Research On Cascade Utilization Modes Of Waste Heat In Power Plant

In the support of the national policy of "energy-saving and emission-reduction", using the waste heat rationally, expanding the utilization of waste heat and achieving cascade utilization of waste heat, and increasing the overall efficiency of power plant have become more necessary. On the basis of summarizing the results, based on the theory of the first and second law of thermodynamics, the evaluation benchmark of waste heat resource was proposed; Energy-saving in the model of using waste heat in CHP and CCHP based on the power plant was conducted. Through analysis of this issue, you can draw the following conclusions.Following the principle of rational use of energy, based on the first and second thermodynamics law, the three evaluation method of energy were proposed:energy analysis,exergy analysis and energy level coefficient, meanwhile the theoretical was analyzed, proposed the energy level coefficient was the optimal way of rational use of energy.Compared with the separate generation of heat and power, CHP can be energy saving but not in any case. Energy savings of CHP depends mainly on the energy-efficiency of power generation, heating of energy saving was limited potential. the minimum heat-electricity ratio of the energy-saving was critical condition determining whether or not energy-saving of CHP, Improving the steam parameters of steam turbine admission, reducing extraction parameters of heating steam and improving the thermal network parameters of returned condensed water can reduce the minimum heat-electricity ratio of the energy-saving. The total thermal efficiency represents the effective utilization of fuel of the thermal power plants in the different conditions; there is the best overall thermal efficiency of CHP, and with the minimum heat-electricity ratio of the energy-saving. When the minimum rated extraction is less than the rated capacity of steam extraction, the CHP was energy-efficient and running at the rated capacity of steam extraction was the most energy-efficient, the total thermal efficiency achieved the best value.The energy-efficient of CCHP, was as opposed to the boiler steam driven absorption chiller, but compared with the cogeneration plus electricity-driven refrigeration and separate generation systems, the CCHP with the waste heat of power plant as heat resource can be energy saving but not in any case. From the view of equivalent thermal coefficient, the equivalent power generation efficiency, the equivalent generating coal consumption and the primary energy consumption, the energy-saving of CCHP was studied and proposed the key factors of energy-saving of CCHP-heating steam generating unit parameters, extraction parameters, the performance of refrigeration.With Keng Kou power plant as an example, using the principle of energy cascade utilization, the energy-saving of 1# and 2# heating units were carried out respectively and proposed the key technologies of using waste heat-heat balance, range of heating and characteristics of heat-type chiller.