Pulverized coal-biomass efficient co-combustion low-carbon boiler equipment

Abstract

The invention discloses pulverized coal-biomass efficient co-combustion low-carbon boiler equipment, and belongs to the technical field of boiler combustion equipment. A conventional pulverized coal combustion system is arranged on the upper middle portion of the hearth, and a biomass feeding and combustion system is arranged on the lower portion of the hearth. A heat exchange assembly is arranged at the top of the hearth; water cooling walls are arranged on the periphery of the hearth, and the heat exchange assembly and the water cooling walls absorb heat and convert the heat into ultra-supercritical parameter steam. The biomass feeding and combustion system is used for conveying and combusting biomass, the conventional pulverized coal combustion system is used for combusting pulverized coal, and heat generated by combustion of the biomass and the pulverized coal exchanges heat with the water cooling wall through the heat exchange assembly. The pulverized coal-biomass efficient co-combustion low-carbon boiler equipment can effectively solve the double challenges of environmental pollution and energy sustainability caused by pulverized coal boiler power generation in the prior art, and the problems of poor economical efficiency of biomass combustion power generation and the like.

Description

Technical Field

[0001] This invention belongs to the field of boiler combustion equipment technology. Specifically, it relates to a low-carbon boiler equipment for efficient co-combustion of pulverized coal and biomass. Background Technology

[0002] While traditional pulverized coal boiler power generation technology is mature, it faces the dual challenges of environmental pollution and energy sustainability. Biomass energy, as a renewable and environmentally friendly energy form, is of great significance for reducing greenhouse gas emissions and alleviating energy shortages. To promote clean energy utilization, many large power plants have begun using pulverized coal boilers with biomass co-firing technology. Currently, the mainstream technical route for pulverized coal boilers with biomass co-firing is biomass pelleting and pulverization followed by combustion. However, due to the low density and calorific value of biomass, the cost of conventional co-firing is too high after processes such as collection, transportation, pelleting, pulverization, and combustion. On the other hand, an excessively high biomass co-firing ratio may lead to unstable combustion and decreased boiler efficiency. Therefore, conventional pulverized coal boilers generally control the co-firing ratio to ensure stable combustion and keep boiler efficiency within a relatively economical range. Current co-firing methods are uneconomical due to the high energy consumption of biomass pelleting and pulverization, requiring substantial subsidies to avoid losses.

[0003] In China, water-cooled vibrating grate technology has been widely applied in fields such as biomass power generation. This technology, through the combination of vibration mechanism and cooling system, achieves uniform distribution and efficient combustion of solid fuel, reducing the emission of harmful substances. Compared with conventional pulverized coal boilers co-firing biomass, it has advantages such as superior anti-coking performance and lower fuel pretreatment requirements. While simple grate boilers burning biomass have low combustion costs, their disadvantages include low main unit parameters (generally high-temperature and high-pressure parameters), resulting in poor economic efficiency for power plants.

[0004] This proposed pulverized coal-biomass high-efficiency co-fired low-carbon boiler system organically integrates biomass grate boilers and conventional pulverized coal boilers. It perfectly combines the thermal efficiency and economic benefits of pulverized coal boilers with the low cost and environmental friendliness of biomass combustion in biomass grate boilers. This provides a completely new and perfect solution for clean and carbon-reducing power generation through coal-fired and biomass co-firing. While optimizing the energy structure and reducing carbon emissions, it also ensures the power supply of coal-fired power plants. This system will have profound significance in the green and low-carbon development of coal-fired power units. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency, low-carbon coal-biomass co-combustion boiler system to address the aforementioned shortcomings, thereby solving the dual challenges of environmental pollution and energy sustainability caused by existing coal-fired boiler power generation, as well as the poor economic viability of biomass combustion power generation. To achieve the above objective, this invention provides the following technical solution: A high-efficiency co-combustion low-carbon coal-biomass boiler includes a furnace; a conventional coal combustion system is provided in the upper middle part of the furnace, and a biomass feeding and combustion system is provided in the lower part of the furnace; a heat exchange component is provided at the top of the furnace; and water-cooled walls are provided around the furnace. The heat exchange component and the water-cooled walls absorb heat and convert it into ultra-supercritical steam. The biomass feeding and combustion system is used to transport and burn biomass, and the conventional coal combustion system is used to burn coal. The heat generated by the combustion of biomass and coal is exchanged with the water-cooled walls through the heat exchange component.

[0006] Furthermore, the conventional pulverized coal combustion system includes several sets of conventional pulverized coal burners evenly arranged along the front and rear walls or four corners of the furnace; the side walls of the furnace are provided with pulverized coal feeding pipes.

[0007] Furthermore, the biomass feeding and combustion system includes a biomass feeding assembly and a water-cooled vibrating grate; the grate of the water-cooled vibrating grate is inclinedly arranged in the lower part of the furnace to support the combustion of biomass; the biomass feeding assembly is used to control the delivery of biomass to the grate.

[0008] Furthermore, the biomass feeding assembly includes a biomass silo and a feeder; the biomass silo is connected to the feeder via a conveying pipe; the feeder is connected to the furnace via a conveying pipe, forming a biomass inlet on the furnace; the biomass inlet is located on the upwardly inclined side of the grate.

[0009] Furthermore, the bottom of the grate is provided with several grate air chambers; the bottom of each of the several grate air chambers is provided with a primary air inlet for blowing in primary air to provide oxygen for biomass combustion.

[0010] Furthermore, the lower side wall of the furnace is provided with a secondary air inlet for blowing secondary air onto the grate.

[0011] Furthermore, the biomass feeding and combustion system includes an ignition oil propeller disposed on the lower side wall of the furnace, used to send the ignition oil gun into the furnace to ignite the biomass.

[0012] Furthermore, the bottom of the furnace is provided with a slag discharge port; the slag discharge port is located below the downward-sloping side of the grate.

[0013] Furthermore, the heat exchange assembly includes a screen-type superheater, a rear screen superheater, a high-temperature superheater, and a high-temperature reheater, which are sequentially arranged on the horizontal flue at the top of the furnace to absorb heat from the flue gas.

[0014] Furthermore, the heat exchange assembly includes several sets of low-temperature reheaters and low-temperature economizers, which are arranged sequentially on the tail flue at the rear end of the horizontal flue to absorb heat from the flue gas.

[0015] The beneficial effects of this invention are: This invention combines a conventional pulverized coal combustion system with a biomass feeding and combustion system, utilizing biomass to reduce coal consumption, optimize the energy structure, and lower carbon emissions while ensuring the power supply of coal-fired power plants. It is an effective method to achieve the "dual carbon" goal and has profound significance in the green and low-carbon development of coal-fired units. At the same time, it can increase the proportion of biomass co-firing, achieving efficient coupling between biomass and coal. It eliminates the biomass granulation and grinding process, and utilizes the advantage of water-cooled vibrating grate with low requirements for biomass pretreatment, thereby reducing co-firing costs. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the present invention; In the attached diagram: 1. Furnace; 2. Conventional pulverized coal combustion system; 3. Biomass feeding and combustion system; 4. Conventional pulverized coal burner; 5. Grate; 6. Biomass silo; 7. Feeder; 8. Grate air chamber; 9. Primary air; 10. Secondary air; 11. Ignition oil propeller; 12. Ash discharge port; 13. Screen-type superheater; 14. Rear screen superheater; 15. High-temperature superheater; 16. High-temperature reheater; 17. Low-temperature reheater; 18. Low-temperature economizer. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0020] In the description of this invention, "a plurality of" means two or more.

[0021] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0022] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0023] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," and "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0024] Example 1 See attached Figure 1 This embodiment discloses a low-carbon boiler equipment for high-efficiency co-combustion of pulverized coal and biomass, including a furnace 1. Through the functional zoning design of the furnace 1, the conventional pulverized coal combustion system 2 and the biomass feeding and combustion system 3 are organically coupled. This equipment is suitable for newly built units of 300MW, 600MW, and 1000MW. Specifically, the furnace 1 is a vertically arranged closed cavity structure. The furnace 1 is divided into a lower biomass combustion zone and a middle and upper pulverized coal combustion zone along its height. The top extends to form a horizontal flue, and the rear end of the horizontal flue connects to the tail flue, forming a complete flue gas flow channel. The middle and upper part of the furnace 1 is equipped with a conventional pulverized coal combustion system 2 for efficient combustion of pulverized coal; the lower part of the furnace 1 is equipped with a biomass feeding and combustion system 3 to achieve stable biomass conveying and stoker combustion; heat exchange components are arranged sequentially at the top of the furnace 1 and in the flue, and water-cooled walls are set around the furnace 1, all for converting the heat energy generated by combustion into ultra-supercritical steam.

[0025] In this embodiment, the conventional pulverized coal combustion system 2 includes several sets of conventional pulverized coal burners 4 and pulverized coal feeding pipes. The number of conventional pulverized coal burners 4 is adapted according to the furnace capacity 1 and the unit level to ensure that the flame generated by pulverized coal combustion can evenly cover the upper and middle areas of the furnace 1, avoiding localized high temperatures or combustion dead zones. All conventional pulverized coal burners 4 are evenly fixed to the front and rear walls or four corners of the upper and middle parts of the furnace 1, and are equipped with a sealing structure to prevent flue gas leakage. The connection positions of the pulverized coal feeding pipes to the side walls of the furnace 1 correspond one-to-one with the conventional pulverized coal burners 4. One end of the pulverized coal feeding pipe is connected to the outlet of the coal mill, and the other end is sealed and connected to the feed inlet of the conventional pulverized coal burner 4, continuously and stably conveying pulverized coal through the coal mill.

[0026] The biomass feeding and combustion system 3 includes a water-cooled vibrating grate, with the grate 5 inclined and positioned at the bottom of the furnace 1. The water-cooled vibrating grate is a well-known structure to those skilled in the art and will not be described in detail here. The vibration frequency and amplitude of the grate 5 can be controlled by an external control cabinet, periodically generating slight vibrations to prevent biomass from adhering to the grate 5 and improve combustion efficiency. Water cooling prevents the grate 5 from deforming or coking due to high temperatures.

[0027] In this embodiment, the biomass feeding and combustion system 3 includes a biomass feeding assembly, which comprises a biomass silo 6 and a feeder 7, connected by a conveying pipe. The biomass silo 6 is located outside the furnace 1, with a feeding port at the top and a discharge port at the bottom. The discharge port of the biomass silo 6 is connected to one end of the conveying pipe, and the other end of the conveying pipe is sealed and connected to the feed port of the feeder 7. The feeder 7 can be a screw feeder 7, which is driven by a motor to rotate its screw blades to achieve quantitative conveying of biomass. The discharge port of the feeder 7 is also sealed and connected to a pre-set biomass feed port on the side wall of the furnace 1 through a conveying pipe. This biomass feed port is located above the upwardly inclined side of the grate 5, ensuring that the biomass fed from the feed port can slide naturally along the inclined direction of the grate 5 and spread evenly on the surface of the grate 5, avoiding local accumulation.

[0028] In this embodiment, several furnace air chambers 8 are provided at the bottom of the grate 5, and the several furnace air chambers 8 evenly cover the entire lower surface of the grate 5. The furnace air chambers 8 are welded by steel structures, and the top is hermetically connected to the bottom of the grate 5 to form an independent air cavity. A primary air inlet is provided at the bottom of each furnace air chamber 8, and a primary air 9 pipe is connected to the primary air inlet. The primary air 9 pipe is communicated with the outlet of the primary air 9 fan supporting the boiler. The primary air 9 is used to ensure sufficient oxygen supply during the biomass layer combustion process. Secondary air inlets are provided on the side wall of the lower part of the furnace 1. The positions of the secondary air inlets are above the grate 5 and are evenly arranged along the circumferential direction of the furnace 1. The secondary air inlets are connected to the secondary air 10 fan supporting the boiler through pipes to blow secondary air 10 into the furnace 1. The secondary air 10 can penetrate the biomass combustion flue gas in the lower part of the furnace 1, fully mix with the unburned particles and volatile gases in the flue gas, supplement the oxygen required for combustion, and reduce the incomplete combustion loss. At the same time, the disturbance effect of the secondary air 10 can promote the mixing of the biomass flue gas and the upper pulverized coal combustion flame, improve the overall combustion efficiency, and reduce the generation of pollutants.

[0029] In this embodiment, the biomass feeding and combustion system 3 further includes an ignition oil pusher 11, which is installed on the side wall of the lower part of the furnace 1 and is close to the biomass feeding port. The ignition oil pusher 11 is composed of a telescopic mechanism and an ignition oil gun. The telescopic mechanism is an electric push rod structure and is connected to the ignition oil gun to realize the feeding and withdrawal of the ignition oil gun.

[0030] In this embodiment, a slag drop port 12 is provided at the bottom of the furnace 1. The slag drop port 12 is located below the inclined side of the grate 5 and has a funnel-shaped structure to facilitate the sliding of ash and slag.

[0031] In this embodiment, the heat exchange component includes a platen superheater 13, a rear platen superheater 14, a high-temperature superheater 15, a high-temperature reheater 16 arranged in the horizontal flue, and a low-temperature reheater 17 and a low-temperature economizer 18 arranged in the tail flue at the rear end of the horizontal flue. The platen superheater 13, the rear platen superheater 14, the high-temperature superheater 15, and the high-temperature reheater 16 are arranged in sequence along the flue gas flow direction of the horizontal flue. The low-temperature reheater 17 and the low-temperature economizer 18 are arranged in sequence along the flue gas flow direction of the tail flue. The feed water forms supercritical or ultra-supercritical parameter steam after the above heat exchange and enters the steam turbine for power generation.

[0032] The pulverized coal-biomass high-efficiency co-firing low-carbon boiler equipment of this embodiment can be used in the pure pulverized coal combustion mode and the pulverized coal-biomass co-firing mode. In the co-firing mode, the biomass blending ratio can be adjusted by the feeder 7 according to the seasonal biomass supply situation, and it has extremely high operation flexibility and reliability.

[0033] This equipment achieves efficient coupling of two fuels through biomass stoker combustion in the lower part of furnace 1 and pulverized coal suspension combustion in the middle and upper parts, combined with staged oxygen supply from primary air 9 and secondary air 10. Biomass is uniformly stoker-fired on a water-cooled vibrating grate, and the uniform supply of primary air 9 ensures complete combustion. The disturbance effect of secondary air 10 promotes the mixing of biomass flue gas and pulverized coal flames, avoiding the defects of single-fuel combustion. Simultaneously, the supercritical parameter design of the conventional pulverized coal combustion system 2 is combined with the environmental advantages of biomass combustion, improving combustion stability and boiler efficiency while reducing greenhouse gas emissions. As a renewable energy source, biomass combustion adds almost no greenhouse gas emissions, can replace part of coal consumption, significantly reduces carbon dioxide emissions from coal combustion, and effectively alleviates energy shortages. Further desulfurization, denitrification, and dust removal equipment can be added at the end of the flue gas passage to achieve ultra-clean emissions of pollutants, resulting in significant social benefits.

[0034] The independent design of the biomass feeding and combustion system 3 and the conventional pulverized coal combustion system 2 enables the equipment to operate in both co-combustion and pure pulverized coal combustion modes, which can be flexibly switched according to the biomass supply. The anti-coking effect of the water-cooled vibrating grate reduces the requirements for biomass pretreatment, eliminates the need for granulation and grinding, simplifies the fuel handling process, and reduces the energy consumption and cost of fuel pretreatment.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A low-carbon boiler equipment for high-efficiency co-combustion of pulverized coal and biomass, characterized in that: The furnace includes a furnace chamber (1); a conventional pulverized coal combustion system (2) is provided in the upper middle part of the furnace chamber (1), and a biomass feeding and combustion system (3) is provided in the lower part of the furnace chamber (1); a heat exchange component is provided at the top of the furnace chamber (1); a water-cooled wall is provided around the furnace chamber (1), and the heat exchange component and the water-cooled wall absorb heat and convert it into ultra-supercritical steam; the biomass feeding and combustion system (3) is used to transport biomass and burn biomass, and the conventional pulverized coal combustion system (2) is used to burn pulverized coal. The heat generated by the combustion of biomass and pulverized coal is exchanged with the water-cooled wall through the heat exchange component.

2. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 1, characterized in that: The conventional pulverized coal combustion system (2) includes several sets of conventional pulverized coal burners (4) evenly arranged along the front and rear walls or four corners of the furnace (1); the side wall of the furnace (1) is provided with a pulverized coal feeding pipe.

3. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 1, characterized in that: The biomass feeding and combustion system (3) includes a biomass feeding assembly and a water-cooled vibrating grate; the grate (5) of the water-cooled vibrating grate is inclinedly arranged in the lower part of the furnace (1) to support the combustion of biomass; the biomass feeding assembly is used to control the delivery of biomass to the grate (5).

4. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 3, characterized in that: The biomass feeding assembly includes a biomass silo (6) and a feeder (7); the biomass silo (6) is connected to the feeder (7) through a conveying pipe; the feeder (7) is connected to the furnace (1) through a conveying pipe, and a biomass inlet is formed on the furnace (1); the biomass inlet is located on the upwardly inclined side of the grate (5).

5. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 3, characterized in that: The grate (5) has several grate air chambers (8) at its bottom; each of the grate air chambers (8) has a primary air inlet at its bottom for blowing in primary air (9) to provide oxygen for biomass combustion.

6. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 3, characterized in that: The lower side wall of the furnace (1) is provided with a secondary air inlet for blowing secondary air (10) into the grate (5).

7. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 1, characterized in that: The biomass feeding and combustion system (3) includes an ignition oil propeller (11) installed on the lower side wall of the furnace (1) for sending the ignition oil gun into the furnace (1) to ignite the biomass.

8. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 3, characterized in that: The furnace chamber (1) is provided with a slag discharge port (12) at the bottom; the slag discharge port (12) is located below the downward-sloping side of the grate (5).

9. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 1, characterized in that: The heat exchange components include a screen-type superheater (13), a rear screen superheater (14), a high-temperature superheater (15), and a high-temperature reheater (16), which are sequentially arranged on the horizontal flue at the top of the furnace (1) to absorb heat from the flue gas.

10. The pulverized coal-biomass high-efficiency co-combustion low-carbon boiler equipment according to claim 9, characterized in that: The heat exchange components include several sets of low-temperature reheaters (17) and low-temperature economizers (18), which are arranged sequentially on the tail flue at the rear end of the horizontal flue to absorb heat from the flue gas.

Images