JPH10279959A - Coal gasifier - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent clogging due to slag adhesion in a cooling furnace and secure high slag collection efficiency in a coal gasifier. [MEANS FOR SOLVING PROBLEMS] By providing a projection on a ceiling portion of a gasification furnace, even if the gasification furnace burner has a strong turning force, the gasification burner entering the throat portion is attenuated.
The molten slag adhering to the furnace wall of the throat can be transferred to the gasification furnace, and the molten slag that has accumulated at the lower part of the throat becomes molten slag having a diameter of several mm and scatters in the cooling furnace. Can be prevented from clogging, and the slag collection efficiency in the gasification furnace can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for gasifying pulverized coal, pulverized char and the like in a spouted bed using an oxidizing agent.

[0002]

2. Description of the Related Art A method of converting coal into pulverized coal and gasifying it in a spouted bed gasifier is excellent in that high thermal efficiency and gasification efficiency can be obtained. As shown in FIG. 5, this gasification method which has been practically used in a conventional gasification method includes a gasification furnace 1, a burner 3, a throat 2, a slag tap 4, a cooling furnace 5, and a cooling water tank 6. In this method, pulverized coal and an oxidizing agent are ejected from the burner 3, and the pulverized coal and the oxidizing agent are reacted in the gasification furnace 1 at about 1500 ° C. to gasify.

The generated high-temperature gas is discharged from the upper part of the gasification furnace through the throat 2 and cooled in the cooling furnace 3 to a temperature at which ash in the coal is solidified, that is, about 1000 to 1200 ° C. After heat recovery and removal of harmful substances, it is used as fuel or chemical raw material gas. Most of the ash in coal is
After melting with high-temperature gas and accumulating at the bottom of the gasification furnace, it is discharged from the slag tap 4 as slag and cooled and solidified in the cooling water tank 4, but a part of the cooling furnace is accompanied by the gasification gas. Splashes into 3. The gas furnace 1 includes a ceiling 9, a cylindrical side wall 10, and a bottom 11, and is usually made of steel. However, the furnace wall of the ceiling 9, the side wall 10, and the bottom 11 of the gasification furnace 1 has a water-cooled jacket or an outer surface. , A cooling structure provided with a cooling pipe. In general, the inner surface that comes into contact with the gas is protected by self-lining with molten slag. The ceiling 9 of the gasification furnace has a curved shape such that the slag attached to the ceiling does not fall into the furnace, but falls along the side wall from the ceiling.

As shown in FIG. 4, the burner 3 is provided on the side wall 10 of the gasification furnace 1 at a certain angle with respect to the tangential direction of the furnace wall, and pulverized coal is blown together with the oxidizing agent. At the same time, the gas swirls in the furnace, prolonging the residence time of the coal particles in the furnace, suppressing the generation of unburned substances,
Generally, the molten ash in the coal collides with the gasification furnace side wall by the swirling force of the gas and is collected, so that the amount of slag discharged from the slag tap 4 is increased. The turning diameter of the burner indicates the angle indicated by the cut line of the burner in FIG. 4, and the burner is attached to the gasification furnace side wall at an angle. The solid line in FIG. 4 indicates the inner wall of the gasification furnace, and the dotted line indicates the burner turning diameter.

The cooling furnace 5 generally uses a boiler of a radiation type. However, as shown in Japanese Patent Application Laid-Open No. 5-295371, there is also a method of blowing coal to cool gas and pyrolyze the coal at the same time. .

[0006]

In a spouted bed gasifier, pulverized coal and an oxidizing agent are mixed and burned at a burner outlet provided in a side wall of the gasifier, and the burner is, as shown in FIG.
The gasified gas swirls inside the gasification furnace, and the char and the molten slag particles that have escaped from the gas and volatiles in the gasification furnace do not pass through the outlet at the top of the gasification furnace due to a short path. In general, molten slag strikes the gasification furnace side wall and is trapped.However, it is impossible to completely capture molten slag, and some of the molten slag is mixed with gas. It is accompanied and scatters from the gasifier outlet. The scattered slag adheres to and grows on a furnace wall of the cooling furnace or a cooling pipe provided in the cooling furnace in the cooling furnace, and thus the cooling furnace is clogged.

[0007] The cause of this is that when the coal is gasified, slag generated by melting of the ash in the coal adheres to the furnace wall of the throat at the outlet of the gasification furnace, and the attached slag further flows from the furnace wall of the throat. slag particles having a diameter of mm are scattered in the cooling furnace, adhere to the furnace wall of the cooling furnace, and solidify. By increasing the diameter of the throat and decreasing the gas flow velocity in the throat, the throat Is reduced on the furnace wall,
It is said that slag particles having a diameter of several mm can be prevented from scattering into the cooling furnace.

However, increasing the diameter of the throat portion increases the radiant heat from the gasification furnace to the cooling furnace and increases the heat loss from the gasification furnace, so that the cold gas efficiency of the gasification furnace (latent heat of gas / In addition to causing a decrease in the latent heat of coal), the heat load of the cooling furnace is undesirably increased. Also, Japanese Patent Application Laid-Open No. 5-29
As shown in Japanese Patent No. 5371, when the coal is blown into a pyrolysis furnace serving as a cooling furnace and the coal is to be pyrolyzed at the same time as the gas is cooled, the expansion of the throat diameter is as follows.
It is not preferable because the coal put into the pyrolysis furnace is likely to fall into the gasification furnace.

An object of the present invention is to prevent slag from scattering from the throat furnace wall without increasing the diameter of the throat, and to prevent blockage due to slag adhesion in the cooling section.

[0010]

Means of the present invention for solving the above problems are as follows.

(1) A gasifier having at least a ceiling, a side wall, and a bottom, and a burner provided around the inside of the gasifier, for blowing fine coal together with an oxidizing agent,
Coal gasification having at least a cooling furnace provided above the gasification furnace, and a throat located between the cooling furnace and the gasification furnace and communicating with a gas outlet at a ceiling of the gasification furnace and a gas inlet of the cooling furnace. In the apparatus, on the ceiling of the gasifier,
A coal gasifier comprising a projecting structure projecting downward.

(2) The coal gasifier according to (1), wherein the projecting structures are provided in a streak shape radially from the gas outlet of the gasification furnace ceiling toward the side wall. .

(3) The height of the protruding structure is 50 to 70
(1) or (2).

(4) The coal gasifier according to any one of (1) to (3), wherein the projection has a water-cooled structure.

In the present invention, by providing a projection on the ceiling of the gasification furnace, it becomes possible to attenuate the swirling force of the gas flow entering the throat, and the molten slag collected on the furnace wall of the throat can be reduced. This coal gasifier prevents molten slag from scattering into the cooling furnace because it can be moved to the gasification furnace ceiling wall without staying between the throat and the upper part of the gasification furnace.

The inventor of the present invention blows a high-viscosity liquid into a gasification furnace and observes the behavior of the gas and droplets in the throat in a cold state to investigate the behavior of the slag droplets in the gasification furnace and the throat. Analyzed. The droplets are supplied from the nozzle to the center of the gasifier, and the gas is swirled in the gasifier as shown in FIG. 4 at a rate corresponding to the gas quantity of the actual machine at a rate equal to the burner flow rate. From the nozzle. Most of the droplets collide with the side walls of the gasification furnace and are trapped, but some swirl inside the furnace and are accompanied by the gas to reach the throat.

In the throat, the gas collides with the throat furnace wall due to the swirling force of the gas, forms a liquid film, and falls along the throat section furnace wall. The dropped liquid moves to the furnace wall at the ceiling of the gasifier and is discharged from the slag tap along the gasifier side wall, but the swirling force of the burner is strong (the gasifier inner diameter shown in FIG. 4). When the ratio of the burner swirling diameter d to D is large, the droplets cover the furnace wall near the boundary between the throat and the ceiling of the gasification furnace to form a thick liquid film. It was found that this liquid was blown off from the furnace wall to the gas after growing large, and scattered as droplets of several mm. Although the surface of the droplet slag of several mm is cooled, only the surface is cooled, but the inside collides with the furnace wall while the temperature is high. Therefore, it was found from the particle cooling calculation that the melt inside adhered to the furnace wall. . On the other hand, the slag scattered directly from the gasification furnace to the cooling furnace is fly ash-like fine powder of several tens of microns, and when it reaches the furnace wall of the cooling furnace, it is cooled to the gas temperature, and when it reaches the cooling wall, However, there is no problem because it solidifies immediately on the cooling wall surface and does not adhere.

When the swirling force of the burner is weak or the throat diameter is large, the droplets collected on the furnace wall of the throat move to the ceiling of the gasification furnace. There was no accumulation, and droplets of several mm did not scatter. Therefore, reducing the burner turning force,
That is, scattering of the slag from the lower part of the throat can be prevented by reducing the turning diameter of the burner or increasing the diameter of the throat. However, if the swirling force of the burner is weak, the slag generated by the combustion of the pulverized coal collides with the side wall of the gasifier and is trapped. Then, fly ash scattered by the gas in the cooling furnace increases. This is one of the merits of the gas-bed gasifier, which reduces the rate of collecting ash in coal as granulated slag that is easy to handle and use, making fly ash difficult to collect and use. Is unfavorable from the viewpoint of increase.

Furthermore, reducing the swirl diameter of the burner means that the char particles from which volatile components in the coal have escaped do not swirl in the gasification furnace, and short-path pass out of the gasification furnace without gasification. Is increased, so that the gasification efficiency of coal is lowered. On the other hand, the expansion of the throat diameter is not only caused by an increase in radiant heat to the cooling furnace, but also by
As disclosed in Japanese Patent No. 371, a method of blowing coal into a pyrolysis furnace to cool a gas and pyrolyze the coal at the same time,
This is also undesirable from the viewpoint that the coal falls into the gasifier.

Therefore, the gasification efficiency and the recovery efficiency of the slag for water granulation can be improved without increasing the throat diameter by ensuring the swirling force of the burner and colliding with the furnace wall at the throat to collect the slag. As a result of studying how to prevent the molten slag from scattering and adhering to the cooling furnace as a large particle size slag, the gas swirling force in the gasification furnace was obtained by attaching a projection to the ceiling of the gasification furnace. Was attenuated before entering the throat, and it was confirmed that the molten slag did not cause liquid accumulation in the throat.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a coal gasifier according to the present invention, which comprises a gasifier 1, a throat 2, a gasifier burner 3, a slag tap 4, and a cooling furnace 5.
The projection 9 is provided on the ceiling 9 of the camera.

The gasifier 1 has a ceiling 9 and a cylindrical side wall 10.
And the bottom 11, and the gasification furnace 1 includes the gasification furnace 1
A pulverized coal gasification burner 3 disposed at an angle to the side wall of the gasification furnace 1 is attached so that gas gasified in the gas swirls therein. To gasify the coal. The gasified gas rises while turning inside the gasifier 1,
After passing through the throat 2 provided in the upper part of the gasification furnace, it enters the cooling furnace 5 above the throat 2. The ash in the coal becomes high-temperature molten slag in the gasification furnace 1, and most of the slag collides with the side wall 10 of the gasification furnace, accumulates in the gasification furnace bottom 11, and is discharged from the slag tap 4. It falls into the cooling water tank 6 at the lower part of the furnace and solidifies. The remaining ash enters the cooling furnace 5 from the throat 2 with the gas, but a part of the slag adheres to the furnace wall of the throat 2 and falls down along the throat side wall while being melted.

FIGS. 2A and 2B are cross-sectional views taken along the line AA of FIG. 1 showing the mounting state of the projections 7 provided on the ceiling 9 of the gasification furnace 1. FIG. The object 7 is radially attached to the curved gasification furnace ceiling 9 from the lower part of the throat 2 to the side wall. The shape and the number of the protrusions are as follows.
600mm, height 2200mm, throat 2 diameter 40
An apparatus equipped with four gasification burners 3 having a height of 0 mm and a height of 300 mm was used to perform a cold test while changing the burner swirling diameter, and the burner swirling diameter at which droplets were not scattered in the cooling furnace 2 was investigated. When there were no protrusions, the swirl diameter of the burner at which the droplets did not scatter was 400 mm or less.

The shapes of the protrusions were tested in two shapes shown in FIGS. a is one in which a plurality of continuous streak-like protrusions are radially arranged, and b is a single protrusion in which short protrusions are dispersed at substantially equal intervals and arranged in a streak form, and a plurality of radial protrusions are formed. It is located in. The number of projections was four, and the height of the projections was 50 mm. The results are shown in Table 1 as burner swirl diameters at which no droplets scatter.

[0026]

[Table 1] It can be seen that the burner turning diameter is larger when the protrusions are provided than when no protrusions are provided, and the burner turning diameter where the droplets are not scattered is greater when the continuous protrusions are provided. .

The number of protrusions indicates the number of streak-like protrusions attached to the side wall from the outlet of the gasification furnace ceiling.
a and b show four lines. The number of protrusions is 2 to 12
As shown in Table 3, the effect is increased as the number is increased from four to four, as shown in Table 3, but the degree of increase in the effect is reduced when the number exceeds eight. Therefore, four to eight are preferred.

[0028]

[Table 3] Table 4 shows the results obtained by changing the height of the protrusion. The effect increases as the height of the projection increases up to 70 mm. In other words, the turning diameter that does not cause scattering increases, but when the height exceeds 70 mm, the degree of the effect decreases. Therefore, the height of the projection is preferably 50 to 70 mm.

[0029]

[Table 4] Next, Table 2 shows the results of examining the effects of the projections with the cross-sectional shapes changed from those shown in FIGS.

[0030]

[Table 2] Regarding the cross-sectional shape of the projection, it seems that the effect is larger when the cross section is rectangular as shown in FIG. 3A, but the effect difference is smaller than that of the triangular shape shown in FIG. 3B. Therefore, the cross section may be determined in consideration of workability and the like.

The protrusion 7 on the ceiling of the gasification furnace is 1500 ° C.
Considering contact with a high-temperature gas of a certain degree, a material having heat resistance, for example, a heat-resistant material such as ceramics can be used. A boiler steel pipe may be used to form a projection having a water-cooled structure using cooling water or boiler feedwater inside. In this case, the molten slag is self-lined on the surface of the projection, and a deposit of 20 to 30 mm is attached. FIG. 3c shows a projection 7 on the ceiling of the gasification furnace with two pipes having an outer diameter of 34 mm.
In the example, the reference numeral 8 indicates the attached slag. Pipe 1
Although the protrusions may be formed by this arrangement, a plate-like protrusion having a height of 70 mm as shown in FIG. 3A could be formed.

[0032]

EXAMPLE Gasification was carried out using a gasifier as shown in FIG. The gasifier 1 has a diameter of 1600 mm,
At a height of 2200 mm, four gasification burners 3 are used,
Coal 1600 kg / h, the oxygen 1200 Nm ³ / h, and gasified at about 1500 ° C. using steam 800 Nm ³ / h. Throat 2 has a diameter of 400 mm and a height of 300 mm. The cooling furnace was cooled to 800 ° C. by the method of pyrolyzing and cooling coal described in JP-A-5-295371.
The cooling furnace is a method in which coal is blown into the lower part of the cooling furnace instead of a boiler, and the gasification gas is cooled by the coal and the coal is pyrolyzed at the same time. A burner swivel diameter shown in Table 1 and four protrusions each of which is formed by stacking two pipes each having a length of 500 mm and an outer diameter of 34 mm shown in FIG.
Table 5 shows the results obtained by attaching four pipes each having an outer diameter of 34 mm (projection height: 34 mm), and the results obtained when the pipes were not attached at four levels. The pipe used for the projection was cooled with saturated water at a temperature of 200 ° C., and the cooling heat was recovered with steam.

[0033]

[Table 5] When the projections were not provided on the ceiling of the gasification furnace, the slag collection rate was as high as 81% when the burner swirling diameter was 600 mm, but the cooling furnace was clogged in about 4 days and the operation was stopped. A mixture of slag and pyrolyzed char adheres to the cooling furnace.
Had solidified. Also, at a burner turning diameter of 400 mm,
The slag collection rate was as low as 65%, but there was no blockage even after 7 days of operation.

On the other hand, when two pipes were attached to the ceiling of the gasification furnace, the test was conducted for 7 days under the condition of a burner swirling diameter of 600 mm. However, no clogging occurred in the cooling furnace, and there was no deposit on the cooling furnace even after the operation was stopped. However, the slag collection rate was as high as 88%. Slag adhered to the protruding pipe as shown in FIG. 3c, but it protruded 70 mm or more from the furnace wall. The reason why the collection rate of the slag is higher than that in the case where there is no protrusion is that the slag is also collected by the protrusion. With one pipe, there was no deposit on the cooling furnace at the burner turning diameter of 500 mm in the test for 7 days, but there was no deposit at the burner turning diameter of 600 mm, but there was deposit on the cooling furnace.

As a result, it can be seen that it is preferable to use a projection to which two pipes are attached for long-term use.

In this embodiment, the gasification of coal with oxygen has been described. However, the present invention can also be applied to gasification of a substance containing ash such as char, and also to an oxidizing agent using air. Further, the present invention can be applied not only to gasification of coals but also to a refuse melting furnace in which refuse is burned in a spouted bed to perform melting treatment. As the projection, a cooled pipe was used, but a heat-resistant material such as ceramics can also be used. Although the embodiment in which the cooling furnace is cooled with coal has been described, it is natural that the cooling furnace is also effective in a method using a radiation boiler.

[0037]

According to the present invention, a high slag collection rate is ensured, large-sized molten slag is prevented from being scattered from the throat portion, and the cooling furnace is prevented from being clogged to remove coal gas. Will be possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a coal gasifier of the present invention.

FIG. 2 is a plan view (AA in FIG. 1) showing an embodiment of the arrangement of projections on the ceiling of the gasifier of the coal gasifier of the present invention.
(A) is an example in which (a) is provided integrally and continuously;
(B) is a figure which shows the example provided in distributed.

FIG. 3 is a cross-sectional view showing a shape of a projection on a ceiling of a gasification furnace of a coal gasifier of the present invention, where (a) is a rectangular cross section, (b) is a triangular cross section, and (c). FIG. 3 is a view showing a state in which pipes are arranged with pipes overlapped.

FIG. 4 is a conceptual diagram illustrating a turning diameter of a gasification burner in a coal gasifier.

FIG. 5 is a diagram showing a schematic configuration of a conventional coal gasifier.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gasification furnace 2 Throat 3 Gasification burner 4 Slag tap 5 Cooling furnace 6 Cooling water tank 7 Projection of gasification furnace ceiling part 8 Slag 9 Gasification furnace ceiling part 10 Gasification furnace side wall part 11 Gasification furnace bottom part

Claims (4)

[Claims] 1. A gasification furnace having at least a ceiling, a side wall, and a bottom, a burner provided around the inside of the gasification furnace, for blowing fine coal together with an oxidizing agent, and an upper part of the gasification furnace. A coal gasifier having at least a cooling furnace provided in the furnace and a throat located between the cooling furnace and the gasification furnace and communicating with a gas outlet of a ceiling portion of the gasification furnace and a gas inlet of the cooling furnace. A coal gasifier, comprising a projecting structure projecting downward on a ceiling of a furnace. 2. The coal gasifier according to claim 1, wherein the projecting structures are provided in a streak shape radially from the gas outlet of the gasification furnace ceiling toward the side wall. 3. The height of the protruding structure is 50 to 70 mm.
The coal gasifier according to claim 1 or 2, wherein: 4. The coal gasifier according to claim 1, wherein the projection has a water-cooled structure.