A multi-stage air supply device for a marine gas combustion unit

Abstract

The application provides a multi-stage air supply device for a ship gas combustion unit, comprising one or more air fans, a mixing box connected by flexible connecting pieces and a non-return air door, a grid plate arranged above an air outlet of the mixing box, a combustion chamber cylinder above the grid plate, air provided by the air fan mixed in the mixing box, discharged to a first air supply port at the bottom of the combustion chamber cylinder through the outlet grid plate, the first air supply port at the bottom of the combustion chamber cylinder, an outer ring plate, an intermediate ring plate, an inner ring plate and a burner arranged in sequence from outside to inside, the side wall of the combustion chamber cylinder above the burner, a second air supply port, a third air supply port and a fourth air supply port arranged in sequence from top to bottom. The application has high integration, small size, light weight and a key part of the combustion chamber which is convenient to replace.

Description

Technical Field

[0001] This invention relates to a multi-stage air supply device for a ship's gas combustion unit, used for supplying air for the combustion of fuel gas and the cooling of combustion products in the gas combustion unit, belonging to the field of air supply technology. Background Technology

[0002] Gas combustion units, as combustible gas processing devices, have been widely installed on LNG carriers in recent years. During operation, they burn combustible gases and cool the combustion products before emission. The mainstream cooling method is to mix air into the high-temperature combustion products for mass and heat transfer cooling. A small number of water-spray cooling designs exist, but due to their complex control and unstable combustion, they are less widely accepted in the market. The challenges of air cooling lie in two aspects: material protection for the high-temperature radiation zone at the root of the combustion chamber, and the air distribution structure to adapt to varying gas flow rates. For the former, solutions include applying castable refractory insulation to the inner surface of the combustion chamber root and using a porous mesh structure to draw in low-temperature air for cooling. The first method offers higher safety but significantly increases weight; the second method is lightweight but has low strength, and under high loads, it may deform, tear, or even melt. For the latter, solutions include separate and centralized supply of combustion and cooling air. The first method provides stable combustion but has a larger structural size; the second method has a smaller structural size and more stable combustion.

[0003] Therefore, it is necessary to design an air supply device that provides centralized air supply and protects the material of the high-temperature radiation zone at the root of the combustion chamber, so as to provide effective cooling for the combustion chamber of the gas combustion unit while ensuring stable combustion of the gas. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a multi-stage air supply device for a gas combustion unit, which provides effective cooling for the combustion chamber of the gas combustion unit, ensures that the high temperature radiation absorbed by the combustion chamber during operation does not exceed the allowable temperature of the material, ensures effective ignition at the root of the burner, and makes the combustion chamber structure compact and lightweight, so as to overcome the shortcomings of the prior art.

[0005] The technical solution adopted in this invention is as follows:

[0006] A multi-stage air supply device for a marine gas combustion unit includes one or more fans. The fans are connected to a mixing box via flexible connectors and backflow preventers. A grid plate is provided above the air outlet of the mixing box. The combustion chamber is located above the grid plate. The air supplied by the fans is mixed in the mixing box and discharged to the first-stage air supply port at the bottom of the combustion chamber after passing through the outlet grid plate.

[0007] The bottom air supply port of the combustion chamber shell is provided with an outer ring plate, a middle ring plate, an inner ring plate, and a burner in sequence from the outside to the inside;

[0008] Located above the burner, the side wall of the combustion chamber cylinder is provided with a secondary air supply port, a tertiary air supply port, and a quaternary air supply port from bottom to top;

[0009] The primary air supply is distributed through the inner ring plate at the bottom of the combustion chamber. Part of the air is injected through the inner ring plate to the root of the burner gas injection. The air and gas are mixed and used for effective ignition by the ignition device fixed on the inner ring plate, and regional backflow is formed to prevent flameout.

[0010] The primary air supply is distributed through the intermediate and outer ring plates of the combustion chamber. The air is injected through the intermediate ring plate and the gap between the intermediate and outer ring plates to the periphery of the root flame, directly mixing with the high-temperature flue gas generated by combustion to cool it down and compress the flame size, increasing the distance between the outer flame and the inner wall of the combustion chamber. The remaining air sweeps along the outside of the combustion chamber, forming the secondary, tertiary, and quaternary air supply to protect the combustion chamber.

[0011] An exhaust tower is installed outside the combustion chamber cylinder.

[0012] The height of the secondary air supply port is 0.2 of the total height of the combustion chamber cylinder, and the secondary air supply accounts for 50% of the total air volume. It uses a large air volume to compress the size of the bottom flame and reduce the temperature of the combustion chamber cylinder wall to less than 500℃, thereby achieving the purpose of controlling the size of the device and protecting the combustion chamber cylinder.

[0013] The height of the third-stage air supply vent is 0.4 of the total height of the combustion chamber cylinder and accounts for 12.5% ​​of the total air volume, compressing the flame expansion part in the middle section.

[0014] The opening height of the fourth-stage air supply inlet is 0.65 of the total height of the combustion chamber cylinder and accounts for 12.5% ​​of the total air volume, which compresses the high-level expansion part of the flame.

[0015] A reinforcing ring plate is installed at the secondary air supply port of the combustion chamber cylinder.

[0016] The multi-stage air supply structure uses a centralized air supply method with a mixing box to input the total air volume. This, combined with the outer, middle, and inner ring plates of the combustion chamber, adaptively distributes the air volume. Appropriate air volume is allocated at the front to cool the mechanical structure at the burner root and mix with the combustion gas at the root, allowing the gas to be ignited by the ignition device. The remaining air volume sweeps outwards, scouring the combustion chamber and cooling it. Openings at different heights in the combustion chamber (secondary, tertiary, and quaternary air supply inlets) introduce external airflow into the low-pressure combustion chamber. The air volume introduced into the combustion chamber is controlled by the opening diameter, progressively reducing the flue gas temperature and simultaneously compressing the flame size.

[0017] The longitudinal sweeping air enters the combustion chamber from bottom to top through the openings (secondary air supply port, tertiary air supply port, and quaternary air supply port) along the height direction of the combustion chamber cylinder. It mixes directly with the high-temperature flue gas to cool it down and compresses the flame size to prevent the flame from being blown out.

[0018] The air supply volume does not need to change with the gas supply volume. This is determined by the mechanical structure design of the outer ring plate, middle ring plate, inner ring plate, secondary air supply port, tertiary air supply port, and quaternary air supply port.

[0019] The invention features high integration, small size, light weight, and easy replacement of the key component, the combustion chamber. Attached Figure Description

[0020] Figure 1 A structural diagram of a multi-stage air supply device for a gas combustion unit;

[0021] Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure. Detailed Implementation

[0022] like Figure 1 As shown, a multi-stage air supply device for a marine gas combustion unit includes one or more fans 1. The fans 1 are connected to a mixing box 4 via flexible connectors 2 and a backflow preventer 3. A grid plate 5 is provided above the air outlet of the mixing box 4. A combustion chamber cylinder 6 is located above the grid plate 5. The air supplied by the fans 1 is mixed in the mixing box 4 and discharged to the primary air supply port of the combustion chamber cylinder 6 after passing through the outlet grid plate 5. The grid plate 5 can withstand a certain load and can play a role in uniformizing the air velocity.

[0023] like Figure 2 As shown, the bottom primary air supply port of the combustion chamber cylinder 6 is provided with an outer ring plate 12, a middle ring plate 11, an inner ring plate 10, and a burner 7 in sequence from the outside to the inside.

[0024] The primary air supply is distributed through the inner ring plate 10 at the bottom of the combustion chamber. A small portion of the air is injected through the inner ring plate 10 to the gas injection root of the burner 7. On the one hand, the air mixes with the gas, facilitating effective ignition by the ignition device fixed on the inner ring plate 10. On the other hand, it forms regional backflow to prevent flameout. The inner ring plate 10 is made of heat-resistant steel that can withstand 700℃, which meets the usage requirements.

[0025] The primary air supply is distributed through the intermediate ring plate 11 and the outer ring plate 12 of the combustion chamber. A suitable amount of air is injected through the intermediate ring plate 11 and the gap between the intermediate ring plate 11 and the outer ring plate 12 to the periphery of the root flame, directly mixing with the high-temperature flue gas generated by combustion to cool it down and compress the flame size, increasing the distance between the outer flame and the inner wall of the combustion chamber cylinder 6. The remaining air sweeps along the outside of the combustion chamber cylinder 6, thus protecting the combustion chamber cylinder 6. The intermediate ring plate 11 and the root cylinder of the combustion chamber cylinder 6 are made of heat-resistant steel that can withstand 600℃, which meets the usage requirements.

[0026] Located above the burner 7, the side wall of the combustion chamber cylinder 6 is provided with a secondary air supply port, a tertiary air supply port, and a quaternary air supply port from bottom to top;

[0027] The secondary air supply enters the combustion chamber from the side through the secondary air supply port at the lower position of the combustion chamber cylinder 6. The height of the secondary air supply port is about 0.2 of the total height of the combustion chamber and accounts for about 50% of the total air volume. The huge air volume compresses the size of the bottom flame and reduces the wall temperature of the combustion chamber cylinder 6 to less than 500°C, thus achieving the purpose of controlling the size of the device and protecting the combustion chamber.

[0028] The third-stage air supply enters through the lateral opening of the third-stage air supply port in the middle of the combustion chamber cylinder 6. The height of the third-stage air supply port is about 0.4 of the total height of the combustion chamber and about 12.5% ​​of the total air volume. It compresses the flame expansion part in the middle section to achieve the same purpose as the second-stage air supply.

[0029] The fourth-stage air supply enters from the lateral opening of the fourth-stage air supply port at the high position of the combustion chamber cylinder 6. The opening height of the fourth-stage air supply port accounts for about 0.65 of the total height of the combustion chamber and about 12.5% ​​of the total air volume. It compresses the high-level expansion part of the flame to achieve the same purpose.

[0030] An exhaust tower 8 is installed outside the combustion chamber cylinder 6.

[0031] A reinforcing ring plate 9 is installed at the secondary air supply inlet of the combustion chamber cylinder 6. The entire air distribution uses structural openings to distribute airflow and cool the combustion chamber, which affects the strength of the combustion chamber and reduces its ability to control deformation due to high-temperature expansion under operating conditions. To address this drawback, the area near the secondary air supply opening should be reinforced during the design phase. This can be achieved by welding the reinforcing ring plate 9 to control deformation.

Claims

1. A multi-stage air supply device for a ship's gas combustion unit, characterized in that, Includes one or more fans (1), the fans (1) are connected to the mixing box (4) through flexible connectors (2) and check dampers (3), and a grid plate (5) is provided above the air outlet of the mixing box (4); the combustion chamber cylinder (6) is above the grid plate (5); the air provided by the fans (1) is mixed in the mixing box (4), and discharged to the first-stage air supply port at the bottom of the combustion chamber cylinder (6) after passing through the outlet grid plate (5); The bottom primary air supply port of the combustion chamber cylinder (6) is provided with an outer ring plate (12), a middle ring plate (11), an inner ring plate (10), and a burner (7) in sequence from the outside to the inside. Located above the burner (7), the side wall of the combustion chamber cylinder (6) is provided with a secondary air supply port, a tertiary air supply port and a quaternary air supply port from bottom to top; The primary air supply is distributed through the inner ring plate (10) at the bottom of the combustion chamber. Part of the air is injected through the inner ring plate (10) to the root of the gas injection of the burner (7). The air and gas are mixed and used for effective ignition by the ignition device fixed on the inner ring plate (10), and regional backflow is formed to prevent flameout. The primary air supply is distributed through the intermediate ring plate (11) and outer ring plate (12) of the combustion chamber. The air is injected through the intermediate ring plate (11) and the gap between the intermediate ring plate (11) and the outer ring plate (12) to the periphery of the root flame. It mixes directly with the high-temperature flue gas generated by combustion to cool it down and compress the flame size, increasing the distance between the outer flame and the inner wall of the combustion chamber cylinder (6). The remaining air sweeps along the outside of the combustion chamber cylinder (6) to form the secondary, tertiary and quaternary air supply to protect the combustion chamber cylinder (6). An exhaust tower (8) is provided outside the combustion chamber cylinder (6).

2. A multi-stage air supply device for a ship's gas combustion unit according to claim 1, characterized in that, The height of the secondary air supply port is 0.2 of the total height of the combustion chamber cylinder (6), and the secondary air supply accounts for 50% of the total air volume. The large air volume is used to compress the size of the bottom flame and reduce the wall temperature of the combustion chamber cylinder (6) to less than 500°C, thereby achieving the purpose of controlling the size of the device and protecting the combustion chamber cylinder (6). The height of the three-stage air supply outlet is 0.4 of the total height of the combustion chamber cylinder (6) and accounts for 12.5% ​​of the total air volume, which compresses the flame expansion part in the middle section; The opening height of the fourth-stage air supply port is 0.65 of the total height of the combustion chamber cylinder (6) and accounts for 12.5% ​​of the total air volume, which compresses the high-level expansion part of the flame.

3. A multi-stage air supply device for a ship's gas combustion unit according to claim 1, characterized in that, The combustion chamber cylinder (6) is provided with a reinforcing ring plate (9) at the secondary air supply port.

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