JPH1182966A - Flowing medium separating device in circulating fluidized bed type furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease or restrict an increase in an occupied sectional area and an occupied furnace height and at the same time facilitate its maintenance work. SOLUTION: An arcuate wall surface 34 is formed from a communicating fluidized bed type furnace 38 at an upper part of a riser 1 in a downward direction in order to separate flowing medium from combustion gas under utilization of inertia of the combustion gas discharged from the riser 1 and a gravity acted upon the flowing medium. The combustion gas is flowed along the wall surface and fed into the furnace and at the same time a curved gas flow passage 33 curved in a direction branched from an inertia force, and a gravity acted against the flowing medium in the combustion gas is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized bed for separating a fluid medium contained in a combustion gas from a combustion gas in a circulating fluidized bed furnace used for various types of fuel boilers such as a waste incinerator and coal. The present invention relates to improvement of a medium separation device.

[0002]

2. Description of the Related Art In recent years, a circulating fluidized bed furnace has a stable combustion state with respect to fluctuations in the properties and loads of combustion products, compared with conventional bubble fluidized bed furnaces, and is suitable for mixed incineration of various types of combustion products. It is also suitable for waste that contains many components that generate low-melting compounds such as phosphorus, sodium, and potassium. Now being used.

Here, an outline of a general circulating fluidized bed furnace according to the present invention will be exemplified with reference to FIG. The circulating fluidized bed furnace includes a riser 1 which is a furnace body for drying, pyrolyzing, and burning waste and fuel, and a fluid medium separating device 20 for separating a fluid medium led out along with the combustion gas from an upper portion of the riser 1, And a downcomer 2 serving as a fluid medium return pipe for circulating the separated fluid medium to a lower portion of the riser 1.
1 is comprised. An air supply port 13, an auxiliary fuel supply port 14, and a combustion product supply port 15 are provided below the riser 1, and the air for combustion and flow, the required auxiliary fuel and the target Wastes and the like are supplied, and the supplied wastes and the like are burnt while being dried and thermally decomposed while flowing in a mixed state with a fluid medium.

[0004] The combustion gas generated in the riser 1 is discharged from a combustion gas discharge port 19 above the riser 1, and is guided to an adjacent fluidized medium separator 20. Incombustibles and the like that cannot be processed by the riser 1 are discharged from the lower discharge port 18 in a timely manner. The auxiliary fuel supply port 14 supplies a required auxiliary fuel when the calorific value is small and the temperature in the furnace cannot be maintained at an appropriate temperature.

[0005] Next, the fluidized medium separating device 2 is usually provided with a device shown in FIG.
The cyclone is formed from a cyclone in which a cone is joined to a lower portion of a cylinder, and a refractory is provided inside the cyclone so as not to hinder the introduction of high-temperature combustion gas. Here, since the induced combustion gas is guided in the tangential direction of the inner wall of the cylinder of the cyclone, it forms a swirling flow and is sucked into the central exhaust gas passage 23, and the exhaust gas port 25 is formed.
Is discharged from At the same time, the fluid medium containing the combustion gas gathers on the inner wall side of the cylinder due to the centrifugal force generated by the swirling flow, is separated from the discharged exhaust gas, falls by its own weight, and flows downward. It will be collected in the medium retention zone 22.

[0006] The lower end of the fluid medium retention zone 22
The recovered fluid medium which is in communication with the riser 1 is maintained in a fluidized state by air supplied from a plurality of control air ports 24 disposed at the lower end thereof, and is supplied to the riser 1 by reflux in an appropriate amount. It is controlled as follows. Thus, in this circulating fluidized bed furnace, the fluid medium that improves the heat treatment efficiency is recovered, circulated, and used. In addition, as a fluid medium for such an application, for example, particles such as silica sand and alumina having a particle size of about 0.3 to 0.8 mm are preferably used.

However, in the case of such a circulating fluidized-bed furnace, as the size of the circulating fluidized bed furnace increases, the cyclone is inevitably increased in size, and the occupied sectional area and occupied furnace height are significantly increased. There was a problem. For example, when the occupied cross section and the occupied furnace height of the facility are illustrated in the case of a sewage sludge incinerator, the occupied cross section of a circulating fluidized bed furnace having a sewage sludge treatment capacity of 300 tons / day is about 30 m ² , The furnace height is as large as 18 m, especially the cyclone portion occupies about 16.5 m ² , occupying about 12 m of the occupied furnace height, and the conventional bubble fluidized bed furnace occupies about 62 m ² , Since the proprietary furnace height is 15m,
A sufficient size reduction effect could not be obtained.

Further, since the size of the incinerator is increased in this way, the construction cost is increased, or after the construction, the running cost such as the periodic repair for the wear inside the cyclone is increased, or the incinerator is required for a long period of time for the periodic repair. There was a problem inherent to the conventional cyclone that the operation had to be stopped. In particular, in the conventional cyclone, the flowing medium is spirally flowing to a specific part of the inner wall of the cylinder and spirally flows, so only that part is extremely worn. Repair was not possible and the entire cyclone had to be replaced or the entire refractory had to be rebuilt.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to improve the structure of a cyclone for separating a flowing medium in a combustion gas to reduce the size. A circulating fluidized bed furnace that adopts a separation mechanism that can reduce the occupied cross-sectional area and the occupied furnace height or suppress the increase in the occupied furnace height, reduce the wear of its inner wall, and facilitate maintenance. The present invention provides a fluidized medium separator.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a fluidized medium separation device according to the present invention directs combustion gas discharged from a riser to a fluidized medium separation zone adjacent to the riser. In a circulating fluidized-bed furnace in which a fluidized medium contained in a combustion gas is separated and exhausted as a separated combustion gas, and the separated fluidized medium is returned to the riser, the inertia and the fluidized medium of the combustion gas discharged from the riser In order to separate the flowing medium from the combustion gas by using the gravity acting on the inner wall of the separation zone, an arc-shaped wall is formed on the inner wall of the separation zone, and the combustion gas is introduced from above to below along the arc-shaped wall. In addition, a curved gas flow path curved in a direction branched from the direction of inertia and gravity acting on the fluid medium in the combustion gas is formed.

In the present invention, a downcomer (fluid medium return pipe) for guiding the fluid medium separated by inertia and gravity to a lower fluid medium retention zone is provided in the fluid medium separation zone, The separated combustion gas exhaust passage communicating with the arc-shaped wall is opened and arranged on the wall surface of the separation zone facing the arc-shaped wall surface to form the curved gas passage, and the separated combustion gas is exhausted from the side wall of the fluidized medium separator. It can be embodied in the form described above.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a fluidized-medium separating apparatus for a circulating fluidized-bed furnace according to the present invention will be described with reference to FIG. In FIG. 1, FIG. 1 (a) is a diagram showing a cross section taken along line a-a of FIG. 1 (b), and FIG. FIG. In this circulating fluidized bed furnace, although there is a remarkable difference in the structure of the fluidized medium separation zone 31, its basic structure is similar to the structure of the conventional circulating fluidized bed furnace described above.

A feature of the present invention is that, in the fluid medium separation zone 31 communicating with the riser 1, the flow path of the combustion gas introduced into the fluid medium separation zone 31 is curved from the upper side to the lower side. Is formed in a curved gas flow path 33 that is curved in a branched direction different from the inertial direction of the flowing medium toward. In order to do so, the wall surface constituting the fluidized medium separation zone 31 is partially formed in an arc shape outward, and the combustion gas is guided from above to below along the arc wall surface 34. It is arranged as follows. With this configuration, the fluid medium gathers along this arc-shaped wall surface 34 due to centrifugal force,
Separation from combustion gas is performed more effectively.

In FIG. 1, the upper end of the riser 1 and the upper end of the fluid medium separation zone 31 are connected by a communication flow path 38. After narrowing the cross-sectional area of the riser 1 and accelerating the velocity of the combustion gas induced from the riser 1,
If the curved gas flow path 33 is guided along the arc-shaped wall surface 34, the flowing medium advances downward along the arc-shaped wall surface 34 by the imparted inertia, while the combustion gas portion is The fluid is sucked in a branching direction different from the inertial direction, flows sharply in a curved manner, and the flowing medium and the combustion gas are separated. In this case, for example,
The speed of the combustion gas is controlled to 10 to 20
By accelerating to m / sec and setting the radius of curvature of the arcuate wall surface 34 to a range of 2 to 5 times the height of the communication channel 38, it was found that the fluid medium could be reliably separated from the combustion gas. .

As described above, in the curved gas flow path 33, while the fluid medium in the gas is pressed against the arc-shaped wall surface 34 by the centrifugal force, the inertia from the upper side to the lower side is imparted. While gathering and falling downward from the lower end, as shown in FIG.
If the downcomer 35 communicating with the lower fluid medium retaining zone 32 is provided continuously to the arc-shaped wall surface 34 of the separation zone 31, the separated fluid medium flows through the lower fluid medium retaining It is guided to the zone 32, and the reflux of the fluid medium is performed smoothly.

At the same time, in order to discharge the combustion gas from which the fluid medium has been separated, a separated combustion gas exhaust passage 36 communicating with the outside faces the arc-shaped wall surface of the inner side wall surface of the fluid medium separation zone 31. If the combustion gas is exhausted from the side wall of the fluidized medium separation zone 31 as shown in FIG.
While the combustion gas forms a curved flow, the inertized flow medium can be effectively separated.

As described above, according to the present invention, a curved gas flow path that curves from above and goes toward the opening is formed by guiding the combustion gas along the arc-shaped wall surface formed in the fluidized medium separation zone. While the fluid medium in the combustion gas is pressed against the arc-shaped wall surface by centrifugal force and imparts inertia from above to below to separate the combustion gas and the fluid medium, the spiral shape described above is used. Unlike the case of the turning cyclone, no horizontal space is required for turning, so that the occupied cross-sectional area can be reduced.

Further, according to the present invention, the height of the fluidized medium separator itself can be kept lower than that of the conventional cyclone.
Since the separated combustion gas exhaust passage communicating with the outside is provided to be opened on the side wall surface of the fluidized medium separation zone, the combustion gas separated from the fluidized medium can be led out from the opening on the side wall surface. Unlike the above-described cyclone in which the exhaust gas port projects upward, the height of the furnace does not need to be set unnecessarily high, so that the occupied furnace height can be suppressed.

Further, in the fluid medium separation device, a part of the wall surface is formed into an arc-shaped wall surface, and the combustion gas flows along the wall surface. Therefore, the abrasion caused thereby mainly occurs on the arc-shaped wall surface. Will be. In the conventional cyclone, the fluid medium flows spirally to a specific part of the inner wall of the cylinder, so that only that part is extremely worn.However, in the fluid medium separator of the present invention, the arc-shaped wall is uniform. Wear out. Therefore, when using the same refractory,
The operating time of the furnace before repair of the fluidized medium separator is required can be increased. In addition, since the arc-shaped wall surface is mainly worn, the separation device can be divided so that only this portion can be replaced or repaired, and the repair cost can be greatly reduced. Furthermore, because it is a shape that can be easily constructed with fixed refractories such as bricks, which was difficult with the conventional cylindrical cyclone, it is more durable, the frequency of periodic repairs is less, and the maintenance is easier. There are many advantages, such as:

[0020]

EXAMPLES As examples, 300 tons / day scale sewage sludge incinerators using a conventional bubble fluidized bed furnace, a circulating fluidized bed furnace, and a circulating fluidized bed furnace equipped with a fluidized medium separator of the present invention were used. Each furnace size was estimated and compared.
FIGS. 2, 3 and 4 show, on the same scale, illustrations of a bubble fluidized bed furnace (FIG. 2), a conventional circulating fluidized bed furnace (FIG. 3), and a circulating fluidized bed furnace of the present invention (FIG. 4) based on the calculation results. It is shown and compared. Table 1 below summarizes representative numerical values.

[0021]

[Table 1] Note "Ratio": The ratio when the value of a conventional bubble fluidized bed furnace is set to 1.

According to Table 1, although the conventional circulating fluidized bed furnace has a smaller occupied cross-sectional area than the bubble fluidized bed furnace, the furnace height, It can be seen that the furnace width was rather large, and sufficient space saving was not achieved. On the other hand, the circulating fluidized-bed incinerator using the fluidized-medium separation device of the present invention has the same occupied furnace height as the bubble fluidized-bed furnace, but the occupied cross-sectional area and the furnace width are considerably reduced. You can see what you can do. In particular, it is understood that the occupied cross-sectional area can be reduced to about 1/3 as in this embodiment, and it can be seen that the effect of the fluidized medium separator of the present invention is remarkable.

[0023]

As described above, the fluidized-medium separation device for a circulating fluidized-bed furnace according to the present invention employs a compact structure for separating a fluidized medium from exhaust gas, as described above.
Even when the furnace is scaled up, it is possible to reduce or increase the occupied cross-sectional area and occupied furnace height, effectively utilize the space, and the construction cost becomes extremely advantageous.
In addition, the structure has an excellent effect that the structure is excellent in durability and easy to maintain, so that it is advantageous in running cost. Therefore, the present invention has an extremely high industrial value as a fluidized medium separator for a circulating fluidized bed furnace which solves the conventional problems.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a circulating fluidized bed furnace for explaining an embodiment of the present invention.

FIG. 2 is a schematic diagram of a conventional bubble fluidized bed furnace for comparing sizes. (A) is an arrow sectional view, (b) is a front sectional view.

FIG. 3 is a schematic diagram of a conventional circulating fluidized bed furnace for comparing sizes. (A) is an arrow sectional view, (b) is a front sectional view.

FIG. 4 is a schematic diagram of an example circulating fluidized bed furnace for comparing sizes. (A) is an arrow sectional view, (b) is a front sectional view,
(C) is a side view.

FIG. 5 is a sectional illustration for explaining a conventional circulating fluidized bed furnace.

[Explanation of symbols]

1 Riser, 31 Fluid medium separation zone, 32 Fluid medium retention zone, 33 Curved gas flow path, 34 Arc-shaped wall surface, 35 Downcomer, 36 Separated combustion gas exhaust flow path, 38 Communication flow path.

Claims (2)

[Claims] 1. Directing a combustion gas discharged from a riser to a fluidized medium separation zone adjacent to the riser,
In the circulating fluidized-bed furnace in which the fluidized medium contained in the combustion gas is separated and discharged as a separated combustion gas, and the separated fluidized medium is returned to the riser, the inertia and the fluidized medium of the combustion gas discharged from the riser are reduced. In order to separate the fluid medium from the combustion gas using working gravity, an arc-shaped wall surface is formed outward on the inner wall of the separation zone, and the combustion gas is introduced from above to below along the arc-shaped wall surface. A fluidized medium separator for a circulating fluidized bed furnace, wherein a curved gas flow path curved in a direction branched from a direction of inertia and gravity acting on the fluidized medium in the combustion gas is formed. 2. A separated combustion gas exhaust passage is opened and arranged on a wall surface of a separation zone opposed to an arc-shaped wall surface to form the curved gas passage, and separate combustion gas is separated from a side wall of a fluidized medium separator. The fluidized-medium separation device for a circulating fluidized-bed furnace according to claim 1, wherein the fluid is exhausted.