Multi-stage submerged combustion system and control method

Abstract

The invention relates to the technical field of submerged combustion type gasifiers, in particular to a multi-stage submerged combustion system and a control method.The multi-stage submerged combustion system comprises an ignition burner and a main burner, the main burner comprises burners arranged in multiple stages, and the interval between every two adjacent burners in different stages and the interval between every two adjacent burners in the same stage enable flame sectors to form interference; a protective cover is arranged on the burner, and an opening allowing flame to penetrate through is formed in the protective cover. In order to maintain a continuous, stable and safe combustion working condition, the gas concentration must be within the combustible concentration range of gas, so that the shield is arranged, the influence of a large amount of rotational flow air on the ignition fuel gas concentration and the ignition flame stability is reduced, and the flame sectors of each burner and the adjacent burner are intersected, so that the local fuel gas concentration is not reduced, and the combustion efficiency is improved. The flame is further stabilized, and high flame combustion stability is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of submerged combustion gasifiers, and in particular to a multi-stage submerged combustion system and a control method. Background Art

[0002] Since the SCV submerged combustion gasifier is not affected by seawater and atmospheric temperature, it can be quickly ignited and started, and can be quickly adjusted within the load range of 10%-100%, it is particularly suitable for emergency peak load regulation and winter supply guarantee at LNG receiving stations or peak load regulation stations. However, the burners used in the SCV submerged combustion gasifiers currently operated at LNG receiving stations or peak load regulation stations are imported, and generally have the disadvantages of low first-time ignition success rate, small load regulation ratio, and inability to burn stably.

[0003] The combustion chamber outlet of the SCV submerged combustion gasifier is immersed in water. The gas and air entering the combustion chamber need to overcome the liquid level resistance and back pressure. Before ignition, the fan needs to be started to press the water out of the combustion chamber and bubbler, resulting in a high wind speed at the center of the long-light lamp, which is easy to blow away the fuel gas, reduce the local fuel gas concentration, and make ignition difficult. At the same time, the high-temperature flue gas generated by the combustion is discharged from below the liquid surface, and the bubbling effect of the bubbler tube produces a violent stirring effect. The liquid surface position changes, causing the pressure in the combustion chamber to fluctuate, causing changes in air flow and gas flow, resulting in changes in the local mixing ratio of the fuel, and it is also easy to cause the local fuel gas concentration to decrease, causing the burner to flame out and affect the stability of combustion.

[0004] The SCV submerged combustion gasifier needs to operate at a low load of about 10%. In order to keep the water bath level constant, a large amount of air is needed to overcome the water bath back pressure, resulting in a large excess air coefficient and reduced fuel gas concentration, making the flame combustion unstable under low load conditions and the SCV submerged burner load adjustment ratio small.

[0005] The design method of the central pilot lamp and burner of the existing combustion system is unreasonable, lacks strong airflow protection measures, and cannot effectively guarantee the fuel gas concentration required for the normal combustion of the pilot lamp and burner under various operating conditions. Therefore, the existing SCV burners generally have the shortcomings of low one-time ignition success rate, small load regulation ratio, and inability to burn stably. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-stage submerged combustion system and control method to solve the problems in the prior art that the design method of the central pilot lamp and the burner of the existing combustion system is unreasonable, there is a lack of strong airflow protection measures, and it is impossible to effectively ensure the fuel gas concentration required for the normal combustion of the pilot lamp and the burner under various working conditions. Therefore, the existing SCV burners generally have the technical problems of low one-time ignition success rate, small load regulation ratio, and inability to burn stably.

[0007] The invention discloses a multi-stage submerged combustion system, comprising an ignition burner and a main burner. The main burner comprises burners arranged in multiple stages. The distances between adjacent burners at different stages and the distances between adjacent burners at the same stage cause the flame fan to form interference. A shield is arranged on the burner, and the shield has an opening for the flame to pass through.

[0008] Due to the particularity of the structure of the submerged burner, even in normal combustion conditions, the unstable water bath liquid level causes the pressure in the combustion chamber to fluctuate, and the gas concentration in the combustion chamber changes continuously. To maintain continuous, stable, and safe combustion conditions, the gas concentration must be within the combustible concentration range of the gas, so a shield is set to reduce the impact of a large amount of swirling air on the ignition fuel gas concentration and the ignition flame stability, and the flame fan of each burner and the adjacent burner have intersections to ensure that the local fuel gas concentration does not decrease, further stabilize the flame, and ensure high flame combustion stability.

[0009] Furthermore, the adjacent flames that form interference have an intersection 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, with the center of the main burner at the center, from the inside to the outside, there are a first-stage burner, a second-stage burner and a third-stage burner.

[0012] Furthermore, the first-stage burner is a permanent lamp, and the permanent lamp 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 burner and the tertiary burner are arranged in concentric circles.

[0015] Furthermore, the number of the third-stage burners is twice the number of the second-stage burners.

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

[0017] A fuel gas system is provided to provide fuel gas for the multi-stage burners.

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

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

[0020] Furthermore, a Roots blower is provided in the air system.

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

[0022] Furthermore, a cooling circulating water system is arranged outside the middle combustion chamber.

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

[0024] A multi-stage submerged combustion control method, which introduces a large amount of pressurized air to drain the water in the combustion chamber, introduces ignition fuel gas and ignition air to ignite the ignition burner, and opens the multi-stage burner according to different loads. The fuel gas staged supply technology is used to effectively reduce the maximum temperature and the maximum temperature area of ​​the combustion flame, and effectively reduce the generation of nitrogen oxides.

[0025] Furthermore, the multi-stage burner arrangement has three stages, namely, a primary burner, a secondary burner and a tertiary burner.

[0026] Furthermore, when the load is 10%, only the primary burner is used, when the load is 10%-45%, the primary burner and the secondary burner are used, and when the load is 45%-110%, the primary burner, the secondary burner and the tertiary burner are used. This setting also avoids the problem of low fuel gas concentration in low-load burners and ensures the stability of the flame.

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

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

[0029] For specific gas types, structural parameters and combustion conditions, the air pressure and gas pressure are fixed values. If the air and gas supply pressures are the same, when the combustion chamber pressure value changes, the gas concentration entering the combustion chamber remains unchanged; if the air and gas supply pressures are different, when the combustion chamber pressure value changes, the gas concentration entering the combustion chamber will change. When the combustion chamber pressure fluctuation causes the gas concentration to exceed the combustible concentration range, the combustion cannot continue, causing the flame to go out. Therefore, the control of fuel gas concentration at the burner nozzle becomes the key to stable combustion of the submerged burner.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. Due to the particularity of the structure of the submerged burner, even in normal combustion conditions, the unstable influence of the water bath liquid level causes the pressure in the combustion chamber to fluctuate, and the gas concentration in the combustion chamber changes continuously. To maintain continuous, stable, and safe combustion conditions, the gas concentration must be within the combustible concentration range of the gas, so a shield is set to reduce the influence of a large amount of swirling air on the ignition fuel gas concentration and the ignition flame stability, and the flame fan of each burner and the adjacent burner have intersections to ensure that the local fuel gas concentration does not decrease, further stabilize the flame, and ensure high flame combustion stability;

[0032] 2. The fuel gas staged supply technology is adopted to effectively reduce the maximum temperature and the maximum temperature area of ​​the combustion flame, and effectively reduce the generation of nitrogen oxides;

[0033] 3. The multi-stage burner arrangement avoids the problem of low fuel gas concentration in low-load burners and ensures the stability of the flame. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only represent some embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 It is a schematic diagram of the structure of the multi-stage submerged combustion system of the present invention.

[0036] In the above drawings, the meanings of the various marks are: 1-ignition burner, 2-main burner, 3-shield, 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 DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0038] A multi-stage submerged combustion control method, a large amount of pressurized air is introduced to drain the water in the combustion chamber, ignition fuel gas and ignition air are introduced to ignite the ignition burner 1, and the multi-stage burners are opened according to different loads. The multi-stage burners are three-stage, namely, a primary burner 4, a secondary burner 5 and a tertiary burner 6. When the load is 10%, only the primary burner 4 is used, when the load is 10%-45%, the primary burner 4 and the secondary burner 5 are used, and when the load is 45%-110%, the primary burner 4, the secondary burner 5 and the tertiary burner 6 are used. This setting also avoids the problem of low fuel gas concentration in low-load burners and ensures the stability of the flame. The volume concentration of the fuel gas at the burner is 5% to 15%.

[0039] Example 1

[0040] The multi-stage submerged combustion system of the above method adopted in this embodiment has a specific structure as follows: Figure 1 As shown, it includes an ignition burner 1 and a main burner 2, the main burner 2 includes a multi-stage burner arrangement, the spacing between adjacent burners of different stages and the spacing between adjacent burners of the same stage cause the flame fan to interfere, a shield 3 is provided on the burner, the shield 3 has an opening for the flame to pass through, the adjacent flames that form interference intersect at 40% to 60%, the multi-stage burner arrangement is three-stage, with the center at the center of the main burner 2, from the inside to the outside are a primary burner 4, a secondary burner 5 and a tertiary burner 6, the primary burner 4 is a long-burning lamp, the long-burning lamp is located at the center of the main burner 2, the secondary burner 5 and the tertiary burner 6 are arranged in concentric circles, the number of the tertiary burner 6 is twice the number of the secondary burner 5, the secondary burner 5 is an inner ring burner, and the tertiary burner 6 is an outer ring burner.

[0041] Due to the particularity of the structure of the submerged burner, even in normal combustion conditions, the unstable influence of the water bath liquid level causes the pressure in the combustion chamber to fluctuate, and the gas concentration in the combustion chamber changes continuously. To maintain continuous, stable and safe combustion conditions, the gas concentration must be within the combustible concentration range of the gas, so a shield 3 is provided to reduce the influence of a large amount of swirling air on the ignition fuel gas concentration and the ignition flame stability, and the flame fan of each burner and the adjacent burner have intersections to ensure that the local fuel gas concentration does not decrease, further stabilize the flame, and ensure high flame combustion stability.

[0042] Example 2

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

[0044] A fuel gas system 7 is provided to provide fuel gas for the multi-stage burners.

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

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

[0047] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A multi-stage submerged combustion system, characterized in that: The invention comprises an ignition burner (1) and a main burner (2), wherein the main burner (2) comprises burners arranged in multiple stages, the distances between adjacent burners at different stages and the distances between adjacent burners at the same stage make the flame fan-shaped form interference, and a shield (3) is arranged on the burner, and the shield (3) has an opening for the flame to pass through.

2. A multi-stage submerged combustion system according to claim 1, characterized in that: The adjacent flames forming interference have an intersection of 40% to 60%.

3. A multi-stage submerged combustion system according to claim 2, characterized in that: The multi-stage burner arrangement has three stages, with the center of the main burner (2) as the center, and from the inside to the outside, there are a first-stage burner (4), a second-stage burner (5) and a third-stage burner (6).

4. A multi-stage submerged combustion system according to claim 3, characterized in that: The first-stage burner (4) is a permanent lamp, and the permanent lamp is located at the center of the main burner (2).

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

6. A multi-stage submerged combustion system according to claim 1, characterized in that: A fuel gas system (7) is arranged on the top of the main burner (2).

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

8. A control method for a multi-stage submerged combustion system according to any one of claims 1 to 7, characterized in that: A large amount of pressurized air is introduced to drain the water in the combustion chamber, and ignition fuel gas and ignition air are introduced to ignite the ignition burner (1), and the burners arranged in multiple stages are opened according to different loads.

9. The control method of a multi-stage submerged combustion system according to claim 8, characterized in that: The multi-stage burner arrangement has three stages, namely a primary burner (4), a secondary burner (5) and a tertiary burner (6).

10. The control method of a multi-stage submerged combustion system according to claim 9, characterized in that: When the load is 10%, only the primary burner (4) is used; when the load is 10%-45%, the primary burner (4) and the secondary burner (5) are used; when the load is 45%-110%, the primary burner (4), the secondary burner (5) and the tertiary burner (6) are used.

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