The Study Of Operation Characteristics Of Coal-fired Boilers On Conditions Of Flue Gas Recirculation

With the rapid development of the national economy,China's energy demand,especially electricity,is also increasing.China's energy structure determines that the coal-based energy pattern will exist for a long time.Coal-fired power plants are still the main power plants in power construction in China.In 2012,the standard of atmospheric pollutant emission from thermal power plants?GB13223-2011?mentioned the existing fires in key areas.Special emission limits are required for generating units.The dust emission standard is 20 mg/Nm³,the SO₂ emission standard is 50 mg/Nm³,and the NO_x emission standard is 100 mg/Nm³.The Pollution emission control is still an important subject in the field of thermal power.Before the new environmental protection standard was issued in July 2014,most thermal power plants had achieved the purpose of controlling NO_x emissions by means of low nitrogen burner transformation and increasing reducing agent input.In some power plants,due to the AGC mode of mixed combustion,there are more operating units of pulverizing system.When the unit is running at low load,the xygen content in the furnace is more adequate,and the value of nitrogen xide at the outlet of the furnace is higher.The large amount of reducing agent will increase the discharge pressure of the power plant and affect the normal operation of the power plant,so it is particularly urgent to reduce the NO_x content at the outlet when the boiler is under low load.In order to solve the above problems,a mathematical model for numerical simulation of 2×330 MW subcritical coal-fired unit in a thermal power limited company is established by means of numerical simulation software Fluent.At the same time,the combustion in the furnace is simulated,and the velocity field,temperature field and the distribution of combustion components in the furnace are compared and analyzed.At the same time,the thermal calculation method is coupled to study the recirculation of flue gas in primary air.The results are compared and analyzed,and the influence of flue gas on boiler operation characteristics is obtained.Finally,the relevant calculation of pulverizing system checking is completed.