JP2770875B2 - Boiler seismic support method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for alleviating vibration of a structure having a support frame, and more particularly to an earthquake-resistant support method suitable for a suspended boiler.

[0002]

2. Description of the Related Art A boiler used in a thermal power plant or a garbage disposal plant cannot restrict the strength of a wall composed of a water pipe so much that the capacity of a self-supporting type is limited, and the thermal expansion of a furnace is released downward. Therefore, a suspended boiler that is suspended and supported from a support frame of a boiler frame has been frequently used. Since the suspended boiler has a structure in which a heavy body is suspended, the boiler body and the boiler frame behave differently during an earthquake, so that measures against relative vibration with the frame are required. In addition, a support device for connecting the boiler frame and the boiler requires a measure against thermal expansion of a member caused by a temperature change of the boiler.

FIG. 4 is a schematic diagram showing a state in which a seismic tie, which is a conventional typical seismic support method, is applied to a suspended boiler. As shown in FIG. 4, a backstay is mounted horizontally on the outer surface of the boiler wall formed by welding the water tube tubes into a single plate to form a reinforcing member. A male stopper beam is attached to each part of the backstay. A supporting frame made of steel is horizontally arranged at a height position corresponding to the backstay on the boiler frame, and a female receiving structure is mounted at a position facing the male stopper beam. The male stopper beam is inserted into the female receiver to support the horizontally moving load. Such seismic ties are designed to have a small spacing of 2 to 4 mm between the beam and receiver to release the thermal expansion of the boiler and to suppress only the vibration caused by the earthquake by integrating it with the boiler frame. It is. Therefore, since the inertia force of the boiler is transmitted to the boiler frame as it is, the beam and the receiving member serving as a stopper are increased in size to maintain rigidity with the increase in the size of the boiler. It is necessary to drastically increase the number of members to be installed due to excessive force.

In Japanese Patent Publication No. 58-36245, a part of a beam or a receiver is provided with a section having a smaller cross-section than the other part and having a weaker lateral rigidity. A reinforcement device for a suspended boiler in which elasto-plastic deformation is generated to absorb excessive kinetic energy as plastic energy to enhance the vibration damping effect is disclosed. As a result, it is not necessary to increase the size of the stopper member even for a large boiler, and an economical reinforcing device can be provided. However, the seismic support method using these seismic ties has a small effect of suppressing the shaking because the earthquake motion is transmitted to the boiler main body as it is in an earthquake that does not reach the plastic deformation of the beam or the like. In addition, it is difficult to accurately set the load at which a beam or the like reaches plastic deformation, and in many cases, the expected effect on an earthquake is not exerted. In addition, when the load is concentrated, weak parts are generated in the boiler structure, so a large number of size ties are required to disperse the load, such as uncertainty of the effect, inaccuracy in design, large labor in construction, etc. There are several challenges.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a structure for supporting a boiler body of a suspended boiler in a seismic manner, by reducing the number of seismic support devices to be installed and reducing the reaction force . Another object of the present invention is to provide an easy design method.

[0006]

In order to solve the above problems, an earthquake-resistant support method according to the present invention is directed to a hanging boiler in which a boiler body is hung from above a boiler frame. Boyd almost horizontally between
The vibration of the boiler is suppressed by a vibration isolator having an energy absorbing function provided at each of the four corners at the upper end and the four corners at the lower end of the main body . It is more preferable that the vibration isolator has a damping force substantially proportional to the speed . Further , the vibration isolator may be inserted between the corner of the boiler main body and the column of the boiler frame.

According to the seismic support method of the present invention, the vibration isolator inserted between the hung boiler and the boiler frame dissipates the energy of the horizontal relative motion generated between the hung boiler and the boiler frame during an earthquake. Because of the absorption, the whole structure can be regarded as a soft vibration system, and the amplitude excited by the earthquake becomes smaller than when the conventional method is used, and the reaction force becomes smaller. In addition, the number of places where vibration isolators should be installed is greatly reduced, so that seismic support with excellent economic efficiency can be achieved.
In addition, the use of a vibration damper that has a damping force proportional to the speed among vibration dampers having an energy absorbing function, such as a hydraulic damper and a mechanical damper, simplifies the calculation of seismic design and enables a small computer The result can be obtained quickly. In particular, the effect when designing by simulation calculation is great. Also, the vibration isolators may be installed anywhere on the reinforcing member around the boiler. In particular, if one pair is provided at each of the four corners of the upper end and the lower end of the boiler body,
The vibration mode is simplified, and the calculation is further simplified. Further, the vibration isolator inserted between the concrete pillar provided at the corner of the boiler main body and the corner of the boiler frame can directly connect the boiler main body to the most rigid part in the boiler frame. Therefore, the anti-vibration effect is large. Further, the structure of the boiler frame can be simplified.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a suspension type boiler according to the present invention. FIG. 1 is a perspective view for explaining a hanging boiler seismic support method of the present invention, FIG. 2 is a partial plan view showing another example of an attached state at one corner of the boiler, and FIG. 3 is another example of an attached state. FIG. In FIG. 1, reference numeral 1 denotes a main body of a boiler to be subjected to seismic support, and 2 denotes a boiler frame. The boiler frame 2 is supported at four corners by reinforced concrete pillars 21 whose foundation is fixed on the ground, and a suspension frame 22 is fixed to the top. Several beams 23 are passed over the suspension frame 22, and the boiler 1 is suspended by a plurality of supports 24 provided for each of the beams 23. When such a supporting method is used, a large thermal expansion generated in the boiler main body due to a temperature difference between the time of stop and the time of operation escapes freely in the hanging direction, so that no special measures are required, so that the entire structure is simplified. The boiler 1 has a furnace part 11 and a economizer part 12, and the furnace part 11 occupies the main structural volume and weight.

A first reinforcing member 13 is wrapped around a peripheral edge at an upper end of the boiler 1, and a second reinforcing member 14 is wrapped around a peripheral edge near a lower end of the furnace part 11. Further, between the concrete columns 21 of the boiler frame 2, the first steel beam 2 having a larger outer circumference than the first reinforcing member at a height corresponding to the first reinforcing member 13 of the boiler.
5 also has a second height at a height corresponding to the second reinforcing member 14.
Second steel beam 26 having a larger perimeter than reinforcement member 26
Is spread over a square. Further, at each of the four corners of the first reinforcing member 13 and the second reinforcing member 14, an attachment for mounting a vibration isolator to which two vibration isolators can be attached is welded. On the other hand, an attachment for mounting a vibration isolator is welded inward to a position near each vertex of each of the two steel frames that intersect at each vertex of the corresponding first steel beam 25 and second steel beam 26. . If the top of the steel beam is far from the corner of the reinforcing member, it can be dealt with by providing a supplementary beam in the middle of the steel beam and attaching an attachment inside the top formed there. A vibration isolator 3 is mounted between the boiler-side attachment and the boiler frame-side attachment, and a total of 16 vibration isolators are used, two at each corner. Each vibration isolator 3 is mounted substantially perpendicular to the steel beam, and has a structure in which the corners of the first reinforcing member 13 and the second reinforcing member 14 are supported from the boiler frame. The vibration isolator 3 is an oil damper having a function of absorbing kinetic energy, and the damping force is proportional to the speed at which the distance between the mounting portions at both ends changes.

The object to which the seismic isolation support method of the present invention is applied is
A suspended boiler that supports a boiler body weighing 4000 tons by suspending it from above with a boiler frame having a height of 100 m. The boiler has a frequency of 0.18 Hz in one horizontal direction and a frequency of 0.18 Hz in a horizontal direction perpendicular thereto. It has a vibration mode with a main natural vibration of 20 Hz. If this suspended boiler is to be seismically supported by a conventional size tie, it is necessary to reduce the load per unit by dispersing the load so as not to cause structural strain. Therefore,
A large number of back stays must be provided on the outer wall of the boiler main body, and a large number of stoppers must be arranged thereon. This has the disadvantage that the weight of the boiler becomes excessively large in addition to the difficulty in construction. In addition, since it is difficult to accurately set the load at which the beam reaches plastic deformation, it is liable to increase the design margin and install a larger number of size ties.
Furthermore, in a small earthquake, the ground motion is transmitted to the boiler body as it is, and the effect of suppressing the shaking is small. Further, the hanging type boiler is mounted on the above-mentioned boiler by using a supporting device having a solid spring.
Attempting to support at two support points, even if the maximum displacement at the support point is allowed up to 400 mm, 200 t at each point
Must withstand the reaction forces of For this reason,
It is necessary to increase the strength of the boiler or strengthen the structure of the reinforcing member such as a backstay. Alternatively, the number of support points must be increased to reduce the reaction force per support device.

However, according to the seismic isolation support method using a vibration isolator having an energy absorbing function, the horizontal movement of the boiler excited during an earthquake is effectively suppressed. The damping rate when the vibration of the boiler is attenuated by the function of the vibration isolator is 0.2
6 and the maximum displacement at the support points is suppressed to 300 mm, the reaction force at the above-mentioned 16 support points is only 25 t, which can be sufficiently dealt with by a relatively small oil damper or the like that is commonly used. Further, since the reaction force acting on the boiler main body via the vibration isolator is small, the load on the structure supporting the vibration isolator is also small. As described above, the seismic support structure of the suspended boiler to which the seismic support method of the present invention is applied can sufficiently suppress a dangerous vibration state by absorbing a small reaction force with a small number of vibration isolators. ,
Not only is the cost of the vibration isolator as a whole reduced, but also the reinforcement structure of the boiler body is significantly simplified, and the weight is reduced accordingly.

The specifications of the suspended boiler to which the present invention is applied are merely typical examples, and the damping rate, displacement, load, and the like can be selected according to conditions. Further, it is needless to say that the present invention can be applied to smaller boilers and larger boilers within the scope of design change. In the above, in order to explain the method of the present invention, a vibration isolator having an energy absorbing function that represents a damping force proportional to the displacement speed between the mounting positions is used, but the two have a linear relationship. If the damping force has an increasing function with respect to the speed, it goes without saying that the method can be used in the method of the present invention. Although the embodiment has been described using an oil damper, the vibration isolator used in the seismic isolation support method of the present invention may be any type having an energy absorbing function, such as a mechanical damper or a friction damper, other than the oil damper. Vibration absorbers can also be used.

In addition, the description has been given of the configuration in which the two vibration isolators arranged at the respective corners are connected to the steel beam spanned between the concrete columns, but as shown in FIG. The vibration isolator attachment 27 may be directly attached, and the vibration isolator 3 may be inserted between the attachment 27 and the attachment 15 welded to each corner of the reinforcing members 13 and 14 on the boiler side. When the vibration isolator 3 is directly supported by the columns 21 as described above, it is not necessary to provide a function of supporting the vibration of the boiler to the steel beam passed between the columns. Therefore, the boiler frame structure can be simplified, and in some cases, the steel beam can be omitted. As shown in FIG. 3, an attachment 27 for mounting a vibration isolator is installed at a position facing the corners of the boiler reinforcing members 13 and 14 inside the column 21, and an attachment 15 attached to the reinforcing member is attached to the reinforcing members 13 and 14. If it is arranged at a position slightly away from the corner to the side and the extension line of the axis of the vibration isolator 3 inserted between both attachments passes through the rigidity of the column 21, the twist on the column 21 There is an advantage that the moment is reduced and the structural strength is increased. The cross-sectional shape of the column 21 of the boiler frame is not limited to a circle, but may be any shape. The material is not limited to concrete, and may be made of steel. Further, the same effect can be obtained when one vibration isolator 3 is provided for one support 21. In addition, the seismic support method of the present invention is applied not only to a suspended boiler but also to a support frame, since the same effect can be obtained by acting on a material that is excited during an earthquake and performs relative displacement movement with respect to a support structure. The same can be applied to a structure supported down.

[0014]

As described above, according to the suspension type boiler seismic support method of the present invention, it is possible to use a vibration damper of a type that absorbs energy, such as a hydraulic vibration damper, instead of the conventional size tie. By reducing the number of seismic support devices and reducing the reaction force, it has become possible to realize a more economical seismic support structure for a large suspended boiler.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a method for supporting a suspended boiler in an earthquake-resistant manner according to the present invention.

FIG. 2 is a partial plan view showing another example of mounting a vibration isolator in the method of the present invention.

FIG. 3 is a partial plan view showing still another example of mounting a vibration isolator in the method of the present invention.

FIG. 4 is a perspective view showing a conventional seismic support method for a suspended boiler.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler main body 2 Boiler frame 3 Vibration isolator 11 Furnace part 12 Energy saving part 13, 14 Reinforcement member 15 Attachment 21 Support post 22 Hanging frame 23 Beam 24 Supporting tool 25, 26 Steel beam 27 Attachment

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-296406 (JP, A) JP-A-58-72801 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F22B 37/24

Claims (3)

(57) [Claims] 1. A boiler main body is suspended from an upper end of a boiler frame, and one boiler main body is suspended substantially horizontally between a side portion of the boiler main body and the boiler frame at four corners of an upper end portion and four lower end portions of the boiler body.
With a vibration isolator with energy absorption function provided for each pair ,
A seismic support method for a suspended boiler, which suppresses vibration of the boiler. 2. The method of claim 1, wherein said vibration isolator is a vibration isolator having a damping force substantially proportional to a speed. 3. A process according to claim, wherein the vibration isolators are inserted between the posts of the corner and the boiler frame of the boiler body
3. The seismic support method of the suspended boiler according to 1 or 2 .