Application of Heat Pump in Garbage Disposal Process

I. Overview 1.1 Process Optimization and Energy Saving and Emission Reduction According to the scientific concept of development, domestic waste through recycling by category, comprehensive treatment, recycling of resources is a significant progress of social civilization is an important part of sustainable development. At present, domestic waste is usually through landfill, wetland treatment, incineration, comprehensive factory treatment and the like. Among them, landfill will pollute underground water. If wetland treatment is adopted, there are no natural conditions around the city. Although incineration can generate electricity, utilization rate Too low, burned most of the recyclable resources, but also a waste of resources. The most scientific approach is the classification of integrated processing, so make the best use, turning waste into treasure, to maximize the recovery of renewable resources. In the comprehensive treatment system of municipal solid waste, it is necessary to classify the garbage several times, and at the same time separate the waste liquid waste and the waste slag separately, for example, waste liquid, anaerobic fermentation, high temperature aerobic fermentation, solid-liquid separation , Liquid material evaporation concentration, solid material drying process, can be made of high quality organic fertilizer. Among them, anaerobic fermentation, aerobic fermentation, evaporation and concentration, drying and other processes, must be heated, consume a lot of heat, and evaporation and condensation must also emit large amounts of latent heat of condensation, the need for forced cooling, drying a large part of the link Hot and humid gases, boiler operation produces a large number of high-temperature flue gas, the entire waste treatment plant there are many places with hot and hot spots, if a reasonable heat and combing with hot spots on the supply and demand of heat for quantitative analysis of heat and heat Reasonable match with the hot taste, you can find a huge potential for comprehensive heat recovery. For hot hot spots low quality, high demand hot hot spots, but also for the application of heat pumps to create favorable conditions. 1.2 Heat pump technology application and energy saving Heat pump is a heating device that consumes a small amount of high-grade energy at the expense of converting a large amount of useless low-temperature heat into useful high-temperature heat, just as pumping "heat" pumps . The working process of the heat pump can be compared with the pump. The heat pump consumes a small amount of high-grade energy W, converting a large amount of free heat energy contained in the low-temperature heat source or useless low-temperature waste heat QL in the production process into a high-temperature heat QH that meets user requirements. According to the first law of thermodynamics, QH, QL and W satisfy the following relationship. QH = QL + W (1) where QH is the useful heat energy provided by the heat pump to the user in kW, QL is the free heat energy (environmental heat or industrial waste heat) drawn by the heat pump from the low temperature heat source, kW, W is the heat pump working time High-grade energy consumed, kW. From equation (1), we can see that QH> W, that is, the useful heat generated by the heat pump, is always greater than the high-grade energy consumed. However, when heating with fuel heating, electric heating and the like, the heat energy obtained is generally less than the consumed heat Of the electrical energy or fuel, which is the fundamental difference between heat pumps and ordinary heating devices, but also the most prominent advantages of heat pump heating. Heat pump development to this day, the heating temperature (heat temperature to the user) less than 50 ℃ heat pump has been more mature. As the basic components and refrigerant and refrigeration equipment common, the most widely used. Heat pump heating temperature between 50 ~ 100 ℃, the field of industrial applications is gradually expanding, the relevant components and working fluid system is also being improved. Heat pump temperature greater than 100 ℃, its large-scale application there are more technical problems to be solved, the application areas have yet to be exploited. As long as the need for heat energy occasions, there is a heat pump application opportunities, our basic necessities of life and many products around the production process, and heat are closely related, from this perspective, the development of heat pump space is unlimited. Review the history of the development of heat pumps, heat pump development depends mainly on the speed of the following factors. 1) Energy factors include the price of energy (parity of electricity, coal, oil, gas, etc.) and the abundance of energy. When the price of energy between different reasonable or energy stress, the heat pump has a better development environment. 2) Environmental factors When environmental protection considerations, for other heating methods (such as coal-fired heat) have strict limits, the heat pump has more application space. 3) The technical factors include improving heat pump efficiency through the improvement of heat pump circulation, components and working fluids, simplifying heat pump structure by material technology, reducing heat pump cost, using monitoring and control technology to improve the reliability of heat pump and the ease of operation and maintenance, etc., Compared with other simple heating methods have a more comprehensive competitive advantage. 4) One of the differences between low-temperature heat source heat pump and other simple heating methods is the need for low-temperature heat source. The higher the temperature of the heat source, the more advantageous to improve the performance and application advantages of the heat pump. Sometimes it is possible to have and make the low-temperature heat source and even decide the key factor of the heat pump application. Therefore, by exploiting the advanced technology in relevant fields, It is also an important factor to promote the application and development of heat pump. 5) Development of reference field At present heat pump has been applied to heating, making hot water, drying (wood, food, paper, cotton, wool, cereal, tea, etc.) While cooling and heating, etc.), planting, breeding, artificial greenhouses and other fields. Learn more about the heat in different production processes. And heat pump and process organic combination, for heat pump to expand more applications. 1.3 Waste Heat Treatment Technology comprehensive utilization of waste heat treatment strategy In the integrated treatment of domestic waste, anaerobic fermentation, aerobic fermentation, evaporation and concentration, drying and other processes must be heated, consume a lot of heat, and evaporation of the session must discharge a large amount Of condensation latent heat, the need for forced cooling, drying process produces a lot of hot and humid gas, boiler flue gas to produce a lot of heat, waste treatment plant complex building, showroom and workshop offices and so require central air conditioning, heating in winter, summer Cold, greenhouses need heating in winter, many factories need to supply domestic hot water throughout the day, there are many places throughout the waste treatment plant with hot and hot spots. From the perspective of the comprehensive utilization of energy in the whole system, the strategy of comprehensive utilization of waste heat in the process is formulated: 1) The heat generated in the evaporation and concentration stage is provided to aerobic fermentation, domestic hot water in the park and winter air conditioning in the park. 2) Part of the boiler flue gas heat is provided to the dryer unit, the rest of the winter to provide greenhouse heating, other seasons to generate hot water for sale. This article describes only the evaporation and condensation of comprehensive utilization of waste heat. Second, hot spots and heat consumption point analysis In the production of concentration process, the evaporator condensation cooling water, material condensate, steam condensate, vacuum pump cooling water for the hot spots. Pre-fermentation broth, domestic hot water, air-conditioning system for the hot spots. Third, the heat supply and demand analysis 3.1 The characteristics of heat 3.1.1 Evaporator cooling heat Evaporator cooling Aquatic heat is relatively stable, is the focus of heat recovery object, and the evaporator cooling water is the project must be cooled. 3.1.2 steam condensate boiler steam condensate if the heat is not recycled, it will be in the boiler make-up water re-use, make-up temperature is high, the boiler fuel consumption will be reduced, if it is recycled, the boiler energy consumption will increase, the boiler steam Condensation allows the boiler to be recycled naturally. 3.1.3 Material Condensation Waste Heat As the material condensate is recycled, condensed from the evaporator, and then returned to the pulp pool, pulp and then sent to the fermentation tank heating, fermentation, if the heat recovery, the material temperature decreases, In the fermentation phase to consume the same heat more. Therefore, the heat of material condensate should not be recycled.