| The cost and energy consumption of the whole system are increased due to the addition of air separation oxygen production and flue gas compression and purification devices in the oxyfuel combustion coal-fired units.This is also one of the main obstacles to its large-scale engineering application.At present,from the perspective of dynamics and multiple factors,the research on the influence of the change of main operating parameters on the energy consumption of oxyfuel combustion coal-fired generating units has not been carried out in depth.Solar-assisted carbon capture system technology has a good development prospect due to its advantages of energy saving and environmental protection.However,there are few studies on the integrated characteristics of medium-high temperature solar-assisted oxyfuel combustion coal-fired power generation technology.Therefore,this study based on the principle of energy cascade utilization,established the solar and oxyfuel combustion tower coal-fired boiler coupling integration system of physical model,studies the different size,different grade of solar energy and coal chemical energy within the oxyfuel combustion boiler high temperature heat source coupling of different location transfer,thermal power conversion and cascade utilization of law.The advantages and disadvantages of different integration methods are analyzed by means of thermodynamic analysis and solar energy contribution analysis,and the optimal integration scheme is obtained.This study provides an optimal method for the integration scheme of medium and high temperature solar energy and oxyfuel combustion coal-fired units,and provides theoretical guidance and scientific reference for the subsequent studies on the coupling scheme comparison,parameter optimization and system transformation of solar assisted carbon capture plants with different types and capacities.Secondly,this study takes the oxyfuel burning coal unit as the object,selects the main operating parameters such as oxygen purity,oxygen concentration,the proportion of flue gas in the first cycle of boiler flue gas and excess oxygen coefficient as the influencing factors,and takes the system energy consumption index as the experimental target to obtain the dynamic influence of a single operating factor on the thermal characteristics of the unit.At the same time,considering coal price,carbon tax rate,carbon dioxide selling price,carbon emission trading price,interest rate,inflation rate and other factors,the economic model of oxyfuel coal-fired units is established,the influence of operating parameters on the economic performance of oxyfuel coal-fired units is studied,and the economic sensitivity analysis is carried out.Again,in view of the characteristics of oxyfuel coal-fired units energy consumption is affected by many factors,this study based on the orthogonal experiment method and response surface method,with oxyfuel coal-fired units in the boiler thermal efficiency,unit power supply standard coal consumption per unit,unit net electrical efficiency,unit power supply cost,CO2 capture cost indicators such as the evaluation standard,the oxyfuel coal-fired units multi-factor optimization study.The study reveals the dependent relationship between unit energy consumption and several influencing factors.At the same time,the influence degree of each operating factor on energy consumption is obtained through range analysis.The optimal operation parameter combination is obtained through an analysis of variance,which provides theoretical guidance for the optimal design,energy saving transformation and economic operation of oxyfuel combustion unit.In addition,the single-factor and multi-factor analysis based on orthogonal test was carried out by taking the outlet mixture temperature of the pulverizer in the oxyfuel coal-fired generating set as the index of evaluation,and the parameters such as oxygen content in the dry gas,air leakage coefficient,flue gas proportion in the first cycle of flue gas and flue gas preheating temperature as the influencing factors.The influence degree of each factor on the temperature of coal mill outlet mixture and the optimum operating range of each factor are obtained.It provides some theoretical reference and technical guidance for the safety and economic operation of oxyfuel coal-fired units.Finally,based on the principle of equivalent enthalpy drop method and the principle of thermal economics,this study also carried out the scheme design,parameter optimization and economic sensitivity analysis of waste heat utilization system of oxyfuel combustion coal-fired units,and obtained the optimal waste heat utilization scheme.It provides feasible suggestions for the addition of waste heat utilization system for oxyfuel coal-fired units and provides reference for the formulation of subsidy policy for power generation. |
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