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一、绪言随着能源问题的日益严重,节能已得到越来越多的重视,工业余热的利用巳提到重要议事日程上来。仅以工业锅炉为例,据统计浙江省共有3000多台,其中大部分锅炉的排烟温度均在250～300℃左右,大量余热未获利用,造成燃料浪费。如能增设余热回收装置,使排烟温度在150℃以下,则将会使锅炉效率提高5～10%,一年节煤是十分可观的。但是,对回收上述低温余热而言,由于热流温度较低,使换热器的对数平均温差极小,所以需要较大的换热面积。对回收相同
I. INTRODUCTION With the worsening of energy problems, energy conservation has received more and more attention. The utilization of industrial waste heat has already been mentioned on the important agenda. Only industrial boilers, for example, according to statistics, Zhejiang Province, a total of more than 3,000 units, most of which are in the exhaust gas boiler temperature about 250 ~ 300 ℃, a large number of waste heat are not used, resulting in fuel waste. If an additional heat recovery device can be installed so that the exhaust gas temperature is below 150 ° C, the boiler efficiency will be increased by 5 to 10%. The annual coal saving is very considerable. However, recovery of the low-temperature waste heat described above requires a large heat exchange area due to the low heat flux and the very small logarithmic mean temperature difference of the heat exchanger. The same for recycling