SU879230A1 - Method of burning coal dust fuel in rotary furnace - Google Patents

Description

Union of Soviet

Socialist

Republics

State Committee

USSR for inventions and discoveries

DESCRIPTION OF THE INVENTION TO COPYRIGHT CERTIFICATE (61) Additional to ed. certificate-wu - (22) Declared on 02.25.80 (21) 2887420 / 29-33 with the addition of application No. - · (23) Priority - (43) Published on 07.11.81. Bulletin No. 41 (45) Date of publication of the description 07.11.81 (1) 879230 (51) M. Cl. ^thirteen

F 27B 7/36 (53) UDC 666.94.041 (088.8) (72) Author of the invention (71) Applicant

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Yu. A. Ushakov /

Siberian Research and Design Institute of the Cement Industry / ------- (54) METHOD FOR BURNING DUST COAL FUEL IN ROTARY FURNACE

The method relates to the field of preparation and combustion of pulverized coal in rotary kilns and can be used in the construction materials industry and other technical fields.

A known method of burning pulverized coal in a rotary kiln, including drying and grinding coal, separating the finished powder from the drying agent and accumulating it in consumable bins, dispensing coal powder with subsequent blowing it into the combustion space and burning in a torch [1].

The disadvantage of this method is the limited ability to control the size and intensity of combustion of the torch when using simple in design and reliable in operation burner devices.

The aim of the invention is to reduce specific fuel consumption and improve product quality.

The goal is achieved by the fact that in the method of burning pulverized coal in a rotary kiln, including drying and grinding coal, separating the finished powder from the drying agent and accumulating it in consumables, dispensing the coal powder, followed by blowing it into the furnace space and burning it in fa2 the coal powder in the process of separation from the drying agent is divided into fractions by size and accumulated in different feed hoppers, and the combustion is regulated by changing the ratio in the fuel blown into the furnace anstvo coarse and fine fractions.

The method is as follows.

Crude crushed raw coal is fed to the grinding unit, where it is milled and dried using a drying agent - gas from the combustion of fuel diluted with air. From the milling plant, coal powder 15 is aerated, passes through a separator where the grains are separated, and the finished powder with a fraction content larger than 1 mm and not exceeding 1-3% enters the cyclone group to separate the coal powder from the drying agent. The cyclone unit has at least two groups of series-connected cyclones. In the first group of cyclones, a large fraction is separated, for example, a larger fraction

80 microns. The efficiency of this group may be low - 50-70%. A large fraction of the powder from the first group of cyclones enters the hopper for a large fraction.

From the first group of cyclones, aerosol 30 enters the second group, where from dryers3

879230 agent, the remaining part of the powder is separated - the smallest, in this case finer than 80 microns. The efficiency of the second group of cyclones should be high. The fine fraction of coal powder from the second group of cyclones enters the hopper for fine powder.

When the hoppers for coarse and fine powder are full, both groups of cyclones begin to work in a common feed hopper.

Regulation of the torch is as follows.

When the furnace is ignited, while the furnace is still cold, coal is produced from a fine powder hopper. Moreover, despite the “cold” zone, intensive and complete combustion of the coal powder is ensured, since the ignition temperature of the fine fractions of the powder is relatively low. As the furnace heats up, powder is mixed from the middle hopper to the nozzle fuel and then switched to power only from the middle hopper. Further, during the operation of the furnace, when a situation arises requiring to extend the combustion zone, stretch the torch, coal powder is mixed from the coarse hopper to the nozzle fuel. The enlargement of the composition of the nozzle fuel increases the ignition temperature, the combustion mode switches to the “far” zone, in addition, due to the enlargement of the particles, their burning time increases, which at an unchanged speed of the particles stretches the torch, transferring it to the combustion regime of the so-called long torch.

In the opposite situation, reduce or exclude the supply of coarse powder and increase the flow of fine fractions.

The method allows the use of automatic regulation, including the use of electronic computers.

Example. To heat a rotary kiln with a size of 5X185 m, a mixture of total and gas coal is used with maintaining about 25% of volatile components in the mixture. The mixture after the separator contains particles larger than 1 mm, not more than 1%. A powder with a fractional composition of 100% above 80 μm is accumulated in the hopper for a large fraction. Powder with a fractional composition of 100% less than 80 microns is accumulated in the hopper for a fine fraction. In the feed hopper for total coal, the fractional composition is as follows: more than 1000 microns - 1%; less than 1000 microns - more than 80 microns - 16% and less than 80 microns - 83%.

With a weakening of the degree of heat treatment of the material in the preparation zones of the furnace and the approach to the sintering zone of the thermally unprepared material in the nozzle fuel, the content of the fraction of finer 80 μm is increased to, for example, 95%. This process intensifies the process of fuel combustion, the temperature in the sintering zone and the reject yield increase excluded.

In the opposite situation, when the temperature in the sintering zone increases excessively and decreases in the preparation zones or remains at the same level, which can occur, for example, with an increase in sludge moisture, the content of fraction 0 in the nozzle fuel is larger than 80 μm to, for example, 28 % After restoration of the normal mode, they switch to the average fractional composition of coal.

In all cases, fuel consumption and the total heat input to the furnace remain unchanged5.

Using the method will effectively affect the shape, size and intensity of the torch burning, reduce the time required to enter the furnace into the mode when it is violated, which will reduce the yield of defective material, increase the quality of clinker and reduce specific fuel consumption.

Claims (1)

Claim A method of burning pulverized coal fuel in a rotary kiln, including drying and grinding coal, separating the finished powder from the drying agent and accumulating it in the E feed hoppers, dispensing the coal powder, followed by blowing it into the furnace space and burning in a torch, characterized in that, for the purpose reducing specific fuel consumption and improving product quality, the finished coal powder in the process of separation from the drying agent is divided by size into fractions and accumulated in different feed bins, and evidence of a change in the ratio of coarse and fine fractions in the fuel injected into the furnace space. Sources and 11 forms of technology and qi,> taken into account during the examination 1. Boganov A. I. Rotary kilns of the cement industry. M., Mechanical Engineering, 1965, p. 18-20, FIG. 1 (prototype). NGO “Search: Order 1891/17 Edition number 589 Circulation 694 Subscription Printing house, 2 Sapunova ave.