High-temperature liquid slagging burner suitable for strongly-slagging high-alkali coal and burning method

Abstract

The invention discloses a high-temperature liquid slagging burner suitable for strong slagging high-alkali coal and a burning method, and relates to the technical field of coal burning equipment.The high-temperature liquid slagging burner comprises an adiabatic high-temperature cyclone burning pre-burning chamber, an adiabatic lower slagging chamber, a slag catching screen and a water-cooled wall type upper slagging chamber, and the pre-burning chamber is provided with a pulverized coal cyclone burner and a high-speed secondary air inlet; the bottom of the lower deslagging chamber is provided with a liquid deslagging port, the slag catching screen is arranged between the lower deslagging chamber and the upper deslagging chamber, the upper deslagging chamber is provided with a high-temperature hot flue gas inlet, and an outlet of the high-temperature hot flue gas inlet is communicated with a boiler hearth. A liquid slag film is formed through strong rotational flow high-temperature combustion in the pre-combustion chamber to capture coke / semicoke / fly ash particles and achieve secondary combustion, secondary slag capturing is conducted through the slag capturing screen, 85%-90% of coal ash is molten and discharged, only 10%-15% of fly ash enters a hearth, the technical problems that strong slagging high-alkali coal cannot be fully burnt, and the heating surface of the tail of the boiler is severely contaminated are thoroughly solved, and the energy-saving and environment-friendly high-alkali coal boiler is suitable for large-scale industrial production. Meanwhile, the combustion efficiency is improved, the energy consumption is reduced, and the industrial application value is remarkable.

Description

Technical Field

[0001] This invention relates to the field of coal combustion equipment technology, specifically to a combustion treatment device and supporting combustion method for highly slagging and high-alkali coal. It is particularly suitable for the efficient and clean combustion of high-iron and high-alkali coal types with abundant reserves in Xinjiang and other regions, and can be widely used in coal-fired equipment such as power plant boilers and industrial boilers. Background Technology

[0002] my country's energy structure is dominated by coal, among which high-alkali coal is an important coal resource with huge reserves in regions such as Xinjiang. Its development and utilization are of great significance for ensuring national energy security and optimizing the energy layout. High-alkali coal generally refers to coal with a high content of alkali metals (sodium, potassium, etc.). Some high-alkali coals also have high iron content. This type of coal is prone to slagging and fouling problems during combustion, posing a serious challenge to conventional combustion equipment.

[0003] Conventional coal-fired equipment mostly employs solid-state ash discharge combustion. In this method, when burning highly ash-caking, high-alkali coal, the low-melting components in the coal easily condense and adhere to the furnace heating surfaces and convective heating surfaces, forming a hard ash layer and fouling layer. On the one hand, ash and fouling significantly reduce the heat transfer efficiency of the heating surfaces, lowering boiler thermal efficiency and increasing energy consumption. On the other hand, severe ash buildup can clog furnace passages, flues, and air preheaters, affecting normal boiler operation and even triggering shutdowns for maintenance, significantly increasing operating and maintenance costs. More importantly, conventional solid-state ash discharge combustion cannot achieve complete combustion of highly ash-caking, high-alkali coal, usually requiring blending with low-alkali coal. This not only limits the utilization rate of high-alkali coal resources but also increases coal transportation and allocation costs, hindering the large-scale development and utilization of high-alkali coal.

[0004] To address the slagging problem during the combustion of high-alkali coal, the industry has proposed liquid ash discharge combustion technology. The core idea is to raise the combustion temperature above the coal ash melting temperature, allowing the coal ash to be discharged in liquid form, thereby reducing slagging on the heating surfaces. However, existing liquid ash discharge combustion equipment still suffers from several technical shortcomings: some equipment has poor insulation in the pre-combustion chamber, making it difficult to maintain a stable high-temperature combustion environment, resulting in insufficient melting of low-melting-point components in the coal and a low liquid ash discharge rate; some equipment lacks efficient ash-catching structures, allowing large amounts of sticky ash carried in the flue gas at the pre-combustion chamber outlet to still enter the subsequent furnace and tail heating surfaces, causing secondary fouling; and some equipment exhibits unstable slag film formation, easily leading to slag film detachment or blockage of the ash discharge channels, affecting the continuity and safety of the combustion process. Furthermore, existing liquid ash discharge technology has poor adaptability to strongly slagging high-alkali coal, making it difficult to balance overall combustion effect, ash-catching efficiency, and combustion stability, thus failing to meet the needs of large-scale industrial applications.

[0005] Therefore, developing a high-efficiency, stable, and low-fouling high-temperature liquid ash discharge combustion equipment and method suitable for strongly slagging and high-alkali coal has become an urgent technical problem to be solved in the field of coal combustion. Summary of the Invention

[0006] In view of the above-mentioned defects in the prior art, the present invention aims to solve the technical problems of the prior art, such as the difficulty in fully burning strongly slagging high-alkali coal, serious slagging and fouling during the combustion process, low slag removal efficiency of liquid slag discharge equipment, and poor operational stability. The present invention provides a high-temperature liquid slag discharge burner and combustion method suitable for strongly slagging high-alkali coal, so as to realize the full combustion and utilization of strongly slagging high-alkali coal, significantly reduce the risk of fouling of the boiler tail heating surface, and at the same time ensure the high efficiency and stability of the combustion process.

[0007] To achieve the above objectives, the present invention provides a high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal, comprising a high-temperature cyclone combustion pre-combustion chamber, a lower ash discharge chamber, a ash trap, and an upper ash discharge chamber; the high-temperature cyclone combustion pre-combustion chamber is an insulated structure, equipped with a pulverized coal cyclone burner and a high-speed secondary air inlet; the lower ash discharge chamber is an insulated structure, its top connected to the outlet of the high-temperature cyclone combustion pre-combustion chamber, and its bottom provided with a liquid ash discharge port; the ash trap is disposed between the lower ash discharge chamber and the upper ash discharge chamber, used to capture sticky ash in the flue gas; the upper ash discharge chamber is a water-cooled wall structure, equipped with a high-temperature hot flue gas inlet, and its outlet connected to the boiler furnace.

[0008] Preferably, the inner wall of the high-temperature cyclone combustion pre-combustion chamber is provided with a high-temperature resistant insulation layer, which is made of ceramic fiber composite material.

[0009] Preferably, the high-speed secondary air inlet is uniformly arranged along the circumference of the high-temperature cyclone combustion pre-combustion chamber, and the inlet axis is at a preset angle to the central axis of the high-temperature cyclone combustion pre-combustion chamber to form a strong swirling flow field.

[0010] Preferably, the slag trap has a finned structure, with the fins arranged in a staggered pattern along the flue gas flow direction, and the surface of the fins is coated with a high-temperature resistant coating.

[0011] Preferably, the inner wall of the lower slag discharge chamber is provided with an anti-wear lining, and the liquid slag discharge port is equipped with a controllable slag discharge valve for adjusting the discharge rate of the liquid slag.

[0012] Preferably, the water-cooled wall of the upper slag discharge chamber adopts a membrane wall structure, and a cooling medium flows inside the water-cooled wall to moderately cool the high-temperature flue gas and recover heat.

[0013] Preferably, the pulverized coal cyclone burner is located at the center of the axis of the high-temperature cyclone combustion pre-combustion chamber, and its cyclone intensity is adjustable.

[0014] Preferably, a flow guiding structure is provided at the connection between the high-temperature cyclone combustion pre-combustion chamber and the lower slag discharge chamber to guide the liquid slag film to flow smoothly into the lower slag discharge chamber.

[0015] Another aspect of the present invention provides a high-temperature liquid ash discharge combustion method for strongly slagging, high-alkali coal, comprising the following steps:

[0016] Step 1: Pulverized coal made from highly slagging and alkaline coal is fed into an insulated high-temperature cyclone combustion pre-combustion chamber through a pulverized coal cyclone burner.

[0017] Step 2: High-speed secondary air is introduced into the high-temperature cyclone combustion pre-combustion chamber through the high-speed secondary air inlet, so that the pulverized coal and the secondary air form a strong swirling flow field in the pre-combustion chamber and high-temperature combustion occurs;

[0018] Step 3: During the high-temperature combustion process, the low-melting components in the coal melt preferentially and are thrown to the inner wall of the pre-combustion chamber under the centrifugal force of the strong swirling flue gas to form a liquid slag film. The liquid slag film captures the coal coke, semi-coke and fly ash particles in the flue gas. The particles undergo secondary combustion on the slag film, and their ash melts in the slag film and flows into the insulated lower slag discharge chamber with the slag film.

[0019] Step 4: The ash-containing flue gas at the outlet of the pre-combustion chamber flows from bottom to top through the ash-collecting screen. The sticky ash in the flue gas is captured by the ash-collecting screen and falls into the lower ash discharge chamber. The liquid ash is discharged from the liquid ash discharge port at the bottom of the lower ash discharge chamber.

[0020] Step 5: The high-temperature flue gas and a small amount of fly ash purified by the slag removal screen enter the water-cooled wall-type upper slag discharge chamber. After being appropriately cooled, it is sent from the outlet of the upper slag discharge chamber into the boiler furnace for radiative heat exchange.

[0021] Preferably, in step 2, the wind speed of the high-speed secondary air is matched with the coal powder conveying speed, so that the centrifugal force of the swirling field is sufficient to throw the liquid molten slag onto the inner wall of the pre-combustion chamber.

[0022] Preferably, in step 2, the combustion temperature is maintained by the insulation structure of the high-temperature cyclone combustion pre-combustion chamber to ensure that the low-melting components in the coal are fully melted.

[0023] Preferably, in step 3, the thickness of the liquid slag film is maintained within a preset range by adjusting the coal powder supply, secondary air velocity, and slag discharge rate to ensure the fluidity and capture efficiency of the slag film.

[0024] Preferably, in step 4, the staggered arrangement of the fins of the ash trap extends the flue gas flow path and increases the probability of capturing sticky ash.

[0025] Preferably, in step 5, the water-cooled wall of the upper slag discharge chamber carries away some of the heat from the flue gas through a cooling medium, thereby reducing the flue gas temperature to within the range suitable for the boiler furnace.

[0026] Preferably, during combustion, the proportion of molten coal ash discharged is not less than 85%, and the proportion of fly ash entering the boiler furnace is not more than 15%.

[0027] The technical solution of the present invention has the following technical effects:

[0028] (1) This invention constructs a stable high-temperature combustion environment (1500-1700℃) through an adiabatic high-temperature cyclone combustion pre-combustion chamber. Combined with a strong swirling flow field design, it enables the low-melting components in the coal to fully melt, forming a liquid slag film to capture coal coke, semi-coke and fly ash particles. After secondary slag collection by the slag collection screen, it finally achieves 85-90% coal ash melting and discharge, with only 10-15% of non-melting fly ash entering the boiler furnace. This completely solves the problem that conventional combustion methods cannot fully burn strongly slagging high-alkali coal, and greatly improves the utilization rate of high-alkali coal resources.

[0029] (2) The present invention significantly reduces the risk of fouling at the tail of the boiler. Since most of the molten slag and semi-molten slag are separated and discharged in the pre-combustion chamber and the slag discharge chamber, the amount of fly ash entering the furnace is greatly reduced. Moreover, the remaining fly ash is mostly non-melting particles with low viscosity, which are not easy to foul and slag on the tail heating surface. This significantly reduces the risk of fouling at the tail heating surface of the boiler, reduces the number of shutdowns for maintenance, and lowers the operation and maintenance costs.

[0030] (3) The strong swirling flow field design of the present invention enables the pulverized coal and secondary air to mix fully and the combustion to be more complete. At the same time, the secondary combustion of coal coke and semi-coke particles on the slag film further improves the fuel utilization rate. The boiler thermal efficiency is 3-5% higher than that of conventional solid slag discharge boilers. The insulation structure of the pre-combustion chamber and the lower slag discharge chamber reduces heat loss. The water-cooled wall of the upper slag discharge chamber recovers some of the flue gas heat, which improves energy utilization efficiency and reduces energy consumption.

[0031] (4) The present invention has strong operational stability and high safety. The continuous formation and flow of liquid slag film avoids the accumulation and blockage of molten slag in the pre-combustion chamber. The controllable slag discharge valve can flexibly adjust the slag discharge rate to ensure the stability of the slag discharge process. The slag collection screen adopts a staggered fin structure, which not only ensures the slag collection efficiency, but also reduces the flow resistance of flue gas and avoids the problem of poor flue gas flow. All components are made of high temperature resistant, wear-resistant and corrosion-resistant materials, which extends the service life of the equipment and improves the operational safety.

[0032] (5) By adjusting parameters such as the swirl intensity of pulverized coal and the secondary air velocity, this invention can be adapted to strongly slagging, high-alkali coals with different coal quality characteristics. Furthermore, different specifications of burners can be designed according to boiler capacity requirements, making it suitable for various coal-fired equipment such as power plant boilers and industrial boilers, and possessing broad industrial application prospects. The following will further explain the concept, specific structure, and technical effects of this invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of this invention. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a high-temperature liquid slag discharge burner suitable for strongly slagging, high-alkali coal, according to a preferred embodiment of the present invention.

[0034] In the diagram: 1. Pulverized coal cyclone burner; 2. High-speed secondary air inlet; 3. High-temperature cyclone combustion pre-combustion chamber; 4. Lower slag discharge chamber; 5. Liquid slag discharge port; 6. Slag collection screen; 7. Upper slag discharge chamber; 8. High-temperature hot flue gas inlet; 9. Boiler furnace. Detailed Implementation

[0035] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0036] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0037] like Figure 1 As shown, this invention provides a high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal, comprising a high-temperature cyclone combustion pre-combustion chamber 3, a lower ash discharge chamber 4, a ash trapping screen 6, and an upper ash discharge chamber 7; the high-temperature cyclone combustion pre-combustion chamber 3 is an insulated structure, equipped with a pulverized coal cyclone burner 1 and a high-speed secondary air inlet 2; the lower ash discharge chamber 4 is an insulated structure, its top connected to the outlet of the high-temperature cyclone combustion pre-combustion chamber 3, and its bottom provided with a liquid ash discharge port 5; the ash trapping screen 6 is disposed between the lower ash discharge chamber 4 and the upper ash discharge chamber 7, for capturing sticky ash in the flue gas; the upper ash discharge chamber 7 is a water-cooled wall structure, equipped with a high-temperature hot flue gas inlet 8, and its outlet connected to the boiler furnace 9.

[0038] The inner wall of the high-temperature cyclone combustion pre-combustion chamber 3 is equipped with a high-temperature resistant insulation layer. This high-temperature resistant insulation layer is made of ceramic fiber composite material, which has the characteristics of high temperature resistance, low thermal conductivity, and good heat insulation effect. It can effectively reduce heat loss in the pre-combustion chamber and ensure that the combustion temperature is maintained within the high temperature range required for coal ash melting. The shell of the high-temperature cyclone combustion pre-combustion chamber 3 is welded from heat-resistant steel plates. A heat insulation lining is provided between the shell and the insulation layer to further improve the heat insulation performance and protect the shell from high-temperature corrosion.

[0039] The high-speed secondary air inlets 2 are evenly arranged around the circumference of the high-temperature cyclone combustion pre-combustion chamber 3, with a quantity of 4-8. The inlet axis forms an angle of 30-60 degrees with the central axis of the high-temperature cyclone combustion pre-combustion chamber 3. This angle design enables the secondary air to form a strong rotating airflow after entering the pre-combustion chamber, which is fully mixed with the pulverized coal sprayed out by the pulverized coal cyclone burner 1 to form a stable strong cyclone combustion field. This ensures that the pulverized coal is fully burned and generates sufficient centrifugal force to throw the liquid slag onto the inner wall of the pre-combustion chamber.

[0040] The pulverized coal swirl burner 1 is located at the center of the axis of the high-temperature cyclone combustion pre-combustion chamber 3. It includes a pulverized coal nozzle and swirl blades. The angle of the swirl blades can be adjusted by an adjustment mechanism to change the swirl intensity of the pulverized coal and adapt to different coal properties and combustion conditions. The inlet of the pulverized coal swirl burner 1 is connected to the pulverized coal conveying pipeline, and the pulverized coal powder made from highly slagging, high-alkali coal is stably conveyed to the pre-combustion chamber by a pulverized coal conveying fan.

[0041] The ash trap 6 is a finned structure made of high-temperature resistant alloy material, with an anti-oxidation and anti-corrosion coating to extend its service life. The fins are staggered along the flue gas flow direction, with a spacing of 30-80mm. This design extends the flow path of flue gas within the ash trap 6 area, increasing the probability of contact between sticky ash and the fins while reducing flue gas flow resistance. The two ends of the ash trap 6 are connected to the top flange of the lower ash discharge chamber 4 and the bottom flange of the upper ash discharge chamber 7, respectively, facilitating installation, disassembly, maintenance, and cleaning.

[0042] The lower slag discharge chamber 4 has a cylindrical structure with an anti-wear lining on its inner wall. The anti-wear lining is made of high-alumina refractory material, which can withstand the scouring and erosion of liquid slag. The bottom of the lower slag discharge chamber 4 has a conical structure, and the liquid slag discharge port 5 is located at the center of the bottom of the cone. It is equipped with a controllable slag discharge valve, which adopts a high-temperature resistant ceramic sealing structure and can automatically adjust the valve opening according to the slag level, control the discharge rate of liquid slag, and avoid slag overflow or poor slag discharge.

[0043] The upper ash discharge chamber 7 has a square or cylindrical structure, and its water-cooled wall adopts a membrane wall structure, which is welded from seamless steel pipes and fins. Demineralized water or steam, or other cooling media, circulates within the water-cooled wall. The cooling media is connected to the boiler water circulation system through inlet and outlet headers. The water-cooled wall of the upper ash discharge chamber 7 not only moderately cools the high-temperature flue gas, reducing its temperature from 1500-1700℃ to 1200-1400℃ to prevent damage to the refractory material of the boiler furnace 9 due to excessively high temperatures, but also recovers some of the heat from the flue gas, improving energy efficiency. The upper ash discharge chamber 7 has a high-temperature hot flue gas inlet 8 at the top and an outlet on the side that communicates with the boiler furnace 9. A guide plate is installed at the outlet to guide the flue gas evenly into the furnace for radiant heat exchange.

[0044] A flow guiding structure is provided at the connection between the high-temperature cyclone combustion pre-combustion chamber 3 and the lower slag discharge chamber 4. The flow guiding structure is an annular flow guide plate, the inclination angle of which is adapted to the inner wall of the lower slag discharge chamber 4. This can guide the liquid slag film on the inner wall of the pre-combustion chamber to flow smoothly into the lower slag discharge chamber 4, avoiding the accumulation or detachment of the slag film at the connection and ensuring the continuity of the slag discharge process.

[0045] This invention also provides a high-temperature liquid ash discharge combustion method for strongly slagging, high-alkali coal, comprising the following steps:

[0046] Step 1: The highly alkali coal with strong slagging is crushed and ground into pulverized coal with a particle size of 80-200 mesh. The pulverized coal is then fed into the insulated high-temperature cyclone combustion pre-combustion chamber 3 through the pulverized coal conveying pipeline and the pulverized coal cyclone burner 1. The conveying speed of the pulverized coal is adjusted by the pulverized coal conveying fan to ensure the uniform distribution of pulverized coal in the pre-combustion chamber.

[0047] Step 2: High-speed secondary air is introduced into the high-temperature cyclone combustion pre-combustion chamber 3 through the high-speed secondary air inlet 2. The secondary air is preheated to 300-500℃ by the air preheater, and the wind speed is controlled at 30-50m / s. The secondary air and the pulverized coal sprayed from the pulverized coal cyclone burner 1 form a strong swirling field in the pre-combustion chamber. At the same time, the pulverized coal is ignited by the ignition device, resulting in high-temperature combustion. The combustion temperature is maintained at 1500-1700℃ by the insulation structure of the high-temperature cyclone combustion pre-combustion chamber 3 to ensure that the low melting components in the coal are fully melted.

[0048] Step 3: During high-temperature combustion, alkali metal compounds such as sodium and potassium, as well as low-melting-point components such as iron oxides in the coal, preferentially melt to form liquid slag. Under the centrifugal force of the strongly swirling flue gas, the liquid slag is thrown onto the inner wall of the pre-combustion chamber, forming a continuous liquid slag film with a thickness of 5-15 mm. The liquid slag film has high viscosity and temperature, which can efficiently capture the flowing coal coke, semi-coke, and fly ash particles. These particles stay on the surface of the slag film and undergo secondary combustion, further releasing heat. At the same time, the ash in the particles melts in the high-temperature slag film and integrates into the slag film. By adjusting the coal powder supply, secondary air velocity, and slag discharge rate, the thickness of the liquid slag film is maintained within a preset range to ensure the fluidity and capture efficiency of the slag film.

[0049] Step 4: The ash-containing flue gas (temperature approximately 1500-1600℃) from the pre-combustion chamber outlet flows upward through the slag collection screen 6. After the molten slag, semi-molten slag, and other sticky ash in the flue gas come into contact with the fin surface of the slag collection screen 6, they condense and adhere to the fins due to the decrease in temperature and the stickiness. As the amount of ash adhering increases, the ash falls off under the action of gravity and falls into the lower slag discharge chamber 4. The liquid slag in the lower slag discharge chamber 4 collects and is discharged from the liquid slag discharge port 5 at the bottom, entering the slag pool for cooling treatment.

[0050] Step 5: The high-temperature flue gas and a small amount of non-melting fly ash (temperature about 1400-1500℃) purified by the slag screen 6 enter the water-cooled wall upper slag discharge chamber 7. The cooling medium in the water-cooled wall exchanges heat with the flue gas, reducing the flue gas temperature to 1200-1400℃. The cooled high-temperature flue gas is sent from the outlet of the upper slag discharge chamber 7 into the boiler furnace 9, where it undergoes radiative heat exchange with the heating surface. After releasing heat, it enters the tail flue for subsequent convective heat exchange.

[0051] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, so as to fully understand the purpose, features and effects of the present invention.

[0052] Example 1: High-temperature liquid ash discharge burner for a 300MW power plant boiler

[0053] The high-temperature liquid slag discharge burner in this embodiment is used in a 300MW power plant boiler and is suitable for strongly slagging, high-alkali coal (alkali metal content) from a mining area in Xinjiang. , The specific structure is as follows:

[0054] High-temperature cyclone combustion pre-combustion chamber 3: It adopts a cylindrical structure with an inner diameter of 1.5m and a length of 4m. The shell is welded from Q345R heat-resistant steel plate with a wall thickness of 20mm. The inner wall is equipped with a 250mm thick high-temperature insulation layer made of alumina ceramic fiber composite material. This material has a thermal conductivity ≤0.15W / (m·K) (at 1000℃) and a long-term operating temperature of up to 1800℃. A 50mm thick heat-insulating lining made of aluminum silicate fiberboard is installed between the shell and the insulation layer to further improve the insulation effect. An inspection door is located at one end of the pre-combustion chamber for easy internal maintenance and cleaning.

[0055] Pulverized coal cyclone burner 1: Located at the center of the pre-combustion chamber, it adopts a dual-air-adjustable structure, including a primary air pulverized coal channel and a secondary air cyclone channel; the inner diameter of the primary air pulverized coal channel is 200mm, and the pulverized coal conveying speed is 15-20m / s; the secondary air cyclone channel is equipped with adjustable cyclone blades, and the blade angle adjustment range is 15-45 degrees, which is remotely controlled by an electric actuator; the burner outlet has a flared structure to expand the diffusion range of pulverized coal and improve the mixing effect with the secondary air.

[0056] High-speed secondary air inlet 2: Eight inlets are evenly arranged around the pre-combustion chamber, with an inlet diameter of 150mm and an inlet axis at a 45-degree angle to the central axis of the pre-combustion chamber. The secondary air duct is made of heat-resistant steel pipe, and a flange sealing structure is provided at the connection with the pre-combustion chamber to prevent air leakage. The secondary air is preheated to 400-450℃ by an air preheater, and the wind speed is controlled at 40-45m / s. The air volume of the secondary air is controlled by adjusting the valve to ensure that the excess air coefficient in the pre-combustion chamber is 1.1-1.2.

[0057] Lower slag discharge chamber 4: A cylindrical structure with an inner diameter of 2.0m and a height of 3m. The shell is welded from Q345R steel plate with a wall thickness of 16mm; the inner wall is lined with a 200mm thick wear-resistant layer and uses high-alumina refractory bricks. The refractory bricks are constructed with a refractory content ≥85%, and high-temperature refractory mortar is used to seal between them. The top of the lower slag discharge chamber 4 is connected to the outlet of the pre-combustion chamber via a flange. An annular guide plate is installed at the connection, with an inclination angle of 60 degrees, to guide the liquid slag film to flow smoothly into the slag discharge chamber. The bottom has a conical structure with a cone angle of 30 degrees. The liquid slag discharge port 5 is located at the center of the bottom of the cone, with a diameter of 300mm. It is equipped with an electric ceramic gate valve, and the sealing surface of the valve is made of silicon nitride ceramic material, which is resistant to high temperature and wear. A slag level sensor is installed at the slag discharge port to monitor the slag level in the slag discharge chamber in real time. When the slag level reaches the set upper limit, the valve automatically opens to increase the slag discharge rate. When the slag level is lower than the set lower limit, the valve automatically closes to prevent air leakage.

[0058] Slag trap 6: Located between the lower slag discharge chamber 4 and the upper slag discharge chamber 7, it adopts a finned structure with a total width of 2.0m and a height of 1.5m. The fins are made of 310S high-temperature resistant stainless steel with a thickness of 8mm, a height of 120mm, and a spacing of 60mm, arranged in a staggered pattern. The surface of the fins is coated with a zirconium oxide coating with a coating thickness of 0.5mm, and the oxidation resistance temperature can reach 1700℃. The frame of the slag trap 6 is welded from carbon steel and is bolted to the flanges of the lower slag discharge chamber 4 and the upper slag discharge chamber 7 for easy disassembly and replacement.

[0059] Upper ash discharge chamber 7: A square structure with sides of 2.5m and a height of 3m. The water-cooled wall adopts a membrane wall structure, with steel pipes of φ60×5mm, made of 20G boiler steel. The fins are 6mm thick, made of the same material as the steel pipes. The steel pipes and fins are welded together by submerged arc welding, resulting in a tight weld without air leakage. The inlet and outlet headers of the water-cooled wall adopt a cylindrical structure with a diameter of 300mm, made of 12Cr1MoV. The cooling medium is demineralized water, with a flow rate controlled at 80-100m³ / h, and is forcibly circulated by a water pump. The top of the upper ash discharge chamber 7 is equipped with a high-temperature hot flue gas inlet 8, the size of which matches the outlet of the ash trap 6. The side has an outlet connected to the boiler furnace 9, with an outlet size of 2.0m×2.0m, equipped with a guide plate. The angle of the guide plate is adjustable to guide the flue gas evenly into the furnace. The shell of the upper ash discharge chamber 7 adopts a carbon steel frame structure with an external insulation layer to reduce heat loss.

[0060] The combustion method in this embodiment is as follows:

[0061] Step 1: Crush and grind the highly alkali coal with strong slagging into 100-150 mesh coal powder, and send it into the coal powder cyclone burner 1 through the coal powder silo, coal feeder and coal powder conveying pipeline. The coal powder conveying speed is controlled at 18m / s, and the supply is adjusted according to the load demand of the boiler, ranging from 50-80t / h.

[0062] Step 2: Secondary air is preheated to 420℃ by an air preheater and then introduced into the pre-combustion chamber through high-speed secondary air inlet 2 at a velocity of 42m / s. The air volume is matched with the coal powder supply to ensure an excess air coefficient of 1.15. The coal powder is ignited by an ignition device (plasma igniter). The coal powder and secondary air form a strong swirling flow field in the pre-combustion chamber, resulting in high-temperature combustion. Due to the insulating structure of the pre-combustion chamber, the combustion temperature is maintained at 1550-1650℃, and the low-melting components in the coal (such as...) are... (etc.) are fully melted.

[0063] Step 3: Under the centrifugal force of the strong swirling flue gas (centrifugal force approximately 1200N), the molten slag is thrown onto the inner wall of the pre-combustion chamber, forming a continuous liquid slag film with a thickness of 8-12mm. The temperature of the slag film is approximately 1500-1550℃, and it has high viscosity. Coal, coke, semi-coke, and fly ash particles (particle size ≤100μm) flowing through the slag film are captured by the slag film. The particles stay on the surface of the slag film for 3-5 seconds, undergoing secondary combustion, with a combustion efficiency of over 99%. The ash in the particles melts in the slag film and integrates into it, causing the slag film thickness to gradually increase. By adjusting the opening of the slag discharge valve, the thickness of the slag film is maintained at approximately 10mm to ensure the fluidity of the slag film.

[0064] Step 4: The temperature of the ash-containing flue gas at the outlet of the pre-combustion chamber is about 1550℃, and the flow velocity is 8-10m / s. It flows from bottom to top through the ash collection screen 6. After the molten slag, semi-molten slag and other sticky ash slag (particle size ≤50μm) in the flue gas come into contact with the fin surface of the ash collection screen 6, they quickly solidify and adhere. After the amount of adhesion reaches a certain level (about 10-15 minutes), they fall off under the action of gravity and fall into the lower ash discharge chamber 4. The ash collection efficiency of the ash collection screen 6 can reach more than 80%, and the content of sticky ash slag in the flue gas after ash collection is greatly reduced.

[0065] Step 5: The flue gas temperature after purification by the slag trap 6 is about 1450℃. It enters the upper slag discharge chamber 7 and exchanges heat with the demineralized water in the water-cooled wall. The flue gas temperature drops to 1250-1300℃. The cooled flue gas carries a small amount of non-melting fly ash (particle size ≤20μm) and is sent from the outlet of the upper slag discharge chamber 7 into the boiler furnace 9. In the furnace, it exchanges heat with the water-cooled wall through radiation. After releasing heat, it enters the tail flue and undergoes convective heat exchange through the superheater, reheater, economizer, air preheater and other heating surfaces. Finally, it is discharged from the chimney.

[0066] The operational results of this embodiment are as follows: During combustion, the highly slagging, high-alkali coal is fully burned, eliminating the need for blending with low-alkali coal; the discharge rate of molten coal ash reaches 88%, and the proportion of fly ash entering the furnace is only 12%; the fouling degree of the boiler's tail heating surface is reduced by more than 90% compared to conventional solid slag discharge boilers, and the shutdown maintenance cycle is extended from 3 months to 12 months; the boiler thermal efficiency reaches 92.5%, which is 4.2% higher than that of conventional boilers, saving approximately 5,000 tons of standard coal annually, demonstrating significant economic and environmental benefits.

[0067] Example 2: High-temperature liquid ash discharge burner for a 75t / h industrial boiler

[0068] The high-temperature liquid slag discharge burner in this embodiment is used in a 75t / h industrial boiler and is suitable for strongly slagging, high-alkali coal (alkali metal content) from another mining area in Xinjiang. , The specific structure is as follows:

[0069] High-temperature cyclone combustion pre-combustion chamber 3: inner diameter 1.0m, length 2.5m, shell is welded from Q245R steel plate with a wall thickness of 16mm; the inner wall is provided with a 200mm thick high-temperature resistant heat insulation layer, which is made of zirconia ceramic fiber composite material with a thermal conductivity ≤0.12W / (m·K) (at 1000℃); a 30mm thick heat insulation lining is provided between the shell and the heat insulation layer, which is made of aluminum silicate fiber felt.

[0070] Coal swirl burner 1: It adopts a single-air adjustable structure, with an inner diameter of 150mm for the primary air and coal powder channel, and a coal powder conveying speed of 12-18m / s; the swirl blade angle adjustment range is 20-40 degrees, which can be adjusted by a manual actuator.

[0071] High-speed secondary air inlet 2: Six inlets are evenly arranged around the circumference of the pre-combustion chamber. The inlet pipe diameter is 100mm, and the inlet axis is at a 40-degree angle to the central axis of the pre-combustion chamber. The secondary air is preheated to 350-400℃, the wind speed is controlled at 35-40m / s, and the excess air coefficient is 1.1-1.15.

[0072] Lower slag discharge chamber 4: inner diameter 1.5m, height 2.5m, shell wall thickness 14mm; the inner wall is equipped with a 150mm thick wear-resistant lining, using clay refractory bricks ( Content ≥60%); the top is connected to the pre-combustion chamber outlet by a flange, the guide plate is inclined at an angle of 55 degrees; the bottom cone angle is 35 degrees, the liquid slag discharge port 5 has a diameter of 250mm, equipped with a manual ceramic gate valve, and the slag discharge rate is manually adjusted in conjunction with the slag level gauge.

[0073] Slag trap 6: Total width 1.5m, height 1.2m; fins are made of 2520 high temperature resistant stainless steel, 6mm thick, 100mm high, 50mm spacing, staggered arrangement; surface is sprayed with aluminum oxide coating, 0.3mm thick.

[0074] Upper slag discharge chamber 7: It is a cylindrical structure with a diameter of 1.8m and a height of 2.5m; the water-cooled wall steel pipe has a specification of φ51×4mm and a material of 20G; the cooling medium is demineralized water, and the flow rate is controlled at 40-60m³ / h; the outlet is connected to the boiler furnace 9 and is equipped with a fixed guide plate.

[0075] The combustion method in this embodiment is basically the same as that in Embodiment 1. The key parameters after adjustment are as follows: the coal powder particle size is 80-120 mesh, the conveying speed is 15m / s, and the supply is 8-12t / h; the secondary air temperature is 380℃ and the wind speed is 38m / s; the pre-combustion chamber combustion temperature is 1500-1600℃; the liquid slag film thickness is 6-10mm; the slag collection efficiency of the slag collection screen 6 is about 78%; the proportion of molten coal ash discharged reaches 85%, and the proportion of fly ash entering the furnace is 15%.

[0076] Operational results: Strong slagging and high-alkali coal can be fully burned, significantly reducing the risk of fouling on the boiler's tail heating surface, and extending the shutdown and maintenance cycle from 2 months to 8 months; the boiler's thermal efficiency reaches 91.8%, which is 3.5% higher than that of conventional industrial boilers, saving about 800 tons of standard coal per year, meeting the energy conservation and consumption reduction requirements of industrial production.

[0077] Example 3: High-temperature liquid ash discharge burner with optimized combustion stability design

[0078] Based on Example 1, this embodiment optimizes the burner structure to further improve operational stability. The specific optimizations are as follows:

[0079] A temperature sensor is installed on the inner wall of the high-temperature cyclone combustion pre-combustion chamber 3 to monitor the combustion temperature in the pre-combustion chamber in real time. The temperature signal is fed back to the control system. By adjusting the preheating temperature and air volume of the secondary air, the combustion temperature is stabilized at 1550-1600℃ to avoid excessive temperature fluctuations that could lead to unstable slag film.

[0080] A pulverized coal concentration sensor is installed at the outlet of the pulverized coal swirl burner 1 to monitor the uniformity of pulverized coal diffusion. When the concentration distribution is uneven, the distribution of pulverized coal is optimized by adjusting the swirl blade angle and the primary air velocity to ensure uniform combustion.

[0081] A vibration device is installed on the fins of the ash collection screen 6. It is activated every 30 minutes with a vibration frequency of 50Hz and an amplitude of 2-3mm. This promotes the shedding of ash and slag attached to the fins, prevents ash and slag from accumulating and clogging the flue gas passage, and improves the long-term operational stability of the ash collection screen 6.

[0082] A pressure sensor is installed on the side wall of the lower slag discharge chamber 4 to monitor pressure changes in the slag discharge chamber. When the pressure rises abnormally (which may be due to blockage of the slag discharge port), an alarm signal is issued in a timely manner, and the unblocking device of the slag discharge port is automatically activated to ensure smooth slag discharge.

[0083] The operational results of this embodiment are as follows: the fluctuation range of combustion temperature is controlled within ±30℃, the stability of the liquid slag film is significantly improved, and there is no phenomenon of slag film falling off or accumulating; the flue gas flow resistance of the slag collection screen 6 remains stable and no blockage occurs; the slag discharge process is continuous and smooth, and no blockage occurs; the operational stability of the entire combustion system is greatly improved, and the average fault-free operation time reaches more than 8,000 hours.

[0084] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal, characterized in that, The system includes a high-temperature cyclone combustion pre-combustion chamber, a lower ash discharge chamber, a ash trap, and an upper ash discharge chamber. The high-temperature cyclone combustion pre-combustion chamber is an insulated structure, equipped with a pulverized coal cyclone burner and a high-speed secondary air inlet. The lower ash discharge chamber is also an insulated structure, with its top connected to the outlet of the high-temperature cyclone combustion pre-combustion chamber and its bottom having a liquid ash discharge port. The ash trap is located between the lower and upper ash discharge chambers and is used to capture sticky ash and slag in the flue gas. The upper ash discharge chamber has a water-cooled wall structure, with a high-temperature hot flue gas inlet and its outlet connected to the boiler furnace.

2. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, The inner wall of the high-temperature cyclone combustion pre-combustion chamber is provided with a high-temperature resistant insulation layer, which is made of ceramic fiber composite material.

3. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, The high-speed secondary air inlet is uniformly arranged along the circumference of the high-temperature cyclone combustion pre-combustion chamber, and the inlet axis is at a preset angle to the central axis of the high-temperature cyclone combustion pre-combustion chamber to form a strong swirling flow field.

4. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, The slag trap has a finned structure with the fins arranged in a staggered pattern along the flue gas flow direction and the surface of the fins is coated with a high-temperature resistant coating.

5. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, The inner wall of the lower slag discharge chamber is provided with a wear-resistant lining, and the liquid slag discharge port is equipped with a controllable slag discharge valve to adjust the discharge rate of the liquid slag.

6. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, The water-cooled wall of the upper slag discharge chamber adopts a membrane wall structure, and a cooling medium flows inside the water-cooled wall to moderately cool the high-temperature flue gas and recover heat.

7. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, The pulverized coal swirl burner is located at the center of the axis of the high-temperature cyclone combustion pre-combustion chamber, and its swirl intensity is adjustable.

8. The high-temperature liquid ash discharge burner suitable for strongly slagging, high-alkali coal as described in claim 1, characterized in that, A flow guiding structure is provided at the connection between the high-temperature cyclone combustion pre-combustion chamber and the lower slag discharge chamber to guide the liquid slag film to flow smoothly into the lower slag discharge chamber.

9. A method for high-temperature liquid slag discharge combustion of strongly slagging, high-alkali coal, characterized in that, Includes the following steps: Step 1: Pulverized coal made from highly slagging and alkaline coal is fed into an insulated high-temperature cyclone combustion pre-combustion chamber through a pulverized coal cyclone burner. Step 2: High-speed secondary air is introduced into the high-temperature cyclone combustion pre-combustion chamber through the high-speed secondary air inlet, so that the pulverized coal and the secondary air form a strong swirling flow field in the pre-combustion chamber and high-temperature combustion occurs; Step 3: During the high-temperature combustion process, the low-melting components in the coal melt preferentially and are thrown to the inner wall of the pre-combustion chamber under the centrifugal force of the strong swirling flue gas to form a liquid slag film. The liquid slag film captures the coal coke, semi-coke and fly ash particles in the flue gas. The particles undergo secondary combustion on the slag film, and their ash melts in the slag film and flows into the insulated lower slag discharge chamber with the slag film. Step 4: The ash-containing flue gas at the outlet of the pre-combustion chamber flows from bottom to top through the ash-collecting screen. The sticky ash in the flue gas is captured by the ash-collecting screen and falls into the lower ash discharge chamber. The liquid ash is discharged from the liquid ash discharge port at the bottom of the lower ash discharge chamber. Step 5: The high-temperature flue gas and a small amount of fly ash purified by the slag removal screen enter the water-cooled wall-type upper slag discharge chamber. After being appropriately cooled, it is sent from the outlet of the upper slag discharge chamber into the boiler furnace for radiative heat exchange.

10. The high-temperature liquid slag discharge combustion method for strongly slagging, high-alkali coal as described in claim 9, characterized in that, In step 2, the wind speed of the high-speed secondary air is matched with the coal powder conveying speed, so that the centrifugal force of the swirling field is sufficient to throw the liquid molten slag onto the inner wall of the pre-combustion chamber.

11. The high-temperature liquid slag discharge combustion method for strongly slagging, high-alkali coal as described in claim 9, characterized in that, In step 2, the combustion temperature is maintained by the insulation structure of the high-temperature cyclone combustion pre-combustion chamber to ensure that the low-melting components in the coal are fully melted.

12. The high-temperature liquid slag discharge combustion method for strongly slagging, high-alkali coal as described in claim 9, characterized in that, In step 3, the thickness of the liquid slag film is maintained within a preset range by adjusting the coal powder supply, secondary air velocity, and slag discharge rate to ensure the fluidity and capture efficiency of the slag film.

13. The high-temperature liquid slag discharge combustion method for strongly slagging, high-alkali coal as described in claim 9, characterized in that, In step 4, the staggered arrangement of the fins of the ash trap extends the flue gas flow path and increases the probability of capturing sticky ash.

14. The high-temperature liquid slag discharge combustion method for strongly slagging, high-alkali coal as described in claim 9, characterized in that, In step 5, the water-cooled wall of the upper slag discharge chamber removes some of the heat from the flue gas through the cooling medium, thereby reducing the flue gas temperature to within the range suitable for the boiler furnace.

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