JPH06174201A - Fluidized-bed combustion furnace - Google Patents

Abstract

PURPOSE:To enable keeping the temperature of the fluidized bed constant even when the amount of heat evolved from the burned material varies frequently and enable reducing the abrasion of heat-transfer pipes by fluidization medium. CONSTITUTION:From the fluidization medium 31 flowing into a heat-recovery part 36 from the fluidized bed of a combustion part 34 in which a material for combustion is burnt heat is absorbed through a group of boiler water tubes 35 and utilized. The fluidization medium 31 at the outlet 45 of a hopper 38 of the heat-recovery part 36 is forced to flow back into the fluidized bed of the combustion part 34 by ejection of air from the mouth 43 as supplied under control by a valve 26; the flow of the fluidization medium 31 in the hopper 38 to the outlet 45 is turned on and off and the rate of the flow is also controlled; the amount of heat absorbed in the heat exchange, in which the absorption of heat from the fluidization medium 31 is stopped and started alternately, is controllable with improved accuracy so that, with the temperature of the fluidized bed made constant, the furnace can be better controlled than ever. By keeping the heat-recovery part 36 from flow of fluidizing air the abrasion of the group of boiler water tubes 35 by the fluidization medium 31 can be minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed combustion furnace which controls the bed temperature while recovering the combustion energy of incineration materials and the like.

[0002]

2. Description of the Related Art FIG. 6 is a longitudinal sectional view showing the structure of a conventional fluidized bed combustion furnace. In FIG. 6, a fluidized bed 5 for fluidizing a fluidized medium by fluidized air 4 which is guided to an air chamber 2 at an inner bottom portion of a furnace 1 and blows upward through an inclined blowing surface 3.
Is divided by a partition wall 6 into a heat recovery section 7 and a combustion section 8 for supplying combustion products. In the fluidized bed 5 of the combustion unit 8, the amount of the fluidized air intake air per unit area in the vicinity of the partition wall 6 of the combustion unit 8 is set to be larger than the amount of the fluidized air intake air per unit area of the heat recovery unit 7. As shown by arrow A, the fluidized medium in the upper layer portion passes through the partition wall 6 and passes through the gap between the water pipes 10 and flows into the heat recovery portion 7. The heat of the flowing medium that has flowed in is recovered by heat exchange with the group of heat transfer tubes 11. Then, in the heat recovery part 7, the pressure of the lower part is increased by the flowing-in fluid medium, and the lower part of the fluid medium flows from the gap of the water pipes 10 group of the reflux communication part 9 in the lower part of the partition wall 6 to the combustion part as shown by an arrow B. Reflux to 8.

[0003]

However, in the above-mentioned conventional configuration, the flow of the fluidized medium between the heat recovery section 7 and the combustion section 8 is caused by the difference in the fluidized air intake air volume between the combustion section 8 and the heat recovery section 7. Therefore, the bed temperature is kept constant when the reflux amount of the fluidized medium cannot be accurately controlled and the calorific value of the combustion product fluctuates well because the fluidized medium is recirculated only by the pressure of the fluidized medium flowing into the heat recovery section 7. It was difficult to control. Further, since the fluidized air 4 was also made to flow through the heat recovery section 7 that recovers heat by utilizing the combustion energy of incineration materials, there was a risk of wear due to the fluidized medium hitting the heat transfer tubes 11 for heat exchange. .

The present invention solves the above-mentioned problems of the prior art by controlling the bed temperature at a constant level and reducing the wear of the heat transfer tube due to the fluidized medium even when the heat value of the combustion product fluctuates well. The object is to provide a fluidized bed combustion furnace capable of

[0005]

In order to solve the above-mentioned problems, a fluidized bed combustion furnace of the present invention supplies a fluidizing gas to a fluidized medium to fluidize the fluidized medium, and at the same time, a combustion product is supplied to burn the fluidized material. And a heat recovery section for controlling the bed temperature by absorbing heat from the fluidized medium flowing from the combustion section through the heat transfer tube group, the stage having a large upper volume. A portion is provided on the inner peripheral portion of the heat-resistant outer wall, and a partition member is provided above the step portion to divide the heat-resistant outer wall inner peripheral portion so as to have the heat recovery portion, and the bottom portion of the heat recovery portion and the An outlet part for communicating a combustion part is provided between the step part and the partition member, and a fluidizing gas jet part for forcibly refluxing the fluidized medium of the outlet part to the combustion part side is provided in the heat-resistant outer wall inner peripheral part, Of the fluidizing gas to the pipe part connected to the fluidizing gas jetting part. It is provided with a controllable fluidization gas quantity control member supply volume.

[0006]

With the above structure, the fluidized medium at the outlet of the heat recovery unit that absorbs heat from the fluidized medium flowing from the combustion unit is changed according to the supply amount of the fluidized gas controlled by the fluidized gas amount control unit. Since the fluidized gas is forcibly recirculated to the combustion section by the fluidized gas jet section, the heat from the fluid medium is absorbed while controlling the on / off flow of the fluid medium in the heat recovery section to the outlet and also controlling the degree of the flow. The amount of heat absorbed by heat exchange with or without heat treatment can be controlled more accurately, and the furnace can be controlled better with a constant bed temperature. Further, if the fluidizing gas is prevented from flowing to the heat recovery section side as much as possible, the wear of the heat transfer tube group due to the fluidized medium can be suppressed to the minimum.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing a partial configuration of a fluidized bed combustion furnace according to an embodiment of the present invention. In FIG.
At the lower part of the inner surface of the caster outer wall 21 that constitutes the heat-resistant outer wall of the furnace body, there is provided a stepped portion 23 formed by a horizontal plane that extends to the outside, connected to an inclined portion 22 that is slightly inclined from the vertical direction, and the upper volume of the furnace is It is getting bigger. In this step portion 23, one end of a pipe 24 provided penetrating the inside of the caster outer wall 21 is opened vertically upward. The other end of the pipe 24 is connected via an air reservoir 25 to a valve 26 as a fluidizing gas amount control unit capable of controlling the supply air amount.
26 is connected to an air supply device 27 such as a blower. In addition, a slightly inclined inclined portion 29 is provided continuously between the inclined portion 28 provided continuously to the inner side of the step portion 23 and the upper inner surface of the caster outer wall 21 which is vertical.

Further, a dispersion plate 30 is horizontally arranged below the inclined portion 22, and a fluid medium 31 is accommodated on the dispersion plate 30 up to a position of the stationary layer height D. Also, dispersion plate
An air chamber 32 is provided in the lower part of 30, and in the inner bottom portion of the furnace, the fluidized air 33 as the fluidized gas guided to the air chamber 32 is blown upward through the blowing surface of the dispersion plate 30. is there. This fluidized air 33 causes the fluidized medium 31 to move to a fluidized bed height E.
And a combustion section 34 in which a combustion product is supplied and burned while fluidizing to a position of
A partition wall 37 as a partition member for partitioning the heat recovery part 36 that absorbs heat from the fluid medium 31 flowing in from the fluidized bed of ing.

Further, the top portion of the partition wall 37 is formed by a horizontal plane, and one side surface of the partition wall 37 is formed by an inclined portion 39 which faces the inclined portion 29 of the caster outer wall 21 and forms a hopper portion 38. . Also, the other side surface of the partition wall 37 is the caster outer wall 21.
It is composed of an inclined portion 40 that is inclined so as to match the surface of the inclined portion 22 at the bottom of the. Further, the bottom surface of the partition wall 37 is composed of two surfaces, and the inclination angle θ of the rear inclined surface 41 on the hopper portion 38 side is such that the fluid medium 31 of the fluidized bed is transferred from the combustion portion 34 to the heat recovery portion 36. The inclination angle is set to coincide with the angle of repose that sometimes accumulates. In addition, an inclined surface 42 on the fluidized bed side of the bottom surface of the partition wall 37
Faces an opening 43 as a fluidized gas jetting portion of the pipe 24, and is inclined upward so that when air is jetted from the opening 43, the air flows toward the fluidized bed. Furthermore, the partition wall
A boiler water pipe 44 similar to the boiler water pipe 35 inside the hopper portion 38 is arranged in the heat insulating member of 37 in consideration of the life. Further, an outlet portion 45 to the fluidized bed of the hopper portion 38 is provided between the step portion 23 and the partition wall 37, and the bottom portion of the hopper portion 38 and the combustion portion 34 are communicated with each other.

At this time, the boiler heat transfer surface composed of the 35 groups of boiler water pipes is several tens of meters below the upper medium repose angle (about 35 °).
m or less. Further, the group of boiler water pipes 35 is provided in a range where the cross-sectional areas of the fluidized bed and the freeboard change. That is, the boiler water pipe group 35 is provided in a range between the stationary bed height D and the fluidized bed height E of the fluidized medium 31. Further, the outlet portion 45 of the hopper portion 38 is located below the surface of the stationary layer height D, and has a shape such that the inside of the outlet and the outlet tip have an angle of repose or a little smaller angle so that the internal medium does not spontaneously flow out. To do. Furthermore, since the upper surface of the hopper section 38 must be lower than the fluidized bed height E in order to transfer the fluidized medium 31 from the combustion section 34 to the heat recovery section 36, it is about 1/3 of the stationary bed height D and is stationary. The position is higher than the upper surface of the layer height D.

The operation of the above arrangement will be described below. First, the fluidized air introduced into the air chamber 32 at the bottom of the furnace
33 is fluidized from the stationary bed height D to the fluidized bed height E by blowing upward through the blowing surface of the dispersion plate 30. Next, in the combusting section 34, the combusted material is put into the fluidized bed and combusted. In particular, when the combustion product is a sludge-like substance, the part that is difficult to burn burns to the end while drying in the fluidized bed. Then, the fluidized bed height E is fluidized to be higher than the upper surface of the hopper portion 38, and the fluidized medium whose temperature has risen
31 is transferred from the combustion section 34 to the heat recovery section 36. In this way, the heat of the fluidized medium 31 that has flowed into the heat recovery unit 36 is recovered by heat exchange with the boiler water pipe group 35. Then, in the hopper portion 38 of the heat recovery portion 36, the pressure of the lower portion is increased by the inflowing fluid medium 31, and the lower portion of the fluid medium 31 tries to recirculate from the outlet portion 45 at the lower portion of the hopper portion 38 to the combustion portion 34 side. However, since the bottom of the hopper 38 and the outlet end are shaped so as to form an angle of repose or an angle slightly smaller than that, the fluid medium 31 therein has the outlet 45 at the bottom of the hopper 38.
Does not spontaneously flow out to the combustion section 34 side.

Here, air is jetted from the opening 43 of the pipe 24, and the jetted air flows to the fluidized bed side together with the fluidized medium 31 by the slanted surface 42 of the partition wall 37 which is slanted upward. By the movement of the fluidized medium 31 to the outlet portion 45 in the lower portion of the 38, the fluidized medium 31 inside the hopper portion 38 also passes through the group of boiler water pipes 35 and flows down to the lower portion of the hopper portion 38 while exchanging heat. As a result, the upper surface position of the hopper portion 38 is lowered. Due to the lowering of the upper surface position of the hopper portion 38, the fluidized bed height E relatively rises, and the fluidized medium 31 whose temperature has risen due to combustion again transfers from the combustion portion 34 to the heat recovery portion 36. The heat of the inflowing fluid medium 31 is recovered again by heat exchange with the boiler water pipe group 35, and this is repeated.

At this time, the amount of air flowing from the opening 43 to the fluidized bed side through the outlet 45 is controlled by the valve 26 to control the hopper 38.
While turning on / off the flow of the internal fluid medium 31 and controlling the degree of the flow, the amount of heat exchanged by the boiler water pipes 35 group may be improved by absorbing or not absorbing the heat from the fluid medium 31. Since the fluidized medium 31 is forcibly refluxed between the combustion section 34 and the heat recovery section 36 with accurate control, the furnace can be better controlled with the bed temperature kept constant. Further, the ceiling surface facing the opening 43, which is the outlet of the jetted air, is inclined upward toward the inside of the fluidized bed, and since fluidized air does not flow to the hopper portion 38 side, wear of the boiler water pipes 35 group by the fluidized medium 31 occurs. Can be minimized.

In the present embodiment, the inclined surface 42 of the partition wall 37 facing the opening 43 of the pipe 24 is blown to the fluidized bed through the outlet 45 when the air is jetted from the opening 43. In addition, the fluid medium 31 is inclined upward so that the fluid medium 31 flows, but as shown in FIG. 2, the pipe 52 is provided below the inclined portion 28 of the caster outer wall 21 so that the opening 52 of the pipe 51 faces the fluidized bed 53 side. A structure may be provided in which air is jetted toward the fluidized bed 53 side so that the fluidized air does not flow to the hopper portion 38 side.

Further, in the present embodiment, the amount of air blown from the opening 43 is used to control the degree of flow of the fluid medium 31 inside the hopper 38 to control the amount of heat absorbed by the boiler water pipes 35. As shown in FIG. 3, particularly in the case of a round furnace, the position where the opening 63 of the jet air of the pipe 62 penetrating the caster outer wall 61 is provided is divided into a plurality of areas along the circumference (for example, when divided into eight). , F1 to F8), a plurality of areas F1 to F8 are provided in the order of the numbers, and the additional air is ejected while balancing the flowing medium flowing position in the furnace circumferential direction.
The flow amount of the fluidized medium inside the plurality of hopper portions 64 may be controlled by the valve 65 to control the amount of heat absorbed by the boiler water pipes 66.

In addition to this embodiment, as shown in FIG. 4, a pipe 46 for jetting a weak fluidizing air, which is vertically opened toward the hopper 38 side, is provided on the inclined portion 28 of the caster outer wall 21. It may be provided separately. In this case, the fluidizing medium 31 is moved by the weak fluidizing air from the opening 47 of the pipe 46,
Although the wear of the group 35 of boiler water pipes due to 31 increases, the weak fluidized air increases the amount of heat absorbed by heat exchange with the group 35 of boiler water pipes, thereby improving the utilization efficiency of thermal energy. Therefore, taking into consideration the degree of wear of the group of boiler water pipes 35 and the degree of increase in the amount of heat absorption due to heat exchange, the boiler water pipes should be at a level that does not interfere.
If a small amount of fluidizing air is set with a certain sacrifice in wear of group 35, the utilization efficiency of thermal energy can be set well by this weak fluidizing air, and wear of boiler water pipe group 35 Can be suppressed to a level that does not hinder. 48 is a valve for adjusting the supply air volume.

Further, in the present embodiment, the piping direction of the boiler water pipes 35 is set to the direction perpendicular to the flowing direction of the fluid medium 31, but as shown in FIG. 5, the fluid medium 72 inside the heat recovery section 71 is used.
If the piping directions of the group of boiler water pipes 73 are the same with respect to the flow direction of, the flow medium 31 flows down and the opening 75 of the pipe 74
The wear of the boiler water pipe 73 group due to the movement of the fluidizing medium 72 due to the weak fluidized air from is also reduced.

[0018]

As described above, according to the present invention, the partition member for partitioning the heat-resistant outer wall inner peripheral portion so as to have the heat recovery portion is provided in the heat-resistant outer wall inner peripheral portion having a large upper volume. The fluidized gas jetting part, which is provided above the step part and forcibly recirculates the fluidized medium at the outlet part for communicating the bottom part of the heat recovery part and the combustion part between the step part and the partition member, to the combustion part In the case where the calorific value of the incineration product fluctuates well by providing the fluidizing gas amount control unit capable of controlling the supply amount of the fluidizing gas in the pipe portion connected to the fluidizing gas ejection unit, The furnace can be better controlled at a constant bed temperature, and energy can be saved by recovering and using the combustion energy of the incinerator, for example, recovering it as boiler steam instead of supplying cooling water to the floor. Can be Further, if the fluidizing gas is prevented from flowing to the heat recovery section side as much as possible, it is possible to obtain a variable heat transfer surface of the heat transfer tube group for in-layer temperature adjustment that causes less wear.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a partial configuration of a fluidized bed combustion furnace according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing a partial configuration of the furnace showing another embodiment of the installation position of the fluidizing gas injection part in the partial configuration of the fluidized bed combustion furnace of FIG.

FIG. 3 is a transverse cross-sectional view of a furnace in which the fluidized bed combustion furnace shown in FIG. 1 is a round type, and another embodiment for controlling the flow-down of the fluidized medium inside the hopper by the air blown out from the opening.

FIG. 4 is a vertical cross-sectional view showing a partial configuration of the furnace showing an embodiment in which a fluidized gas injection part is additionally provided in the partial configuration of the fluidized bed combustion furnace of FIG.

5 is a partial configuration of a furnace showing an embodiment in which a partial configuration of the fluidized bed combustion furnace of FIG. 4 is simplified and a piping direction of a boiler water pipe group is made to coincide with a flowing direction of a fluid medium. Vertical section view

FIG. 6 is a vertical sectional view showing the structure of a conventional fluidized bed combustion furnace.

[Explanation of symbols]

 21, 61 Caster outer wall 23 Steps 24, 46, 51, 62, 74 Pipes 26, 48, 65 Valve 27 Air supply device 31, 72 Fluid medium 33 Fluidized air 34 Combustion part 35, 66, 73 Boiler water pipe 36, 71 Heat recovery part 37 Partition wall 38, 64 Hopper part 43, 47, 52, 63, 75 Opening part 45 Outlet part 53 Fluidized bed

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location F23G 5/50 ZAB E 7815-3K (72) Inventor Junichi Sano 5 Nishikujo, Nishinoko-ku, Osaka-shi, Osaka 3-28, Hitachi Shipbuilding Co., Ltd. (72) Seiichi Nakai 5--3-28, Nishikujo Nishikonohana-ku, Osaka City, Osaka Prefecture Hitachi Shipbuilding Co., Ltd.

Claims (1)

[Claims] 1. A combusting section in which a fluidizing gas is supplied to a fluidized medium to fluidize the fluidized medium and at the same time a combustion product is supplied and burned, and a fluidized medium flowing from the combusting section through a heat transfer tube group. In a fluidized bed combustion furnace having a heat recovery unit that absorbs heat to control the bed temperature, a step portion having a large upper volume is provided on the heat-resistant outer wall inner peripheral portion, and the heat-resistant outer wall inner peripheral portion A partition member for partitioning the heat recovery section is provided above the step section, and an outlet section for communicating the bottom section of the heat recovery section and the combustion section is provided between the step section and the partition member. A fluidizing gas jetting portion for forcibly refluxing the fluidized medium of the outlet portion to the combustion portion side is provided in the inner peripheral portion of the heat resistant outer wall, and the supply amount of the fluidizing gas is supplied to the pipe portion connected to the fluidizing gas jetting portion. A fluidized bed combustion furnace provided with a controllable fluidized gas amount control member.