Oxygen carrier reinforced ammonia-doped carbon-reducing combustion system and method for circulating fluidized bed boiler

Abstract

The invention relates to the field of low-carbon combustion of circulating fluidized bed boilers, in particular to an oxygen carrier reinforced ammonia-doped carbon-reducing combustion system and method for a circulating fluidized bed boiler, ammonia gas and combustion-supporting air are introduced into a hearth with pulverized coal and an oxygen carrier, the oxygen carrier circulates in the hearth in a reciprocating mode under the action of the combustion-supporting air and the gravity of the oxygen carrier, and in a dense-phase bed layer in the hearth, the combustion-supporting air and the oxygen carrier are mixed in the hearth. The oxygen carrier in the oxidation state uses combined oxygen of the oxygen carrier in the oxidation state for oxidation of ammonia and is partially converted into the oxygen carrier in the reduction state, the oxygen carrier in the reduction state catalyzes and decomposes the ammonia to generate hydrogen, and meanwhile NOx emission is controlled; in the dilute-phase bed layer in the hearth, the oxygen carrier in the oxidation state catalyzes and oxidizes ammonia to promote combustion of the ammonia-coal fuel, the internal oxygen distribution condition of the circulating fluidized bed boiler can be improved, and the combustion efficiency of the ammonia-coal fuel in the ammonia-doped combustion circulating fluidized bed boiler is improved.

Description

Technical Field

[0001] The present invention relates to the field of low-carbon combustion of circulating fluidized bed boilers, and specifically to an oxygen carrier-enhanced circulating fluidized bed boiler ammonia-doping carbon reduction combustion system and method. Background Art

[0003] In order to improve the utilization rate of coal, a number of patents such as those with publication numbers CN101012929A, CN113280329A, CN112303634A, and CN111911934A have carried out research on oxygen carrier-assisted combustion technology for coal-fired boilers, waste incinerators, and waste rotary kiln furnaces; the Chinese invention patent with publication number 201910316488.1 discloses a fluidized bed oxygen carrier-assisted oxy-fuel combustion system and method. This fluidized bed oxygen carrier-assisted oxy-fuel combustion system and method uses an oxygen carrier as bed material and regulates coal combustion by the way of the oxygen carrier carrying and releasing oxygen, improves the uniformity of heat distribution in the furnace, ensures the stable operation of the equipment, and overcomes the difficult problems such as uneven oxygen distribution in the existing fluidized bed oxy-fuel combustion. This invention uses an oxygen carrier as bed material and regulates coal combustion by the way of the oxygen carrier carrying and releasing oxygen, improves the uniformity of heat distribution in the furnace, and ensures the stable operation of the equipment to overcome the difficult problems such as uneven oxygen distribution in the existing fluidized bed oxy-fuel combustion. Although this method improves the combustion efficiency of coal to a certain extent, since the combustion raw material is single coal, the pollution generated by coal still exists.

[0004] To promote the carbon emission reduction transformation of coal-fired boilers, there are also ways in the prior art to introduce other gases into coal for auxiliary combustion. For example, the Chinese invention patent with publication number CN216307787U discloses a coal-fired boiler biogas co-firing coupling combustion device. When this device uses biogas mainly composed of methane as fuel to co-fire with coal, it can greatly reduce the greenhouse effect. The co-firing of biogas can correspondingly reduce the coal consumption, not only reducing the cost of fuel coal, but also promoting the burnout of coal, thus achieving an energy-saving effect and realizing the low-cost, low-pollution, and energy-saving operation of the circulating fluidized bed boiler.

[0005] However, the solutions that can promote the carbon emission reduction transformation of coal-fired boilers are not limited to introducing biogas into the boiler. Ammonia, as a stable, carbon-free, and hydrogen-rich substance, is an important development direction of the hydrogen energy industry. The present invention provides a circulating fluidized bed boiler ammonia-doping carbon reduction combustion system and method. Summary of the Invention

[0006] The present invention aims to provide an oxygen carrier-enhanced circulating fluidized bed boiler ammonia-doping carbon reduction combustion system and method to improve the oxygen distribution inside the circulating fluidized bed boiler and increase the combustion efficiency of ammonia-coal fuel in the ammonia-doping combustion circulating fluidized bed boiler.

[0007] To solve the above technical problems, the specific solution adopted by the present invention is as follows: A method for oxycarrier-enhanced circulating fluidized bed boiler ammonia-doped and carbon-reduced combustion, in which ammonia gas and combustion-supporting air are introduced into the furnace with pulverized coal and oxycarrier. The oxycarrier reciprocally circulates in the furnace under the action of the combustion-supporting air and its own gravity. In the dense-phase bed layer in the furnace, the oxidized oxycarrier uses its combined oxygen for the oxidation of ammonia and is partially converted into the reduced state. The reduced oxycarrier catalytically decomposes ammonia to produce hydrogen, and at the same time controls NOx emissions; in the dilute-phase bed layer in the furnace, the oxidized oxycarrier catalytically oxidizes ammonia to promote the combustion of ammonia-coal fuel.

[0008] As a further optimization of the above technical solution: The combustion-supporting air includes primary air and secondary air, and the primary air inlet is located below the secondary air inlet.

[0009] An oxycarrier-enhanced circulating fluidized bed boiler ammonia-doped and carbon-reduced combustion system, based on the above-mentioned oxycarrier-enhanced circulating fluidized bed boiler ammonia-doped and carbon-reduced combustion method, includes a furnace. A wind chamber is provided at the bottom of the furnace, a primary air inlet is opened on the wind chamber, a secondary air inlet is opened on the side wall of the furnace, and a flue gas outlet is provided at the upper part of the furnace.

[0010] As a further optimization of the above technical solution: An ammonia gas inlet is also opened on the furnace, and the ammonia gas inlet is located between the primary air inlet and the secondary air inlet.

[0011] As a further optimization of the above technical solution: The primary air inlet is connected to an ammonia gas source.

[0012] As a further optimization of the above technical solution: The amount of oxycarrier used in the furnace is 10% - 100% of the bed material amount, and the balance is solid bed material.

[0013] As a further optimization of the above technical solution: The amount of oxycarrier used is 40% - 80% of the bed material amount.

[0014] As a further optimization of the above technical solution: The oxycarrier material is a natural ore or artificial synthetic material containing active components, including non-noble metal components and / or noble metal components.

[0015] As a further optimization of the above technical solution: The oxycarrier is a smooth spherical shape with a particle size of 100μm - 500μm. In the reduced state, the catalytic decomposition conversion rate of the oxycarrier to ammonia is 20% - 90%.

[0016] As a further optimization of the above technical solution: It also includes a cyclone device and a return device. A flue gas outlet is provided at the upper part of the furnace, and the flue gas outlet is connected to the feed inlet of the cyclone device through a pipeline; a separated gas outlet is provided at the top of the cyclone device, and a separated solid outlet connected to the return device is provided at the bottom. The discharge outlet of the return device is connected to the side wall of the furnace.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The oxycarrier-enhanced circulating fluidized bed boiler ammonia-doping carbon reduction system and method provided by the present invention can not only provide a feasible way for the clean transformation of power supply and heating in the industrial sector, but also save equipment construction and transformation costs, and provide a more reliable option for the industrial application of hydrogen / ammonia energy.

[0019] As a stable, carbon-free, and hydrogen-rich substance, ammonia is used as a fuel to replace part of the coal to promote carbon emission reduction in coal-fired boilers, reduce the consumption of coal, and thus reduce the pollution generated by coal combustion. However, due to the defects of ammonia itself, such as slow flame propagation speed and high ignition point, its combustion process in the circulating fluidized bed boiler is greatly affected by the ambient atmosphere. When the oxygen content in the environment is low (dense phase bed), the fuel ammonia is difficult to burn fully, which not only affects the fuel efficiency but also causes environmental problems such as ammonia escape; while under a higher ambient oxygen content (dilute phase bed), the uneven spatial and temporal distribution of oxygen will lead to the formation of local high temperatures in the furnace and may cause excessive oxidation of NH3, resulting in excessive NOx emissions and increasing the burden on the subsequent denitration unit.

[0020] In the present invention, this method uses an oxycarrier to partially or completely replace the circulating fluidized bed bed material. Utilizing the characteristics of the oxycarrier to absorb oxygen and become oxidized in the oxygen-rich area and release oxygen and convert to the reduced state in the oxygen-poor area, it has different beneficial effects on the combustion of fuel ammonia in the reduction combustion area and the oxidation combustion area. Based on the conventional ammonia-doping combustion state of the circulating fluidized bed boiler, in the reduction combustion area, the oxidized oxycarrier can use its bound oxygen for the oxidation of ammonia and partially convert to the reduced state. The reduced oxycarrier can play a certain catalytic decomposition role on ammonia, generating hydrogen that is easier to burn to promote fuel burnout; in the oxidation combustion area, the oxidized oxycarrier can play a catalytic oxidation role on ammonia, further promoting the oxidation of ammonia. The technical method provided in this case, through the replacement of the oxycarrier in the furnace bed material, on the one hand, can, relying on its own oxygen absorption-release characteristics, realize the regulation of the oxygen distribution in the furnace, promote combustion while controlling local overheating, and reduce the generation of thermal NOx; on the other hand, the active metal components in the oxycarrier can catalytically decompose a part of ammonia into nitrogen and hydrogen in the reducing atmosphere of the dense phase bed, promoting fuel burnout; at the same time, the oxycarrier itself can play a catalytic oxidation role on ammonia gas, effectively improving the fuel efficiency under the condition of ammonia-doping operation of the circulating fluidized bed boiler. Therefore, the development of the ammonia-doping carbon reduction technology for circulating fluidized bed boilers is of great significance for the carbon reduction transformation in the industrial field of our country. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the present invention.

[0022] Reference numerals: 1, air chamber; 2, furnace; 3, solid feeding system; 4, cyclone separator; 5, return device; 6, separated gas outlet; 7, primary air inlet; 8, secondary air inlet; I, primary air; II, secondary air; Ⅲ, pulverized coal; Ⅳ, bed material; Ⅴ, oxygen carrier; Ⅵ, separated gas. Detailed implementation manners

[0023] The technical solution of the present invention will be further elaborated in detail below in conjunction with the accompanying drawings and specific embodiments. For the parts not detailedly recorded and disclosed in the following embodiments of the present invention, they should all be understood as the prior art known or should be known to those skilled in the art.

[0024] Embodiment 1

[0025] This embodiment discloses a method for ammonia-doping and carbon-reducing combustion of an oxygen carrier-enhanced circulating fluidized bed boiler. As Figure 1 shown, ammonia gas and combustion-supporting air are introduced into the furnace 2 with pulverized coal Ⅲ and oxygen carrier Ⅴ. The oxygen carrier Ⅴ reciprocally circulates in the furnace 2 under the action of the combustion-supporting air and its own gravity. In the dense-phase bed layer in the furnace 2, the oxidized oxygen carrier Ⅴ uses its combined oxygen for the oxidation of ammonia and is partially converted into the reduced state. The reduced oxygen carrier Ⅴ catalytically decomposes ammonia to produce hydrogen, and at the same time controls the NOx emission; in the dilute-phase bed layer in the furnace 2, the oxidized oxygen carrier Ⅴ catalytically oxidizes ammonia to promote the combustion of ammonia-coal fuel.

[0026] The combustion-supporting air includes primary air I and secondary air II, and the primary air inlet 7 is located below the secondary air inlet 8. Ammonia gas can enter the furnace 2 through the ammonia gas inlet between the primary air I and the secondary air II, or ammonia gas can be introduced into the furnace 2 through the primary air inlet 7 along with the primary air I.

[0027] In the prior art, a solid bed material Ⅳ is provided in the furnace 2 of the circulating fluidized bed. In this method, the oxygen carrier Ⅴ is used to partially or completely replace the solid bed material Ⅳ of the circulating fluidized bed.

[0028] During the process of adding pulverized coal to the furnace 2 for combustion, through the combined use of the primary air I and the secondary air II, the oxygen carrier Ⅴ is urged to surge in the furnace 2 under the action of the primary air I, the secondary air II and the gravity of the oxygen carrier Ⅴ itself. Utilizing the characteristics that the oxygen carrier Ⅴ absorbs oxygen and becomes oxidized in the oxygen-rich area and releases oxygen and is converted into the reduced state in the oxygen-poor area, different enhancement effects are achieved on the combustion of fuel ammonia in the reducing combustion area and the oxidizing combustion area.

[0029] On the basis of the conventional ammonia - doped combustion state of a circulating fluidized bed boiler, in the reduction combustion zone, the oxygen - carrying agent V in the oxidized state can use its combined oxygen for the oxidation of ammonia and be partially converted into the reduced state. The reduced - state oxygen - carrying agent V can play a certain catalytic decomposition role on ammonia, generating hydrogen that is easier to burn to promote the complete combustion of fuel; in the oxidation combustion zone, the oxidized - state oxygen - carrying agent V can play a catalytic oxidation role on ammonia, further promoting the oxidation of ammonia.

[0030] The technical method provided by the present invention replaces the solid bed material IV in the furnace with the oxygen - carrying agent V. On the one hand, it can regulate the oxygen distribution in the furnace by virtue of its oxygen absorption - release characteristics, promote combustion while controlling local overheating, and reduce the generation of thermal - type NOx; on the other hand, the active metal components in the oxygen - carrying agent V can catalytically decompose a part of ammonia into nitrogen and hydrogen in the reducing atmosphere of the dense phase bed, promoting the complete combustion of fuel; at the same time, the oxygen - carrying agent V itself can play a catalytic oxidation role on ammonia, effectively improving the fuel efficiency under the ammonia - doped operation conditions of the circulating fluidized bed boiler.

[0031] The oxygen absorption - release reaction principle of the oxygen - carrying agent V in the present invention is as follows: 2Me x O y-1 +O2=2Me x O y (1) 2NH3+3Me x O y =Me x O y-1 +N2+3H2O (2) C i H j +(2i + 05j)Me x O y =(2i + 05j)Me x O y-1 +i CO2+0.5j H2O (3)

[0032] The ammonia catalytic decomposition reaction principle of the oxygen - carrying agent V in the present invention is as follows: 2NH3=N2+3H1 (4)

[0033] Generally speaking, a method for ammonia - doped carbon reduction in a circulating fluidized bed boiler strengthened by an oxygen - carrying agent V provided by the present invention can not only provide a feasible way for the clean transformation of power supply and heat supply in the industrial sector, but also save equipment construction and transformation costs, providing a more reliable choice for the industrial application of hydrogen / ammonia energy.

[0034] Example 2

[0035] Such as Figure 1As shown, this embodiment discloses an oxygen carrier-enhanced circulating fluidized bed boiler ammonia-blended carbon reduction combustion system, and this combustion system can adopt the oxygen carrier-enhanced circulating fluidized bed boiler ammonia-blended carbon reduction combustion method in Embodiment 1.

[0036] This combustion system includes a furnace 2, and an air chamber 1 is arranged at the bottom of the furnace 2. The furnace 2 is cylindrical, and the air chamber 1 is a conical shape with a larger upper part and a smaller lower part. The large-diameter end of the air chamber 1 has the same diameter as the cylindrical furnace 2.

[0037] A primary air inlet 7 is opened on the air chamber 1, and a secondary air inlet 8 is opened on the side wall of the furnace 2, and the secondary air inlet 8 is located at a position slightly lower than the middle of the side wall of the furnace 2. The primary air I introduced through the primary air inlet 7 and the secondary air II introduced through the secondary air inlet 8 are both air introduced into the furnace 2 to assist the combustion of the materials in the furnace 2, that is, both the primary air I and the secondary air II are combustion-supporting air.

[0038] A flue gas outlet is arranged at the upper part of the furnace 2, and the flue gas generated after the materials in the furnace 2 are combusted can be discharged from the flue gas outlet.

[0039] In the prior art, a fixed bed material IV is added into the furnace 2, and in order to maintain the normal use effect, the addition amount of the solid bed material IV needs to be maintained within a certain range, and the total amount of the solid bed material IV added when maintaining the normal use effect is set as the bed material amount.

[0040] In this embodiment, an oxygen carrier V is added into the furnace 2, and the addition amount of the oxygen carrier V is 10% - 100% of the bed material amount, and the balance is the solid bed material IV. That is, part or all of the solid bed material IV in the furnace 2 is replaced by the oxygen carrier V. When the usage amount of the oxygen carrier V is 100% of the bed material amount, no solid bed material IV is added into the furnace 2. When the usage amount of the oxygen carrier V is less than 100% of the bed material amount, the other materials except the oxygen carrier V are continuously supplemented with the original solid bed material IV.

[0041] Preferably, the usage amount of the oxygen carrier V is 40% - 80% of the bed material IV amount. The injection amount of the oxygen carrier V is regulated according to the ammonia-blended combustion efficiency of the boiler. Within this usage range, the oxygen carrier V can realize the oxygen absorption - release reaction in the dense phase bed and the dilute phase bed, realize the regulation of the oxygen distribution in the furnace cavity, and at the same time can also avoid the material waste caused by adding too much oxygen carrier V.

[0042] The oxygen carrier V material is a natural ore or an artificial synthetic material containing active components, including non-precious metal components and / or precious metal components. The active metal components of the oxygen carrier V should include one or several of non-precious metal components such as Fe, Ni, Cu, etc. and precious metal components such as Ru, Ir, Pt, Mo, W, Zr, etc.

[0043] Oxygen carrier V should be made of materials with smooth surface and good sphericity, and the particle size can be selected from 100μm to 500μm, and the particle size is 100μm to 500μm, and more preferably, the particle size is selected from 200μm to 350μm. This particle size selection is convenient for oxygen absorption and release due to its large specific surface area. On the other hand, there is still sufficient gap between adjacent oxygen carriers V for ammonia and combustion-supporting wind to pass through, so as to maintain the normal reaction in the container. At the same time, this particle size also makes it easy for oxygen carrier V to roll in the furnace 2. When its particle size is too large, it is not easy to move under the promotion of primary wind I and secondary wind II due to its own gravity. If its particle size is small, it may be entrained by the flue gas generated by combustion in the furnace due to its small volume and light overall mass, and enter the outside of the furnace with the flue gas, resulting in material waste.

[0044] The catalytic decomposition conversion rate of oxygen carrier V for ammonia in the reduced state is 20% to 90%. Ammonia burns normally in the oxygen-rich zone and burns incompletely in the oxygen-deficient zone. However, most of the oxygen carrier V can be reduced to low-valent metal oxides or metal elements in the reducing combustion zone and release oxygen molecules. On the one hand, under the catalytic action of low-valent metal oxides or metal elements, the released oxygen molecules can promote the catalytic oxidation of ammonia in the reducing zone and improve the combustion efficiency of ammonia; on the other hand, ammonia can be decomposed into nitrogen and hydrogen under the catalytic action of the metal of oxygen carrier V in a reducing atmosphere. Hydrogen has better combustion performance than ammonia and is a typical fuel for improving the efficiency of ammonia / coal co-combustion.

[0045] It should be noted that the filling position of the oxygen carrier V can be filled through a limestone feeding system, a fuel coal feeding system or a special feeding system according to the actual conditions on site. This type of feeding system is a prior art and its specific structure is not described here. In this embodiment, a solid feeding system 3 is connected to the side wall of the furnace 2, and fixed materials such as coal powder and solid bed material can be added to the furnace 2 through the solid feeding system.

[0046] An ammonia inlet (not shown in the figure) is also provided on the furnace 2. During use, ammonia enters the furnace 2 through the ammonia inlet, and coal powder III, solid bed material IV and oxygen carrier V are added into the furnace 2. The oxygen carrier V circulates back and forth in the furnace 2 under the action of primary air I, secondary air II and its own gravity, which can promote the combustion of ammonia-coal.

[0047] During system operation, the oxygen carrier Ⅴ reciprocates between the reduction combustion zone of the dense phase bed and the oxidation combustion zone of the dilute phase bed, continuously undergoing the oxygen absorption - oxygen release process. In the dense phase bed, the oxidized oxygen carrier Ⅴ can use its bound oxygen for the oxidation of ammonia and partially convert it into the reduced state. The reduced oxygen carrier Ⅴ can play a certain catalytic decomposition role on ammonia, generating hydrogen that is easier to burn to promote fuel burnout and simultaneously controlling NOx emissions; in the dilute phase bed, the oxidized oxygen carrier Ⅴ can play a catalytic oxidation role on ammonia to further promote ammonia oxidation.

[0048] The ammonia inlet is located between the primary air inlet 7 and the secondary air inlet 8. Vertically, the distance between the ammonia inlet and the primary air inlet 7 is less than the distance between the ammonia inlet and the secondary air inlet 8.

[0049] It can be understood that in this technical solution, the ammonia injection position can be introduced between the primary air I and the secondary air II or from a position closer to the primary air I according to the actual on - site conditions. As a preferred technical solution of the present invention, ammonia is injected from a position closer to the primary air I between the primary and secondary air II.

[0050] Introducing ammonia into the furnace 2 from a position between the primary air I and the secondary air II and close to the primary air inlet 7 can extend the residence time of ammonia in the furnace 2 and enable ammonia to be more fully utilized. Since the pulverized coal Ⅲ and the oxygen carrier Ⅴ are mainly concentrated in the lower middle part of the furnace 2, if the ammonia inlet is set above the secondary air II, the ammonia needs to reach the vicinity of the pulverized coal Ⅲ and the oxygen carrier Ⅴ before it can play its role, resulting in a relatively large demand for ammonia. In the present invention, the ammonia inlet is set between the primary air I and the secondary air II, and the ammonia entering the furnace 2 can cooperate with the pulverized coal Ⅲ and the oxygen carrier Ⅴ to play a role in a short time, improving the utilization efficiency of ammonia.

[0051] Example 3

[0052] The main structure of this example is the same as that of Example 2. The difference is that in this example, the primary air inlet 7 is connected to an ammonia gas source, that is, ammonia enters the air chamber 1 along with the primary air I of the primary air inlet 7. After the ammonia and the primary air I are evenly mixed in the air chamber 1, they are then sent into the furnace 2 together. This way of introducing ammonia into the furnace 2 can further increase the residence time of ammonia in the furnace 2 and make full use of ammonia.

[0053] Example 4

[0054] This embodiment has the same main structure as Embodiment 2 or Embodiment 3. The difference is that this embodiment further includes a cyclone separator 4 and a return material device 5. The flue gas outlet provided at the upper part of the furnace 2 is communicated with the feed inlet of the cyclone separator 4 through a pipeline. A separated gas outlet 6 is provided at the top of the cyclone separator 4 to discharge the separated gas VI separated by the cyclone separator 4. A separated solid outlet communicated with the return material device 5 is provided at the bottom of the cyclone separator 4. The discharge outlet of the return material device 5 is connected to the side wall of the furnace 2, and the return material device 5 and the solid feeding system 3 are respectively arranged on both sides of the furnace.

[0055] During the use process, pulverized coal III, solid bed material IV and oxygen carrier V are added into the circulating fluidized bed boiler through the solid feeding system 3. Compared with the coal combustion system of the traditional circulating fluidized bed boiler, after using the oxygen carrier V to replace part or all of the original bed material IV, the fuel ammonia enters the furnace 2 alone or is introduced into the air chamber 1 together with the primary air I. After being fully mixed, it enters the furnace 2. Subsequently, the oxygen carrier V reciprocally circulates in the furnace 2 under the action of the primary air I, secondary air II and its own gravity, promoting the combustion of ammonia-coal fuel. The flue gas generated after combustion carries some solid materials into the cyclone separator 4. After gas-solid separation by the cyclone separator 4, the separated gas VI is discharged from the cyclone exhaust port, and the solid materials are sent back to the furnace 2 through the return material device 5 for recycling.

[0056] When the system operates, the oxygen carrier V reciprocally circulates between the reduction combustion zone of the dense phase bed and the oxidation combustion zone of the dilute phase bed, continuously undergoing the oxygen absorption-oxygen release process. In the dense phase bed, the oxidized oxygen carrier V can use its combined oxygen for the oxidation of ammonia and partially convert it into the reduced state. The reduced oxygen carrier V can play a certain catalytic decomposition role on ammonia, generating hydrogen that is easier to burn to promote the complete combustion of the fuel and simultaneously controlling NOx emissions. In the dilute phase bed, the oxidized oxygen carrier V can play a catalytic oxidation role on ammonia, further promoting the oxidation of ammonia. Therefore, this embodiment not only maintains the reaction principle in the use process of the above embodiments, but also after the solid materials discharged with the flue gas are separated by the cyclone separator 4, the solid materials continue to be returned to the furnace 2 for recycling. The solid materials include unburned pulverized coal and a small number of oxygen carriers with smaller particles, etc. The recycling of the solid materials can enable the pulverized coal to burn fully, improve the utilization rate of the oxygen carrier, and save the application cost of the system. The gas separated by the cyclone separator is discharged outside the device, which also reduces the pressure on the atmospheric environment or the subsequent treatment system.

[0057] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An oxygen carrier-enhanced circulating fluidized bed boiler ammonia-doped carbon reduction combustion method, characterized in that: Ammonia gas and combustion-supporting air are introduced into the furnace with pulverized coal and oxygen carrier. The oxygen carrier reciprocally circulates in the furnace under the action of the combustion-supporting air and its own gravity. In the dense phase bed layer in the furnace, the oxidized oxygen carrier uses its bound oxygen for the oxidation of ammonia and is partially converted into the reduced state. The reduced oxygen carrier catalytically decomposes ammonia to produce hydrogen, and at the same time controls NOx emissions; in the dilute phase bed layer in the furnace, the oxidized oxygen carrier catalytically oxidizes ammonia to promote the combustion of ammonia-coal fuel.

2. An oxygen carrier enhanced circulating fluidized bed boiler combustion method with ammonia blending for carbon reduction, characterized in that: The combustion-supporting air includes primary air and secondary air, and the primary air inlet (7) is located below the primary air inlet (7).

3. An oxygen carrier-enhanced circulating fluidized bed boiler ammonia-doped carbon reduction combustion system, based on the oxygen carrier-enhanced circulating fluidized bed boiler ammonia-doped carbon reduction combustion method described in claim 2, characterized in that, It includes a furnace (2), a wind chamber (1) is provided at the bottom of the furnace (2), a primary air inlet (7) is opened on the wind chamber (1), a primary air inlet (7) is opened on the side wall of the furnace (2), and a flue gas outlet is provided at the upper part of the furnace (2).

4. An oxygen carrier enhanced circulating fluidized bed boiler ammonia-doped carbon reduction combustion system according to claim 3, characterized in that, An ammonia gas inlet is also opened on the furnace (2), and the ammonia gas inlet is located between the primary air inlet (7) and the primary air inlet (7).

5. The oxycarrier-enhanced circulating fluidized bed boiler ammonia-doped and carbon-reducing combustion system according to claim 3, wherein The primary air inlet (7) is connected to an ammonia gas source.

6. The oxy-carrier enhanced circulating fluidized bed boiler ammonia-doped carbon capture combustion system according to claim 3, characterized in that, The amount of oxygen carrier used in the furnace (2) is 10% - 100% of the bed material amount, and the balance is solid bed material.

7. An oxygen carrier-enhanced circulating fluidized bed boiler ammonia-doped carbon reduction combustion system according to claim 6, characterized in that, The amount of oxygen carrier used is 40% - 80% of the bed material amount.

8. The oxycarrier-enhanced circulating fluidized bed boiler ammonia-doped carbon capture combustion system according to claim 3, wherein The oxygen carrier material is a natural ore or synthetic material containing active components, including non-precious metal components and / or precious metal components.

9. The oxycarrier-enhanced circulating fluidized bed boiler ammonia-doped and carbon-reduced combustion system according to claim 8, wherein The oxygen carrier is a smooth spherical shape with a particle size of 100μm - 500μm. In the reduced state, the catalytic decomposition conversion rate of the oxygen carrier to ammonia is 20% - 90%.

10. A combustion system for oxycarrier-enhanced circulating fluidized bed boiler with ammonia injection for carbon reduction, according to any one of claims 3-9, characterized in that It also includes a cyclone device (4) and a return device (5). A flue gas outlet is provided at the upper part of the furnace (2), and the flue gas outlet is communicated with the feed inlet of the cyclone device (4) through a pipeline; a separated gas outlet is provided at the top of the cyclone device (4), and a separated solid outlet communicated with the return device (5) is provided at the bottom. The discharge outlet of the return device (5) is connected to the side wall of the furnace (2).

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