A flare system and method of staged combustion

Abstract

The application discloses a kind of torch systems and fractional combustion method of fractional combustion, belong to petroleum chemical industry technical field, the torch system includes multiple stage torch and multiple fractional tanks, fractional tank has first water inlet, gas input pipeline and gas outlet, gas input pipeline extends from the outer wall of fractional tank towards the liquid level direction of water seal medium, when fractional tank inputs water seal medium, the outlet of gas input pipeline is located inside water seal medium, water seal medium has water seal pressure greater than the discharge pressure of combustible gas, to prevent combustible gas from breaking through water seal medium and discharging into corresponding torch.The whole process can control the launch of corresponding stage number of torch according to the pressure of combustible gas, and the water seal pressure of water seal medium in fractional tank is used to realize fractional control, so that the specification of fractional channel is not limited, and the emission of combustible gas fractional combustion is not limited, the processing needs of large emission and small emission of combustible gas can be considered simultaneously.

Description

Technical Field

[0001] This application relates to the field of petrochemical technology, specifically to a staged combustion flare system and a staged combustion method. Background Technology

[0002] Flare systems can be used to treat combustible gases emitted from petrochemical plants during start-up, shutdown, and accident conditions, converting the combustible gases into gases before releasing them into the atmosphere through combustion. In recent years, with the successive construction of large-scale integrated refining and chemical plants, the composition of combustible gases emitted by these plants has become increasingly complex, often containing extremely or highly toxic gases, and the emission volume has also become increasingly volatile.

[0003] Traditional flare systems mainly use pneumatic butterfly valves installed in the staged channels to achieve combustion of combustible gases with different emission volumes. However, the specifications of the pneumatic butterfly valves limit the specifications of the staged channels, thereby limiting the emission volume of combustible gases during staged combustion. Consequently, traditional flare systems cannot simultaneously meet the treatment needs of combustible gases with large and small emission volumes. Summary of the Invention

[0004] Purpose of the invention: The embodiments of this application provide a staged combustion flare system, which aims to overcome the technical problem in the prior art that it is impossible to simultaneously meet the treatment needs of combustible gases with large and small emissions; another purpose of the embodiments of this application is to provide a staged combustion method.

[0005] Technical solution: The staged combustion flare system described in this application includes:

[0006] Multiple grading tanks are arranged in parallel. Each grading tank has a first water inlet, a gas input pipe, and a gas outlet. The first water inlet is used to input a water seal medium. The gas input pipe extends from the outer wall of the grading tank toward the liquid surface of the water seal medium and is used to input a combustible gas to be burned.

[0007] A multi-stage flare arranged in parallel, each flare having an air inlet, and the air inlets of the multiple flares being connected one-to-one with the gas outlets of the multiple stage tanks;

[0008] When the water seal medium is introduced into the grading tank, the outlet of the gas input pipe is located inside the water seal medium. The water seal medium has a set water seal pressure, and the combustible gas to be burned has a discharge pressure. The set water seal pressure is greater than the discharge pressure to prevent the combustible gas to be burned from breaking through the water seal medium and being discharged into the corresponding flare through the gas outlet.

[0009] In some embodiments, a baffle is provided inside the grading tank. One side of the baffle forms a water-sealed area by enclosing a portion of the inner wall of the grading tank, and the other side of the baffle forms a non-water-sealed area by enclosing a portion of the inner wall of the grading tank.

[0010] The grading tank also has an outlet, the first inlet is distributed in the water seal area, and the outlet is distributed in the non-water seal area. The difference between the liquid level of the water seal medium in the water seal area and the liquid level of the water seal medium in the non-water seal area is configured as the water seal height that generates the water seal pressure.

[0011] In some embodiments, the water-sealed area and the non-water-sealed area are connected by a drain valve, which is used to divert the water-sealed medium in the water-sealed area to the non-water-sealed area.

[0012] The non-water-sealed area is also equipped with an overflow pipe, which is used to maintain the liquid level of the water-sealed medium in the non-water-sealed area at a preset height.

[0013] In some embodiments, the grading tank is further provided with a liquid level detection device, which is connected to the controller and is used to detect the height of the first water seal.

[0014] In some embodiments, the water seal height is set differently for each of the grading tanks.

[0015] In some embodiments, the grading tank is further provided with a liquid level detection device, which is used to detect the liquid level height of the water-sealed medium in the water-sealed area and / or to detect the liquid level height of the water-sealed medium in the non-water-sealed area.

[0016] In some embodiments, the first water inlet is connected to an industrial water source via a first water supply valve;

[0017] The grading tank also has a second water inlet distributed in the water seal area. The second water inlet is connected to the water outlet of the water storage tank through a second water replenishment valve. The water storage tank is positioned higher than the liquid level of the water seal medium in the water seal area.

[0018] In some embodiments, the staged combustion flare system further includes:

[0019] The distribution pipe has multiple gas outlets, which are connected one-to-one with the inlets of the gas input pipes of the multiple staged tanks. The distribution pipe is used to buffer the combustible gas to be burned and to divide the combustible gas to be burned into multiple paths through the multiple gas outlets.

[0020] In some embodiments, at least one pressure detection device is provided on the distribution pipe, the pressure detection device being used to detect the pressure of the combustible gas to be burned.

[0021] In some embodiments, the staged combustion flare system further includes:

[0022] The liquid separator is connected to the distribution pipe and is used to separate the liquid phase from the combustible gas to be burned.

[0023] In some embodiments, the staged combustion flare system further includes:

[0024] Multiple water seal tanks are provided, each corresponding to one of the multiple stages of the flare. The water seal tanks are connected between the air inlet of the corresponding flare and the gas outlet of the corresponding stage tank. The water seal tanks are used to perform flame arresting treatment on the corresponding flares.

[0025] In some embodiments, the air inlet of each stage of the torch is connected to an inert gas source through a corresponding inert gas purging valve. The inert gas purging valve is used to open when the torch is shut down, so that inert gas can enter the torch for purging protection.

[0026] In some embodiments, the multiple torches are all elevated torches.

[0027] In some embodiments, the staged combustion flare system further includes:

[0028] A controller is used to control the liquid level of the water seal medium in the grading tank, so that the water seal medium generates a set water seal pressure in the grading tank.

[0029] Accordingly, the staged combustion method of a flare system employing staged combustion as described in any of the above embodiments, as described in the embodiments of this application, includes:

[0030] Based on the pressure range of the combustible gas to be burned, the controller determines the target stage tank to be put into use from the stage tanks that are arranged in parallel with the multi-stage flares.

[0031] The controller controls the water seal medium in the target grading tank to decrease until the outlet of the gas input pipe of the target grading tank is exposed, so that the combustible gas to be burned output from the outlet of the gas input pipe is input into the gas inlet of the corresponding torch of the target grading tank for combustion through the gas outlet of the target grading tank.

[0032] In some embodiments, the controller determines the target stage tank to be put into use from each of the parallel stage tanks corresponding to the multi-stage flares, based on the pressure range of the combustible gas to be burned, including:

[0033] The controller compares the pressure of the combustible gas to be burned with the preset pressure threshold corresponding to each stage tank of the multi-stage flare.

[0034] The controller identifies grading tanks with a preset pressure threshold lower than the pressure of the combustible gas to be burned as target grading tanks to be put into use.

[0035] Beneficial Effects: Compared with the prior art, the staged combustion flare system of this application includes multiple flares and multiple staged tanks connected to the air inlets of the multiple flares. Each staged tank has a first water inlet, a gas input pipe, and a gas outlet. The first water inlet is used to input a water seal medium. The gas input pipe extends from the outer wall of the staged tank toward the liquid surface of the water seal medium and is used to input the combustible gas to be burned. When the water seal medium is input into the staged tank, the outlet of the gas input pipe is located inside the water seal medium. The water seal medium has a set water seal pressure, and the combustible gas to be burned has an emission pressure. The set water seal pressure is greater than the emission pressure to prevent the combustible gas to be burned from breaking through the water seal medium and being discharged into the corresponding flare through the gas outlet. The entire process can control the deployment of the corresponding number of flares according to the pressure of the combustible gas to be burned, and use the water seal pressure of the water seal medium in the staged tank to achieve staged control. This makes the specifications of the staged channels unrestricted, and thus does not limit the emission volume of the combustible gas staged combustion, and can simultaneously meet the processing needs of combustible gases with large and small emission volumes.

[0036] Compared with existing technologies, the staged combustion method of this application includes: a controller, based on the pressure range of the combustible gas to be burned, determines the target staged tank to be used from among the staged tanks corresponding to the multi-stage parallel-arranged flares; then, the controller controls the liquid level of the water seal medium in the target staged tank to decrease until the outlet of the gas input pipe of the target staged tank is exposed, so that the combustible gas to be burned output from the outlet of the gas input pipe passes through the gas outlet of the target staged tank and enters the gas inlet of the corresponding flare for combustion. The entire process can control the deployment of the corresponding staged flares according to the pressure of the combustible gas to be burned, and utilizes the water seal pressure of the water seal medium in the staged tank to achieve staged control, thereby making the specifications of the staged channels unrestricted, and thus not limiting the emission volume of the combustible gas staged combustion, simultaneously accommodating the treatment needs of both large and small emission volumes of combustible gases. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the specific structure of the staged combustion flare system according to an embodiment of this application;

[0039] Figure 2 yes Figure 1 A magnified structural diagram of A in the diagram.

[0040] Figure label:

[0041] 01-Industrial water source; 02-Combustible gas source; 03-Inert gas source; 10-Flame; 11-Inert gas purge valve; 101-Air inlet; 20-Grading tank; 201-First water inlet; 202-Gas input pipeline; 203-Gas outlet; 204-Water outlet; 205-Second water inlet; 21-Baffle; 22-Water drain valve; 23-Liquid level detection device; 24-First water replenishment valve; 25-Second water replenishment valve; 26-Water seal area; 27-Non-water seal area; 30-Controller; 40-Water storage tank; 41-Third water replenishment valve; 50-Distribution pipe; 501-Air outlet; 51-Pressure detection device; 60-Divider tank; 70-Water seal tank; 71-Fourth water replenishment valve. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0043] In the description of this application, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, and "at least one" can mean one, two, or more, unless otherwise explicitly specified.

[0044] The applicant noted that traditional elevated flare systems mainly use a single channel to process combustible gases. To ensure the safe operation of the device, they are usually designed according to the maximum emission capacity. This results in a low flow rate of combustible gas at the flare outlet when the flow rate is low, and insufficient kinetic energy. Consequently, the combustible gas has a weak ability to entrain surrounding air, leading to poor mixing of combustible gas and air, incomplete combustion, black smoke, and environmental pollution. Low-flow emissions are also prone to problems such as smoldering and backfire of combustible gas inside the flare head.

[0045] Traditional ground flare systems can address the combustion of combustible gases at different flow rates through staged combustion. Staged combustion is mainly achieved by installing pneumatic butterfly valves in the staged channels. However, the specifications of the staged channels in a ground flare are limited by the specifications of the pneumatic butterfly valves. The specifications of the staged channels usually cannot exceed DN700 (pipe diameter of 700 mm). Furthermore, ground flares are generally not allowed to handle toxic combustible gases with extremely or highly hazardous toxicity.

[0046] However, since the pipe diameter of the combustible gas emission system of large-scale integrated refining and chemical plants is usually greater than DN1000 (pipe diameter is 1000 mm), and the number of plants is large and the composition of the emission gas is complex, usually containing extremely or highly toxic emission gases, in order to solve the problem of safe and environmentally friendly combustion of toxic combustible gases emitted by large-scale integrated refining and chemical projects, an elevated flare system that can perform staged combustion according to the changes in the amount of combustible gas emitted is needed.

[0047] In view of this, embodiments of this application provide a compressor component system to solve at least part of the above-mentioned technical problems.

[0048] Please refer to the following: Figure 1 and Figure 2 , Figure 1 The illustration shows the specific structure of the staged combustion flare system according to an embodiment of this application. Figure 2 It indicated Figure 1 An enlarged structure of the staged combustion flare system. In this embodiment, the staged combustion flare system mainly includes multiple flares 10 arranged in parallel and multiple staged combustion tanks 20 arranged in parallel. Each staged combustion tank 20 has a first water inlet 201, a gas input pipe 202, and a gas outlet 203. The first water inlet 201 is used to input a water seal medium, such as industrial water. This provides better flame-retardant properties and is readily available, offering greater practicality. The gas input pipe 202 extends from the outer wall of the staged combustion tank 20 towards the liquid surface of the water seal medium. Exemplarily, the gas input pipe 202 can extend from the outer wall of the staged combustion tank 20 in a direction perpendicular to the liquid surface of the water seal medium. The gas input pipe 202 is used to input the combustible gas to be burned. Each flare 10 has an air inlet 101, and the air inlets 101 of the multiple flares 10 are connected one-to-one with the gas outlets 203 of the multiple staged combustion tanks 20.

[0049] When the water seal medium is introduced into the grading tank 20, the outlet of the gas inlet pipe 202 is located inside the water seal medium, that is, below the liquid surface of the water seal medium. The water seal medium has a set water seal pressure, and the combustible gas to be burned has a discharge pressure. The set water seal pressure is greater than the discharge pressure to prevent the combustible gas to be burned from breaking through the water seal medium and being discharged into the corresponding flare 10 through the gas outlet 203.

[0050] In some embodiments, the multi-stage flares 10 may all be elevated flares. Exemplarily, the elevated flares are positioned at the same height. This allows for better combustion treatment of toxic emissions. In other embodiments, the multi-stage flares 10 may also be ground flares.

[0051] By setting up the aforementioned elevated flares, combustible gases are burned in stages. Compared to the incomplete combustion and black smoke caused by the concentrated combustion of large-volume combustible gases, staged combustion can disperse the flames, make full use of the surrounding air during combustion, have a better smoke suppression effect, and reduce the flame height, which is beneficial to the safety of surrounding aviation.

[0052] It should be noted that, for ease of description, Figure 1 This example demonstrates how combustible gases can be divided into three stages for combustion treatment. In practical applications, two-stage, four-stage, or more stages can be set, and this embodiment does not impose any specific limitations on this.

[0053] In some embodiments, a baffle 21 may be provided inside the grading tank 20. One side of the baffle 21 may enclose a portion of the inner wall of the grading tank 20 to form a water-sealed region 26, and the other side of the baffle 21 may enclose a portion of the inner wall of the grading tank 20 to form a non-water-sealed region 27. In some embodiments, the space of the water-sealed region 26 is smaller than the space of the non-water-sealed region 27. For example, the space of the non-water-sealed region 27 may be 1.5 times the space of the water-sealed region 26. This ensures that when the water-sealed medium in the water-sealed region 26 is diverted to the non-water-sealed region 27, the non-water-sealed region 27 has sufficient accommodating space.

[0054] Specifically, the shape of the baffle 21 is adapted to the shape of the inner wall of the classifier tank 20. For example, if the cross-sectional shape of one angle of the inner wall of the classifier tank 20 is circular, then the baffle 21 can be semi-circular, and the semi-circular arc profile is fixedly connected to part of the inner wall of the classifier tank 20. The height of the baffle 21 is less than the height of the inner wall of the classifier tank 20, so that the spaces of the water seal area 26 and the non-water seal area 27 are connected. The height of the baffle 21 can determine the maximum liquid level of the water seal medium in the water seal area 26. In this way, when the water seal medium fills the entire water seal area 26, it will flow from the top of the baffle 21 to the non-water seal area 27, thereby making the maximum liquid level of the water seal medium in the water seal area 26 level with the height of the baffle 21. This allows for physical control of the liquid level without controlling the input amount of the water seal medium.

[0055] The grading tank 20 may also have an outlet 204, a first inlet 201 distributed in the water seal region 26, and an outlet 204 distributed in the non-water seal region 27. The difference between the liquid level of the water seal medium in the water seal region 26 (e.g., H1+H2) and the liquid level of the water seal medium in the non-water seal region 27 (e.g., H2), for example, H1, is configured as the water seal height that generates the water seal pressure.

[0056] In this embodiment of the application, the water seal pressure and water seal height generated by the water seal medium in the grading tank 20 can be related by the following formula (1):

[0057]

[0058] In formula (1), P is the water seal pressure, ρ is the density of the water seal medium, g is the gravitational acceleration, and h is the water seal height.

[0059] In some embodiments, the water-sealed area 26 and the non-water-sealed area 27 can be connected by a drain valve 22, which is used to divert the water-sealed medium in the water-sealed area 26 to the non-water-sealed area 27.

[0060] In some embodiments, the non-water-sealed area 27 is further provided with an overflow pipe, which is used to maintain the liquid level of the water-sealed medium in the non-water-sealed area 27 at a preset overflow height (e.g., H2). Thus, when the liquid level of the water-sealed medium in the non-water-sealed area 27 exceeds the preset overflow height, the overflow pipe can overflow the water-sealed medium into a low-level sewage tank (or sewage container). The overflow pipe can also seal the non-water-sealed area 27 to prevent it from communicating with the outside space. In some embodiments, the preset overflow height is greater than zero. Exemplarily, the preset overflow height is any one or a combination of 50mm, 100mm, 150mm, 200mm, 250mm, 300mm, 310mm, 320mm, 330mm, 340mm, 350mm, 360mm, 370mm, 380mm, 390mm, and 400mm.

[0061] By setting up the aforementioned grading tank 20, the baffle 21 divides the internal space of the grading tank 20 into a water-sealed area 26 and a non-water-sealed area 27. This allows the water-sealing medium to quickly establish a water seal in the water-sealed area 26. When the water seal needs to be removed, the water-sealing medium can be quickly introduced into the non-water-sealed area 27 within 2 minutes via the water-removal valve 22, thereby greatly improving the speed of water seal establishment and removal. In addition, the grading control is achieved by utilizing the water seal pressure of the water-sealing medium, thus making the specifications of the grading channel unrestricted and not limiting the emission volume of combustible gas during grading combustion. This allows for the simultaneous handling of both large and small emission volumes of combustible gas.

[0062] In other embodiments, the baffle 21 may not be provided inside the grading tank 20, so that the cavity formed by the entire inner wall of the grading tank 20 is used to carry the water seal medium. This application embodiment does not specifically limit this.

[0063] In some embodiments, the water seal heights set for each stage tank 20 can be different. For example, the water seal heights for generating water seal pressure in the n stage tanks 20 are set as H11, H12, ..., H1n, respectively, and H11, H12, ..., H1n increase sequentially from smallest to largest. Generally, the higher the water seal height, the greater the water seal pressure generated by the water seal medium. Thus, as the pressure of the combustible gas to be burned gradually increases, the water seal medium of the corresponding stage tank 20 is removed sequentially according to the water seal height from smallest to largest, thereby setting up staged combustion. This ensures that the combustible gas is fully combusted in stages from a small emission level to the designed emission level, and during staged combustion, it ensures that the pressure of the combustible gas will not exceed the water seal pressure generated by the water seal height of the next stage tank 20, thereby improving reliability.

[0064] In some embodiments, the commissioning sequence of the grading system and flare 10 can be switched by adjusting the set water seal height. For example, after the first-stage flare 10 has been in operation for one year, it can be switched between the first-stage and second-stage flares 10. Specifically, the water seal height of the first-stage grading tank 20 is increased from H11 to H12, and the water seal height of the second-stage grading tank 20 is decreased from H12 to H11, thus achieving the switching between the first and second stages. When it is necessary to switch the third stage back to the first stage, simply adjust H13 to H11 as described above. In this way, by adjusting the water seal height of each grading tank 20, multiple flares 10 can be switched between each other. Adjusting the commissioning sequence of the flares 10 in this way can extend the life of the flare system and better meet the requirements for mutual maintenance of the flares 10.

[0065] In other embodiments, the water seal height set for each stage tank 20 can also be set to the same value. For example, it can be set to the water seal pressure corresponding to the water seal pressure that is greater than the maximum discharge pressure of the combustible gas to be burned. This can accommodate various discharge variations of the combustible gas to be burned. This application does not specifically limit this aspect.

[0066] For example, taking the combustion treatment of combustible gas in three stages as an example, the water seal height H11 set in the first-stage grading tank 20 ranges from 0mm to 2000mm. In some embodiments, the water seal height H11 set in the first-stage grading tank 20 is any one or any two of the following values: 0mm, 100mm, 200mm, 300mm, 400mm, 500mm, 600mm, 700mm, 800mm, 900mm, 1000mm, 1100mm, 1200mm, 1300mm, 1400mm, 1500mm, 1600mm, 1700mm, 1800mm, 1900mm, and 2000mm. The water seal height H12 set in the second-stage grading tank 20 ranges from 750mm to 2500mm. In some embodiments, the water seal height H12 set for the second-stage grading tank 20 is any one or any two of the following values: 750mm, 800mm, 900mm, 1000mm, 1100mm, 1200mm, 1300mm, 1400mm, 1500mm, 1600mm, 1700mm, 1800mm, 1900mm, 2000mm, 2100mm, 2200mm, 2300mm, 2400mm, and 2500mm. The water seal height H13 set for the third-stage grading tank 20 is in the range of 750mm to 2500mm. In some embodiments, the water seal height H13 set for the third-level grading tank 20 is a range of any one or any two of the following: 750mm, 800mm, 900mm, 1000mm, 1100mm, 1200mm, 1300mm, 1400mm, 1500mm, 1600mm, 1700mm, 1800mm, 1900mm, 2000mm, 2100mm, 2200mm, 2300mm, 2400mm, and 2500mm.

[0067] For example, taking the combustion treatment of combustible gas in three stages as an example, the water seal pressure range of the first-stage grading tank 20 is 0 kPa to 20 kPa. In some embodiments, the water seal pressure of the first-stage grading tank 20 is any one or any two of the following values: 0 kPa, 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, and 20 kPa. The water seal pressure range of the second-stage grading tank 20 is 7.5 kPa to 25 kPa. In some embodiments, the water seal pressure of the second-stage classifier 20 is within the range of any one or both of 7.5 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, 20 kPa, 21 kPa, 22 kPa, 23 kPa, 24 kPa, and 25 kPa. The water seal pressure of the third-stage classifier 20 ranges from 7.5 kPa to 25 kPa. In some embodiments, the water seal pressure of the third-stage grading tank 20 is a range of any one or any two of 7.5 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, 20 kPa, 21 kPa, 22 kPa, 23 kPa, 24 kPa, and 25 kPa.

[0068] In some embodiments, the grading tank 20 may also be equipped with a liquid level detection device 23. The liquid level detection device 23 is used to detect the liquid level height of the water seal medium in the water seal area 26 and / or, the liquid level height of the water seal medium in the non-water seal area 27. For example, a liquid level detection device 23 can be respectively installed on both sides of the baffle 21, so that the two liquid level detection devices 23 can respectively detect the liquid level height of the water seal medium in the water seal area 26 and the liquid level height of the water seal medium in the non-water seal area 27. In this way, by setting up the liquid level detection device 23 for liquid level detection, in conjunction with the first water supply valve 24 and the water discharge valve 22, the water seal height that generates the water seal pressure can be controlled more conveniently, thereby facilitating the staged combustion of combustible gases.

[0069] In some embodiments, the first inlet 201 of the grading tank 20 can be connected to the industrial water source 01 via a first water supply valve 24. The industrial water source 01 is used to provide industrial water. The grading tank 20 also has a second inlet 205 distributed in the water seal area 26. The second inlet 205 is connected to the outlet of the water storage tank 40 via a second water supply valve 25. The water storage tank 40 is positioned higher than the liquid level of the water seal medium in the water seal area 26, that is, the water storage tank 40 is a high-level water storage tank. In some embodiments, the bottom of the liquid level in the water storage tank 40 is higher than the highest liquid level of the water seal medium in the water seal area 26, and the height difference between the bottom of the liquid level in the water storage tank 40 and the highest liquid level of the water seal medium in the water seal area 26 is greater than or equal to 500 mm. The inlet of the water storage tank 40 can be connected to the industrial water source 01 via a third water supply valve 41. In this way, by setting up both the water storage tank 40 and the normal water supply pipeline, the water seal height can usually be established within 3 minutes, which can speed up the establishment of the water seal height. This allows the water seal height to be established quickly after each stage of discharge is completed, and the flare of that stage can be shut down.

[0070] In some embodiments, the staged combustion flare system may further include a distribution pipe 50. The distribution pipe 50 has multiple outlets 501, each corresponding to an inlet of a gas input pipe 202 of a staged tank 20. The distribution pipe 50 buffers the combustible gas to be burned and divides it into multiple paths through the outlets 501. In some embodiments, at least one pressure detection device 51 may be provided on the distribution pipe 50. The pressure detection device 51 is used to detect the pressure of the combustible gas to be burned. The pressure detection devices 51 may be distributed at different locations on the distribution pipe 50. The maximum pressure value detected by each pressure detection device 51 may be determined as the pressure of the combustible gas to be burned. Alternatively, the average pressure value detected by each pressure detection device 51 may be determined as the pressure of the combustible gas to be burned. This embodiment does not limit this. In some embodiments, the pressure detection devices 51 may be distributed at the upper, middle, and lower ends of the distribution pipe 50. The pressure detection range of each pressure detection device 51 is 0 kPa to 70 kPa. In some embodiments, the pressure detected by the pressure detection device 51 is a range of any one or any two of the following: 0 kPa, 5 kPa, 8 kPa, 10 kPa, 15 kPa, 18 kPa, 20 kPa, 25 kPa, 28 kPa, 30 kPa, 35 kPa, 38 kPa, 40 kPa, 45 kPa, 48 kPa, 50 kPa, 55 kPa, 58 kPa, 60 kPa, 65 kPa, 68 kPa, and 70 kPa.

[0071] In some embodiments, the staged combustion flare system may further include a liquid separator 60. The liquid separator 60 is connected to the distribution pipe 50 and is used to separate the liquid phase from the combustible gas to be burned. Specifically, the inlet of the liquid separator 60 may be connected to a combustible gas source 02, which provides the combustible gas to be burned. Thus, the combustible gas to be burned undergoes liquid phase filtration in the liquid separator 60 before entering the distribution pipe 50 for buffering. In some embodiments, a liquid level detection device 23 may also be provided on the liquid separator 60, which is used to detect the height of the separated liquid phase in the liquid separator 60.

[0072] In some embodiments, the staged combustion flare system may further include multiple water seal tanks 70. Each water seal tank 70 corresponds one-to-one with a multi-stage flare 10, and the water seal tank 70 is connected between the air inlet 101 of the corresponding flare 10 and the gas outlet 203 of the corresponding stage tank 20. The water seal tank 70 can be supplied with a water seal medium, such as industrial water, and the water seal height of the water seal medium can generate a corresponding water seal pressure. In this embodiment, the water seal pressure and water seal height generated by the water seal medium in the water seal tank 70 can also follow the above formula (1), which will not be elaborated further here.

[0073] The water seal tank 70 is used to perform flame arresting treatment on the corresponding flare 10 through water seal pressure. For example, the water seal height of the water seal medium can be 300 mm, and the corresponding water seal pressure is 3 kPa. Specifically, the inlet of the water seal tank 70 is connected to the gas outlet 203 of the grading tank 20, the outlet of the water seal tank 70 is connected to the air inlet 101 of the corresponding flare 10, the water inlet of the water seal tank 70 is connected to the industrial water source 01 through the fourth water supply valve 71, and the water outlet of the water seal tank 70 can be equipped with an overflow pipe to overflow water to a low-level sewage tank (or sewage tank). In some embodiments, a liquid level detection device 23 can be installed on the water seal tank 70 to detect the liquid level height of the water seal medium in the water seal tank 70. A pressure detection device 51 can also be installed on the connecting pipeline between the inlet of the water seal tank 70 and the gas outlet 203 of the grading tank 20 to detect the pressure of the combustible gas discharged from the grading tank 20.

[0074] In some embodiments, the air inlet 101 of each stage flare 10 can be connected to the inert gas source 03 through a corresponding inert gas purge valve 11. The inert gas purge valve 11 is used to open when the flare 10 is closed, so that inert gas can enter the flare 10 for purging protection. In some examples, the inert gas can be nitrogen. In this way, any combustible gas or combustion mixture remaining in the flare 10 can be discharged from the flare 10 in a timely manner, thereby avoiding any impact on the next combustion and improving safety.

[0075] In some embodiments of this application, the staged combustion flare system may further include a controller 30. The controller 30 can be used to control the liquid level of the water seal medium input into the staged tank 20, so that the water seal medium generates a set water seal pressure in the staged tank 20.

[0076] Specifically, the controller 30 can be connected to the drain valve 22, level detection device 23, first water supply valve 24, and second water supply valve 25 of each stage tank 20. The controller 30 establishes the water seal height of the corresponding stage tank 20 by controlling the opening of the first water supply valve 24 and the second water supply valve 25 and the closing of the drain valve 22. It controls the water seal height based on the detection value of the level detection device 23, and removes the water seal height of the corresponding stage tank 20 by controlling the closing of the first water supply valve 24 and the second water supply valve 25 and the opening of the drain valve 22. For example, the controller 30 can determine the water seal height of the stage tank 20 as the difference between the liquid level height measured by the level detection device 23 in the water-sealed area 26 and the liquid level height measured by the level detection device 23 in the non-water-sealed area 27. In this way, the controller 30 achieves grading by actively removing and establishing the water seal. The entire flare system does not consume additional pressure of the combustible gas to be burned, and the combustible gas to be burned does not need to break through the water seal medium of the grading tank 20. This ensures that the combustible gas to be burned reaches the outlet pressure of the flare head. In other words, the combustible gas to be burned concentrates the useful pressure on the combustion of the flare head, thereby improving the combustion effect.

[0077] For example, the controller 30 may control the opening of the drain valve 22 of the corresponding stage tank 20 based on the pressure range of the combustible gas to be burned.

[0078] Specifically, the controller 30 first determines the target grading tank to be put into use from each of the grading tanks 20 arranged in parallel with the multi-stage flares 10, based on the pressure range of the combustible gas to be burned.

[0079] Then, the controller 30 controls the water drain valve 22 of the target grading tank to open, so that the liquid level of the water seal medium in the target grading tank is lowered until the outlet of the gas input pipe 202 of the target grading tank is exposed. In this way, the combustible gas to be burned can be discharged from the outlet of the gas input pipe 202 to the gas outlet 203 of the target grading tank, and then input from the gas outlet 203 into the air inlet 101 of the corresponding torch 10 of the target grading tank for combustion.

[0080] In some embodiments, the controller 30 can compare the pressure of the combustible gas to be burned with the preset pressure threshold corresponding to each stage tank 20 of the multi-stage flare 10, and then determine the stage tank 20 whose preset pressure threshold is less than the pressure of the combustible gas to be burned as the target stage tank to be put into use.

[0081] If there are multiple target grading tanks to be put into use, the controller 30 can remove the water seal medium of the target grading tanks sequentially according to a preset time interval, or it can remove the water seal medium of one of the target grading tanks first, and then, after a preset time interval, re-determine the target grading tanks to be put into use based on the pressure range of the combustible gas to be burned, and remove the water seal medium of the corresponding target grading tank.

[0082] In some examples, the controller 30 can periodically compare the pressure of the combustible gas to be burned with the preset pressure threshold corresponding to each stage tank 20 of the multi-stage flare 10. If the pressure of the combustible gas to be burned is greater than the preset pressure threshold P1 corresponding to the first stage stage tank 20, then the first stage stage tank 20 is identified as the target stage tank to be put into use, and the water seal medium of the first stage stage tank 20 is removed, so that the combustible gas to be burned is discharged into the first stage flare 10 for combustion.

[0083] As the amount of combustible gas to be burned increases, if the pressure of the combustible gas to be burned is greater than the preset pressure threshold P2 corresponding to the second-stage grading tank 20, then the second-stage grading tank 20 is simultaneously identified as the target grading tank to be put into use, and the water seal medium of the second-stage grading tank 20 is removed, so that the combustible gas to be burned is discharged into the second-stage flare 10 for combustion treatment. At this time, the first-stage flare 10 and the second-stage flare 10 are put into use at the same time.

[0084] As the amount of combustible gas to be burned continues to increase, if the pressure of the combustible gas to be burned is greater than the preset pressure threshold P3 corresponding to the third-stage grading tank 20, then the third-stage grading tank 20 is simultaneously identified as the target grading tank to be put into use, and the water seal medium of the third-stage grading tank 20 is removed, so that the combustible gas to be burned is discharged into the third-stage flare 10 for combustion treatment. At this time, the first-stage flare 10, the second-stage flare 10 and the third-stage flare 10 are put into use at the same time.

[0085] As the emission of combustible gas decreases, if the pressure of the combustible gas is less than the preset pressure threshold P3 corresponding to the third-stage stage tank 20, the first water supply valve 24 and the second water supply valve 25 of the third-stage stage tank 20 are opened, and the water withdrawal valve 22 is closed to establish the water seal medium in the third-stage stage tank 20, thereby shutting off the third-stage flare 10. At this time, the first-stage flare 10 and the second-stage flare 10 are simultaneously activated, while the third-stage flare 10 is not activated. Other changes in emission levels and the number of stages can be deduced from the above example and will not be elaborated here.

[0086] By using the controller 30 in conjunction with the staged tank 20, the staged switching of the combustible gas to be burned is indirectly achieved by controlling the water seal height of the water seal medium. When the emission of the combustible gas to be burned is small, the combustible gas to be burned is forced into the next stage by the water seal pressure. As the emission of the combustible gas to be burned increases, when the pressure reaches a certain value, the water removal valve 22 on the staged tank 20 can be opened in time to remove the water seal medium and put the flare 10 of that stage into operation. In this way, the staged control is achieved by using the water seal medium, which makes the specifications of the staged channel unrestricted, and thus does not limit the emission of combustible gas staged combustion, and can simultaneously meet the treatment needs of combustible gases with large and small emission volumes.

[0087] In some embodiments, the controller 30 may also be connected to each pressure detection device 51 on the distribution pipe 50, thereby determining the pressure of the combustible gas to be burned based on the pressure values ​​detected by each pressure detection device 51 on the distribution pipe 50. Specifically, the controller 30 may determine the pressure of the combustible gas to be burned as the maximum value among the pressure values ​​detected by each pressure detection device 51. Alternatively, the average value of the pressure values ​​detected by each pressure detection device 51 may be determined as the pressure of the combustible gas to be burned. This application embodiment does not limit this.

[0088] By using the controller 30 in conjunction with the distribution pipe 50, combustible gas can enter the large space of the distribution pipe 50 for sufficient buffering and be distributed through branch pipes. The pressure detection device 51 installed on the distribution pipe 50 can detect its pressure. The controller 30 can control the number of stages of staged combustion based on the pressure detected by the pressure detection device 51 on the distribution pipe 50, thereby achieving better staged control.

[0089] In some embodiments, the controller 30 may also be connected to the liquid level detection device 23, the pressure detection device 51 and the fourth water supply valve 71 on the water seal tank 70, for controlling and adjusting the water seal height of the water seal medium in the water seal tank 70.

[0090] By using the controller 30 in conjunction with the water seal tank 70, the functions of separating liquid droplets and preventing backfire can be better achieved.

[0091] In some embodiments, the controller 30 may also be connected to the inert gas purge valve 11 to control the inert gas purge valve 11 to open when the torch 10 is detected to be shut off, and to control the inert gas purge valve 11 to close after the purge protection is completed.

[0092] By setting the controller 30, the automatic control of the staged combustion flare system can be realized, which makes the establishment and removal of the water seal height in the staged tank 20 very quick and convenient, and is also more conducive to the adjustment and commissioning of staged combustion, with high practicality and ease of operation.

[0093] Specifically, the embodiment provided in the accompanying drawings of this application is illustrated. In this embodiment, each grading tank 20 has been pre-filled with water seal medium to a preset water seal height. The combustible gas to be burned emitted from the combustible gas source 02 is separated by the liquid separator 60 and then enters the distribution pipe 50. The pressure is detected and analyzed by the pressure detection device 51 on the pipe. For example, the maximum value among three pressure values ​​can be taken as the pressure of the combustible gas to be burned. If the pressure of the combustible gas to be burned is greater than 13 kPa (adjustable), the water drain valve 22 of the first-stage grading tank 20 is opened to remove the water seal medium of the first-stage grading tank 20. The combustible gas to be burned is discharged into the first-stage grading tank 20, passes through the first-stage water seal tank 70, and is discharged into the first-stage flare 10 for combustion. At this time, only the first-stage flare 10 is put into use.

[0094] After a 5-minute delay, pressure is detected and analyzed using the pressure detection device 51 on the distribution pipe 50. If the pressure of the combustible gas to be burned is still greater than 13 kPa (adjustable), it is confirmed that the water drain valve 22 of the first-stage grading tank 20 is open. At the same time, the water drain valve 22 of the second-stage grading tank 20 is opened to remove the water seal medium of the second-stage grading tank 20. The combustible gas to be burned is discharged into the second-stage grading tank 20, passes through the second-stage water seal tank 70, and is discharged into the second-stage flare 10 for combustion. At this time, both the first-stage flare 10 and the second-stage flare 10 are put into use.

[0095] After a 5-minute delay, pressure detection and analysis are performed using the pressure detection device 51 on the distribution pipe 50. If the pressure of the combustible gas to be burned is still greater than 13 kPa (adjustable), it is confirmed that the water drain valves 22 of the first-stage grading tank 20 and the second-stage grading tank 20 are both open. At the same time, the water drain valve 22 of the third-stage grading tank 20 is opened to remove the water seal medium of the third-stage grading tank 20. The combustible gas to be burned is discharged into the third-stage grading tank 20, passes through the third-stage water seal tank 70, and is discharged into the third-stage flare 10 for combustion. At this time, the first-stage flare 10, the second-stage flare 10, and the third-stage flare 10 are all put into use.

[0096] If the emission of the combustible gas to be burned decreases, and the pressure of the combustible gas to be burned is detected as lower than 10 kPa by the pressure detection device 51 on the distribution pipe 50, then the drain valve 22 of the third-stage grading tank 20 is closed, and the first water supply valve 24 and the second water supply valve 25 of the third-stage grading tank 20 are opened to establish a water seal height H13, thereby shutting off the third-stage flare 10. At the same time, the inert gas purging valve 11 is opened to purge the third-stage flare 10 with inert gas for protection.

[0097] When the pressure of the combustible gas to be burned is detected to be lower than 7.5 kPa by the pressure detection device 51 on the distribution pipe 50, and the water seal height is detected to be not less than H13 by the liquid level detection device 23 on the third-stage grading tank 20, the drain valve 22 of the second-stage grading tank 20 is closed, and the first water supply valve 24 and the second water supply valve 25 of the second-stage grading tank 20 are opened to establish a water seal height H12, thereby shutting off the second-stage flare 10. At the same time, the inert gas purging valve 11 is opened to purge the second-stage flare 10 with inert gas for protection.

[0098] When the pressure of the combustible gas to be burned is detected to be lower than 4.5 kPa by the pressure detection device 51 on the distribution pipe 50, and the water seal height is not less than H13 by the liquid level detection device 23 on the third-stage grading tank 20 and not less than H12 by the liquid level detection device 23 on the second-stage grading tank 20, the drain valve 22 of the first-stage grading tank 20 is closed after a 1-minute delay, and the first water supply valve 24 and the second water supply valve 25 of the first-stage grading tank 20 are opened to establish a water seal height of H11, thereby shutting off the first-stage flare 10. At the same time, the inert gas purging valve 11 is opened to purge the first-stage flare 10 with inert gas for protection.

[0099] Additionally, when it is necessary to switch the grading system and flare commissioning sequence, this can be done by adjusting the set water seal height. For example, after one year of operation of the first-stage grading tank, the first and second stages can be switched. Specifically, the water seal height of the first-stage grading tank 20 is increased from H11 to H12, and the water seal height of the second-stage grading tank 20 is decreased from H12 to H11, thus achieving the switch between the first and second stages. When it is necessary to switch the third stage back to the first stage, simply adjust H13 to H11 as described above.

[0100] Understandably, the entire system can control the release of the corresponding flare 10 according to the pressure of the combustible gas to be burned, and use the water seal medium of the stage tank 20 to achieve stage control, so that the specifications of the stage channel are not restricted, and thus the emission of combustible gas stage combustion is not restricted, and the treatment needs of combustible gas with large emission volume and small emission volume can be taken into account at the same time.

[0101] Accordingly, this application also provides a staged combustion method for a flare system employing the above-described staged combustion, the method comprising the following steps:

[0102] Based on the pressure range of the combustible gas to be burned, the controller 30 determines the target grading tank to be put into use from each of the grading tanks 20 arranged in parallel with the multi-stage flares 10.

[0103] The controller 30 controls the liquid level of the water seal medium in the target grading tank to decrease until the outlet of the gas input pipe 202 of the target grading tank is exposed, so that the combustible gas to be burned output from the outlet of the gas input pipe 202 passes through the gas outlet 203 of the target grading tank and enters the gas inlet 101 of the corresponding torch 10 of the target grading tank for combustion.

[0104] In some embodiments, the controller 30 determines the target grading tank to be put into use from each of the parallel-arranged grading tanks 20 corresponding to the multi-stage flares 10, based on the pressure range of the combustible gas to be burned, including:

[0105] The controller 30 compares the pressure of the combustible gas to be burned with the preset pressure threshold corresponding to each stage tank 20 of the multi-stage flare 10.

[0106] The controller 30 identifies the grading tank 20 whose preset pressure threshold is less than the pressure of the combustible gas to be burned as the target grading tank to be put into use.

[0107] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0108] The staged combustion flare system and staged combustion method provided in the embodiments of this application have been described in detail above, and specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A staged combustion flare system, characterized in that, include: Multiple grading tanks (20) are arranged side by side. Each grading tank (20) has a first water inlet (201), a gas input pipe (202), and a gas outlet (203). The first water inlet (201) is used to input a water seal medium. The gas input pipe (202) extends from the outer wall of the grading tank (20) toward the liquid surface of the water seal medium and is used to input combustible gas to be burned. A baffle (21) is provided inside the grading tank (20). One side of the baffle (21) is flush with a portion of the interior of the grading tank (20). A water-sealed area (26) is formed by the wall enclosure, and a non-water-sealed area (27) is formed by the other side of the baffle (21) and part of the inner wall of the grading tank (20); the water-sealed area (26) and the non-water-sealed area (27) are connected by a drain valve (22), which is used to divert the water-sealed medium in the water-sealed area (26) to the non-water-sealed area (27); the non-water-sealed area (27) is also provided with an overflow pipe, which is used to maintain the liquid level of the water-sealed medium in the non-water-sealed area (27) at a preset height; A multi-stage flare (10) is arranged in parallel. Each flare (10) has an air inlet (101). The air inlets (101) of the multiple flares (10) are connected one-to-one with the gas outlets (203) of the multiple stage tanks (20). When the water seal medium is introduced into the grading tank (20), the outlet of the gas input pipe (202) is located inside the water seal medium. The water seal medium has a set water seal pressure, and the combustible gas to be burned has a discharge pressure. The set water seal pressure is greater than the discharge pressure to prevent the combustible gas to be burned from breaking through the water seal medium and being discharged into the corresponding torch (10) through the gas outlet (203).

2. The staged combustion flare system according to claim 1, characterized in that, The grading tank (20) also has an outlet (204), the first inlet (201) is distributed in the water seal area (26), and the outlet (204) is distributed in the non-water seal area (27). The difference between the liquid level of the water seal medium in the water seal area (26) and the liquid level of the water seal medium in the non-water seal area (27) is configured as the water seal height that generates the water seal pressure.

3. The staged combustion flare system according to claim 2, characterized in that, The water seal height is set differently for each of the grading tanks (20).

4. The staged combustion flare system according to claim 2, characterized in that, The grading tank (20) is also equipped with a liquid level detection device (23), which is used to detect the liquid level height of the water seal medium in the water seal area (26) and / or detect the liquid level height of the water seal medium in the non-water seal area (27).

5. The staged combustion flare system according to claim 2, characterized in that, The first water inlet (201) is connected to the industrial water source through the first water supply valve (24); The grading tank (20) also has a second inlet (205) distributed in the water seal area (26). The second inlet (205) is connected to the outlet of the water storage tank (40) through a second water supply valve (25). The water storage tank (40) is positioned higher than the liquid level of the water seal medium in the water seal area (26).

6. The staged combustion flare system according to claim 1, characterized in that, The staged combustion flare system also includes: The distribution pipe (50) has multiple gas outlets (501), which are connected one-to-one with the inlets of the gas input pipes (202) of the multiple stage tanks (20). The distribution pipe (50) is used to buffer the combustible gas to be burned and to divide the combustible gas to be burned into multiple paths through the multiple gas outlets (501).

7. The staged combustion flare system according to claim 6, characterized in that, At least one pressure detection device (51) is provided on the distribution pipe (50), and the pressure detection device (51) is used to detect the pressure of the combustible gas to be burned.

8. The staged combustion flare system according to claim 6, characterized in that, The staged combustion flare system also includes: The liquid separator (60) is connected to the distribution pipe (50) and is used to separate the liquid phase in the combustible gas to be burned.

9. The staged combustion flare system according to claim 1, characterized in that, The staged combustion flare system also includes: Multiple water seal tanks (70) are provided, each corresponding to a different stage of the torch (10). Each water seal tank (70) is connected between the air inlet (101) of the corresponding torch (10) and the gas outlet (203) of the corresponding stage tank (20). The water seal tanks (70) are used to perform flame arresting treatment on the corresponding torch (10).

10. The staged combustion flare system according to claim 1, characterized in that, The air inlet (101) of each torch (10) is connected to an inert gas source through a corresponding inert gas purging valve (11). The inert gas purging valve (11) is used to open when the torch (10) is closed, so that inert gas enters the torch (10) for purging protection.

11. The staged combustion flare system according to claim 1, characterized in that, All of the torches (10) mentioned above are elevated torches.

12. The staged combustion flare system according to any one of claims 1-11, characterized in that, The staged combustion flare system also includes: The controller (30) is used to control the liquid level of the water seal medium in the grading tank (20) so that the water seal medium generates a set water seal pressure in the grading tank (20).

13. A staged combustion method, characterized in that, The flare system employing staged combustion as described in any one of claims 1-12 includes the following steps: The controller (30) determines the target grading tank to be put into use from each of the grading tanks (20) arranged in parallel with the multi-stage flares (10) based on the pressure range of the combustible gas to be burned. The controller (30) controls the liquid level of the water seal medium in the target grading tank to decrease until the outlet of the gas input pipe (202) of the target grading tank is exposed, so that the combustible gas to be burned output from the outlet of the gas input pipe (202) passes through the gas outlet (203) of the target grading tank and is input into the air inlet (101) of the corresponding torch (10) of the target grading tank for combustion.

14. The staged combustion method according to claim 13, characterized in that, The controller (30) determines the target grading tank to be put into use from each of the parallel-arranged grading tanks (20) corresponding to the multi-stage flares (10) based on the pressure range of the combustible gas to be burned, including: The controller (30) compares the pressure of the combustible gas to be burned with the preset pressure threshold corresponding to each stage tank (20) of the multi-stage flare (10); The controller (30) identifies the graded tank (20) whose preset pressure threshold is less than the pressure of the combustible gas to be burned as the target graded tank to be put into use.

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