JPH025203Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a waste heat recovery boiler, and particularly to a waste heat recovery boiler that has high earthquake resistance and can be manufactured at low cost.

<Prior art and its problems> There are two types of waste heat recovery boilers that recover heat in high-temperature combustion gas discharged from a gas turbine or the like: a horizontal type and a vertical type, depending on the arrangement of heat transfer tubes. Fig. 1 shows a horizontally installed type, and for a flue 7 arranged perpendicular to the boiler installation surface, a superheater 6, an evaporator 4, and an economizer 1 are arranged parallel to the boiler installation surface in order from the bottom.
They are arranged in this order. High-temperature gas G flows from the bottom of the boiler, heats it in the order of superheater 6, evaporator 4, and economizer 1, and then discharges it out of the system. In the figure, 2 is a boiler drum, 3 is a downcomer, 5 is a riser, 10 is a circulation pump, W is water supply, and S is steam. In order to increase the capacity of the horizontal boiler with the above configuration, the heat transfer surface of the heat transfer part of the boiler is Increased boiler load can be accommodated.

However, in a boiler with this structure, generally the waste gas G flows upward perpendicularly to the boiler installation surface, so regardless of the boiler capacity, it is necessary to install an exhaust gas inlet duct several meters square inside the installation frame with its axis horizontal. , increase the overall height of the boiler. In addition, a pedestal 8 with a height of several meters
Requires.

For this reason, the heavy heat transfer tube panels are placed on top of a pedestal whose installation level is several meters above the ground, so the center of gravity is higher than the ground, which is undesirable from an earthquake-resistant perspective. . At the same time, due to earthquake resistance considerations, it is necessary to use materials with high strength and large dimensions for the ducts, columns, and beams, which increases the product price. Furthermore, since the tubes of the heat transfer tube group are arranged horizontally, the natural circulation force of the boiler water due to the water head cannot be used, so there is a problem that a circulation pump must be provided.

Figure 2 shows the structure of a vertically installed waste heat recovery boiler. In this type of boiler, the flue 7 is arranged parallel to the boiler installation surface (floor surface), that is, horizontally, and the superheater 6, evaporator 4, and economizer 1 are installed in the flue in order from the waste gas inflow side to the boiler installation surface. Position the panel with the surface perpendicular to the In this type of boiler, the evaporator uses the natural circulation of boiler water, so it is necessary to use a large boiler with a height (H) of 10 m or more. Therefore, in order to increase the boiler capacity, it is not necessary to increase the number of bends in the heat exchanger tube (the number of bends per panel), which is advantageous in manufacturing. However, if the length of the hanging heat exchanger tubes is increased, the height H of the flue 7 will increase, causing problems such as buckling of the flue 7 itself and insufficient vibration during an earthquake. In other words, by using a long tube, the ratio of the height H to the width D of the flue 7 becomes large, and as shown in Fig. 5, the center of gravity of the device is located more than 5 m above the bottom of the boiler. In order to shorten the construction period by dividing the heat transfer tube group of the boiler into multiple units, assembling them at the factory and transporting them to the site using a dolly, as shown in Figure 5, the floor of the dolly is pulled out from the unit after being delivered to the site. It requires a foundation with a height of approximately 1.2 m above the ground surface, and as the center of gravity is increasingly higher than the ground surface, earthquake resistance decreases. On the other hand, for a boiler with a large capacity, increasing the depth (flow direction) dimension (increasing the number of panels) without changing the height H and width D will configure each of the superheater, evaporator, and energy saver. By increasing the number of bends in a unit heat transfer tube, the heat transfer area of each tube may be increased, which increases the resistance of combustion gas flow, increases the blower outlet pressure, and increases the , the temperature of the outlet fluid of each of the evaporator and economizer changes, that is, the design conditions change, so it cannot be adopted.

<Purpose of the invention> In view of the above-mentioned problems, the purpose of the invention is to provide a boiler that has high earthquake resistance and can use long heat exchanger tubes.

<Summary of the Means> In short, this idea consists of heat transfer parts such as economizers, evaporators, superheaters, etc., with an inlet header whose axis is approximately vertical, and an outlet header which are arranged in multiple approximately horizontal lines. Connected and formed by panels consisting of heat transfer parts bent in parallel,
Earthquake-resistant waste heat constructed by making the panel surface perpendicular to the almost horizontal flow of waste gas in the flue, and connecting a downcomer pipe hanging down from a drum corresponding to the evaporator and an evaporator inlet header via a circulation pump. It is a recovery boiler.

<Example> An embodiment of this invention will be described below.

In FIG. 3, the flue 7 is arranged parallel (horizontally) to the boiler installation surface, and the width D is larger than the height H. This flue 7
A superheater 6, an evaporator 4, and a energy saver 1 are arranged in this order from the waste gas G inflow side. All of the heat transfer tubes constituting each of these heat transfer surfaces are arranged parallel to the boiler installation surface. By arranging the heat exchanger tubes in this way, it is possible to use long heat exchanger tubes corresponding to the width D of the flue 7, and the number of bends of the heat exchanger tubes per unit heat transfer area of the panel can be reduced, so the manufacturing of the heat exchanger tubes is possible. Costs can be reduced. However, since the heat transfer tubes are arranged horizontally, a circulation pump for boiler water is required.

FIG. 4 shows the relationship between the shape of the flue 7 and the manufacturing cost index of the boiler disposed within the flue. First, the shape of the flue 7 is shown as the ratio of the height H to the width D of the flue 7. In addition, the manufacturing index refers to the fluctuation state of material costs, processing costs, etc. due to changes in the number of bends and length of heat exchanger tubes shown in Figure 3, and the amount of material used for the flue, depending on the shape of the flue 7. shows. Here, if the manufacturing index when the ratio D/H is 1 is 100, then as D/H increases, the manufacturing index decreases and becomes the lowest when D/H is about 5, and then D/H As the temperature rises, the horizontal length of the heat exchanger tube increases, and the manufacturing index increases because the cost of components such as supports and mounting frames to prevent the heat exchanger tube from sagging (curving) increases. For these reasons, the D/H of the boiler flue 7 is between about 2 and 8, preferably between 4 and 6.

Next, the shape and seismic resistance of the flue are shown in FIG. 5, which schematically shows a cross section of the flue corresponding to FIG. 2, and FIG. 6, which schematically shows a cross section of the flue corresponding to FIG. 3. In the figure, GR indicates the center of gravity of the flue, KW indicates the stress in the lateral direction, and W indicates the stress in the direction of gravity. _H1 ,
H ₂ represents the height from the bottom of the flue to the center of gravity GR when the stress is applied. As is clear from the figure, there is a risk of collapse due to the stress KW in the vertically long flue shown in Figure 5, that is, with a large H ₁ /D ₁ .
As shown in Figure 6, there is little risk of collapse in a flue with a small H ₂ /D ₂ ratio. Figure 7 shows H ₁ /D ₁ or H ₂ /
The relationship between D ₂ and seismic intensity is shown, where range A shows the stable range of flue 7, and range B (shaded area) shows the range where overturning force occurs.
This figure also shows that a flue with a small H ₂ /D ₂ as shown in Figure 6 has higher earthquake resistance.

<Effect of the invention> By implementing this invention, a heat exchanger tube panel consisting of horizontal tubes with an appropriate D/H value can be formed, and the length from one bend of the horizontal heat exchanger tube to the next bend can be changed. The heat transfer area can be increased without increasing the number of bends, and the position of the center of gravity from the bottom of the duct does not need to be changed, which reduces manufacturing costs and lowers the center of gravity of the heat exchanger tube group. It is possible to form a waste heat recovery boiler with high earthquake resistance.

[Brief explanation of drawings]

Figure 1 is a perspective view of a horizontal waste heat recovery boiler, Figure 2
Figure 3 is a perspective view of a vertically installed waste heat recovery boiler, Figure 3 is a perspective view of the waste heat recovery boiler according to this invention, Figure 4 is a diagram showing the relationship between boiler manufacturing cost index and flue shape,
Fig. 5 is a diagram showing the deformed state of the flue, which is a schematic cross-section of the flue corresponding to Fig. 2, and Fig. 6 is a diagram showing the flue deformation state, which is a schematic cross-section of the flue corresponding to Fig. 3. The drawing showing the deformed state, FIG. 7, is a diagram showing the relationship between the seismic intensity and the flue shape. 1... Energy saver, 4... Evaporator, 6... Superheater,
7... Flue, H... Flue height, D... Flue width.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Heat transfer parts such as energy savers, evaporators, superheaters, etc. are arranged in a plurality of substantially horizontally parallel inlet headers and outlet headers whose axes are approximately vertical. A downcomer pipe and an evaporator inlet header are connected to each other by a panel made of bent heat transfer tubes, with the panel surface perpendicular to the substantially horizontal flue gas flow, and a downcomer pipe and an evaporator inlet header are suspended from a drum corresponding to the evaporator. An earthquake-resistant waste heat recovery boiler characterized by being connected via a circulation pump. 2. In the earthquake-resistant waste heat recovery boiler described in claim 1 of the utility model registration claim, the width D and height H of the flue
An earthquake-resistant waste heat recovery boiler having a ratio of 1 or more, preferably 2 to 8.