A marine BOG gas incineration device and a control method thereof

Abstract

The application relates to a marine BOG gas incineration device and a control method thereof. The incineration device comprises a natural gas pipeline system, an auxiliary fuel gas pipeline system, an air supply pipeline system and a GCU incineration device; the natural gas pipeline system comprises a natural gas main pipeline and an ignition branch pipeline, a first combustion branch pipeline and a second combustion branch pipeline, and a diffusion branch pipeline is arranged on the natural gas main pipeline; the auxiliary fuel gas pipeline system comprises an auxiliary fuel gas pipeline, and the auxiliary fuel gas pipeline is connected with the ignition branch pipeline, the first combustion branch pipeline and the second combustion branch pipeline in series; the air supply pipeline system comprises an air supply fan and an air supply pipeline; the GCU incineration device comprises a wind distribution chamber, a treatment chamber, a combustion chamber and a burner, the treatment chamber is communicated with the wind distribution chamber, the combustion chamber is communicated with the treatment chamber, the burner is arranged in the combustion chamber, and the air supply pipeline is communicated with the wind distribution chamber. The application solves the problem that the prior art cannot incinerate three kinds of BOG gas, i.e. low-temperature and low-pressure gas on an LNG ship, high-pressure and normal-temperature gas and low-concentration mixed gas.

Description

Technical Field

[0001] This application relates to the field of gas emissions in LNG transportation, and in particular to a marine BOG gas incineration device and its control method. Background Technology

[0002] Liquefied Natural Gas (LNG) is a colorless, transparent liquid obtained by cooling natural gas, which is mainly composed of methane, to approximately -162°C, and has a volume approximately 1 / 600th that of natural gas. Therefore, natural gas can be transported efficiently by liquefying it. Since natural gas liquefies at extremely low temperatures of -163°C under atmospheric pressure, LNG can vaporize at atmospheric pressure or even at temperatures slightly above -163°C. Despite thermal insulation of LNG carriers, LNG-FPSOs, RVs, and similar LNG storage tanks, the LNG naturally evaporates within the tank due to the continuous transfer of heat from the outside. This results in the generation of boil-off gas (BOG) within the LNG tank.

[0003] The gases emitted by LNG carriers come from the following sources: 1. During the LNG carrier's voyage, liquefied natural gas (LNG) in the cargo tanks continuously evaporates. To prevent excessive pressure in the cargo tanks, this gas needs to be released to regulate the tank pressure. Therefore, the first type of emitted gas is low-temperature, low-pressure natural gas. 2. Dual-fuel engines require natural gas as fuel. Typically, the evaporated gas is compressed using a compressor, or LNG is vaporized for use. When not in use, the remaining natural gas in the buffer tanks in the pipelines needs to be released. Therefore, the second type of emitted gas is high-pressure, room-temperature natural gas. 3. After unloading, LNG carriers need to undergo inert gas purging before refueling with LNG. The inert gas purging and refueling processes generate a nitrogen / natural gas mixture, which needs to be released. Depending on the process, the CH4 concentration will increase from 0% to 100% or decrease from 100% to 0%. Therefore, the third type of emitted gas is a mixture of gases with variable temperature, pressure, and composition. This third type of gas is difficult to handle when the methane concentration is low due to its low calorific value.

[0004] Due to the significant variations in the temperature, pressure, and composition of the exhaust gas, conventional gas combustion units (GCUs) cannot simultaneously meet the requirements of cargo tank pressure regulation, high-pressure gas stabilization, and low-concentration methane combustion to achieve zero methane emissions. Therefore, it is necessary to provide an incinerator and a marine natural gas combustion device to at least partially solve the above problems. Summary of the Invention

[0005] To address the problem that existing gas combustion devices cannot simultaneously meet the requirements of liquid cargo tank pressure regulation, high-pressure gas stabilization, and low-concentration methane combustion, this application provides a marine BOG gas combustion device and its control method.

[0006] Firstly, the marine BOG gas combustion device provided in this application adopts the following technical solution:

[0007] A marine BOG gas combustion device includes a natural gas pipeline system, an auxiliary fuel gas pipeline system, a combustion air pipeline system, and a GCU combustion unit.

[0008] The natural gas pipeline system includes a main natural gas pipeline and an ignition branch pipeline, a first combustion branch pipeline, and a second combustion branch pipeline connected in series with the main natural gas pipeline. The ignition branch pipeline, the first combustion branch pipeline, and the second combustion branch pipeline are connected in parallel. The main natural gas pipeline is equipped with a gas concentration detection device, a pressure monitoring device, and a first control valve group for controlling the on / off state of the main natural gas pipeline. The main natural gas pipeline is equipped with a venting branch pipeline, and a normally open venting valve is provided on the venting branch pipeline. The ignition branch pipeline, the first combustion branch pipeline, and the second combustion branch pipeline are each equipped with a pipeline on / off valve.

[0009] The auxiliary fuel gas pipeline system includes an auxiliary gas pipeline and a second control valve group for controlling the on / off state of the auxiliary gas pipeline. The auxiliary gas pipeline is connected in parallel with the main natural gas pipeline and in series with the ignition branch pipeline, the first combustion branch pipeline and the second combustion branch pipeline, respectively.

[0010] The combustion air duct system includes a combustion air blower and combustion air ducts connected to the combustion air blower;

[0011] The GCU incineration device includes an air distribution chamber, a processing chamber, a combustion chamber, and a burner. The processing chamber is located above the air distribution chamber and the two are interconnected. The combustion chamber is located inside the processing chamber and the two are interconnected. The burner is located inside the combustion chamber. The ignition branch pipe is connected to the ignition module of the burner. The first combustion branch pipe and the second combustion branch pipe are respectively connected to the main combustion module of the burner. The combustion air duct is connected to the air distribution chamber.

[0012] By adopting the above technical solution, using a pressure monitoring device and three parallel branches for ignition, primary combustion, and secondary combustion, the system achieves graded processing of BOG gas at different pressure levels, ensuring stable combustion from low pressure to high pressure. An auxiliary gas pipeline system supplements low-concentration natural gas with combustible gas, ensuring complete combustion of low-concentration natural gas. Venting branches and normally open venting valves ensure that gas can be safely discharged when the system is not running or under low pressure, preventing gas accumulation in the pipeline. The complex system is clearly divided into four major modules: natural gas pipeline, auxiliary fuel, combustion air, and GCU combustion unit, with clear connections and functional divisions for each module.

[0013] Preferably, the main natural gas pipeline is further provided with an emergency venting branch pipeline, which is connected in parallel with the emergency venting branch pipeline, and the emergency venting branch pipeline is provided with a normally closed venting valve.

[0014] By adopting the above technical solution, when the pressure exceeds the system's normal handling capacity (e.g., ≥500kPa), the normally closed vent valve opens in an emergency to directly release the high-pressure gas, preventing damage or explosion to upstream pipelines and equipment due to overpressure. This, together with the aforementioned normally open vent valve, forms a dual venting protection system that complements both "normal" and "emergency" protection.

[0015] Preferably, it also includes a nitrogen pipeline system, which includes a nitrogen pipeline and a third control valve group for controlling the on / off state of the nitrogen pipeline. The nitrogen pipeline is connected in series with an ignition branch pipeline, a first combustion branch pipeline and a second combustion branch pipeline, and is connected in parallel with a natural gas main pipeline and an auxiliary gas pipeline.

[0016] By adopting the above technical solution, inert nitrogen is injected into each gas pipeline through the nitrogen pipeline before the system is started or after it is shut down, so as to replace the residual air or combustible gas, keep the internal environment of the system in a safe state, and prevent combustible gas from forming an explosive mixture with air.

[0017] Preferably, it also includes a heating air duct system, which includes a heating fan, a heating air duct connected to the heating fan, and a heater disposed on the heating air duct. The end of the heating air duct away from the heating fan is connected to the processing chamber.

[0018] By adopting the above technical solution, the air delivered by the heating fan is heated by a heater, and then the hot air is sent into the treatment chamber to continuously keep the bottom of the burner warm, preventing low-temperature gas and condensate from freezing at the burner nozzle. This solves the technical problem that low-temperature BOG may cause the burner nozzle to freeze and become blocked, and improves the reliability of the system in low-temperature environments.

[0019] Preferably, the auxiliary gas pipeline has an auxiliary venting branch, and the auxiliary venting branch is equipped with a normally open venting valve II.

[0020] By adopting the above technical solution, an independent safe venting channel is provided for the auxiliary fuel pipeline, preventing the pipeline from experiencing abnormal pressure increases due to heat or other reasons when in standby mode.

[0021] Preferably, a flame detection device is provided on the side wall of the processing chamber.

[0022] By adopting the above technical solution, the combustion status is monitored in real time. Once flameout is detected, an alarm is immediately sent to the control system and the gas supply is cut off to prevent unburned gas from accumulating and causing deflagration.

[0023] Preferably, a temperature detection device is provided on the side wall of the processing chamber.

[0024] By adopting the above technical solution, the temperature inside the incineration device is monitored, which serves as both a basis for interlocking and controlling the combustion air volume and a basis for determining whether to start the heating air pipeline system.

[0025] Secondly, the control method for a marine BOG gas combustion device provided in this application adopts the following technical solution:

[0026] A control method based on the above-mentioned marine BOG gas combustion equipment.

[0027] When the pressure monitoring device detects that the natural gas pressure on the main natural gas pipeline is ≥5 kPa, the normally open distribution valve is closed, the ignition branch pipeline is opened, the combustion fan is turned on, and the ignition module of the burner is ignited to form a permanent flame; when the pressure monitoring device detects that the natural gas pressure on the main natural gas pipeline is ≥10 kPa, the first combustion branch pipeline is opened, and the main combustion module of the burner starts to burn; when the pressure monitoring device detects that the natural gas pressure on the main natural gas pipeline is ≥80 kPa, the second combustion branch pipeline is opened, and the main combustion module of the burner continues to burn.

[0028] When the gas concentration detection device detects that the natural gas concentration in the main natural gas pipeline is less than 15%, the auxiliary gas pipeline is opened.

[0029] By adopting the above technical solutions, pressure-based staged ignition control, using pressure as the decision variable, enables automatic and stable system startup and load regulation; concentration-based calorific value compensation control, using concentration as the decision variable, solves the industry problem of unstable combustion of low-calorific-value gases; and automatic addition of high-calorific-value auxiliary fuel ensures stable combustion flame and complete destruction of methane.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. This solution successfully addresses the challenges of drastic fluctuations in BOG gas pressure, temperature, and composition through two core mechanisms: "pressure-based staged combustion" and "concentration-based calorific value compensation." The system can automatically activate ignition, primary combustion, and secondary combustion pipelines based on gas pressure, covering a wide range from slightly positive pressure to ultra-high pressure. Simultaneously, when low methane concentration is detected, auxiliary fuel is automatically added to ensure stable combustion of low-calorific-value gases, thus achieving seamless "one-stop" processing of BOG from three sources on board ships.

[0032] 2. This solution employs a multi-layered safety design to construct a defense-in-depth system. Dual shut-off valves and intermediate chamber pressure monitoring are installed on key pipelines to effectively prevent leakage risks; three-level venting paths for conventional, emergency, and auxiliary fuel systems provide precise pressure relief for different operating conditions; in addition, nitrogen purging function and redundant configuration of key sensors jointly ensure that the system operates safely without overpressure, leakage, or deflagration in complex and harsh marine environments.

[0033] 3. This solution is specifically designed for the low-temperature and high-humidity environment at sea. An independent heating air system automatically prevents burner nozzles from icing and clogging, ensuring the system is always available. Simultaneously, intelligent interlocking regulation of combustion air volume and flue gas temperature guarantees efficient and stable combustion under various loads. This enables the system to maintain an extremely high start-up success rate and continuous operation capability even in harsh marine environments. Attached Figure Description

[0034] Figure 1 This is a simplified structural diagram of the marine BOG gas combustion device according to Embodiment 1 of this application.

[0035] Explanation of reference numerals in the attached diagram: 1. Main natural gas pipeline; 11. Gas concentration detection device; 12. Pressure monitoring device; 13. Manual switching valve one; 14. Automatic shut-off valve one; 15. Automatic shut-off valve two; 16. Flow meter; 17. Temperature detection element one; 18. Pressure detection element one; 2. Ignition branch pipeline; 21. Flow regulating valve one; 31. First combustion branch pipeline; 32. Second combustion branch pipeline; 33. Automatic shut-off valve three; 34. Automatic flow regulating valve one; 35. Automatic shut-off valve four; 36. Automatic flow regulating valve two; 37. Pressure detection element three; 41. Venting branch pipeline; 411. Normally open venting valve one; 412. Manual switching valve two; 42. Emergency venting branch pipeline; 421. Normally closed venting valve; 422. Manual switching valve three; 5. Auxiliary Combustion-supporting gas pipeline; 51. Auxiliary venting branch; 511. Normally open venting valve II; 512. Manual switching valve VI; 52. Manual switching valve IV; 53. Automatic shut-off valve V; 54. Automatic shut-off valve VI; 55. Manual switching valve V; 6. Heating air pipeline; 61. Heating fan; 62. Heater; 63. Automatic switching valve VIII; 64. Pressure detection element II; 65. Temperature detection element II; 7. Combustion-supporting air pipeline; 71. Combustion fan; 72. Flow regulating valve II; 81. Air distribution chamber; 82. Processing chamber; 83. Combustion chamber; 84. Burner; 85. Flame detection device; 86. Temperature detection device; 87. Pressure monitoring element; 88. Observation hole; 9. Nitrogen pipeline; 91. Manual shut-off valve VII; 92. Automatic shut-off valve VII; 93. Check valve. Detailed Implementation

[0036] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0037] The directional terms such as "up," "down," "left," "right," "front," and "back" used in this application only represent relative positions in the diagram and are used for the convenience of describing this application. They do not represent the absolute position of the product and should not be regarded as limitations on this application.

[0038] Example 1

[0039] This application discloses a marine BOG gas combustion device.

[0040] like Figure 1 As shown, the marine BOG gas combustion equipment of this embodiment includes a natural gas pipeline system, an auxiliary fuel gas pipeline system, a combustion air pipeline system, and a GCU combustion device. The natural gas pipeline system is connected to the natural gas to be discharged and treated on the transport ship. The GCU combustion device is used to incinerate the natural gas. The combustion air pipeline system provides air and oxygen to the GCU combustion device. The auxiliary fuel gas pipeline system supplements the combustion gas when the natural gas content is insufficient to ensure complete combustion.

[0041] The natural gas pipeline system includes a main natural gas pipeline 1, an ignition branch pipeline 2, a first combustion branch pipeline 31, and a second combustion branch pipeline 32. Ignition branch pipeline 2, first combustion branch pipeline 31, and second combustion branch pipeline 32 are connected in parallel and in series with the main natural gas pipeline 1. The main natural gas pipeline 1 is equipped with a gas concentration detection device 11, a pressure monitoring device 12, and a first control valve group for controlling the on / off state of the main natural gas pipeline 1. The first control valve group mainly includes a manual switching valve 13, an automatic shut-off valve 14, and an automatic shut-off valve 15. The main natural gas pipeline 1 is also equipped with a flow meter 16, a temperature detection element 17, and a pressure detection element 18. The flow meter 16, gas concentration detection device 11, manual switching valve 13, pressure monitoring device 12, temperature detection element 17, automatic shut-off valve 14, pressure detection element 18, and automatic shut-off valve 15 are arranged sequentially along the gas inlet direction. Automatic shut-off valve 14 and automatic shut-off valve 2 15 form a double shut-off valve group to ensure the safety performance of the natural gas main pipeline 1. Pressure detection element 18 is set in the middle of the double shut-off valve group to detect the sealing performance of the double shut-off valve group. Flow meter 16 is used to detect the natural gas flow rate. Gas concentration detection device is used to detect the natural gas ratio in the natural gas. When the natural gas ratio is <15%, auxiliary fuel is required to increase the calorific value of the gas.

[0042] The main natural gas pipeline 1 is equipped with a vent branch pipeline 41, which includes a normally open vent valve 411 and a manually operated switching valve 412. The vent branch pipeline 41 is located between a pressure detection element 18 and an automatic shut-off valve 15. When the pressure monitoring device 12 detects an incoming gas pressure < 5 kPa (this pressure threshold can be set according to actual needs), this pressure is too low, and the incoming gas volume is insufficient for combustion. The natural gas is then released to a safe high-altitude area for discharge through the normally open vent valve 411 and the vent branch pipeline 41. Furthermore, the main natural gas pipeline 1 also includes an emergency vent branch pipeline 42, which is connected in parallel with the vent branch pipeline 41. The emergency vent branch pipeline 42 is equipped with a normally closed vent valve 421 and a manually operated switching valve 422. The emergency vent branch pipeline 42 is located between a temperature detection element 17 and an automatic shut-off valve 14. When the pressure monitoring device 12 detects that the incoming gas pressure is ≥500 kPa, in order to prevent the natural gas from exploding due to excessive pressure, the natural gas is released to a safe high-altitude area by opening the normally closed vent valve 421 and the emergency vent branch line 42. The outlets of the emergency vent branch line 42 and the vent branch line 41 are combined into one pipeline for high-altitude discharge to the safe area.

[0043] The pipeline switching valves on ignition branch line 2 include flow regulating valve 21, which supplies ignition gas and the gas required for the burner 84. The pipeline switching valves on the first combustion branch line 31 include automatic shut-off valve 33 and automatic flow regulating valve 34, which control the on / off state and flow regulation of the first combustion branch line 31. The pipeline switching valves on the second combustion branch line 32 include automatic shut-off valve 35 and automatic flow regulating valve 36, which control the on / off state and flow regulation of the second combustion branch line 32. Natural gas from the main natural gas pipeline 1 can directly enter ignition branch line 2, while entering the first combustion branch line 31 or the second combustion branch line 32 requires the opening of corresponding shut-off valves and flow valves. Assuming the threshold range of automatic flow regulating valve 34 is 50–500 Nm³ / h and the threshold range of automatic flow regulating valve 36 is 300–3000 Nm³ / h, then the total flow rate of the first combustion branch 31 or the second combustion branch 32 is 50–3000 Nm³ / h, thus expanding the flow range and enabling it to handle various high-pressure and low-pressure natural gas without being unable to adapt to excessive changes in natural gas pressure.

[0044] The GCU incineration unit includes an air distribution chamber 81, a processing chamber 82, a combustion chamber 83, and a burner 84. The processing chamber 82 is located above the air distribution chamber 81 and the two are interconnected. The combustion chamber 83 is located within the processing chamber 82 and is interconnected with it. The burner 84 is located within the combustion chamber 83. The ignition module of the burner 84 is connected to an ignition branch line 2, which supplies natural gas to the ignition module of the burner 84 for ignition. The main combustion modules of the burner 84 are connected to a first combustion branch line 31 and a second combustion branch line 32, which supply natural gas to the main combustion modules of the burner 84 for combustion.

[0045] The combustion air duct system includes a combustion air fan 71 and a combustion air duct 7. One end of the combustion air duct 7 is connected to the combustion air fan 71, and the other end is connected to the air distribution chamber 81. It is used to deliver combustion air into the air distribution chamber 81 to provide oxygen for combustion in the combustion chamber 83. A flow regulating valve 72 is installed on the combustion air duct 7. The amount of combustion air can be adjusted according to the combustion conditions in the combustion chamber 83. The amount of combustion air is controlled individually or simultaneously by the flow regulating valve 72 and the combustion air fan 71. The combustion air fan 71 can be a variable frequency fan or a fixed frequency fan, typically operating in a one-on-one, two-on-one, or three-on-one-one-backup configuration.

[0046] It should be noted that in this embodiment, the outlets of the first combustion branch pipe 31 and the second combustion branch pipe 32 are merged into a single pipe, and a pressure detection element 37 is installed on the merged pipe. In other embodiments, the first combustion branch pipe 31 and the second combustion branch pipe 32 can also be separated and individually connected to different combustion nozzles on the burner 84. In this way, the first combustion branch pipe 31 and the second combustion branch pipe 32 can be controlled independently, such as opening the first combustion branch pipe 31 or the second combustion branch pipe 32 independently.

[0047] The auxiliary gas pipeline system includes an auxiliary gas pipeline 5 and a second control valve group. The second control valve group is used to control the on / off state of the auxiliary gas pipeline 5. The auxiliary gas pipeline 5 is connected in parallel with the main natural gas pipeline 1, and is connected in series with the ignition branch pipeline 2, the first combustion branch pipeline 31, and the second combustion branch pipeline 32, respectively, providing combustion-supporting gas to these three branch pipelines. The second control valve group mainly includes a manual switching valve 52, an automatic shut-off valve 53, an automatic shut-off valve 54, and a manual switching valve 55, arranged sequentially. The automatic shut-off valves 53 and 54 form a double shut-off valve system to ensure the safety performance of the auxiliary gas pipeline. When the gas concentration detection device 11 detects that the natural gas content in the natural gas is <15%, the automatic shut-off valves 53 and 54 are opened to introduce auxiliary fuel, ensuring the stable combustion performance of natural gas. The auxiliary fuel can be high-calorific-value gases such as natural gas, propane, and liquefied petroleum gas. It should be noted that the auxiliary gas pipeline 5 is also equipped with an auxiliary venting branch 51, which includes a normally open venting valve 2 511 and a manually operated switching valve 6 512. The auxiliary venting branch 51 is located between the automatic shut-off valve 53 and the automatic shut-off valve 6 54. When the auxiliary gas pipeline system is not activated, the auxiliary venting branch 51 is in the connected state to ensure the safe release of gas in the pipeline.

[0048] In this embodiment, the incineration equipment also includes a nitrogen pipeline system, which includes a nitrogen pipeline 9 and a third control valve group. The third control valve group is used to control the on / off state of the nitrogen pipeline 9. The nitrogen pipeline 9 is connected in series with the ignition branch pipeline 2, the first combustion branch pipeline 31, and the second combustion branch pipeline 32, and is connected in parallel with the main natural gas pipeline 1 and the auxiliary gas pipeline 5. The third control valve includes a manual shut-off valve 91, an automatic shut-off valve 92, and a check valve 93. Opening the manual shut-off valve 91 and the automatic shut-off valve 92 can supply nitrogen to the ignition branch pipeline 2, the first combustion branch pipeline 31, and the second combustion branch pipeline 32. The purpose is to purge the ignition branch line 2, the first combustion branch line 31, and the second combustion branch line 32 with inert nitrogen after the combustion system has finished burning and shut down. This purges any residual natural gas or combustible gas in the ignition and combustion lines into the combustion chamber 83, preventing the residual combustible gas in the pipelines from mixing with air to form an explosive mixture. Filling the pipelines with nitrogen prevents air from entering and forming an explosive mixture, thus eliminating the possibility of an explosion. In addition, it also prevents pipeline corrosion and ensures that the system is always in a safe start-up state. The check valve 93 only allows nitrogen to flow from upstream to the ignition and combustion lines, blocking any reverse flow of media from the gas pipeline to the nitrogen pipeline. This ensures that only pure and reliable inert nitrogen is injected during each purging operation, thereby ensuring that the purging process truly achieves a safe effect.

[0049] In this embodiment, the incineration equipment also includes a heating air duct system, which includes a heating air duct 6, a heating fan 61, and a heater 62. One end of the heating air duct 6 is connected to the heating fan 61, and the other end is connected to the processing chamber 82. The heater 62 is installed on the heating air duct 6. The heating air duct 6 is also equipped with an automatic switching valve 63, a pressure detection element 64, and a temperature detection element 65. The heating air duct 6 is used to deliver hot air into the processing chamber 82 and can directly enter the bottom of the burner 84 to prevent the burner 84 nozzles from freezing and clogging when the equipment is not running. The temperature detection element 65 is used to detect the temperature of the air coming from the heating air duct 6, ensuring that the heated air enters the processing chamber at a suitable temperature.

[0050] In this embodiment, the air distribution chamber 81 of the GCU incineration device mainly functions to uniformly distribute airflow. The heated air delivered by the heating air pipeline system enters the air distribution chamber 81, enters the processing chamber 82 through the air distribution hole at the top of the air distribution chamber 81, and then enters the combustion chamber 83 from the processing chamber 82 to provide oxygen for the burner 84. The processing chamber 82 is set at the upper part of the air distribution chamber 81. The processing chamber 82 and the combustion chamber 83 are arranged coaxially. The flow ratio of the combustion air and the temperature regulating air is freely distributed by the flow area of ​​the processing chamber 82 and the combustion chamber 83. The burner 84 is installed coaxially inside the combustion chamber 83. The ignition module (igniter) is installed near the ignition nozzle of the burner 84. The ignition module can be an ignition electrode or a high-energy igniter. The burner 84 is equipped with an independent gas nozzle corresponding to the ignition pipeline. The burner 84 is equipped with the same gas nozzle corresponding to the first combustion branch pipeline and the second combustion branch pipeline (or each can be equipped with an independent nozzle) to ensure stable combustion performance.

[0051] The side wall of the processing chamber 82 is equipped with a flame detection device 85, a temperature detection device 86, a pressure monitoring element 87, and a viewing hole 88. The flame detection device 85 automatically detects the combustion status of the burner 84. The temperature detection device 86 detects the temperature inside the processing chamber 82. The temperature detection device 86 is interlocked with the heating air duct system. When the temperature detection device 86 detects that the temperature inside the processing chamber 82 is <5℃, it opens the automatic switching valve 63, the heating fan 61, and the heater 62 on the heating air duct 6, supplying hot air into the processing chamber 82. The temperature detection device 86 is also interlocked with the combustion air duct system. When the temperature detection device 86 detects that the flue gas temperature inside the processing chamber 82 is >400℃, it increases the combustion air volume; when the temperature detection device 86 detects that the flue gas temperature inside the processing chamber 82 is <200℃, it reduces the combustion air volume, thereby reasonably and fully controlling the gas combustion in the combustion chamber 83. The viewing hole 88 is mainly used for manual detection of the flame status of the burner 84.

[0052] It should be noted that all the manual shut-off valves involved in this embodiment are equipped with valve position feedback function so as to accurately determine the position of each valve; all pressure monitoring devices (or pressure detection elements), temperature detection devices (or temperature detection elements), flame detection devices, etc. are designed with redundancy to provide double insurance for system safety.

[0053] The implementation principle of the marine BOG gas combustion equipment in this embodiment is as follows:

[0054] When the pressure monitoring device 12 detects that the incoming gas pressure on the natural gas main pipeline 1 is <5KPa, the automatic shut-off valve 14 and the automatic shut-off valve 25 are closed, and the natural gas is directly discharged at high altitude through the venting branch pipeline 41 and the normally open venting valve 411.

[0055] When the pressure monitoring device 12 detects that the incoming natural gas pressure is ≥5KPa, it closes the normally open venting valve 411 to close the venting branch pipe 41, opens the automatic shut-off valve 14 and the automatic shut-off valve 25, opens the ignition branch pipe 2 to allow natural gas to enter the ignition module of the burner 84, and turns on the combustion fan 71 to ignite the ignition module of the burner 84 to form a permanent flame.

[0056] When the pressure monitoring device 12 detects that the incoming natural gas pressure is ≥10KPa, the automatic shut-off valve 33 is opened to connect the first combustion branch pipeline 31, and the main combustion module of the burner 84 starts combustion.

[0057] When the pressure monitoring device 12 detects that the incoming natural gas pressure N≥80KPa, it opens the automatic shut-off valve 35 to connect the second combustion branch pipeline 32, and the main combustion module of the burner 84 continues to burn.

[0058] When the pressure monitoring device 12 detects that the incoming natural gas pressure is ≥500KPa, the normally closed vent valve 421 is opened to open the emergency vent branch pipeline 42, and the natural gas is released to the high-altitude safe area in an emergency.

[0059] Specifically, when the temperature detection device 86 of the processing chamber 82 detects that the flue gas temperature in the processing chamber 82 is >400℃, the combustion air volume is increased; when the temperature detection device 86 detects that the flue gas temperature in the processing chamber 82 is <200℃, the combustion air volume is reduced.

[0060] When the gas concentration detection device 11 detects that the natural gas concentration on the main natural gas pipeline 1 is less than 15%, it opens the auxiliary gas pipeline 5 to supplement combustion gas to the ignition branch pipeline 2, the first combustion branch pipeline 31, and the second combustion branch pipeline 32, so that the low-concentration natural gas can be fully combusted.

[0061] After the natural gas combustion is completed and the equipment is shut down, the nitrogen pipeline system is turned on, and the ignition branch line 2, the first combustion branch line 31 and the second combustion branch line 32 are purged with inert nitrogen to ensure that the equipment is always in a state where it can be safely started.

[0062] When the incineration equipment is in a low-temperature environment and is not executing the natural gas combustion procedure, the temperature is detected by the temperature detection device 86 of the processing chamber 82. When the temperature detection device 86 detects that the temperature inside the processing chamber 82 is <5℃, the heating fan 61 and heater 62 are turned on to deliver hot gas into the processing chamber 82 to prevent the nozzles of the main combustion module of the burner 84 from freezing and becoming blocked at low temperatures when the equipment is not running.

[0063] Example 2

[0064] This application discloses a control method for a marine BOG gas combustion equipment, which specifically includes the following steps:

[0065] When the pressure monitoring device 12 detects that the natural gas pressure on the main natural gas pipeline 1 is ≥5 kPa, it closes the normally open vent valve 411, opens the ignition branch pipeline 2, turns on the combustion fan 71, and the ignition module of the burner 84 ignites, forming a permanent flame; when the pressure monitoring device 12 detects that the natural gas pressure on the main natural gas pipeline 1 is ≥10 kPa, it opens the first combustion branch pipeline 31, and the main combustion module of the burner 84 starts combustion; when the pressure monitoring device 12 detects that the natural gas pressure on the main natural gas pipeline 1 is ≥80 kPa, it opens the second combustion branch pipeline 32, and the main combustion module of the burner 84 continues to burn.

[0066] When the gas concentration detection device 11 detects that the natural gas concentration on the main natural gas pipeline 1 is less than 15%, the auxiliary gas pipeline 5 is opened.

[0067] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A marine BOG gas incineration apparatus, characterized by: The system comprises a natural gas pipeline system, an auxiliary gas pipeline system, a combustion air pipeline system and a GCU burning device. The natural gas pipeline system comprises a natural gas main pipeline (1), an ignition branch pipeline (2), a first combustion branch pipeline (31) and a second combustion branch pipeline (32) connected in series with the natural gas main pipeline (1), wherein the ignition branch pipeline (2), the first combustion branch pipeline (31) and the second combustion branch pipeline (32) are connected in parallel, the natural gas main pipeline (1) is provided with a gas concentration detection device (11), a pressure monitoring device (12) and a first control valve group for controlling the on-off of the natural gas main pipeline (1), the natural gas main pipeline (1) is provided with a diffusion branch pipeline (41), the diffusion branch pipeline (41) is provided with a normally open diffusion valve (411), and the ignition branch pipeline (2), the first combustion branch pipeline (31) and the second combustion branch pipeline (32) are respectively provided with pipeline on-off valves. The auxiliary gas pipeline system comprises an auxiliary gas pipeline (5) and a second control valve group for controlling the on-off of the auxiliary gas pipeline (5), wherein the auxiliary gas pipeline (5) is connected in parallel with the natural gas main pipeline (1) and connected in series with the ignition branch pipeline (2), the first combustion branch pipeline (31) and the second combustion branch pipeline (32). The combustion air pipeline system comprises a combustion air fan (71) and a combustion air pipeline (7) connected with the combustion air fan (71). The GCU burning device comprises a wind distribution chamber (81), a treatment chamber (82), a combustion chamber (83) and a burner (84), wherein the treatment chamber (82) is arranged above the wind distribution chamber (81) and the two are connected with each other, the combustion chamber (83) is arranged in the treatment chamber (82) and the two are connected with each other, the burner (84) is arranged in the combustion chamber (83), the ignition branch pipeline (2) is connected with an ignition module of the burner (84), the first combustion branch pipeline (31) and the second combustion branch pipeline (32) are respectively connected with main combustion modules of the burner (84), and the combustion air pipeline (7) is connected with the wind distribution chamber (81); the natural gas main pipeline (1) is further provided with an emergency diffusion branch pipeline (42), the diffusion branch pipeline (41) and the emergency diffusion branch pipeline (42) are connected in parallel, and the emergency diffusion branch pipeline (42) is provided with a normally closed diffusion valve (421).

2. Marine BOG gas burning plant according to claim 1, characterized in that: The system further comprises a nitrogen pipeline system, wherein the nitrogen pipeline system comprises a nitrogen pipeline (9) and a third control valve group for controlling the on-off of the nitrogen pipeline (9), the nitrogen pipeline (9) is connected in series with the ignition branch pipeline (2), the first combustion branch pipeline (31) and the second combustion branch pipeline (32), and the nitrogen pipeline is connected in parallel with the natural gas main pipeline (1) and the auxiliary gas pipeline (5).

3. Marine BOG gas burning apparatus according to claim 1, characterized in that: The system further comprises a heating air pipeline system, wherein the heating air pipeline system comprises a heating air fan (61), a heating air pipeline (6) connected with the heating air fan (61) and a heater (62) arranged on the heating air pipeline (6), and the heating air pipeline (6) is connected with the treatment chamber (82) at an end away from the heating air fan (61).

4. Marine BOG gas burning plant according to any one of claims 1 to 3, characterized in that: The auxiliary gas pipeline (5) has an auxiliary diffusion branch (51), and the auxiliary diffusion branch (51) is provided with a normally-open diffusion valve two (511).

5. Marine BOG gas burning apparatus according to any one of claims 1 to 3, characterized in that: The processing chamber (82) is provided with a flame detection device (85) on the side wall.

6. Marine BOG gas burning apparatus according to any one of claims 1 to 3, characterized in that: The processing chamber (82) is provided with a temperature detection device (86) on the side wall.

7. A control method for the ship BOG gas burning equipment according to any one of claims 1 to 6, characterized in that: When the pressure monitoring device (12) detects that the natural gas pressure on the natural gas main pipeline (1) is greater than or equal to 5KPa, the normally-open diffusion valve (411) is closed, the ignition branch pipeline (2) is opened, the combustion air fan (71) is started, the ignition module of the burner (84) is ignited to form a long-lasting fire; when the pressure monitoring device (12) detects that the natural gas pressure on the natural gas main pipeline (1) is greater than or equal to 10KPa, the first combustion branch pipeline (31) is opened, and the main combustion module of the burner (84) is started to burn; when the pressure monitoring device (12) detects that the natural gas pressure on the natural gas main pipeline (1) is greater than or equal to 80KPa, the second combustion branch pipeline (32) is opened, and the main combustion module of the burner (84) continues to burn; When the gas concentration detection device (11) detects that the natural gas concentration on the natural gas main pipeline (1) is less than 15%, the auxiliary gas pipeline (5) is started.

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