| Based on the analysis of low utilization rate of industrial waste heat as well as the insufficiency of the centralized heating supply, this thesis proposed a new program how to utilize industrial waste heat. In this thesis, using blast furnace slag flushing water waste heat from The Shijiazhuang Iron and Steel Group, heat transfer between heat above and heating circulating water was realized through heat exchanger, at the same time circulating cooling water waste heat from the steel mill exchanged heat with water heating through absorption heat pump. Heat extracted from the above two processes was transferred to the steel mill and new constructed and renovated buildings around the mill, heating area amounting to11million square meters. Blast furnace slag water in heat source water utilized in the program is4000t/h in content,70-80℃in temperature, which can offer8℃as available temperature difference,37MW and heating capacity, which can supply heat for1million square meters heating area. As the circulating cooling water,about25000t/h, water temperature at35～40℃,8℃of available temperature difference, can provide232MW heating capacity, by using of natural gas required by the heating extracting process of the absorption heating pump, the utilization of waste heat is amounting to20340m3/h, which can provide190MW heating capacity, so by using circulating water waste heat, heating area amounting to1million square meters can be heated together.In order to determine the energy using situation of this waste heat heating system, in this paper, three methods----heat balance analysis method, exergy balance analysis method and the thermal economic analysis are used. It is founded that blast furnace slag flushing water residual heat utilization heat rate is86.082%, the exergy efficiency of57.679%, which has the very high heat utilization efficiency; compared with blast furnace slag flushing water residual heat, water circulation thermal efficiency was91.491%,31.726%, the waste heat utilization rate is also high, but slightly lower than that of the flushing slag water waste heat, this is mainly because of the low temperature of waste heat from the circulation water, and substation using indirect heat by circulating water heat user and gas combustion process resulted in a large number of exergy loss. After the economic calculation, obtained the system initial investment of the system is328173800yuan, with a normal annual total profit38601200yuan, as a result, the system investment payback period is8.5years, namely after about8years investment cost can be back, with a high utilization value of waste heat recovery and economic value..In addition, this paper also analyzed and evaluated the environment effect, social impact, emission reduction of this system. It is founded that, this system has the unmatchable advantages compared with the traditional heating mode, as a result it has a considerable market prospect and great potential for development. Of course, the design of the system is not perfect, there are some deficiencies, but the authors believe that through continuous improvement of the system, the application of this technology will be more mature and wider in use. From the above aspects discussed above, this thesis aims at offering some data for the development of this area by the example of heat transfer technology in the steel slag washing water and application of circulating water heat by using absorption heat pump heating technology. |
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