JP2020112280A - Boiler device and thermal power generation facility, capable of carrying out mixed combustion of ammonia - Google Patents

Abstract

To use ammonia (NH3) as a part of fuel, keeping nitrogen oxides (NOX) being discharged in a controlled condition, in a powdered-coal combustion boiler device and a thermal power generation facility.SOLUTION: Selecting a lower stage burner 3a, or the lower stage burner 3a and a middle stage burner 3b, excluding an upper stage burner 3c according to the ratio of ammonia (NH3) relative to total fuel, ammonia (NH3) is fed thereinto to control discharge of unburnt ammonia (NH3) and nitrous oxide (NO2) by securing a time for combusting ammonia (NH3), and to decompose nitrogen oxides by a reduction substance generated in all of the burners 3a to 3c.SELECTED DRAWING: Figure 1

Description

The present invention relates to a boiler device capable of co-firing ammonia, which can use ammonia (NH ₃ ) as a part of fuel.
The present invention relates to a thermal power generation facility having a boiler device capable of co-firing ammonia, which can use ammonia (NH ₃ ) as a part of fuel.

Various burners for combustion in a boiler apparatus for burning pulverized coal have been conventionally proposed (for example, Patent Document 1). Conventionally proposed combustion burners suppress the generation of nitrogen oxides (NO _x ) by devising the supply of fuel mixture consisting of pulverized coal and primary air, secondary air, two-stage combustion air, etc. I am making it.

On the other hand, the use of ammonia (NH ₃ ) as a transportation/storage medium (carrier) for hydrogen (H ₂ ) that is a fuel that does not emit carbon dioxide (CO ₂ ) is being studied, and a combustion device without conversion to H ₂ is used. If NH ₃ can be used directly as the fuel of ( ₃₎ , improvement of thermal efficiency can be expected as compared with the case of using after converting NH ₃ to H ₂ .

However, compared to H ₂ and other hydrocarbon fuels, NH ₃ is less likely to be ignited, has a slow burning rate, and has a problem that NO _X is generated in the burning process. Therefore, in developing a boiler apparatus using NH ₃ as a fuel, special control and special equipment for processing unburned NH ₃ , NO _X, etc. are required, which leads to an increase in equipment cost. There were challenges.

JP-A-5-240410

The present invention has been made in view of the above circumstances, and is a boiler device capable of co-firing ammonia, which can use ammonia (NH ₃ ) as a part of fuel while suppressing exhausted nitrogen oxides (NO _x ). The purpose is to provide.

Further, the present invention has been made in view of the above circumstances, and ammonia (NH ₃ ) that can use ammonia (NH ₃ ) as a part of the fuel while suppressing the discharged nitrogen oxides (NO _x ) can be mixed and burned. It is an object to provide a thermal power generation facility having a boiler device.

A boiler apparatus capable of co-firing ammonia of the present invention according to claim 1 for achieving the above object, is provided with a furnace body in which combustion gas flows, and pulverized coal together with a fluid containing oxygen, and the combustion gas in the furnace body. A plurality of burners are provided from the upstream side to the downstream side in the flow direction, and ammonia supply means for supplying ammonia to the burners other than the burner on the most downstream side are provided.

In the present invention according to claim 1, ammonia (NH ₃ ) can be supplied to a burner (upstream burner) excluding the burner on the most downstream side, and ammonia (NH ₃ ) can be used as a fuel.

When using ammonia (NH ₃ ) as fuel, unlike the invention of claim 1, when ammonia (NH ₃ ) is supplied to the burner on the most downstream side, ammonia and coal are decomposed by the flame of the burner and a part thereof is supplied. Are combined with oxygen to produce nitrogen oxides, and the produced nitrogen oxides (NOx) are reducing substances (NH ₃ , HCN) produced in the flames of the burner and the burners on the upstream side (all burners). Etc.) decomposes into nitrogen (N ₂ ) only in the flame of the burner on the most downstream side and only on the downstream side thereof.

On the other hand, in the invention of claim 1, when ammonia (NH ₃ ) is supplied to the burner excluding the burner on the most downstream side, the flame of the burner decomposes ammonia and coal, and part of them is combined with oxygen to form nitrogen. Oxides are produced, and the produced nitrogen oxides (NO _x ) are reduced by the reducing substances (NH ₃ , HCN, etc.) produced in the flames of all the burners including the burner and the burner on the downstream side thereof. And the time it takes to decompose nitrogen oxides (NO _x ) in the flame of the burner on the downstream side and on the downstream side of the burner is secured longer than when ammonia (NH ₃ ) is supplied to the burner on the most downstream side. Are decomposed into nitrogen (N ₂ ).

Therefore, it becomes possible to use ammonia (NH ₃ ) as a part of the fuel while suppressing the nitrogen oxides (NO _x ) that are discharged.

And the boiler apparatus capable of co-firing ammonia according to the present invention according to claim 2 is the boiler apparatus capable of co-firing ammonia according to claim 1, wherein the burner provided with the ammonia supply means has at least the burner on the most upstream side. It is characterized by including.

In the present invention according to claim 2, ammonia (NH ₃ ) can be supplied to at least the most upstream burner to use the ammonia (NH ₃ ) as a fuel.

Further, the boiler apparatus capable of co-firing ammonia according to the present invention according to claim 3 is the boiler apparatus capable of co-firing ammonia according to claim 1 or 2, wherein the ammonia supply means adjusts the ratio of the ammonia to the total fuel. Based on the above, it has a function of selecting the burner for supplying ammonia.

In the present invention according to claim 3, the burner excluding the burner on the most downstream side, for example, the most upstream side burner, or the most upstream side burner and the middle stage, is used according to the ratio of ammonia (NH ₃ ) to the total fuel. The burner can be selected to supply ammonia.

Further, the boiler apparatus capable of co-firing ammonia according to the present invention according to claim 4 is the boiler apparatus capable of co-firing ammonia according to any one of claims 1 to 3, wherein the burner has a flow of the combustion gas. 3 sets are provided from the upstream side to the downstream side in the direction, and the ammonia supply means selects the most upstream burner or the most upstream and adjacent central burner based on the ratio of the ammonia to the total fuel. Characterize.

In the present invention according to claim 4, ammonia (NH ₃ ) can be supplied from the most upstream burner or the most upstream and central burners based on the proportion of ammonia (NH ₃ ).

Further, the boiler apparatus capable of co-firing ammonia according to the present invention according to claim 5 is the boiler apparatus capable of co-firing ammonia according to any one of claims 1 to 4, wherein the ammonia supply means is for all fuels. The ratio of the ammonia is adjusted to less than 50% of the calorific value of all fuels.

In the present invention according to claim 5, the ratio of ammonia (NH ₃ ) to the total fuel is adjusted to be less than 50% of the calorific value of the total fuel, so that the concentration of nitrogen oxides (NO _x ) does not become too high. (NH ₃ ) can be used as part of the fuel (without being the main fuel). The proportion of ammonia (NH ₃ ) is more preferably 25% or less (particularly 20% or less) of the calorific value of all fuels.

A thermal power plant of the present invention according to claim 6 for achieving the above object is a boiler device capable of co-firing ammonia according to any one of claims 1 to 5, and a boiler device capable of co-firing the ammonia. A steam turbine that obtains a driving force by the steam generated in 1. and a power generation unit that obtains a power generation power by driving the steam turbine.

In the present invention according to claim 6, thermal power generation having a boiler device capable of co-firing ammonia, which can use ammonia (NH ₃ ) as a part of fuel in a state in which exhausted nitrogen oxides (NO _x ) are suppressed. It becomes possible to be equipment.

The boiler apparatus capable of co-firing ammonia according to the present invention can use ammonia (NH ₃ ) as a part of fuel in a state where exhausted nitrogen oxides (NO _x ) are suppressed.

Further, the thermal power generation facility of the present invention has a boiler having a boiler device capable of cofiring ammonia, which can use ammonia (NH ₃ ) as a part of fuel in a state in which exhausted nitrogen oxides (NO _x ) are suppressed. It can be used as a power generation facility.

It is a schematic diagram showing the whole composition of thermal power generation equipment which has a boiler device which can co-fire ammonia concerning one example of the present invention. It is a structure explanatory view of a burner. Nitrogen oxides (NO _X) and the concentration of ammonia (NH ₃₎ is a graph showing the relationship between the burner supplies. Nitrogen oxides (NO _X) and the concentration of ammonia (NH ₃₎ is a graph showing the relationship between the burner supplies.

The entire boiler apparatus capable of co-firing ammonia will be described with reference to FIG.
FIG. 1 shows an overall configuration of a thermal power plant having a boiler device capable of co-firing ammonia according to an embodiment of the present invention.

As shown in the figure, the boiler device 1 (boiler device capable of co-firing ammonia) includes a furnace body having a combustion chamber 2 in which combustion gas flows from bottom to top. The combustion chamber 2 is provided with three sets of burners 3 from the upstream side (lower side) to the downstream side (upper side) in the gas flow direction. That is, the lower burner 3a on the upstream side, the middle burner 3b, and the upper burner 3c on the downstream side are provided. Pulverized coal is supplied from the coal supply means 4 to the burner 3 together with a fluid (air) containing oxygen (O ₂ ). The fluid (air) containing oxygen (O ₂ ) is also supplied to the two-stage combustion air injection port 5.

Except for the upper burner 3c, the lower burner 3a, or the lower burner 3a and the middle burner 3b (burners excluding the most downstream burner: at least the lowermost burner 3a on the most upstream side) has ammonia (NH ₃ ) Is provided for supplying ammonia. The ammonia supply unit 6 has a function of selecting the burners 3a and 3b that supply ammonia based on the ratio of ammonia (NH ₃ ) to the total fuel (for example, 20% or less), that is, the distribution control unit 7. There is.

When ammonia (NH ₃ ) is evenly supplied to the bottom burner 3a, the middle burner 3b, and the upper burner 3c, the ammonia (NH ₃ ) ratio to the total fuel is, for example, 6.7%, 13. 3%, in the case of 20%, compared to the time of combustion of only coal, according ammonia (NH ₃₎ ratio is high, the concentration of nitrogen oxides boiler outlet (NO _X) has been confirmed to be elevated.

Therefore, in the boiler device 1 according to the present embodiment, ammonia (NH ₃ ) is supplied to at least the lowermost stage (upstreammost side) burner 3 (lowermost stage burner 3a). For example, according to the ratio of ammonia (NH ₃ ) to the total fuel, the burner 3 excluding the upper burner 3c, that is, the lower burner 3a, or the lower burner 3a and the middle burner 3b is selected and the ammonia is selected. (NH ₃ ) is being supplied.

By supplying ammonia (NH ₃ ) to at least the lowermost burner 3 (lowermost burner 3a), even if ammonia (NH ₃ ) is used as a fuel, the generated nitrogen oxides (NO _X ) is the unburned ammonia (NH ₃ ) from the burner 3a and the reducing substances (NH ₃ , HCN, etc.) produced in the flames of all the burners 3a to 3c, and in the flames of all the burners 3a to 3c and It reacts downstream, ensuring longer reaction times and reducing nitrogen oxides (NO _x ) and unburned ammonia (NH ₃ ). Further, the generated nitrous oxide (N ₂ O) also reacts in the high temperature flames of all the burners 3a to 3c and the downstream side thereof, and the decomposition time is secured longer and reduced.

Therefore, it is possible to use ammonia (NH ₃ ) as a part of the fuel in a state where the discharged nitrogen oxides (NO _x ) are suppressed.

By the way, when ammonia (NH ₃ ) is supplied to the burner 3c at the uppermost stage (downstream side), the flame of the burner 3c decomposes ammonia and coal, and at the same time, a part of them is combined with oxygen to generate nitrogen oxides. The generated nitrogen oxides (NOx) are generated in the flames of the burner and the lower (upstream) burners 3a and 3b (all burners) of the burner, and the reducing substances (NH ₃ , HCN, etc.) generate the uppermost stage. It is decomposed into nitrogen (N ₂ ) only in the flame of the burner 3c (the most downstream side) and its downstream side. That is, compared with the case where ammonia (NH ₃ ) is supplied to the burner 3a in the lowermost stage (upstreammost side), the time required for the generated nitrogen oxides (NOx) to decompose into nitrogen (N ₂ ) becomes shorter, and the boiler is reduced. Nitrogen oxide (NOx) at the outlet increases.

Steam is generated by burning coal and ammonia (NH ₃ ) as fuel in the boiler device 1. The steam generated in the boiler device 1 is sent to the steam turbine 8, and the steam turbine 8 drives a generator (power generation means) 9. The exhaust steam that has finished its work in the steam turbine 8 is condensed and supplied to the boiler device 1. The exhaust gas of the boiler device 1 has impurities removed by the smoke treatment means 10 and is released to the atmosphere.

The burner 3 will be specifically described with reference to FIG.
FIG. 2 shows a schematic structure of the burner 3 (the lower burner 3a and the middle burner 3b).

The burner 3 (the lower burner 3a and the middle burner 3b) is provided with a primary air introducing pipe 11, a secondary air introducing port 12, and a tertiary air introducing port 13, and the primary air introducing pipe 11 has coal (pulverized coal). The introduction path 14 of is connected. Further, the burner 3 is provided with a heavy oil torch 15 for ignition. The primary air introduction pipe 11 has a double structure, and primary air and pulverized coal are supplied to the outer pipe 11a. Distribution control means 7 (see FIG. 1) is connected to the inner pipe 11b so that ammonia (NH ₃ ) is supplied.

The pulverized coal supplied together with the primary air from the introduction passage 14 is injected into the combustion chamber 2 from the pipe 11a outside the primary air introduction pipe 11. The pulverized coal sent to the combustion chamber 2 burns together with the primary air and the secondary air and the tertiary air that are sent as a swirling flow from the secondary air introduction port 12 and the tertiary air introduction port 13. At the same time, a predetermined amount of ammonia (NH ₃ ) is supplied from the pipe 11b inside the primary air introducing pipe 11, and ammonia (NH ₃ ) is injected into the combustion chamber 2 and burned.

The state of the concentration of nitrogen oxides (NO _x ) will be described based on FIGS. 3 and 4.

FIG. 3 illustrates the situation of the concentration of nitrogen oxides (NO _x ) at the supply position when a predetermined amount (for example, 6.7% of the total fuel) of ammonia (NH ₃ ) is supplied as fuel. A graph, FIG. 4, shows the situation of the concentration of nitrogen oxides (NO _x ) at the supply position when a predetermined amount (for example, 13.3% of the calorific value of all fuels) of ammonia (NH ₃ ) is supplied as fuel. The graph to explain is shown.

As shown in FIG. 3, when only coal is burned (coal combustion), the concentration of nitrogen oxides (NO _x ) at the boiler outlet is, for example, about 130 ppm, and for example, the calorific value of all fuels is 6.7. % When ammonia (NH ₃ ) is supplied as a fuel, when the ammonia (NH ₃ ) is evenly supplied from all _three burners 3 (all stages), the concentration of nitrogen oxides (NO _x ) at the boiler outlet is increased. Is, for example, about 150 ppm.

When ammonia (NH ₃ ) is supplied only from the burner 3c at the uppermost stage (downstream side) (only at the upper stage), the concentration of nitrogen oxides (NO _x ) at the boiler outlet is, for example, about 180 ppm. ing. Furthermore, when ammonia (NH ₃ ) is supplied only from the middle-stage burner 3b (only in the middle stage), the concentration of nitrogen oxides (NO _x ) at the boiler outlet is, for example, about 160 ppm.

On the other hand, when ammonia (NH ₃ ) is supplied only from the burner 3a in the lowermost stage (upstreammost side) (only in the lower stage), the concentration of nitrogen oxides (NO _x ) at the boiler outlet is, for example, about 130 ppm. Has become. This is approximately the same as the concentration of nitrogen oxides (NO _x ) when only coal is burned (coal burning), and when ammonia (NH ₃ ) is evenly supplied from all _three burners 3 (all stages). Is also low.

As can be seen from FIG. 3, for example, the case of supplying 6.7% ammonia in heating value of the total fuel (NH ₃₎ as a fuel, ammonia only from the burner 3a of the bottom (most upstream side) (NH ₃₎ By supplying, the concentration of nitrogen oxides (NO _x ) at the boiler outlet is suppressed.

For example, it has been confirmed that the concentration of nitrous oxide (N ₂ O) is suppressed when ammonia (NH ₃ ) of 6.7% of the calorific value of all fuels is supplied as fuel. It has been confirmed that unburned ammonia (NH ₃ ) is not produced.

Therefore, for example, in the case of supplying 6.7% of the calorific value of all fuels as ammonia (NH ₃ ) as a fuel, by supplying ammonia (NH ₃ ) only from the burner 3a at the lowermost stage (upstream side), Generation of nitrogen oxides (NO _x , N ₂ O) is suppressed, and emission of unburned ammonia (NH ₃ ) is suppressed.

As shown in FIG. 4, when only coal is burned (coal combustion), the concentration of nitrogen oxides (NO _x ) at the outlet is, for example, about 130 ppm, which is, for example, 13.3% of the calorific value of all fuels. When supplying ammonia (NH ₃ ) as a fuel, when the ammonia (NH ₃ ) is evenly supplied from all _three burners 3 (all stages), the concentration of nitrogen oxide (NO _x ) at the outlet is For example, it is about 220 ppm.

Further, when ammonia (NH ₃ ) is supplied from the upper burner 3c and the intermediate burner 3b (upper and middle stages), the concentration of the nitrogen oxide (NO _x ) at the outlet is, for example, about 250 ppm. ing.

On the other hand, when ammonia (NH ₃ ) was supplied from the lower burner 3a and the middle burner 3b excluding the upper burner 3c (middle/lower), nitrogen oxide (NO _x ) at the outlet Is about 200 ppm, for example. This is a lower concentration than when ammonia (NH ₃ ) is uniformly supplied from the _three burners 3 (all stages).

When additionally installing a pipe 11b for supplying ammonia to the primary air introduction pipe 11 of the existing burner, if the pipe 11b is provided only for one burner and the supply rate of ammonia is increased too much, the basic performance of the existing burner will be increased. May change and the burner design may need to be changed. Therefore, as can be seen from FIG. 4, for example, when supplying 13.3% of the calorific value of all fuels as ammonia (NH ₃ ) as a fuel, the primary air introduction pipes of the lower burner 3 a and the middle burner 3 b 11 is additionally provided with a pipe 11b for supplying ammonia, and ammonia (NH ₃ ) is supplied from the lower burner 3a and the middle burner 3b to suppress the ammonia supply ratio of each stage burner. Therefore, ammonia can be supplied while maintaining the basic performance of the existing burner.

For example, it has been confirmed that the concentration of nitrous oxide (N ₂ O) is suppressed when ammonia (NH ₃ ) of 13.3% of the calorific value of all fuels is supplied as fuel. It has been confirmed that unburned ammonia (NH ₃ ) is not produced.

Therefore, for example, when supplying ammonia (NH ₃ ) of 13.3% of the calorific value of all fuels as a fuel, ammonia (NH ₃ ) is removed from the lower burner 3a and the intermediate burner 3b excluding the upper burner 3c. ₃₎ by supplying nitrogen oxides _{(NO X, N} 2 O) generated is suppressed and discharge of unburned ammonia (NH ₃₎ is suppressed.

In addition, it is preferable to adjust the ratio of ammonia (NH ₃ ) to the total fuel to less than 50% of the calorific value of the total fuel. By adjusting the proportion of ammonia (NH ₃ ) to less than 50% of the calorific value of all fuels, the production of nitrogen oxides (NO _X , N ₂ O) is suppressed, and the unburned ammonia (NH ₃ ) is discharged. Has been confirmed to be suppressed. As a result, ammonia (NH ₃ ) can be used as a part of the fuel (not as the main fuel) without increasing the concentration of nitrogen oxide (NO _x ) too much. The proportion of ammonia (NH ₃ ) is more preferably 25% or less (particularly 20% or less) of heat generation of all fuels.

Incidentally, when the ratio of ammonia (NH ₃ ) to all fuels is set to 50% or more of the calorific value of all fuels, when ammonia (NH ₃ ) is supplied to the burners other than the burner at the uppermost stage (downstream side), The proportion of ammonia in the fuel supplied to the burner will increase significantly, the basic performance of the existing burner will change, and it will not be possible to deal with small modifications of the burner, and major modifications such as new installation of a dedicated burner will not be possible. It may be necessary and the cost of remodeling may increase.

On the other hand, by adjusting the ratio of ammonia (NH ₃ ) to all fuels to less than 50% of the calorific value of all fuels, ammonia (NH ₃ ) can be used as a part of fuel by a minor modification of the existing burner. By using (not as the main fuel), it becomes possible to suppress the emission of nitrogen oxides (NO _x , N ₂ O) and unburned ammonia (NH ₃ ).

The boiler device 1 supplies ammonia (NH ₃ ) to the lowermost burner 3a, or the lowermost burner 3a and the middle burner 3b, so that the generation of nitrogen oxides (NO _X , N ₂ O) is not generated. in a state of discharging the suppression of combustion of ammonia (NH _3), comprising ammonia (NH ₃₎ it can be used as part of the fuel. Further, the boiler device 1 is capable of using ammonia (NH ₃ ) as a part of fuel in a state in which generation of nitrogen oxides (NO _X , N ₂ O) and discharge of unburned ammonia (NH ₃ ) are suppressed. It becomes possible to make it the thermal power generation equipment which has.

The present invention, ammonia (NH ₃₎ boiler apparatus capable of mixed combustion of ammonia that can be used as part of the fuel, and can be utilized in the industrial fields of thermal power plants having a boiler apparatus.

DESCRIPTION OF SYMBOLS 1 Boiler apparatus 2 Combustion chamber 3 Burner 4 Coal supply means 5 Two-stage combustion air injection port 6 Ammonia supply means 7 Distribution control means 8 Steam turbine 9 Generator 10 Smoke treatment means 11 Primary air inlet pipe 12 Secondary air inlet 13 Tertiary Air Inlet 14 Inlet 15 Heavy Oil Torch

Claims (6)

A furnace body through which combustion gas flows,
Pulverized coal is supplied together with a fluid containing oxygen, and a plurality of burners provided from the upstream side to the downstream side in the flow direction of the combustion gas in the furnace body,
A boiler apparatus capable of co-firing ammonia, comprising: ammonia supply means for supplying ammonia to the burners other than the burner on the most downstream side. A boiler apparatus capable of co-firing ammonia according to claim 1,
The boiler device capable of co-firing ammonia, wherein the burner provided with the ammonia supply means includes at least a burner on the most upstream side. A boiler device capable of co-firing ammonia according to claim 1 or 2,
The ammonia supply means,
A boiler apparatus capable of co-firing ammonia, having a function of selecting the burner for supplying ammonia based on the ratio of the ammonia to all fuels. A boiler apparatus capable of co-firing ammonia according to any one of claims 1 to 3,
The burner is
Three sets are provided from the upstream side to the downstream side in the flow direction of the combustion gas,
The ammonia supply means,
A boiler apparatus capable of co-firing ammonia, characterized in that the most upstream burner or the most upstream and adjacent central burner is selected based on the ratio of the ammonia to the total fuel. The boiler device according to any one of claims 1 to 4,
The ammonia supply means,
A boiler device capable of co-firing ammonia, characterized in that the ratio of the ammonia to the total fuel is adjusted to less than 50% of the calorific value of the total fuel. A boiler device capable of co-firing ammonia according to any one of claims 1 to 5,
A steam turbine that obtains a driving force by the steam generated in the boiler device,
A thermal power generation facility comprising: a power generation unit that obtains power generation power by driving the steam turbine.

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