JPS5816104A - Waste heat recovering heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust heat recovery heat exchanger used in a combined cycle power generation plant, etc., and particularly relates to an exhaust heat recovery heat exchanger that promotes high efficiency and high operation rate of a plant. .

A combined cycle is a power generation system that increases plant efficiency by combining a gas turbine and a steam turbine, and a typical combined cycle is the exhaust heat recovery type. An exhaust heat recovery heat exchanger, which is a main component of an exhaust heat recovery type combined cycle power plant, is a heat exchanger that heats water and generates steam using the high-temperature exhaust gas of a gas turbine.

An example of an exhaust heat recovery heat exchanger will be described below with reference to FIG. 1.

High-pressure, high-temperature combustion gas produced by a combustor (not shown) flows into a gas turbine (1), rotates it at high speed, reduces pressure and temperature, and is discharged. Since the temperature of this exhaust gas is normally 500 to 600°C, it is extremely uneconomical to dispose of it as exhaust gas. For this reason, an exhaust heat recovery heat exchanger (2) was installed.
The high temperature exhaust gas of the gas turbine 11) is sent to the waste heat recovery exchanger (2) through the inlet duct (3). The exhaust heat recovery heat exchanger (2) is equipped with a plurality of heat exchange parts made up of a large number of heat transfer tubes inside the main body (4), and is a device that exchanges heat between water and exhaust gas by forced heat transfer. It is.

The exhaust gas that has entered the main body shell (4) flows upward and passes through heat exchange parts such as the evaporator (5) and the economizer (
6) and exits from the outlet duct (7) to a chimney (not shown).

Here, the evaporator (5) and the economizer (6) are constituted by a large number of heat exchanger tubes as described above, and steam and water flow inside the tubes. The inlet side of the economizer (6) is connected to the water supply pipe (8), and the -Yoshikawa outlet side is connected to the water supply pipe (8).
It is connected to the bottom of the steam drum (9). Further, the evaporator (4) communicates with the lower part of the steam drum (9) on the inlet side, and with the upper part of the steam drum (9) on the -Yoshikawa mouth side.

Further, a main steam pipe 00) is connected to the upper end of the steam drum (9), and the other end of this main steam pipe (1ω) is led to a steam turbine 01. In addition, a steam turbine (1
1), a condenser (121) is installed at one end. Note that here, the symbol αm indicates a denitrification device.

In the above configuration, the exhaust gas of the steam turbine (11) is evaporated and sent under pressure to the economizer (6) through the water supply pipe (8). The feed water heated by the economizer (6) flows into the lower part of the steam drum (9). The water in the steam drum (9) is drained, and the evaporator (5
), where it becomes steam through heat exchange with the exhaust gas mentioned above and returns to the upper part of the steam drum (9).

The steam in the steam drum (9) is extracted from the upper part of the steam drum (9) through the main steam pipe (101) and sent to the steam turbine (
11), where it expands to complete its work and flows into the condenser f121 again.

Now, when actually installing the exhaust heat recovery heat exchanger explained above, as shown in Figure 2, the evaporator (5), denitrification device (
+3), economizer (6), etc. are manufactured and assembled separately as one box-shaped unit, and then each unit is bolted together via a flange (16) to support the exhaust heat recovery heat exchanger as a whole. Install it on frame 09. In this case, the inlet duct (3) and the outlet duct (7) are also combined by the flange 06).

The exhaust gas flowing inside this exhaust heat recovery heat exchanger (2) is
As mentioned in 111, the temperature is 500 to 600°C,
Evaporator (5), denitrification device f131. Economizer (6)
When this exhaust gas directly hits the outer panel of the unit, which is a strength member that makes up each box-shaped unit and has a part of its strength, the temperature of the outer panel reaches 500"C, which is close to the exhaust gas temperature.
It will reach a high temperature. For this reason, 5
We use materials that have sufficient strength even under wet temperatures of around 00°C, can be used in high-temperature conditions for long periods of time, and have corrosion resistance against SOx and NOx contained in exhaust gas. Must be. As such material, high alloy steel such as stainless steel must be used.
Moreover, since it is used in a layer temperature range of 500°C, it is necessary to compensate for the decrease in high-temperature strength, and the thickness of the outer plate used as a strength member must be significantly increased. Such an exhaust heat recovery heat exchanger (2) has two drawbacks: it is expensive and inevitably increases in weight, and cannot be put to practical use. Therefore, in the exhaust heat recovery heat exchanger (2), it is not advisable to adopt an external heat retention system like a normal heat exchanger, so an internal heat retention system as shown in FIG. 3 is used.

That is, in this method, no heat insulating material is used inside to prevent the humidity of the outer panel (18) from becoming high. +1 and lagging decorations are attached via the support bin (21) and presser plate (22). In addition, lagging exposed to high temperature exhaust gas (21'll thermal expansion support bin (2+), skin 0
The difference in elongation between the lagging (20) and the lagging (20) is accommodated by making the diameter of the lagging (20) larger than that of the support bottle (21).

By the way, each unit such as the evaporator (5), as shown in Fig. heat exchanger tube 041 that performs heat exchange;
It is composed of a support plate (c) that supports the weight of the heat exchanger tube (24) and keeps the gap constant, and this support plate (c) allows the heat exchanger tube (24) to stretch in the longitudinal direction under heat tension. hinge (26) so as not to impede its thermal expansion when
However, when inserting the heat exchanger tube (2) into the exhaust heat recovery heat exchanger (2), or when transporting the assembled unit to the installation site, ,
In case there is a support board c! If 9 moves, the heat exchanger tube (24
) will not fit properly, making assembly impossible. Further, during transportation, the support plate (c) may shake together with the heat exchanger tube (24), and the welded portion where the heat exchanger tube (24) is attached to the header (23) may become cracked or damaged. For this reason, the support plate (251) is fixed to the outer plate (I mallet) with a rest stop (5) as shown in FIG. This rest stop (5) is connected to the outer plate (181 and the welded part (28b) by the supporting plate (25) and the welded part (28a).
), and at the time of final assembly, as shown in Figure 6, the part between the support plate (251 and the outer plate) is cut out, and finally the support plate (29 is made movable). .For this reason, when assembling each unit at the factory, the flange (16) of each unit is
The only option is to install a heat insulating material in the vicinity.

Furthermore, even during installation, after the upper and lower units are assembled, there is no space for a person to enter the inner surface of the flange f161, so it is not possible to carry out heat insulation work from the inner surface. Therefore, the flange after installation is completed (near 161 is the 6th
The structure is as shown in the figure, and there is no heat insulating material for high-temperature exhaust gas! The flow may flow directly to the N part where the force is broken, and this part may become hot and the structural strength may decrease, and in some cases, there is a risk that the area around the A part may be damaged due to the generation of local thermal stress. In addition, since the outer surface of the outer panel (18) also becomes high temperature, peeling of the paint on the outer surface of the entrance may cause damage to the outer panel (18).
There are also concerns about problems such as p-corrosion and corrosion of the inner surface due to direct contact with the exhaust gas. To solve this problem, as shown in Figure 7, the moisturizing material (1□□
□ and lagging (20 should be protruded from the top so that this part and the outer plate of the upper unit (181) can be fitted with a spigot). However, each unit should have a length of 15 to 20771 mm. Moreover, since it is a welded canned structure, it is almost impossible to manufacture it with high precision so that the total λ of the fitting part is 1 to 2.For this reason, conventional waste heat j[1] In the state shown in FIG. 6, the heat insulating material a9 was cut off at part A.

In consideration of the above-mentioned points, the present invention aims to provide an exhaust heat recovery heat exchanger that makes it possible to provide a heat insulating material even in parts that are interrupted during installation.

Hereinafter, an example of a willow tree according to the present invention will be explained using FIG. 8.

In Fig. 8, when the outer panel of the upper unit is used, heat insulating material (1!1) and lagging (2o) are attached to the inner surface using support pins (21) in the manner explained in Fig. 3. When the outer panel is attached, flanges (16) are attached by welding to allow access to the upper and lower uni-soto. On the other hand, like the upper unit, the lower unit has a heat insulating material θω and lagging ■ attached to its inner surface via support pins (211), and a flange (16) is welded to the inner surface. The inner surface of the section is kept warm by applying heat insulating material (3z
, and lagging C (31) are attached using the method shown in FIG.
It is kept warm by its effectiveness. And this heat retention segment)
(301 is inserted between the upper and lower flanges (I6),
The bolts (T) and nuts (T) are screwed together at the same time when the upper and lower units are assembled. The heat-retaining segment ζ■ according to the present invention is fabricated by being divided into longitudinal sections as shown in FIG. 9, and then assembled together at the time of installation. In addition, heat retention segment) (
The length of one of 3I is within a few meters.

Next, a method for assembling the exhaust heat recovery heat exchanger according to the present invention will be described. When assembling the upper and lower units, the heat retaining segment according to the present invention (Peng's heat retaining mounting board 01) is placed on the flange 00 of the lower unit. At this time, attach the heat retaining segment (A) to the flange a of the lower unit at the first light installation position (Y) shown by the two-dot chain line in Figure 8.
61 temporarily. In this state, the insulation mounting board (
There is a gap between 311 and the outer panel of the lower unit (18).At the same time, there is also a large gap between the outer panel of the upper unit [18] and the insulation material mounting board 31), so it is structurally difficult. Although it has a fitting structure, it does not pose a problem when fitting the flange housings of the upper and lower units, which have relatively low assembly accuracy.

After the heat insulating material mounting board G'D is sandwiched between the flanges 00, the positions of the upper and lower units are finely adjusted.

After that, pull the heat insulating material mounting board (3I) outward, and the heat insulating material mounting board 01) will be attached to the outer panels (3I) of the upper and lower units.
Insulating material (make sure that the surfaces of 3z are almost on the same surface. After that, attach Go) C35) and Natsu) (36) to the flange a of each upper and lower unit.
Fixed at θ. This makes it possible to keep the inner surface of the flan vf16) joint portion warmer, which has conventionally been unable to be kept warmer than the inner surface.

10 and 11 show other embodiments of the present invention.

Figure 10 shows a case in which a welded joint is used instead of a flange joint to connect the upper unit's outer plate (11'O) and the lower unit's outer plate 08. In the same way as in the case, the heat insulation segment (to) is attached, and then the heat insulation material mounting board Oυ is welded and fixed together with the outer plate α mallet during welding of the outer plate.Furthermore, in Fig. 11, the upper unit is attached to the flange. (16) is not used, but the heat insulation mounting board (31) is welded and used as a flange.The overall assembly in this case is similar to the previous example, where the heat insulation segment (301) is attached to the flange of the lower unit. (After temporarily fixing it to 161, temporarily fixing the upper uni-soto,
After adjusting the position, fix with bolts C (S and Natsu) C361, and finally weld (3η, C38). Furthermore, the heat insulation segment according to the present invention is manufactured by dividing it in the hand direction,
As shown in Fig. 12, a dividing line r38) is generated in the direction perpendicular to the long plane direction due to assembly. According to the method shown, it is possible to completely seal the internal fluid and provide internal heat insulation at the joint.

As described above, according to the present invention, each unit of the exhaust heat recovery heat exchanger has a normal manufacturing error of 1 to 2 rn for a length of 15 to 20 m, which does not result in high manufacturing accuracy. It is possible to apply internal heat insulation to the joint surfaces of the exterior panels during installation and final assembly, which can cause the exterior panels of each unit to become hot, reducing their structural strength and preventing corrosion due to peeling of the exterior paint. , and can effectively prevent corrosion of the inner surface due to direct contact with exhaust gas.

[Brief explanation of the drawing]

Figure 1 is a schematic system diagram of an exhaust heat recovery type combined cycle power generation plant, Figure 2 is an elevational view of a conventional exhaust heat recovery heat exchanger, Figure @3 is a sectional view to explain the internal heat retention method, 4
The figure is a block diagram of a conventional unit such as an evaporator.
A sectional view showing the lower flange portion of the unit shown in the figure,
Figure 6 is a sectional view of the flange joint of the upper and lower units, Figure 7
The figure is a cross-sectional view showing an example of a unit using the internal heat retention method, Figure 8 is a cross-sectional view showing the main parts of the waste heat recovery heat exchanger according to the present invention, and Figure @9 is a cross-sectional view showing the main parts of the exhaust heat recovery heat exchanger according to the present invention. 10 and 11 are sectional views showing other embodiments of the present invention, and FIG. 12 is a plan view of a portion corresponding to FIG. 11. (5)...Evaporator (6)...Economizer tll? l 10. Outer panel (301・
・Thermal insulation segment (31)・・・Thermal insulation mounting board
C3Z...Insulating material +331...Lagging
@...Support pin]/(351...Bolt (
36)...Nut C37), C candle...Welding Fig. 1 Fig. 2 Fig. 1 Fig. 5 M6 Fig. 20 /q 2/ ○0 7□ ○○ ■ 6 2.5 /6 10゛' 2/ /8 Figure 9 Figure 10

Claims (1)

[Claims] It has a plurality of heat exchange parts provided along the flow direction of exhaust gas from the bottom to the top, and suppresses the outer plate of each unit facing the heat exchange part from coming into direct contact with the flow of exhaust gas. In the case where a heat insulating material is provided in the current part, the heat insulating material provided in each unit joint part that accommodates the heat exchange section is divided into an appropriate number of heat insulating segments in the direction along the flange joint surface of the unit, but The divided heat retention segments are provided with lagging, which is provided via a support pin at one end of the T-shaped heat retention mounting board that constitutes the main body.
and a heat insulating material, the other end of which is integrally provided to the flange portion of each unit by a fastening member or by welding.