive technical level. Energy-saving technology should be a comprehensive concept, not just heat and energy savings. A number of successful practices have shown that the application of energy-saving technologies in the drying of agricultural products can improve the use of conventional drying methods such as combined drying, fan position change, fan pressure adjustment by increasing equipment utilization, reducing duplication of investment and equipment depreciation , The use of energy-saving drying process such as commutation ventilation, positive and negative pressure combined, waste heat recovery, and the use of new energy and other ways to achieve. At the same time, in addition to the use of economic and industry standards, gradually out of some backward equipment, should increase the development of advanced energy-saving drying equipment, technology investment and promotion efforts, attention to dry basic theoretical research, accelerate the introduction of other areas of scientific research.