A multi-stage submerged combustion system and control method

Abstract

The present application relates to the technical field of submerged combustion gasifier, in particular to a kind of multistage submerged combustion system and control method, including ignition burner and main burner, the main burner includes multistage arrangement of burner nozzle, the spacing between adjacent burner nozzles of different levels and the spacing of adjacent burner nozzles of the same level make flame sector interference, the burner nozzle is provided with shroud, the shroud is opened with the opening of flame passing through.To maintain continuous, stable, safe combustion condition, gas concentration must be within the flammable concentration range of fuel gas, so shroud is set, the influence of a large amount of rotational flow air on ignition fuel gas concentration and ignition flame stability is reduced, and the flame sector of each burner nozzle and adjacent burner nozzle has intersection, ensure that local fuel gas concentration does not decrease, further stabilize flame, ensure high flame stability.

Description

Technical Field

[0001] This invention relates to the field of submerged combustion gasifier technology, specifically to a multi-stage submerged combustion system and control method. Background Technology

[0002] Because SCV submerged combustion vaporizers are unaffected by seawater and atmospheric temperatures, they can ignite and start up quickly, and can rapidly adjust within a load range of 10%-100%, making them particularly suitable for emergency peak shaving and winter supply assurance in LNG receiving terminals or peak shaving stations. However, the SCV submerged combustion vaporizers currently operating in LNG receiving terminals or peak shaving stations use imported burners, which generally suffer from low first-time ignition success rates, small load regulation ratios, and unstable combustion.

[0003] In an SCV submerged combustion gasifier, the combustion chamber outlet is submerged in water. For combustion to occur, the fuel gas and air entering the combustion chamber must overcome liquid level resistance and back pressure. Before ignition, a fan must be activated to force water out of the combustion chamber and bubbler, resulting in a high wind speed at the central burner. This can easily disperse the fuel gas, causing a localized decrease in fuel gas concentration and making ignition difficult. Simultaneously, the high-temperature flue gas generated during combustion exits from below the liquid surface. The bubbling action of the bubbler tube creates intense agitation, causing changes in the liquid level and pressure within the combustion chamber. This leads to variations in air and fuel gas flow rates, resulting in changes in the localized fuel mixture ratio and potentially causing a localized decrease in fuel gas concentration. This can result in burner flameout and extinguishing, affecting combustion stability.

[0004] SCV submerged combustion gasifiers need to operate at low loads of around 10%. In order to maintain a constant water bath level, a large amount of air must be maintained to overcome the water bath back pressure, resulting in a large excess air coefficient and a low fuel gas concentration. This makes the flame combustion unstable under low load conditions, and the load regulation ratio of the SCV submerged burner is small.

[0005] The design of the central lamp and burner in the existing combustion system is unreasonable and lacks strong airflow protection measures. It cannot effectively guarantee the fuel gas concentration required for normal combustion of the central lamp and burner under various operating conditions. Therefore, the existing SCV burners generally have the disadvantages of low first ignition success rate, small load regulation ratio and inability to achieve stable combustion. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-stage submerged combustion system and control method, which solves the problems of unreasonable design of the center lamp and burner in existing combustion systems, lack of strong airflow protection measures, and inability to effectively guarantee the fuel gas concentration required for normal combustion of the lamp and burner under various operating conditions. Therefore, existing SCV burners generally suffer from low first-time ignition success rate, small load regulation ratio, and inability to achieve stable combustion.

[0007] This invention discloses a multi-stage immersion combustion system, including an ignition burner and a main burner. The main burner includes burners arranged in multiple stages. The spacing between adjacent burners in different stages and the spacing between adjacent burners in the same stage cause the flame fan shape to interfere. A protective cover is provided on the burner, and the protective cover has an opening to allow the flame to pass through.

[0008] Due to the unique structure of submerged burners, even under normal combustion conditions, the unstable water bath level causes pressure fluctuations within the combustion chamber, resulting in continuous changes in the fuel gas concentration. To maintain continuous, stable, and safe combustion, the fuel gas concentration must remain within the combustible concentration range. Therefore, a protective shroud is installed to reduce the impact of large amounts of swirling air on the ignition fuel gas concentration and flame stability. Furthermore, the flame fan shape of each burner intersects with that of adjacent burners to ensure that the local fuel gas concentration does not decrease, further stabilizing the flame and ensuring high flame combustion stability.

[0009] Furthermore, the adjacent flames that form the interference intersect at a rate of 40% to 60%.

[0010] Furthermore, the multi-stage burner arrangement has at least two stages.

[0011] Furthermore, the multi-stage burner arrangement is three-stage, consisting of a first-stage burner, a second-stage burner, and a third-stage burner arranged from the center of the main burner outwards.

[0012] Furthermore, the primary burner is a continuous lamp, which is located at the center of the main burner.

[0013] Furthermore, the secondary burner is an inner ring burner, and the tertiary burner is an outer ring burner.

[0014] Furthermore, the secondary and tertiary burners are arranged in concentric circles.

[0015] Furthermore, the number of the three-stage burners is twice the number of the two-stage burners.

[0016] Furthermore, a fuel gas system is provided on top of the main burner.

[0017] Fuel gas is supplied to the multi-stage burners by setting up a fuel gas system.

[0018] Furthermore, a central combustion chamber is provided below the main burner, and a lower single-layer combustion chamber is provided below the central combustion chamber.

[0019] Furthermore, an air system is provided on one side of the main burner.

[0020] Furthermore, a Roots blower is installed within the air system.

[0021] By installing a Roots blower, pressurized air enters the combustion chamber to overcome liquid level resistance and back pressure, and water is forced into the middle combustion chamber before ignition, which facilitates ignition and meets the combustion air requirements during normal operation.

[0022] Furthermore, a cooling water circulation system is installed outside the central combustion chamber.

[0023] Since the lower single-layer combustion chamber is submerged in a water bath, while the middle combustion chamber is not submerged, the combustion chamber is not equipped with an internal heat-resistant lining for insulation. Instead, a water jacket is installed outside the combustion chamber for heat dissipation. The cooling circulating water system provides circulating cooling water to the jacket of the combustion system to ensure that the temperature of the outer wall material of the combustion chamber is controlled within a suitable range.

[0024] A multi-stage submerged combustion control method involves introducing a large amount of pressurized air to drain the water from the combustion chamber, then introducing ignition fuel gas and ignition air to ignite the burners, and activating multi-stage burners according to different loads. This staged fuel gas supply technology effectively reduces the highest flame temperature and the highest temperature range, thus significantly reducing nitrogen oxide emissions.

[0025] Furthermore, the multi-stage burner arrangement is three-stage, consisting of a primary burner, a secondary burner, and a tertiary burner.

[0026] Furthermore, only a single-stage burner is used at 10% load; a single-stage and a two-stage burner are used at 10%-45% load; and a single-stage, a two-stage, and a three-stage burner are used at 45%-110% load. This setup also avoids the problem of low fuel gas concentration in the burner at low loads, ensuring flame stability.

[0027] Furthermore, the fuel gas volume concentration at the burner is 5% to 15%.

[0028] The volume concentration of fuel gas is 5% to 15%, which is within the explosion threshold of methane.

[0029] For specific gas types, structural parameters, and combustion conditions, air pressure and gas pressure are constant. If the supply pressures of air and gas are the same, the gas concentration entering the combustion chamber remains unchanged when the combustion chamber pressure changes. However, if the supply pressures of air and gas are different, the gas concentration entering the combustion chamber will change when the combustion chamber pressure changes. If the combustion chamber pressure fluctuation causes the gas concentration to exceed the combustible concentration range, combustion cannot continue, leading to flame extinction. Therefore, controlling the fuel gas concentration at the burner is crucial for stable combustion in submerged burners.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. Due to the unique structure of submerged burners, even under normal combustion conditions, the unstable water bath level causes pressure fluctuations within the combustion chamber, resulting in continuous changes in the fuel gas concentration. To maintain continuous, stable, and safe combustion, the fuel gas concentration must be within the combustible concentration range. Therefore, a protective shroud is installed to reduce the impact of large amounts of swirling air on the ignition fuel gas concentration and ignition flame stability. Furthermore, the flame fan shape of each burner intersects with that of adjacent burners to ensure that the local fuel gas concentration does not decrease, further stabilizing the flame and ensuring high flame combustion stability.

[0032] 2. The use of staged fuel gas supply technology effectively reduces the highest temperature and the highest temperature range of the combustion flame, thereby effectively reducing the generation of nitrogen oxides;

[0033] 3. The multi-stage burner arrangement avoids the problem of low fuel gas concentration in low-load burners, ensuring flame stability. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the multi-stage immersion combustion system of the present invention.

[0036] In the above figures, the meanings of each mark are as follows: 1-Ignition burner, 2-Main burner, 3-Enclosure, 4-First stage burner, 5-Second stage burner, 6-Third stage burner, 7-Fuel gas system, 8-Middle combustion chamber, 9-Lower single-layer combustion chamber, 10-Air system, 11-Cooling circulating water system. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0038] A multi-stage submerged combustion control method involves introducing a large amount of pressurized air to drain the water from the combustion chamber, then introducing ignition fuel gas and ignition air to ignite the burner 1. A multi-stage arrangement of burners is activated according to different loads. The multi-stage arrangement consists of three stages: a primary burner 4, a secondary burner 5, and a tertiary burner 6. At 10% load, only the primary burner 4 is used; at 10%-45% load, primary burner 4 and secondary burner 5 are used; and at 45%-110% load, primary burner 4, secondary burner 5, and tertiary burner 6 are used. This configuration also avoids the problem of low fuel gas concentration at low loads, ensuring flame stability. The fuel gas volume concentration at the burners is 5%–15%.

[0039] Example 1

[0040] The multi-stage submerged combustion system using the above method in this embodiment has the following specific structure: Figure 1 As shown, the device includes an ignition burner 1 and a main burner 2. The main burner 2 includes multi-stage burners. The spacing between adjacent burners of different stages and the spacing between adjacent burners of the same stage cause the flame fan shape to interfere. A protective cover 3 is provided on the burner, and the protective cover 3 has an opening that allows the flame to pass through. The adjacent flames that cause interference intersect at a rate of 40% to 60%. The multi-stage burners are arranged in three stages. Centered on the center of the main burner 2, from the inside out, they are a first-stage burner 4, a second-stage burner 5, and a third-stage burner 6. The first-stage burner 4 is a continuous lamp located at the center of the main burner 2. The second-stage burners 5 and the third-stage burners 6 are arranged in concentric circles. The number of third-stage burners 6 is twice the number of second-stage burners 5. The second-stage burners 5 are inner ring burners, and the third-stage burners 6 are outer ring burners.

[0041] Due to the unique structure of submerged burners, even under normal combustion conditions, the unstable water bath level causes pressure fluctuations within the combustion chamber, resulting in continuous changes in the fuel gas concentration. To maintain continuous, stable, and safe combustion, the fuel gas concentration must remain within the combustible concentration range. Therefore, a protective shroud 3 is installed to reduce the impact of a large amount of swirling air on the ignition fuel gas concentration and ignition flame stability. Furthermore, the flame fan shape of each burner intersects with that of adjacent burners, ensuring that the local fuel gas concentration does not decrease, further stabilizing the flame and guaranteeing high flame combustion stability.

[0042] Example 2

[0043] In this embodiment, which is a preferred embodiment of the present invention, a multi-stage submerged combustion system is improved based on embodiment 1 as follows: a fuel gas system 7 is provided at the top of the main burner 2, a middle combustion chamber 8 is provided below the main burner 2, a lower single-layer combustion chamber 9 is provided below the middle combustion chamber 8, an air system 10 is provided on one side of the main burner 2, a Roots blower is provided inside the air system 10, and a cooling circulating water system 11 is provided outside the middle combustion chamber 8.

[0044] Fuel gas is supplied to the multi-stage burners by setting up fuel gas system 7.

[0045] By installing a Roots blower, pressurized air enters the combustion chamber to overcome liquid level resistance and back pressure, and water is forced into the middle combustion chamber 8 before ignition, which facilitates ignition and meets the combustion air requirements during normal operation.

[0046] Since the lower single-layer combustion chamber 9 is submerged in the water bath, while the middle combustion chamber 8 is not submerged in the water bath, the combustion chamber is not equipped with an internal heat-resistant lining for heat insulation. Instead, a water jacket is installed outside the combustion chamber for heat dissipation. The cooling circulating water system 11 provides circulating cooling water to the jacket of the combustion system to ensure that the temperature of the outer wall material of the combustion chamber is controlled within a suitable range.

[0047] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.

Claims

1. A multi-stage submerged combustion system, characterized in that: It includes an ignition burner (1) and a main burner (2). The main burner (2) includes multi-stage burners. The spacing between adjacent burners of different stages and the spacing between adjacent burners of the same stage cause the flame fan shape to interfere. A protective cover (3) is provided on the burner. The protective cover (3) has an opening that allows the flame to pass through. The protective cover reduces the influence of a large amount of swirling air on the concentration of ignition fuel gas and the stability of ignition flame. The adjacent flames that form interference intersect at a rate of 40% to 60%. The multi-stage burners are three-stage, with the center of the main burner (2) as the center, and from the inside out, they are a first-stage burner (4), a second-stage burner (5), and a third-stage burner (6).

2. The multi-stage submerged combustion system according to claim 1, characterized in that: The primary burner (4) is a continuous lamp, which is located at the center of the main burner (2).

3. The multi-stage submerged combustion system according to claim 1, characterized in that: The secondary burner (5) and the tertiary burner (6) are arranged in concentric circles.

4. The multi-stage submerged combustion system according to claim 1, characterized in that: The main burner (2) is equipped with a fuel gas system (7) on top.

5. A multi-stage submerged combustion system according to claim 1, characterized in that: A middle combustion chamber (8) is provided below the main burner (2), and a lower single-layer combustion chamber (9) is provided below the middle combustion chamber (8).

6. A control method for a multi-stage submerged combustion system according to any one of claims 1-5, characterized in that: A large amount of pressurized air is introduced to drain the water from the combustion chamber. Ignition fuel gas and ignition air are introduced to ignite the ignition burner (1). The multi-stage burners are turned on according to different loads.

7. The control method for a multi-stage submerged combustion system according to claim 6, characterized in that: The multi-stage burner arrangement consists of three stages: a primary burner (4), a secondary burner (5), and a tertiary burner (6).

8. The control method for a multi-stage submerged combustion system according to claim 7, characterized in that: When the load is 10%, only the first-stage burner (4) is used; when the load is 10%-45%, the first-stage burner (4) and the second-stage burner (5) are used; when the load is 45%-110%, the first-stage burner (4), the second-stage burner (5) and the third-stage burner (6) are used.

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