JP4556058B2 - Internal protection structure in exhaust gas duct - Google Patents

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 for 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 highly adherent dust, and 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.

The present invention solves the above-mentioned problem, keeps the slit width constant against thermal expansion, and the cooling air supplied from the air supply pipe to the ventilation chamber hits the in-chamber guide plate arranged in a slanting direction so that the inside of the ventilation chamber is circumferential. It is an object of the present invention to provide an inner surface protection structure in an exhaust gas duct that can form a flow and a swirl flow to prevent adhesion of dust and corrosion of the duct.

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;
Ri Do and a plurality of air supply pipe which is connected in the circumferential direction at predetermined intervals on the outer circumferential surface of the chamber, an annular slit portion is provided for along the duct inside surface blowing cooling air between the da transfected body and the chamber In the duct unit
The plurality of air supply pipes are connected to the outer peripheral surface of the ventilation chamber in the radial direction, and in the ventilation chamber, chamber guide plates are respectively arranged in an inclined manner with respect to the length direction of the air supply pipe. It is characterized by.

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

A plurality of slits in the guide plate in the circumferential direction at predetermined intervals in the slit portion has preferably be provided inclined relative to the duct length.

  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.

The plurality of air supply pipes are connected to the outer peripheral surface of the ventilation chamber in the radial direction, and in the ventilation chamber, chamber guide plates are respectively arranged in an inclined manner with respect to the length direction of the air supply pipe at the outlet of each supply pipe. Therefore, the cooling air supplied from the air supply pipe to the ventilation chamber strikes the in-chamber guide plate arranged in an inclined manner and flows in the circumferential direction in the ventilation chamber to form a swirling flow. Next, the cooling air ascends through the slit and is blown along the inner surface of the duct.
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, examples of the present invention will be given in order to specifically explain the present invention.

Reference 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 main body (1) (1 ′) through which exhaust gas passes and annular outer surfaces provided on the outer surfaces of the lower ends of the duct main bodies (1) and (1 ′). The air swirl chamber (2) and a plurality of air supply pipes (3) connected in a tangential direction 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 portion (1′a) of the lower-diameter lower duct body (1 ′) is concentrically arranged in the lower end portion (1a) of the large-diameter upper duct body (1). The upper and lower duct bodies (1) (1 ′) are connected so that an annular slit (5) is formed from the upper part and the upper end. An annular air swirl chamber (2) is provided over the outer surface of the lower end portion of the upper duct body (1) and the outer surface of the upper end portion of the lower duct body (1 '). A plurality of air supply pipes (3) are connected to the outer peripheral surface of each ventilation chamber (2) in a substantially tangential direction. 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 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 on the upper duct unit (4), and an annular air swirl chamber (2), a plurality of air supply pipes (3), and an annular slit (5) are connected to this connecting portion in the same manner as described above. ) Is provided.

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

  The cooling air is supplied from the plurality of air supply pipes (3) to the annular air swirling chamber (2) in the close contact direction, and forms a swirling 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 that 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 multiple duct units in this way, the temperature and supply amount of 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, and the exhaust gas temperature on the downstream side can be adjusted. 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.

Reference example 2
FIG. 4 shows another example of an exhaust gas duct.

  In this example, the lower end connecting portions of the upper and lower duct bodies (1) (1 ') and the curved duct (7) that constitute the exhaust gas duct have a cone cylinder shape that increases in diameter as it goes downward. This is to prevent the duct diameter from becoming large.

The duct configuration and operation are the same as in Reference Example 1 .

Example 1
Figure 5 and Figure 6 shows an example 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 in an inclined manner with respect to the length direction of the supply pipe (3) at each supply pipe outlet.

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. Next, the cooling air ascends through the slit portion (5) and is blown along the inner surface of the duct. At that 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.

4 is a vertical sectional view showing an exhaust gas duct of Reference 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. 5 is a vertical sectional view showing an exhaust gas duct of Reference Example 2. FIG. 1 is a cross-sectional view showing an annular air swirl chamber of Example 1. FIG. It is a vertical sectional view showing a connecting portion of the upper and lower duct units.

(1): Upper duct body (1a): Lower end part (1 ′): Lower duct body (1′a): Upper end part (2): Air swirl chamber (3): Supply pipe (4): Upper duct unit ( 4 ′): lower duct unit (5): slit part (6): exhaust gas outlet (7): curved duct (8): protrusion (9): guide plate in slit (10): guide plate in 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;
Ri Do and a plurality of air supply pipe which is connected in the circumferential direction at predetermined intervals on the outer circumferential surface of the chamber, an annular slit portion is provided for along the duct inside surface blowing cooling air between the da transfected body and the chamber In the duct unit
The plurality of air supply pipes are connected to the outer peripheral surface of the ventilation chamber in the radial direction, and in the ventilation chamber, chamber guide plates are respectively arranged in an inclined manner with respect to the length direction of the air supply pipe. An internal protective structure for an exhaust gas duct characterized by   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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