The most important gas used in China's boilers is coal

　　Fuel and smoke system42XBoiler Burner

　　The most important gas used in China's boilers is coal.Generally massive boilers and strength station boilers frequently use pulverized coal, so it is necessary to have a pulverized coal grinding system.As proven in the figure, the coal falling via the unique bunker is sent via the coal feeder to the coal mill for grinding.The coal is dried at the identical time throughout the coal grinding process. The drying medium is typically hot air.The cold air is fed into the air preheater by way of the blower, where it absorbs the heat from the exhaust and becomes warm air.Part of the warm air thru the pulverizer after the excessive pressure head into the coal mill, in the coal heating and drying at the same time with the pulverized coal away from the mill, it can be seen that this phase of the hot air as a drying medium, but additionally play a function in conveying pulverized coal, generally called this phase of the hot air predominant wind.In the direct blowing system proven in the figure, the mixture of air and powder comes out of the coal mill and is fed without delay into the burner via the pulverized coal pipe and is sprayed into the furnace with the aid of the burner for combustion.It need to be referred to that in an intermediate silo pulverizing system, a essential wind contains pulverized coal into a pulverized coal separator, the place the pulverized coal is separated from the airflow and saved in the pulverized coal bunker, and an suitable quantity of pulverized coal is furnished to the burner from the pulverized coal bunker by a pulverized coal feeder in accordance to load requirements.It can also be viewed from the determine that every other part of the warm air from the air preheater enters the furnace immediately via the distribution outlet of the burner to provide the air wanted for pulverized coal combustion. This part of the hot air is known as secondary air.42XBoiler Burner

　　Pulverized coal offers off a lot of warmth when burning in the furnace.The internal facet of the furnace is laid with a water-cooling tube wall composed of metallic pipes.However, due to the drawback of the warmth load and the extent of the furnace, the smoke temperature at the outlet of the furnace is usually still high.In order to make use of this high temperature flue gas, the flue is additionally equipped with superheater (divided into various stages), reheater, economizer and air preheater and different heating surface.The flue gas of high temperature flows through these heating surfaces in flip and releases warmness to these heating surfaces by convection, radiation and different warmth switch methods.The exhaust temperature from the air preheater is usually around.At this time, the flue fuel can no longer be reused, it is despatched into the dirt collector for separation, the substantial majority of the fly ash carried with the aid of the flue gasoline is removed, and then with the aid of the brought on fan into the chimney, and subsequently discharged into the atmosphere.42XBoiler Burner

　　Soda system42XBoiler Burner

　　During the whole system of steam generation, the working medium goes thru three heating stages in the boiler.First, the boiler feed water is heated into saturated water, then in turn is heated into saturated steam and superheated steam with a sure superheated temperature.These three methods are commonly performed in the economizer, water wall and superheater heating floor respectively.42XBoiler Burner

　　When the boiler is in operation, after water treatment and deoxygenation, the feed water is boosted with the aid of the feed pump and then passes through the high strain heater and enters the header at the inlet of the economizer.In general, the feedwater is heated into saturated water in the economizer.But clearly specific boilers have exclusive conditions.For example, low-pressure small industrial boilers using solid iron economizers do now not generally warmness the feedwater to saturated water;For medium pressure boilers, it may be required that the working medium at the economizer outlet header has up to saturated steam content;For boilers above subcritical pressure, it may also be required that the working medium of the outlet header of the economizer is unsaturated water with massive underenthalpy.The working medium flows from the economizer outlet header via a conduit into the drum, the place it is forced to float through the feed pump.After getting into the drum, the working medium flows into the water-cooled wall decrease header alongside the descending tube, from which it is dispensed to every water-cooled wall tube (i.e.The drift in this part is maintained by way of the density distinction between the soda combination in the descending tube and the ascending tube.After the soda combination returns to the drum, it is separated by means of the soda separation gadget in the drum. The steam concentrates in the steam house in the higher phase of the drum, while the water enters the water house in the lower part of the drum and starts a new natural circulation flow.For high stress boilers, some water usually evaporates into saturated steam each cycle.42XBoiler Burner

　　After the saturated steam in the drum is separated, it is brought into the superheater thru the conduit for overheating.When the superheated steam is heated to the rated temperature, it is transferred to the turbine for work.The boiler proven has a reheater in the convection flue.The steam from the outlet of the steam turbine high-pressure cylinder is diverted to the reheater for reheating.When the required temperature is reached, the reheated steam is reintroduced thru the reheated steam outlet into the center and low stress cylinders of the turbine for enlargement work.42XBoiler Burner