JP6785046B2 - How to remove exhaust ducts, boilers and solid particles - Google Patents

Description

The present invention relates to an exhaust duct provided in a boiler for generating steam, a boiler provided with this exhaust duct, and a method for removing solid particles in exhaust gas flowing through the exhaust duct.

A large boiler such as a conventional coal-fired boiler has a hollow-shaped fireplace installed in the vertical direction, and a plurality of combustion burners are arranged along the circumferential direction on the fireplace wall. In the coal-fired boiler, a flue is connected above the fireplace in the vertical direction, and a heat exchanger that generates steam inside is arranged in this flue. Therefore, the combustion burner injects a mixture of fuel and air into the fireplace to form a flame, and the flame generates combustion gas and flows through the flue. Then, steam is generated by heating the boiler supply water flowing through the heat exchanger with the combustion gas generated by combustion, and the generated steam is supplied to drive the steam turbine to rotate, and a generator connected to the rotating shaft of the steam turbine. Can be driven to generate electricity. In addition, an exhaust gas passage is connected to this flue, and the exhaust gas passage is provided with a denitration device, an electrostatic precipitator, a desulfurization device, etc. for purifying combustion gas, and a chimney is provided at the downstream end. ..

In such a coal-fired boiler, the denitration device arranged in the exhaust duct supplies a reducing agent such as ammonia to the flue, and the exhaust gas to which the reducing agent is supplied promotes the reaction between the nitrogen oxide and the reducing agent. Nitrogen oxides in the exhaust gas are reduced and removed by passing through the catalyst. Therefore, a reducing agent supply device is provided in the flue on the upstream side of the exhaust gas from the catalyst (denitration catalyst) arranged in the denitration device. As such a boiler, for example, there is one described in Patent Document 1 below.

Japanese Unexamined Patent Publication No. 08-089754 JP-A-2015-124913

By the way, in a coal-fired boiler, since pulverized coal as fuel is burned in a fireplace, solid particles such as coal ash (clinker and the like) are mixed in the exhaust gas. Since these solid particles are lumps of ash and flow through the exhaust duct together with the flow of exhaust gas, they may flow into the denitration catalyst of the denitration device provided in the middle of the exhaust duct. As the denitration catalyst, a catalyst such as vanadium is supported on a honeycomb-shaped or plate-shaped base material, but solid particles may be deposited on the denitration catalyst. When solid particles are deposited on the denitration catalyst, the contact area between the catalyst and the exhaust gas may be reduced, which may cause a decrease in denitration performance. Further, when the exhaust gas flow path on the catalyst is narrowed, the pressure loss increases and the power of the exhaust gas blower increases, which may lead to a decrease in performance. As a technique for collecting solid particles in exhaust gas, for example, there is one described in Patent Document 2 above. In Patent Document 2, a hopper capable of recovering solid particles in exhaust gas is provided in the flue, and a baffle plate for preventing the outflow of solid particles from the hopper is provided. However, in Patent Document 2, since it is difficult to collect the solid particles suspended in the exhaust gas, the solid particles suspended in the exhaust gas flow into the denitration catalyst of the denitration device arranged on the downstream side. It cannot be suppressed sufficiently.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide an exhaust duct and a boiler for collecting solid particles suspended in exhaust gas, and a method for removing solid particles.

The exhaust duct of the present invention for achieving the above object has an exhaust gas passage through which exhaust gas containing solid particles generated by combustion of fuel flows, and a reducing agent supply unit that supplies a reducing agent to the exhaust gas in the exhaust gas passage. A denitration catalyst provided on the downstream side of the exhaust gas flow direction from the exhaust gas supply device in the exhaust gas passage to promote the reaction between the reducing agent and the nitrogen oxide in the exhaust gas, and the above. A protective member provided on the upstream side in the exhaust gas flow direction from the reducing agent supply unit to block the collision of the exhaust gas with the reducing agent supply unit, and a protective member provided on the upstream side in the exhaust gas flow direction from the protective member. It is characterized by including a low repulsion portion having a smaller repulsion coefficient with the solid particles than the member.

Therefore, when the exhaust gas flows through the exhaust gas passage, when the reducing agent supply unit of the reducing agent supply device supplies the reducing agent to the exhaust gas passage, the denitration catalyst promotes the reaction between the reducing agent and the nitrogen oxide in the exhaust gas. Reduce nitrogen oxides. At this time, a protective member is already provided on the upstream side of the reducing agent supply unit to prevent solid particles contained in the exhaust gas from colliding with the reducing agent supply unit, and the reducing agent supply unit due to the collision of the solid particles is suppressed. Although wear is reduced, since a low repulsion portion is provided on the upstream side of this protective member, some of the solid particles contained in the exhaust gas collide with the low repulsion portion, but they are easily elastically deformed and have a coefficient of restitution. In the low-repulsion portion where the size is small, the amount of repulsion of the solid particles is small, so the solid particles fall due to their own weight without repulsion. Therefore, when collecting the solid particles suspended in the exhaust gas, the pressure loss of the exhaust gas flowing through the exhaust gas does not increase, and the solid particles can be easily collected by the low repulsion portion provided in the protective member. Since the solid particles collide with the low-resilience portion and fall to the lower part of the exhaust gas passage without repulsion, it is possible to suppress the re-mixing of the collected solid particles into the exhaust gas, and as a result, the solid particles in the denitration catalyst. Accumulation can be reduced. In addition, since the low-resilience portion is provided on the upstream side of the protective member, wear due to collision of solid particles of the protective member itself can be suppressed by a synergistic effect with the low-resilience portion, and the life of the protective member can be extended. It will be possible.

In the exhaust duct of the present invention, the reducing agent supply unit includes a plurality of reducing agent injection nozzles for injecting the reducing agent into the exhaust gas, and a split reducing agent injection pipe for supplying the reducing agent to the plurality of reducing agent injection nozzles. The plurality of reducing agent injection nozzles are arranged on the outer surface of the split reducing agent injection pipe toward the downstream side in the flow direction of the exhaust gas, and the protective member includes the split reducing agent injection pipe and the plurality of reducing agents. The low repulsion portion is arranged on the upstream side in the flow direction of the exhaust gas in the injection nozzle, and the low repulsion portion is at least upstream in the flow direction of the exhaust gas in the split reducing agent injection pipe of the protective member arranged on the most upstream side in the flow direction of the exhaust gas. It is characterized by being placed on the side.

Therefore, by arranging the protective member on the upstream side in the flow direction of the exhaust gas in the split reducing agent injection pipe and each reducing agent injection nozzle, collision of solid particles with the reducing agent injection pipe and each reducing agent injection nozzle is suppressed and wear is performed. By arranging the low repulsion part on the upstream side in the flow direction of the exhaust gas in the split reducing agent injection pipe arranged on the most upstream side, the solid particles collide with the low repulsion part and fall. By doing so, the solid particles suspended in the exhaust gas can be reduced.

In the exhaust duct of the present invention, the split reducing agent injection pipe and the protective member are arranged so as to be offset in the horizontal direction intersecting the flow direction of the exhaust gas, and the low repulsion portion is arranged on the upstream side of the protective member. It is characterized by that.

Therefore, since the blockage ratio by the protective member is not increased, the pressure loss of the exhaust gas flow is not increased, and a large amount of exhaust gas can collide with the low repulsion portion to drop the solid particles, so that the solid particles can be collected more easily. can do.

The exhaust duct of the present invention is characterized in that the low-resilience portion is formed of a first perforated plate.

Therefore, by setting the low-resilience portion as the first perforated plate arranged on the upstream side of the protective member, the protective member and the first perforated plate as the low-resilience portion are separate members. Therefore, it is possible to firmly manufacture a protective member that collides solid particles to prevent wear of the reducing agent supply portion, while reducing the amount of repulsion of the low repulsion portion that collides with the solid particles and drops them. It can be manufactured according to the function.

The exhaust duct of the present invention is characterized in that the first perforated plate is made of a wire mesh member.

Therefore, by using the first perforated plate constituting the low-resilience portion as a wire mesh member, the low-resilience portion can be easily manufactured with a simple configuration and at low cost, and the wire mesh member can easily be solid. It can absorb the collision force of particles and drop them.

The exhaust duct of the present invention is characterized in that a gap is provided between the first perforated plate and the protective member.

Therefore, by providing a gap between the first perforated plate constituting the low-resilience portion and the protective member, even the solid particles A through which the low-resilience net 62 has passed through the gap repels the surface of the protector 61 and the low-resilience net 62 Since it collides with and falls, it can be easily collected. In addition, a pressure loss of the exhaust gas that has passed through the first perforated plate is generated, and a region where the flow of the exhaust gas in the gap is remarkably slowed down is created, so that the solid particles that collide with the first perforated plate and fall are suppressed from being remixed into the exhaust gas. Therefore, the solid particles that collide with the first perforated plate can be effectively dropped.

In the exhaust duct of the present invention, the exhaust gas passage is connected to a horizontal portion of the exhaust gas passage through which the exhaust gas flows in the horizontal direction and a downstream side in the horizontal portion in the flow direction of the exhaust gas, and the exhaust gas flows in the vertical direction. A vertical portion of the exhaust gas passage is provided, the reducing agent supply portion is arranged in the horizontal portion, and a hopper for collecting the solid particles is provided at a connecting portion between the horizontal portion and the vertical portion to supply the reducing agent. It is characterized in that a soaring prevention member is arranged by providing a predetermined gap between the portion and the hopper and the bottom surface of the horizontal portion.

Therefore, by arranging a soaring prevention member between the reducing agent supply unit and the hopper, some of the solid particles contained in the exhaust gas collide with the low repulsion portion, and the collision force is absorbed by this low repulsion portion. Although it falls, the fallen solid particles flow through the flow path between the prevention member and the bottom surface of the horizontal part due to the flow of exhaust gas and enter the hopper, and the solid particles dropped at the low repulsion part flow through the exhaust gas. It can be guided to the hopper and stored in the hopper without being remixed by the exhaust gas flowing in the road, and the solid particles floating in the exhaust gas can be easily collected.

The exhaust duct of the present invention is characterized in that the soaring prevention member is composed of a second perforated plate.

Therefore, by using the second perforated plate as the soaring prevention member, the solid particles that have fallen on the upper surface of the second perforated plate fall from a large number of holes to the bottom surface of the horizontal portion, and are not remixed into the exhaust gas due to the soaring. The fluid force of the exhaust gas flowing near the bottom surface of the exhaust duct causes the exhaust gas to enter the hopper, and it is possible to suppress the accumulation of solid particles on the upper surface portion of the soaring prevention member.

Further, the boiler of the present invention includes a fireplace having a hollow shape and installed along the vertical direction, a combustion device arranged in the fireplace, and an exhaust duct connected to an upper portion in the vertical direction in the fireplace. It is characterized by having.

Therefore, a flame is formed by blowing fuel into the fireplace by the combustion device, and the generated combustion gas flows into the exhaust duct. At this time, some of the solid particles contained in the exhaust gas collide with the low-repulsion portion and fall due to their own weight without significant repulsion. Therefore, by easily collecting the solid particles suspended in the exhaust gas by the low repulsion portion, the accumulation of the solid particles on the denitration catalyst can be reduced, and as a result, the purification performance of the exhaust gas by the denitration catalyst is maintained. In addition to being able to improve durability, it is also possible to suppress an increase in pressure loss in the exhaust duct and suppress an increase in power for discharging exhaust gas such as an exhaust blower.

Further, the method for removing solid particles of the present invention is a method for removing solid particles contained in exhaust gas flowing through an exhaust gas passage, in which the solid particles are arranged on the upstream side in the flow direction of exhaust gas from a protective member provided in a reducing agent supply unit. The solid particles that collide with the low-repulsion portion and drop, and then collide with the low-repulsion portion and fall are between the bottom surface of the exhaust gas passage and the soaring prevention member installed with a gap due to the flow of exhaust gas. The solid particles are collected by a hopper provided on the downstream side of the exhaust gas flow of the low repulsion portion.

Therefore, some of the solid particles contained in the exhaust gas collide with the low-resilience portion and fall due to their own weight without significant repulsion, so that the solid particles suspended in the exhaust gas can be easily collected by the low-resilience portion. At the same time, it is possible to suppress the re-mixing of the collected solid particles into the exhaust gas, and as a result, the accumulation of the solid particles on the denitration catalyst can be reduced.

According to the exhaust duct, the boiler, and the method for removing solid particles of the present invention, a low-repulsion portion having a smaller coefficient of restitution than the protective member is provided on the upstream side surface of the protective member provided on the upstream side in order to suppress wear of the reducing agent supply portion. Since it is provided, the pressure loss of the exhaust gas flowing through the exhaust duct does not increase as compared with the structure of the conventional exhaust duct, and the solid particles suspended in the exhaust gas can be easily collected by the low repulsion portion.

FIG. 1 is a schematic configuration diagram showing a coal-fired boiler of the first embodiment. FIG. 2 is a schematic side view showing the exhaust duct of the first embodiment. FIG. 3 is a sectional view taken along line III-III of FIG. 2 showing an exhaust duct. FIG. 4 is a front view showing the reducing agent supply device. FIG. 5 is a VV cross-sectional view of FIG. 4 showing a reducing agent supply device. FIG. 6 is a sectional view taken along line VI-VI of FIG. 4 showing a reducing agent supply device. FIG. 7 is a schematic side view showing the exhaust duct of the second embodiment.

Hereinafter, preferred embodiments of the exhaust duct and boiler and the method for removing solid particles according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to this embodiment, and when there are a plurality of embodiments, the present invention also includes a combination of the respective embodiments.

[First Embodiment]
FIG. 1 is a schematic configuration diagram showing a coal-fired boiler of the first embodiment.

The boiler of the first embodiment uses pulverized coal obtained by crushing coal as pulverized fuel (solid fuel) to burn solid fuel, burns the pulverized coal with a combustion burner, and recovers the heat generated by this combustion. It is a pulverized coal-fired boiler that can be used.

In the first embodiment, as shown in FIG. 1, the coal-fired boiler 10 is, for example, a conventional boiler, which includes a fireplace 11, a combustion device 12, and a flue 13. The fireplace 11 has a hollow shape of a square cylinder and is installed along the vertical direction. The fireplace wall constituting the fireplace 11 is composed of a heat transfer tube, and heat exchange with water supply suppresses the temperature rise of the fireplace wall. ing. The upper, upper and upper parts represent the upper side in the vertical direction, and the lower, lower and lower parts represent the lower side in the vertical direction.

The combustion device 12 is provided on the vertically lower side of the furnace wall (heat transfer tube) constituting the fireplace 11. The combustion device 12 has a plurality of combustion burners 21, 22, 23, 24, 25 mounted on the furnace wall. In the present embodiment, for example, the combustion burners 21, 22, 23, 24, 25 are arranged along the circumferential direction of the fireplace 11 at equal intervals of four as a set, along the vertical direction. Five sets, that is, five stages are arranged. However, the shape of the fireplace, the number of combustion burners in one stage, and the number of stages are not limited to this embodiment.

Each of the combustion burners 21, 22, 23, 24, 25 is connected to the pulverizer (pulverized coal machine / mill) 31, 32, 33, 34, 35 via the pulverized coal supply pipes 26, 27, 28, 29, 30. It is connected. Therefore, when coal is transported by a transport system (not shown) and charged into the crushers 31, 32, 33, 34, 35, it is crushed to a predetermined size here and pulverized coal by the transport air (primary air). The crushed coal (pulverized coal) can be supplied to the combustion burners 21, 22, 23, 24, 25 from the supply pipes 26, 27, 28, 29, 30.

The flue 13 is connected to the upper part of the fireplace 11. The flue 13 serves as a heat exchanger for recovering the heat of the combustion gas, such as a superheater (super heater) 41, 42, 43, a reheater (reheater) 44, 45, and a coal saver (economizer) 46, 47 is provided, and heat exchange is performed between the combustion gas generated by the combustion in the fireplace 11 and the water supply together with the heat transfer tube of the fireplace wall constituting the fireplace 11.

A gas duct 48 for discharging the heat-exchanged combustion gas is connected to the flue 13 on the downstream side thereof. An air heater 49 is provided between the gas duct 48 and the air duct 37, and heat exchange is performed between the air flowing through the air duct 37 and the exhaust gas flowing through the gas duct 48, and the combustion burners 21, 22, 23, 24, The temperature of the combustion air supplied to 25 can be raised.

Further, the flue 13 is provided with a selective reduction catalyst (denitration catalyst) 50 at a position upstream of the air heater 49 in the flow direction of the exhaust gas. The selective reduction catalyst 50 promotes the reaction between the nitrogen oxides present in the exhaust gas supplied with the reducing agent having the action of reducing the nitrogen oxides and the reducing agent, and removes the nitrogen oxides in the exhaust gas. It is effective for removing and reducing by decomposing into nitrogen and water. Therefore, the flue 13 is provided with a reducing agent supply device 51 that supplies the reducing agent into the flue 13 on the upstream side in the flow direction of the exhaust gas from the selective reduction catalyst 50. The reducing agent supply device 51 supplies the reducing agent to the entire surface of the flow path in the flue 13 toward the downstream side and ejects the reducing agent into the exhaust gas, thereby diffusing the reducing agent over the entire exhaust gas flowing in the flow path. Can be mixed. As the reducing agent, aqueous ammonia, gaseous ammonia, urea water or the like can be used. The gas duct 48 connected to the flue 13 is provided with a dust treatment device (electrostatic precipitator, desulfurization device) 52 and an attractive blower 53 at a position downstream of the air heater 49, and a chimney 54 is provided at the downstream end. The exhaust gas recovers thermal energy, is purified, and is discharged into the atmosphere.

The pulverized coal generated by driving the crushers 31, 32, 33, 34, 35 passes through the pulverized coal supply pipes 26, 27, 28, 29, 30 together with the transport air, and the combustion burners 21, 22, 23, 24, 25. Is supplied to. Further, the combustion air is heated by the air heater 49 by the blower 38 and supplied from the air duct 37 to the combustion burners 21, 22, 23, 24, 25 via the air box 36. Then, the combustion burners 21, 22, 23, 24, 25 blow the pulverized fuel mixture in which the pulverized coal and the transport air are mixed into the furnace 11 and the combustion air into the furnace 11, and at this time, the pulverized fuel is mixed. A flame is formed by igniting air or combustion air. In this fireplace 11, the pulverized fuel mixture and the combustion air burn to generate a flame, and when a flame is generated on the vertically lower side in the fireplace 11, the combustion gas rises in the fireplace 11 and the flue 13 Is discharged to.

The combustion gas discharged to the flue 13 is heat-exchanged with water supply and steam by the superheaters 41, 42, 43, the reheaters 44, 45, and the economizers 46, 47 arranged in the flue 13, and is exhaust gas. It becomes. The generated steam can be supplied to a steam turbine (not shown) to rotationally drive the steam turbine, and a generator (not shown) connected to the rotating shaft of the steam turbine can be rotationally driven to generate power.
The reducing agent supply device 51 ejects and supplies the reducing agent to the exhaust gas after heat exchange and diffuses the reducing agent, and the selective reduction catalyst 50 is a nitrogen oxide and the reducing agent in the exhaust gas to which the reducing agent is supplied. The reaction is promoted, and nitrogen oxides in the exhaust gas are reduced and removed by decomposing them into nitrogen and water. After that, the exhaust gas is discharged from the chimney 54 into the atmosphere after the particulate matter is removed by the dust treatment device 52 and the sulfur content is removed and purified.

In the coal-fired boiler 10 configured in this way, in the present embodiment, the downstream side (flue 13 side) from the fireplace 11 functions as the exhaust duct of the first embodiment. The flue 13 includes a first horizontal flue portion 13a, a first vertical flue portion 13b, a second horizontal flue portion 13c, a second vertical flue portion 13d, a third horizontal flue portion 13e, and a third. The vertical flue portion 13f is continuously provided and configured, and the gas duct 48 is connected to the third vertical flue portion 13f.

Then, for example, in the flue 13, superheaters 41, 42, reheaters 43, 44, and economizers 45, 46, 47 are arranged in the first horizontal flue portion 13a and the first vertical flue portion 13b. You may be. Further, in the present embodiment, in the flue 13, the first hopper 55 is installed at the lower end of the first vertical flue portion 13b through which the exhaust gas having an upward velocity component flows, and the exhaust gas having an upward velocity component flows. 2 A second hopper 56 is installed at the lower end of the vertical flue portion 13d. Further, in the flue 13, the reducing agent supply device 51 is arranged in the second horizontal flue portion 13c through which the exhaust gas flows horizontally, and the selective reduction catalyst 50 is arranged in the third vertical flue portion 13f in which the exhaust gas flows downward. ing.

Hereinafter, the exhaust duct of the first embodiment will be described. FIG. 2 is a schematic side view showing the exhaust duct of the first embodiment, FIG. 3 is a sectional view taken along line III-III of FIG. 2 showing the exhaust duct, FIG. 4 is a front view showing the reducing agent supply device, and FIG. , VV cross-sectional view of FIG. 4 showing the reducing agent supply device, FIG. 6 is a VI-VI cross-sectional view of FIG. 4 showing the reducing agent supply device.

As shown in FIGS. 2 and 3, the exhaust duct of the first embodiment includes a flue (exhaust gas passage) 13, a selective reduction catalyst 50 (see FIG. 1), a reducing agent supply device 51, and a protector (protection). A member) 61 and a low-resilience net (low-resilience portion) 62 are provided.

Since pulverized coal as fuel is burned in the furnace 11, solid particles (clinker or the like) A such as coal ash are mixed in the exhaust gas G, float in the exhaust gas G, and flow to the downstream side together with the exhaust gas G. The solid particles A are so-called ash lumps, which cause wear of the structure, deteriorate the purification performance of the exhaust gas when deposited on the selective reduction catalyst 50, and increase the pressure loss. Become. In the flue 13, when the solid particles A collide with a structure or the like, they repel and float in the exhaust gas G again. In addition, some solid particles A lose their moving force due to collision and fall due to gravity.

The first hopper 55 mainly collects and stores the large-diameter solid particles A contained in the exhaust gas G. The first hopper 55 is provided on the downstream side in the flow direction of the exhaust gas G in the first vertical flue portion 13b, and is provided at the bottom of the upstream side in the flow direction of the exhaust gas G in the second horizontal flue portion 13c. The solid particles A that fall due to the change in the flow path direction of the exhaust gas G are collected. The first hopper 55 has a concave shape such that the bottom portion of the second horizontal flue portion 13c has a substantially inverted triangular cross section vertically downward, and is provided along the width direction of the second horizontal flue portion 13c. There is.

The second hopper 56 mainly collects and stores the small-diameter solid particles A contained in the exhaust gas G. The second hopper 56 is provided on the upstream side of the second vertical flue portion 13d in the flow direction of the exhaust gas, and is provided at the bottom of the second horizontal flue portion 13c on the downstream side of the flow direction of the exhaust gas G. The second hopper 56 has a concave shape such that the bottom portion of the second horizontal flue portion 13c has a substantially inverted triangular cross section downward vertically, and is provided along the width direction of the second horizontal flue portion 13c. There is.

The reducing agent supply device 51 is provided in the second horizontal flue portion 13c as shown in FIGS. 1 to 3. The second horizontal flue portion 13c has a rectangular cross section, and is composed of a ceiling portion 71a, a bottom portion 71b, and side wall portions 71c, 71d. The reducing agent supply device 51 includes a reducing agent supply unit 72, a reducing agent supply pipe 73, a reducing agent supply source 74, and an on-off valve 75. The reducing agent supply unit 72 is arranged inside the second horizontal flue unit 13c, and is composed of a reducing agent injection pipe 81 and a plurality of reducing agent injection nozzles 82.

A plurality of reducing agent injection pipes 81 are arranged along the vertical direction at the second horizontal flue portion 13c and at predetermined intervals in the horizontal direction. The upper end portion is supported by the ceiling portion 71a, and the lower end portion is the bottom portion 71b. Is supported by. The plurality of reducing agent injection nozzles 82 extend from the plurality of reducing agent injection pipes 81 toward the downstream side in the flow direction of the exhaust gas G, and are provided at predetermined intervals in the longitudinal direction of each reducing agent injection pipe 81. Has been done.

Specifically, as shown in FIGS. 4 to 6, the reducing agent injection pipe 81 is a pipe having a cylindrical shape, and the plurality of reducing agent injection nozzles 82 are located in the longitudinal direction of the reducing agent injection pipe 81. It is fixed at predetermined intervals (preferably even intervals). In this case, the plurality of reducing agent injection nozzles 82 are alternately fixed at a predetermined angle in the horizontal direction with respect to the flow direction of the exhaust gas G. That is, the reducing agent injection nozzle 82 at the uppermost portion faces one side in the width direction of the second horizontal flue portion 13c, and the reducing agent injection nozzle 82 at the second stage has the width of the second horizontal flue portion 13c. The reducing agent injection nozzle 82 in the third stage is arranged so as to face the other side in the direction and face one side in the width direction of the second horizontal flue portion 13c. The horizontal angle formed by each reducing agent injection nozzle 82 may be appropriately set according to the number and spacing of the reducing agent injection pipes 81.

Then, as shown in FIGS. 2 and 3, in the plurality of reducing agent injection pipes 81, the reducing agent supply source 74 is connected to the upper end portion via the reducing agent supply pipe 73, and an on-off valve (on-off valve () is connected to the reducing agent supply pipe 73. Alternatively, a flow rate adjusting valve) 75 is provided.

The protector 61 constituting the protective member is provided on the upstream side in the flow direction of the exhaust gas G from the reducing agent supply unit 72. The protector 61 is, for example, a metal plate material (for example, a carbon steel plate), and is provided along the vertical direction at the second horizontal flue portion 13c and at predetermined intervals in the width direction of the second horizontal flue portion 13c. A plurality of them are arranged, and the upper end portion extends to the ceiling portion 71a and the lower end portion extends to the bottom portion 71b. As shown in FIGS. 4 to 6, in the protector 61, the flat surface portion on one side (downstream side in the flow direction of the exhaust gas G) is in close contact with the reducing agent injection pipe 81, and the reducing agent injection pipe 81 is provided by the pair of support members 83. It is fixed to. Therefore, when viewed from the upstream side of the exhaust gas G in the second horizontal flue portion 13c, as shown in FIG. 3, the reducing agent injection pipe 81 and the plurality of reducing agent injection nozzles 82 are arranged to be hidden by the protector 61. .. The protector 61 can suppress the collision of the solid particles A in the exhaust gas G with the reducing agent injection pipe 81 and each reducing agent injection nozzle 82 to reduce wear.

The low-resilience portion is a first perforated plate, and in the present embodiment, it is composed of a low-resilience net 62 as a wire mesh member. Since the low repulsion net 62 is easily elastically deformed, it can efficiently absorb the collision energy of the solid particles A and reduce the amount of repulsion. It has a smaller coefficient of restitution than the protector 61, and this protector. It is provided on the upstream side in the flow direction of the exhaust gas G from 61. As shown in FIG. 3, a plurality of low-resilience nets 62 are arranged together with the protector 61 along the vertical direction at the second horizontal flue portion 13c and at predetermined intervals in the width direction of the second horizontal flue portion 13c. The upper end extends to the ceiling 71a, and the lower end extends to the bottom 71b. As shown in FIGS. 4 to 6, in the low-resilience net 62, the flat surface portion on one side (downstream side in the exhaust gas flow direction) is the flat surface portion on the other side (upstream side in the exhaust gas flow direction) of the protector 61. It is fixed to the protector 61 facing the protector 61. Therefore, when viewed from the upstream side of the exhaust gas G in the second horizontal flue portion 13c, the protector 61 is arranged to be hidden by the low repulsion net 62.

That is, the low-resilience net 62 is set to have substantially the same size as the protector 61. However, the present invention is not limited to this configuration, and the low-resilience net 62 may be made smaller or larger than the protector 61, or may be divided into a plurality of parts and fixed at a specific position on the protector 61. Good. Further, a plurality of set low-resilience nets 62 may be stacked and fixed to the protector 61.

Further, in the present embodiment, the low repulsion portion is a low repulsion net 62 as the first perforated plate, and the restitution coefficient is about half or less than the restitution coefficient of the protector 61, but the configuration is not limited to this. Absent. As the low-resilience portion, for example, a grating, a perforated plate, a net, a bamboo blind structure (shutter), or the like can be used in addition to the low-resilience net 62. In the case of a low-resilience portion having a large number of openings, a grid-like structure having a large number of openings having a size that the solid particles A having a particle size to be collected cannot easily pass through is more preferable, but the passed solid particles A are the protector. If the amount of repulsion can be reduced by the interaction with 61, the size of the opening does not matter. In particular, when a lattice-shaped low-resilience member made of a material that elastically deforms in response to the collision of the solid particles A, such as the low-resilience net 62, is adopted, the collision energy of the solid particles A is efficiently absorbed by the elastic deformation and the amount of repulsion is increased. Can be reduced. Further, the amount of repulsion can be reduced by rotating the solid particles A that collide with each other. In addition, as the low-resilience part, a heat insulating material, a rubber-based material, a mat, a plastic material, or the like that can withstand the usage environment (temperature, exhaust gas component, etc.) can be adopted. Further, the low-resilience portion may be formed by providing an uneven shape on the surface of a metal plate material, or may form an uneven shape directly on the surface of the protector 61 on the upstream side in the flow direction of the exhaust gas G.

In this case, the protector 61 and the low-resilience net 62 may be fixed in close contact with each other, or may be fixed with a gap. When the protector 61 and the low-resilience net 62 are closely fixed to each other, the work of attaching the low-resilience net 62 to the protector 61 becomes easy. On the other hand, when the protector 61 and the low-resilience net 62 are fixed with a gap, the solid particles A that the low-resilience net 62 has passed through the gap repel the surface of the protector 61 and face the protector 61 of the low-resilience net 62. Since it collides with the side of the net and the amount of repulsion decreases and it falls, it can be easily collected. Further, paying attention to the local portion that collides with the low repulsion network 62, the exhaust gas G passes through the low repulsion network 62 and collides with the surface of the protector 61 to generate a turbulent flow, which causes a pressure loss in the flow of the exhaust gas G. Since a region where the flow of the exhaust gas G becomes low is generated, the remixing of the solid particles A that collide with the low repulsion network 62 and fall into the exhaust gas G is suppressed.

Here, in the second horizontal flue portion 13c, the protector 61 is arranged on the upstream side in the flow direction of the exhaust gas G from the reducing agent supply portion 72, and the low repulsion net 62 is arranged on the upstream side in the flow direction of the exhaust gas G from the protector 61. Although a part of the exhaust gas space is closed by the arrangement, a passage opening through which the exhaust gas G can pass is provided between each protector 61 and each low repulsion network 62. In the case of the present embodiment, the blockage ratio by each protector 61 in the second horizontal flue portion 13c is about 30%, but each protector 61 is installed in order to reduce the wear of the reducing agent supply portion 72. It was installed in anticipation of the pressure loss of the exhaust gas G.

By increasing the blockage ratio by each protector 61 and colliding most of the exhaust gas G with the low repulsion net 62, the solid particles A can fall and be collected more easily, and the pressure loss of the flow of the exhaust gas G can be increased. The increase is within the permissible range, and is not particularly limited. Further, as described in the second embodiment, by installing the protector 61 to which the low repulsion net 62 is attached by shifting the position between the upstream side and the downstream side of the exhaust gas G flow, the pressure loss of the exhaust gas G flow Since a large amount of exhaust gas G can be made to collide with the low repulsion net 62 and the solid particles A can be dropped without increasing the amount of the solid particles A, the solid particles A can be collected more easily. Further, since the low repulsion net 62 is provided on the upstream side of each protector 61, the wear due to the collision of the solid particles A of each protector 61 itself is suppressed by the synergistic effect with the low repulsion net 62, and each protector 61 It is possible to extend the life.

Further, in the second horizontal flue portion 13c, a soaring prevention net (soaring prevention member) 85 is arranged between the reducing agent supply portion 72 and the second hopper 56 along the upper surface of the bottom portion 71b. The soaring prevention member is a second perforated plate, and in the present embodiment, it is composed of a soaring prevention net 85. The soaring prevention net 85 suppresses the soaring of the solid particles A that have fallen to the bottom 71b, suppresses the remixing of the solid particles A into the exhaust gas G, and causes the solid particles A to move toward the second hopper 56 of the exhaust gas G. It moves and collects by the air flow.

The soaring prevention net 85 is substantially the same as the low repulsion net 62, and is a lattice-shaped low repulsion member formed of a material that elastically deforms in response to the collision of solid particles A. The soaring prevention net 85 is more preferably a grid-like one having a slightly larger opening than the low-resilience net 62 and having a large number of openings having a size through which the solid particles A can pass. The solid particles A that have fallen on the soaring prevention net 85 pass through the opening of the soaring prevention net 85 and fall on the upper surface of the bottom 71b, and the solid particles A are suppressed from soaring and remixed into the exhaust gas G while being suppressed. , Moves toward the second hopper 56 by the air flow of the exhaust gas G. The soaring prevention net 85 is arranged along the horizontal direction so as to be substantially parallel to the bottom portion 71b with a predetermined gap from the bottom portion 71b in the second horizontal flue portion 13c. Therefore, a flow path along the horizontal direction is formed between the soaring prevention net 85 and the bottom portion 71b of the second horizontal flue portion 13c. The predetermined gap between the soaring prevention net 85 and the bottom portion 71b of the second horizontal flue portion 13c is, for example, about 20 mm to 50 mm.

The soaring prevention member is not limited to the soaring prevention net 85. That is, the coefficient of restitution does not necessarily have to be smaller than that of the protector 61. For example, it may be a metal plate material, but it is composed of a perforated plate so that the solid particles A that have fallen to the bottom 71b by introducing the fluid force of the flow of the exhaust gas G can move toward the second hopper 56. Is desirable. Further, the soaring prevention net 85 may not be arranged in the lower part of the second horizontal flue portion 13c along the horizontal direction, but may be arranged so that the downstream side in the flow direction of the exhaust gas G is inclined vertically downward. As a result, the solid particles A that have fallen on the soaring prevention net 85 can move toward the second hopper 56 by gravity in addition to the fluid force of the flow of the exhaust gas G. Further, in the soaring prevention net 85, the second horizontal flue portion 13c is arranged from the reducing agent supply portion 72 to the second hopper 56, but it may be in front of the second hopper 56, and a part of the hopper is provided. The solid particles A that have fallen to the bottom 71b may not be soared and remixed into the exhaust gas G may be suppressed, and the solid particles A may be arranged so as to be closed, and the solid particles A may flow toward the second hopper 56. Moves and is collected by.

Here, the operation of the exhaust duct of the first embodiment, that is, the method of removing the solid particles A will be described.

In the method for removing solid particles of the first embodiment, the solid particles A contained in the exhaust gas G flowing through the second horizontal flue section 13c are arranged on the upstream side of the reducing agent supply section 72 in the flow direction of the exhaust gas G. The step of colliding with the net 62 and dropping the solid particles A colliding with the low-resilience net 62 and dropping the solid particles A are passed between the bottom 71b of the second horizontal flue portion 13c and the soaring prevention net 85 by the flow of the exhaust gas G. 2 It has a step of leading to the hopper 56.

That is, the exhaust gas G is the first vertical flue after the heat energy is recovered by the superheaters 41, 42, the reheaters 43, 44, and the economizers 45, 46, 47 (see FIG. 1) of the flue 13. The portion 13b is lowered, bent at a substantially right angle, and flows into the second horizontal flue portion 13c. At this time, the exhaust gas G is bent 90 degrees and flows, so that some large solid particles A are freely dropped and stored in the first hopper 55 due to the inertial force.

Part of the exhaust gas G flowing from the first vertical flue section 13b to the second horizontal flue section 13c flows through the passage opening between the reducing agent supply sections 72, while part of it flows upstream of the reducing agent supply section 72. It collides with the low-resilience net 62 arranged on the side. Here, the solid particles A contained in the exhaust gas G collide with the low repulsion net 62 to reduce the moving force of the solid particles A, and fall onto the bottom 71b of the second horizontal flue portion 13c due to its own weight. Therefore, some solid particles A suspended in the exhaust gas G are easily separated from the exhaust gas G and collected by the low-resilience net 62. Further, the protector 61 arranged in the reducing agent supply unit 72 suppresses the solid particles A from directly colliding with the reducing agent supply unit 72, and reduces the wear of the reducing agent supply unit 72 due to the collision of the solid particles A. It is a thing. This protector 61 is installed in anticipation of the pressure loss of the exhaust gas G, and even if the low repulsion network 62 is additionally installed in the protector 61, the pressure loss of the exhaust gas G does not increase. Therefore, the low repulsion network It is preferable as the installation location of 62. Then, the solid particles A that collide with the low-resilience net 62 and fall down flow from the passage opening between the low-resilience nets 62 to the flow path between the prevention net 85 and the bottom 71b of the second horizontal flue portion 13c. to go into. After that, the solid particles A in this flow path move to the downstream side due to the fluid force of the flow of the exhaust gas G and enter the second hopper 56. Therefore, the soaring prevention net 85 suppresses the soaring of the solid particles A, and the solid particles A collected by the low repulsion net 62 are suppressed from being remixed into the exhaust gas G.

After that, the exhaust gas G in which the solid particles A are reduced bends at a substantially right angle from the second horizontal flue portion 13c and flows into the second vertical flue portion 13d. At this time, the exhaust gas G is bent 90 degrees and flows, so that some large solid particles A are freely dropped and stored in the second hopper 56 due to the inertial force.

As described above, in the exhaust duct of the first embodiment, the exhaust gas G flows through the flue 13, the reducing agent supply device 51 provided with the reducing agent supply unit 72 for supplying the reducing agent to the flue 13, and smoke. A selective reduction catalyst 50 provided on the downstream side in the flow direction of the exhaust gas G from the reducing agent supply device 51 on the road 13 to promote the reaction between the reducing agent and the nitrogen oxides and reduce the nitrogen oxides in the exhaust gas G. A protector 61 provided on the upstream side in the flow direction of the exhaust gas G from the reducing agent supply unit 72 and a low repulsion network 62 provided on the upstream side in the flow direction of the exhaust gas G from the protector 61 and having a smaller repulsion coefficient than the protector 61. It is provided.

Therefore, when the exhaust gas G flows through the second horizontal flue portion 13c, if the solid particles A contained in the exhaust gas G collide with the low repulsion network 62, the amount of repulsion in the low repulsion network 62 is small. The moving force of the solid particles A is absorbed by the low repulsion net 62, and the solid particles A do not repel significantly and fall vertically downward due to their own weight. Therefore, the solid particles A suspended in the exhaust gas G can be easily collected by the low repulsion network 62, and the remixing of the collected solid particles A into the exhaust gas G can be suppressed, and as a result, the collected solid particles A can be suppressed. The deposition of solid particles A on the selective reduction catalyst 50 can be reduced.

In the exhaust duct of the first embodiment, as the reducing agent supply unit 72, the reducing agent injection pipe 81 arranged along the vertical direction in the second horizontal flue portion 13c and the flow direction of the exhaust gas G from the reducing agent injection pipe 81. A plurality of reducing agent injection nozzles 82 extending toward the downstream side of the above are provided, and the protector 61 is arranged on the upstream side in the flow direction of the exhaust gas G in the reducing agent injection pipe 81 and the plurality of reducing agent injection nozzles 82. Therefore, the collision of the solid particles A with the reducing agent injection pipe 81 and each reducing agent injection nozzle 82 can be suppressed to reduce wear, and the solid particles A are made to collide with the low repulsion net 62 provided in the protector 61. The solid particles A suspended in the exhaust gas G can be reduced by dropping the particles. The protector 61 is installed in anticipation of the pressure loss of the exhaust gas G, and even if the low repulsion net 62 is additionally installed in the protector 61, the pressure loss of the exhaust gas G does not further increase. Further, by providing the low repulsion net 62 on the upstream side of the protector 61, wear due to collision of the solid particles A of the protector 61 itself can be suppressed, and the life of the protector 61 can be extended.

In the exhaust duct of the first embodiment, the low-resilience portion is a low-resilience net 62 as the first perforated plate. Therefore, by using the protector 61 and the low-resilience net 62 as separate members, it is possible to firmly manufacture the protector 61 that collides the solid particles A and prevents the reducing agent supply unit 72 from being worn, while the solid particles A can be firmly manufactured. The low-resilience net 62, which collides with and drops the particles, can be manufactured according to its function so that the amount of repulsion is small. The low-resilience portion (low-resilience net 62) can be easily manufactured at low cost with a simple configuration, and the collision force of the solid particles A can be easily absorbed and dropped.

In the exhaust duct of the first embodiment, a gap is provided between the protector 61 and the low repulsion net 62. Therefore, even the solid particles A through which the low-resilience net 62 has passed through the gap can be easily collected because they repel the surface of the protector 61, collide with the low-resilience net 62, and fall. Further, a pressure loss of the exhaust gas G passing through the low repulsion network 62 is generated, and a region is formed in which the flow of the exhaust gas G in the gap is remarkably decelerated, and the solid particles A colliding with the low repulsion network 62 and falling to the exhaust gas G The re-mixing is suppressed, and the solid particles A colliding with the low-resilience net 62 can be effectively dropped.

In the exhaust duct of the first embodiment, a soaring prevention net 85 as a second perforated plate is arranged between the reducing agent supply portion 72 and the second hopper 56 along the bottom portion 71b of the second horizontal flue portion 13c. ing. Therefore, a part of the solid particles A contained in the exhaust gas G collides with the low repulsion network 62, and the collision force is absorbed by the low repulsion network 62 and falls. However, the dropped solid particles A are the exhaust gas G. Due to the flow, it flows through the flow path between the soaring prevention net 85 and the bottom 71b and enters the second hopper 56, and the solid particles A dropped by the low repulsion net 62 are soared by the exhaust gas G flowing through the exhaust gas flow path 13. It can be stored in the second hopper 56 without being remixed into the exhaust gas G, and the solid particles A suspended in the exhaust gas G can be easily collected.

In the exhaust duct of the first embodiment, the soaring prevention member is a soaring prevention net 85 having a large number of openings having a size through which the solid particles A can pass. Therefore, the solid particles A that have fallen on the upper surface of the soaring prevention net 85 fall from a large number of holes to the upper surface of the bottom 71b and enter the second hopper 56 due to the flow of the exhaust gas G, so that the solid particles A enter the upper surface of the soaring prevention net 85. Accumulation of solid particles A can be suppressed.

Further, in the boiler of the first embodiment, the fireplace 11 which has a hollow shape and is installed along the vertical direction, the combustion device 12 arranged in the fireplace 11, and the upper part of the fireplace 11 in the vertical direction are connected. It is equipped with an exhaust duct.

Therefore, the combustion device 12 blows fuel into the fireplace 11 to form a flame, and the generated combustion gas flows into the flue 13. The combustion gas exchanges heat with a heat exchanger arranged in the flue 13 to become exhaust gas G, which flows through the flue 13. At this time, when the exhaust gas G and the solid particles A contained in the exhaust gas G collide with the low repulsion network 62 arranged in the flue 13, the moving force of the solid particles A is absorbed by the low repulsion network 62 and the solid particles. A does not repel significantly and falls vertically downward due to its own weight. Therefore, by collecting the solid particles A suspended in the exhaust gas G by the low repulsion network 62, the solid particles A suspended in the exhaust gas G are reduced, and the deposition of the solid particles A on the selective reduction catalyst 50 is reduced. Can be made to. As a result, the purification performance of the exhaust gas G by the selective reduction catalyst 50 can be maintained, the durability can be improved, and the increase in the pressure loss of the exhaust duct can be suppressed to discharge the exhaust gas G such as a blower. It is possible to suppress an increase in power for the purpose.

Further, in the method for removing solid particles of the first embodiment, the solid particles A contained in the exhaust gas G flowing through the second horizontal flue portion 13c are moved upstream from the reducing agent supply portion 72 in the flow direction of the exhaust gas G. The step of colliding with the arranged low-resilience portion 62 and dropping it onto the bottom 71b of the second horizontal flue portion 13c, and the solid particles A falling on the bottom 71b of the second horizontal flue portion 13c are caused by the flow of exhaust gas G. 2 It has a step of leading to the second hopper 56 through between the bottom portion 71b of the horizontal flue portion 13c and the soaring prevention net 85.

Therefore, by installing the low repulsion net 62 on the protector 61 that reduces the wear of the reducing agent supply unit 72, the solid particles A suspended in the exhaust gas G can be easily collected by the low repulsion net 62, and at the same time, the solid particles A can be easily collected by the low repulsion net 62. The remixing of the collected solid particles A into the exhaust gas G can be suppressed, and as a result, the deposition of the solid particles A on the selective reducing catalyst 50 can be reduced. Further, since the protector 61 is installed in anticipation of the pressure loss of the exhaust gas G, the pressure loss of the exhaust gas G does not further increase even if the low repulsion network 62 is additionally installed, so that the boiler performance is not affected. ..

[Second Embodiment]
FIG. 7 is a schematic side view showing the exhaust duct of the second embodiment. The members having the same functions as those of the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 7, the exhaust duct of the second embodiment includes a flue 13, a selective reduction catalyst 50 (see FIG. 1), a reducing agent supply device 91, and protectors (protective members) 101, 102, 103. And a low-resilience net (low-resilience portion) 104.

The reducing agent supply device 91 is provided in the second horizontal flue portion 13c. The reducing agent supply device 91 includes a reducing agent supply unit 92, a reducing agent supply pipe 73, a reducing agent supply source 74, and an on-off valve 75. The reducing agent supply unit 92 is arranged inside the second horizontal flue unit 13c, and is composed of a reducing agent injection pipe and a plurality of reducing agent injection nozzles.

The reducing agent injection pipe is divided into a plurality of parts in order to adjust the injection amount by a valve installed upstream of the reducing agent injection pipe so that the injection amount of the reducing agent is optimized in the cross-sectional direction of the exhaust duct to be installed. Need to keep. It is composed of a plurality of (three in this embodiment) split reducing agent injection pipes 93, 94, 95 whose length becomes shorter toward the downstream side in the flow direction of the exhaust gas G. A plurality of the divided reducing agent injection pipes 93, 94, 95 are arranged along the vertical direction at the second horizontal flue portion 13c and at predetermined intervals in the horizontal direction. The divided reducing agent injection pipes 93, 94, and 95 are arranged at predetermined intervals in the flow direction of the exhaust gas G, the upper end of each is supported by the ceiling portion 71a, and the lower end portion extends toward the bottom portion 71b. There is. That is, the lower end of the split reducing agent injection pipe 93 on the most upstream side is supported by the bottom 71b of the second horizontal flue portion 13c, and the lower end of the split reducing agent injection pipe 94 has the second horizontal flue portion 13c. The lower end of the split reducing agent injection pipe 9 is located in the middle portion and is located in the upper portion of the second horizontal flue portion 13c. In each of the divided reducing agent injection pipes 93, 94, 95, a plurality of reducing agent injection nozzles 96, 97, 98 are fixed toward the downstream side in the flow direction of the exhaust gas G, respectively.

The protectors 101, 102, and 103 constituting the protective member are provided on the upstream side of the reducing agent supply unit 92 in the flow direction of the exhaust gas G. The protector 101 is arranged on the upstream side in the flow direction of the exhaust gas G in the reducing agent injection pipe 93 and the plurality of reducing agent injection nozzles 96, and the protector 102 is the exhaust gas G in the reducing agent injection pipe 94 and the plurality of reducing agent injection nozzles 97. The protector 103 is arranged on the upstream side in the flow direction of the exhaust gas G in the reducing agent injection pipe 95 and the plurality of reducing agent injection nozzles 98. The protectors 101, 102, and 103 of the second embodiment have substantially the same configuration as the protector 61 of the first embodiment.

The low-resilience portion is a first perforated plate, and in the present embodiment, the low-resilience portion is composed of a low-resilience net 104 as a wire mesh member. The low-repulsion net 104 has a smaller coefficient of restitution than the protector 101, and is provided on the upstream side of the protector 101 in the flow direction of the exhaust gas G. In the present embodiment, the low repulsion net 104 is not provided on the protectors 102 and 103, but the frequency of collision with the solid particles A is low, and the collection amount of the solid particles A is not significantly increased. The low-resilience net 104 may be provided on the protectors 102 and 103. Further, the low-resilience net 104 may be fixed by providing a gap between the protectors 101, 102, and 103. The low-resilience net 104 of the second embodiment has substantially the same configuration as the low-resilience net 62 of the first embodiment.

Further, in the second horizontal flue portion 13c, a soaring prevention net 85 is arranged between the reducing agent supply portion 92 and the second hopper 56 along the upper surface of the bottom portion 71b.

Therefore, part of the exhaust gas G flowing through the second horizontal flue portion 13c flows through the passage opening between the reducing agent supply units 92, while part of the exhaust gas G flows through the divided reducing agent injection pipe 93 and the reducing agent supply unit 92 in the reducing agent supply unit 92. It collides with the low-resilience net 104 arranged on the upstream side of each reducing agent injection nozzle 96. Here, the solid particles A contained in the exhaust gas G collide with the low repulsion net 104 to reduce the moving force of the solid particles A, and fall onto the bottom 71b of the second horizontal flue portion 13c due to its own weight. Therefore, some solid particles A suspended in the exhaust gas G are separated and collected by the low-resilience net 104. Further, the solid particles A are separated by the split reducing agent injection pipes 93, 94, 95 and the protectors 101, 102, 103 located upstream of the split reducing agent injection nozzles 96, 97, 98. , 95 and each reducing agent injection nozzle 96, 97, 98 are suppressed from directly colliding with each other, and wear due to the collision of the solid particles A is reduced. Then, the solid particles A that collide with the low-resilience net 104 and fall are flown from the passage opening between the low-resilience nets 104 to the flow path between the prevention net 85 and the bottom 71b of the second horizontal flue portion 13c. to go into. After that, the solid particles A in this flow path move to the downstream side due to the fluid force of the exhaust gas G and enter the second hopper 56. Therefore, the soaring prevention net 85 suppresses the soaring of the solid particles A, and the remixing of the collected solid particles A into the exhaust gas G is suppressed.

In the exhaust duct of the second embodiment, a plurality of split reducing agent injection pipes 93, 94, 95 having a length shortened toward the downstream side in the flow direction of the exhaust gas G are provided, and protectors 101, 102, 103 are provided. The divided reducing agent injection pipes 93, 94, 95 and the reducing agent injection nozzles 96, 97, 98 are arranged on the upstream side in the flow direction of the exhaust gas G, and the low repulsion network 104 is at least on the most upstream side in the flow direction of the exhaust gas G. It is arranged on the upstream side in the flow direction of the exhaust gas G of the protector 101 in the divided reducing agent injection pipe 93.

Therefore, the collision of the solid particles A with the divided reducing agent injection pipes 93, 94, 95 and the reducing agent injection nozzles 96, 97, 98 can be suppressed to reduce wear, and at least the most upstream side is arranged. By arranging 104 parts of the low repulsion network on the upstream side in the flow direction of the exhaust gas G in the split reducing agent injection pipe 93, the solid particles A collide with the low repulsion network 104 and are dropped to float in the exhaust gas G. Solid particles A can be reduced.

As a modification of the second embodiment, the divided reducing agent injection pipes 93, 94, 95 and the protectors 101, 102, 103 installed on the upstream side in the flow direction of the exhaust gas G are attached to the cross section of the second horizontal flue portion 13c. The installation position is shifted in the horizontal direction. That is, each of the split reducing agent injection pipes 93, 94, 95 is shifted in the horizontal direction of the cross section (vertical direction on the paper surface of FIG. 7) by approximately the width of each protector 101, 102, 103 toward the downstream of the exhaust gas G. is set up. When viewed from the upstream side of the exhaust gas G in the second horizontal flue portion 13c, the protectors 101, 102, 103 attached to the divided reducing agent injection pipes 93, 94, 95 are arranged so as not to overlap and hide. ..

The low-resilience net 104 is arranged on the upstream side in the flow direction of the exhaust gas G in the protectors 101, 102, 103 of the divided reducing agent injection pipes 93, 94, 95. In this way, by installing the protector 61 to which the low repulsion net 62 is attached by shifting the position between the upstream side and the downstream side of the exhaust gas flow, the protectors 101, 102 in the cross section of the second horizontal flue portion 13c, Since the blockage ratio by 103 is not increased, the pressure loss of the exhaust gas flow is not increased, and a large amount of exhaust gas G can be made to collide with the low repulsion net 104 to drop the solid particles A, so that the solid particles A can be collected more easily. can do.

In the above-described embodiment, the protective member of the present invention is used as the protector 61, and the low-resilience portion is provided as a separate member as the low-resilience net 62. However, the present invention is not limited to this configuration, and the protective member and the low-resilience portion are provided. And may be configured as one member. For example, the low repulsion portion may be integrally formed by forming the flat surface portion of the protector 61 on the upstream side in the flow direction of the exhaust gas G into an uneven shape.

Further, in the above-described embodiment, the reducing agent supply device 51, the protector 61, and the low repulsion net 62 are provided in the second horizontal flue portion 13c, but the position is not limited to this. For example, it may be arranged in the second vertical flue portion 13d.

Further, in the above-described embodiment, the boiler of the present invention is a coal-fired boiler, but the solid fuel may be a boiler using biomass, petroleum coke, petroleum residue, or the like. Further, the fuel can be used not only for solid fuels but also for oil-fired boilers such as heavy oils for boilers in which solid particles A are generated in the exhaust gas G, and further, gas (by-product gas) can also be used as fuel. Can be used. It can also be applied to co-firing of these fuels.

10 Coal-fired boiler (boiler)
11 Fireplace 12 Combustion device 13 Flue (exhaust gas passage)
13a 1st horizontal flue 13b 1st vertical flue 13c 2nd horizontal flue 13d 2nd vertical flue 13e 3rd horizontal flue 13f 3rd vertical flue 21,22,23,24, 25 Combustion burner 41, 42, 43 Superheater (heat exchanger)
44,45 Reheater (heat exchanger)
46,47 Economizer (heat exchanger)
48 Gas duct 50 Selective reduction catalyst (denitration catalyst)
51, 91 Reducing agent supply device 55 1st hopper 56 2nd hopper 61, 101, 102, 103 Protector (protective member)
62,104 Low-resilience net (low-resilience part, first perforated plate)
72,92 Reducing agent supply section 81, 93, 94, 95 Reducing agent injection pipe 93, 94, 95 Divided reducing agent injection pipe (reducing agent injection pipe)
82, 96, 97, 98 Reducing agent injection nozzle 83 Support member 85 Soaring prevention net (Flying prevention member, second perforated plate)
G Exhaust gas A Solid particles

Claims (10)

An exhaust gas passage through which exhaust gas containing solid particles generated by combustion of fuel flows,
A reducing agent supply device having a reducing agent supply unit that supplies a reducing agent to the exhaust gas in the exhaust gas passage, and a reducing agent supply device.
A denitration catalyst provided downstream of the reducing agent supply device in the exhaust gas passage in the flow direction of the exhaust gas to promote the reaction between the reducing agent and nitrogen oxides in the exhaust gas.
A protective member provided in a horizontal portion on the upstream side in the flow direction of the exhaust gas from the reducing agent supply unit to prevent the exhaust gas from colliding with the reducing agent supply unit.
A low-repulsion portion provided in the horizontal portion on the upstream side in the flow direction of the exhaust gas from the protective member and having a smaller coefficient of restitution with the solid particles than the protective member.
With
A plurality of the reducing agent supply unit and the protective member are arranged at predetermined intervals in the horizontal direction intersecting the flow direction of the exhaust gas, and the low repulsion unit is spaced at a predetermined interval in the horizontal direction intersecting the flow direction of the exhaust gas. The low repulsion portion is arranged at a position where all the protective members are hidden when viewed from the upstream side in the flow direction of the exhaust gas on the upstream side of the protective member .
The exhaust duct is characterized by that. The reducing agent supply unit includes a plurality of reducing agent injection nozzles for injecting the reducing agent into the exhaust gas, and a split reducing agent injection pipe for supplying the reducing agent to the plurality of reducing agent injection nozzles. The plurality of reducing agent injection nozzles are arranged on the outer surface of the pipe toward the downstream side in the flow direction of the exhaust gas.
The protective member is arranged on the upstream side in the exhaust gas flow direction in the split reducing agent injection pipe and the plurality of reducing agent injection nozzles, and the low repulsion portion is arranged at least on the most upstream side in the exhaust gas flow direction. The exhaust duct according to claim 1, wherein the exhaust duct is arranged on the upstream side in the flow direction of the exhaust gas from the protective member. The claim is characterized in that the split reducing agent injection pipe and the protective member are arranged so as to be offset in the horizontal direction intersecting the flow direction of the exhaust gas, and the low repulsion portion is arranged on the upstream side of the protective member. The exhaust duct according to 2. The exhaust duct according to any one of claims 1 to 3, wherein the low-resilience portion is formed of a first perforated plate. The exhaust duct according to claim 4, wherein the first perforated plate is made of a wire mesh member. Between the first perforated plate and the protective member, the solid particles that have passed through the first perforated plate repel each other on the surface of the protective member and collide with the first perforated plate to reduce the amount of repulsion. The exhaust duct according to claim 4 or 5, wherein a gap for dropping is provided. An exhaust gas passage through which exhaust gas containing solid particles generated by combustion of fuel flows,
A reducing agent supply device having a reducing agent supply unit that supplies a reducing agent to the exhaust gas in the exhaust gas passage, and a reducing agent supply device.
A denitration catalyst provided downstream of the reducing agent supply device in the exhaust gas passage in the flow direction of the exhaust gas to promote the reaction between the reducing agent and nitrogen oxides in the exhaust gas.
A protective member provided in a horizontal portion on the upstream side in the flow direction of the exhaust gas from the reducing agent supply unit to prevent the exhaust gas from colliding with the reducing agent supply unit.
A low-repulsion portion provided in the horizontal portion on the upstream side in the flow direction of the exhaust gas from the protective member and having a smaller coefficient of restitution with the solid particles than the protective member.
With
The exhaust gas passage includes a horizontal portion of the exhaust gas passage through which the exhaust gas flows in the horizontal direction and a vertical portion of the exhaust gas passage which is connected to the downstream side of the horizontal portion in the flow direction of the exhaust gas and in which the exhaust gas flows in the vertical direction. The reducing agent supply unit is arranged in the horizontal portion, and a hopper for collecting the solid particles is provided at the connecting portion between the horizontal portion and the vertical portion, and between the reducing agent supply unit and the hopper. Then, a soaring prevention member is arranged by providing a predetermined gap with the bottom surface of the horizontal portion.
The exhaust duct is characterized by that. The exhaust duct according to claim 7, wherein the soaring prevention member is made of a second perforated plate. A fireplace that has a hollow shape and is installed along the vertical direction,
The combustion device arranged in the fireplace and
The exhaust duct according to any one of claims 1 to 8, which is connected to the upper part of the fireplace in the vertical direction.
A boiler characterized by being equipped with. In the method of removing solid particles contained in the exhaust gas flowing through the exhaust gas passage,
A low-repulsion portion, a protective member, and a soaring prevention member are arranged along the flow direction of the exhaust gas in the horizontal portion of the exhaust gas passage.
The solid particles are dropped by colliding with the low repulsion portion arranged on the upstream side in the flow direction of the exhaust gas from the protective member provided in the reducing agent supply portion.
The solid particles that collide with the low-repulsion portion and fall are passed between the bottom surface of the exhaust gas passage and the soaring prevention member installed with a gap by the flow of exhaust gas, and the exhaust gas flow of the low-repulsion portion. The solid particles are collected by a hopper provided on the downstream side.
A method for removing solid particles.

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