KR102655870B1 - Circulating fluidized bed combustion system - Google Patents

Abstract

In the circulating fluidized bed combustion system according to an embodiment of the present invention, the primary oxidant supply unit is connected to the combustion furnace at a first point, the secondary oxidant supply unit is connected to the combustion furnace at a second point, and the tertiary oxidant supply unit is connected to the combustion furnace at a third point. At this point it is connected to the combustion furnace. The first ammonia supply may be connected to the combustion furnace at a fourth point and configured to supply ammonia. The fourth point may be lower than the second point. By supplying the oxidizing agent at a predetermined ratio from the primary oxidizing agent supply section and the tertiary oxidizing agent supply section, relatively high temperature heat can be generated by the amount of solids remaining at the bottom of the combustion furnace, and this heat can be used to vaporize the supplied ammonia and improve combustibility. It is possible to form a circulating fluidized bed combustion system with a high ammonia co-combustion rate.

Description

Circulating fluidized bed combustion system {CIRCULATING FLUIDIZED BED COMBUSTION SYSTEM}

The present invention relates to a circulating fluidized bed combustion system, and more specifically, to a circulating fluidized bed combustion system in which co-combustion of fuel containing ammonia is performed.

Circulating fluidized bed boiler (CFB boiler) can utilize biomass and waste and has easy fuel flexibility.

A method that can reduce nitrogen oxides in a circulating fluidized bed combustion furnace without injecting a reducing agent (furnace denitrification technology) is a multi-stage combustion (air-staging, or staging combustion) technique.

The multi-stage combustion technique involves injecting combustion air in portions according to the height of the combustion furnace.

By applying the multi-stage combustion technique, the primary oxidant, secondary oxidant, and tertiary oxidant can be injected at different heights, and in the multi-stage combustion technique, the tertiary oxidant is injected at a predetermined flow rate while reducing the flow rate of the primary oxidant. I do it.

In circulating fluidized bed combustion, the flow rate of the primary oxidant can play a role in circulating the fluidized sand, which is the heat chain.

If the primary oxidant flow rate is reduced, oxidation cannot be sufficiently achieved to the level at which the tertiary oxidant flow rate is supplied, and a reduction reaction occurs, resulting in a decrease in NO and an increase in CO. Accordingly, in order to reduce CO, a tertiary oxidant is supplied to create an oxidation zone where an oxidant reaction occurs.

In circulating fluidized bed combustion, solids serve as a heat medium. If the flow rate of the primary oxidant is reduced, the heat medium cannot circulate properly and the amount of solids retained increases, which may cause the problem of increasing the temperature at the bottom of the combustion furnace.

Additionally, when the temperature at the bottom of the combustion furnace increases, agglomeration and slagging of solid materials may occur.

On the other hand, ammonia has a very slow combustion speed compared to other fuels and has a relatively high self-ignition temperature, so in order to apply it to a boiler, preheating of ammonia is required and a method to improve the combustion speed is needed.

Ammonia fuel has a low risk of flammability, but has a very high risk, so it must be completely burned within the combustion furnace in order to be applied to a boiler. If combustion of ammonia is not complete, unreacted ammonia (Slip NH ₃ ) may be generated.

This disclosure describes a circulating fluidized bed combustion system that can improve the combustibility of ammonia by the high temperature at the bottom of the combustion furnace due to multi-stage combustion in a circulating fluidized bed boiler.

This disclosure describes a circulating fluidized bed combustion system that supplies ammonia to a solid particle transfer line circulating from a loop seal to a combustion chamber and improves combustibility through vaporization and preheating of ammonia.

This disclosure describes a circulating fluidized bed combustion system that can reduce nitrogen oxides generated during ammonia combustion and suppress ammonia slip (NH ₃ Slip).

The present disclosure describes a circulating fluidized bed combustion system that is capable of controlling the temperature of the bottom of the combustion furnace and preventing agglomeration of solid materials in the bottom.

This disclosure describes a circulating fluidized bed combustion system that can reduce coal usage and carbon dioxide emissions by increasing the ammonia co-combustion rate.

A circulating fluidized bed combustion system according to one aspect of the subject matter described in the present application includes a combustion furnace in which a combustion reaction occurs; a primary oxidant supply unit connected to the combustion furnace at a first point and supplying a first oxidant; a secondary oxidant supply unit connected to the combustion furnace at a second point higher than the first point and supplying a second oxidant and fuel; a third oxidant supply unit connected to the combustion furnace at a third point higher than the second point and supplying a third oxidant; and a first ammonia supply unit connected to the combustion furnace at a fourth point equal to or lower than the second point and configured to supply ammonia.

The first ammonia supply unit may be connected to the combustion furnace in an area where the heat medium stays.

The circulating fluidized bed combustion system includes a cyclone connected to the upper side of the combustion furnace and configured to separate exhaust gas and solid particles discharged from the combustion furnace; A loop seal through which solid particles separated from the cyclone are introduced; A downcomer connecting the roof seal and the combustion furnace to allow the solid particles to move; And it may include a second ammonia supply unit connected to the downcomer and configured to supply ammonia.

A circulating fluidized bed combustion system according to one aspect of the subject matter described in the present application includes a combustion furnace in which a combustion reaction occurs; A cyclone connected to the upper side of the combustion furnace and configured to separate exhaust gas and solid particles discharged from the combustion furnace; A loop seal through which solid particles separated from the cyclone are introduced; A downcomer connecting the roof seal and the combustion furnace to allow the solid particles to move; a primary oxidant supply unit connected to the combustion furnace at a first point and supplying a first oxidant; a secondary oxidant supply unit connected to the combustion furnace at a second point higher than the first point and supplying a second oxidant and fuel; a third oxidant supply unit connected to the combustion furnace at a third point higher than the second point and supplying a third oxidant; And it may include a second ammonia supply unit connected to the downcomer and configured to supply ammonia.

The downcomer is connected to the combustion furnace at a fifth point, and the fifth point may be higher than the first point and lower than the second point.

The cyclone includes a first cyclone connected to the combustion furnace; and a second cyclone connected to the first cyclone and configured to separate fly ash from the exhaust gas discharged from the first cyclone, wherein the loop seal seals the solid particles separated from the first cyclone. It can be made to flow in.

Ammonia may be supplied in a liquid state from the first ammonia supply unit.

Ammonia may be supplied in a liquid state from the second ammonia supply unit.

The supply ratio of each of the first oxidizing agent, the second oxidizing agent, and the third oxidizing agent may be 65 to 80:5 to 15:10 to 25.

The fuel may be made of any one or more of biomass, sub-bituminous coal, and lignite.

In the circulating fluidized bed combustion system according to an embodiment of the present invention, the primary oxidant supply unit is connected to the combustion furnace at a first point, the secondary oxidant supply unit is connected to the combustion furnace at a second point, and the tertiary oxidant supply unit is connected to the combustion furnace at a third point. connected to the combustion furnace. The first ammonia supply may be connected to the combustion furnace at a fourth point and configured to supply ammonia. The fourth point is made equal to or lower than the second point. By supplying the oxidizing agent at a predetermined ratio from the primary oxidizing agent supply section and the tertiary oxidizing agent supply section, relatively high temperature heat can be generated due to the amount of solids remaining at the bottom of the combustion furnace, and this heat is a heat source for vaporizing the supplied ammonia and improving combustibility. It can be used as

In the circulating fluidized bed combustion system according to an embodiment of the present invention, the second ammonia supply unit may be connected to the downcomer and supply ammonia. Therefore, ammonia can be supplied to the solid particle transfer line circulating from the loop seal to the combustion furnace, and combustibility can be improved through vaporization and preheating of the ammonia.

Specific effects and additional effects achieved by the circulating fluidized bed combustion system according to embodiments of the present invention are described below.

Figure 1 is a diagram schematically showing a circulating fluidized bed combustion system according to an embodiment of the present invention.
Figure 2 is a diagram schematically showing a partial configuration of a circulating fluidized bed combustion system according to an embodiment of the present invention.
Figure 3 is a diagram illustrating multi-stage combustion in a combustion furnace in a circulating fluidized bed combustion system according to an embodiment of the present invention.
Figure 4 is a graph showing the temperature in the combustion furnace according to the ratio of the supply amounts of the first, second, and third oxidants in the circulating fluidized bed combustion system.

Hereinafter, in order to explain the present invention in more detail, embodiments according to the present invention will be described in more detail with reference to the accompanying drawings. Like reference numerals refer to like elements throughout the detailed description.

Figure 1 is a diagram schematically showing a circulating fluidized bed combustion system 1 according to an embodiment of the present invention.

Figure 2 is a diagram schematically showing a partial configuration of a circulating fluidized bed combustion system 1 according to an embodiment of the present invention.

Figure 3 is a diagram explaining the multi-stage combustion of the combustion furnace 100 in the circulating fluidized bed combustion system 1 according to an embodiment of the present invention.

The circulating fluidized bed combustion system 1 according to an embodiment of the present invention includes a combustion furnace 100, a primary oxidant supply unit 210, a secondary oxidant supply unit 220, a tertiary oxidant supply unit 230, and a first ammonia supply unit. It can be done including (510).

A combustion reaction occurs inside the combustion furnace 100. The combustion furnace 100 may be formed in a furnace shape. Inside the combustion furnace 100, silica sand is provided, which serves as a heat medium during combustion of the circulating fluidized bed. As the fluidized sand made of sand, a high-temperature fluidized bed material, circulates, it comes into contact with the fuel introduced into the combustion furnace 100. Combustion may be performed in the combustion furnace 100.

The primary oxidant supply unit 210 is connected to the combustion furnace 100 at the first point P1 and is configured to supply the first oxidant to the combustion furnace 100. The first oxidizing agent may be air and/or oxygen that flows into the lower part of the combustion furnace 100 and is injected into the combustion furnace 100 through the nozzle of the distribution plate 110. The primary oxidant supply unit 210 may be formed in the form of a pipe that supplies air.

The secondary oxidant supply unit 220 is connected to the combustion furnace 100 at the second point P2 and is configured to supply the second oxidant and fuel. The second point (P2) is higher than the first point (P1). The second oxidizing agent may be air and/or oxygen injected into the combustion furnace 100 along with the fuel from the upper side of the distribution plate 110. The secondary oxidant supply unit 220 may be formed in the form of a pipe that supplies fuel and air.

The third oxidizing agent supply unit 230 is connected to the combustion furnace 100 at the third point P3 and is configured to supply the third oxidizing agent. The third point (P3) is higher than the second point (P2). The third oxidizing agent may be air and/or oxygen injected into the combustion furnace 100 from the upper side of the dispersion plate 110 through a separate supply pipe. The tertiary oxidant supply unit 230 may be formed in the form of a pipe that supplies air.

To supply the oxidizing agent, the circulating fluidized bed combustion system 1 may include an air tank 201 and a first blower 202 (forced draft fan). The air tank 201 may be connected to the combustion furnace 100 through each pipe, and combustion air flows into the air tank 201 by the operation of the first blower 202 connected to the air tank 201, and the air The pressure within the tank 201 may be maintained in a predetermined range.

Fuel is supplied through the secondary oxidant supply part 220 from the upper part of the heat medium area 120 formed in the lower part of the combustion furnace 100, and fuel is supplied through the primary oxidant supply part 210 from the lower part of the combustion furnace 100. By the first oxidant, which is air for primary combustion, the supplied fuel is mixed and fluidized with the heat medium and burned, generating NO and CO.

The first ammonia supply unit 510 is connected to the combustion furnace 100 at the fourth point P4 and is configured to supply ammonia to the combustion furnace 100. The first ammonia supply unit 510 may be formed in the form of a pipe that supplies ammonia.

The fourth point P4 may be formed to have a predetermined height h upward from the distribution plate 110.

In one embodiment, the fourth point P4 may be the same as the second point P2.

In the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, the fourth point P4 may be lower than the second point P2. The first ammonia supply unit 510 may be connected to the combustion furnace 100 in the area 120 where the heat medium stays. That is, the fourth point P4 may be formed at the same height as the area 120 where the heat medium stays.

In the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, an ammonia tank 500 may be provided to store and supply ammonia. The first ammonia supply unit 510 and the second ammonia supply unit 520 may each be connected to the ammonia tank 500.

Ammonia may be supplied in liquid form from the first ammonia supply unit 510.

In Figure 3 (a) is a diagram showing a case where multi-stage combustion is not applied in the circulating fluidized bed combustion system, and (b) in Figure 3 is a diagram showing a case where multi-stage combustion is applied in the circulating fluidized bed combustion system (1).

If multi-stage combustion is not applied in circulating fluidized bed combustion, the third oxidant is not supplied. That is, only the first oxidizing agent and the second oxidizing agent are supplied. At this time, only an oxidation region exists within the combustion furnace 100, as shown in (a) of FIG. 3.

When applying multi-stage combustion in circulating fluidized bed combustion, the supply amount of the first oxidant is reduced compared to the case where multi-stage combustion is not applied, and the supply amount of the third oxidant is used in consideration of the reduced supply amount of the first oxidant, As shown in Figure 3 (b), based on the position of the tertiary oxidant supply unit 230, a reduction zone is formed below and an oxidation zone is formed above. As the reduction zone is formed, NO reacts with CO and char generated in the reduction zone and is easily reduced to N ₂ , so the emission of NO decreases, but the oxidation zone is relatively reduced, so CO cannot be sufficiently oxidized to CO _2. The amount of CO generated increases.

In the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, the amount of CO generated can be reduced by appropriately adjusting the supply position of the third oxidant.

When multi-stage combustion is applied to circulating fluidized bed combustion, the amount of air supplied to the first oxidant is reduced, preventing proper circulation of the solid material that serves as a heating medium in circulating fluidized bed combustion, and as the amount of heat medium remaining increases, the combustion furnace 100 Bottom temperature may increase.

In the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, ammonia is supplied to the combustion furnace 100 at the fourth point P4 through the first ammonia supply unit 510, and ammonia is supplied to the combustion furnace 100. Combustibility is improved by preheating and vaporization by the temperature of the lower part, and a circulating fluidized bed combustion system (1) with excellent ammonia co-combustion rate can be provided.

also. Ammonia is preheated and some of it is cracked, and even if only a small amount of hydrogen is generated, the combustion rate of hydrogen is very high, so ammonia can be burned better by the heat released during hydrogen combustion. In addition, as the ammonia co-firing rate increases, the amount of coal used can be reduced, and a carbon dioxide reduction effect can be obtained in proportion to the increase in the ammonia co-firing rate.

Depending on the embodiment, ammonia may be cracked by adding some additives (catalysts) that can replace the flow sand, and Ru, Ni, Co, Fe, etc. may be used as catalysts for ammonia cracking.

The circulating fluidized bed combustion system 1 according to an embodiment of the present invention includes a cyclone 310, a loop seal 320, a downcomer 330, and a second ammonia supply unit 520. This can be done.

The cyclone 310 is connected to the upper side of the combustion furnace 100 and is configured to separate solid particles from a mixture of exhaust gas and solid particles discharged from the combustion furnace 100. The mixture of exhaust gas and solid particles introduced into the cyclone 310 may form a vortex within the cyclone 310. In this process, solid particles may hit the inner wall of the cyclone 310 by centrifugal force and then fall by gravity. On the other hand, the exhaust gas may be separated from the solid particles in the cyclone 310 and then discharged from the cyclone 310 while rising.

In the cyclone 310, the flowing sand discharged from the combustion furnace 100 can be collected, and this flowing sand can be moved to the loop seal 320. The loop seal 320 is configured to allow solid particles separated from the cyclone 310 to flow in.

The downcomer 330 is configured to connect the loop seal 320 and the combustion furnace 100 to allow solid particles to move. The downcomer 330 may be in the form of a pipe.

Some of the flowing sand transferred from the cyclone 310 to the loop seal 320 may be recirculated into the combustion furnace 100. The fluidized sand is circulated while sequentially passing through the combustion furnace 100, the cyclone 311, the loop seal 320, and the combustion furnace 100, so that overall combustion and temperature increase can be achieved.

The second ammonia supply unit 520 is connected to the downcomer 330 and supplies ammonia to the downcomer 330. The second ammonia supply unit 520 may be formed in the form of a pipe that supplies ammonia.

Downcomer 330 is connected to the combustion furnace 100 at the fifth point (P5). The fifth point (P5) may be higher than the first point (P1) and lower than the second point (P2).

In the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, the cyclone 310 may be divided into a first cyclone 311 and a second cyclone 312.

The first cyclone 311 is connected to the combustion furnace 100. The first cyclone 311 is connected to the upper side of the combustion furnace 100 and is configured to separate the exhaust gas and solids discharged from the combustion furnace 100.

The second cyclone 312 is connected to the first cyclone 311, and the exhaust gas discharged from the first cyclone 311 flows into the second cyclone 312. In the second cyclone 312, fly ash that was not separated in the first cyclone 311 is separated from the exhaust gas.

The loop seal 320 may be configured to allow solid particles separated from the first cyclone 311 to flow in. The loop seal 320 is connected to the lower part of the first cyclone 311, and the solids separated from the first cyclone 311 pass through the loop seal 320 and flow into the fluidization area of the combustion furnace 100. .

Ammonia may be supplied in liquid form from the second ammonia supply unit 520.

As described above, in the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, the second ammonia supply unit 520 may be connected to the downcomer 330 and may be configured to supply ammonia, and may be configured to supply ammonia in the loop seal 320. Ammonia can be supplied to the solid particle movement line that circulates to the combustion furnace 100, and combustibility can be improved through vaporization and preheating of the ammonia.

FIG. 4 is a graph showing the temperature in the combustion furnace 100 according to the ratio of the supply amounts of the first, second, and third oxidants in the circulating fluidized bed combustion system 1.

The second oxidizer is added together with the fuel to ensure smooth supply of fuel, and is supplied at a flow rate within a predetermined range to ensure smooth fuel supply.

In a multi-stage combustion system, the flow rate of the first oxidant is reduced and the third oxidant is used accordingly. Therefore, when the flow rate of the first oxidant is too small and the flow rate of the third oxidant is too high, the flow rate of the oxidant supplied to the lower part of the combustion furnace 100 is insufficient, and the solid material serving as a heat medium does not circulate smoothly. Therefore, the temperature of the lower part of the combustion furnace 100 may increase. In the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, the high temperature heat of the lower part of the combustion furnace 100 is used as a heat source for preheating and vaporization of ammonia. By using it, the limitation of the range of the supply ratio of the first oxidizing agent, the second oxidizing agent, and the third oxidizing agent can be alleviated, and the ammonia co-firing rate can be improved.

In the circulating fluidized bed combustion system (1) according to an embodiment of the present invention, the supply amount ratio (ratio of each flow rate) of the first oxidant, the second oxidant, and the third oxidant may be 65 to 80:5 to 15:10 to 25. there is.

In the circulating fluidized bed combustion system (1) according to an embodiment of the present invention, the fuel may be any one of biomass, coal, sludge, solidified fuel, or a mixture of two or more thereof.

The fuel may be either biomass or coal, and the coal may be bituminous coal.

The fuel may be made of one or more of biomass, sub-bituminous coal, and lignite.

In the circulating fluidized bed combustion system (1) according to an embodiment of the present invention, the effect of improving combustibility can be obtained through co-firing of low-grade coal such as biomass, sub-bituminous coal, and lignite with high volatile content and ammonia.

In addition, when fuel with a high volatile content is input into a combustion furnace, rapid devolatilization occurs, and ammonia can be burned using the heat released at this time.

When the fuel is biomass, the ratio of the height at which the tertiary oxidant supply part 230 is formed in the combustion furnace 100 (height of the third point P3) to the overall height of the combustion furnace 100 may be 0.7 to 0.9. there is. Specifically, it may be 0.75 to 0.85.

When the fuel is coal, the ratio of the height at which the tertiary oxidant supply part 230 is formed in the combustion furnace 100 (height of the third point P3) to the overall height of the combustion furnace 100 may be 0.5 to 0.75. . Specifically, it may be 0.6 to 0.7.

If the position (third point (P3)) where the tertiary oxidant supply unit 230 is formed is too high, the reduction area for converting NO to N2 increases, but the oxidation area decreases, so the residence time of the fuel in the oxidation area increases. As it becomes shorter, CO cannot be sufficiently oxidized to CO ₂ . Therefore, the amount of NO generation decreases and the amount of CO generation increases.

Conversely, if the position where the third oxidizing agent supply part is formed (third point P3) is too low, the reduction area decreases and the oxidation area increases, so the amount of CO generated decreases and the amount of NO generated increases.

The temperature distribution within the combustion furnace 100 is different depending on the ratio of the supply amounts of the first oxidizing agent, the second oxidizing agent, and the third oxidizing agent, and a graph of the temperature by height of the combustion furnace 100 according to this is shown in FIG. 4. It is shown.

In Figure 4, Example 1 (Run 1) is the result of operating at a supply ratio of the first, second, and third oxidants at 91%:9%:0% without using multi-stage combustion.

Example 2 (Run 2) and Example 3 (Run 3) are cases in which multi-stage combustion is used, and in this case, the height of the tertiary oxidant supply unit 230 in the combustion furnace 100 compared to the overall height of the combustion furnace 100 The ratio is 0.64. Specifically, the supply height of the third oxidizing agent is 6.4 m.

Example 2 (Run 2) is the result of operating at a supply ratio of the first oxidizing agent, second oxidizing agent, and third oxidizing agent at 82%:9%:9%, and Example 3 (Run 3) is the result of operating the first oxidizing agent, This is the result of operating at a supply ratio of the second oxidizing agent and the third oxidizing agent at 73%:9%:18%.

In this way, it can be seen that when the supply amount of the third oxidant is increased while reducing the supply amount of the first oxidant, the temperature at the bottom of the combustion furnace 100 increases, and ammonia has a relatively high autoignition temperature, making it suitable for use in a typical boiler. Although preheating of ammonia is required for application, in the circulating fluidized bed combustion system 1 according to an embodiment of the present invention, ammonia is supplied to the lower part of the combustion furnace 100, thereby dissipating the high temperature heat in the lower part of the combustion furnace 100. It can be used for preheating and combustion of ammonia and can form a circulating fluidized bed combustion system (1) with excellent ammonia co-combustion rate.

In addition, it is possible to reduce nitrogen oxides generated during ammonia combustion through multi-stage combustion, and the temperature of the lower part of the combustion furnace 100 can be controlled to prevent agglomeration of solid materials in the lower part of the combustion furnace 100. .

In addition, there is no need to install a separate vaporizer for ammonia vaporization, and if some of the steam generated during the process is used, a decrease in plant efficiency can be prevented.

The circulating fluidized bed combustion system 1 according to an embodiment of the present invention may include an exhaust gas purification unit 400.

The exhaust gas purification unit 400 is configured to purify the exhaust gas discharged from the combustion furnace 100.

The exhaust gas purification unit 400 includes a first heat exchanger 410, a bag-filter 420, a second heat exchanger 430, a condenser 440, a second blower 450, and a stack ( 460) (stack) may be included.

The first heat exchanger 410 is connected to the upper part of the second cyclone 312. The first heat exchanger 410 is configured to adjust the temperature of the exhaust gas introduced from the second cyclone 312 to a temperature appropriate for supplying it to the bag filter 420 through heat exchange. For example, in order to prevent the bag filter 420 from being damaged when the internal temperature of the bag filter 420 is higher than a predetermined temperature (e.g., 250°C or higher), the first heat exchanger 410 connects the exhaust gas and Heat exchange can be performed.

The bag filter 420 is connected to the lower part of the first heat exchanger 410 and is configured to remove dust generated in the combustion furnace 100. The bag filter 420 can separate dust in the exhaust gas that was not separated in the cyclone 312 and allow only the exhaust gas to be moved to a subsequent facility.

The second heat exchanger 430 is connected to the upper part of the bag filter 420 and adjusts the temperature of the exhaust gas introduced through the bag filter 420 to a temperature appropriate for supply to the condenser 440. For example, when the internal temperature of the condenser 440 is higher than a predetermined temperature (e.g., 100°C or higher), the second heat exchanger 430 exchanges heat with the exhaust gas to prevent the performance of the condenser 440 from deteriorating. can be performed.

The condenser 440 may be connected to the lower part of the second heat exchanger 430 and may be configured to collect moisture from the exhaust gas passing through the second heat exchanger 430. The condenser 440 can be configured to directly spray water to condense moisture in the exhaust gas or to absorb and remove SO2.

The second blower 450 is connected to the condenser 440 and supplies the exhaust gas discharged from the condenser 440 to the stack 460.

The stack 460 is connected to the second blower 450 and is configured to discharge the supplied exhaust gas to the outside.

In the circulating fluidized bed combustion system (1) according to an embodiment of the present invention, the production of NO by nitrogen substances in the fuel is suppressed and agglomeration, slagging, etc. of solid substances in the heat medium are prevented from occurring. do. In addition, as the temperature of the lower part of the combustion furnace 100 can be maintained, the heat absorption rate of the circulating fluidized bed can be maintained the same.

Although specific embodiments of the present invention have been described and shown above, the present invention is not limited to the described embodiments, and those skilled in the art can vary the invention to other specific embodiments without departing from the spirit and scope of the present invention. You will understand that it can be modified and transformed. Therefore, the scope of the present invention should not be determined by the described embodiments, but rather by the technical idea stated in the claims.

1: Circulating fluidized bed combustion system 100: Combustion furnace
201: air tank 202: first blower
210: primary oxidant supply unit 220: secondary oxidant supply unit
230: Tertiary oxidant supply unit 311: First cyclone
312: 2nd cyclone 320: Loop seal
330: Downcomer 400: Exhaust gas purification unit
410: first heat exchanger 420: bag filter
430: second heat exchanger 440: condenser
450: second blower 460: stack
510: first ammonia supply unit 520: second ammonia supply unit
P1: first point P2: second point
P3: Third point P4: Fourth point
P5: Fifth point

Claims (10)

A combustion furnace in which a combustion reaction occurs;
a primary oxidant supply unit connected to the combustion furnace at a first point and supplying a first oxidant;
a secondary oxidant supply unit connected to the combustion furnace at a second point higher than the first point and supplying a second oxidant and fuel;
a third oxidant supply unit connected to the combustion furnace at a third point higher than the second point and supplying a third oxidant; and
A first ammonia supply unit connected to the combustion furnace at a fourth point equal to or lower than the second point and configured to supply ammonia,
Circulating fluidized bed combustion system. According to paragraph 1,
The first ammonia supply unit is connected to the combustion furnace in the area where the heat medium stays,
Circulating fluidized bed combustion system. According to paragraph 1,
The circulating fluidized bed combustion system,
A cyclone connected to the upper side of the combustion furnace and configured to separate exhaust gas and solid particles discharged from the combustion furnace;
A loop seal through which solid particles separated from the cyclone are introduced;
A downcomer connecting the roof seal and the combustion furnace to allow the solid particles to move; and
Comprising a second ammonia supply unit connected to the downcomer and configured to supply ammonia,
Circulating fluidized bed combustion system. A combustion furnace in which a combustion reaction occurs;
A cyclone connected to the upper side of the combustion furnace and configured to separate exhaust gas and solid particles discharged from the combustion furnace;
A loop seal through which solid particles separated from the cyclone are introduced;
A downcomer connecting the roof seal and the combustion furnace to allow the solid particles to move;
a primary oxidant supply unit connected to the combustion furnace at a first point and supplying a first oxidant;
a secondary oxidant supply unit connected to the combustion furnace at a second point higher than the first point and supplying a second oxidant and fuel;
a third oxidant supply unit connected to the combustion furnace at a third point higher than the second point and supplying a third oxidant; and
Comprising a second ammonia supply unit connected to the downcomer and configured to supply ammonia,
Circulating fluidized bed combustion system. According to clause 3 or 4,
The downcomer is connected to the combustion furnace at a fifth point,
The fifth point is higher than the first point and lower than the second point,
Circulating fluidized bed combustion system. According to clause 3 or 4,
The cyclone is,
A first cyclone connected to the combustion furnace; and
A second cyclone connected to the first cyclone and configured to separate fly ash from the exhaust gas discharged from the first cyclone,
The loop seal is where solid particles separated from the first cyclone enter,
Circulating fluidized bed combustion system. According to any one of claims 1 to 3,
Ammonia is supplied in liquid form from the first ammonia supply unit,
Circulating fluidized bed combustion system. According to clause 4,
Ammonia is supplied in liquid form from the second ammonia supply unit,
Circulating fluidized bed combustion system. According to any one of claims 1 to 4,
The supply ratio of each of the first oxidizing agent, the second oxidizing agent, and the third oxidizing agent is 65 to 80:5 to 15:10 to 25,
Circulating fluidized bed combustion system. According to any one of claims 1 to 4,
The fuel is one or more of biomass, sub-bituminous coal, and lignite,
Circulating fluidized bed combustion system.

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