JP2001116201A - Waste heat recovery boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste heat recovery boiler having a heat transfer pipe support structure capable of selfsupportingly installing a heat transfer pipe having a height at which buckling heretofore occurs by improving the limit buckling height of a heat transfer pipe panel. SOLUTION: A heat transfer pipe panel 34 is bent in a V-shape, as seen from above, to a flow of exhaust gas 1 to form a heat transfer pipe group, and width is provided with regard the direction of an exhaust gas flow. Since, as mentioned above, wide width is provided with regard to the direction of an exhaust gas flow and heat transfer pipes 26 are respectively coupled together by supports 35, a section secondary moment against bending is increased and as a result, bending rigidity of a heat transfer pipe panel 34 is improved, whereby the limit bucking height by tare weight available when a self-standing support system is employed is further increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust heat recovery boiler, and more particularly to an exhaust heat recovery boiler characterized by a support structure of a heat transfer tube installed in the exhaust heat recovery boiler.

[0002]

2. Description of the Related Art A combined cycle power plant is
In addition to the power generation by the gas turbine, the heat in the exhaust gas discharged from the gas turbine is recovered by a waste heat recovery boiler to generate steam, and the steam turbine also generates power. In general, combined cycle power plants have high load responsiveness in addition to high power generation efficiency.
Since it can cope with a sudden increase in power demand, it has been used frequently in recent years.

FIG. 4 shows an example of the configuration of a conventional heat recovery steam generator. This exhaust heat recovery boiler is a horizontal type natural circulation boiler in which steam drums 11 and 12 are arranged on the upper part and heat transfer tubes are arranged in a vertical direction. In this boiler, a superheater 3, a high-pressure evaporator 4, a denitration device 5, a high-pressure economizer 6, a low-pressure evaporator 7, and a low-pressure economizer 8 are arranged along the gas flow direction in the casing 2.

In the exhaust heat recovery boiler having such a configuration, the exhaust gas 1 from the gas turbine flowing into the casing 2 is used.
After the heat is exchanged in the superheater 3 and the high-pressure evaporator 4, the gas enters the denitration apparatus 5, and nitrogen oxides contained in the exhaust gas 1 are removed. Further, the exhaust gas 1 sequentially passes through the high-pressure economizer 6, the low-pressure evaporator 7, and the low-pressure economizer 8, exchanges heat with the internal fluid in the heat transfer tube, and is discharged from a chimney (not shown) in a state where the temperature is lowered. Is done.

The superheater 3, high-pressure evaporator 4, high-pressure economizer 6, low-pressure evaporator 7, and low-pressure economizer 8 shown in FIG.
Each is composed of a group of heat transfer tubes arranged in the vertical direction. These vertically arranged heat transfer tube groups are supported by either a hanging type or a self-standing type.

FIG. 5 is a view showing a heat transfer tube group supported by a hanging type support method, here a support state of a heat transfer tube panel. In this example, four sets of heat transfer tube panels 34 configured by connecting the upper header 24 and the lower header 28 with a plurality of heat transfer tubes 26 are arranged, and each of the heat transfer tube panels 34 is supported by the suspending member 25. It is suspended from the beam 21. A lug 29 is attached to the lower header 28 via a header support member 27. The lug 29 is accommodated in a bracket 30, and the position of the lug 29 is regulated to transmit the exhaust gas 1 in the flow direction. The heat tube panel can be prevented from swaying.

A space is provided between the lug 29 and the bracket 30 in the vertical direction so that the heat transfer tube 26 can absorb the expansion due to the thermal expansion. Further, the heat transfer tubes 26 are connected to each other to suppress vibration caused by the steam flow. As this connection method, for example, a structure called a honeycomb support 35 as shown in FIG. 7 is employed. In FIG. 5, reference numerals 22 and 31 are heat insulating materials,
Reference numerals 23 and 32 denote casings, and reference numeral 33 denotes a support beam.

FIG. 6 is a view showing a heat transfer tube group (heat transfer tube panel) supported by a self-supporting supporting method. In this example, the upper header 24, the heat transfer tube 26, and the lower header 28
The four sets of heat transfer tube panels 34 are made independent. Also in the self-supporting system, the heat transfer tubes 26 are connected by a honeycomb support 35 or the like as in the case of the hanging system (FIG. 7). Note that, as in FIG.
Denotes a heat insulating material, and 32 denotes a support beam for the casing.

[0009]

By the way, in the above-mentioned suspension type support system, there is an advantage that buckling breakage does not occur in the heat transfer tubes 26, but the entire weight of the heat transfer tube panel group is suspended by the support member 21. Since the support member 21 is lowered and supported, it is necessary to use a large member having high rigidity for the support member 21 and a steel frame supporting the support member 21 from the foundation, which inevitably increases the cost. On the other hand, in the self-supporting system, the heat transfer tubes 2
6 is supported on the foundation via the support beam 33,
A beam for supporting the heat transfer tube 26 is not required in the upper casing. Therefore, it is advantageous in terms of cost as compared with the hanging type, and it is preferable to adopt a self-supporting type rather than the hanging type as a method of supporting the heat transfer tube.

[0010] However, in the self-supporting support system, as shown in FIG. 9, the heat transfer tube panel 34 may cause buckling failure due to its own weight, and the height of the heat transfer tube is naturally limited. That is, when the size of the boiler is increased and the height of the heat transfer tube is increased, buckling breakage due to its own weight becomes a problem particularly in a region where the gas temperature on the upstream side of the exhaust gas is high. Therefore, a self-supporting support system cannot be adopted this time.

FIG. 8 is a characteristic diagram showing the relationship between the heat transfer tube height and the buckling limit load determined by FEM analysis. As can be seen from FIG. 8, as the height of the heat transfer tube increases, the load due to its own weight increases. When the height exceeds a certain height, the load exceeds the limit buckling load, and a structure alone cannot be constructed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the limit buckling height of a heat transfer tube panel, and to make a high heat transfer tube that is buckled in the past stand alone. It is an object of the present invention to provide a heat recovery steam generator provided with a heat transfer tube supporting structure capable of performing the heat recovery.

[0013]

To achieve the above object, the present invention relates to a waste heat recovery boiler which performs heat exchange by independently arranging a plurality of heat transfer tube groups in a direction transverse to a gas flow direction. The heat transfer tube group is provided with a portion that has advanced to the flow direction of the exhaust gas and a portion that retreats, and each heat transfer tube is connected by a connecting member, and has a width in a direction parallel to the flow direction to be independent. It was configured as follows.

[0014] In this case, even if the heat transfer tubes are arranged upright on the lower header having a portion bent in a U shape when viewed in plan, the heat transfer tubes are arranged in a predetermined number of straight lines in plan view. Thus, one unit of the heat transfer tube group may be configured, and the heat transfer tube groups of the adjacent units may be connected with a relative angle.

In the present embodiment, a honeycomb support is used as a connecting member.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In the following description,
The same parts as those in the conventional example described above are denoted by the same reference numerals,
Duplicate description will be omitted.

In the present invention, as shown in the conceptual diagram of FIG. 2, the heat transfer tube group is arranged in a V-shape (FIG. 2A) when viewed from above (in plan view) with respect to the flow direction of the exhaust gas 1, It has a width in the exhaust gas flow direction (FIG. 2B). If the width can be made large in the exhaust gas flow direction in this way, the heat transfer tubes 26 are connected by the supports 35, so that the second moment of area with respect to bending becomes large, and as a result, the bending of the heat transfer tube panel 34 The rigidity is improved. This makes it possible to further increase the limit buckling height due to its own weight when the self-supporting support method is adopted.

FIG. 1 is a view showing a structure of a heat transfer tube of the heat recovery steam generator according to the present embodiment. The heat transfer tubes 26 of the exhaust heat recovery boiler according to the present embodiment include the same components as those of the above-described conventional example shown in FIG. 6, namely, a heat transfer tube panel 34, a lower header 28, an upper header 24, and a honeycomb support 35. The following examples are composed of similar components. However, in order to improve the bending rigidity of the heat transfer tube panel 34, the lower header 28 is provided with a bent portion 36 substantially at the center (intermediate portion).
It is formed in a substantially “C” shape in plan view. The heat transfer tubes 26 are erected along the shape of the lower header 28, and are arranged in a substantially “<” shape having the same shape as the lower header 28 as a heat transfer tube group. In the case of this example, as shown in FIG.
The two heat transfer tubes 26 are provided in three rows, and are bent at a portion corresponding to the sixth heat transfer tube 26, so that the heat transfer tubes 26 have an overall shape of "". Each of the heat transfer tubes 26 is fastened by the honeycomb support 35 in the same manner as in the above-described conventional example (FIG. 1C), the relative positions of the heat transfer tubes 26 are determined, and as shown in FIG. (Direction perpendicular to the flow direction of exhaust gas 1)
Are arranged side by side. The three heat transfer tube panels 34 arranged in this manner are arranged in a plurality of stages in the furnace length direction (a direction parallel to the flow direction of the exhaust gas 1) to perform heat exchange. Other parts not particularly described are configured in the same manner as the above-described conventional example.

According to the FEM analysis, in the heat transfer tube group configured as described above, even when the heat transfer tube height was 20 m, which was difficult with the conventional structure, buckling failure due to its own weight did not occur.

In the embodiment shown in FIG.
8 itself is bent in the shape of a square, and the heat transfer tube 26
Although the group has an upright form, instead of bending the lower header 28 as shown in FIG. 3A instead of such a form, a set unit of heat transfer tube group is supported. The lower header 28 is arranged so as to be inclined with respect to the flow direction of the exhaust gas 1, and the adjacent heat transfer tube panels 34 are connected to each other and arranged at a predetermined angle from a direction orthogonal to the flow direction of the exhaust gas. You can also. FIG.
As shown in (b), some of the heat transfer tube panels 34 may be arranged so as to be orthogonal to the flow direction of the exhaust gas 1. Also in this case, the adjacent heat transfer tube panel 34 is arranged at an angle.

The adjacent heat transfer tube panels 34 are connected by a plate-like support 37. As the plate-like support 37, a metal plate provided with a hole through which the heat transfer tube 26 passes is fitted to each of the panels 34, and the panels are joined to each other by welding. With this configuration, since the lower header 28 does not have the bent portion 36 as compared with the embodiment shown in FIG. 1, it is easier to manufacture than the embodiment.

[0022]

As described above, according to the present invention, each of the heat transfer tube groups is provided with a portion that advances in the flow direction of the exhaust gas and a portion that retreats, and the heat transfer tubes are relatively fixed by the connecting member. Since the heat transfer tube panel is self-supported with a width in a direction parallel to the flow direction, the heat transfer tube panel can be of a self-supporting type even in an exhaust heat recovery boiler having a high heat transfer tube height. Thereby, the cost of the exhaust heat recovery boiler can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a structure of a heat transfer tube of an exhaust heat recovery boiler according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram for explaining a technical idea of the present invention.

FIG. 3 is a view showing an arrangement of a heat transfer tube panel of an exhaust heat recovery boiler according to another embodiment of the present invention.

FIG. 4 is a diagram showing a device configuration of a conventional heat recovery steam generator.

FIG. 5 is a diagram showing a structure of a conventional heat-transfer tube panel of a hanging type viewed from a direction orthogonal to a flow direction of exhaust gas.

FIG. 6 is a view of a conventional structure of a self-supporting heat transfer tube panel viewed from a direction orthogonal to a flow direction of exhaust gas.

FIG. 7 is a view showing a structure of a honeycomb support conventionally implemented.

FIG. 8 is a characteristic diagram showing a relationship between a ratio of a load applied to a heat transfer tube due to a limit buckling load and its own weight, and a height of the heat transfer tube.

FIG. 9 is a side view showing buckling deformation of the self-supporting heat transfer tube panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas 24 Upper header 26 Heat transfer tube 28 Lower header 33 Support beam 34 Heat transfer tube panel 35 Honeycomb support 36 Header bent part 37 Plate support

Claims (3)

[Claims] 1. An exhaust heat recovery boiler for independently exchanging heat by arranging a plurality of heat transfer tube groups in a direction transverse to a gas flow direction, wherein each of the heat transfer tube groups has advanced in the flow direction of exhaust gas. An exhaust heat recovery boiler, comprising: a portion and a retreated portion, wherein each heat transfer tube is connected by a connecting member, and has a width in a direction parallel to a flow direction to be self-standing. 2. The exhaust heat recovery boiler according to claim 1, wherein said heat transfer tube is erected on a lower header having a portion bent in a U shape in plan view. 3. A predetermined number of the heat transfer tubes are linearly arranged in a plan view to constitute one unit of heat transfer tube group, and adjacent heat transfer tube groups of each unit are connected with a relative angle. The exhaust heat recovery boiler according to claim 1, wherein: