A porous media coal burner for low volatile coal

Abstract

The present application relates to a kind of porous medium pulverized coal burner for low volatile coal, belong to pulverized coal combustion equipment technical field;Burner is sequentially arranged with primary air pipe, mixed combustion chamber, flow distribution plate along the direction of pulverized coal airflow flow, wherein primary air pipe is set at the entrance of mixed combustion chamber, flow distribution plate is set at the outlet of mixed combustion chamber, first porous medium layer and second porous medium layer are sequentially set on the side of flow distribution plate away from mixed combustion chamber, annular secondary air box is arranged outside second porous medium layer, a circle of secondary air nozzle is arranged on secondary air box, the direction of the spray of secondary air nozzle is towards the side away from mixed combustion chamber, and the direction of the spray of secondary air nozzle and the axial direction of mixed combustion chamber keep oblique angle;Using the strong heat storage capacity and heat conduction-radiation characteristics of porous solid medium, and supporting soot blowing device, activation wind device and other measures, realize that low volatile coal powder is reliable, stable, uniform, low NO x Original emission combustion.

Description

Technical Field

[0001] This invention belongs to the technical field of pulverized coal combustion equipment, specifically relating to a porous medium pulverized coal burner for low volatile coal. Background Technology

[0002] Porous media combustion technology is hailed by the international combustion community as "the latest generation of flameless combustion technology in the 21st century." Its core principle utilizes the heat storage capacity and thermal conductivity-radiation properties of porous solid media to transfer the high-temperature heat generated by combustion upstream through the media itself, preheating unburned fuel and forming a stable and uniform combustion source zone. This technology has been successfully applied in the field of low-calorific-value gaseous fuels, and operational practice has shown that it can extend the combustion limits of difficult-to-burn coals, increase combustion rate, enhance flame stability, and reduce NO. x Significant advantages such as emissions.

[0003] Compared to high-volatile bituminous coal, low-volatile lean coal and anthracite pulverized coal suffer from difficulties in ignition, poor combustion stability, and high NO content. x Addressing issues such as high initial displacement, applying porous media to pulverized coal burners is a crucial approach to resolving and improving the combustion characteristics of low-volatile pulverized coal. Current porous media combustion technologies are primarily limited to low-calorific-value gaseous fuels. For solid fuels like pulverized coal, the application of porous media combustion technology is limited due to issues such as ash and slag buildup during combustion clogging the micropores of the porous media and deposition during pulverized coal flow. Therefore, researching and developing a porous media pulverized coal burner for pulverized coal combustion is both important and necessary. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and proposes a porous media pulverized coal burner for low volatile coal; solving the problem of the current lack of a porous media pulverized coal burner for pulverized coal combustion.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution.

[0006] A porous media pulverized coal burner for low volatile coal includes a primary air duct, a mixing combustion chamber, and a flow equalization plate arranged sequentially along the pulverized coal airflow direction. The primary air duct is located at the inlet of the mixing combustion chamber, and the flow equalization plate is located at the outlet of the mixing combustion chamber. A first porous media layer and a second porous media layer are arranged sequentially on the side of the flow equalization plate away from the mixing combustion chamber. An annular secondary air box is arranged outside the second porous media layer. A ring of secondary air nozzles is arranged on the secondary air box. The secondary air nozzles are directed towards the side away from the mixing combustion chamber, and the direction of the secondary air nozzles is inclined at an angle to the axis of the mixing combustion chamber.

[0007] Furthermore, the mixing combustion chamber has a trumpet-shaped structure, and the inner diameter of the mixing combustion chamber gradually increases along the direction of pulverized coal airflow.

[0008] Furthermore, both the first and second porous dielectric layers are made of silicon carbide honeycomb ceramic porous dielectric, and both the first and second porous dielectric layers are covered with straight through holes that run straight along the axial direction.

[0009] Furthermore, the first porous medium layer serves as a preheating section, with a thickness of 60mm-80mm, a porosity designed to be 60%-70%, and a through-hole diameter of 3.0mm-4.0mm.

[0010] Furthermore, the second porous media layer serves as the main combustion section, with a thickness of 150mm-200mm, a porosity designed to be 70%-75%, and a through-hole diameter of 4.0mm-6.0mm.

[0011] Furthermore, a secondary air box inlet is provided on the side wall of the secondary air box.

[0012] Furthermore, an ignition vaporization oil gun is arranged on the upper side wall of the mixing combustion chamber to organize the combustion of the auxiliary fuel inside the mixing combustion chamber.

[0013] Furthermore, a soot blowing device is arranged on the upper side wall of the mixing combustion chamber. The soot blowing device is an acoustic soot blower that uses compressed air as a medium to periodically clean the coal ash particles in the first porous media layer and the second porous media layer.

[0014] Furthermore, an activation air device is arranged on the lower side wall of the mixing combustion chamber.

[0015] The beneficial effects of this invention compared to the prior art are as follows: This invention utilizes a through-hole porous medium made of silicon carbide in a low-volatile pulverized coal burner. By leveraging the strong heat storage capacity and thermal conductivity-radiation properties of the porous solid medium, and in conjunction with soot blowing and activation air devices, it achieves reliable, stable, uniform, and low-NOx production of low-volatile pulverized coal. x The combustion of raw emissions. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 yes Figure 1 View A in the middle; Among them, 1 is the primary air duct, 2 is the mixing combustion chamber, 3 is the flow equalization plate, 4 is the first porous medium layer, 5 is the second porous medium layer, 6 is the secondary air box inlet, 7 is the secondary air box, 8 is the secondary air nozzle, 9 is the ignition gasification oil gun, 10 is the soot blowing device, and 11 is the activation air device. Detailed Implementation

[0017] To make the technical problems to be solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail with reference to the embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of this invention are described in detail below with reference to the embodiments and accompanying drawings, but the scope of protection is not limited thereto.

[0018] like Figure 1 As shown in Figure 2, the present invention provides a porous medium pulverized coal burner for low volatile coal. The burner has a primary air duct 1, a mixing combustion chamber 2, and a flow equalization plate 3 arranged sequentially along the pulverized coal airflow direction. The primary air duct 1 is located at the inlet of the mixing combustion chamber 2, and the flow equalization plate 3 is located at the outlet of the mixing combustion chamber 2. A first porous medium layer 4 and a second porous medium layer 5 are arranged sequentially on the side of the flow equalization plate 3 away from the mixing combustion chamber 2. An annular secondary air box 7 is arranged outside the second porous medium layer 5. A ring of secondary air nozzles 8 is arranged on the secondary air box 7. The ejection direction of the secondary air nozzles 8 is towards the side away from the mixing combustion chamber 2, and the ejection direction of the secondary air nozzles 8 maintains an inclined angle with the axial direction of the mixing combustion chamber 2.

[0019] The mixing combustion chamber 2 has a trumpet-shaped structure, and the inner diameter of the mixing combustion chamber 2 gradually increases along the direction of coal powder airflow.

[0020] The flow equalization plate 3, the first porous medium layer 4, and the second porous medium layer 5 are all circular structures, and the axes of the primary air duct 1, the mixing combustion chamber 2, the flow equalization plate 3, the first porous medium layer 4, the second porous medium layer 5, and the secondary air box 7 are kept coincident.

[0021] Both the first porous dielectric layer 4 and the second porous dielectric layer 5 are made of silicon carbide honeycomb ceramic porous dielectric, with a heat resistance temperature of up to 1400℃. Both the first porous dielectric layer 4 and the second porous dielectric layer 5 are covered with straight through holes running axially.

[0022] The first porous medium layer 4 serves as a preheating section, with a thickness of 60mm-80mm, a porosity designed to be 60%-70%, and a through-hole diameter of 3.0mm-4.0mm.

[0023] The second porous medium layer 5 serves as the main combustion section, with a thickness of 150mm-200mm, a porosity designed to be 70%-75%, and a through-hole diameter of 4.0mm-6.0mm.

[0024] A secondary air box inlet 6 is provided on the side wall of the secondary air box 7. Secondary air is introduced into the secondary air box 7 through the secondary air box inlet 6. The secondary air introduced into the secondary air box 7 is ejected outward through a ring of secondary air nozzles 8. The ring of secondary air nozzles 8 is arranged in a circular array around the axis of the secondary air box 7. The ejection direction of the secondary air nozzles 8 is tilted to one side, and the ejection direction of the secondary air nozzles 8 maintains an angle of inclination with the axis of the mixing and combustion chamber 2, so that the secondary air ejected from the secondary air nozzles 8 forms a swirling jet.

[0025] An ignition gasification oil gun 9 and a soot blowing device 10 are arranged on the upper side wall of the mixing combustion chamber 2, and an activation air device 11 is arranged on the lower side wall of the mixing combustion chamber 2.

[0026] The combustion of the fuel oil is organized inside the mixing and combustion chamber 2 by igniting the vaporization oil gun 9.

[0027] The soot blowing device 10 is an acoustic soot blower that uses compressed air as a medium to periodically clean the coal ash particles in the first porous medium layer 4 and the second porous medium layer 5, ensuring the smooth flow of coal powder airflow.

[0028] The activation air device 11 is used to prevent coal powder from depositing at the bottom of the mixing combustion chamber 2 and to ensure that the coal powder airflow is evenly diffused inside the funnel-shaped mixing combustion chamber 2.

[0029] The flow equalization plate 3 is used to evenly distribute the pulverized coal airflow.

[0030] The working principle of this invention is as follows: First, the ignition gasification oil gun 9 is activated to form an initial high-temperature fire core inside the mixing combustion chamber 2, which preheats the first porous media layer 4 and the second porous media layer 5.

[0031] Once the temperature inside the mixing combustion chamber 2 reaches 1000℃, the primary air volume is gradually increased and pulverized coal is introduced. The primary air carrying pulverized coal flows through the primary air duct 1 into the mixing combustion chamber 2, and after being rectified by the flow equalization plate 3, it sequentially enters the first porous media layer 4 and the second porous media layer 5.

[0032] When the pulverized coal gas enters the first porous medium layer 4, the flow velocity is between 1.5 m / s and 2 m / s. Utilizing the strong thermal conductivity, radiation and heat storage characteristics of the first porous medium layer 4, the pulverized coal gas is rapidly heated to 1050℃-1150℃ in the preheating section, so that the pulverized coal gas has the conditions for ignition and combustion.

[0033] Subsequently, the pulverized coal gas flow enters the second porous media layer 5, with a flow velocity of 1.5 m / s to 2 m / s. The second porous media layer 5 serves as the main combustion section, utilizing the characteristics of the porous medium to organize the pulverized coal gas flow for effective, stable, and uniform combustion. The combustion temperature is controlled between 1050℃ and 1150℃. Due to the uniform combustion and controllable combustion temperature, the initial NO produced by the combustion of pulverized coal is minimized. x The porosity of the second porous media layer 5 is relatively low. While ensuring stable flame propagation and combustion, the larger porosity of the second porous media layer 5 reduces airflow resistance, ensuring that hot airflow and pulverized coal particles can pass smoothly through the second porous media layer 5 during pulverized coal combustion.

[0034] During operation, the combustion air enters the annular secondary air box 7 through the secondary air box inlet 6, and is then injected into the outlet of the second porous medium layer 5 through a ring of inclined secondary air nozzles 8, forming a strong swirling combustion flow field. The swirling secondary air is violently mixed with unburned coke particles at the outlet of the straight hole of the second porous medium layer 5. The central negative pressure backflow zone generated by the swirling flow draws the downstream high-temperature flue gas back to the outlet end face area of ​​the second porous medium layer 5, prolonging the flue gas residence time and enhancing heat feedback, thus ensuring the later-stage burnout of the coke and the combustion efficiency.

[0035] The soot blowing device 10 is operated periodically to clean coal ash particles from the first porous media layer 4 and the second porous media layer 5, preventing them from clogging the layers and ensuring smooth airflow for pulverized coal combustion. The activation air device 11 is put into operation as needed to agitate the bottom flow field, preventing pulverized coal from depositing at the bottom of the mixing combustion chamber 2. The flow equalization plate 3 is used to ensure that the pulverized coal airflow enters the first porous media layer 4 and the second porous media layer 5 evenly.

[0036] This invention utilizes a honeycomb ceramic porous medium made of silicon carbide to introduce the main body of the pulverized coal flame into the through-holes of the first porous medium layer 4 and the second porous medium layer 5 to complete preheating, ignition, and combustion. The through-hole structure physically avoids the problem of ash blockage. By leveraging the strong heat storage capacity and thermal conductivity-radiation properties of the honeycomb ceramic porous medium, it achieves a uniform, stable, and low-NOx combustion temperature of pulverized coal in the first and second porous medium layers 4 and 5, at 1050℃–1150℃. x The combustion of the original displacement, combined with the design of the swirling secondary air around the combustion zone of the second porous medium layer 5, ensures the burnout degree and combustion efficiency of pulverized coal.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A porous media pulverized coal burner for low-volatile coal, characterized in that: The burner is arranged in sequence along the flow direction of the pulverized coal airflow, including a primary air duct (1), a mixing combustion chamber (2), and a flow equalization plate (3). The primary air duct (1) is located at the inlet of the mixing combustion chamber (2), and the flow equalization plate (3) is located at the outlet of the mixing combustion chamber (2). On the side of the flow equalization plate (3) away from the mixing combustion chamber (2), a first porous media layer (4) and a second porous media layer (5) are arranged in sequence. An annular secondary air box (7) is arranged outside the second porous media layer (5). A ring of secondary air nozzles (8) is arranged on the box (7). The ejection direction of the secondary air nozzles (8) is towards the side away from the mixing combustion chamber (2), and the ejection direction of the secondary air nozzles (8) is inclined at an angle to the axial direction of the mixing combustion chamber (2). The first porous medium layer (4) and the second porous medium layer (5) are both made of silicon carbide honeycomb ceramic porous medium. The first porous medium layer (4) and the second porous medium layer (5) are covered with straight through holes that run straight along the axial direction.

2. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: The mixing combustion chamber (2) has a trumpet-shaped structure, and the inner diameter of the mixing combustion chamber (2) gradually increases along the direction of coal powder airflow.

3. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: The first porous medium layer (4) serves as a preheating section with a thickness of 60mm-80mm, a porosity of 60%-70%, and a through-hole diameter of 3.0mm-4.0mm.

4. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: The second porous medium layer (5) serves as the main combustion section, with a thickness of 150mm-200mm, a porosity of 70%-75%, and a diameter of 4.0mm-6.0mm for the through holes.

5. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: A secondary air box inlet (6) is provided on the side wall of the secondary air box (7).

6. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: An ignition gasification oil gun (9) is arranged on the upper side wall of the mixing combustion chamber (2) to organize the combustion of the auxiliary fuel inside the mixing combustion chamber (2).

7. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: A soot blowing device (10) is arranged on the upper side wall of the mixing combustion chamber (2). The soot blowing device (10) is an acoustic soot blower that uses compressed air as a medium to periodically clean the coal ash particles in the first porous medium layer (4) and the second porous medium layer (5).

8. A porous media pulverized coal burner for low-volatile coal according to claim 1, characterized in that: An activation air device (11) is arranged on the lower side wall of the mixing combustion chamber (2).

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