JPS62221425A - Denitration device - Google Patents

Abstract

PURPOSE:To prevent off-gas not yet treated from leaking and enhance denitration performance by providing reinforcing plate on the outer circumference of catalyst blocks piled up in an off-gas line and making a seal structure. CONSTITUTION:A denitration device is provided in an off-gas line 2, where catalyst blocks 23 are piled up. Each of catalyst units 22 of catalyst blocks 23 is covered with a reinforcing plate 28a at the ceiling, a reinforcing plate 28b on the left side face, a reinforcing plate 28c on the right side face and a reinforcing plate 28d at the bottom, and sealed with seal welding section 29. Also the reinforcing plate 28a is seal welded with a catalyst block frame 24 and a V-shaped plate at the seal welding section 29. By said seal structure, gas not yet treated is prevented from leaking and denitration performance is enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a denitrification device for removing nitrogen oxides (NOx) from combustion exhaust gas discharged from a waste heat recovery device of a combined cycle power plant, and in particular, This relates to a denitrification device in which water flows horizontally.

[Conventional technology]

Large-capacity thermal power plants are being constructed to meet the rapidly increasing demand for electricity, but these boilers are required to operate at variable voltage in order to obtain high power generation efficiency even during partial loading.

This is a feature of recent electricity demand, as nuclear power generation increases, the difference between maximum and minimum loads increases, and thermal power generation tends to shift from base load to 9 load adjustment.

In other words, there are few thermal power generation boilers that are always operated at full load; instead, they are operated with the load raised or lowered to 75% load, 50% load, 25% load, or the boiler is operated at full load. So-called daily startup and shutdown (D
aily 5tart 5top (hereinafter simply referred to as DSS) and weekend startup/stop (WeeklyStart 5top)
In order to improve the power generation efficiency, the power generation efficiency is improved by carrying out the intermediate load by carrying out the S top (hereinafter referred to as single KWSS) operation.

For example, combined cycle power plants have recently been attracting attention as a part of high-efficiency power generation. This combined power generation plant first generates electricity using a gas turbine, and then recovers the heat in the exhaust gas discharged from the gas turbine using a waste heat recovery device (waste heat recovery boiler). It drives a steam turbine to generate electricity.

This power generation plant uses gas turbines to generate electricity and steam turbines to generate electricity, so it has high power generation efficiency, and the gas turbine has excellent load responsiveness, so it can sufficiently respond to sudden increases in electricity demand. It also has the advantage of excellent load followability, making it especially effective for KDSS and WSS operations.

However, in this combined power generation plant, LNG,
Since clean fuel such as kerosene is used, the amount of 5OXt and dust is reduced, but the amount of oxygen and high temperature combustion in gas turbine combustion increases the amount of Noxt in the exhaust gas, so it is necessary to use a denitrification device. A built-in waste heat recovery boiler has been developed.

FIG. 6 is a schematic diagram of a combined power generation plant in which a denitrification device is installed. In FIG. 6, 1 is a gas turbine, 2
3 is a superheater, 4 is a first evaporator, 5 is a denitrification device, 6 is a second evaporator, and 7 is an economizer. The superheater 3 , first and second evaporators 4 and 6 , denitrification device 5 , and economizer 7 are arranged within the exhaust gas passage 2 . 8 is a drum that generates steam.

9 is a steam turbine driven by the steam generated in the drum 8; 10 is a condenser that condenses the steam and returns it to water; 11 is a condensate pump that supplies water from the condenser 10 to the drum 8; 12 is a water supply It is a conduit.

The water in the condenser 10 is turned into water supply W by the condensate pump 11, passes through the water supply pipe 12, is preheated by the exhaust gas GK in the economizer 6, and is supplied into the drum 8. The water in the drum 8 is transferred to the downcomer pipe 1
3 and descends through pipes 14a and 14b to the evaporator 4.
．． 6 and returns to the drum 8 via pipes 15a and 15b. In this way, during the circulating flow, the evaporator 4,
The steam generated by heat exchange with the exhaust gas G in step 6i is introduced into the superheater 3 through the saturated steam pipe 16, where it is transferred to the exhaust gas G.
The superheated steam is supplied to the steam turbine 9 via the main steam pipe 17 as superheated steam. 18 is connected to the main steam pipe, bypassing the steam turbine 9 and directing the steam to the condenser 10
This is the turbine bypass pipe that leads to the Further, 19 is a steam turbine control valve that adjusts the flow rate of steam to the steam turbine 9;
20 is a turbine bypass valve that adjusts the amount of steam bypassed depending on the amount of steam supplied to the steam turbine 9; 21 is a damper for the exhaust gas duct 2;

The above explanation is an overview of combined cycle power plants, but in general,
Inside the exhaust heat recovery gay 2, a denitrification device 5 is disposed, which includes a superheater 3, evaporators 4, 6, and a carbon saver 7, and which recovers heat from exhaust gas and denitrates the exhaust gas.

FIG. 7 is a longitudinal sectional view of a conventional denitrification device, FIG. 8 is a perspective view of a conventional catalyst block, and FIG. 9 is a side view of the catalyst unit of FIG. 8.

7 to 9, 2 is an exhaust gas passage, 5 is a denitration device, 22 is a catalyst unit, 23 is a catalyst block, 24
25 is the catalyst block frame, and 25 is the ■ template.

26 is a gap, and 27 is a space.

The catalyst block 23 is attached to the catalyst block frame 2 as shown in FIG.
The denitrification device 5 is constructed by stacking catalyst units 22 in the exhaust gas passage 2 and stacking the catalyst blocks 23 in the exhaust gas passage 2 as shown in FIG.

On the other hand, as shown in FIG. 8, the catalyst block frame 24 is a support for the catalyst unit 22,
■ Template 2 is installed between the catalyst units 22 for the purpose of increasing strong deformation.
5 is placed. In addition, a space is provided between the templates 250 in order to reduce the weight and cost efficiency of the catalyst block 23.

[Problem that the invention seeks to solve]

However, as mentioned above, these combined cycle power plants and boiler plants frequently start and stop due to DSS operation or WSS operation. Catalyst unit 2 to be heated unilaterally
2 expands, and when the operation is stopped, it contracts back to its original position, ~・
The so-called catalyst unit 22 repeats expansion and contraction.

On the other hand, as shown in FIG. 9, there is a gap 26 between the template 25 and the catalyst unit 22 due to manufacturing tolerances. There is a problem in that the exhaust gas G does not pass through the catalyst unit 22 as shown by the arrow in FIG. 9, but flows out into the space 27 where the flow resistance is lowest, resulting in a decrease in denitrification performance.

The present invention aims to eliminate such conventional drawbacks,
The purpose is to provide a denitrification device in which the catalyst block has a sealed structure to prevent untreated exhaust gas from leaking and to improve denitrification performance.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention is solved by arranging a reinforcing plate on the outer peripheral surface of the stacked catalyst blocks to form a sealing structure.

[Made by Kou]

Even when DSS operation or WSS operation is performed, since the outer periphery of the catalyst block is sealed by the reinforcing plate, untreated exhaust gas will not leak, and the denitrification performance will be improved.

〔Example〕

Fig. 1 is a longitudinal sectional view of a denitrification device according to an embodiment of the present invention, Fig. 2 (b) is a detailed enlarged view of the corner part of Fig. 1, and Fig. 3 (aL) is a detailed view of the Figure 1 is an OVa view of the catalyst unit at the ceiling and bottom, Figure 4 is a perspective view of the catalyst block located at the corner, and Figure 5 is a vertical sectional view showing another embodiment of Figure 1. be.

1 to 5, 2 is an exhaust gas passage, 5 is a denitrification device, 22 is a catalyst unit, 23 is a catalyst block, 24
25 is a catalyst block frame, 25 is a V-shaped plate, and 27 is a space, which is the same as the conventional one.

28a, 28b, 28c, and 28d are reinforcing plates arranged on the outer circumference of the stacked catalyst blocks 23; 29 are the catalyst block frame 24 and the reinforcing plates 28. (2) This is a seal welded part where the template 25 and reinforcing plate 28 are seal welded.

In such a structure, in one embodiment of the present invention, as shown in FIG. 1, the outer peripheral surface of the stacked catalyst blocks 23 is covered with a reinforcing plate 28a on the ceiling, a reinforcing plate 28b on the left side, a reinforcing plate 28c on the right side, and a reinforcing plate on the bottom. is covered by the reinforcing plate 28d to form a seal structure.

In other words, the catalyst units 22 of the catalyst blocks 23 located on the ceiling, left side, and right side of the denitrification device 5 are shown in Figure 2 (a).
, as shown in (b), reinforcing plates 28a and 28b.

28c, the catalyst unit 22 located at the ceiling and bottom is supported by the base reinforcing plate 28a shown in FIGS. 3(a) and 3(b).
.

28d and sealed by a seal weld 29.

That is, the catalyst block 23 located on the ceiling in FIG.
As shown in FIG. 2(a), the catalyst unit 22 has a reinforcing plate 28a between the left and right catalyst block frames 24, 24 and the upstream and downstream V-shaped plates 25, 25, as shown in FIG. 2(a). The catalyst block frame 24 and the reinforcing plate 28a are arranged as shown in FIG. 2(a) and FIG. 3(a), and the V-shaped plate 25 and the reinforcing plate 28a are seal-welded by a seal welding portion 29.

On the other hand, the catalyst units 22 of the catalyst blocks 23 located on the left and right sides of FIG. 1 are shown in FIG. 2(a).

As shown in (b), a reinforcing plate 28b is arranged only on the left side of the catalyst unit 22 on the left side, and a reinforcing plate 28c is placed only on the right side of the catalyst unit 22 on the right side, and the catalyst block frame 22 is provided with a reinforcing plate 28c only on the right side.
．． 24 and reinforcing plate 28b, V-shaped plate 25.25 and reinforcing plate 28
b is sealed by a seal weld 29 as shown in FIG. 4, and the reinforcing plate 28c is also seal welded by a seal weld 29 as shown in FIG. 2(b).

On the other hand, the catalyst unit 22 of the catalyst block 23 located at the bottom in FIG.

In this way, as shown by broken lines in FIG. 1, the surfaces of the catalyst block 23 facing the exhaust gas passage 2, that is, the ceiling, the rain side, and the bottom Km strong plates 28a, 28b, 28c.

28d is arranged and sealed by seal welding by the seal welding part 29, so that the untreated exhaust gas G as explained in FIG. Alternatively, the leakage of untreated gas flowing only through the space 27 without passing through the catalyst block 23 can be prevented, and the denitrification performance can also be improved. Even if untreated gas leaks from the right catalyst block 23 to the left catalyst block 23, the outer periphery of the untreated gas is covered by the reinforcing plates 28a, 28b,
28c and 28d, the exhaust gas is denitrated by passing through either catalyst block 23, and is different from the leakage of untreated gas described above.

FIG. 5 shows another embodiment, which differs from the one in FIG. 1 in that reinforcing plates 28b and 28c are provided on both the left and right sides of the catalyst block 23 located at the bottom, and M 1 [
',? Reinforcement plate 28b similar to the one in 1.

28c is sealed by a seal bath contact portion 29.

In this way, the reinforcing plates 28b and 2 are provided on both sides of the catalyst block 230.
By arranging the reinforcing plates 8c, the reinforcing plates 28b and 28c contribute to the rigidity of the catalyst block frame 24, and in plants that require a large amount of catalyst, the catalyst block 23 of the conventional structure
It is possible to support even catalyst blocks 23 in a range that cannot be supported by the strength of the catalyst block frame 24. In this way, reinforcing plates 28b are provided on both sides of the catalyst block 230 located at the bottom.
.

By arranging 28c, it is possible to stack more catalyst blocks 23 upward and downward than before, and a wide range of catalyst filling methods can be selected to deal with pressure loss, layout constraints, etc. This makes it possible and requires less installation space.

As described above, in the embodiment of the present invention, a denitrification device for a combined cycle power plant has been described, but the present invention is not limited to this embodiment, and can be widely applied to a horizontal flow type denitrification device W in which exhaust gas flows horizontally. can.

〔Effect of the invention〕

In the present invention, a reinforcing plate is arranged on the outer circumferential surface of the stacked catalyst blocks to form a sealing structure, which reduces leakage of untreated exhaust gas and improves denitrification performance.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of a denitrification device according to an embodiment of the present invention, Figs. 2(a) and (b) are detailed enlarged views of the corner portions of Fig. 1, and Figs. 3(a) and (b). ) is a side view of the catalyst unit located at the ceiling and bottom of Figure 1, Figure 4 is a perspective view of the catalyst block located at the corner, and Figure 5 is a denitrification example showing another embodiment of Figure 1. Figure 6 shows a schematic system diagram of a combined power generation plant, Figure 7 shows a vertical cross-section of a conventional denitration equipment, Figure 8 shows a perspective view of a conventional catalyst block, and Figure 9 shows a diagram of a conventional catalyst block. FIG. 3 is a side view of the catalyst unit. 2...Exhaust gas passage, 23...Catalyst block, 28a, 28b, 28c,
28 d ---- Reinforcement plate, 29...Seal welded part. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] A denitrification device that denitrates untreated gas in the exhaust gas passage by stacking catalyst blocks in the exhaust gas passage, characterized in that a reinforcing plate is arranged on the outer peripheral surface of the stacked catalyst blocks to form a sealing structure.