Waste Heat Cascade Utilization Research Of Large-scale Cogeneration Units

Energy conservation of urban heating industry has been the focus task of national and local planning. Cogeneration technology achieves a cascade utilization of energy, which is of great significance to the achievement of urban heating energy saving. But for the large capacity heat cogeneration units, due to the high quality of steam extraction, and the existence of large exhaust cold source loss in low-pressure cylinder, resulting in the advantages of energy cascade utilization in cogeneration are not fully tapped. For the current level of 300MW and above large-capacity cogeneration units, this paper puts forward new cogeneration heating system (DCK),which Couples circulating water heating directly connected and heating of steam extraction. DCK takes advantage of the overage heat coming from the low-pressure cylinder exhaust steam, thus reduces the loss of cold source and high-grade steam extraction to achieve efficient use of energy. This article conducts a comprehensive analysis of DCK new system suitability from the heat source, heating network, heat users. After correcting last stage isentropic efficiency curve and adjustable level sliding pressure curve of Ebsilon software, comparison with the simulation results and the thermal equilibrium, the error controls in less than 3 percent. In this paper, Ebsilon software is used for different condition simulation analysis of a 350MW supercritical wet of heating units, put forward equivalent coal consumption rate which is closer to the actual standard to analyze the heat economy, comparing with the DCK model and the traditional heating mode, both the number of heat and power output increase, substantial economic benefits; and detailed analysis the heating load variable condition of the new mode to calculate the turbine operating parameters of the time-varying conditions and waste heat utilization; using two simple heating supply network model to determine the DCK mode optimal proximity distance at different heating loads heating distances of remote users.