The main sources of waste heat resources
① flue gas;
② high temperature products and slag;
③ cooling medium;
④ combustible waste gas, waste liquid and waste materials;
⑤ waste steam and waste water waste heat;
⑥ chemical reaction.
The typical low-grade waste heat resources
① the flue gas emitted from boilers (heating furnaces) , generally at 140~180℃;
② the slag water of blast furnace slag and steelmaking slag, with the temperature at 60~90℃;
③ the circulating cooling water, mostly at 30~50℃;
④ the extracted water from oil fields, at 30~60℃.
The difficulties of using low-grade waste heat resources
① most low-grade waste heat resources contain corrosive substances, which constitute a considerable impact on the long-term safe operation of equipment;
② some have intermittent characteristics, it's difficult to run continuously;
③ due to the low taste, it is difficult to find a suitable heating (cooling) load near the site;
④ for power generation, the efficiency is low, the technology has yet to mature, the economic benefits are not favaroble.