KR101674983B1 - Multi-stage fluidized bed coal dryer and coal drying method using it - Google Patents

Abstract

The present invention relates to a multi-stage fluidized-bed coal drying apparatus capable of utilizing surplus gas or waste gas for coal fluidization and drying, and a coal drying method using the same.
The multistage fluidized-bed coal drying apparatus supplies coal to the internal space of the main body through the coal supplying section and is dried by the hot gas supplied through the gas supplying section while the supplied coal flows through the internal space of the main body section by the returning section, The hot gas from which the coal is dried is discharged to the gas discharge portion, and the dried coal is discharged through the coal discharge portion.
From this, it is possible to increase the total residence time of coal in the multi-stage fluidized-bed coal drying apparatus, reduce the installation area of the multistage fluidized-bed coal drying apparatus, maximize the sensible heat of the hot gas, .

Description

TECHNICAL FIELD [0001] The present invention relates to a multi-stage fluidized-bed coal drying apparatus and a coal drying method using the same,

The present invention relates to a coal drying apparatus and a coal drying method using the same, and more particularly, to a multi-stage fluidized-bed coal drying apparatus capable of utilizing a surplus gas or waste gas at a high temperature for coal fluidization and drying, and a coal drying method using the same.

Worldwide coal fuels are used extensively for thermal power generation. Generally, coal is divided into anthracite, bituminous coal, bituminous coal and lignite depending on the moisture and calorific value contained in the coal. Among these, bituminous coal and lignite are called low-grade coal because the water contained in coal is high and the calorific value is low. In recent years, efforts have been made to increase the availability of low-priced coal, which is low in price due to the rise in coal prices, and to improve the economy. Therefore, there is a growing interest in drying coal to improve the utilization of low grade coal.

A variety of heat exchangers may be used to dry the coal. A coal drying method such as a rotary kiln, a long slot dryer, a hopper dryer, a moving bed dryer, and a fluidized bed dryer was applied. Among these, a fluidized bed drying apparatus using a bubble fluidized bed capable of utilizing surplus gas or waste gas at a high temperature for coal fluidization and drying is widely used.

As shown in FIG. 1, the conventional fluidized-bed drying apparatus is constructed such that the coal supplied to the fluidized-bed drying apparatus through the coal supply unit forms a coal fluidized bed by the hot gas injected from the lower part of the fluidized bed drying apparatus, ≪ / RTI >

However, the conventional fluidized bed drying apparatus has a problem that the installation area of the fluidized bed drying apparatus must be enlarged in order to sufficiently secure the flow residence time of the coal. To solve these problems, attempts have been made to install several diaphragms in the fluidized bed, but there has been a limit to the area reduction of the drying apparatus.

In addition, since the conventional fluidized bed dryer discharges high-temperature gas through the bottom of the fluidized-bed dryer and then discharges the coal quickly, the sensible heat of the high-temperature gas can not sufficiently be used for drying the coal. In order to solve these problems, a heat exchanger in which a high temperature steam or water flows in the inside of the fluidized bed dryer has been installed, but the problem that the sensible heat of the hot gas can not be fully utilized remains.

Korean Patent Laid-Open Publication No. 10-2011-0098445 (entitled Coal Drying Apparatus and Coal High-Quality System Containing the Coal Drying Apparatus) Korean Patent Registration No. 10-1114522 (entitled Powder Drying Apparatus)

In order to solve the problems of the background art described above, the present invention provides a multi-stage fluidized-bed coal drying apparatus having a plurality of retention plates spaced up and down so that coal can be recirculated and dried in the coal drying apparatus, and a coal drying method using the same The purpose is to provide.

According to an aspect of the present invention, there is provided a multi-stage fluidized-bed coal drying apparatus comprising: a main body having an internal space; A coal supply unit for supplying coal to the upper portion of the main body; A coal discharge unit for discharging coal to a lower portion of the main body; A plurality of retention plates arranged horizontally and vertically spaced apart from each other in the inner space so as to allow the coal supplied from the coal supply unit to flow through the inner space and to be discharged through the coal discharging unit and a plurality of retention plates horizontally disposed between the inner wall of the main unit and the plurality of retention plates A reflux portion having a flow space through which coal can flow downward; A gas supply unit having a plurality of jet openings for supplying hot gas to the upper portion of the retention plate to supply hot gas to the inner space to dry coal; And a gas discharge unit for discharging gas supplied through the gas supply unit. Wherein the width of the flow space increases toward the upper portion of the main body portion and the transverse sectional area of the main body portion increases with an increase toward the upper portion so that the inclined surface is formed so as not to be filled with coal at the position where the inner wall of the main body portion and the stay plate are engaged. Respectively,
The high temperature gas flows into the interior of the stay plate from the outside of the main body and is supplied to the internal space through the injection port. The injection port is densely arranged on the inner wall side of the main body in comparison with the other side, The size of the jetting port disposed on the inner wall side is relatively large.

Preferably, the plurality of retention plates are alternately provided on opposite inner walls of the inner space.

Preferably, the ratio of the width of the retention plate to the width of the flow space in the direction of extension of the retention plate is 7: 3 to 10: 1.

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Preferably, the cross-sectional area of the body portion increases with an increase toward the upper portion. At least a pair of facing inner walls of the main body have an inclination angle of 10 ° to 30 ° with respect to a vertical central axis of the main body.

Preferably, an inclined surface is provided at a position where the inner wall of the main body and the stay plate are coupled with each other so that the coal is not accumulated. At this time, the inclined surface has an inclination angle of 30 ° to 45 ° with respect to the horizontal plane of the retention plate.

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Preferably, the retention plate further comprises at least one heat exchange portion at the top. At this time, the heat exchanger is formed as a manifold heat exchanger.

According to another aspect of the present invention, there is provided a coal drying method comprising: a coal supplying step of supplying coal to the coal supplying unit using the multistage fluidized bed coal drying apparatus; A coal drying step of drying the coal supplied by the hot gas supplied through the gas supply part while the coal is circulated in the inner space, and discharging the hot gas dried by the coal to the gas discharge part; And a coal discharging step of discharging coal dried to the coal discharging unit; .

According to the multistage fluidized-bed coal drying apparatus of the present invention, as the coal is refluxed by the plurality of retention plates in the multistage fluidized-bed coal drying apparatus, the total residence time of coal in the multistage fluidized-bed coal drying apparatus is increased to increase the drying efficiency of coal .

Further, since the plurality of retention plates are vertically spaced, the installation area of the multi-stage fluidized-bed coal drying apparatus can be reduced.

Also, as the hot gas injected from the injection port located at the lower part of the multi-stage fluidized-bed coal drying apparatus rises, the coal is continuously dried, thereby maximizing the sensible heat of the hot gas, thereby improving the operation efficiency of the multistage fluidized-bed coal drying apparatus.

1 is a perspective view of a conventional fluidized bed drying apparatus.
2 is a sectional view of a multi-stage fluidized bed coal drying apparatus according to a first embodiment of the present invention.
3 is a cross-sectional view of a multi-stage fluidized-bed coal drying apparatus illustrating the flow of coal in the present invention.
4 is a cross-sectional view of a multi-stage fluidized-bed coal drying apparatus showing the flow of hot gas in the present invention.
5 is a flow chart illustrating a multi-stage fluidized-bed coal drying method according to a first embodiment of the present invention.
6 is a sectional view of a multi-stage fluidized bed coal drying apparatus according to a second embodiment of the present invention.
7 is a sectional view of a multi-stage fluidized-bed coal drying apparatus according to the third and fourth embodiments of the present invention.
8 is a sectional view of a multi-stage fluidized bed coal drying apparatus according to a fifth embodiment of the present invention.
FIG. 9 is a cross-sectional view taken along the line AA of FIG. 2 showing an arrangement of an injection hole according to a sixth embodiment of the present invention;
FIG. 10 is a sectional view taken along line AA of FIG. 2 showing another nozzle array according to a seventh embodiment of the present invention;
11 is a sectional view of a multi-stage fluidized-bed coal drying apparatus according to eighth and ninth embodiments of the present invention.
12 is a perspective view of a manifold heat exchanger constituting the present invention.

Best Mode for Carrying Out the Invention Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The various embodiments of the present invention are also applicable to the first to fourth embodiments in accordance with the difference in shape and structure of the flow space, the inner wall of the main body 10, the retention plates 41 to 44, the injection ports 51 to 54, And the ninth embodiment. The second to ninth embodiments are basically the same as those of the first embodiment, but in the second embodiment, the flow space, the inner wall of the main body 10 in the third embodiment, and the retention plates 41 to 44), the jetting ports 51 to 54 in the sixth and seventh embodiments and the heat exchanging part 70 in the eighth and ninth embodiments are different from the first embodiment. In addition, among the various embodiments of the present invention, the same reference numerals in the drawings are used for the same functional elements and functions.

1. First Embodiment

2, the multistage fluidized-bed coal drying apparatus according to the first embodiment of the present invention includes a main body 10, a coal supply portion 20, a coal discharge portion 30, a reflux portion 40, (50) and a gas discharge portion (60).

The main body 10 has an inner space through which coal can be dried. Although not shown in the drawings, the cross-sectional shape of the main body 10 may be a polygonal shape such as a square, a rectangle, or the like.

The coal supply part 20 is located at the upper part of the main body part 10 to supply coal containing moisture to the internal space of the main body part 10.

The coal discharging portion 30 is positioned below the main body 10 and discharges the dried coal in the internal space of the main body 10.

The circulation unit 40 is provided in the inner space so that the coal supplied from the coal supply unit 20 is circulated through the inner space to be dried and discharged through the coal discharge unit 30. The inner space of the main unit 10, And a plurality of staying plates (41 to 44) so that a flow space through which coal can flow downward is formed between the bottom plates (40). The plurality of retention plates 41 to 44 are vertically spaced apart from each other and alternately arranged on the inner wall of the main body 10 so as to repel the coal, thereby increasing the time for the coal to stay in the inner space.

At this time, the ratio of the width d ₁ of the retention plate to the flow space width L ₁ in the extending direction of the retention plates 41 to 44 can be set to 7: 3 to 10: 1. When the width d ₁ of the retention plate becomes too narrow, the coal on the first retention plate 41 located at the uppermost portion of the main body 10 is close to the free end of the upper portion of the second retention plate 42, The first stay plate 41 and the second stay plate 42 can be prevented from falling down to the lower portion of the main body 10 through the wide flow space. On the contrary, when the width d ₁ of the retention plate becomes too wide, the flow space L ₁ becomes relatively narrow, and the flow of the coal above the first retention plate 41 to the upper portion of the second retention plate 42 May be lacking. On the other hand, although not shown in the drawing, the width d ₁ of each retention plate may be designed differently.

The gas supply part 50 is composed of jetting ports 51 to 54 located above the retention plates 41 to 44 and is configured to fluidize and heat the coal staying on the retention plates 41 to 44 to the main body part 10) to the inner space. The hot gas is introduced into the stay plates 41 to 44 from the outside of the main body 10 and then injected onto the stay plates 41 to 44 through the injection ports 51 to 54. At this time, the shape, the number, the position, and the jetting direction of the jetting ports 51 to 54 can be adjusted so that the coal can flow horizontally toward the flow space forming the fluidized bed at the upper portion of the retention plates 41 to 44.

The width d ₁ of each retention plate, the width L _{1 of} each flow space and the vertical distance h of the retention plates 41 to 44 are determined by the particle size of the coal, The flow rate of the hot gas supplied from each of the injection ports 51 to 54, and the flow rate of the hot gas passing through the flow space.

The gas discharging portion 60 is located above the main body portion 10 and discharges the high temperature gas supplied from the gas supplying portion 50 and dried to the outside of the main body portion 10. In this case, the high-temperature gas discharged contains steam and fine dust contained in the coal. A dust collector may be installed in the gas discharge portion 60 to remove fine dust in the discharged gas. In addition, a component for raising the gas temperature at the front of the dust collector may be installed, or the pipe may be insulated while the gas is going to the dust collector, The water vapor can be prevented from condensing.

Hereinafter, the process of drying the coal by the multistage fluidized-bed coal drying apparatus of the present invention will be described with reference to FIG. 2 to FIG.

First, in the coal supplying step (S10), coal including moisture is supplied into the main body 10 through the coal supplying part 20. [

In the coal drying step S20, hot coal supplied from the injection ports 51 to 54 while the supplied coal stays above the first retention plate 41 located at the uppermost position of the main body 10, 44) to fluidize and dry the coal so that it can move horizontally toward the flow space. The coal which is dried on the first retention plate 41 and reaches the free end of the first retention plate 41 falls down onto the second retention plate 42 through the flow space and stays on the second retention plate 42 Lt; / RTI > In this way, coal as many as the number of the staying plates 41 to 44 is collected and separated from the bottommost stay plate 44 is collected at the lower portion of the main body 10 and is simultaneously discharged through the jetting ports 51 to 54 The supplied hot gas is collected at the upper portion through the flow space after the coal is dried and discharged to the gas discharge portion 60.

Finally, in the coal discharging step S30, the dried coal collected at the lower portion of the main body is discharged through the coal discharging portion 30. [

The following second to ninth embodiments are the same as the coal drying apparatus of the first embodiment except for the differences in the shape and the structure of some of the constituent elements, and therefore the description of the same parts is omitted.

2. Second Embodiment

6, the flow space widths L ₁ to L _{4 at the} respective ends can be made wider toward the upper portion of the main body portion 10 as the second embodiment. This can solve the problem that the high temperature gas injected from the injection ports 51 to 54 rises through the flow space of each stage and the gas flow rate on the upper portion of the main body portion 10 is relatively increased.

3. Third Embodiment

In the third embodiment, as shown in Fig. 7, the transverse sectional area of the main body 10 can be made wider as it goes higher. This can solve the problem that the high temperature gas injected from the injection ports 51 to 54 rises through the flow space of each stage and the gas flow rate on the upper portion of the main body portion 10 is relatively increased.

At this time, the inner wall of the main body 10 can have an inclination angle? ₁ of 10 to 30 degrees with respect to the vertical central axis of the main body 10, and an excessively small inclination angle can be obtained when the cross- The effect of widening toward the upper portion can not be expected, and a too large inclination angle increases the installation area more than necessary compared with the effect.

4. Fourth Embodiment

7, an inclined surface 41a is provided at a position where the inner wall of the main body 10 is coupled with the retention plates 41 to 44, Can be prevented.

At this time, the inclined surface 41a may have an inclination angle θ ₂ of 30 ° to 45 ° with respect to the horizontal plane of the retention plates 41 to 44, and the angles of the inclined surfaces may be the same or different. Too large or small inclination angles may have little effect of preventing the coal from being accumulated on the retaining plates 41 to 44.

5. Fifth Embodiment

8, the retention plates 41 to 44 are inclined downward with respect to the inner wall of the main body 10 so that the coal is effectively horizontally moved from above the retention plates 41 to 44 toward the flow space, .

At this time, the retention plates 41 to 44 may have an inclination angle? ₃ of 3 to 10 degrees with respect to the vertical plane of the inner wall of the body 10, and the inclination angles of the retention plates may be the same or different. Too small an inclination angle has a small effect of horizontally moving coal toward the flow space from above the staying plates 41 to 44 and a too large inclination angle causes the coal to move too fast at the top of the staying plates 41 to 44, You can not have it.

6. Sixth Embodiment

9, the injection ports 51 to 54 for injecting the high-temperature gas at the top of the retention plates 41 to 44 are provided with fixed-end-side injection ports 51 to 54 of the retention plates 41 to 44, ~ 54) arrangement can be arranged more tightly than the other arrangement. This can help the horizontal movement of the coal toward the flow space above the retaining plates 41-44.

7. Seventh Embodiment

As a seventh embodiment, as shown in Fig. 10, the jetting ports 51 to 54 for jetting the high-temperature gas at the upper portions of the retention plates 41 to 44 are arranged on the fixed end side of the retention plates 41 to 44 The size of the jetting ports 51 to 54 can be relatively increased. This can help the horizontal movement of the coal toward the flow space above the retaining plates 41-44.

8. Eighth Embodiment

If it is difficult to sufficiently dry the coal because the temperature of the high temperature gas injected from the injection ports 51 to 54 is not high enough, the multistage fluidized bed coal drying apparatus may further include a heat exchange unit 70 to add components for drying the coal have. In the eighth and ninth embodiments, the multi-pipe heat exchangers (71 to 73) are applied as the heat exchanging unit (70). However, the shape of the heat exchanging part 70 is not limited to the multi-channel heat exchangers 71 to 73, but may be any device capable of heat exchange.

As shown in Fig. 11, in the eighth embodiment, manifold heat exchangers 71 and 72 are added to the upper portions of the retaining plates 41 to 44 so that the heat of the coal is exchanged through the heat exchange between the coal and the manifold heat exchangers 71 and 72 The temperature can be raised to help dry the coal. At this time, one or more of the manifold heat exchangers 71 and 72 may be added, and the manifold heat exchangers 71 and 72 may be installed on at least one of the staying plates 41 to 44.

9. Ninth Embodiment

11, a multicomponent heat exchanger 73 is added to the front end of the coal discharge port 30 where coal dried by the high temperature gas is collected, so that the coal is further dried or dried at a high temperature The temperature of the coal can be lowered before it is discharged to the coal discharging portion 30.

The manifold heat exchangers 71 to 73 are composed of a suction pipe 71a, a distribution pipe 71b, a branch pipe 71c, a composite pipe 71d and a discharge pipe 71e as shown in Fig. The suction pipe 71a sucks high-temperature steam or water into the manifold heat exchangers 71-73. The distribution pipe 71b flows high-temperature steam or water sucked in through the suction pipe 71a into branch pipes 71c divided into several branches. The branch pipe (71c) is made up of a plurality of pipes. The branch pipe (71c) exchanges heat with coal using high temperature steam or water introduced through the distribution pipe (71b) to help dry the coal. The joint pipe (71d) combines the high-temperature steam or water that has undergone the heat exchange in the branched branch pipe (71c). The discharge pipe 71e discharges steam or water of high temperature combined with the pipe 71d to the outside of the manifold heat exchangers 71-73.

While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10:
20: Coal Supply Department
30: coal discharge section
40:
41, 42, 43, 44: first, second, third, and fourth retention plates
50: gas supply part
60:
70: Heat exchanger
71, 72, 73: manifold heat exchanger

Claims (18)

A body portion (10) having an internal space;
A coal supply unit 20 for supplying coal to the upper portion of the main body 10;
A coal discharge unit 30 for discharging coal to the lower portion of the main body 10;
A plurality of circulation units 40 provided in the inner space so that coal supplied from the coal supply unit 20 flows through the inner space and is discharged through the coal discharge unit 30;
A plurality of gas supply units 50 for supplying a hot gas to the inner space to dry the coal; And
And a gas discharge portion (60) for discharging the gas supplied through the gas supply portion (50)
A plurality of horizontally arranged upper and lower spacers (not shown) are disposed in the inner space so as to form a flow space between the inner wall of the main body 10 and the return unit 40, Retention plates 41 to 44 are provided,
The plurality of the retention plates 41 to 44 are alternately provided on the inner wall of the inner space facing each other and the width d ₁ of the retention plate and the flow space A width (L ₁ ) of 7: 3 to 10: 1,
The flow space width L ₁ increases toward the upper portion of the main body portion 10,
The cross-sectional area of the body portion 10 increases as it goes to the upper portion,
At least a pair of facing inner walls of the main body 10 have an inclination angle? ₁ of 10 to 30 degrees with respect to a vertical central axis of the main body 10,
The inclination angle? ₂ (? ₂ ) of 30 ° to 45 ° with respect to the horizontal plane of the retention plates 41 to 44 is set so that coal does not accumulate at a position where the inner wall of the main body 10 and the retention plates 41 to 44 are engaged, (41a) having an inclined surface (41a)
The gas supply unit 50 has a plurality of injection ports 51 to 54 for supplying a high temperature gas to the upper portions of the retention plates 41 to 44,
The hot gas flows into the interior of the stay plates 41 to 44 from the outside of the main body 10 and is supplied to the internal space through the injection ports 51 to 54,
The jetting ports 51 to 54 are densely arranged on the inner wall side of the main body portion 10 in comparison with the other side or the sizes of the jetting ports 51 to 54 disposed on the inner wall side of the main body portion 10 are relatively As shown in FIG.
Wherein the retention plates (41 to 44) further comprise at least one heat exchanging part (70) formed on the upper part by multi-channel heat exchangers (71 to 73). delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete In the coal drying method using the multistage fluidized-bed coal drying apparatus of claim 1,
A coal supplying step of supplying coal to the coal supplying unit 20;
A coal drying step of drying the supplied coal by the hot gas supplied through the gas supply part 50 while the inner space is circulating and discharging the hot gas dried by the coal to the gas discharge part 60; And
A coal discharging step of discharging the dried coal to the coal discharging unit 30;
And drying the coal.

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