JP2015175525A - Exhaust gas flow rectification structure, exhaust heat recovery boiler with this rectification structure and rectification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas rectification structure capable of reducing load of exhaust gas, an exhaust heat recovery boiler with this rectification structure and a rectification method.SOLUTION: This invention relates to an exhaust gas rectification structure in which exhaust gas from a gas turbine 1 is rectified by a rectifier 8 and guided to a group 7 of heat transfer pipes of an exhaust heat recovery boiler 2. The rectifier 8 has a smaller section than that of an exhaust gas flow passage 6 at its installation position and arranged at a position where at least maximum flow speed portion of the exhaust gas flowing at a section of the exhaust gas flow passage 6 at the arranged position is rectified. It is preferable that the rectifier 8 is arranged at a position where its center becomes the maximum flow speed portion of the exhaust gas.

Description

  The present invention relates to an exhaust gas rectification structure that guides combustion exhaust gas discharged from a gas turbine by rectifying the exhaust gas to an exhaust heat recovery boiler, an exhaust heat recovery boiler including the rectification structure, and a rectification method.

  Generally, a heat recovery steam generator (HRSG) guides high-temperature combustion exhaust gas (hereinafter referred to as exhaust gas) discharged from a gas turbine to a plurality of heat transfer tubes of the exhaust heat recovery boiler through a duct. The heat of exhaust gas is recovered. The exhaust heat recovery boiler generates high-temperature steam by the recovered heat and rotates the steam turbine.

  Here, the exhaust gas flowing inside the duct is that the exhaust gas led from the gas turbine is a swirl flow and is not a uniform flow, the introduction position of the exhaust gas led from the gas turbine to the duct, and the flow path cross-sectional area of the duct A drift occurs due to the influence of the shape of the duct, which becomes larger toward the downstream side.

  In the exhaust heat recovery boiler, if there is a drift in the exhaust gas to be guided, heat recovery in the plurality of heat transfer tubes becomes unstable, and as a result, the boiler performance becomes unstable. Here, if the length of the duct connecting the gas turbine and the exhaust heat recovery boiler is set to a sufficient length, the influence of drift can be suppressed. However, at present, there are many cases where the duct length cannot be secured to a sufficient length to suppress the influence of the drift due to constraints on the layout of the plant.

  Therefore, in the prior art described in Patent Document 1, the rectifying plate is arranged over the entire cross section of the flow path through which the exhaust gas flows, and the exhaust gas is rectified by the rectifying plate and led to the downstream exhaust heat recovery boiler.

Japanese Utility Model Publication No. 6-6901

  However, in recent years, the flow rate of exhaust gas has increased and the flow rate of exhaust gas has increased as the output of gas turbines has increased. If the rectifying plate is placed in the entire cross-section of the flow path through which the exhaust gas flows in such a situation, the load due to the exhaust gas becomes large, and a design that can withstand the large load is required. It was.

  Accordingly, an object of the present invention is to provide an exhaust gas rectifying structure capable of reducing a load caused by exhaust gas, an exhaust heat recovery boiler including the rectifying structure, and a rectifying method.

  The present invention provides an exhaust gas rectifying structure that rectifies exhaust gas from a gas turbine by a rectifier and guides the exhaust gas to a heat transfer tube group of an exhaust heat recovery boiler, wherein the rectifier is smaller than a size of a cross section of the exhaust gas in the arrangement position. In the exhaust gas flowing through the cross section of the exhaust gas at the arrangement position, the exhaust gas is arranged at a position where at least the maximum flow velocity portion is rectified.

  It is preferable that the rectifying body is disposed at a position such that the center thereof is the maximum flow velocity portion of the exhaust gas.

  The rectifier includes a plurality of rectifiers having different sizes, and the plurality of rectifiers are arranged along a flow direction of the exhaust gas, and are arranged so that a height and a width increase toward a downstream side. be able to.

  The rectifier includes a plurality of rectifiers of different sizes, and the plurality of rectifiers are arranged along the flow direction of the exhaust gas, and the maximum flow velocity of the exhaust gas when viewed along the flow direction of the exhaust gas It can arrange | position so that an overlapping part may decrease, so that it goes outside centering on a part.

  The exhaust heat recovery boiler preferably includes the exhaust gas rectifying structure.

  In the exhaust gas rectification method that rectifies the exhaust gas from the gas turbine by the rectifier and leads it to the heat transfer tube group of the exhaust heat recovery boiler, the exhaust gas is partially rectified by the rectifier and the remainder does not go through the rectifier. It is characterized by being flowed downstream.

  According to the exhaust gas rectifying structure, the exhaust heat recovery boiler including the rectifying structure, and the rectifying method of the present invention, the load due to the exhaust gas can be reduced.

(A) is a side view showing an embodiment 1 of the rectifying structure of the present invention. (B) is an IB-IB arrow line view of Drawing 1 (A). (A) is a side view showing a second embodiment of the rectifying structure of the present invention. (B) is the IIB-IIB arrow directional view of FIG. 2 (A).

  Hereinafter, an example of an embodiment for carrying out the present invention (hereinafter abbreviated as Example 1) will be described with reference to FIG. FIG. 1A is a side view showing a first embodiment of the rectifying structure of the present invention. FIG. 1B is a IB-IB arrow view of FIG. 1A, and is a front view showing a state where the rectifying structure of the first embodiment is viewed from the upstream side.

  The gas turbine 1 is rotated by combustion gas, and discharges high-temperature combustion exhaust gas (hereinafter abbreviated as exhaust gas) that is 500 ° C. or higher with respect to the axial direction. The gas turbine 1 is, for example, a high-power gas turbine in which the exhaust gas flow velocity exceeds 100 (m / s). The exhaust gas is a swirl flow having straightness, and the flow velocity is the fastest at the swivel center portion, and the flow velocity is slowed away from the swivel center.

  The duct 3 is a flow path that guides exhaust gas from the gas turbine 1 to the exhaust heat recovery boiler 2. The shape of the flow path is such that the cross-sectional area of the flow path increases from the gas turbine 1 toward the exhaust heat recovery boiler 2. In addition, the entrance of the duct 3 is formed at a position in the center in the width direction of the duct 3 and deviated downward from the center in the height direction. The inlet of the duct 3 is formed at a position such that the opening center passes through the axis of the gas turbine 1.

  The exhaust heat recovery boiler 2 includes a boiler casing 5. The boiler casing 5 has one end connected to the outlet of the duct 3 and the other end connected to a duct or chimney not shown. The boiler casing 5 forms an exhaust gas flow path 6 with the duct 3.

  In the boiler casing 5, a plurality of heat transfer tubes are suspended from the boiler casing 5 to constitute a heat transfer tube group 7. The heat transfer tube group 7 generates steam by exchanging heat with the high-temperature exhaust gas from the gas turbine 1 guided through the duct 3. The exhaust gas whose temperature has been reduced by heat exchange with the heat transfer tube group 7 is discharged from the chimney to the atmosphere.

  Next, the rectifier 8 will be described. The exhaust gas from the gas turbine 1 flowing through the duct 3 is not uniform when it is discharged from the gas turbine 1, and further drifted due to the influence of the duct shape. The rectifying body 8 is a rectangular plate that rectifies the exhaust gas in which such drift has occurred, and is, for example, a perforated plate in which a plurality of through holes are formed in the rectifying surface 8a. The rectifying surface 8a rectifies the exhaust gas in which the drift has occurred with a plurality of through holes.

  The rectifying body 8 is attached to the steel frame 10 and disposed inside the duct 3. The rectifying body 8 is smaller than the cross-sectional size of the exhaust gas flow path 6 at the arrangement position, and is arranged so that the rectifying surface 8 a covers a part of the flow path cross section of the duct 3.

  In Example 1, non-resistance regions in which the rectifier 8 is not disposed are formed in four regions on both sides in the width direction and in the upper and lower sides of the exhaust gas flow path 6. Without passing, it flows directly to the downstream heat transfer tube group 7.

  Here, a part of the cross section of the flow path of the duct 3 is, for example, a place where the maximum drag is generated in the virtual plate when the virtual plate covering the entire flow path is disposed at the position where the rectifier 8 is disposed. The center is the range that receives a drag of 10% or more of the maximum drag.

  The rectifier 8 is disposed at a position where at least the maximum flow velocity portion of the exhaust gas flowing through the cross section of the exhaust gas flow path 6 at the arrangement position is rectified. And it is preferable that this rectification | straightening body 8 is arrange | positioned so that the center may be located in the maximum flow velocity part of waste gas. Here, the maximum flow velocity portion of the exhaust gas is located on the axis of the gas turbine 1.

  According to the exhaust gas rectifying structure of the first embodiment, the rectifier 8 is smaller than the cross-sectional size of the exhaust gas flow path 6 at the arrangement position. The rectifying body 8 is disposed at a position for rectifying at least the maximum flow velocity portion of the exhaust gas flowing through the cross section of the exhaust gas flow path 6 at the arrangement position. Therefore, in the exhaust gas flowing through the cross section of the exhaust gas flow path 6 at the position where the rectifying body 8 is disposed, a part of the exhaust gas including the maximum flow velocity portion is rectified by the rectifying body 8, and the remaining exhaust gas is not passed through the rectifying body 8. Flowed downstream.

  Thereby, the exhaust gas rectifying structure of Example 1 can reduce the load due to the exhaust gas as compared with the configuration in which a perforated plate is arranged in the entire flow path cross section of the duct 3 of the prior art to rectify all the exhaust gas, The back pressure of the gas turbine 1 can be reduced.

  Further, according to the exhaust gas rectifying structure of the first embodiment, the rectifying body 8 is arranged at a position such that the center thereof is the maximum flow velocity portion of the exhaust gas. Here, the exhaust gas is a swirling flow whose flow velocity decreases as the distance from the maximum flow velocity portion increases. For this reason, the rectifier 8 can efficiently reduce the drift of the exhaust gas.

  Further, according to the exhaust heat recovery boiler 2 having the exhaust gas rectifying structure of the first embodiment, the exhaust gas is rectified by the exhaust gas rectifying structure having the rectifier 8, so that heat recovery in the heat transfer tube group 7 is stable. As a result, the boiler performance is stabilized.

  Further, according to the exhaust gas rectification method of the first embodiment, a part of the exhaust gas including the maximum flow velocity portion is rectified by the rectifier 8, and the remaining part flows downstream without the rectifier 8. Thereby, the exhaust gas rectification method of Example 1 can reduce the load due to the exhaust gas as compared with the configuration in which the perforated plate is arranged in the entire flow path cross-section of the duct 3 of the prior art to rectify all the exhaust gas, The back pressure of the gas turbine 1 can be reduced.

  Hereinafter, Example 2 (hereinafter abbreviated as Example 2) of an embodiment for carrying out the present invention will be described with reference to FIG. FIG. 2A is a side view showing Example 2 in the exhaust gas rectifying structure of the present invention. FIG. 2B is a front view of the rectifying structure of Example 2 as viewed from the upstream side, as viewed from the arrow IIB-IIB in FIG.

  The exhaust gas rectifying structure of Example 2 is the same as that of Example 1 because the basic configuration of the exhaust gas rectifying structure is the same as that of Example 1 except for the auxiliary rectifier 18. The description which overlaps with description of the said Example 1 is abbreviate | omitted.

  The exhaust gas rectifying structure according to the second embodiment includes a rectifying body 8 and an auxiliary rectifying body 18 smaller than the rectifying body 8. The rectifier 8 and the auxiliary rectifier 18 having different sizes are, for example, meshes that rectify the exhaust gas by generating resistance in the exhaust gas.

  The rectifier 8 and the auxiliary rectifier 18 are disposed on the downstream side of the auxiliary rectifier 18 along the flow direction of the exhaust gas, and when the rectifier 8 and the auxiliary rectifier 18 are viewed along the flow direction of the exhaust gas, The rectifying body 8 and the auxiliary rectifying body 18 overlap each other at a portion including the maximum flow velocity portion, and are arranged so as not to overlap at a position deviating from the center to the outside.

  In Example 2, for example, when a virtual plate that covers the entire flow path is disposed at a position where the rectifying body 8 is disposed, 70% or more of the maximum drag is centered on a location where the maximum drag is generated on the virtual plate. The rectifier 8 and the auxiliary rectifier 18 are arranged so as to overlap in the range where the drag is generated, and the range where the drag of 25% or more of the maximum drag and less than 70% of the maximum drag is generated is only the rectifier 8. It arranges so that it may rectify with.

  According to the exhaust gas rectifying structure of the second embodiment, the rectifier 8 and the auxiliary rectifier 18 are arranged along the flow direction of the exhaust gas, and the height and width increase toward the downstream.

  That is, in the exhaust gas rectifying structure of Example 2, the maximum flow velocity portion of the exhaust gas is rectified by the rectifier 8 and the auxiliary rectifier 18, and the portion where the flow velocity is slower than the maximum flow velocity portion is arranged on the downstream side. Just rectify. For this reason, compared with Example 1, exhaust gas can be efficiently rectified according to the flow rate of exhaust gas.

  The exhaust gas rectifying structure, the exhaust heat recovery boiler including the rectifying structure, and the rectifying method of the present invention are not limited to the above-described embodiments. For example, although the description has been given of the configuration in which the rectifying body 8 is disposed inside the duct 3, the present invention is not limited to this. The rectifier 8 may be anywhere as long as it is a flow path between the gas turbine 1 and the heat transfer tube group 7. For example, the rectifier 8 may be disposed in the boiler casing 5.

  Further, in the exhaust gas rectifying structure of the present invention, the exhaust heat recovery boiler and the rectifying method provided with the rectifying structure, the inlet of the duct 3 is located at the center in the width direction of the duct 3 and downward from the center in the height direction. Although it demonstrated in the structure formed in the position which deviated and the opening center of the inlet_port | entrance of the duct 3 passes along the axis line of the gas turbine 1, it is not limited to this. For example, the entrance of the duct 3 may be formed at a central position in the width direction and the height direction of the duct 3, may be off to the left or right in the width direction, or may be off on the height direction. Further, the opening center of the inlet of the duct 3 may be off the axis of the gas turbine 1.

  Further, in the exhaust gas rectifying structure of the present invention, the exhaust heat recovery boiler and the rectifying method provided with the rectifying structure, the rectifying bodies 8 are not disposed on both sides of the exhaust gas flow path 6 in the width direction and above and below in the height direction. Although the region has been described and the exhaust gas flows directly to the downstream heat transfer tube group 7 without passing through the rectifier 8 in that region, the present invention is not limited to this configuration. The region where the rectifying body 8 is not disposed may be such that at least one of the left and right ends in the width direction and the upper and lower portions in the height direction flow the exhaust gas downstream as it is.

  In the exhaust gas rectifying structure of the second embodiment, the rectifying body 8 and the auxiliary rectifying body 18 have been described. However, the present invention is not limited to this. For example, there are three or more rectifiers, and the three or more rectifiers are arranged such that a larger rectifier is arranged on the downstream side along the flow direction of the exhaust gas, and the exhaust gas when viewed along the flow direction of the exhaust gas. A configuration may be adopted in which the overlapping portion decreases toward the outside with the maximum flow velocity portion as the center.

  Moreover, about the rectifying body, although using the porous plate with the structure of Example 1 and using the mesh with the structure of Example 2 was illustrated, it is not limited to this. A mesh may be used in the configuration of Example 1, and a porous plate may be used in the configuration of Example 2.

  Further, in the exhaust gas rectifying structure of Example 2, the exhaust heat recovery boiler and the rectifying method provided with this rectifying structure, the rectifier 8 and the auxiliary rectifier 18 are both illustrated as meshes, but the present invention is not limited thereto. One may be a mesh and the other may be a perforated plate.

  Moreover, although the rectangle was illustrated about the shape of the rectifier, it is not limited to this, A circle etc. may be sufficient. In the exhaust gas rectification structure of Example 2, the exhaust heat recovery boiler and the rectification method provided with this rectification structure, when the shape of the rectifier is circular, the diameter increases toward the downstream.

Further, in the exhaust gas rectification structure of Example 2, the exhaust heat recovery boiler and the rectification method provided with the rectification structure, the plurality of rectifiers having different sizes are arranged along the flow direction of the exhaust gas, You may make it arrange | position so that an overlap part may reduce, so that it goes outside centering on the maximum flow velocity part of waste gas when it sees along a flow direction. That is, the arrangement is not limited to the arrangement in which the height and width increase toward the downstream side along the flow direction of the exhaust gas, and the arrangement may be such that the height and width decrease toward the downstream, and are not arranged in order of size. Also good. According to such an arrangement, a flexible rectifying body can be arranged in accordance with the flow path of the exhaust gas.

  The exhaust gas rectifying structure, the exhaust heat recovery boiler including the rectifying structure, and the rectifying method of the present invention can be variously modified without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Gas turbine 2 Exhaust heat recovery boiler 6 Exhaust gas flow path 7 Heat transfer tube group 8 Rectifier 18 Auxiliary rectifier

Claims (6)

In the exhaust gas rectification structure that rectifies the exhaust gas from the gas turbine by the rectifier and leads it to the heat transfer tube group of the exhaust heat recovery boiler,
The rectifying body is smaller than a size of a flow passage cross section of the exhaust gas at the arrangement position, and is arranged at a position for rectifying at least a maximum flow velocity portion of the exhaust gas flowing through the flow passage cross section of the exhaust gas at the arrangement position. Exhaust gas rectification structure.   The exhaust gas rectifying structure according to claim 1, wherein the rectifying body is disposed at a position such that a center thereof is a maximum flow velocity portion of the exhaust gas. The rectifier comprises a plurality of rectifiers of different sizes,
The exhaust gas rectifying structure according to claim 2, wherein the plurality of rectifying bodies are arranged along a flow direction of the exhaust gas, and are arranged so that a height and a width thereof increase toward a downstream side. . The rectifier comprises a plurality of rectifiers of different sizes,
The plurality of rectifiers are arranged along the flow direction of the exhaust gas, and arranged so that the overlapping portion decreases toward the outside centering on the maximum flow velocity portion of the exhaust gas when viewed along the flow direction of the exhaust gas. The exhaust gas rectifying structure according to claim 2, wherein   An exhaust heat recovery boiler comprising the exhaust gas rectifying structure according to any one of claims 1 to 4.   In the exhaust gas rectification method that rectifies the exhaust gas from the gas turbine by the rectifier and leads it to the heat transfer tube group of the exhaust heat recovery boiler, the exhaust gas is partially rectified by the rectifier and the remainder does not go through the rectifier. An exhaust gas rectification method, wherein the exhaust gas is caused to flow downstream.

Images