JPH0714461B2 - Denitration equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a denitration device for removing nitrogen oxides (NOx) in combustion exhaust gas discharged from a waste heat recovery device of a combined cycle power plant, and particularly to exhaust gas. The present invention relates to an internal heat retention type denitration device in which a horizontal flow occurs.

[Conventional technology]

Large-capacity thermal power plants have been constructed to meet the rapidly increasing demand for electric power, but these boilers are required to perform a transformer operation in order to obtain high power generation efficiency even under partial load.

This is a feature of recent electric power demand, and the difference between the maximum and minimum loads increases along with the growth of nuclear power generation, and thermal power generation tends to shift from base load use to load adjustment use.

In other words, there are few thermal power generation boilers that are always operated at full load, with 75% load, 50% load, and 25% load.
% The load is increased and decreased to operate, the boiler operation is stopped, and so on.
art Stop (hereinafter simply referred to as DSS) or weekend stop (Weekl
y Start Stop (hereinafter simply referred to as WSS) is performed to carry an intermediate load and improve power generation efficiency.

For example, as a part of high-efficiency power generation, a combined power generation plant has recently attracted attention. This combined cycle power generation plant first performs power generation by the gas turbine, and at the same time, recovers heat in the exhaust gas discharged from the gas turbine by a waste heat recovery device (waste heat recovery boiler), which is generated in this waste heat recovery boiler. A steam turbine drives a steam turbine to generate electricity.

This combined cycle power plant has a high power generation efficiency because it uses a gas turbine and a steam turbine to generate power, and the gas turbine has excellent load responsiveness. It also has the advantage of excellent followability and is particularly effective for DSS operation and WSS operation.

However, in this combined cycle power plant, since clean fuels such as LNG and kerosene are used, the SOx amount and the dust amount are reduced, but in the combustion of the gas turbine, since the oxygen amount is large and high temperature combustion is performed, NOx in exhaust gas
As the volume increases, a waste heat recovery boiler with a built-in denitration device has been developed.

FIG. 6 is a schematic system diagram of a combined cycle power generation plant in which an internal heat insulation type denitration device is arranged. In FIG. 6, 1 is a gas turbine, 2 is an exhaust gas passage for introducing exhaust gas G from the gas turbine 1, 3 is a superheater, 4 is a first evaporator, 5 is a denitration device, and 6 is a second evaporator. , 7 are economizers. The superheater 3, the first and second evaporators 4, 6, the denitration device 5, and the economizer 7 are arranged in the exhaust gas passage 2. 8 is a drum for generating steam, 9 is a steam turbine driven by the steam generated in the drum 8, 10 is a condenser for condensing the steam and returning it to water, 11 is water for supplying water from the condenser 10 to the drum 8. A condensate pump, 12 is a water supply line.

The water in the condenser 10 is supplied to the water W by the condensate pump 11, passes through the water supply line 12, is preheated by the exhaust gas G in the economizer 6, and is supplied into the drum 8. The water in the drum 8 descends through the downcomer pipe 13, is introduced into the evaporators 4 and 6 via the pipe lines 14a and 14b, and returns into the drum 8 via the pipe lines 15a and 15b. In this way
While circulating, the steam generated by heat exchange with the exhaust gas G in the evaporators 4 and 6 is introduced into the superheater 3 by the saturated steam pipe 16, where it is superheated by the exhaust gas G, and the main steam pipe 17 serves as superheated steam. Is supplied to the steam turbine 9. 18
Is a turbine bypass pipe that is connected to the main steam pipe and bypasses the steam turbine 9 to directly guide steam to the condenser 10.
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 bypass amount of steam by the supply amount of steam to the steam turbine 9, and 21 is a damper of the exhaust gas duct 2. Is.

The above explanation is an outline of the combined cycle power plant, but in general,
In the exhaust heat recovery boiler, there is arranged a denitration device 5 in which a superheater 3, evaporators 4 and 6 and a economizer 7 are incorporated to recover heat in the exhaust gas and denitrate the exhaust gas.

FIG. 7 is a transverse sectional view of a conventional internal heat retention type denitration apparatus, and FIG. 8 is an enlarged sectional view taken along line VII-VII of a supporting device in which the portion A of FIG. 7 is enlarged. A heat insulating material 23 is lined inside the casing 22 of the exhaust gas passage 2 through which the exhaust gas G passes, and the denitration device 5 is placed on the pedestal 24 inside the heat insulating material 23. As shown in FIG. 9, the denitration device 5 also forms a catalyst block 26 by combining the catalyst unit 25 into several units, and further forms the catalyst block 26.
26 are stacked as shown in FIG. 7 to form the denitration device 5, and the exhaust gas G passes through the denitration device 5 to perform the denitration reaction.

However, as mentioned above, in these combined cycle power plants, since the start and stop are frequently repeated by the DSS operation and WSS operation, the catalyst block 26
Is unilaterally heated by the exhaust gas G from the gas turbine 1, the catalyst block 26 located at the position indicated by the solid line in FIG. 8 extends as indicated by the broken line or the alternate long and short dash line. The so-called stacked catalyst block 26, which returns to the position indicated by the solid line, repeatedly expands and contracts.

As described above, since the conventional denitration device 5 is an internal heat retention type, the catalyst block 26 that receives heat from the gas turbine 1 expands and contracts thermally, but since the casing 22 of the exhaust gas passage 2 is protected by a heat insulating material, the expansion and contraction of heat does not occur. Almost none, the catalyst block 26 cannot be directly fixed to and supported by the casing 22.

Therefore, with respect to vibrations such as earthquakes, a supporting device 28 for supporting the catalyst block 26 from the outside of the casing 22 by using a complex hydraulic vibration isolator 27 having a structure shown in FIG. 8 has been adopted.

The support device 28 comprises a hydraulic vibration isolator 27 and a support rod 29, and the hydraulic vibration isolator 27 is arranged outside the exhaust gas passage 2 in order to prevent the temperature rise due to the exhaust gas G. Therefore, the support rod 29 connecting the support member 20 and the catalyst block 26 has a structure penetrating the casing 22 and the heat insulating material 23 of the exhaust gas passage 2.
Since it moves following the thermal expansion and contraction of the catalyst block 26, the sealing structure and heat insulating structure become complicated as shown in FIG.

[Problems to be solved by the invention]

In this way, in the conventional internal heat retention type denitration device, the catalyst block support structure cannot follow because it starts and repeats the DSS operation and WSS operation, and the stacked catalyst blocks are resistant to vibrations such as earthquakes. It had a very weak support structure.

Further, conventionally, there has been proposed a denitration device as described in JP-A-54-71766. This device forms a cubic catalyst support device with vertical support members on both sides of a catalyst-filled frame. On the other hand, guide frames made of H-shaped steel are erected at predetermined intervals in the reactor body, and the catalyst supporting devices are sequentially inserted between the guide frames to face the catalyst supporting devices of the guide frames. By pressing the tip of the pin provided at the position against the side surface of the catalyst supporting device with the handle, the side end of each catalyst supporting device is brought into close contact with the guide frame.

However, in this denitrification device, the guide frame fixed to the reactor body is integrated with each catalyst support device, so stress is applied to the guide frame every time each catalyst support device repeats thermal expansion and contraction in the vertical and horizontal directions. However, the guide frame and the reactor body to which it is attached are damaged by fatigue.

Further, in order to prevent this from happening, when the pressing force by the pin is loosened, a gap is created between the guide frame and the catalyst supporting device, and unreacted exhaust gas leaks from there, resulting in denitration efficiency. Has the drawback that

The present invention is intended to eliminate such conventional drawbacks,
It is an object of the present invention to provide an internal heat retention type denitration device which can follow the thermal expansion and contraction of a catalyst block and can firmly support vibration such as an earthquake.

[Means for solving problems]

The present invention solves the above-mentioned problems, provides high denitration efficiency even when the exhaust gas temperature is low, and in order to effectively prevent deformation due to heat of the casing, the inside of the casing is lined with a heat insulating material. A catalyst block assembly is arranged in the formed exhaust gas passage to denitrate exhaust gas passing through the exhaust gas passage, wherein a frame-shaped member surrounding the outer periphery of the catalyst block assembly and a beam connecting the frame-shaped member The entire inner surface of the box-shaped support member formed by the members is lined with a plate member, and the box-shaped support member is arranged with a gap between the box-shaped support member and the outer periphery of the catalyst block assembly. The upstream side and the downstream side of the gap between the assembly and the exhaust gas flow direction are sealed by a first seal plate to form a first space portion surrounding the outer periphery of the catalyst block assembly. The box-shaped support member is arranged inside the heat insulating material with a gap, and the gap between the box-shaped support member and the heat insulating material is sealed with a second seal plate to form the first space portion. A second space portion surrounding the outer periphery of the heat insulating material is formed, and the inside of the heat insulating material has a double space portion structure.

[Action]

Thus, according to the present invention, Since the catalyst block assembly is arranged inside the box-shaped support member with a gap therebetween, the thermal expansion and contraction of the catalyst block assembly is not restrained by the box-shaped support member, and the box-shaped support member also has a gap. Since it is arranged inside the heat insulating material, the thermal expansion and contraction of the box-shaped support member can freely expand and contract without being restrained by the heat insulating material, and the box-shaped support member and the heat insulating material are not damaged by expansion and contraction.

． The entire inner surface of the box-shaped support member is lined with a plate member, and the upstream side and the downstream side in the exhaust gas flow direction of the gap between the box-shaped support member and the catalyst block assembly are sealed with the first seal plates, respectively. Therefore, the exhaust gas does not leak between the box-shaped support member and the catalyst block assembly or pass through a part of the catalyst block assembly and leak at another part.

Furthermore, since the gap between the box-shaped support member and the heat insulating material is sealed by the second seal plate, gas leakage does not occur from the gap between the box-shaped support member and the heat insulating material.

Due to this, the exhaust gas always passes through the catalyst block assembly, and high denitration efficiency can be obtained.

． A first space part surrounded by a box-shaped support member, a catalyst block assembly, and a first seal plate, the inside of the heat insulating material;
Due to the double structure of the box-shaped support member, the heat insulating material, and the second space surrounded by the second seal plate, even if the exhaust gas temperature becomes low due to load fluctuation of the boiler, the catalyst block assembly The temperature around the body is maintained at a temperature suitable for the denitration reaction, and high denitration efficiency can be maintained. In particular, the first space portion is a substantially closed chamber-like body, and the catalyst block assembly is surrounded by it, so that the heat retention efficiency is high,
The temperature suitable for the denitration reaction is maintained for a long time.

Further, heat transfer to the casing can be effectively prevented by the double space structure and the heat insulating material, so that deformation of the casing due to heat and heat dissipation to the outside of the device can be effectively prevented.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view according to an embodiment of the present invention, and FIG.
FIG. 3 is a front sectional view of the drawing, FIG. 3 is a lateral sectional view of FIG. 1, FIG. 4 is an enlarged detailed view of a portion B of FIG. 3, and FIG. 5 is a perspective view of a box-shaped support member.

1 to 5, 2 is an exhaust gas passage, 5 is a denitration device, 22 is a casing, 23 is a heat insulating material, 24 is a pedestal, and 26 is a catalyst block, which is the same as the conventional one. For the sake of convenience, 26a is called an upstream catalyst block and 26b is called a downstream catalyst block.

31a, 31b, 31c are frame-shaped members surrounding the outer circumference of the catalyst blocks 26a, 26b, 32a, 32b are beam members connecting the frame-shaped members 31a, 31b, 31c, and 33 are frame-shaped members 31a, 31b, 31c and beam members. 32a, 32b
A box-shaped support member formed by
Upstream and downstream catalyst blocks 26a, 26b arranged inside the
35 is a stopper member, 35 is a thin plate member that is lined inside the box-shaped support member 33 in the exhaust gas flow direction, and 36 is a box-shaped upstream side of the gap 50 between the exhaust gas passage 2 and the box-shaped support member 33 in the exhaust gas flow direction. A second seal plate having a substantially L-shaped cross section that seals the support member 33 so that it can expand and contract, and 37 is a gap 51 between the box-shaped support member 33 and the upstream and downstream catalyst blocks 26a and 26b.
Is a first seal plate for sealing the above, 38 is an additional catalyst block, 39 is an additional catalyst block 38 frame member for an additional catalyst block, and 40 is a beam member for an additional catalyst block.

In such a structure, the frame-shaped members 31a, 31b, 31c are the first
As shown in the figure, the upstream side catalyst block 26a and the downstream side catalyst block 26b are formed in a frame shape surrounding the outer periphery of the frame-shaped member 31a.
Is the upstream catalyst block 26 as shown in FIG. 1 and FIG.
On the upstream side of a, the frame member 31b is arranged between the upstream catalyst block 26a and the downstream catalyst block 26b, and the frame member 31c is arranged on the downstream side of the downstream catalyst block 26b.

Then, the frame-shaped member 31a, the frame-shaped member 31b, and the frame-shaped member 31b
The frame-shaped member 31c and the frame-shaped member 31c are connected by beam members 32a and 32b to form a box-shaped support member 33 as best shown in the perspective view of FIG. As shown in FIGS. 1, 2, and 3, the gun flow side catalyst block 26
a, the downstream side catalyst block 26b is supported in the exhaust gas passage 2.

A thin plate member 35 is lined inside the box-shaped support member 33 in the flow direction of the exhaust gas G as shown in FIGS. 4 and 5, and the frame-shaped members 31a, 31b, 31C and the upstream catalyst block 26 are provided.
A stop member 34 is interposed between the a and the downstream catalyst block 26b.

As described above, in the present invention, as shown in FIGS. 1 to 3, the outer circumferences of the upstream and downstream catalyst blocks 26a and 26b are arranged in the box-shaped support member 33 through the gap 51. Therefore, the thermal expansion and contraction of the catalyst blocks 26a and 26b are not restricted.
Further, since the box-shaped supporting member 33 is arranged in the heat insulating material 23 so as to surround the outer periphery of the box-shaped supporting member 33, the thermal expansion and contraction of the box-shaped supporting member 33 is not restricted. In addition, upstream and downstream catalyst blocks
Since 26a, 26b are integrated by the box-shaped support member 33 via the stopper member 34, there is no fall of each catalyst block 26a, 26b, and only the bottom of the denitration device 5 does the catalyst block 26a, 26b.
Supporting the entire 6b eliminates the problem of strength.

Further, a thin plate member 35 is lined around the inner surface of the box-shaped support member 33, and, as shown in FIG. 3, is sealed by the first seal plate 37 on the upstream and downstream sides of the gap 51 in the exhaust gas flow direction. Therefore, the exhaust gas does not leak between the box-shaped support member 33 and the catalyst blocks 26a, 26b, and does not leak, for example, through the upstream catalyst block 26a and the downstream catalyst block 26b, and this space There is almost no movement of air in.

At the gap 51, the box-shaped support member 33 and the catalyst block 26.
A substantially closed chamber-shaped first space surrounded by a and 26b and the front and rear first seal plates 37 is formed. Also, the gap
At 50, a second space portion surrounded by the box-shaped support member 33, the heat insulating material 23 and the second seal plate 36 is formed. The outer periphery of the first space portion is covered with the second space portion, and the second space portion is further covered with the heat insulating material 23, so that the inner side of the heat insulating material 23 and the first space portion are It has a double space part structure with two space parts.

Therefore, even if the exhaust gas temperature becomes low due to a change in the load of the boiler, the temperature of the catalyst blocks 26a and 26b is maintained at a temperature suitable for the denitration reaction, and high denitration efficiency can be maintained.

Further, heat transfer to the casing 22 can be effectively prevented by the double space structure and the heat insulating material 23, and deformation of the casing 22 made of a thin plate due to heat and heat dissipation to the outside of the device can be effectively prevented.

Further, by supporting the denitration device 5 by the box-shaped support member 33, the entire denitration device 5 can be blocked and transported to the construction site at the factory, and the block construction method can be used for short-time construction. .

The additional catalyst block 38 in FIGS. 1 and 3 is the gun flow side catalyst block 26a and the downstream side catalyst block 26b.
This is used when the same catalyst is deteriorated and the same denitration efficiency is obtained by further stacking the catalyst block 38 on the downstream side of the downstream side catalyst block 26b as shown by the broken lines in FIGS. 1 and 3.

In this way, if the frame-shaped member 39 and the beam member 40 for the catalyst block that are added downstream of the frame-shaped member 31c are integrated with the box-shaped support member 33, the added catalyst block 38 can be quickly added, and the like. Upstream and downstream of the catalyst block 26a, 26b
Can be supported as well.

Although the denitration apparatus of the combined cycle power plant has been described in the embodiments of the present invention, the present invention is not limited to the denitration apparatus of the combined cycle power plant, and to a denitration apparatus such as a thermal power generation boiler or another combustion furnace. Can also be applied.

〔The invention's effect〕

According to the present invention, since the catalyst block is arranged inside the box-shaped support member with a gap therebetween, thermal expansion and contraction of the catalyst block is not restrained by the box-shaped support member, and the box-shaped support member does not have the gap. Since it is placed inside the heat insulating article, the thermal expansion and contraction of the box-shaped support member can be freely expanded and contracted without being restrained by the heat insulation material, so that the box-shaped support member and the heat insulation material are not damaged by expansion and contraction. .

Further, since the entire inner surface of the box-shaped support member is lined with a plate member and the gap between the box-shaped support member and the outer periphery of the catalyst block is sealed by the first seal plate, the box-shaped support member and the catalyst block are sealed. It is possible to prevent gas leakage between the space and the box-shaped support member. Further, since the upstream side of the gap between the box-shaped support member and the heat insulating material in the exhaust gas flow direction is sealed by the second seal plate, gas leakage from the gap between the box-shaped support member and the heat insulating material can be prevented, and high denitration efficiency can be maintained. .

Furthermore, in response to vibration such as an earthquake, the catalyst block sways only between the box-shaped support member and the heat-insulating material, and the box-shaped support member sways only between the heat-insulating material and the vibration. Absent.

[Brief description of drawings]

1 to 5 show a denitration apparatus according to an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of the denitration apparatus, and FIG.
Front sectional view of the figure, FIG. 3 is a transverse sectional view, FIG. 4 is an enlarged detailed view of portion B of FIG. 3, FIG. 5 is a perspective view of a box-shaped support member, and FIG. FIG. 7 is a schematic sectional view of a conventional denitration apparatus, FIG. 8 is an enlarged detailed view of a portion A of FIG. 7, and FIG. 9 is a perspective view of a catalyst block. 2 ... Exhaust gas passage, 20 ... Casing, 23 ... Heat insulation material,
26a, 26b, 38 ... Catalyst block, 31a, 311b, 31c, 39 ...
... Frame member, 32a, 32b, 40 ... Beam member, 33 ... Box-shaped support member, 35 ... Thin plate member, 36 ... Second seal plate,
37 …… First seal plate, 50,51 …… Gap.

Claims (1)

[Claims] 1. An assembly of catalyst blocks is arranged in an exhaust gas passage formed by lining the inside of a casing with a heat insulating material,
In denitrifying the exhaust gas passing through the exhaust gas passage, a frame-shaped member surrounding the outer periphery of the catalyst block assembly and a box-shaped support member formed by beam members connecting the frame-shaped members are entirely plate-shaped on the inner surface. It is lined, and the box-shaped supporting member is arranged with a gap between the box-shaped supporting member and the outer periphery of the catalyst block assembly, and the gap between the box-shaped supporting member and the catalyst block assembly is upstream and downstream in the exhaust gas flow direction. Each side is sealed with a first seal plate to form a first space surrounding the outer periphery of the catalyst block assembly, and the box-shaped support member is arranged inside the heat insulating material with a gap, A gap between the box-shaped support member and the heat insulating material is sealed with a second seal plate to form a second space portion that surrounds the outer periphery of the first space portion, and the inside of the heat insulating material is divided into two parts. It is characterized by having a heavy space structure Denitration equipment.