JPH04124501A - Exhaust heat recovery boiler - Google Patents

Abstract

PURPOSE:To prevent the heat transfer performance of an exhaust heat recovery heat exchanger from getting reduced because of a short path by providing a deviation means for controlling the flow of a fluid outside of pipe between heat transfer pipes that have the same flow channel cross section and are provided in parallel. CONSTITUTION:When the exhaust heat gas that is a fluid outside of pipe flows from the front face to the rear face of a heat transfer pipe panels which consist of many heat transfer pipes 11, the exhaust gas tries to flow through the space between the two heat transfer pipe panels that have the same flow channel cross section and are provided in parallel. This exhaust gas is blocked by the wall face of a deflection cover 23 in the front face and its flow direction is changed to the outside and is guided by the deflection cover 23 and panel side plates 22a and 22b that follow the cover 23 and led to an adjacent heat transfer pipe 11. It is thereby possible to prevent the exhaust gas from flowing via the space where the heat transfer pipes 11 are not provided with having nothing to do with heat exchange. Afterwards, the exhaust gas that reaches the deflection cover 23 on the rear face through a second stage heat transfer panels is forced to change its flow direction to flow inside along the wall face and both flows merge and are led to a heat transfer panels on the downstream side.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an exhaust heat recovery boiler, and in particular, to a method for preventing a short pass of extra-tube fluid used for heat exchange with feed water. The present invention relates to a suitable waste heat recovery boiler.

(Prior technology) An exhaust heat recovery boiler receives high-temperature exhaust gas from natural engines, gas turbines, etc. as a heat source fluid, and recovers heat by exchanging heat with a low-temperature medium, that is, feed water, flowing in heat transfer tubes. It is known as a large-sized heat exchanger that aims to achieve this, and the one used in the gas-steam combined cycle power generation bran 1 is a typical example. A natural circulation type exhaust heat recovery boiler, which is a typical example of this large-sized exhaust heat recovery boiler, will be explained with reference to the drawings.

In FIG. 5, a high-pressure heat exchanger group consisting of a superheater 2, a high-pressure evaporator 3, and a high-pressure economizer 4, a low-pressure evaporator 5, and a low-pressure economizer 6 are contained in a heat exchanger body L extending horizontally. A low pressure heat exchanger group consisting of: The high-pressure system is equipped with a high-pressure steam drum 7, and the low-pressure system is equipped with a low-pressure steam drum 8. These steam drums 7.8 are arranged in the upper part of the heat exchanger shell 1. In the figure, reference numeral 9 indicates a denitrification device, which removes nitrogen oxides contained in exhaust gas by catalytic action.

On the other hand, FIG. 6 shows details of the high-pressure evaporator 3 as a representative of each heat exchanger. Each heat exchanger tube 11 is oriented vertically,
Both ends thereof are brought together so as to communicate with the upper header 12 and the lower header 13, forming a heat exchanger tube panel. Further, a heat insulating material 15 is placed on the inner surface of the body plate 14 to prevent the temperature of the body plate 14 from rising significantly from the atmospheric temperature. Furthermore, the length of the heat exchanger tube 11 is 1
In a large heat exchanger tube panel of more than 0 meters, the upper and lower headers 12, 13 alone cannot support the heat exchanger tubes 11, so the intermediate portion thereof is supported by an intermediate support 16. As shown in FIG. 7, through holes 17 are bored in this intermediate support 16 in accordance with the arrangement of the heat exchanger tubes 11.
is provided, and each heat exchanger tube 11 is inserted therethrough to increase the rigidity of the heat exchanger tube panel. This heat exchanger tube panel with increased rigidity is fixed to the body plate 14 via an upper bracket 18 and a lower support member 19 shown in FIG.

The above-mentioned high-pressure system superheater 2, high-pressure evaporator, and high-pressure economizer 4 as well as the low-pressure system low-pressure evaporator 5 and low-pressure economizer 6
is constructed by combining a plurality of such heat exchanger tube panels.

By the way, although Figures 6 and 7 show one heat exchanger tube panel placed in the same cross section of the flow path, when two heat exchanger tube panels are placed in the same cross section of the flow path, Figures 8 and 7 are used. The result is as shown in FIG.

Here, the configuration of each heat exchanger tube panel is shown in FIGS. 6 and 7.
It is the same as the one in the figure, and the explanation will be omitted.

(5 Problems to be Solved by the Invention) In recent years, in gas-steam combined cycle power plants in which this type of exhaust heat recovery wheel is incorporated, with the advent of large-capacity gas turbines, the size of equipment has become noticeably larger.
A method of arranging two heat exchanger tube panels in the same flow passage cross section, which allows the gas passage width of the heat exchanger body 1 to be widened, is becoming popular. In this case, as shown in FIGS. 8 and 9, an area where the heat exchanger tubes 11 are not placed, that is, a space 20, is created between the two heat exchanger tube panels.
There is a possibility that a so-called short bus occurs in which the exhaust gas flows to the heat exchanger tube panel on the downstream side without passing around the heat exchanger tubes 11. The exhaust gas flowing as a short bus makes it impossible to exchange heat with the feed water or steam passing through the heat transfer tube 11, and if this flow increases, the heat transfer performance of the waste heat recovery boiler will be greatly impaired. It gets lost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an exhaust heat recovery boiler that prevents a short bath of extra-tube fluid between heat transfer tube panels arranged in parallel in the same flow path cross section.

[Structure of the Invention] (Means for Solving am!) In order to solve the above-mentioned problem A waste heat recovery boiler comprising at least two heat exchanger tube panels arranged in parallel, characterized in that a deflection means for controlling the flow of fluid outside the tube is provided between the heat exchanger tube panels arranged in parallel in the same flow path cross section. That is.

(Operation) The exhaust gas guided to the heat exchanger body tries to flow between the heat exchanger tube panels arranged in parallel in the same flow path cross section. The deflection means provided at a position that closes the space between both heat exchanger tube panels obstructs the flow of this exhaust gas with its wall surface and directs the flow in the direction in which the heat exchanger tubes are lined up. As a result, the exhaust gas is guided to the side of the heat exchanger tube, and is guided to the heat exchanger tube panel on the downstream side while exchanging heat with the fluid inside the tube. That is, it is possible to prevent heat exchange from being impossible due to a short bus occurring between the heat transfer tubes.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 3. In Fig. 1 and Fig. 2, each heat exchanger tube 1
1 is arranged upright in a flow path through which exhaust gas and the like flow, and the heat exchanger tube panel which is an assembly thereof is divided into three rows to form one panel. An intermediate support 16 is arranged in each of the heat exchanger tube panels. As shown in FIG.
A plurality of heat exchanger tube panels are installed at important points in the heat exchanger tube panel, increasing the rigidity of the heat exchanger tube panel. A deflecting means 21 that always directs the exhaust gas toward the heat exchanger tubes 11 along the axial direction of the heat exchanger tubes 11 is provided between two heat exchanger tube panels arranged in the same flow path cross section.

This deflection means 21 consists of a pair of panel side plates 22 having a U-shaped cross section.
g, 22b, and a deflection cover 23 having a U-shaped cross section and covering the front surfaces of the panel side plates 22a, 22b. Here, the panel side plates 22a, 22b are fitted between two retaining plates 24a, 24c fixed to the intermediate support 16, and the panel side plates 22b are fitted between two retaining plates 24b fixed to the intermediate support 16, 24d, and supported by bolts 25 so as to be movable in a horizontal plane. On the other hand, the deflection cover 23 has panel side plates 22g, 22
b is fixed with bolts 27 using presser plates 26a and 26b. In this embodiment, in which the heat exchanger tube panels are arranged in two stages in the front-rear direction, the second stage heat exchanger tube panels are also provided with deflection means 21, and in this case, the deflection covers 23 are arranged in opposite directions.

The overall arrangement of the deflecting means 21 can be understood from the enlarged perspective view of FIG. 3.

Next, the operation of the above configuration will be explained with reference to FIG. 4. When exhaust gas, which is an extra-tube fluid, flows from the front to the rear of a heat exchanger tube panel made up of a large number of heat exchanger tubes 11, the exhaust gas also tends to flow between two heat exchanger tube panels arranged in parallel in the same flow path cross section. . This exhaust gas is blocked by the wall surface of the front deflection cover 23, and the direction of the flow is changed to the outside.
2b and toward the adjacent heat exchanger tube 11. This can prevent the exhaust gas from flowing through the space 20 (see FIG. 9) where the heat exchanger tubes 11 are not arranged without participating in heat exchange. After that, the exhaust gas that has passed through the second-stage heat exchanger tube panel and reached the rear deflection cover 23 is redirected inward along the wall surface, and the two merge and are guided to the downstream heat exchanger tube panel. It will be destroyed.

On the other hand, since there is a difference in the amount of heat received from the exhaust gas between the two stages of heat exchanger tube panels in the front and back direction, a difference in expansion occurs between the two panels during thermal expansion. At this time, the deflection cover 23 provided on the first-stage heat exchanger tube panel and the deflection cover 23 provided on the second-stage heat exchanger tube panel are both shaped like thin plates bent into a U-shape, and each can be freely deflected inward. One side does not restrict the free thermal expansion of the other.

Furthermore, due to the above-mentioned difference in elongation, gaps may occur between the first-stage and second-stage heat exchanger tube panels at the continuation portions of both, but the U-shaped lines of the panel side plates 22a and 22b overlap each other, These gaps are closed, thereby preventing exhaust gas from deviating from the flow path and causing a flow that does not participate in the exchange of heat.

Thus, if the deflection means 21 in which the deflection cover 23, which is a thin plate bent into a U-shape, is installed on the front or rear surface of the panel side plates 22a and 22b is used, the difference in elongation due to thermal expansion that occurs between the front and rear heat exchanger tube panels can be reduced. To prevent the heat transfer performance of the waste heat recovery boiler from being impaired by suppressing the short bus of the extra-tube fluid between the heat transfer tube panels arranged in parallel in the same flow path cross section while absorbing the is possible.

[Effects of the Invention] As explained above, the present invention provides deflection means for controlling the flow of fluid outside the tubes between the heat exchanger tube panels arranged in parallel in the same flow path cross section. This has the excellent effect of effectively suppressing the flow to the downstream heat transfer tube panel through the gap between the heat exchangers and preventing the heat transfer performance of the waste heat recovery heat exchanger from deteriorating due to the short bath. play.

[Brief explanation of the drawing]

1 and 2 are a cross-sectional view and a longitudinal sectional view showing one embodiment of the exhaust heat recovery boiler according to the present invention, FIG. 3 is a perspective view showing details of the deflection means, and FIG. Such operation explanatory diagrams, FIG. 5, a configuration diagram showing an example of a conventional exhaust heat recovery boiler, and FIG. 6, and ji! FIG. 7 is a vertical cross-sectional view and a cross-sectional view showing a heat transfer tube panel of a conventional waste heat recovery boiler, and FIGS. 8 and 9 are a vertical cross-sectional view and a cross-sectional view showing a conventional heat transfer tube panel. l.--Heat exchanger body 11 Heat exchanger tubes 16 Intermediate supports 22g, 22b Panel side plates 23 ...Deflection covers 24a, 24b, 24c, 24d--Holding plate Fig.

Claims (1)

[Claims] In an exhaust heat recovery boiler in which at least two heat transfer tube panels each having a planar row of upright heat transfer tubes are arranged side by side in the same flow path cross section in the heat exchanger body, An exhaust heat recovery boiler characterized in that a deflection means for controlling the flow of extra-tube fluid is provided between the installed heat transfer tube panels.