Modular Computing Platform Development And Application Of Thermal Power Plant Equipment And Systems

With the gradual expansion and increasing competition of the electricity market,the plant should not be satisfied merely to maintain the normal operation of the unit,but also make the unit operate in the most stable and economical state.The performance calculation and economic analysis of thermal system play an important role in reducing coal consumption and improving operational efficiency of power plants.Existing thermal system calculation softwares mostly design for a particular type of unit,have poor versatility and scalability.After analyzing the pros and cons of existing calculation softwares,we develop a "Caling" computing platform using C#language.The platform uses graphical modules to build models,the models can be calculated while building,and the calculation results can be displayed in real time and output in graphical or tabular form.The mould library and its function is open,the user can customize the additions and modifications to meet the computing needs of new field,new technology and new equipment.Using the Caling platform,this paper mainly carried out the following work:First,according to thermodynamic calculation criteria and methods,choose the appropriate way to write functions such as boiler heat balance,fuel properties,fluid physical properties,auxiliary classes,furnace emissivity,temperature difference and coefficient of heat transfer,to construct radiation heating surface,convection heating surface,regenerative heater and other equipment moulds.Second,use Caling platform to analyze and forecast boiler operation.Build a 130t/h coal-fired boiler model as an example,and then design the structure of the heating surface according to design requirements.While designing,the optimal enthalpy growth of high temperature superheater and the two-stage layout principle of economizer and air preheater are took into account.Check calculation introduces a process-based heat transfer calculation method,brings in the heat capacity of metal to make the model converge easier.If the checking error is bigger than allowable value,the model will adjust the structural parameters and recalculate automatically.The main idea of the process-based heat transfer calculation method is that a thermal fluid first heats the wall,then the wall heats the cold fluid,outlet temperature of flue gas and working fluid iterate from temperature of 0 degrees without assumptions and logical judgments,conforming the actual situation of heat transfer process,so that it can be used to simulate boiler operation.Therefore,after completing boiler check,the model is used to simulate boiler operating in different conditions.In this paper,the model is used to study the change of outlet gas temperature,boiler efficiency and economizer outlet water temperature under different load,coal and water temperature.The analysis of boiler operating characteristics under variable operating conditions has a good reference value to guide boiler improvement and optimize boiler operation.Third,according to the needs of a design company,use Caling platform to analyze and study thermal system without deaerator.The system is 300MW unit with steam feed pump,has three high pressure heater,four low pressure heater and one deaerator.Learning from the former Soviet Union using mixing heater to deoxidize,we transform the system by cancelling its deaerater,adding a surface heater as the number 4 LP heater,and adding a mixing heater after condensate pump,the exhaust steam of small steam turbine,drain of the last LP heater and seal heater are introduced into the mixing heater so that the condensation water can be heated to saturation temperature to remove oxygen.Six transformation programs for the system are proposed and corresponding models are built.Use conventional heat balance method and variable condition calculation method,calculate thermal economic indicators such as relative internal efficiency,steam consumption,heat consumption,the whole plant coal consumption rate and thermal efficiency,analyze the impacts of transformations on thermal economy.The enthalpy of small turbine exhaust steam is found haven't fully utilized when checking,so adjust the exhaust pressure and calculate corresponding thermal economic indicators until the optimal pressure is found.Through comparing the advantages and disadvantages of transformation programs,provide calculation basis for the selection of thermal system without deaerator.