JP3181369B2 - Boiler damping support structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration control structure for a boiler, and more particularly to a vibration control structure for a boiler capable of reducing a response load during an earthquake.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional boiler apparatus supporting structure. In the figure, a boiler body 2 is suspended from a supporting steel frame 1 by a suspension rod 3 so as not to restrain thermal expansion during operation. Therefore, when an earthquake occurs, the boiler body 2 tends to swing like a hanging bell, but the seismic tie 4 is used to limit the relative displacement between the supporting steel frame 1 and the boiler body 2 that occurs at that time. Is provided. The limit of the relative displacement between the supporting steel frame 1 and the boiler main body 2 is set from the viewpoint of protection of pipes and ducts connected to the boiler main body 2.

[0003] The boiler main body 2 is roughly divided into a furnace part 2a and a cage part 2b. The furnace part 2a is a hollow box-shaped structure composed of a water wall formed by welding and connecting a heat transfer pipe between the heat transfer pipes through which boiler water passes by a plate material, whereas the cage part 2b has the above-described structure. A heat transfer tube group for performing convection heat transfer is installed in a box-shaped structure. Therefore, there is a great difference in the mass per unit volume (mass density).
The mass density of a is small, and the mass density of the cage part 2b is large. The mass ratio between the furnace part and the cage part is 1: 2, the volume ratio is 2: 1, and the mass density ratio is 1: 3. When comparing the front and rear or right and left sides of the boiler device,
In many cases, the mass distribution and rigidity distribution of the supporting steel frame 1 including the load are different.

[0004] As described above, the boiler apparatus usually has an asymmetric rigidity distribution or mass distribution in the front and rear, right and left directions of the supporting steel frame 1 and the boiler main body 2. The front, rear, left and right parts of the boiler device tend to vibrate at a natural period according to the rigidity and mass of each unit. Brace rigidity. Talking about the oscillation cycle,
The natural period T of the most basic degree of freedom system is: T = 2π√ (m / k), where m is mass and k is rigidity (spring constant). The spring constant k is obtained from the displacement δ generated when a force of F is applied to the mass point of the steel frame.

K = F / δ However, in the boiler supporting steel frame 1, the boiler body 2
It is inevitable to have a stairwell (hollow) structure to accommodate Since the boiler body is stored in the atrium,
A horizontal brace cannot be provided in the atrium. Therefore, the horizontal brace can be arranged only in the periphery of the atrium, and therefore, it is difficult to secure the rigidity (floor rigidity) of the horizontal brace so that each part of the supporting steel frame 1 is completely in phase. .

In such a structure having an asymmetric mass and rigidity distribution and not securing sufficient floor rigidity, the influence of a higher-order vibration mode higher than the second-order vibration mode occurs when an earthquake occurs. Cheap. Since it is inevitable that the moment when the influence of the higher-order vibration mode acts in a direction in which it is added to the first-order vibration mode, the influence of the higher-order vibration mode appears in a form that increases the seismic response. A boiler device in which higher-order vibration modes are likely to occur has a first-order natural period of the same level,
Moreover, compared to other structures having a uniform mass and rigidity, a large seismic response is generated.

[0007]

In the above prior art, no consideration is given to the structure of the boiler device in order to reduce the influence of the higher-order vibration mode, and the amount of seismic response due to the influence of the higher-order vibration mode is not considered. There is a problem that the increase is easily caused. An object of the present invention is to provide a boiler vibration control support structure that reduces the effects of higher-order vibration modes in a boiler device and reduces the response load when an earthquake occurs.

[0008]

Means for Solving the Problems To achieve the above object, a first invention of the present application is a support steel frame for supporting a boiler body, and a boiler suspended from the support steel frame so as to allow expansion and contraction due to heat. Seismic damping support for a boiler provided with a suspending member for suspending and supporting, and a seismic tie provided between the suspended boiler body and the supporting steel frame to limit the relative displacement between the suspended boiler and the supporting steel frame within the limit in structure, the furnace portion and the cage portion of the boiler body,該火furnace section
And relative displacement due to heat between cage and cage
Produces weak or no resistance,
Great resistance to sudden relative displacement during an earthquake
Characterized by being connected by a connecting device configured to generate
The boiler's seismic control structure.

A second aspect of the present invention, a supporting steel for supporting the boiler body, a member hanging down supporting hanging to the boiler body is suspended to the supporting steel frame to permit expansion and contraction due to heat, hung boiler in seismic damping support structure of the boiler provided with a seismic tie to limit supporting the relative displacement of both the event of an earthquake within the limits provided between the main body and the supporting steel frame, cage portion of the boiler body (or furnace Part)
Is provided as a base, and a connecting device that forms two sides of a triangle by connecting both ends of the base to a vertex provided in a furnace part (or a cage part) of the boiler body is provided.
Slow relative displacement due to heat between the part and the cage part
Generate weak resistance or generate resistance
Large resistance to sudden relative displacement during an earthquake
The present invention relates to a vibration control structure for a boiler, which is configured to generate a force .

[0010] The third invention is the first invention or the second invention.
The present invention relates to a vibration damping support structure for a boiler, wherein the connecting device is a damping mechanism type connecting device that absorbs seismic energy.

[0011]

The connecting device for connecting the furnace part and the cage part of the boiler main body generates resistance when a phase difference of the vibration of the furnace part and the cage part of the boiler main body is generated. Parts to each other. Also in the case where a phase difference occurs between the front and the back or the left and right of the supporting steel frame, each other is restrained through the boiler main body in the same manner as described above.

As described above, the coupling device generates a restraining force against the phase difference at the time of the occurrence of the earthquake, whereby the behavior of the entire boiler device approaches that of an integral unit, and the influence of higher-order vibration modes is reduced. .

[0013]

FIG. 1 shows an embodiment of a boiler vibration control structure according to the present invention.
Shown in The feature of the present invention resides in that the furnace part 2a and the cage part 2b of the boiler main body 2 are connected by the connecting device 5. In particular, as shown in FIG. 2, when the connecting device 5 is arranged so as to form two sides of a triangle, the connecting device 5 is effective against vibration of the boiler device in both front and rear, right and left directions.

The connecting device 5 has a characteristic that it hardly generates resistance to a very slow movement due to thermal expansion, and generates a sufficient resistance to a sudden movement when an earthquake occurs. It is necessary. An oil snubber has such characteristics. The oil snubber is as shown in FIG. 3, and when the piston 6 operates,
Oil is taken in and out of the reserve tank 8 via the valve 7. When the valve 7 is at rest, the flow path is opened by the spring 9, and the piston moves very slowly, that is, when the thermal expansion of the boiler body is absorbed, the oil flows out from the open flow path. As the piston speed increases, the pressure in the cylinder increases, and when the pressure overcomes the force of the spring 9, the valve 7 closes. As a result, it is possible to restrain rapid movement during an earthquake while absorbing thermal expansion.
FIG. 4 shows the characteristics of the oil snubber. As shown in FIG. 4A, the oil snubber has a low resistance when the piston speed v is low (thermal expansion), but has a high resistance when the piston speed is high (earthquake). When this is repeated with a simple vibration close to the vibration of the boiler device at the time of the occurrence of the earthquake, a behavior is obtained in which the spring has a slight damping effect as shown in FIG.

When a relative displacement occurs between the furnace part 2a and the cage part 2b of the boiler body 2 due to the phase difference of the vibration during the earthquake,
A resistance force substantially proportional to the relative displacement is generated in the oil snubber as the connection device 5. The resistance restrains the relative displacement from expanding. Therefore, the relative displacement between the furnace part 2a and the cage part 2b at the time of the earthquake becomes smaller as compared with the conventional structure without the coupling device. Therefore, at the time of an earthquake, the boiler device approaches the integrated vibration, and the influence of the higher-order mode is reduced.

The effect of reducing the influence of the higher-order mode differs depending on the boiler apparatus, and cannot be specified unconditionally. FIG. 5 shows the result of a trial calculation using a typical boiler apparatus. FIG. 5 shows the distribution of the bending moment generated in the boiler body by comparing the prior art with the present embodiment. As shown in FIG.
Compared with the prior art, in the embodiment of the present invention, the maximum bending moment generated at the upper part of the furnace part when the furnace part and the cage part swing closer to and away from each other due to the earthquake is reduced to about 3/4. The effect of the reduction of the maximum bending moment includes a resource saving effect accompanying a reduction in the weight of the reinforcing member of the boiler main body and an effect of improving the reliability of the boiler strength.

As another embodiment of the present invention, there is a boiler vibration control structure using a damping mechanism in the connecting device 5 of FIG. As a damping mechanism, there is a speed proportional type oil damper whose characteristics are shown in FIG. As shown in FIG. 6A, a resistance force is generated in proportion to the piston speed of the oil damper.
(B) shows a loop close to a circle. FIG.
The area surrounded by the loop in (b) corresponds to the amount of seismic energy absorbed. Therefore, when a speed proportional type oil damper is used for the coupling device, a vibration damping effect is generated by absorbing seismic energy in addition to generating a resistance force. As a speed proportional oil damper, an orifice type oil damper is used in which a part of a flow path is narrowed and a resistance force is generated by pressure loss when flowing oil.

As the orifice type, there can be used a fixed orifice having a fixed throttle area and a variable orifice type whose area changes according to the flow rate. In the fixed orifice, the area of the flow path is constant, and the resistance force is generated in proportion to the square of the flow rate, that is, the square of the piston speed. On the other hand, as shown in FIG. 8, the variable orifice is provided with a valve provided in the orifice portion to increase the flow area when the flow rate is increased and to make the flow easier. This is because, as the flow rate increases, the pressure P increases, and the spring is pushed up to widen the flow path.

FIG. 7 shows an example in which the effect of the present embodiment is calculated by using a typical boiler apparatus. As shown in FIG. 7, in the embodiment, the seismic response amount (response layer shearing force) is reduced particularly in the lower half of the supporting steel frame. As the effect of reducing the shearing force of the response layer, the weight of the supporting steel frame and the concrete foundation can be reduced, and there is a resource saving effect.

[0020]

The effect of reducing the amount of seismic response when the present invention is implemented is not uniform due to boiler capacity, ground conditions, predicted seismic force level, etc., but as shown in the above embodiment, The reduction in the seismic response of the boiler body (maximum bending moment) or the seismic response of the supporting steel frame (response layer shear force) is clearly observed.

According to the present invention, the amount of seismic response of the boiler device can be reduced, the reinforcing members of the boiler main body, the supporting steel frame members and the foundation concrete can be reduced in weight, and there is an effect of saving resources.

[Brief description of the drawings]

FIG. 1 is a view showing a boiler support structure and a boiler vibration control support structure according to the present invention.

FIG. 2 is an example of an arrangement of a connecting device according to the present invention.

FIG.

FIG. 4 is a diagram showing the structure and characteristics of an oil snubber used as a connecting device in the present invention.

FIG. 5 is a distribution diagram of a bending moment generated by the seismic response of the boiler body showing the effect of the present invention.

FIG. 6 is a characteristic diagram of an oil damper used as a connecting device in the present invention.

FIG. 7 is a distribution diagram of layer shear force generated by a seismic response on a supporting steel frame showing the effect of the present invention.

FIG. 8 is a schematic diagram of an oil damper used as a connecting device in the present invention.

FIG. 9 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Support steel frame, 2 ... Boiler main body, 2a ... Fire furnace part, 2b ...
Cage, 3 ... hanging rod, 4 ... seismic tie, 5
... connecting device, 6 ... piston, 7 ... valve.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-U 2-62205 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F22B 37/24

Claims (3)

(57) [Claims] 1. A supporting steel frame for supporting a boiler main body, a suspending member suspended from the supporting steel frame for suspending and supporting the boiler main body so as to allow expansion and contraction by heat, a suspended boiler main body and a supporting steel frame. And a seismic tie for limiting the relative displacement between the two when the earthquake occurs within a limit, wherein the furnace part and the cage part of the boiler body are provided. The furnace part and cage
Resistance to slow relative displacement due to heat with the
Generates drag or generates no resistance, and an earthquake occurs
Generates large resistance against sudden relative displacement
Characterized in that they are connected by a connecting device configured as described above.
Ira's seismic control structure. 2. A supporting steel frame for supporting a boiler main body, a suspending member suspended from the supporting steel frame for suspending and supporting the boiler main body so as to allow expansion and contraction by heat, a suspended boiler main body and a supporting steel frame. in seismic damping support structure of the boiler provided with a seismic ties are limits supporting the relative displacement of both the event of an earthquake within the limits provided between the cage portion of the <br/> boiler body (or furnace section ) Is provided as a base, and a connecting device is provided which is connected to vertices provided in the furnace part (or cage part) of the boiler body from both ends of the base to form two sides of a triangle , and the connecting device is connected to the furnace part. Cage and
Resistance to slow relative displacement due to heat
Or generate no resistance,
Generates a large resistance force against sudden relative displacement
Damping support structure of the boiler, characterized by being configured to. 3. An apparatus according to claim 1 or 2, vibration control supporting structure of the boiler to the coupling device is characterized in that a damping mechanism type coupling device which absorbs the seismic energy.