A snail-shaped element burner capable of igniting and burning steadily in the burner

Abstract

The present application provides a kind of snail shape primary combustor capable of igniting and burning in burner, including short cylindrical shell, high-temperature-resistant heat-insulating side cover, igniter, primary air pulverized coal gas flow injection inlet, arc bottom U-shaped expansion channel, wall surface necking pulverized coal concentration weir, flue gas and gasification gas outlet and base;The bottom of short cylindrical shell is base, and high-temperature-resistant heat-insulating side cover is arranged on one end surface of short cylindrical shell and connected therewith;Primary air pulverized coal gas flow injection inlet is arranged on one side of the bottom of the side of short cylindrical shell, and flue gas and gasification gas outlet is arranged on the other side of the bottom of the side;Wall surface necking pulverized coal concentration weir is arranged on the inner wall of short cylindrical shell on the side of primary air pulverized coal gas flow injection inlet, and arc bottom U-shaped expansion channel is arranged on the inner wall of short cylindrical shell on the side of flue gas and gasification gas outlet;Igniter is arranged at the outlet position of arc bottom U-shaped expansion channel.

Description

A snail-shaped element burner capable of stable ignition and combustion within the burner. Technical Field

[0001] This invention belongs to the technical field of pulverized coal burners, specifically relating to a snail-shaped element burner capable of stable ignition and combustion within the burner. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] As is well known, the combustion organization and ignition in a pulverized coal boiler are inseparable, both igniting at the burner outlet and then burning within the furnace (except for industrial pulverized coal combustion devices). Currently, pulverized coal boiler burners mainly fall into two categories: swirl burners and direct-flow burners. These two types of burners are essentially air-coal mixing injectors. Swirl burners rely on recirculation and reheat as the ignition heat source, and recirculation and reheat are one of the core issues in swirl burner stable combustion technology. Direct-flow burners with a tangential combustion method rely on the upstream rotating flame merging with primary air as the ignition source. Flame temperature and mixing volume are among the core issues for stable combustion in direct-flow burners.

[0004] The difficulty in controlling the reflux heat and upstream flame supply has become a constraint on the stable combustion of pulverized coal boilers under low load. Currently, most power plant units above 300MW use pulverized coal boilers. To adapt to the highly volatile and intermittent characteristics of new energy power generation such as wind power and solar photovoltaic power, the flexibility and peak-shaving capability of coal-fired power plant units have become a problem that must be solved. Under low load, the temperature level inside the furnace of a pulverized coal boiler decreases, the reflux heat weakens, the ignition conditions deteriorate, or even fail to meet the ignition conditions, making stable operation difficult and even causing boiler shutdown.

[0005] Under the policy of flexibly retrofitting existing coal-fired power units, the original combustion technology is insufficient to guarantee stable operation of boilers without oil injection during deep peak shaving. To achieve stable combustion without oil injection at low loads, the current conventional approach is to modify the boiler burners. Burner modification technologies include plasma ignition technology, micro-oil ignition technology, and oxygen-enriched ignition technology.

[0006] Plasma ignition retrofit technology requires continuous arcing operation when the boiler is at low load, consuming electrical energy; and it is not suitable for bituminous coal with volatile matter content below 20%. Micro-oil ignition technology requires long-term oil injection during normal operation, resulting in high operating costs and failing to meet the dual carbon reduction targets of energy conservation and emission reduction.

[0007] The flexibility and peak-shaving capability of pulverized coal boilers in power plants is actually a problem of stable combustion under low load. The two existing mainstream burners cannot achieve stable operation below 30% boiler load. Furthermore, there are many problems with the technology for modifying existing burners. Therefore, inventing a new type of burner suitable for low-load operation of pulverized coal boilers has become an urgent issue to be addressed. Summary of the Invention

[0008] The purpose of this invention is to provide a snail-shaped element burner that can be ignited and stably burned inside the burner. The snail-shaped element burner is an independent device installed outside the furnace and is circular, near-circular, or volute-shaped.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0010] Embodiments of the present invention provide a snail-shaped element burner capable of stable combustion and ignition within the burner, comprising a short cylindrical shell, a high-temperature resistant heat-insulating side cover, an igniter, a primary air pulverized coal gas flow injection inlet, an arc-bottom U-shaped expansion channel, a wall-constricted pulverized coal concentration weir, a flue gas and gasification gas outlet, and a base.

[0011] The bottom of the short cylindrical shell is a base, and a high-temperature resistant heat-insulating side cover connected to one end face of the short cylindrical shell is provided; a primary air pulverized coal airflow injection inlet is provided on one side of the bottom side of the short cylindrical shell, and a flue gas and gasification gas outlet is provided on the other side of the bottom side.

[0012] A coal powder thickening weir with a narrowed wall is set on the inner wall of the short cylindrical shell on the side of the primary air pulverized coal gas injection inlet, and an arc-bottomed U-shaped expansion channel is set on the inner wall of the short cylindrical shell on the side of the flue gas and gasification gas outlet.

[0013] An igniter is installed at the exit position of the U-shaped expansion channel at the bottom of the arc.

[0014] The working principle of the snail-shaped element burner proposed in this invention is as follows: the primary air pulverized coal gas flow is tangentially injected at high speed into a circular, near-circular, or volute-shaped cavity and forms a swirling air flow. At the inlet, the cold pulverized coal gas flow and the high-temperature combustion (gasification) gas flow have sufficient mixing conditions, obtain ignition heat, and reach the ignition temperature. At the same time, a stable high-temperature flame low-speed rotating air flow is formed in the center of the cavity. This air flow continuously delivers heat to the cold pulverized coal gas flow and is continuously replenished from the ignition gas flow, thereby enabling the snail-shaped element burner to operate stably.

[0015] As a further technical solution, the arc-bottom U-shaped expansion channel is composed of an equal-width arc-bottom U-shaped section, an expansion arc-bottom U-shaped section, and positioning strips at both ends; the U-shaped opening of the equal-width arc-bottom U-shaped section is directly opposite to the primary air pulverized coal airflow injection inlet, and the back side of the equal-width arc-bottom U-shaped section is directly opposite to the flue gas and gasification gas outlet.

[0016] As a further technical solution, the positioning strip engages with the groove at the corresponding position on the inner wall of the short cylindrical shell to fix the component in place within the burner, which also facilitates later maintenance or replacement.

[0017] As a further technical solution, the wall-narrowed coal powder thickening weir is located next to the upper edge of the primary air coal powder airflow injection inlet. It is a U-shaped arc-bottom channel that gradually narrows from top to bottom, cast with refractory and wear-resistant castable. The width of its lower end is equal to the width of the primary air coal powder airflow injection inlet. Its function is to concentrate the high-temperature coal powder flowing along the inner circumference of the short cylindrical shell due to centrifugal force to the middle position and directly mix it into the cold primary air to achieve mass return and heat transfer.

[0018] As a further technical solution, the short cylindrical shell comprises multiple layers, which, from the inner layer to the outer layer, are successively a refractory and wear-resistant castable layer, a heat-insulating castable layer, an aluminum silicate fiber blanket, and a carbon steel outer shell.

[0019] As a further technical solution, the high-temperature resistant heat-insulating side cover is welded from a carbon steel flange plate and a high-temperature resistant stainless steel short cone.

[0020] As a further technical solution, the high-temperature resistant stainless steel short cone consists of a fire-resistant and wear-resistant castable layer, a heat-insulating castable layer, and an aluminum silicate fiber blanket, from the inner layer to the outer layer.

[0021] As a further technical solution, a high-temperature resistant sealing gasket is placed between the short cylindrical shell and the high-temperature resistant heat-insulating side cover, and the seal is achieved by fastening with fasteners to form the sealed cavity of the present invention.

[0022] As a further technical solution, the high-temperature resistant sealing gasket material is aluminum silicate fiber paper or other heat-resistant materials.

[0023] As a further technical solution, the primary air pulverized coal gas injection inlet includes a standard flange, a round-to-square reduced-length section, and a square tube connected in sequence.

[0024] As a further technical solution, the snail-shaped element burner can be installed independently outside the pulverized coal boiler, or near the existing burner, serving as a bypass for the primary air duct. This invention is activated when the boiler is under low load and deactivated when the boiler is under high load. It can also directly replace the existing burner in the pulverized coal boiler.

[0025] Snail-shaped element burners can also be used for other powdery solid or liquid fuels other than pulverized coal.

[0026] The beneficial effects of this invention are as follows:

[0027] The snail-shaped element burner truly realizes combustion within the burner, decoupled from combustion in the furnace, and is not affected by combustion or load in the furnace. The snail-shaped element burner can be set up independently, igniting the pulverized coal before sending it into the boiler.

[0028] When flexibly retrofitting a pulverized coal boiler for thermal power, the retrofit can be completed simply by connecting a bypass pipe to the corresponding inlet and outlet of the device of this invention at an appropriate position in the primary air duct before the original burner, without any other modifications to the boiler. The retrofit is minimal in workload, low in cost, highly adaptable, and low in risk. When the boiler is running at 40%-100% BMCR, the switching valve before the snail-shaped element burner only needs to be closed, which has no negative impact on the normal operation of the boiler and can achieve stable operation of the boiler at ultra-low load.

[0029] This invention can increase the temperature of primary air pulverized coal flow to 900-1200℃. This high-temperature primary air is mixed into the burner or directly introduced into the boiler furnace and mixed with oxygen-enriched secondary air, which is beneficial to the ignition of pulverized coal, thereby achieving stable operation of the boiler at 10%-30% BMCR load.

[0030] This invention does not require electricity or other forms of energy during operation; instead, it provides heat by burning a portion of the pulverized coal in the primary air supply. Therefore, it has the advantages of a simple system and low initial investment and operating costs. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 is a schematic diagram of the structure of the snail-shaped element burner of the present invention;

[0033] Figure 2 is a cross-sectional view AA of Figure 1;

[0034] Figure 3 is a view from direction B in Figure 1;

[0035] Figure 4 is a view from direction C in Figure 1;

[0036] Figure 5 is a schematic diagram of the short cylindrical shell structure;

[0037] Figure 6 is a DD cross-sectional view of Figure 5;

[0038] Figure 7. Schematic diagram of the arc-bottom U-shaped expansion channel structure;

[0039] Figure 8 is the right view of Figure 7;

[0040] Figure 9 is a cross-sectional view of EE in Figure 7;

[0041] Figure 10 is a schematic diagram of the primary air pulverized coal gas jet inlet structure;

[0042] Figure 11 is a schematic diagram of the high-temperature resistant heat-insulating side cover structure;

[0043] The components include: 1. Short cylindrical shell; 1-1. Axial rectangular groove; 1-2. Carbon steel shell; 1-3. Alumina silicate fiber blanket; 1-4. Thermal insulation castable layer; 1-5. Refractory and wear-resistant castable layer; 2. Igniter; 3. U-shaped expansion channel with arc bottom; 3-1. U-shaped section with equal width arc bottom; 3-2. U-shaped section with expansion arc bottom; 3-3. Rectangular positioning strip; 4. Instrument pipe seat; 5. Flue gas and gasified gas outlet; 6. Base; 7. Primary air pulverized coal airflow injection inlet; 7-1. Standard flange; 7-2. Round-to-square reduced-neck short section; 7-3. Square tube; 8. Wall-reduced pulverized coal thickening weir; 9. High-temperature resistant thermal insulation side cover; 9-1. Carbon steel flange plate; 9-2. High-temperature resistant stainless steel short cone; 9-3. Alumina silicate fiber blanket; 9-4. Thermal insulation castable layer; 9-5. Refractory and wear-resistant castable layer. Detailed Implementation

[0044] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0045] Example 1

[0046] In a typical embodiment of the present invention, as shown in Figures 1 and 2, a snail-shaped element burner is provided. It is a short cylindrical burner that is detachable, allowing for the complete replacement of the core components and facilitating the inspection and maintenance of all internal parts. Specifically, it includes a short cylindrical shell 1, a high-temperature resistant heat-insulating side cover 9, an igniter 2, a primary air / coal powder gas injection inlet 7, an arc-bottom U-shaped expansion channel 3, a coal powder concentration weir with a narrowed wall 8, a flue gas and gasification gas outlet 5, an instrument pipe seat 4, and a base 6, etc.

[0047] The bottom of the short cylindrical shell 1 is provided with a base 6, and a high-temperature resistant heat-insulating side cover 9 is provided on one end face of the short cylindrical shell 1. The high-temperature resistant heat-insulating side cover 9 is connected to the short cylindrical shell 1. A primary air coal powder airflow injection inlet 7 is provided on one side of the bottom of the side of the short cylindrical shell 1, and a flue gas and gasification gas outlet 5 is provided on the other side of the bottom of the side.

[0048] A coal powder thickening weir 8 with a narrowed wall is provided on the inner wall of the short cylindrical shell 1 on the side of the primary air coal powder injection inlet 7, and an arc-bottomed U-shaped expansion channel 3 is provided on the inner wall of the short cylindrical shell 1 on the side of the flue gas and gasification gas outlet 5.

[0049] Ignition device 2 is installed at the exit position of the U-shaped expansion channel 3 at the bottom of the arc.

[0050] As shown in Figure 5, the short cylindrical shell 1 has a multi-layer structure, consisting of a refractory and wear-resistant castable layer 1-5, a heat-insulating castable layer 1-4, an aluminum silicate fiber blanket 1-3, and a carbon steel outer shell 1-2, from the inner layer to the outer layer.

[0051] As shown in Figure 6, two axial rectangular grooves 1-1 cast from refractory and wear-resistant castable are provided at corresponding positions on the inner wall of the short cylindrical shell. These axial rectangular grooves 1-1 are used to install the arc-bottom U-shaped expansion channel 3.

[0052] As shown in Figure 11, the high-temperature resistant heat-insulating side cover 9 is welded together from a carbon steel flange plate 9-1 and a high-temperature resistant stainless steel short cone 9-2 disposed on the inner side of the carbon steel flange plate 9-1. The same refractory material as the short cylindrical shell 1 is cast inside the high-temperature resistant stainless steel short cone 9-2. Specifically, the high-temperature resistant stainless steel short cone 9-2 consists of a fire-resistant and wear-resistant castable layer 9-5, a heat-insulating castable layer 9-4, and an aluminum silicate fiber blanket 9-3, from the inner layer to the outer layer.

[0053] As shown in Figure 2, a high-temperature resistant sealing gasket is placed between the short cylindrical shell 1 and the high-temperature resistant heat-insulating side cover 9, and the sealing is achieved by fastening with fasteners to form the sealed cavity of the present invention; furthermore, the high-temperature resistant sealing gasket is made of aluminum silicate fiber paper or other heat-resistant materials.

[0054] Furthermore, the igniter 2 can be in the form of an oil gun igniter, a natural gas igniter, or a plasma igniter; as shown in Figure 1, in this embodiment, the igniter 2 is set above the arc-bottom U-shaped expansion channel 3.

[0055] As shown in Figure 10, the primary air pulverized coal gas injection inlet 7 in this embodiment includes a standard flange 7-1, a round-to-square tapered short section 7-2, and a square tube 7-3 connected in sequence. These are welded to the inlet position reserved on the short cylindrical shell 1. The primary air pulverized coal gas injection inlet 7 is a channel where a round tube is tapered into a rectangular tube to facilitate the high-speed injection of primary air into the snail-shaped element burner. The standard flange 7-1 is used for connection with other devices. The round-to-square tapered short section 7-2 makes the pulverized coal gas flow form a high-speed injection shape. The centerline of the primary air pulverized coal gas injection inlet 7 is a horizontal straight line, and the pulverized coal gas flow enters the short cylindrical shell 1 in a horizontal direction.

[0056] As shown in Figures 1, 2, 7, 8, and 9, the arc-bottom U-shaped expansion channel 3 is the core component of this invention, consisting of a uniform-width arc-bottom U-shaped section 3-1, an expanding arc-bottom U-shaped section 3-2, and rectangular positioning strips 3-3 at both ends. The front U-shaped opening of the uniform-width arc-bottom U-shaped section 3-1 is directly opposite the primary air pulverized coal airflow injection inlet 7, allowing the pulverized coal airflow entering from the primary air pulverized coal airflow injection inlet 7 to enter the arc-bottom U-shaped expansion channel 3. As shown in Figure 4, the back of the uniform-width arc-bottom U-shaped section 3-1 is directly opposite the flue gas and gasification gas outlet 5, thus forming a U-shaped channel where cold primary air mainly flows, while high-temperature combustion flue gas (gasification gas) flows on both sides and the back. In this embodiment, this part... This structural design and positioning achieves the convergence and mixing of hot and cold airflows and hot and cold pulverized coal. At this location, low-temperature primary air is injected at high speed into the surrounding high-temperature flue gas (gasification gas) and hot pulverized coal, while high-temperature flue gas (gasification gas) carries high-temperature pulverized coal and pushes cold primary air. This provides a high-temperature environment and sufficient heat for stable combustion (gasification) of primary air, thereby achieving stable combustion (gasification) of primary air pulverized coal. The rectangular positioning strip 3-3 cooperates with the axial rectangular groove 1-1 at the corresponding position on the inner wall of the short cylindrical shell to fix the component in place in the burner, and facilitates later maintenance or replacement. The component can be made of high-temperature resistant stainless steel, corundum, ceramic, or silicon carbide, etc., which are heat-resistant and wear-resistant materials.

[0057] In a further preferred embodiment, the central angle of the arc-bottom U-shaped expansion channel 3 is 90°, as shown in Figure 1.

[0058] As shown in Figures 1 and 3, the wall-narrowed coal powder thickening weir 8 is a U-shaped arc-bottomed channel that gradually narrows from top to bottom, cast from refractory and wear-resistant castable, located immediately adjacent to the upper edge of the primary air coal powder jet inlet 7. The lower width of the U-shaped arc-bottomed channel is equal to the width of the primary air coal powder jet inlet 7. Its function is to concentrate the high-temperature coal powder flowing along the inner circumference of the short cylindrical shell 1 due to centrifugal force to the middle position and directly mix it with the cold primary air, thereby achieving mass return and heat transfer. Furthermore, the wall-narrowed coal powder thickening weir 8 can be cast together with the innermost layer of the short cylindrical shell 1.

[0059] As shown in Figure 1, the flue gas and gasification gas outlet 5 is located opposite the primary air pulverized coal airflow injection inlet 7 and serves as the outlet channel for flue gas and gasification gas. The flue gas and gasification gas outlet 5 is horizontally positioned, and the material layer of the flue gas and gasification gas outlet 5 is the same as that of the short cylindrical shell 1. A connecting flange is also provided on the end face of the flue gas and gasification gas outlet 5.

[0060] Furthermore, the instrument tube seat 4 is installed at the corresponding position and inserted into the internal port of the snail-shaped burner for installing some instruments.

[0061] The snail-shaped element burner proposed in this embodiment truly achieves combustion within the burner, decoupled from combustion in the furnace, and unaffected by combustion or load in the furnace. The snail-shaped element burner ignites the pulverized coal before sending it into the boiler. When flexibly retrofitting a pulverized coal boiler, the modification can be completed simply by connecting a bypass pipe to the corresponding inlet and outlet of the device of this invention at an appropriate location in the primary air duct before the original burner, without requiring any other modifications to the boiler. The modification workload is small, the cost is low, the adaptability is strong, and the risk is low. When the boiler is operating at 40%-100% BMCR, simply closing the switching valve before the snail-shaped element burner is sufficient, without any negative impact on the normal operation of the boiler, enabling stable operation of the boiler at ultra-low loads.

[0062] The burner proposed in this embodiment can increase the temperature of the primary air pulverized coal flow to 900-1200℃. This high-temperature primary air, when mixed into the burner or directly introduced into the boiler furnace and mixed with the oxygen-enriched secondary air, is beneficial to the ignition of pulverized coal, thereby achieving stable operation of the boiler at 10%-30% BMCR load.

[0063] The burner proposed in this embodiment does not consume electricity or other forms of energy during operation; instead, it provides heat by burning a portion of the pulverized coal in the primary air. Therefore, it has the advantages of a simple system and low initial investment and operating costs.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A snail-shaped element burner capable of stable combustion upon ignition within the burner, characterized in that; The system includes a short cylindrical shell, a high-temperature resistant insulated side cover, an igniter, a primary air / pulverized coal gas injection inlet, an arc-bottomed U-shaped expansion channel, a coal gas concentration weir with a narrowed wall, flue gas and gasification gas outlets, and a base. The bottom of the short cylindrical shell is the base, and a high-temperature resistant insulated side cover is connected to one end face of the short cylindrical shell. A primary air / pulverized coal gas injection inlet is located on one bottom side of the short cylindrical shell, and a flue gas and gasification gas outlet is located on the other bottom side. A pulverized coal thickening weir with a narrowed wall is provided on the inner wall of the short cylindrical shell on the injection inlet side, and an arc-bottomed U-shaped expansion channel is provided on the inner wall of the short cylindrical shell on the flue gas and gasification gas outlet side; the pulverized coal thickening weir with a narrowed wall is close to the upper edge of the primary air pulverized coal gas injection inlet, and the U-shaped arc-bottomed channel with a gradually narrowing opening from top to bottom is cast by refractory and wear-resistant castable, and the width of its lower end is equal to the width of the primary air pulverized coal gas injection inlet; an igniter is provided at the outlet position of the arc-bottomed U-shaped expansion channel.

2. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 1, characterized in that, The arc-bottom U-shaped expansion channel consists of an equal-width arc-bottom U-shaped section, an expansion arc-bottom U-shaped section, and positioning strips at both ends; the U-shaped opening of the equal-width arc-bottom U-shaped section is directly opposite to the primary air pulverized coal airflow injection inlet, and the back side of the equal-width arc-bottom U-shaped section is directly opposite to the flue gas and gasification gas outlet.

3. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 2, characterized in that, The positioning strip engages with the groove at the corresponding position on the inner wall of the short cylindrical shell.

4. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 1, characterized in that, The short cylindrical shell comprises multiple layers, which, from the innermost layer to the outermost layer, are a refractory and wear-resistant castable layer, a heat-insulating castable layer, an aluminum silicate fiber blanket, and a carbon steel outer shell.

5. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 1, characterized in that, The high-temperature resistant heat-insulating side cover is welded from a carbon steel flange plate and a high-temperature resistant stainless steel short cone.

6. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 5, characterized in that, The high-temperature resistant stainless steel short cone consists of, from the innermost layer to the outermost layer, a fire-resistant and wear-resistant castable layer, a heat-insulating castable layer, and an aluminum silicate fiber blanket.

7. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 1, characterized in that, A high-temperature resistant sealing gasket is placed between the short cylindrical shell and the high-temperature resistant heat-insulating side cover, and the seal is achieved by fastening with fasteners, forming the sealed cavity of the present invention.

8. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 1, characterized in that: The primary air pulverized coal gas injection inlet comprises a standard flange, a round-to-square reduced-length section, and a square tube connected in sequence.

9. The snail-shaped element burner capable of stable combustion and ignition within the burner as described in claim 1, characterized in that, The snail-shaped burner is installed independently outside the pulverized coal boiler, and it can also be used for the combustion of other powdery solid or liquid fuels other than pulverized coal.

Images