UA82757C2 - Dust system of cycling boiler - Google Patents

Abstract

The invention relates to milling solid fuel in ball drum mill, in particular in dust system of cycling boiler. To pipeline for supply of smoke gases from boiler to mill gas-air ejector is installed. Its high-pressure side is connected to air heater of the boiler. Under pressure of hot air from air heater with temperature 350-400 °C gas-air ejector sucks high-temperature gases from boiler, increases pressure of those and supplies additional heat. The invention promotes increase of drying productivity in cycling boilers due to takeoff of inert gases with higher initial temperature, with desaturation of those with hot air and increase of pressure of gas mix before the mill.

Description

The invention relates to thermal power engineering, in particular dust preparation equipment with solid fuel grinding in a ball drum mill and drying with high-temperature inert gases from the boiler, and can be used at thermal power plants.

The dust system of a maneuverable boiler with an air heater, which contains a ball drum mill, is known, the inlet pipe of which is connected by means of pipelines to the selection of high-temperature inert gases from the boiler and the raw coal feeder, and the outlet pipe - with a separator, cyclone and mill fan |Luzin P.M. . etc. Individual open systems! dust preparation of boiler units. M: NIIZINFORMZNERGOMASH, 1979, pp. 20-34).

In the well-known sawdust system, fuel drying is carried out by the heat of high-temperature inert gases taken from the boiler and transported through the mill, separator and cyclone by the mill fan.

However, the known system of dust preparation is characterized by low drying performance due to significant suction of cold air. The inclusion of the mill fan at the end of the technological scheme puts all the elements of the dust preparation path under significant rarefaction, for example, at the place of selection of high-temperature gases for boilers of ZOOMWt blocks, the amount of rarefaction is 200-400Pa, before the mill - 1300-2000Pa, before the mill fan - 4000-6000Pa. At the same time, the intake of cold air into the dust preparation system reaches 50-7095, which is 2-2.5 times higher than the standard value.

In addition, as a result of dilution of high-temperature inert gases with cold air, their temperature in front of the mill decreases by 50-80"С. The drying productivity of the dust preparation system decreases by 15-25965.

Also known is the dust system of a maneuverable boiler with an air heater, which contains a ball drum mill, the inlet pipe of which is connected to a device for increasing the pressure of high-temperature inert gases, for example, a flue, and a raw coal feeder, and the outlet pipe is connected to a separator, a cyclone and a mill fan Unlocked system! piilepreparation. Labor! ЦКТИ, edition of ЯИ, L., 1971, pp. 55-56). The device for increasing the pressure of high-temperature gases (flue) is designed to reduce the rarefaction in front of the mill to the level of 100-200 Pa and to overcome the aerodynamic resistance of the pipeline from the boiler to the mill. A decrease in the amount of rarefaction in the elements of the dust preparation system causes a corresponding decrease in the suction of cold air.

However, the known dust system of a maneuverable boiler is characterized by insufficient drying performance in maneuverable modes, especially when burning non-design fuels with increased humidity. The use of a draft-gas machine (smoke) imposes restrictions on the upper temperature level of inert gases taken from the boiler - under the conditions of reliable operation of the bearings of the smoke, the temperature of the gases should not exceed 400"C, which significantly reduces the drying capabilities of the known dust preparation system. In addition, installation and operation of a draft-air drying machine makes the dust preparation system more expensive.

Also known is the dust system of a maneuvering boiler, which contains a raw coal hopper, which is connected by a pipeline to the inlet pipe of a ball drum mill through a raw coal feeder, to which a pipeline for the supply of high-temperature inert gases from the boiler and a pipeline for the return of undercuts from the separator are also connected to the outlet a separator, a cyclone and a mill fan are sequentially connected to the mill outlet (Patent of Ukraine 73881, Byul. Me9 dated September 15, 2005).

However, the known dust system is also characterized by insufficient drying performance in maneuvering modes due to the lack of regulation of the temperature of the heating agent, which leads to a decrease in the efficiency of the power plant.

The invention is based on the task of increasing drying productivity in maneuverable modes and thus increasing the efficiency of the power plant.

The task is solved by the fact that in the well-known dust system of a maneuvering boiler, which contains a raw coal hopper, which is connected by a pipeline through a raw coal feeder to the inlet pipe of a ball drum mill, to which the pipeline for the supply of high-temperature inert gases and the pipeline for the return of fines from the separator are also connected, a separator, a cyclone and a mill fan are sequentially connected to the outlet of the mill, according to the invention, a gas-air ejector with a regulating body is installed in the pipeline for supplying high-temperature inert gases from the boiler in front of the mill, the high-pressure side of which is connected to the boiler's air heater.

Installing a gas-air ejector allows you to use the pressure of hot air from the air heater to supply high-temperature inert gases from the boiler to the mill, the gas-air ejector removes high-temperature gases from the boiler (up to 1000-1100"), increasing their pressure to a value corresponding to the rarefaction before the mill of 100-200Pa , and adds additional heat contained in hot air with a temperature of 350-400"C; as a result, the drying productivity of the sawdust system in maneuvering modes increases and thereby increases the efficiency of the power plant.

In Fig. the diagram of the proposed saw system of the maneuvering boiler is shown.

The dust system of the maneuvering boiler contains a raw coal hopper 1, which through a raw coal feeder 2 is connected by a pipeline to the inlet pipe 3 of the ball drum mill 4, and also to the inlet pipe C are connected the pipeline for the supply of high-temperature inert gases 5 from the boiler 12 and the pipeline for the return of fines 6 from the separator 9. In the supply pipeline of high-temperature inert gases 5 from the boiler 12, a gas-air ejector 7 with a regulating body 14 is installed, the high-pressure side of which is connected to the semi-heater 13 of the boiler 12. In the gas-air ejector, flue gases are sucked in by the flow of hot air from the air heater 13, the resulting mixture enters the ball drum mill 4. A separator 9, a cyclone 10 and a mill fan 11 are attached to the outlet pipe 8 of the ball drum mill 4.

The raw coal feeder 2 supplies fuel to the mill 4, in which it is ground and dried with a mixture of high-temperature inert gases and hot air. High-temperature inert gases are removed from the boiler 12 using a gas-air ejector 7, in which, due to the energy of hot air from the air heater 13, the pressure of the mixture is increased to a value corresponding to the rarefaction in front of the mill 4 in 100-200Pa. Grinding products and spent drying agent are transported through the mill 4, separator 9 and cyclone 10 by the mill fan 11. Regulation of the supply of inert gases can be carried out by the regulating body 14 of the gas-air ejector 7.

The use of a gas-air ejector 7 with a regulating body 14 as a pressure-increasing device in front of the mill 4 makes it possible to select from the boiler and transport inert gases to air drying without restrictions on the upper temperature level. In addition, the ejector 7 produces a gas-air mixture with a temperature lower than the initial value of the temperature of inert gases, which, when installing the ejector directly near the boiler enclosure, allows the use of inexpensive carbon grades of steel for the manufacture of pipelines in the section of the ejector-mill tract.

An increase in drying performance in the proposed dust preparation system in maneuverable modes compared to known systems is achieved, all other conditions being equal, due to the selection of inert gases with a higher initial temperature and their dilution with hot air.

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Claims (1)

The dust system of the shunting boiler, which contains a raw coal hopper, which is connected by a pipeline to the inlet pipe of the ball drum mill through the raw coal feeder, to which the pipeline for the supply of high-temperature inert gases from the boiler and the pipeline for the return of grinding from the separator are also connected to the outlet pipe of the mill in series separator, cyclone and mill fan, which differs in that a gas-air ejector with a regulating body is installed in the pipeline for supplying high-temperature inert gases from the boiler, the high-pressure side of which is connected to the boiler's air heater.