SU944647A1 - Grinding and drying installation - Google Patents

Description

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The invention relates to the grinding of materials, in particular to grinding installations with a device for drying the material and intermediate dust core, mainly to coal grinding installations of power plants and furnace installations in the construction of building materials, etc.

The known coal-grinding installation with an intermediate dust bin and a device for drying coal with flue gases or hot air coming from the air heater of the boiler unit Q.

The disadvantage of this installation is that in the moisture content of raw coal is more than 10, at which the drying potential taken from the hot air preheater is exhausted, the grinding installation works with reduced productivity with increased specific

energy consumption for grinding and fuel supply is deteriorating.

The closest to the technical essence of the invention is a molar-drying unit containing a feeder, a mixing preheater, a drying device, a vented separator mill with a cyclone dust separator, the dust of which is connected to the bunker, connected by a moisture pump to the mill fan | 2

The disadvantage of the known installation 15 is the negative effect on the furnace mode of the cold-ventilated drying agent that is wetted and filled with combustion products, which is particularly acute when using low-reactive wet fuel, drastically reducing the cost-effectiveness and the possibility of pro-burning. The presence of two generators of hot gases complicates the design and operation of the plant, according to the conditions of preventing water vapor in cold elements, installation, working with the recirculation of the drying and ventilating agent and heating it only in the mixing preheater when the humidity is wet coal, which in practice is never below 7, is impossible. The purpose of the invention is to increase the fuel economy, simplify the design and improve the operating characteristics of the grinding plant. To achieve this goal, in the grinding of a new drying plant containing a feeder, a mixing heater, a drying device, a vented separator mill with a cyclone dust separator, and a bunker connected to the pipeline, a waste pump with a mill fan, the leakage of dust is supplied with a mixer with an air duct .1 depicts the gear milling unit; 2, an abbreviated version of the installation | The installation contains a raw material supply path, including a feed, a tel 1, and a drying device 2 connected to the entrance of the mill 3. The exit of the mill 3 is connected by a pipe with a separator 4 located above the raw material fed into the coarse fractions return and output a pipe that is connected to the cyclone dust separator inlet pipe 5 which has a chute 6 dust with a dust shutter - flasher 7 and a mixer 8 located below the blinker, to which the air duct 9 is connected with a control valve 10. Te A dust bag 6 is inserted into a tightly closed intermediate hopper 11 equipped with a suction suction pipe 12 that is connected to a pipeline connecting the gas outlet of the dust separator 5 with the mill fan 13. The supply path of the mill fan 13 is branched into the mixer heater 14 of the drying and churning fan. agent and dust collector 15.

after mixing, the humidity does not exceed the value specified by the moisture conditions on the cold walls of the bunker, and can be adjusted by changing the position of the valve 10. From the bunker II, the dust-free air is sucked into the exhausted drying duct. a drying device 2. The output of the cleaned gases from the dust collector 15 is in communication with the atmosphere, and the churn of the collected dust is introduced into the bunker. 11 with a dry dust collection, or into a settling tank equipped with a conveyor for feeding the collected dust into the raw fuel path, with wet dust collecting (the last option is not shown). In a simplified version, the output path of the mill fan 13 is connected only to the mixing heater It, after which there is a branch to discharge the excess preheated drying fan-venting agent into the furnace. The raw material supplied by the feeder 1 in the drying device 2 comes into contact with the supplied hot gases, is pre-dried and moves to the mill 3, where it is ground and dried to the desired moisture content of the dust. Under the action of the vacuum created by the mill fan 13, the mill product weighed in the drying and ventilating agent rises through a pipeline into the separator 4 installed above the mill 3, from which the coarse dust that is required to regrind is fed back into the mill and the thin venting agent is carried away into the cyclone dust separator 5, it precipitates, and along the stream, overcoming resistance with its weight, t flashers 7, is lowered into mixer 8, where it mixes with air supply 1m through duct 9 with air, and in The air flow is directed to the bunker 11. Due to the large horizontal cross-sectional area of the bunker, suspended dust is deposited under the action of gravitational force, and the space at the top of the bunker is filled with 50 heated incoming dust of the evacuating agent through line 12. Complemented by suction of air from outside the installation and from the bunker 11, containing dust residues and moisture evaporated from the fuel, the drying and ventilating agent is sucked off by the fan 13 and is fed to the mixing preheater I, mixed with the generator The heated gases are heated by the heater and sent to the drying device 2. Excess drying and ventilating agent Fig. 1) is collected before heating by the telephone 1 and cleaned of dust in the dust collector 15, and then discharged to the atmosphere. The dust captured in the dust collector 15 is sent to the bunker 11 with a dry dust collection, or is fed into the raw fuel path during a wet gas cleaning. In a simplified version (Fig. 2, the entire drying-ventilating agent is heated in the preheater 14, after which its excess is discharged into the furnace. The density is heated In the case of grinding the coal, my aerated dust mixer 8 is 0.510 kg / m, which approximately gives a ratio of 0.5 to 10 kg of coal per one cubic meter of moist air, the majorant estimate of moisture content can be obtained from p accounts for mixing the evaporated moisture of the fuel with the ambient air moisture content of 10 t / kg sucked into the underpressure path of the installation and neglecting the effect of hot gases mixed in the preheater 13. Take the specific suction of air, with a moisture content of 0.15 kg per kilogram of wet coal 0.15 kg / kg (15 equal to Q, kQ kg / kg (about 25 with respect to the supply of the drying agent), find the state content of the mixture at the end of the cycle equal to 0, t kg / kg, 4Tg at atmospheric pressure and 100 C gives the relative humidity of the mixture 88%. To mix the air humidity after the mixer B to the recommended value of 50 g / m, 8 mixer, 3 kg of fresh air per cubic meter of aerated dust, i.e. 0.009 kg of air per kilogram of dust. B. As a result of the preheating of fresh air, due to heat, battery2) eluted with dust, the temperature of the dust decreases less than by, and the air temperature

at the same time it can practically reach the temperature of the dust entering the mixer. Increasing the temperature at the end of the cycle to 120-150 C increases the allowable limit of moisture of the raw fuel, increases the temperature margin to the dew point and intensifies the drying process.

Thus, the proposed installation allows the material to be dried with a moisture content of at least 15 without moisture formation, both in the bunker and in other elements of the installation. Its main scheme is not associated with the technological furnace and, therefore, allows autonomous operation of the installation, regardless of the mode of the technological furnace. This simplifies the design and maintenance of both the grinding plant and the technological furnace, and also eliminates the negative effect of the discharged cold dryer. the ventilating agent; On the furnace mode that raises

efficiency of the firebox. Since only a part of the drying-ventilating agent is cleaned from dust, the dust collector is simplified, dust loss and environmental pollution are reduced. In the variant of discharge of a part of the preheated drying agent into the fire chamber, a dust collector is not needed, the cooling down of the fire chamber is reduced,

the ability to increase the flow of air into the main burners and organize the combustion process with a higher excess air ratio in the area of the main burners, which increases;

flame temperature, improves fuel burning and fusion of liquid slag in furnaces of power boilers, especially when working on low-reactive fuel,.

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Claims (1)

Invention Formula A grinding and drying installation containing a feeder, a mixing heater, a drying device, a ventilated separator mill with a cyclone dust separator, whose dust is connected to a bunker connected to a moisture discharge system with a mill fan, which is so different with the aim of improving economy fuel use.