Flue gas recirculation system for biomass oxygen-enriched combustion CFB boiler
By using the flue gas recirculation system of the biomass oxygen-enriched combustion CFB boiler, the mixture of flue gas and pure oxygen is used as the combustion-supporting gas, which solves the problems of low combustion efficiency and low CO2 concentration in existing oxygen-enriched combustion CFB boilers, and achieves high-efficiency combustion and CO2 purification.
Patent Information
- Application Number
- CN202520156142.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2026-01-27
- Estimated Expiration
- 2035-01-22
AI Technical Summary
Existing oxygen-enriched combustion CFB boilers have low combustion efficiency and low CO2 concentration in flue gas, making them difficult to purify or capture.
Design a flue gas recirculation system for a biomass oxygen-enriched combustion CFB boiler. Through multiple flue gas recirculations, the flue gas is mixed with pure oxygen using a secondary air fan and a primary air fan, and then introduced into the boiler as a combustion-supporting gas to increase the CO2 concentration and enhance combustion efficiency.
It significantly increases the CO2 concentration in flue gas, facilitating subsequent purification or capture, improving combustion efficiency, and can be used to prepare chemical products.
Smart Images
Figure CN223840354U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a flue gas recirculation system for a biomass oxygen-enriched combustion CFB boiler, belonging to the field of CFB boiler technology. Background Technology
[0002] Biomass oxygen-enriched combustion (CFB) technology can be widely applied in the combined use of wind and solar power to produce green methanol. Wind and solar power, among other green energy sources, can produce pure oxygen and hydrogen through water electrolysis.
[0003] Oxygen-enriched combustion in coal-fired boilers occurs in an environment of O2 and CO2. On the one hand, existing oxygen-enriched combustion CFB boilers have low combustion efficiency due to their own structural reasons; on the other hand, the CO2 concentration in the flue gas is low, making it difficult to purify or capture CO2 in subsequent flue gas treatment systems.
[0004] In summary, existing oxygen-enriched combustion CFB boilers suffer from technical problems due to their inherent structure, including low combustion efficiency, low CO2 concentration in flue gas, and difficulty in purification or capture. Utility Model Content
[0005] This invention aims to address the technical problems of existing oxygen-enriched combustion CFB boilers, which suffer from low combustion efficiency and low CO2 concentration in flue gas due to their structural limitations, making purification or capture difficult. The invention provides a flue gas recirculation system for biomass oxygen-enriched combustion CFB boilers.
[0006] The technical solution of this utility model is a flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler. It includes an oxy-fuel combustion CFB boiler, an air preheater, a dust removal device, a desulfurization device, a flue gas cooler, a secondary air fan, a primary air fan, and a high-pressure fluidizing fan. The oxy-fuel combustion CFB boiler is provided with a flue gas outlet. The flue gas outlet of the oxy-fuel combustion CFB boiler is connected to the dust removal device through the air preheater. The dust removal device is connected to the desulfurization device. The desulfurization device is connected to the flue gas cooler. The flue gas cooler is connected to the secondary air fan. The secondary air fan is connected to both the primary air fan and the oxy-fuel combustion CFB boiler. The secondary air fan is connected to the oxy-fuel combustion CFB boiler through the air preheater.
[0007] The primary air fan is connected to both the oxygen-enriched combustion CFB boiler and the high-flow fan. The primary air fan is connected to the oxygen-enriched combustion CFB boiler through an air preheater, and the high-flow fan is also connected to the oxygen-enriched combustion CFB boiler.
[0008] As another improvement of this utility model, the oxygen-enriched combustion CFB boiler is also equipped with a secondary air box, and the secondary air fan is connected to the secondary air box of the oxygen-enriched combustion CFB boiler through an air preheater.
[0009] As another improvement of this utility model, the secondary fan is connected to the air preheater through a flue, and the flue gas composition in the flue between the secondary fan and the air preheater includes oxygen injected from outside the flue.
[0010] As another improvement of this utility model, the oxygen content in the flue gas in the flue between the secondary fan and the air preheater ranges from 23% to 27%.
[0011] As another improvement of this utility model, the oxygen-enriched combustion CFB boiler is also equipped with a water-cooled air chamber, and the primary air fan is connected to the water-cooled air chamber of the oxygen-enriched combustion CFB boiler through an air preheater.
[0012] As another improvement of this utility model, the primary air fan is connected to the air preheater through a flue, and the flue gas composition in the flue between the primary air fan and the air preheater includes oxygen injected from outside the flue.
[0013] As another improvement of this utility model, the oxygen content in the flue gas in the flue between the primary air blower and the air preheater ranges from 23% to 27%.
[0014] As another improvement of this utility model, the oxygen-enriched combustion CFB boiler is also equipped with a return valve, and the high-flow fan is connected to the return valve of the oxygen-enriched combustion CFB boiler.
[0015] The beneficial effects of this utility model are:
[0016] 1. This utility model discloses a flue gas recirculation system for a biomass oxygen-enriched combustion CFB boiler. Part of the flue gas after desulfurization first passes through a flue gas cooler. After passing through the flue gas cooler, some liquid water droplets contained in the flue gas are removed, which avoids the liquid water droplets mixed in the fan and affecting its operational safety. After the flue gas is mixed with pure oxygen, it enters an air preheater for preheating, and then enters the oxygen-enriched combustion CFB boiler to improve combustion efficiency.
[0017] 2. After multiple flue gas cycles, the CO2 concentration in the flue gas will be significantly increased, which will facilitate the purification or capture of CO2 in subsequent flue gas treatment equipment. The purified CO2 can be used as a raw material to prepare chemical products such as methanol. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of a flue gas recirculation system for a biomass oxygen-enriched combustion CFB boiler according to the present invention. The arrows in the diagram represent the direction of flue gas flow. Detailed Implementation
[0019] The technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. All embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.
[0020] Specific implementation method one: Combining Figure 1 This embodiment describes a flue gas recirculation system for a biomass oxy-fuel CFB boiler. It includes an oxy-fuel CFB boiler 1, an air preheater 2, a dust removal device 3, a desulfurization device 4, a flue gas cooler 5, a secondary air fan 7, a primary air fan 8, and a high-pressure fluidizing fan 9. The oxy-fuel CFB boiler 1 has a flue gas outlet. The flue gas outlet of the oxy-fuel CFB boiler 1 is connected to the dust removal device 3 via the air preheater 2. The dust removal device 3 is connected to the desulfurization device 4. The desulfurization device 4 is connected to the flue gas cooler 5. The flue gas cooler 5 is connected to the secondary air fan 7. The secondary air fan 7 is connected to both the primary air fan 8 and the oxy-fuel CFB boiler 1. The secondary air fan 7 is connected to the oxy-fuel CFB boiler 1 via the air preheater 2.
[0021] The primary air fan 8 is connected to the oxygen-enriched combustion CFB boiler 1 and the high-pressure fluidizing fan 9 respectively. The primary air fan 8 is connected to the oxygen-enriched combustion CFB boiler 1 through the air preheater 2, and the high-pressure fluidizing fan 9 is connected to the oxygen-enriched combustion CFB boiler 1.
[0022] The recirculated flue gas process involves a portion of the flue gas that has passed through the desulfurization equipment first passing through a flue gas cooler. After passing through the flue gas cooler, some of the liquid water droplets contained in the flue gas are removed, thus preventing liquid water droplets from mixing into the fan and affecting its operational safety.
[0023] The flue gas then enters the secondary fan for pressurization, and a portion of the flue gas enters the flue gas treatment equipment 6;
[0024] A portion of the flue gas from the secondary air fan outlet is mixed with pure oxygen and then enters the air preheater for preheating. It then enters the boiler as secondary air for staged combustion and participates in combustion inside the boiler.
[0025] Another portion of the flue gas from the secondary air fan outlet enters the primary air fan for repressurization.
[0026] A portion of the flue gas from the primary air blower outlet is mixed with pure oxygen and then enters the air preheater for preheating. It then enters the boiler as primary fluidizing air to ensure that the material is fully fluidized and participates in combustion.
[0027] Another portion of the flue gas from the primary blower outlet enters the high-pressure fluidizing blower for further pressurization, then enters the air preheater for preheating, and finally enters the boiler as high-pressure fluidizing air. This ensures the full fluidization of the materials inside the boiler, and the various equipment are connected by flue ducts.
[0028] After multiple flue gas cycles, the CO2 concentration in the flue gas will increase significantly, which will facilitate the purification or capture of CO2 in subsequent flue gas treatment equipment. The purified CO2 can be used as a raw material to prepare chemical products such as methanol.
[0029] Specific Implementation Method Two: Combining Figure 1 This embodiment differs from Specific Embodiment 1 in that the oxygen-enriched combustion CFB boiler 1 is further equipped with a secondary air box. The secondary air fan 7 is connected to the secondary air box of the oxygen-enriched combustion CFB boiler 1 via an air preheater 2. A portion of the flue gas from the secondary air fan outlet is mixed with pure oxygen and then enters the air preheater for preheating. It then enters the boiler's secondary air box as secondary air for staged combustion and participates in combustion inside the boiler. Other components and connections are the same as in Specific Embodiment 1.
[0030] Specific implementation method three: Combining Figure 1 This embodiment differs from specific embodiment one in that the secondary air fan 7 is connected to the air preheater 2 via a flue. The flue gas in the flue between the secondary air fan 7 and the air preheater 2 includes oxygen injected from outside the flue. By controlling the proportion of pure oxygen mixed in the recirculated flue gas, the oxygen concentration is controlled at approximately 25%. This mixture of recirculated flue gas and oxygen replaces air as the combustion gas in the boiler, achieving oxygen-enriched combustion and thus improving combustion efficiency. Other components and connections are the same as in specific embodiment one or two.
[0031] Specific implementation method four: Combination Figure 1 This embodiment differs from specific embodiment one in that the oxygen content in the flue gas within the flue between the secondary air fan 7 and the air preheater 2 ranges from 23% to 27%. By controlling the proportion of pure oxygen mixed into the recirculated flue gas, the oxygen concentration is controlled at 23% to 27%. This mixture of recirculated flue gas and oxygen replaces air as the combustion-supporting gas in the boiler, achieving oxygen-enriched combustion and thus improving combustion efficiency. Other components and connections are the same as in any one of specific embodiments one through three.
[0032] Specific Implementation Method Five: Combining Figure 1This embodiment differs from specific embodiment one in that the oxygen-enriched combustion CFB boiler 1 also includes a water-cooled air chamber. The primary air fan 8 is connected to the water-cooled air chamber of the oxygen-enriched combustion CFB boiler 1 via an air preheater 2. A portion of the flue gas from the primary air fan outlet is mixed with pure oxygen and then enters the air preheater for preheating. It then enters the boiler's water-cooled air chamber as primary fluidizing air, ensuring sufficient fluidization of the material and its participation in combustion. Other components and connections are the same as in any one of specific embodiments one through four.
[0033] Specific Implementation Method Six: Combination Figure 1 This embodiment differs from specific embodiment one in that the primary air fan 8 is connected to the air preheater 2 via a flue. The flue gas in the flue between the primary air fan 8 and the air preheater 2 includes oxygen injected from outside the flue. By controlling the proportion of pure oxygen mixed in the recirculated flue gas, the oxygen concentration is controlled at approximately 25%. This mixture of recirculated flue gas and oxygen replaces air as the combustion gas in the boiler, achieving oxygen-enriched combustion and thus improving combustion efficiency. Other components and connections are the same as in any one of specific embodiments one through five.
[0034] Specific implementation method seven: Combination Figure 1 This embodiment differs from specific embodiment one in that the oxygen content in the flue gas within the flue between the primary air fan 8 and the air preheater 2 ranges from 23% to 27%. By controlling the proportion of pure oxygen mixed into the recirculated flue gas, the oxygen concentration is controlled at 23% to 27%. This mixture of recirculated flue gas and oxygen replaces air as the combustion-supporting gas in the boiler, achieving oxygen-enriched combustion and thus improving combustion efficiency. Other components and connections are the same as in any one of specific embodiments one through six.
[0035] Specific implementation method eight: Combination Figure 1 This embodiment differs from specific embodiment one in that the oxygen-enriched combustion CFB boiler 1 is also equipped with a return valve, and the high-pressure fluidizing blower 9 is connected to the return valve of the oxygen-enriched combustion CFB boiler 1. Another portion of the flue gas from the primary air blower outlet enters the high-pressure fluidizing blower for further pressurization, then enters the air preheater for preheating, and finally enters the return valve as high-pressure fluidizing air, ensuring sufficient fluidization of the material inside the return valve. Other components and connections are the same as in any one of specific embodiments one through seven.
[0036] Combination Figure 1 Explanation of the working principle of this utility model:
[0037] The recirculated flue gas process involves a portion of the flue gas passing through the desulfurization equipment. First, it passes through a flue gas cooler, which removes some liquid water droplets, preventing them from entering the blower. The flue gas then enters a secondary air blower for pressurization, with a portion entering the flue gas treatment equipment. A portion of the flue gas from the secondary air blower outlet is mixed with pure oxygen and preheated in an air preheater before entering the boiler as secondary air for staged combustion. Another portion of the flue gas from the secondary air blower outlet enters a primary air blower for further pressurization. A portion of the flue gas from the primary air blower outlet is mixed with pure oxygen and preheated in an air preheater before entering the boiler as primary fluidizing air to ensure sufficient fluidization of the materials and their participation in combustion. The remaining portion of the flue gas from the primary air blower outlet enters a high-pressure fluidizing blower for further pressurization, then enters an air preheater for preheating, and finally enters the boiler as high-pressure fluidizing air, ensuring sufficient fluidization of the materials inside the boiler. All equipment is connected by flue ducts.
[0038] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.
Claims
1. A flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler, characterized in that... It includes an oxygen-enriched combustion CFB boiler (1), an air preheater (2), a dust removal device (3), a desulfurization device (4), a flue gas cooler (5), a secondary air fan (7), a primary air fan (8), and a high-pressure fluidizing fan (9). The oxygen-enriched combustion CFB boiler (1) is equipped with a flue gas outlet. The flue gas outlet of the oxygen-enriched combustion CFB boiler (1) is connected to the dust removal device (3) through the air preheater (2). The dust removal device (3) is connected to the desulfurization device (4). The desulfurization device (4) is connected to the flue gas cooler (5). The flue gas cooler (5) is connected to the secondary air fan (7). The secondary air fan (7) is connected to the primary air fan (8) and the oxygen-enriched combustion CFB boiler (1) respectively. The secondary air fan (7) is connected to the oxygen-enriched combustion CFB boiler (1) through the air preheater (2). The primary air fan (8) is connected to the oxygen-enriched combustion CFB boiler (1) and the high-pressure fluidizing fan (9) respectively. The primary air fan (8) is connected to the oxygen-enriched combustion CFB boiler (1) through the air preheater (2), and the high-pressure fluidizing fan (9) is connected to the oxygen-enriched combustion CFB boiler (1).
2. The flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler according to claim 1, characterized in that, The oxygen-enriched combustion CFB boiler (1) is also equipped with a secondary air box, and the secondary air fan (7) is connected to the secondary air box of the oxygen-enriched combustion CFB boiler (1) through the air preheater (2).
3. A flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler according to claim 2, characterized in that, The secondary air fan (7) is connected to the air preheater (2) through a flue. The flue gas in the flue between the secondary air fan (7) and the air preheater (2) includes oxygen injected from outside the flue.
4. A flue gas recirculation system for a biomass oxygen-enriched combustion CFB boiler according to claim 3, characterized in that, The oxygen content in the flue gas between the secondary fan (7) and the air preheater (2) ranges from 23% to 27%.
5. A flue gas recirculation system for a biomass oxygen-enriched combustion CFB boiler according to claim 1, characterized in that, The oxygen-enriched combustion CFB boiler (1) is also equipped with a water-cooled air chamber, and the primary air fan (8) is connected to the water-cooled air chamber of the oxygen-enriched combustion CFB boiler (1) through the air preheater (2).
6. A flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler according to claim 5, characterized in that, The primary air fan (8) is connected to the air preheater (2) through a flue. The flue gas in the flue between the primary air fan (8) and the air preheater (2) includes oxygen injected from outside the flue.
7. A flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler according to claim 6, characterized in that, The oxygen content in the flue gas between the primary air fan (8) and the air preheater (2) ranges from 23% to 27%.
8. A flue gas recirculation system for a biomass oxy-fuel combustion CFB boiler according to claim 1, characterized in that, The oxygen-enriched combustion CFB boiler (1) is also equipped with a return valve, and the high-pressure fluidizing blower (9) is connected to the return valve of the oxygen-enriched combustion CFB boiler (1).