JP2585488B2 - Waste heat recovery boiler - Google Patents

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 having improved earthquake resistance.

[0002]

2. Description of the Related Art In general, a combined cycle power plant uses an exhaust heat recovery boiler that uses exhaust gas from a gas turbine or the like as a heat source for generating driving steam for a steam turbine or steam hot water for a process. .

FIG. 7 is a diagram showing an example of a general exhaust heat recovery boiler, which is a horizontal natural boiler in which a steam drum is disposed above equipment and heat transfer tubes are installed vertically. .

The exhaust heat recovery boiler 1 includes 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, which are sequentially arranged in a boiler duct 2. The exhaust gas flowing from the gas turbine or the like into the exhaust heat recovery boiler 1 passes through a superheater 3 and a high-pressure evaporator 4 to reach a denitration device 5 where nitrogen oxides contained therein are removed. The exhaust gas that has exited the denitration device 5 sequentially passes through the high-pressure economizer 6, the low-pressure evaporator 7, and the low-pressure economizer 8, and exchanges heat with the internal fluid in each heat transfer tube. The high-pressure steam drum 9 and the low-pressure steam drum 1
At 0, the two-phase flow generated in the evaporator at each pressure flows in,
Separated into steam and boiler water.

[0005] Such a natural circulation type waste heat recovery boiler is
Compared to a forced circulation type waste heat recovery boiler, in addition to the advantage that a circulation pump is unnecessary and power in the plant can be reduced, the height from the ground to the top of the boiler can be kept low, and the boiler has a self-standing structure. And has advantages such as elimination of a support steel frame, and thus tends to be adopted in many combined cycle power plants.

FIG. 8 is a side view of an evaporator portion of the natural circulation type exhaust heat recovery boiler, and headers 12 and 13 are attached to upper and lower ends of a large number of evaporating tubes 11 arranged vertically. As a whole, one heat transfer panel is formed, and a plurality of heat transfer panels are disposed in the boiler duct 2 in the gas flow direction. The upper header 12 of the header is connected to a steam drum 15 via a riser 14, while the lower header 13 is connected to a manifold 17 via a water supply pipe 16. This manifold 17 is connected to the lower end of a downcomer 18 that extends downward from the steam drum 15, and is connected to the gas flow direction, that is, the steam drum 15.
Are oriented in a direction perpendicular to the axis of The weight of the steam drum 15 is supported and transmitted from the boiler duct casing to the foundation via a downcomer support member 19 attached to the lower end of the downcomer 18.

FIG. 9 is a front sectional view of the evaporator portion of the exhaust heat recovery boiler. In order to support the pressure of the exhaust gas flowing through the inside of the boiler duct 2, the boiler duct 2 is large at regular intervals in the axial direction of the boiler. A backstay 20 made of a beam material is provided. This backstay 20 is a boiler duct 2
The entire circumference of the boiler duct 2 is formed in a rectangular shape to support an out-of-plane load acting on the casing plate of the duct, and is lined with a heat insulating material to reduce the temperature to near the atmospheric temperature. The surface is welded and fixed.

Since a heavy heat transfer tube group is disposed in the boiler duct 2, when a horizontal force such as an earthquake force acts on the heat transfer tube group, the shear rigidity of the frame formed by the backstay 20 is increased. Will compete. When the strength is insufficient, the brace 21 is reinforced by attaching a brace 21 at a position corresponding to the backstay 20 in the boiler duct 2 as shown in FIG.

[0009]

However, in such an exhaust heat recovery boiler, when a horizontal force in the axial direction acts on the steam drum 15, the support member 19 of the downcomer 18.
Is weak, the axial displacement of the steam drum 15 occurs, the downcomer 18 bends around the axis of the manifold 17, cracks occur in various parts of the boiler, and the casing plate of the duct 2 An accident such as deformation may occur.

For this reason, conventionally, a means such as attaching a downcomer stopper 22 to the ceiling plate of the duct 2 has been provided. However, since the seismic force is transmitted to the ceiling plate as a tension / compression force, the compression side is not used. The ceiling plate, which is a thin plate having a thickness of several mm, has a problem that it is easily buckled and is not effectively transmitted to a highly rigid backstay or a brace surface.

[0011] In addition, in the currently planned large heat recovery steam generator, the weight of the steam drum is as large as 200 tons and the moment arm corresponding to the vertical length of the downcomer is considerably long. It is impossible to counter the horizontal force by increasing the bending rigidity of the lower part.
Moreover, both the steam drum and the downcomer are pressure-resistant members that receive a large internal pressure, and it is not desirable that such members share a large seismic force.

Further, in the conventional exhaust heat recovery boiler having the above-described steam drum support structure, the boiler duct 2 having relatively high rigidity and high natural frequency is provided by the provision of the backstay 20 and the brace 21. , Downcomer 18
And the steam drum 15 forming an inverted pendulum type vibration system which is supported by the lower part of the oscillating body and has low rigidity and generates low-frequency vibration. In particular, the arrangement of the tube groups having different depths in the gas flow direction causes a shift between the rigidity and the center of gravity, which may cause torsion vibration of the boiler duct.

In view of the foregoing, the present invention is to connect a steam drum to a rigid backstay and to greatly increase the seismic strength by setting the supporting structure of the steam drum to have high rigidity against horizontal movement. It is an object of the present invention to obtain an exhaust heat recovery boiler capable of performing heat recovery.

[0014]

SUMMARY OF THE INVENTION The present invention relates to an exhaust heat recovery boiler in which the own weight of a steam drum is supported by a downcomer attached to the steam drum. A stopper is protruded, and a steady rest at the center of the steam drum is connected to a backstay disposed on the outer periphery of the boiler duct so as to be slidable in the vertical direction and restrain the movement in the horizontal direction. The stopper is slidably connected to the backstay only in the vertical direction and the longitudinal direction of the steam drum.

[0015]

[Function] The horizontal force applied to the steam drum of the exhaust heat recovery boiler during an earthquake or the like is transmitted directly from the steam drum to the backstay, and is supported and transmitted by the rigidity of the backstay surface or the brace provided in the backstay surface. . Therefore, the steam drum and the boiler duct form an integrated vibrating body to form a stable vibration system having a high natural frequency, so that the rigidity of the entire boiler can be increased and the earthquake resistance can be improved.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a side view showing an evaporator portion of a natural circulation type exhaust heat recovery boiler according to the present invention. The boiler evaporator system is the same as that shown in FIG. That is, reference numeral 11
Denotes a plurality of evaporating tubes arranged in the direction of gravity.
The headers 12 and 13 are attached to the upper and lower ends of 1 respectively, and one heat transfer panel is constituted as a whole,
A plurality of heat transfer panels are arranged in the gas flow direction. The header 12 is connected to a steam drum 15 via a riser 14, while the lower header 13 is connected to a manifold 17 via a water supply 16. The manifold 17 has a downcomer 1 having one end connected to the steam drum 15.
8 at the other end, all of which form a circulation path for the evaporator. The weight of the steam drum 15 is reduced by the downcomer support member 19 attached to the lower end of the downcomer 18.
, And is supported by a boiler support member such as the lower back stay 20 via the lower side.

The steam drum 15 is disposed at an intermediate position between the adjacent back stays 20 disposed on the outer periphery of the boiler duct 2. It is protruding.
On the other hand, a horizontal force transmitting member 24 extending in the radial direction of the steam drum 15 is disposed at a position corresponding to the steam drum 15 between the adjacent back stays 20, and both ends thereof are connected to the back stay 20. A tubular member 25 is fixed to the horizontal force transmitting member 24 at a position corresponding to the steady rest 23 of the steam drum 15 (FIG. 2), and the tubular member 25 is fixed to the tubular member 25. A metal fitting 23 is slidably inserted up and down.

However, in the event of an earthquake or the like, the steam drum 1
The horizontal force acting in the direction of the axis 5 is transmitted from the steady rest 23 attached to the bottom surface of the central portion to the horizontal force transmitting member 24 via the cylindrical member 25, and exists on two sides with the steam drum 15 interposed therebetween. It is transmitted to the backstay 20. Then, the horizontal force once transmitted to the backstay 20 is transmitted to the bottom of the casing by the rigidity of the backstay surface or the rigidity of the brace, and finally transmitted to the ground. Further, the upward displacement of the steam drum due to the thermal expansion of the downcomer during the boiler operation is absorbed by the sliding movement of the steady rest 23 and the cylindrical member 25, and there is no possibility that thermal stress is generated in this portion. Also, thermal expansion in the longitudinal direction of the steam drum is not restrained at all.

As described above, according to the present embodiment, since the horizontal force acting on the steam drum 15 is not directly transmitted to the ceiling plate of the duct, there is no possibility that the ceiling plate will be buckled and deformed. Members such as the stopper 22 are not required. Furthermore, by eliminating the downcomer stopper 22, the moment due to the horizontal force applied from the ceiling plate penetration of the downcomer 18 to the steam drum 15 can be reduced to substantially zero, and the downcomer 18 serving as a pressure-resistant portion is provided. Alternatively, the influence of the bending moment on the body of the steam drum 15 can be reduced. Similarly, there is no need to share the horizontal force of the drum at the lower part of the downcomer, and the pressure-resistant portion can be made to have a safe and highly reliable structure.

As described above, the rigidity of the boiler duct 2 in the longitudinal direction of the steam drum is mainly constituted by the backstay 20 or the brace, and the horizontal force acting on the steam drum 15 via these main members is reduced. Will be processed
The support structure of the steam drum has a high rigidity and a high natural frequency with respect to the movement in the horizontal direction, and the earthquake resistance is improved.
Further, since the steam drum 15 and the duct form an integral vibrator, the vibration of the steam drum alone does not appear, a stable vibration system is obtained, rigidity can be easily secured, and earthquake resistance can be high.

The anti-sway fittings 23 are provided not only at the bottom of the central portion of the steam drum 15 but also at the bottom of both ends of the steam drum 15 in the longitudinal direction. On the other hand, the cylindrical members 25a, 25 into which the steady rests 23 at both ends are inserted and engaged.
The shape of the penetrating portion 5a is a long hole having a long diameter in the longitudinal direction of the steam drum so that the thermal expansion of the steam drum 15 in the longitudinal direction during operation is allowed.

Therefore, since the displacement of the steam drum 15 at both ends with respect to the boiler duct 2 is further restricted in the front-rear direction, the moment acting on the steam drum 15 around the vertical axis can be countered. That is, the horizontal force in the front-rear direction held at the end of the steam drum 15 is directly transmitted to the boiler foundation via the backstay 20.

However, even when the rigidity and the center of gravity of the boiler duct are deviated and torsional vibration occurs, the boiler duct 2 and the steam drum 15 are integrated in the front, rear, left and right directions, and the torsional vibration mode is eliminated. . This positively utilizes the large weight of the steam drum 15, and the boiler duct 2 in which torsional vibration is likely to occur.
Can be integrated with a very heavy and vibrationally unstable steam drum to provide a vibration system having a first moment of only simple back and forth movement.

FIG. 4 is a view showing another embodiment particularly for a large-sized waste heat recovery boiler. In a large-sized waste heat recovery boiler, both the outer diameter and the weight of the steam drum become very large. There are two protruding anti-sway fittings 26 at both the center and both ends.

On the other hand, the central horizontal force transmitting member 27 is constituted by two H-shaped steels 27a and 27b parallel to each other and an H-shaped steel 27c connecting the central portions of the two H-shaped steels 27a and 27b. The metal fitting 26 is composed of both H-shaped steels 27a, 27
The H-shaped steel 27c is inserted and engaged so as to sandwich the H-shaped steel 27c in the gap formed by b (FIGS. 4 and 5).

At both ends of the steam drum 15, box-shaped horizontal force receiving members 28 project from the front and rear back stays 20, 20. 26 are arranged to abut against each other (FIG. 6).

Thus, the longitudinal displacement of the steam drum 15 with respect to the boiler duct 2 is restrained by the H-shaped steels 27a and 27b, and the longitudinal displacement of the steam drum is controlled by the anti-vibration fittings 26 and the horizontal force receiving fittings 28 at both ends. Be bound.

[0029]

According to the present invention, as described above, the steam drum is connected to the backstay arranged on the outer periphery of the duct so as to restrict only the movement in the horizontal direction. It can be formed so as to form an integrated vibrator, and its supporting structure can have high rigidity and high natural frequency. Therefore, compared to the conventional apparatus, it can be made extremely high in earthquake resistance, and in particular, the horizontal load acting on a super heavy object such as a steam drum is processed by the structural member of the boiler duct,
There is no need for an extra support structure, and it is possible to achieve effects such as saving space and cost.

[Brief description of the drawings]

FIG. 1 is a side view of an evaporator portion of an exhaust heat recovery boiler according to the present invention.

FIG. 2 is a perspective view of a horizontal force transmitting member in FIG. 1;

FIG. 3 is a plan view of a second embodiment of the present invention.

FIG. 4 is a plan view of a third embodiment of the present invention.

FIG. 5 is a side view of a central portion in a third embodiment of the present invention.

FIG. 6 is a side view of an end according to a third embodiment of the present invention.

FIG. 7 is an explanatory diagram of the entire configuration of a general exhaust heat recovery boiler.

FIG. 8 is a side view of an evaporator section of a conventional exhaust heat recovery boiler.

FIG. 9 is a front view of an evaporator section of a conventional exhaust heat recovery boiler.

FIG. 10 is a front view of a brace portion for reinforcing a boiler duct of a conventional heat recovery steam generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Evaporation pipe 12 Upper header 13 Lower header 15 Steam drum 17 Manifold 18 Downcomer 19 Support member 20 Backstay 23, 26 Anti-sway fitting 24, 27 Horizontal force transmission member 25 Cylindrical member 28 Horizontal force receiving member

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshihiro Fujiwara 3-2-16-1 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. Toyosu General Office (56) References JP-A-62-266301 (JP) , A) Actually open sho 59-195304 (JP, U)

Claims (1)

(57) [Claims] 1. A steam drum is disposed above a boiler duct, and steam is generated by circulating can water from the steam drum to a heat transfer tube in the boiler duct, and the weight of the steam drum is reduced to the lower end of the downcomer. In an exhaust heat recovery boiler that is supported via an attached downcomer support member,
A steady rest is protruded at the center of the steam drum and on both sides in the longitudinal direction, and the steady rest at the center of the steam drum is slidable in a vertical direction with respect to a backstay arranged on the outer periphery of the boiler duct, and is slidable in a horizontal direction. The exhaust heat recovery boiler is characterized in that it is connected so as to restrict the movement of the steam generator, and the steady rests on both sides are slidably connected to the backstay only in the vertical direction and the longitudinal direction of the steam drum.