RU2648732C1 - Method for calcining solid fuel in rotating kiln (options) - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method for calcining cement clinker in a rotary kiln containing decarbonization, sintering and bleaching zones when burning solid fuels (options). Method includes crushing of solid fuel-petroleum coke followed by screening, separating the pulverized solid fuel into fractions and feeding the obtained fractions to the calcining zones of the rotary kiln, wherein the fractions are separated into fractions of 1.6–12 mm, 0.08–1.5 mm and 0.05–0.07 mm, which are introduced, respectively, into the layer of the kiln charge of the diffusion area of the decarbonization zone – through the annular elevator, into the layer of the kiln charge of the diffusion area of the decarbonization zone – through the kiln head through a separate channel, and into the sintering zone – through the main burner, or the separation of the crushed solid fuel-petroleum coke into fractions of 1.5–5 mm and 0.04–0.5 mm is carried out, wherein a fraction of 1.5–5 mm is introduced into the layer of kiln charge into the diffusion area of the decarbonization zone, and a fraction of 0.04–0.5 mm between the sintering and bleaching zones above the bed of the kiln charge, followed by a sharp cooling with water and receipt of a white cement clinker.

EFFECT: intensification of the calcination process and increase in the productivity of the kiln and the quality of the cement produced is ensured.

4 cl, 2 dwg

Description

The invention relates to the building materials industry, in particular, to methods for burning solid fuel in a rotary kiln during the firing of cement clinker.

A known method of burning solid powdered fuel by feeding it from the hot end of a rotary kiln to the sintering zone through two nozzles to the beginning and end of the sintering zone, which contributes to the uniform distribution of additional supplied fuel along the length of the furnace (ed. St. USSR No. 529355, IPC F27B 7 / 32, op. September 25, 1976).

The disadvantage of this method is the complexity of its implementation.

There is a method of burning solid fuel by feeding it to the decarbonization zone through a loading device mounted on an annular casing around the furnace body, using inclined nozzles with ladles, which supply additional power, for example, in the form of granulated slag through a chute installed on the body. Additional fuel enters the furnace on the surface of the material being fired, mixing with it and then firing together (Pat. RF No. 2102667, IPC F27B 7/32, op. 20.01.1998).

The disadvantage of this method is the low degree of combustion of the fuel.

Closest to the essential features of the proposed technical solutions is a method of burning pulverized coal in a rotary kiln according to ed. St. USSR No. 879230 (IPC F27B 7/36, op. 07.11.1981).

According to the prototype method, solid fuel - crude crushed coal is dried, ground and divided into fractions to obtain fractions of more than 1 mm, more than 0.08 mm and fractions of less than 0.08 mm, followed by their accumulation in different feed hoppers. When firing cement clinker, the shape, size and intensity of the flare burning are regulated by feeding fuel of different fractional composition. The known invention is directed to reducing specific fuel consumption and improving product quality.

The disadvantage of this method is the low heat transfer rate in the decarbonization zone.

The objective of the invention is to intensify the process of firing cement clinker with increasing furnace productivity and the quality of the resulting cement.

This problem is solved by the proposed method of burning solid fuel in a rotary kiln, including crushing solid fuel with subsequent screening, separation of crushed solid fuel into fractions of more than 1 mm, more than 0.08 mm and less than 0.08 mm and feeding the above fractions into the firing zones of a rotary kiln in which, according to the invention, separation is carried out into fractions of 1.6-12 mm, 0.08-1.5 mm and 0.05-0.07 mm, while a fraction of 1.6-12 mm is introduced through an annular elevator into the calcined layer material of the diffusion region of the decarbonization zone, fraction 0.0 8-1.5 mm - into the layer of calcined material of the diffusion region of the decarbonization zone through the furnace head through a separate channel with the possibility of granules crossing the sintering zone fraction, and the 0.05-0.07 mm fraction into the sintering zone through the main burner.

It is advisable to use petroleum coke as solid fuel.

The supply of a 1.6-12 mm fraction through the annular elevator to the diffusion region of the decarbonization zone increases the temperature in this region by 100-150 ° C and allows to intensify the heat transfer between the raw material and fuel, and the feed of the fraction 0.08-1.5 mm into this the area from the side of the sintering zone forces this process and makes it possible to fully prepare the raw materials for the sintering process and thereby improve its quality.

In the second embodiment, for firing white cement clinker, crushed solid fuel is separated into fractions of 1.5-5 mm and 0.04-0.5 mm, while a fraction of 1.5-5 mm is introduced into the calcined material layer of the diffusion region of the decarbonization zone, and a fraction of 0.04-0.5 mm between the sintering and bleaching zones above the layer of combustible material, followed by rapid cooling with water.

Petroleum coke is also used as solid fuel.

The introduction of a fraction of 1.5-5 mm into the diffusion region of the decarbonization zone, as in the first embodiment, intensifies the heat transfer between the raw material and fuel, and the introduction of a fraction of 0.04-0.5 mm between the sintering and bleaching zones increases the temperature in this region. the area in front of the water cooling zone to 1450-1470 ° C, which ensures high quality of the resulting white clinker.

The use of petroleum coke as a solid fuel with its high reactivity allows many times to increase the intensity of heat transfer between raw material and fuel.

In FIG. 1 shows a schematic diagram of the supply and burning of solid fuel to obtain a cement clinker according to the first embodiment, FIG. 2 is a diagram for obtaining a white cement clinker according to the second embodiment, where

1 - crusher;

2 - rumble;

3 - a hopper of a fraction of 1.6-12 mm (first option) or a fraction of 1.5-5.0 mm (second option);

4 - weight dispenser;

5 - feed line of a fraction of 1.6-12 mm (first option) or a fraction of 1.5-5.0 mm (second option);

6 - ring elevator;

7 - rotary kiln;

8 - diffusion region of the decarbonization zone;

9 - sintering zone;

10 - furnace head;

11 - burner;

12 - hopper fraction of 0.08-1.5 mm (first option) or fraction of 0.04-0.5 mm (second option);

13 - pneumatic screw pump;

14 - feed line of a fraction of 0.08-1.5 mm (first option) or a fraction of 0.04-0.5 mm (second option);

15 - hopper of a jet mill;

16 - jet mill;

17 - bag filter of a jet mill;

18 - hopper fraction 0.05-0.07 mm (first option) or fraction 0.04-0.5 mm (second option);

19 - feed line fraction 0.08-1.5 mm in the furnace;

20 - a separate channel for supplying fractions of 0.08-1.5 mm into the furnace;

21 - feed line fraction 0.05-0.07 mm through the main burner.

22 - feed line fraction 0.04-0.5 mm (second option);

23 - ring elevator (second option);

24 - bleaching zone (second option).

According to the first embodiment, the method is as follows.

Petroleum coke is fed into a hammer mill 1, in which it is crushed to a fraction of 0.08-12 mm, and from it to screen 2, where it is divided into two main types of fractions: 1.6-12 mm and 0.08- 1.5 mm.

The 1.6-12 mm fraction is first fed to the hopper 3, and then through the weighing batcher 4 along the line 5 to the ring elevator 6. The buckets of the ring elevator 6 are connected to the nozzles for supplying petroleum coke to the furnace, therefore, when the furnace rotates, they capture fuel and, when are in the upper position above the furnace body, fuel particles pass into the nozzles and then fall into the high-temperature (1300-1500 ° C) gas stream coming from the sintering zone. In this case, the fuel granules ignite, since a small amount of volatile constituents is released. When ignited, the fuel granules fall into the material layer in the diffusion region of the decarbonization zone, where the temperature can be at the level of 950-1000 ° С. Once in the layer of material, coke burns out intensely. The temperature in the layer rises by 100-150 ° C, the endothermic decomposition reaction of CaCO _{3 is} completed and the raw material enters the sintering zone.

The sieved fine fractions of 0.08-1.5 mm from the screen 2 are sent to the hopper 12, and from it the pneumatic pump 13 along line 14 to the hopper 15 of the jet mill 16.

A fraction of 0.08-1.5 mm from the bag filter 17 is blown into the furnace 7 through line 19 through a separate channel 20, next to the main burner 10. The fuel is blown by compressed air previously heated in the heat exchanger due to the heat of the clinker in the refrigerator. In this case, the injection rate is calculated so that, taking into account the windage of the fuel particles, the latter intersect the sintering zone 9 and fall into the material layer of the diffusion region 8 of the decarbonization zone, where, when burning in the layer, they accelerate the effect of intense decarbonization.

With such preparation, the output of substandard clinker is excluded in the decarbonization zone.

From the jet mill 15, finely dispersed material with a fraction of 0.05-0.07 mm enters the bag filter 17, and from it into the finished product hopper 18 and then through the input unit of petroleum coke (not shown in Fig.) To the combined burner 11.

In the second embodiment, the proposed method is carried out according to a similar scheme (see Fig. 2), but a fraction of 1.5-5.0 mm is introduced into the diffusion region 8 of the decarbonization zone, and a fraction of 0.04-0.5 mm is fed through line 22 through an annular elevator 23 above the layer of raw material in the region between the sintering zone 9 and the bleaching zone 24, which is necessary to maintain the temperature in the sintering zone at the level of 1450-1470 ° C. This creates a strong reducing environment and a high temperature of the clinker at the entrance to the water cooling zone, which allows to obtain a high-quality white clinker.

Thus, the proposed invention allows by feeding and burning crushed solid fuel of various fractional composition in different firing zones of a rotary kiln to intensify the firing process and, as a result, to increase the productivity of the kiln and the quality of the cement obtained.

Claims (4)

1. The method of firing cement clinker in a rotary kiln containing decarbonization and sintering zones during the combustion of solid fuel, comprising crushing solid fuel with subsequent screening, separation of crushed solid fuel into fractions of more than 1.0 mm, more than 0.08 mm and less than 0, 08 mm and feeding the above-mentioned fuel fractions into the aforementioned firing zones of the rotary kiln, characterized in that the solid fuel is divided into fractions of 1.6-12 mm, 0.08-1.5 mm and 0.05-0.07 mm, this fuel fraction of 1.6-12 mm is introduced into the layer of calcined cement blade the diffusion region of the decarbonization zone through the annular elevator, the fuel fraction 0.05-0.07 mm into the sintering zone through the main burner, and the fuel fraction 0.08-1.5 mm into the layer of fired cement clinker in the diffusion region of the decarbonization zone - through the furnace head through a separate channel with the possibility of granules crossing the sintering zone fraction. 2. The method according to p. 1, characterized in that petroleum coke is used as solid fuel. 3. A method of firing cement clinker in a rotary kiln containing decarbonization, sintering and bleaching zones when burning solid fuel, including crushing solid fuel with subsequent screening, separation of crushed solid fuel into fractions of more than 1.0 mm and more than 0.08 mm and feeding the aforementioned fuel fractions in the aforementioned firing zones of a rotary kiln, characterized in that the crushed solid fuel is divided into fractions of 1.5-5 mm and 0.04-0.5 mm, while the fuel fraction of 1.5-5 mm is introduced into the layer fired cement clinker into the diffusion region of the decarbonization zone, and the fuel fraction of 0.04-0.5 mm between the sintering and bleaching zones above the calcined cement clinker layer, followed by its sharp cooling with water and obtaining a white cement clinker. 4. The method according to p. 3, characterized in that petroleum coke is used as solid fuel.

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