Drying Technology Status and Development Trends in China (3)

Fourth, development
Drying equipment involves a wide range of fields. In the chemical, pharmaceutical, food, paper, wood, grain and agricultural and sideline products processing, building materials, environmental protection and other fields, drying operations often become the main energy-consuming part of its production process; at the same time, the drying unit to the environment The pollution is also quite serious. Therefore, according to the national "Eleventh Five-Year Plan" requirements, drying technology must go green sustainable development.
(I) Improve the drying process and change the single extensive drying method.
At present, the drying operation of most products in China is completed in a single drying equipment under a drying parameter; and from the drying dynamics of the material, the optimum drying parameters of different materials are different in different drying stages. . If a single drying device and a single drying parameter are used, not only will energy and resources be wasted, but the quality and yield of drying will also be affected. Therefore, it must first be transformed from the drying process.
(II) Conduct comprehensive energy-saving technological transformation to realize the upgrading of equipment.
Comprehensive energy saving should include several aspects of process energy saving, system energy saving, and unit equipment energy saving. Its fundamental purpose is to improve the efficiency of energy use to reduce primary energy consumption and increase the output value of unit energy consumption.
(C) vigorously develop the application of new energy and industrial waste heat drying technology.
To vigorously adjust and optimize the energy structure is one of the major strategic measures for China’s implementation of the medium and long-term energy development plans. China has abundant solar energy resources, biomass energy resources, wind energy and geothermal energy. These are all precious new energy sources. Domestic and foreign experts and scholars have conducted a lot of research work on solar drying technology and achieved certain results, such as the use of solar energy as a heat source to supplement heat has been successful. In addition, advanced energy-saving technologies such as heat pipe technology and heat pump technology can be used to recover waste heat to achieve energy conservation.
V. Trends
(A) Drying Technology Theoretical Study
1. 70s to 2000s in the last century
(1) With the global energy crisis, the main focus of research and application is energy efficiency.
(2) Research focuses on drying dynamics, dryer operation mechanism, and energy efficiency.
(3) With the development of the global economy and the increase in the level of national consumption, research hotspots have begun to shift to the direction of improving the quality of product quality. The main application areas are food and agricultural products.
(4) With the popularization of global computer technology, the research on drying process models and simulations has gradually become hot.
(5) Focus on product quality, but the research hotspot goes deep into the automatic control of the dryer.
(6) Pursuing the overall benefits of the drying process, the professional drying conditions for compound drying conditions, combined dryers, and automatic control operations.
(7) Search for new drying technologies and equipment, and try to revolutionize the drying technology in the drying field.
(8) Develop specialized drying processes and equipment to meet the drying requirements for new materials emerging in the engineering field (eg nanomaterials, biotechnology materials, etc.).
2. Future trends in 2000
(1) Under the impetus of new achievements and new technologies in related disciplines (such as new energy, materials, engineering thermophysics, biology, and computers), the development of new technologies, new energy sources, new processes, and new equipment will be studied.
(2) In-depth modeling, simulation studies (such as the establishment of micro-hole model, multi-phase flow model, CFD simulation, laser detection technology), explore the drying of complex process dryers (such as spray drying, impact flow drying, etc.) Mechanism study.
(3) Under the impetus of research results in basic disciplines, basic research on drying mechanism and drying transfer mechanism is carried out to improve the current situation that the drying process theory lags behind the application.
(4) Combination of special drying objects, optimization of specialized drying processes and equipment theoretical studies.
(5) Research on the degradation mechanism and protective measures of various biological engineering products and food quality indicators in the drying process.
(B) Dry Application Technology Research
The future development of drying technology will focus on the following aspects:
(1) Use superheated steam as a drying medium in a direct dryer;
(2) Intensive use of indirect heating (conduction) drying;
(3) Use of combined heat transfer methods (convection, conduction and heat radiation or dielectric combination);
(4) In special cases, use volumetric heating (microwave or high frequency field);
(5) Combination use of different types of dryers or conventional drying techniques;
(6) Use new or more effective heating methods (such as pulsed combustion, induction heating, etc.);
(7) Use of new gas-solid contact technologies (such as two-dimensional spouted beds, rotating spouted beds, etc.);
(8) Design a flexible, multi-purpose dryer;
(9) Use fuzzy logic, neural networks, expert systems, etc. to achieve control of the process;
(10) On-line measurement of product quality and moisture content.
(11) Large-scale drying equipment develops in the direction of specialization, enlargement, and completeness.
(The author is the Secretary-General and Deputy Secretary-General of the Drying Technology Professional Group of the Chemical Engineering Committee of the China Chemical Industry Society)