JP2006234260A - Inner face protecting structure in exhaust gas duct - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inner face protecting structure in an exhaust gas duct capable of keeping a constant slit width to thermal expansion and preventing attachment of dust and corrosion of the duct. <P>SOLUTION: This inner face protecting structure is composed of duct main bodies 1, 1' through which an exhaust gas passes, circular air swirling chambers 2 mounted on outer faces of lower end portions of the duct main bodies, and a plurality of air supply pipes 3 connected with outer peripheral faces of the chambers 2 at prescribed intervals in the circumferential direction, in duct units 4, 4'. Circular slit portions 5 are respectively formed between the duct main body and the chamber to supply the cooling air along an inner face of the duct. Preferably, the plurality of duct units are stacked. A plurality of slit guide plates 9 are mounted in the slit portions at prescribed intervals in the circumferential direction in a state of being inclined in the longitudinal direction of the duct. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exhaust gas duct provided at an exhaust gas outlet of a melting furnace or the like. More specifically, the present invention relates to a structure that forms a protective layer of cooling air on the inner surface of the duct, thereby preventing corrosion and dust adhesion on the inner surface. .

  In the ash melting furnace, the high-temperature gas generated when melting ash flows in the exhaust gas duct in a state containing dust with strong adhesion, and therefore there is a problem that the inner surface of the duct is corroded or dust is attached.

  Conventionally, as an exhaust gas duct for solving such problems, the duct is constituted by a double cylinder of an inner cylinder and an outer cylinder, and the cooling gas introduced between the double cylinders is placed on the inner peripheral surface of the inner cylinder. A structure in which slit-like blowing holes are formed along the exhaust gas flow direction along the exhaust gas flow direction is known (see Patent Document 1).

A slit is provided between the inner cylinder and the outer cylinder for injecting gas along the inner circumferential surface of the inner cylinder, with an outer cylinder surrounding the inner cylinder with a space outside the cylindrical inner cylinder. There is also known a structure in which a nozzle having a nozzle hole is provided, and cooling gas introduced into the space between the inner cylinder and the outer cylinder is blown from the nozzle hole along the inner peripheral surface of the inner cylinder ( Patent Document 2).
JP 2000-104916 A JP 2002-357314 A

  However, in the structure of Patent Document 1, as shown in FIG. 1, a plurality of vertically stacked duct units are connected by a flange connection, so that a slit (blowing hole) can be provided to the end. In addition, there is no slit at the joint between the units, and cooling air cannot be ejected.

  Moreover, in the structure of patent document 2, since the slit (blowing nozzle) was provided in the longitudinal direction of the exhaust gas duct, there was a problem that the slit width changed due to the expansion of the duct due to heat.

  An object of the present invention is to solve the above-mentioned problems, and to provide an inner surface protection structure in an exhaust gas duct that can keep a slit width constant against thermal expansion and can prevent dust adhesion and duct corrosion. .

The inner surface protection structure in the exhaust gas duct according to the present invention is:
A duct body for passing exhaust gas;
An annular air swirl chamber provided on the outer surface of the lower end of the duct body;
In the duct unit consisting of a plurality of air supply pipes connected to the outer peripheral surface of the chamber at a predetermined interval in the circumferential direction,
An annular slit for blowing cooling air along the inner surface of the duct is provided between the duct body and the chamber.

  It is preferable that a plurality of duct units are stacked.

  It is preferable that a plurality of guide plates in the slit are provided in the slit portion at predetermined intervals in the circumferential direction so as to be inclined with respect to the duct length direction.

  The plurality of air supply pipes are preferably connected to the outer peripheral surface of the chamber in a substantially tangential direction. The term “substantially tangential direction” means that it may be inclined ± 30 degrees around the mathematical tangential direction. Thereby, the cooling air introduced in the tangential direction from the supply pipe into the chamber forms a swirling flow in the chamber. Next, since the cooling air is blown into the duct through the slit portion in a swirling state, a stable protective layer can be formed.

  If it is difficult to connect the air supply pipe to the outer peripheral surface of the chamber in the tangential direction due to space limitations of the duct installation, connect multiple air supply pipes to the outer peripheral surface of the ventilation chamber in the radial direction, A guide plate in the chamber may be disposed at each outlet of each of the supply pipes so as to be inclined with respect to the length direction of the supply pipe. This also allows the cooling air to swirl within the chamber.

  According to the invention which concerns on Claim 1, even if there exists a temperature change, the width | variety of a slit part does not change. Therefore, cooling air that has entered the air swirl chamber from a plurality of air supply pipes is blown into the duct through a slit having a uniform width, thereby forming a protective layer for the cooling air on the inner surface of the duct, and covering the entire inner surface of the duct with the same protective layer. Thus, corrosion and dust adhesion on the inner surface can be reliably prevented.

  According to the invention which concerns on Claim 2, the protective layer mentioned above can be formed for every duct unit by stacking a plurality of duct units. Thus, the temperature and supply amount of the cooling air can be adjusted so that the exhaust gas is lowered to a predetermined temperature without contacting the inner surface of the duct, and the downstream exhaust gas temperature can be controlled to an appropriate value. Further, the cooling air protective layer is not interrupted between the duct units.

  According to the invention of claim 3, by providing a plurality of guide plates in the slit in the slit portion at predetermined intervals in the circumferential direction, the cooling air blown along the inner surface of the duct is It can be turned spirally in the direction.

Next, in order to explain the present invention specifically, some examples of the present invention will be given. Example 1
First, the configuration of the exhaust gas duct will be described.

  1-3, the exhaust gas duct is composed of a vertical duct composed of duct units (4) and (4 ') stacked in two upper and lower stages, and a curved duct (7) connected to the upper duct unit (4). ing.

  The upper and lower duct units (4) and (4 ') are respectively formed in a cylindrical duct body (1) (1') through which exhaust gas passes and an annular shape provided on the outer surface of the lower end of the duct body (1) (1 '). The air swirl chamber (2) and a plurality of air supply pipes (3) connected tangentially to the outer peripheral surface of the chamber (2).

  In each duct unit (4) (4 ′), an annular slit (5) for blowing cooling air is provided between the duct body (1) and the chamber (2).

More specifically, the upper end (1'a) of the small-diameter lower duct body (1 ') is concentrically arranged in the lower end (1a) of the large-diameter upper duct body (1), and thereby the lower end The upper and lower duct bodies (1) (1 ′) are connected so that an annular slit portion (5) is formed from the upper portion and the upper end portion. An annular air swirl chamber (2) is provided across the outer surface of the lower end of the upper duct body (1) and the outer surface of the upper end of the lower duct body (1 ′). A plurality of air supply pipes (3) are connected in a substantially tangential direction to the outer peripheral surface of each ventilation chamber (2). Here, the substantially tangential direction means that it may be inclined by ± 30 degrees around the mathematical tangential direction as indicated by a broken line in FIG. The air supply pipe (3) is basically connected in a tangential direction to the outer peripheral surface of the ventilation chamber (2), but is appropriately determined within a range of ± 30 degrees from the tangential direction. The plurality of supply pipes (3) are provided at predetermined intervals in the circumferential direction of the ventilation chamber (2). The lower end of the slit portion (5) communicates with the air swirl chamber (2).

  A curved duct (7) is connected to the upper duct unit (4), and an annular air swirling chamber (2), a plurality of air supply pipes (3), and an annular slit (5 ) Is provided.

  The lower duct unit (4 ′) is connected to the exhaust gas outlet (6) of the furnace, and this connecting part is also connected to the annular air swirl chamber (2), the plurality of air supply pipes (3), and the annular slit part (as described above). 5) is provided. (8) is the outlet of the exhaust gas outlet (6) of the furnace.

  In each slit portion (5), a plurality of (for example, 4 to 24) in-slit guide plates (9) are provided at predetermined intervals in the circumferential direction so as to be inclined with respect to the duct length direction.

  The exhaust gas duct having such a structure operates as follows.

  Cooling air is supplied from a plurality of air supply pipes (3) to the annular air swirl chamber (2) in the close-contact direction, and forms a swirl flow in the chamber (2). Next, the cooling air ascends through the slit portion (5) and is blown along the inner surface of the duct. At this time, the cooling air is spirally swung around the inner surface of the duct in a circumferential direction by a plurality of slit guide plates (9). It is done.

  By stacking the duct units in multiple stages in this way, the temperature and supply amount of the cooling air can be adjusted so that the exhaust gas is lowered to a predetermined temperature without contacting the inner surface of the duct for each duct unit. It can be controlled to an appropriate value. As a result, the gas temperature passing through the downstream curved duct (7) can be controlled to an appropriate value.

Example 2
FIG. 4 shows a modification of the exhaust gas duct according to the present invention.

  In this example, the upper and lower duct bodies (1) (1 ') constituting the exhaust gas duct and the lower end connecting portion of the curved duct (7) both have a cone cylinder shape with a diameter increasing toward the bottom. This is to prevent the duct diameter from becoming large.

  The duct configuration and operation are the same as those in the first embodiment.

Example 3
5 and 6 show another modification of the exhaust gas duct according to the present invention.

  In this example, the plurality of air supply pipes (3) are connected in the radial direction to the outer peripheral surface of the ventilation chamber (2). In the ventilation chamber (2), an in-chamber guide plate (10) is disposed at an outlet portion of each supply pipe so as to be inclined with respect to the length direction of the supply pipe (3).

  In this configuration, the cooling air supplied from the air supply pipe (3) to the ventilation chamber (2) hits the in-chamber guide plate (10) inclined and flows in the ventilation chamber (2) in the circumferential direction to generate a swirling flow. Form.

1 is a vertical sectional view showing an exhaust gas duct of Example 1. FIG. It is sectional drawing which shows the cyclic | annular air swirl chamber which follows the II-II line | wire in FIG. It is a vertical sectional view showing a connecting portion of the upper and lower duct units. 4 is a vertical sectional view showing an exhaust gas duct of Example 2. FIG. 6 is a cross-sectional view showing an annular air swirl chamber of Example 3. FIG. It is a vertical sectional view showing a connecting portion of the upper and lower duct units.

Explanation of symbols

(1): Upper duct body
(1a): Lower end
(1 '): Lower duct body
(1'a): Upper end
(2): Air swirl chamber
(3): Supply pipe
(4): Upper duct unit
(4 '): Lower duct unit
(5): Slit
(6): Exhaust gas outlet
(7): Curved duct
(8): Mouth
(9): Guide plate in the slit
(10): Guide plate in the chamber

Claims (3)

A duct body for passing exhaust gas;
An annular air swirl chamber provided on the outer surface of the lower end of the duct body;
In the duct unit consisting of a plurality of air supply pipes connected to the outer peripheral surface of the chamber at a predetermined interval in the circumferential direction,
An inner surface protection structure for an exhaust gas duct, wherein an annular slit portion for blowing cooling air along the inner surface of the duct is provided between the duct body and the chamber.   The inner surface protection structure for an exhaust gas duct according to claim 1, wherein a plurality of duct units are stacked. The inner surface protection structure for an exhaust gas duct according to claim 1 or 2, wherein a plurality of guide plates in the slit are provided in the slit portion at predetermined intervals in the circumferential direction so as to be inclined with respect to the duct length direction.

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