Excess heat utilization has an enormously potential space and is an effective way for energy-saving and emission-reduction in high power consumption industry fields, such as steel, chemistry, building materials, etc. Sources have it that energy loss in the manufacture process of integrated iron and steel works accounts for approximately 66 percent of the total input, wherein the excess heat occupies more than half of the total power consumption. On temperature basis, excess heat can be categorized into excess heat at a high temperature, an intermediate temperature and a low temperature. With the emphasis on excess heat utilization and perfection of the corresponding techniques, most of the excess heat with higher grade, such as high temperature flue gas and low heating value exhaust gas, has been effectively utilized. However, with regard to the excess heat at a low temperature and of low-grade, large-quantity and difficult reclamation (excess heat with temperature between 70° C.˜250° C.), such as hot water with temperature between 70° C.˜100° C., bled steam with temperature between 70° C.˜105° C., flue gas with temperature between 70° C.˜250° C. and so on, the R&D of the effective utilization technology remains to be accomplished.
An ideal way to utilize the excess heat at a low temperature is to convert it into high temperature heating medium such as useful steam in the manufacture process. The conversion techniques comprise second type of absorption heat pump technology. However, there is a problem of minor temperature rise, i.e., low pressure of the stream produced, for the second type of absorption heat pump circulation technology in prior art.