| Waste heat recovery is an energy-saving projects encouraged greatly supported and promoted by nation. In the "Eleventh Five-Year"period, the specific policies supported by nation effectively promotes the technological progress and industrial development of waste heat recovery. The market prospects of waste heat reuse industry will be even brighter with enhancement of supportive policy by nation in "Twelve Five" period.Low temperature flue gas typically contains impurities such as some corrosive substance and fly ash, the smoke temperature is relatively low resulting in low thermal quality, which directly exerts great impact on implementation and normal operation of utilization plan with waste heat.the generation mechanism and effect factors of low temperature corrosion and fouling in the use process of flue gas waste heat was first introduced in this paper, then measures on prevention of d low-temperature corrosion and fouling were proposed, it played a reference role in the device design and operation of low-temperature flue gas heat recovery. The thermal analysis and economic evaluation of the waste heat recovery device was investigated using heat balance method ,exergy balance and energy level balance method , the basic principles of utilization of waste heat was obtained, it was showed that we should make full use of waste heat not only in quantity but also in quality to make full use of waste heat according to its quality and cascade mode.Experiments on sintering process of a steel mill was carried out, the distribution of waste heat, waste heat utilization and the quantity and quality in the sintering process were obtained. accounting on the non-availability and direct emissions of the flue gas with temperature of 300℃from sintering machine bottom end ,six programs was worked out to recover the waste heat, economic evaluation analysis of the six programs were also calculated to obtain the best and most appropriate program, which could effectively reduce energy consumption and pollutant emissions of the sintering process.According to the characteristics of waste gas heat and the user's demand, a program of mobile heating from vehicle waste heat was proposed. chemical plants oil was heated firstly using high-temperature flue gas , then the generated low-temperature flue gas could heat domestic hot water by way of mobile heating to achieve utilization of waste heat in cascade mode. This program was compared with the traditional scheme (burning fossil fuels), it was showed that program of mobile heating from vehicle waste heat had a great advantage from point of view on emissions such as energy, exergy loss, heat storage capacity and CO2. Phase change materials was chose according to parameters of heat source and the heat user, the efficiency of mobile heating could be optimized further.Owing to small temperature difference and big difficulty of heat exchanger in waste heat use, appropriate heat exchanger was selected to enhance heat transfer, model experiments was carried out on lab of low-temperature flue gas heat utilization. In order to increase the heat transfer area and heat transfer effect, fin type heat exchanger was chose and its heat transfer performance was tested; in order to prevent the generation of low temperature corrosion in heat transfer process, the minimum heat exchanger wall temperature was made to be above dew point temperature of the flue gas by 5 ~ 10℃through water recycling to raise water temperature, the use of waste heat from flue gas was maximized without occurrence of low temperature corrosion, referring to the engineering design and operation of waste heat recovery. |
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