JP4868924B2 - Chimney and waste heat recovery boiler - Google Patents

Description

   The present invention relates to an exhaust heat recovery boiler of a combined power plant combining a gas turbine and an exhaust heat recovery boiler (HRSG), and a chimney used for the exhaust heat recovery boiler.

  A combined power plant combined with a gas turbine exhaust heat recovery boiler has higher power generation efficiency than other thermal power plants, and natural gas is often used as fuel, and there is little generation of sulfur oxide and soot, It is attracting attention as a power plant with a high future with a low burden of exhaust gas purification treatment.

  FIG. 10 shows a schematic diagram of the device configuration of a conventional combined power plant. Exhaust gas from the gas turbine 1 is guided to the exhaust heat recovery boiler 2. In the exhaust heat recovery boiler 2, heat is recovered from the exhaust gas by a heat transfer tube group such as the economizer 3 and the evaporator tube 4 to generate steam. The steam is superheated by the superheater 5, and the steam is used in a factory or the like through the main steam pipe 8 or supplied to a steam turbine for power generation.

Further, since the exhaust gas contains nitrogen oxides (hereinafter abbreviated as NOx), a denitration device 6 is incorporated in the exhaust heat recovery boiler 2 and ammonia (NH ₃ ) is injected into the exhaust gas. NOx removal is performed. On the other hand, when oils, for example, A heavy oil is used as fuel for the gas turbine 1, the exhaust gas of the gas turbine 1 contains a large amount of sulfur oxide (hereinafter abbreviated as SOx) due to the sulfur content in the fuel. . In this case, acidic ammonium sulfate is generated in a region where the gas temperature is 220 ° C. to 150 ° C. (corresponding to the region of the economizer 3 in FIG. 10) due to a chemical reaction between ammonia and SOx injected for NOx removal. It adheres to the heat transfer tube group. This acidic ammonium sulfate is corrosive and rusts the heat transfer tube group. Further, the acidic ammonium sulfate becomes powdery when cooled, but when the exhaust heat recovery boiler 2 is stopped and cooled, the acidic ammonium sulfate becomes powdery in the exhaust heat recovery boiler 2. When the gas turbine 1 is started in such a state, rust and acidic ammonium sulfate are conveyed to the gas and scattered from the chimney 9 (height is about 50 to 80 m) at the outlet of the exhaust heat recovery boiler 2, or rust and There is a risk of soiling or corroding surrounding equipment with acid ammonium sulfate. Moreover, since the dust contained in the exhaust gas adheres to the heat transfer tube group, when the exhaust heat recovery boiler 2 is restarted, it may be scattered from the chimney 9 together with rust and acidic ammonium sulfate into the atmosphere.

  In the invention described in Patent Document 1, powdered acidic ammonium sulfate, rust and dust are prevented from scattering from the chimney 9 at the outlet of the exhaust heat recovery boiler 2 due to restart of the gas turbine 1 as shown in FIG. For this purpose, a net-like damper 11 and a plate-like damper 10 are installed in the chimney 9 on the gas upstream side (lower part of the chimney 9 in FIG. 1). FIG. 10B shows a plate-like damper 10, and FIG. 10C shows a perspective view of the net-like damper 11.

In the exhaust heat recovery boiler 2 shown in FIG. 10A, the chimney 9 is closed with the plate-like damper 10 in a state where the combined power plant is operated for a specified time and then stopped, and at the same time the gas turbine 1 is also stopped. Then, the worker enters the chimney 9 and uses the damper 10 as a scaffold to remove acid ammonium sulfate, rust, and dust attached to the mesh damper 11.
JP 2005-241075 A

The invention described in Patent Document 1 has a drawback that the structure of the mesh damper 11 is somewhat complicated, and it takes time to remove dust and the like adhering to the gaps of the metal mesh.
SUMMARY OF THE INVENTION An object of the present invention is to provide a chimney having a relatively simple structure and easy-to-handle removal means such as dust, and an exhaust heat recovery boiler using the chimney.

The problems of the present invention are solved by the following means.
That is, the invention according to claim 1 is provided with a dust trapping device in which a plurality of wire mesh frames are detachably mounted on a support beam in an upper part of a damper in a vertically-directed chimney for exhaust gas having a damper inside. It is a chimney.

  According to a second aspect of the present invention, there is provided a wire netting type dust trapping device, wherein a vertical beam portion having a plane in the vertical direction and a horizontal plane at the lower end of the vertical beam portion are arranged in parallel in the horizontal cross-sectional direction of the chimney. The chimney according to claim 1, comprising a support beam having a T-shaped cross section comprising a horizontal beam portion and a detachable wire mesh frame placed on the horizontal beam portion of the support beam.

A third aspect of the present invention is the chimney according to the first or second aspect, wherein the wire netting type dust trapping device is provided 0.5 m to 2.5 m above the damper.
According to a fourth aspect of the present invention, in the exhaust heat recovery boiler in which a large number of heat transfer tube groups and a denitration device are arranged in a duct through which the combustion exhaust gas from the gas turbine flows, the gas turbine combustion exhaust gas after heat exchange in the heat transfer tube group is It is a waste heat recovery boiler which uses the chimney in any one of Claim 1 to 3 as a chimney discharged | emitted in air | atmosphere.

According to the first aspect of the present invention, even in a chimney in which air dust such as dust is concerned, the wire mesh type dust trapping device has a structure in which a plurality of wire mesh frames that can be easily attached and detached are placed on the support beam. It is possible to easily prevent the soot and the like adhering to the air from being scattered into the atmosphere by removing the wire mesh frame from the support beam.
According to the second aspect of the present invention, in addition to the effect of the first aspect of the invention, the metal mesh frame is merely detachably mounted on the horizontal beam portion of the support beam. Can be placed on the support beam.

According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, an operator can easily attach and detach the wire mesh frame on the damper.
According to the fourth aspect of the present invention, it is possible to prevent smoke and the like from being scattered in the atmosphere when the operation of the exhaust heat recovery boiler is resumed.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the overall structure of the chimney at the outlet of the exhaust heat recovery boiler of this embodiment.
The exhaust heat recovery boiler outlet exhaust gas G is received in the lower part of the chimney 9 at the outlet of the exhaust heat recovery boiler 2, and the exhaust gas G is released into the atmosphere from the outlet of the upper chimney 9. A damper 10 is installed on the way for heat retention when the exhaust heat recovery boiler 2 is stopped and for draining rain from the top of the chimney 9. A wire net type dust trap 12 is provided on the upper portion of the damper 10. If this dust trap device 12 is always installed, the flow resistance of the exhaust gas increases due to dirt during long-term operation and leads to a decrease in the operating efficiency of the exhaust heat recovery boiler 2, so the always installed portion is kept to the minimum necessary.

  Therefore, it is convenient to make the dust trapping device 12 easy to attach to and detach from the chimney 9. Scattering of dust usually becomes a problem when long-term exhaust heat recovery boilers are in operation, such as acid ammonium sulfate, ammonium sulfate, and ash dust that adheres to the internal wall of the boiler, etc. In order to prevent this, the function may be exhibited when the operation of the exhaust heat recovery boiler 2 is resumed.

  2 shows a plan view of the entire wire net type dust trap 12 arranged in the chimney 9, and FIG. 3 shows a partial side view thereof. 4 shows a layout of the support beam 14 and the beam support member 21 of the wire net type dust trap 12 that is mounted in advance in the chimney 9. FIG. 5 is a cross-sectional view taken along line AA in FIG. Shows a sectional view taken along line BB or CC in FIG. 7 shows a side view of a wire mesh frame 12d arranged on the support beam 14 of the wire mesh dust trapping device 12 shown in FIG. 4, and FIG. 8 is a plan view of various frames of the wire mesh frame (FIG. 8 ( a) to (d)).

A plurality of support beams 14 of the dust trapping device 12 shown in FIG. 5, which is a cross-sectional view taken along the line AA of FIG. 4, are arranged in parallel with each other on the horizontal surface of the chimney 9.
As shown in FIG. 2, the chimney 9 is composed of a refractory material 15 and a steel material 16 attached to the inside of the refractory material 15, and as shown in FIG. 3, the support beam 14 is a vertical having a plane in the vertical direction. A cross section composed of a portion 14a and a horizontal portion 14b welded to the lower end of the vertical portion 14a is T-shaped. Further, a seal plate 20 is connected to a ring-shaped horizontal piece 19 welded and connected in the circumferential direction of the steel material 16 on the inner wall of the chimney 9, for example, by welding, and the support beam 14 is placed on the seal plate 20. The horizontal portion 14b is placed.

  FIG. 9 shows an enlarged view in a circle indicated by an arrow D in FIG. The chimney 9 has a structure in which a steel material 16 is attached to the inside of the refractory material 15 and the refractory material 15, and a pair of steel insertion pieces 18, 18 provided on the steel material 16 and a vertical portion 14 a of a T-shaped support beam 14. The end of this is inserted and bolted to make it detachable.

Further, as shown in the sectional view taken along the line BB or CC in FIG. 4 in FIG. 6, the bottom surface of the horizontal portion 14 b of the T-shaped support beam 14 is orthogonal to the longitudinal direction of the T-shaped support beam 14. The four support beam support members 21 provided in are connected by bolts. As shown in FIG. 4, two of the four beam support members 21 are arranged on the same straight line.
The dust trapping device 12 placed on the T-shaped support beam 14 partially supported by the support beam support member 21 has a triple wire mesh 12a to 12c and bolts as shown in FIG. It consists of a frame body 12d and a fixing member 12e that are sandwiched and fixed.

Further, the frame body 12d of the dust trapping device 12 is divided into a size that can hold a single mass and has a frame body of the largest size placed on the center of the chimney 9 12d ₁ ( consists to FIG. 8 (a)) that has the frame of the smallest size from 12d ₄ (to FIG. 8 (d)) to four of the frame 12d ₁ to 12d ₄ size. Each of these dust traps 12 is placed on a T-shaped support beam 14 partially supported by a support beam support member 21 shown in FIG. However, there is a deformation space in which the dust trapping device 12 having a rectangular planar shape cannot be placed in the inner peripheral portion of the chimney 9, but the seal plate 20 is placed in that portion. In addition, since the horizontal piece 19 provided in the steel material 16 which comprises the inner wall of the chimney 9 is weld-connected to the part in which the dust trap 12 of the chimney 9 is mounted, this horizontal piece 19 and the horizontal part 14b of the support beam 14 are connected. The seal plate 20 can be welded to the top. After the dust trapping device 12 is placed, the dust trapping device 12 is bolted to the horizontal portion 14 b of the support beam 14.

  Normally, the dust trapping wire mesh 12 is removed from the chimney 9, and the support beam 14 and the support beam support member 21 are permanently installed. During the restart operation of the exhaust heat recovery boiler 2 after the periodic inspection, the damper 10 is fully closed and fixed, and the upper part thereof is used as a working scaffold. The dust trapping wire mesh 12 is suspended from the upper part or is carried from a manhole (not shown) provided above the damper 10 of the chimney 9 and fixed to the support beam 14 with bolts.

Since dust such as dust is scattered at the initial concentration when the exhaust heat recovery boiler 2 is restarted, the state of adhesion is monitored while the exhaust gas source is properly started and stopped. When adhesion of dust or the like increases and flow resistance increases, a sheet is stretched on the upper surface of the damper 10, and the dust trapping wire mesh 12 is cleaned from above by air blow or from the upper surface of the damper 10. If this is repeated several times, the scattering of soot and the like hardly occurs and the exhaust heat recovery boiler 2 can be operated without the soot trap 12.
In that case, the dust trapping wire mesh 12 may be removed again to avoid an increase in flow resistance during normal operation.

  Since the clearance between the damper 10 and the dust trapping wire mesh 12 is provided with a work floor in consideration of the approach to the damper 10 for attaching / detaching and cleaning the dust trapping wire mesh 12, it can be used. In consideration of workability, about 0.5 to 2.5 m is optimal.

  The present invention can be applied to a chimney portion of an apparatus that uses exhaust gas from a combustion apparatus that contains a sulfur content resulting from combustion products. Examples of the apparatus include an exhaust heat recovery boiler and a combustion apparatus that easily generates soot and the like. is there.

The whole structure of the chimney of the exhaust heat recovery boiler exit of a present Example is shown. The top view of the whole wire-mesh type | mold dust capture device arrange | positioned in the chimney of FIG. 1 is shown. The partial side view of the wire-mesh type dust trapping device of FIG. 2 is shown. FIG. 3 is a layout view of support beams of the wire net type dust trap of FIG. 2. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. The BB line or CC line sectional drawing of FIG. 4 is shown. The side view of the wire-mesh frame arrange | positioned on the support beam of the wire-mesh type dust trap shown in FIG. 4 is shown. The top view (FIG. 8 (a)-(d)) of the various frame bodies of the wire-mesh frame shown in FIG. 7 is shown. FIG. 5 is an enlarged view in a circle indicated by an arrow D in FIG. 4. The schematic of the apparatus structure of the conventional combined power plant is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Exhaust heat recovery boiler 3 Cargo saver 4 Evaporating pipe 5 Superheater 8 Main steam pipe 9 Chimney 10 Damper 11 Net-like damper 12 Wire mesh type dust trap 12a-c Wire net 12d Frame 12e Stopping member 14 Support beam 14a Support Beam vertical portion 14b Support beam horizontal portion 15 Refractory material 16 Steel material 18 Insert piece 19 Horizontal piece 20 Seal plate 21 Support beam support member

Claims (4)

In the vertical chimney for exhaust gas with a damper inside,
A chimney characterized in that a dust trap is installed on the support beam so that a plurality of wire mesh frames are detachably mounted on the upper part of the damper.   The wire netting type dust trapping device includes a vertical beam portion having a plane in the vertical direction and a horizontal beam portion having a plane in the horizontal direction at the lower end of the vertical beam portion. The chimney according to claim 1, further comprising a support beam having a letter shape and a detachable wire mesh frame placed on a horizontal beam portion of the support beam.   The chimney according to claim 1 or 2, wherein a metal net type dust trap device is provided 0.5m to 2.5m above the damper. In an exhaust heat recovery boiler in which a large number of heat transfer tube groups and a denitration device are arranged in a duct through which combustion exhaust gas from a gas turbine flows,
An exhaust heat recovery boiler using the chimney according to any one of claims 1 to 3 as a chimney for discharging the gas turbine combustion exhaust gas after heat exchange with the heat transfer tube group to the atmosphere.

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