Combustor arrangement method suitable for biomass blending combustion working condition of coal-fired boiler

Abstract

The invention relates to a combustor arrangement method, in particular to a combustor arrangement method suitable for the biomass blending combustion working condition of a coal-fired boiler. The problems that when an existing coal-fired power plant boiler conducts biomass blending combustion, the blending combustion effect of large-particle biomass is poor, and large-proportion biomass blending combustion is difficult are solved. The vertical hearth and the horizontal hearth are ingeniously combined, and the direct-flow combustors are arranged on the horizontal hearth, so that the combustion stroke of biomass in the hearth is greatly prolonged, sufficient burnout is ensured, a longer moving track is provided for the biomass, and the retention time of the biomass in the hearth is prolonged. In the combustion process, biomass is preliminarily combusted in the horizontal hearth in advance, and pulverized coal is conveyed to the vertical hearth through the pulverized coal combustor to be preliminarily combusted. When the biomass is subjected to blending combustion in a large proportion, the pulverized coal and the biomass are respectively provided with an independent air distribution system; and the combustion process of the pulverized coal and the biomass energy can be independently organized according to the combustion requirements of the pulverized coal and the biomass energy. The invention belongs to the technical field of boilers.

Description

Technical Field

[0001] The invention relates to a burner arrangement method, in particular to a burner arrangement method suitable for a coal-fired boiler operating condition of co-firing biomass, and belongs to the technical field of boilers. Background Art

[0002] Against the backdrop of global efforts to reduce carbon emissions and address climate change, the power industry, a key sector of carbon emissions, is attracting significant attention for its emissions reduction efforts. Optimizing the combustion methods of coal-fired power plant boilers, key components of power generation, to reduce carbon emissions has become a research focus, with biomass co-firing being viewed as a promising approach to emissions reduction.

[0003] Biomass comes from a wide range of sources, including agricultural crop straw and forestry waste. Processing it into pellets for co-firing in power plant boilers can effectively reduce dependence on traditional fossil fuels and significantly reduce greenhouse gas emissions such as carbon dioxide. In actual operation, biomass pellets are ground and then mixed with pulverized coal in the furnace for combustion. When the biomass particle size is small, its large specific surface area allows for sufficient contact with oxygen, facilitating complete combustion and significantly improving the burnout rate. However, as the particle size changes, grinding increases electricity consumption. Electricity costs account for a significant proportion of power generation, and excessive energy consumption can significantly increase the cost of biomass pellet processing, undermining the economic feasibility of co-firing solutions and hindering the large-scale deployment of the technology. If the biomass pellet size is too large, the biomass's residence time in the furnace of traditional coal-fired boilers is limited, resulting in insufficient contact between the particles and oxygen and poor burnout performance. Unburned particles enter the tail flue with the flue gas and easily accumulate in the dust removal equipment, reducing dust removal efficiency and even clogging the equipment, shortening its service life. They also adhere to the surface of the internal components of the desulfurization equipment, interfering with the desulfurization reaction, reducing the desulfurization effect, and in severe cases damaging the equipment, increasing maintenance costs and the number of repairs, and causing many problems for the stable operation of coal-fired power plant boilers. Therefore, the development of a pulverized coal combustion furnace that can ensure the full combustion of large-particle biomass even when co-firing is of great practical significance for balancing the emission reduction benefits and economic costs of biomass co-firing, promoting the widespread application of biomass co-firing technology in power plant boilers, and helping the power industry achieve sustainable low-carbon development.

[0004] In traditional opposed-coal-fired power plant boilers, swirl burners are simply placed on the front and rear walls of the vertical furnace. When it comes to direct biomass co-firing, two common approaches are: First, the two fuels are mixed directly within the swirl burners; second, independent biomass swirl burners are built alongside the pulverized coal swirl burners on the front and rear walls. However, both mixing methods have numerous drawbacks:

[0005] 1. Poor co-firing of large biomass particles: When co-firing large biomass particles, these particles require a longer residence time to achieve complete combustion. However, due to the structural limitations of traditional furnaces, the required residence time of the biomass is insufficient, resulting in poor combustion. Biomass fuel is rich in cellulose, and unburned portions tend to deposit on auxiliary equipment at the rear of the boiler, seriously affecting their proper operation.

[0006] 2. Difficulties in burning large biomass blends: When the biomass blend ratio is significantly increased, due to its high volatile content, the intense combustion of the biomass in the initial combustion phase consumes a significant amount of the air supplied to the furnace. This significantly shortens the time the pulverized coal spends in the oxygen-rich environment, creating a "wind rush" phenomenon that significantly hinders its full combustion. Furthermore, biomass contains a high alkali metal content. When burning large biomass blends, the swirl burner's reliance on the recirculation zone to maintain stable combustion, coupled with the flammable nature of biomass, can easily cause slagging at the swirl burner nozzle, impacting the burner's stable operation and service life.

[0007] Therefore, in order to solve the above technical difficulties, it has become an urgent problem for those skilled in the art to provide a more reasonable burner arrangement method for a coal-fired boiler under the condition of biomass co-firing. Summary of the Invention

[0008] In view of the above-mentioned deficiencies in the prior art, the present invention provides a burner arrangement method suitable for the operation condition of biomass co-firing in coal-fired boilers.

[0009] The technical solution of the present invention is: a burner arrangement method suitable for coal-fired boilers burning biomass, which is carried out according to the following steps:

[0010] Step 1: Add horizontal furnaces to the front and rear walls of the vertical furnace, with the two horizontal furnaces arranged opposite to the vertical furnace;

[0011] Step 2: Four biomass burners are installed on each of the two horizontal furnaces by cutting the four corners into circles, and the jet airflows in the two horizontal furnaces rotate in opposite directions;

[0012] Step 3: Install several pulverized coal burners on the front wall and the rear wall of the vertical furnace. The pulverized coal burners are arranged along the height direction of the vertical furnace and above the horizontal furnace.

[0013] Furthermore, the biomass burner is a direct current burner.

[0014] Furthermore, the pulverized coal burner is a swirl burner.

[0015] Compared with the prior art, the present invention has the following effects:

[0016] 1. Extending the biomass combustion path and ensuring complete burnout: The ingenious combination of a vertical and horizontal furnace significantly extends the biomass combustion path within the furnace. Biomass first enters the horizontal furnace, where it undergoes initial combustion using a direct current burner, generating a tangential flame. The spacious horizontal space provides a longer path for the biomass to move, significantly increasing its residence time within the furnace. This extended residence time increases the biomass's exposure to oxygen, allowing for a more complete combustion reaction, which plays a crucial role in ensuring complete burnout.

[0017] 2. Assists in the combustion of large proportions of biomass and ensures stable operation of the equipment: During the combustion process, the biomass is initially burned in the horizontal furnace, and the pulverized coal is transported to the vertical furnace through the pulverized coal burner for initial combustion. When burning biomass in large proportions, the pulverized coal and biomass each have independent air distribution systems; the independent air distribution systems and separate combustion areas enable the pulverized coal and biomass to independently organize the combustion process according to their own combustion needs, and there is no interference with each other in the initial combustion stage. In addition, a DC burner is used in the horizontal furnace for biomass combustion. In the case of large-proportion co-combustion, the unique structure of the DC burner can effectively slow down the slagging phenomenon, effectively ensuring the long-term stable operation of the burner. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention;

[0019] Figure 2 It is a structural schematic diagram of the pulverized coal burner 2 of the present invention;

[0020] Figure 3 It is a structural schematic diagram of the biomass burner 3 of the present invention;

[0021] Figure 4 yes Figure 1 Cross-sectional view in the A direction.

[0022] In the figure: 1. Vertical furnace; 2. Pulverized coal burner; 2-1. Pulverized coal primary air channel; 2-2. Pulverized coal secondary air channel; 2-3. Axial swirl blades; 3. Biomass burner; 3-1. Biomass primary air channel; 3-2. Biomass secondary air channel; 4. Horizontal furnace. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and through specific embodiments. Obviously, the embodiments described below are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Specific implementation method 1: Combination Figures 1 to 4 This embodiment is described as a burner arrangement method suitable for a coal-fired boiler that burns biomass. The method is specifically performed in the following steps:

[0025] Step 1: Add horizontal furnaces 4 to the front and rear walls of the vertical furnace 1. The two horizontal furnaces 4 are arranged opposite to the vertical furnace 1.

[0026] Step 2: Four biomass burners 3 are installed on each of the two horizontal furnaces 4 by cutting the four corners into circles, and the jet airflows in the two horizontal furnaces 4 rotate in opposite directions;

[0027] Step 3: Install several pulverized coal burners 2 on the front wall and the rear wall of the vertical furnace 1. The pulverized coal burners 2 are arranged along the height direction of the vertical furnace 1 and are arranged above the horizontal furnace 4.

[0028] Specific implementation method 2: Combination Figures 1 to 4 To explain this embodiment, the biomass burner 3 in this embodiment is a direct current burner.

[0029] Furthermore, the pulverized coal burner 2 is a swirl burner.

[0030] Other components and connection methods are the same as those in the first embodiment.

[0031] Specific implementation method three: Combination Figures 1 to 4 To illustrate this embodiment, the pulverized coal burner 2 in this embodiment includes a pulverized coal primary air channel 2-1 and a pulverized coal secondary air channel 2-2. The pulverized coal secondary air channel 2-2 is coaxially mounted on the pulverized coal primary air channel 2-1. A plurality of axial swirl blades 2-3 are installed in the pulverized coal secondary air channel 2-2 in a circular array.

[0032] Furthermore, the biomass burner 3 includes a biomass primary air channel 3-1 and a biomass secondary air channel 3-2; the biomass secondary air channel 3-2 is coaxially mounted on the biomass primary air channel 3-1.

[0033] Other components and connection methods are the same as those in the first or second embodiment.

[0034] Specific implementation method four: Combination Figures 1 to 4 To explain this embodiment, the cross section of the vertical furnace 1 in this embodiment is a square.

[0035] Furthermore, the longitudinal section of the horizontal furnace 4 is a square, and the biomass burners 3 are respectively installed at the four corners of the horizontal furnace 4.

[0036] Other components and connection methods are the same as those in the first, second or third embodiment.

[0037] Specific implementation method five: Combination Figures 1 to 4 In this embodiment, 10 to 30 pulverized coal burners 2 are installed on the front and rear walls of the vertical furnace 1. Other components and connection methods are the same as those of the first, second, third or fourth embodiments.

[0038] Specific implementation method six: combination Figures 1 to 4 To illustrate this embodiment, ten pulverized coal burners 2 are installed on both the front and rear walls of the vertical furnace 1. Other components and connection methods are the same as those of the first, second, third, fourth, or fifth embodiment.

[0039] Specific implementation method seven: combination Figures 1 to 4 This embodiment describes that 30 pulverized coal burners 2 are installed on the front and rear walls of the vertical furnace 1. Other components and connection methods are the same as those of the first, second, third, fourth, fifth or sixth embodiment.

[0040] How it works

[0041] During normal operation of the present invention, the pulverized coal burners 2 arranged on the front and rear walls of the vertical furnace 1 are used to organize the initial combustion of the pulverized coal. In the vertical furnace 1, the pulverized coal is gradually burned and eventually flows out from the furnace outlet.

[0042] The biomass burner 3 arranged in the horizontal furnace 4 is used to organize the initial combustion of biomass. The four-corner tangential circular arrangement of the biomass burner 3 allows the biomass to burn in a tangential circular flame, so that it is first fully burned in the horizontal furnace 4, and then enters the vertical furnace 1 from the outlet of the horizontal furnace 4 for further combustion until it is discharged from the outlet of the vertical furnace 1.

[0043] The present invention combines a vertical furnace 1 with a horizontal furnace 4, which greatly extends the combustion process of biomass in the furnace. In addition, when biomass is mixed and burned in a large proportion, the pulverized coal and biomass are each equipped with an independent air distribution system, and the initial combustion areas of the two are separated from each other, so that the pulverized coal and biomass can independently organize the combustion process according to their own combustion needs, and will not interfere with each other at all in the initial combustion stage. In addition, a DC burner is used for biomass combustion in the horizontal furnace. Since the outlet airflow of the DC burner exists in the form of a DC jet, this form of airflow will not produce rotation, thereby reducing the direct impact of the airflow on the furnace wall and reducing the possibility of coking; and the DC burner is arranged in a four-corner cut circle manner to avoid the flame directly impacting the furnace wall, thereby reducing the occurrence of coking. Therefore, in the case of large-scale mixing, the unique structure of the DC burner can effectively slow down the slagging phenomenon, effectively ensuring the long-term stable operation of the burner.

[0044] The present invention has been disclosed as above in terms of preferred embodiments, but this is not intended to limit the present invention. Any simple modifications, equivalent changes, and modifications made to the above implementation cases by any person skilled in the art without departing from the content of the technical solution of the present invention based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A burner arrangement method suitable for coal-fired boilers burning biomass, characterized by: The method proceeds as follows: Step 1: Adding horizontal furnaces (4) to the front wall and the rear wall of the vertical furnace (1), with the two horizontal furnaces (4) arranged opposite to the vertical furnace (1); Step 2: Four biomass burners (3) are installed on each of the two horizontal furnaces (4) by cutting the four corners into circles, and the jet airflows in the two horizontal furnaces (4) rotate in opposite directions; Step 3: Install a plurality of pulverized coal burners (2) on the front wall and the rear wall of the vertical furnace (1). The pulverized coal burners (2) are arranged along the height direction of the vertical furnace (1), and the pulverized coal burners (2) are arranged above the horizontal furnace (4).

2. A burner arrangement method for a biomass and coal mixed-firing boiler according to claim 1 is characterized in that: The biomass burner (3) is a direct current burner.

3. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 2, characterized in that: The pulverized coal burner (2) is a swirl burner.

4. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 1, characterized in that: The pulverized coal burner (2) comprises a pulverized coal primary air channel (2-1) and a pulverized coal secondary air channel (2-2). The pulverized coal secondary air channel (2-2) is coaxially sleeved on the pulverized coal primary air channel (2-1). A plurality of axial swirl blades (2-3) are installed in the pulverized coal secondary air channel (2-2) in a circumferential array.

5. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 4, characterized in that: The biomass burner (3) comprises a biomass primary air channel (3-1) and a biomass secondary air channel (3-2); the biomass secondary air channel (3-2) is coaxially sleeved on the biomass primary air channel (3-1).

6. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 1, characterized in that: The cross section of the vertical furnace (1) is square.

7. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 6, characterized in that: The longitudinal section of the horizontal furnace (4) is a square.

8. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 1, characterized in that: 10 to 30 pulverized coal burners (2) are installed on the front wall and the rear wall of the vertical furnace (1).

9. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 1, characterized in that: Ten pulverized coal burners (2) are installed on the front wall and the rear wall of the vertical furnace (1).

10. The burner arrangement method suitable for coal-fired boilers burning biomass according to claim 1, characterized in that: 30 pulverized coal burners (2) are installed on the front wall and the rear wall of the vertical furnace (1).

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