Pulverized coal doped coal bed gas turbulent burner

Abstract

The invention discloses a pulverized coal doped coal bed gas turbulent burner, and relates to the technical field of burners. The device comprises a rotational flow pulverized coal burner and a coal bed gas conveying pipeline, the coal bed gas conveying pipeline is a concentric circle pipe installed in a primary air pipe, and coal bed gas in the pipe is conveyed to an outlet of the primary air pipe to be sprayed out. The coal bed gas conveying pipeline is additionally arranged in the primary air pipe and used for ignition and stable combustion of pulverized coal under low load; the coal bed gas and the coal are combusted in a mixed mode, coal consumption is reduced, pollutant emission is reduced, the problem that pulverized coal is difficult to ignite under low load is solved, stable combustion of the pulverized coal can be achieved, and stable operation of a coal-fired unit is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of burners, and particularly relates to a pulverized coal-doped coalbed methane swirl burner. Background Art

[0002] Coalbed methane is an unconventional natural gas mainly composed of methane, which is mainly adsorbed in coal seams; the development and utilization of coalbed methane can not only provide clean energy, but also effectively reduce coal mine gas accidents and greenhouse gas emissions. Coalbed methane power generation, as one of the important ways of coalbed methane utilization, has received extensive attention in recent years; coalbed methane is a clean energy with a calorific value equivalent to that of natural gas, but its development is difficult. With the progress of coalbed methane development technology, the development potential of coalbed methane resources has been gradually released, providing an abundant fuel source for coalbed methane power generation; coalbed methane is the main component of coal mine gas, and its excessive concentration may cause safety accidents such as gas explosions; by developing coalbed methane, the concentration of coal mine gas can be effectively reduced, and the safety production level of coal mines can be improved.

[0003] With the progress of coalbed methane development technology, the development potential of coalbed methane resources has been gradually released, providing an abundant fuel source for coalbed methane power generation; after the coalbed methane is introduced into the pulverized coal boiler and ignites the pulverized coal, the pulverized coal can burn stably; coalbed methane combustion is an effective way of coalbed methane utilization. Coalbed methane is a gas with a relatively high calorific value per unit weight among known fuels, a high combustion speed, and a relatively high combustion temperature, and it is extremely prone to flashback and explosion. The main combustion characteristics of coalbed methane are as follows: 1) It is extremely easy to catch fire; 2) It has a high combustion speed, a concentrated combustion area, and a short flame; 3) The flame propagation speed of premixed combustion is very high, and the flashback problem is prominent during low-load operation; 4) The flame emissivity is low. In view of the above coalbed methane combustion characteristics, in this solution, the outlet of the coalbed methane delivery pipeline is clamped inside the primary air, and the flammable coalbed methane is used to heat the pulverized coal, providing sufficient guarantee for igniting the pulverized coal, so that the pulverized coal burns stably; based on the above solution, a pulverized coal-doped coalbed methane swirl burner is proposed. Summary of the Invention

[0004] The present invention provides a pulverized coal-doped coalbed methane swirl burner, in which the swirl pulverized coal burner and the coalbed methane delivery pipeline are arranged in parallel, the primary air pulverized coal delivery and the coalbed methane delivery are coordinated, and the coalbed methane in the furnace is ejected from the outlet of the coalbed methane delivery pipeline, which can enable the coalbed methane and coal to be mixed and burned, reducing both coal consumption and pollutant emissions, effectively utilizing the coalbed methane, and reducing carbon dioxide emissions.

[0005] To solve the above technical problems, the present invention is realized through the following technical solutions:

[0006] A pulverized coal-doped coalbed methane swirl burner of the present invention includes a pulverized coal swirl burner and a coalbed methane delivery pipeline;

[0007] The cyclone pulverized coal burner includes a primary air duct sleeved outside the coalbed methane conveying pipeline, an inner secondary air duct sleeved inside the primary air duct, an outer secondary air duct sleeved inside the inner secondary air duct, outer secondary air vanes circumferentially installed between the inner secondary air duct and the outer secondary air duct, and inner secondary air vanes installed in the inner secondary air duct; the inside of the primary air duct is a central air duct;

[0008] The primary air duct and the coalbed methane conveying pipeline are coaxially arranged, the outlet of the coalbed methane conveying pipeline is aligned with the outlet cross-section of the primary air duct, and the coalbed methane is ejected from the outlet of the coalbed methane conveying pipeline.

[0009] Further, both the outer secondary air vanes and the inner secondary air vanes are swirl vanes capable of forming a swirling air flow, and are installed on a circular rotating sleeve by welding or bolts.

[0010] Further, a coalbed methane storage device is connected to the inlet of the coalbed methane conveying pipeline, and a flow control system for adjusting the coalbed methane conveying flow rate is installed in the middle of the inlet of the coalbed methane conveying pipeline;

[0011] The flow control system includes a quick cut-off ball valve and a flow meter installed in the coalbed methane conveying pipeline, and the quick cut-off ball valve is controlled by a coalbed methane valve control unit capable of remote control.

[0012] Further, the primary air duct is of a circular tube type, and a concentrator with a variable cross-section is arranged inside. The outlet is a flared opening, which is used to convey the mixture of pulverized coal and hot air into the furnace and provide the fuel and part of the oxygen required for internal combustion.

[0013] Further, the inner secondary air duct and the outer secondary air duct are installed at the flared opening, which is used to stage-feed into the furnace interior to meet the remaining oxygen required for complete combustion of the pulverized coal.

[0014] Further, the concentrator is a constricted structure installed inside the primary air duct, which is used to concentrate the uniformly incoming pulverized coal air flow, so that the pulverized coal air flow undergoes concentration and dilution separation, enabling the pulverized coal to stably burn in the furnace

[0015] Further, the inner secondary air vanes are installed in the secondary air duct, which is used to deflect the flow direction of the secondary air flow and form a recirculation zone in the furnace.

[0016] The present invention has the following beneficial effects compared with the prior art:

[0017] (1) In this solution, a coalbed methane conveying pipeline is added inside the primary air duct, which is used for ignition and stable combustion of pulverized coal under low load, solves the problem of difficult ignition of pulverized coal under low load, and can also achieve stable combustion of pulverized coal, ensuring the stable operation of the coal-fired unit;

[0018] (2) This solution adds a coalbed methane transmission pipeline in the primary air duct, changes the fuel composition, lowers the overall ignition point, and solves the problem of difficulty in igniting coal powder under low load.

[0019] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 This is a schematic structural diagram of a cyclone burner of pulverized coal mixed with coal bed gas according to the present invention;

[0022] Figure 2 for Figure 1 A cross-sectional view of the middle burner from the rear side perspective;

[0023] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0024] 1- central air duct, 2- primary air duct, 3- coalbed methane transmission pipeline, 4- secondary air duct, 5- external secondary air duct, 6- internal secondary air blades, 7- external secondary air blades. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that the terms "outside", "inside", "center", "outlet", "cross-section", "coaxial" and the like indicating orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] Coalbed methane is a clean energy source with a calorific value comparable to that of natural gas, but it is difficult to develop. With the advancement of coalbed methane development technology, the development potential of coalbed methane resources has been gradually released, providing a sufficient fuel source for coalbed methane power generation. After the coalbed methane is introduced into the pulverized coal boiler, it ignites the pulverized coal, allowing the pulverized coal to burn stably.

[0028] Please refer to Figure 1-2 As shown, a pulverized coal blended with coalbed methane cyclone burner of the present invention includes a pulverized coal cyclone burner and a coalbed methane conveying pipeline 3;

[0029] The swirl pulverized coal burner includes a primary air duct 2 sleeved outside the coalbed methane conveying pipeline 3, an inner secondary air duct 4 sleeved inside the primary air duct 2, an outer secondary air duct 5 sleeved inside the inner secondary air duct 4, outer secondary air vanes 7 circumferentially installed between the inner secondary air duct 4 and the outer secondary air duct 5, and inner secondary air vanes 6 installed in the inner secondary air duct 4; inside the primary air duct 2 is a central air duct 1;

[0030] The primary air duct 2 and the coalbed methane conveying pipeline 3 are arranged in parallel, including the inner secondary air duct 4, the outer secondary air duct 5, the inner secondary air vanes 6, and the outer secondary air vanes 7; the cross-sectional area of the outlet of the coalbed methane blended burner in this solution is equal to the outlet cross-sectional area of the existing swirl pulverized coal burner, and the burning side is Figure 1 the left side of Figure 2 the right side of;

[0031] The secondary air vanes achieve the deflection of the air flow direction through their own shape design, which is a common technical means in swirl burners. The secondary air vanes are usually designed as curved airfoils or arc plates, and their cross-sectional shape is similar to that of an airplane wing. The bending angle and curvature of the vanes determine the direction and intensity of the air flow deflection. The installation angle of the vanes relative to the air flow direction (referred to as the angle of attack) is a key parameter. The common installation angle range is 30° to 60°, and the specific angle depends on the requirement of the swirl intensity.

[0032] A coalbed methane conveying pipeline 3 is added inside the primary air duct 2, and the cross-sectional area of the outlet of the new coalbed methane blended burner of the coalbed methane conveying pipeline is equal to the outlet cross-sectional area of the existing pulverized coal burner. The ignition position of the pulverized coal blended with coalbed methane cyclone burner in this solution is at the outlet of the burner; during boiler ignition and stable combustion, the coalbed methane blended in the burner can promptly ignite the pulverized coal. When the boiler is operating normally, the pulverized coal blended with coalbed methane cyclone burner has the functions of the original pulverized coal burner. At the same time, feeding coalbed methane into the pulverized coal boiler for combustion can stabilize the combustion and reduce carbon dioxide emissions. The present invention modifies the primary air duct of the swirl pulverized coal burner, and in parallel with the original burner, a coalbed methane conveying pipeline is installed to convey coalbed methane into the pulverized coal boiler, where the original burner is a swirl pulverized coal burner, and the structure of the pulverized coal burner publicly sold on the market or commonly used by those skilled in the art can be adopted.

[0033] Primary air refers to the air flow that carries coal powder into the burner. It is transported through the primary air duct to transport coal powder from the coal mill to the burner. The main function of primary air is to suspend and transport coal powder to ensure that coal powder enters the burner evenly. Secondary air refers to the combustion-supporting air flow that enters the burner through the secondary air duct. It does not carry coal powder and is mainly used to supplement the oxygen required for combustion. Through the swirl blades or swirlers, the secondary air forms a rotating airflow to enhance the mixing effect with the coal powder.

[0034] The primary air duct 2 and the coalbed methane delivery duct 3 are coaxially arranged, the outlet of the coalbed methane delivery duct 3 is aligned with the outlet section of the primary air duct 2, and the coalbed methane is ejected from the outlet of the coalbed methane delivery duct 3; a fluid passing through the coalbed methane is formed in the coalbed methane delivery duct 3, and the coalbed methane delivery duct is arranged parallel to the primary air duct. After the coalbed methane is ejected, it can be quickly ignited by the coal powder airflow ejected from the nozzle of the coal powder burner.

[0035] Among them, the outer secondary air blades 7 and the inner secondary air blades 6 are both swirl blades that can form a rotating airflow, and are installed on a circular rotating sleeve by welding or bolts; the blades are usually installed in the inner air duct of the burner, installed at the designated position of the inner air duct, and are usually fixed by bolts or welding. Of course, other forms of installation methods can achieve the effect of this scheme and belong to the protection scope of this scheme.

[0036] Among them, the inlet of the coalbed methane transmission pipeline 3 is connected to the coalbed methane storage equipment, and a flow control system for adjusting the coalbed methane transmission flow is installed in the middle of the inlet of the coalbed methane transmission pipeline 3; the flow control system includes a quick-cut ball valve and a flow meter installed in the coalbed methane transmission pipeline 3, and the quick-cut ball valve is controlled by a coalbed valve control unit that can be remotely controlled;

[0037] Due to the explosive nature of coalbed methane, a good safety mechanism needs to be established in the coalbed methane transportation system in front of the furnace, such as a quick-cut ball valve that automatically closes the valve when a power outage or compressed air failure occurs to ensure that the gas input is cut off; such as using a special pipeline flame arrester in front of the coalbed methane combustion head, which has outstanding explosion-proof and burning-resistant properties and small gas pressure loss.

[0038] Among them, the primary air duct 2 is a circular tube type, with a concentrator of variable cross-section arranged inside, and an expanded outlet, which is used to transport a mixture of coal powder and hot air into the furnace and provide the fuel and part of the oxygen required for internal combustion; the air supply duct itself is designed with a gradually contracting inlet section, a narrow throat in the middle section, and a gradually expanding outlet section, which is the concentrator.

[0039] Among them, the inner secondary air duct 4 and the outer secondary air duct 5 are installed at the expanded part, which are used to be sent into the furnace in stages to meet the remaining oxygen required for the complete combustion of the coal powder.

[0040] Among them, the concentrator is a constriction structure installed inside the primary air duct 2, which is used to concentrate the uniformly incoming pulverized coal air flow, so as to cause the concentration and dilution separation of the pulverized coal air flow, enabling the pulverized coal to burn stably in the furnace.

[0041] Among them, the inner secondary air vanes 6 are installed in the secondary air duct 4, which are used to deflect the flow direction of the secondary air flow and form a recirculation zone in the furnace.

[0042] To ensure the safety and reliability of the coalbed methane burner, equipment with auxiliary and detection functions needs to be installed on the basis of this system, including: (1) The coalbed methane ignition control system. All control signals and measuring points are directly connected to the DCS system, and the control and parameter display are carried out through the DCS system. The startup and operation of each system are controlled by its own local cabinet, and the local cabinet and the DCS transmit signals through the hard wiring of the terminal block. The ignition control has two operation modes: remote / local. Its changeover switch is set in the local control cabinet; (2) The image flame detection and monitoring system. To monitor the flame condition of the coalbed methane ignition burner and facilitate the combustion adjustment by the operation personnel, an image flame detection device is installed on each coalbed methane ignition combustion mechanism; (3) The on-line monitoring system for the wall temperature of the coalbed methane ignition combustion mechanism, which is displayed on the monitor of the DCS system, and the combustion adjustment is carried out in a timely manner according to the wall temperature condition.

[0043] The combustion of coalbed methane is an effective way of using coalbed methane. Coalbed methane is a gas with a relatively high calorific value per unit weight among known fuels, a high combustion speed, and a relatively high combustion temperature. It is extremely prone to flashback and explosion. The main combustion characteristics of coalbed methane are: 1) It is extremely easy to ignite; 2) It has a high combustion speed, a concentrated combustion area, and a short flame; 3) The flame propagation speed of premixed combustion is very high, and the flashback problem is prominent during low-load operation; 4) The flame emissivity is low; In view of the combustion characteristics of coalbed methane, the outlet of the coalbed methane delivery pipeline is arranged inside the primary air to heat the pulverized coal with the flammable coalbed methane, providing sufficient guarantee for igniting the pulverized coal, so as to enable the pulverized coal to burn stably.

[0044] According to the conventional commissioning method, the unit needs to operate at a low load for a long time during commissioning. During this period, the boiler burns only oil or a mixture of oil and coal. To avoid unburned oil droplets contaminating the electrodes, the boiler electrostatic precipitator cannot be normally put into operation, and a large amount of soot is directly discharged into the atmosphere, causing serious pollution to the environment. At the same time, the dust in the flue gas will cause abrasion to the blades of the boiler induced draft fan, all of which will bring indirect economic losses to the power plant.

[0045] When the coal seam gas pulverized coal ignition system is put into operation during the low-load stable combustion and start-stop of the unit, the electrostatic precipitator can be normally put into operation during the start-stop and low-load periods of the boiler, greatly reducing dust emissions, avoiding environmental pollution and wear of the induced draft fan, and bringing significant social and economic benefits to the power plant. Specifically, for the pulverized coal-blended coal seam gas swirl burner in this solution, a coal seam gas pipeline is added to the burner, realizing the combustion of coal seam gas blended with pulverized coal, reducing the overall ignition point, and achieving stable combustion at low loads. The power plant burns the coal seam gas and coal in combination, which not only reduces coal consumption but also reduces pollutant emissions. The power plant adopts a pure coal seam gas power generation mode with an installed capacity of 50 MW and an annual utilization of about 100 million cubic meters of coal seam gas. Through coal seam gas power generation, the power plant reduces coal consumption by about 100,000 tons per year and reduces carbon dioxide emissions by about 2 million tons per year.

[0046] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A cyclone burner of pulverized coal mixed with coal bed gas, characterized in that: It includes a pulverized coal swirl burner and a coalbed methane transmission pipeline (3); The swirl pulverized coal burner comprises a primary air duct (2) sleeved on the outside of a coalbed methane delivery duct (3), an inner secondary air duct (4) sleeved on the primary air duct (2), an outer secondary air duct (5) sleeved on the inner secondary air duct (4), an outer secondary air blade (7) installed around the inner secondary air duct (4) and the outer secondary air duct (5), and an inner secondary air blade (6) installed in the inner secondary air duct (4); the inner part of the primary air duct (2) is a central air duct (1); The primary air duct (2) and the coalbed methane delivery duct (3) are coaxially arranged, the outlet of the coalbed methane delivery duct (3) is aligned with the outlet cross section of the primary air duct (2), and the coalbed methane is ejected from the outlet of the coalbed methane delivery duct (3).

2. The cyclone burner of pulverized coal mixed with coal bed gas according to claim 1, characterized in that: The outer secondary air blades (7) and the inner secondary air blades (6) are both swirl blades capable of forming a swirling airflow, and are mounted on the circular rotating sleeve by welding or bolts.

3. The cyclone burner of pulverized coal mixed with coal bed gas according to claim 1, characterized in that: The inlet of the coalbed methane delivery pipeline (3) is connected to a coalbed methane storage device, and a flow control system for adjusting the coalbed methane delivery flow is installed in the middle of the inlet of the coalbed methane delivery pipeline (3); The flow control system comprises a quick-cut ball valve and a flow meter installed in a coal-bed methane transmission pipeline (3); the quick-cut ball valve is controlled by a coal-bed valve control unit capable of remote control.

4. The cyclone burner of pulverized coal mixed with coal bed gas according to claim 1, characterized in that: The primary air duct (2) is a circular tube, and is provided with a concentrator of variable cross-section inside. The outlet is expanded and is used to transport a mixture of coal powder and hot air into the furnace and provide the fuel and part of the oxygen required for internal combustion.

5. The cyclone burner of pulverized coal mixed with coal bed gas according to claim 4, characterized in that: An inner secondary air duct (4) and an outer secondary air duct (5) are installed at the expanded opening to deliver residual oxygen into the furnace in stages to meet the requirement for complete combustion of the pulverized coal.

6. The cyclone burner of pulverized coal mixed with coal bed gas according to claim 4, characterized in that: The concentrator is a constricted structure installed inside the primary air duct (2) and is used to concentrate the uniformly entering coal powder airflow, thereby causing the coal powder airflow to be separated into thick and thin parts, so that the coal powder can burn stably in the furnace.

7. The cyclone burner of pulverized coal mixed with coal bed gas according to claim 1, characterized in that: The inner secondary air blades (6) are installed in the secondary air duct (4) and are used to deflect the flow direction of the secondary air flow and form a reflow zone in the furnace.

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