Diagnosis Methods Based On Tempospacial Energysaving Effect In Large Scale Coal-fired Power Plants

Energy,especially electricity,is undoubtedly the basis and lifeline of the national economy.The share of electricity from thermal power plants has long been over 70% of its total amount.The structure adjustment of power generation industry in the past decade has already confirmed the dominate role oflarge-scale(ultra-)supercritical power plants with higher steam parameters in the near future,whose energy-consumption reaches the world-class level.However,with the increasing consumption of fossil fuel and gradually rigid demand for environment protection,it becomes an urgent demand that the depth energy-saving in large scale coal-fired power plants.Additionally,the “Thirteenth Five Year Plan” of electricity proposed a new target about the coal-consumption and pollutant emission.In this context,researches related to the energy-saving diagnosis in coal-fired power plants will definitely play a key roal for the energy conservation of thermal power plants.The research focuses on the energy system of large scale coal-fired power plants.The energy-saving methods related to the energy system are developed.Additionally,the temporal and spatial characteristics of energy-consumption in thermal power plants are considered,and the concept of tempospacial energy-saving effect is proposed.Based on the concept,a series of researches are conducted.Firstly,the mechanism are studied during the process of components performance degradation;secondly,the energy-consumption interaction are analysed in detailed during operation;then the relation between the energyconsumption of power units with the varying boundaries is described;finally,considering the varying boundaries and pollutant emission demands,the temposapcial energy-saving,obtained from the energy-saving diagnosis,is applied for the plant-level load distribution,which provides an available method for the evaluation,improvement and optimization of large scale coal-fired power plants.First of all,equivalent specific fuel consumption(ESFC)analysis theory,based on the second law of thermodynamics,is improved applying advanced exergy analysis theory.According to the improved theory,component additional specific fuel consumption(ASFC)can be divided to two parts: endogenous ASFC caused by structural factors and exogenous ASFC caused by system factors.The former is caused by the irreversibility of the component itself,while the latter results from those of other components.Thus the special characteristics of power plants can be described through applying the methods of improved ESFC analysis.Additionally,a concept named “Tempospacial energy-saving effect”,aiming to providing reference for the further energy-saving diagnosis,is proposed to quantify the detailed energy consumption state of large scale coal-fired power plants under varying boundaries,which are related to the time-varying circumstance of power plants as well.Secondly,based on the concept of tempospacial energy-saving effect,3 aspects of tasks are studies applying the generation diagnosis methods of energy systems.(1)A component performance diagnosis method based on the improved ESFC analysis is introduced.A newly indicator named internal exergy parameter is proposed to fast and accurately lacate the malfunction components,then improved ESFC analysis method is conducted to compare the endogenous additional fuel consumption between actual and reference state,aiming at qualifying the malfunction effect and further providing reference for malfunction warning or maintanence strategies.(2)Considering the complicated varying boundaries of large scale coal-fired power plants,variable sets with natures of multiple dimensions and completeness are used in order to propose a concept named “energy-consumption benchmark state”,which contains the temporal and special information of coal-fired power plants.Additional,the tempospacial energy-saving effect between actual and benchmark state is calculated and the corresponding reconstruction methods are analyzed to find out available measurements for improvement.(3)The heat transfer characteristics are studied between the coal-fired power plants and complicated varying boundaries(e.g.,load factors,circulating water temperature and coal quality).And the changing principles between the benchmark state and circumstance are calculated when the boundaries are varying.Finally,the tempospacial energy-saving effect is applied during the actual praction and the load dispatching problem is discussed,considering the varying boundaries and pollutant emission of the coal-fired power plants.Based on the operation history data with natures of large volume and completeness,a big data method is introduced to obtain the energy consumption rules under different boundaries and operation conditions.Then the coal consumption rate is forecasted and used for the load dispatching under conditions with varying circulating water temperature.Besides,considering the economic and emission factors,a cyber physical system model is established to obtain the relation between the multiple optimization targets(coal consumption rate and pollutant emission factors)and the information models.Thus,such load dispatching optimization methods can effectively reduce the coal consumed of plants and provide guide for the power grid dispatching.Combined with more practical constraints,the proposed methodology is promising to be applied in the operation diagnosis,system design or retrofits of large-scale coal-fired power plants,in order to reach available operation strategies and improvement proposals.