Study On Ash Monitoring And Soot Blowing Optimization System Of Convection And Semi-radiation Heating Surface Of Power Station Boiler

Ash fouling and slagging on the heating surface of coal-fired boiler are unavoidable,which not only affects the heat transfer ability of the heating surface,causes the increase of the exhaust temperature and the decrease of the boiler efficiency,which affects the operation economy of the unit,but also is an important hidden danger for the safe operation of the unit.At present,soot blower is often used in power plants to purge the heating surface for ash removal.However,due to the lack of real-time ash accumulation information of the heating surface and the optimization scheme of soot blowing,most of the operations are carried out in accordance with the schedule and quantity of the team,which makes it difficult to guarantee the economic efficiency and safety of the unit operation.Therefore,the convection and semi-radiation heating surface of the boiler is taken as the research object,and the ash deposition monitoring model of the heating surface is studied to realize the ash deposition monitoring of the heating surface,and then the soot blowing optimization model and the soot blowing strategy are established.Finally,the ash monitoring and soot blowing optimization software system of the heating surface is built,which provides reference and operation guidance for the operators of the power plant.The rate of pollution is used as the heating surface ash monitoring index to indirectly reflect the ash accumulation degree of the heating surface.Based on the heat transfer balance principle of the heating surface,the ash monitoring model of heating surface is built,and the centralized parameter dynamic correction model is introduced to improve the ash monitoring model established under the stable load,so as to realize the ash accumulation monitoring of the convection and semi-radiation heating surface under the full load condition.Taking a 650 MW supercritical boiler unit as the implementation object,collecting relevant thermal parameters for pretreatment and calculating based on the established ash deposition monitoring model,the results show that: under stable load,the pollution rate of heating surface calculated based on the ash monitoring model can accurately reflect the actual ash accumulation of the heating surface;under variable load,the dynamic model of monitoring ash accumulation of the heating surface after considering the improvement of heat storage is more adaptive to the load change and can modify the influence of load change on the pollution rate to a certain extent.Therefore,the ash accumulation monitoring model established in this paper can realize the ash accumulation monitoring of the heating surface under full load condition.According to the results of calculation of ash monitoring model of heating surface,considering the blowing heat transfer of benefit and blowing steam consumption,an optimal soot blowing model with the largest soot blowing benefit per unit time is established.By solving the objective function,the ash fouling time and soot blowing time are calculated,so as to solve the key issue of "when to blow","how long to blow" in the blowing strategy.Based on the soot blowing optimization model,the platen superheater of 650 MW supercritical boiler unit is used as the model heating surface to calculate,and the optimal ash fouling time and soot blowing time are obtained.Compared with the original soot blowing method and another soot blowing optimization model based on the maximum heat transfer in unit time,the optimization effect of the soot blowing optimization model in this paper is verified.At the same time,the effect test of soot blower and the monitoring test of dangerous wall temperature are carried out in the field.The conclusion of the test and the practical operation experience are summarized.The selective input of soot blower,the wall temperature control of dangerous points of superheater and reheater,the temperature control of exhaust gas,the temperature control of main steam,the temperature control of reheat steam and the abnormal operation conditions are analyzed.Then,the consideration is made economic boundary and safety boundary,comprehensive soot blowing strategy with more reference significance to engineering practice.Based on the realization of the monitoring of the ash deposition on the heating surface and the optimization of soot blowing,in Microsoft Visual Studio 2015 development environment,based on B/S architecture,windows application program and web application program are designed and built,and My SQL database management system is used to integrate effective data,so as to build an on-line ash monitoring and soot blowing optimization system platform for boiler convection and semi-radiation heating surface,which has been successfully applied to two 650 MW supercritical boiler units,verifying the feasibility and reliability of the system platform.