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Pulverizer In A Coal Fired Boiler

Boilers for steam generation in power plants and process industries using coal as fuel.The proportion of the boiler with coal as fuel outnumbers the combined boiler with all other fuels.Coal is pulverized before the fire to achieve a stable and efficient combustion.Many types of mills are used in boilers of different designers.History of pulverization coal dust is the most efficient way of using coal in a steam generator.The coal is such that about 70% passed through 200 mesh (0.075 mm) suitable soil and 99% through 50 mesh (0.300 mm).A pulverized coal boiler can easily be adapted for other fuels such as gas, if necessary later without much difficulty.But during the planning phase, it isto make it possible for multiple fuel boilers.With pulverization technology, boiler size could be manufactured, built and run much more efficiently.Types of mills mainly there are three types of pulverizer used in industry: the slow speed mills such as ball tube mills, the average speed mills such as bowl, ball and race, are rolling mills in this category, and the third type is the high-speed impact mill.The slow speed and medium speed mills are selected for sub-bituminous coal from anthracite to.The high-speed mills are mainly used for brown coal.The purpose of a pulverizer to a coal-fired boilers to deliver pulverized coal into the boiler, depending on the requirements of the steam generatingtransportation of coal dust from pulverizer to the burners in the boilerin order to remove moisture in the coal to an acceptable level for burning in boilersa high density to remove inorganics from coal during pulverizationof coal particles to the required level of refinement, mesh usually 70% to 200 and classify less than 2% on 50 meshcoal pulverizer output parameters influencing when selecting a coal pulverizer play an important role properties.The hardgrove index, total moisture, have to carry coal input size, performance, refinement and mill direct impact on the mill output.The hardgrove index of coal tells us of the ease with which it can be pulverized.A higher index indicates the hardgrove coal is easier to grind.50 hgi is usually brought to the calculation of the basic capacity of the mill.If the coal hgi higher than 50, the pulverizer is supplied, the output will be higher than base capacity and hgi below 50, the outputbe lower.The total moisture in the coal has a high impact on mill output.The higher the humidity, the lower the output.Higher coal dust fineness increases the return to the mill and the output is reduced.The inlet size of the coal also affects the mill output directly.Mill air flow variations lead to changes in temperature and exit million fineness and capacity.Ball tube mill ball mills are either pressure or suction-type.In the high pressure type, the hot primary air for the drying of coal and used to transport the milled coal in the stove.In this type of leakage in the mill area is high.In the suction type suction device for lifting the milled coal into the furnace of the atomizer is used by a cyclone.The tube mills have a large round drum, with sufficient ball charge, which will be held rotated at about 70% of the speed with which the ball would charge against the inner surface by the centrifugal force.Be filled in this mill the balls on the line again.Normally, the ball mill designer three types of balls used with three different diameters.To reduce the size of these balls, as the mills and consequently have the highest ball size is usually used for recharging.In earlier times, most of the ball mills, a single inlet and outlet, but now designers use both ends of feed coal and also for the completion of a coal dust.The controls are well done, the need to calculate the ball and understand the output from the mill.Ball mills are always preferred to be operated at full capacity because of power consumption for this type of mill is very highat lower loads compared with other species.Ball mills can be run for a very high capacity as 75 tons per hour output for a given coal.Vertical spindle mill there are many different types of vertical mills.Designers are using large steel balls ranging from 2 to 6 or more between two slip rings for pulverizing.There are also other types such as tapered rollers with flat dish, deep dish, etc., where load is applied to the rollers and the shell rotates while pulverizing.This type of mill are generally developed up to 60 tons per hour for a given coal, but there are vertical mills with 90 tons per hour spent.A vertical spindle mill is designed for pressure-and suction-type requirements.Boiler designers use this type of mill for poor quality coal as this type of mill rejects foreign materials such as stones and other materials with high density.The power consumed per ton of coal to the mill floor is only two thirds of the ball mills.However, if the primary air fan power must also be considered in the case of a pressurized mill power consumption is reduced by only about 15%.High speed impact mill this type of mill used a central horizontal axis, which has a number of weapons, and a striker of different types is to pulverize these weapons to the coal strike.High-speed impact mills are mainly used in pulverizing of lignite.Today, all boilers are designers decide to use a spherical or vertical spindle mill coal except for brown coal.When selecting the type of mill boiler designer must clearly understand the coal properties, the entire system is used and the maintenance.Itcan always be seen that, when considered alone, the advantage of the mill, the whole economy is boiler may prove to be different.

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