CN113623657A

CN113623657A - Low-nitrogen ground flare system for LNG receiving station

Info

Publication number: CN113623657A
Application number: CN202110949532.XA
Authority: CN
Inventors: 郭宏新; 何松; 李同; 王建果; 刘丰; 孟凯; 钟宇航
Original assignee: Jiangsu Sunpower Technology Co Ltd
Current assignee: Jiangsu Sunpower Technology Co Ltd
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2021-11-09

Abstract

The utility model provides a LNG receiving station is with low nitrogen ground torch system, includes barrel, prevent wind wall, the special low nitrogen combustor equipment of many sets of LNG and combustor grading system. The LNG special low-nitrogen combustor comprises a gas inlet pipe, a combustor branch, gas spray holes, flame stabilizing holes, an annular pipe, an air/steam inlet pipe, air/steam spray holes and a connecting plate. The LNG special low-nitrogen combustor enables flare waste gas to realize staged combustion through the differentiated reasonable arrangement of the aperture of a gas spray hole, the opening angle and the opening position, so that the combustion high-temperature area is reduced. The ground flare system combustor is arranged in the hollow annular space in the cylinder, so that the air distribution at the center and the edge of the cylinder is effectively increased, the overall combustion temperature is reduced, the emission of NOx is further reduced, and the service life of the system is prolonged. The system is suitable for the characteristics of low temperature, high pressure and light components of the flare gas in the LNG industry, and can also be used for treating other light-component ground flare waste gas which is difficult to smoke.

Description

Low-nitrogen ground flare system for LNG receiving station

Technical Field

The invention relates to a waste gas treatment technology, in particular to a natural gas flare waste gas combustion technology, and specifically relates to a low-nitrogen ground flare system for an LNG receiving station.

Technical Field

With the increasing attention of the nation to environmental protection, the LNG industry is rapidly developed in recent years, in the daily operation process of an LNG receiving station, a large amount of combustible gas can be generated by operations such as unloading, gasification, transportation, tank dumping and the like of an LNG ship, and the gas has the characteristics of low temperature, high pressure, light components and the like.

For natural gas generated by LNG gasification, the main pollutant component in the combustion product is NOx, and with the stricter and stricter national restrictions on pollutant emission, the ground flare system applicable to the LNG industry needs to meet the requirements of low nitrogen emission in addition to stable combustion.

The invention provides a low-nitrogen ground flare system for an LNG receiving station, which is based on the characteristics of low temperature, high pressure and light components of combustible gas of the LNG receiving station and simultaneously considers low-nitrogen emission.

Disclosure of Invention

The invention aims to design a low-nitrogen ground flare system for an LNG receiving station, aiming at the problems that fuel gas generated by LNG gasification has low temperature, higher pressure relative to other flare gases, lighter components, large combustion difficulty and serious pollution, and simultaneously considering the requirement of low-nitrogen combustion.

The technical scheme of the invention is as follows:

the utility model provides a LNG receiving station is with low nitrogen ground torch system, its characterized in that, it includes barrel 1, prevent wind wall 2 and LNG low nitrogen combustor 3, barrel 1 is arranged in preventing wind wall 2 and raises certain height as inlet air channel, and the lower part of barrel 1 is equipped with natural wind inlet air channel promptly, and LNG low nitrogen combustor 3 arranges in barrel 1 bottom cavity annular space, and LNG low nitrogen combustor 3 is controlled by combustor hierarchical control system.

The LNG low-nitrogen combustor 3 is characterized in that 3-8 combustor branches 5 are arranged at the top of a gas inlet pipe 4 of the LNG low-nitrogen combustor 3, gas spray holes 6 are formed in the combustor branches 5 and are divided into 2-3 rows, the size and the direction of each row of holes are different, an air/steam inlet pipe 8 is connected with an annular pipe 9, air/steam spray holes 10 are formed in the annular pipe 9, and the annular pipe 9 and the gas inlet pipe 4 are fixed through a connecting plate 11; the ring pipe 9 is located below the burner branch 5.

The gas jet holes 6 are divided into a first row of gas jet holes 6a and a second row of gas jet holes 6b which are arranged on each combustor branch 5, wherein the first row of gas jet holes 6a are large in hole and have the diameter range of 4-9 mm, the axial direction of the hole forms an included angle of 0-20 degrees with the vertical direction, the second row of gas jet holes 6b are small in hole and have the diameter range of 2.5-5 mm, and the axial direction of the hole forms an included angle of 10-30 degrees with the vertical direction.

The branch 5 of the partial combustor is provided with a first row of gas spray holes 6a and a second row of gas spray holes 6b, the root part of the branch is also provided with a flame stabilizing hole 7, and when the gas pressure is more than or equal to 15kPa, the flame stabilizing hole 7 plays a role of stabilizing flame, so that the flame is not deflagrated, and the burnout rate of the flare gas is ensured.

In addition, compressed air or steam is additionally arranged to reinforce combustion air supply inside the LNG low-nitrogen combustor 3, the compressed air or the steam enters the annular pipe 9 through the air/steam inlet pipe 8, a plurality of groups of air/steam spray holes 10 are formed in the annular pipe 9, the diameter range of the air/steam spray holes 10 is 2-4 mm, the air/steam spray holes are close to the fuel gas spray holes 6, and the horizontal distance is not more than 60 mm.

The LNG low-nitrogen combustor 3 is opened by a combustor grading control system in grades respectively, wherein 2-8 sets of combustors are arranged at the first stage, 4-16 sets of combustors are arranged at the second stage, 8-24 sets of combustors are arranged at the third stage, and the rest stages are correspondingly arranged according to the ground torch handling capacity, wherein 1-3 flame-transmitting holes 12 are arranged at the end parts of adjacent combustor branches 5 opposite to and adjacent to adjacent combustors in the second-third stages, so that the ground torch waste gas can be ignited in time and is sufficiently treated in time; thereby ensuring that the discharge amount of the nitrogen oxides in the whole ground flare system is less than or equal to 25 ppm.

The invention has the beneficial effects that:

the ground flare system combustor is arranged in the hollow annular space in the cylinder, so that the air distribution at the center and the edge of the cylinder is effectively increased, the overall combustion temperature is reduced, the emission of NOx is further reduced, and the service life of the system is prolonged.

The invention is suitable for the characteristics of low temperature, high pressure and light components of the flare gas in the LNG industry, and can also be used for treating other light-component ground flare waste gas which is difficult to smoke.

Drawings

FIG. 1 is a schematic diagram of a low-nitrogen ground flare system for an LNG receiving station according to the present invention;

FIG. 2 is a schematic structural diagram of a LNG special low-nitrogen burner according to the present invention;

FIG. 3 is a schematic diagram of the operation of the low-nitrogen ground flare system for an LNG receiving station according to the present invention;

FIG. 4 is a diagram of the arrangement of the flame transfer holes between adjacent burners according to the present invention.

Wherein: 1-a cylinder body; 2-a windproof wall; 3-LNG low-nitrogen combustor; 4-a gas inlet pipe; 5-a burner branch; 6-gas spraying holes; 7-flame stabilizing holes; 8-air/steam inlet pipe; 9-ring pipe; 10-air/steam jet; 11-a connecting plate; 12-flame transfer holes.

Two rows of gas spray holes are formed in each

combustor branch

5, 6a is a first row of gas spray holes, 6b is a second row of gas spray holes, and the diameters of the 6a and the 6b are different.

Detailed Description

The invention is further illustrated by the following structural figures and examples.

Example 1.

The combustor of ground flare system arranges in the barrel bottom, so often can produce a large amount of NOx in the combustion process because the central zone combustor air distribution is not enough, simultaneously, the barrel is inside still can cause a section of thick bamboo high temperature owing to the air distribution is not enough, influences the life of system.

In order to solve the above-mentioned problems, the present invention proposes the following embodiments. Referring to fig. 1, a low-nitrogen ground flare system for an LNG receiving station comprises a barrel 1, a windproof wall 2 and an LNG low-nitrogen burner 3, wherein the barrel 1 is positioned in the windproof wall 2 and is elevated by a certain height to serve as an air inlet channel, namely, the lower part of the barrel 1 is provided with a natural air inlet channel, the LNG low-nitrogen burner 3 is arranged in a hollow annular space at the bottom of the barrel 1, and the LNG low-nitrogen burner 3 is controlled by a burner grading control system. The combustor is not arranged in barrel 1 internal combustion ware cavity annular space in the barrel and central region 1 ~ 5m space, also do not arrange the combustor near wall department 1 ~ 3 m), this mode can make barrel 1 internal center region air distribution increase, the problem of traditional ground torch system center oxygen deficiency has been solved, make the burning more complete, reduce NOx's emission, be close to wall department simultaneously and do not arrange the combustor, sufficient air cooling has 1 internal combustion temperature of barrel, the system life has been prolonged.

The invention adopts the LNG low-nitrogen burner 3 besides the hollow burner arrangement mode. Referring to fig. 2, the LNG low-nitrogen combustor 3 has the outer diameter of 320-550 mm, fuel gas enters each combustor branch 5 through the fuel gas inlet pipe 4, the combustor branches 5 are uniformly distributed along the circumferential direction, the number of the branches is 3-8, and two rows of fuel gas spray holes 6 are formed in the combustor branches 5 along the radial direction. The gas spray holes 6 are divided into gas spray holes 6a and gas spray holes 6b, wherein the first row of gas spray holes 6a are large in diameter range of 4-9 mm, the axial direction of the holes forms an included angle of 0-20 degrees with the vertical direction, the second row of gas spray holes 6b are small in diameter range of 2.5-5 mm, and the axial direction of the holes forms an included angle of 10-30 degrees with the vertical direction. Most of the fuel gas is sprayed out from the fuel gas spray holes 6a, and a small part of the fuel gas is sprayed out from the fuel gas spray holes 6b with smaller apertures, so that the flare gas is obviously combusted in a grading way, thereby reducing a local high-temperature area, and in addition, LNG waste gas is sprayed out from the spray holes 6, so that a large amount of ambient air can be entrained and absorbed to participate in combustion, and the combustion temperature is reduced, thereby reducing the emission of nitrogen oxides. The branch 5 of the partial combustor is provided with

gas spray holes

6a and 6b and a flame stabilizing hole 7, and when the gas pressure is higher (more than or equal to 15 kPa), the flame stabilizing hole 7 can play a role in stabilizing flame, so that the flame does not misfire, and the burnout rate of the flare gas is ensured.

Furthermore, the invention is additionally provided with compressed air or steam to strengthen the combustion air supply in the combustor. Compressed air or steam pass through air/steam inlet pipe 8 and get into ring canal 9, set up a plurality of groups air/steam orifice 10 on the ring canal 9, compressed air or steam pass through orifice 10 high-speed injection into the inside problem that can alleviate the inside air not enough of flame, it is more even to increase turbulence disturbance and make air and gas mixture, further reduce flame temperature and high temperature district scope size, reduce the dwell time of nitrogen oxide in the high temperature district, thereby further reduce nitrogen oxide formation and emission by a wide margin. The diameter range of the air/steam jet holes 10 is 2-4 mm, the air/steam jet holes are arranged close to the fuel gas jet holes 6, and the horizontal distance is not more than 60 mm. The ring pipe 9 is fixed with the gas inlet pipe 4 through a connecting plate 11.

Furthermore, the special combustors 3 are respectively started by a combustor grading control system in grades, wherein 2-8 sets of combustors are arranged at the first stage, 4-16 sets of combustors are arranged at the second stage, 8-24 sets of combustors are arranged at the third stage, the rest stages are correspondingly arranged according to the ground torch handling capacity, and 1-3 flame transmission holes are arranged in the branches 5 right opposite to the adjacent combustors in the 2-3 stages and the interstage stages, so that the ground torch waste gas can be timely ignited and timely and fully treated.

The technical scheme ensures that the discharge amount of the nitrogen oxides of the whole low-nitrogen ground flare system for the LNG receiving station is less than or equal to 25 ppm.

Example 2

As shown in figure 3, 20 sets of LNG low-nitrogen burners 3 are arranged in a cylinder of a low-nitrogen ground flare system for an LNG receiving station, the LNG low-nitrogen burners are numbered 1-20, wherein 1-4 are first-stage burners, 5-8 are second-stage burners, 9-20 are third-stage burners (more burners and more stages can be arranged when the treatment capacity is larger), a switch valve is arranged at the upstream of each stage of branch pipe except the first-stage burners (normally opened by the first-stage burners), and the switch valves are controlled by a hierarchical control system. The method comprises the steps that fuel gas discharged from the upstream enters a main pipe and then enters a first stage for combustion, meanwhile, a grading control system detects the pressure of a branch pipe of the first stage in real time, if the pressure is high, the grading control system judges that the fuel gas exceeds the processing capacity of the first stage, immediately, the grading control system automatically opens a switch valve of a second stage, at the moment, the first stage and the second stage simultaneously process the fuel gas, and if the grading control system detects that the pressure is still high, a switch valve of a third stage is opened. Meanwhile, if the grading control system detects that the pressure in the branch pipe is suddenly reduced during the operation of the flare system, the grading control system closes (from the third stage to the second stage) the switch valves in sequence. The arrangement of the adjacent burners in the stage and the adjacent burners in the stage makes the branches with the flame transfer holes 12 opposite as much as possible, as shown in fig. 4, and the arrangement has the advantage that when one set of burners is ignited, the flame of the burner can ignite the adjacent burners through the flame transfer holes, so that the ignition reliability of the whole system is improved, and generally, one LNG low-nitrogen burner 3 needs to arrange the flame transfer holes 12 on both burner branches 5 to meet the ignition between the adjacent burner branches 5 in the stage and the ignition of the adjacent burner branches 5 in the stage.

The foregoing description is only a preferred embodiment of the present invention and is not intended to limit the present invention in any way, and many modifications and variations will be apparent to those skilled in the art. Any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention are still within the scope of the technical solution of the present invention.

The invention is not concerned with parts that are the same as or can be implemented using the same technology as the prior art.

Claims

1. The utility model provides a LNG receiving station is with low nitrogen ground torch system, its characterized in that, it includes barrel (1), prevent wind wall (2) and LNG low nitrogen combustor (3), barrel (1) is arranged in preventing wind wall (2) and lifts by a take the altitude as inlet air channel, and the lower part of barrel (1) is equipped with natural wind inlet air channel promptly, and LNG low nitrogen combustor (3) are arranged in barrel (1) bottom cavity annular space, and LNG low nitrogen combustor (3) are controlled by combustor hierarchical control system.

2. The LNG receiving station low-nitrogen ground flare system according to claim 1, wherein 3-8 burner branches (5) are arranged at the top of a gas inlet pipe (4) of the LNG low-nitrogen burner (3), the burner branches (5) are provided with gas spray holes (6), the gas spray holes are divided into 2-3 rows, the size and direction of each row of holes are different, the air/steam inlet pipe (8) is connected with a ring pipe (9), the ring pipe (9) is provided with air/steam spray holes (10), and the ring pipe (9) and the gas inlet pipe (4) are fixed through a connecting plate (11); the ring pipe (9) is positioned at the lower part of the burner branch (5).

3. The low-nitrogen ground flare system for the LNG receiving station according to claim 2, wherein the gas injection holes (6) are divided into a first row of gas injection holes (6 a) and a second row of gas injection holes (6 b) and are arranged on each burner branch (5), wherein the first row of gas injection holes (6 a) have a larger hole diameter range of 4-9 mm, the axial direction of the hole has an included angle of 0-20 degrees with the vertical direction, the second row of gas injection holes (6 b) have a smaller hole diameter range of 2.5-5 mm, and the axial direction of the hole has an included angle of 10-30 degrees with the vertical direction.

4. The low-nitrogen ground flare system for the LNG receiving station according to claim 2, wherein the partial burner branches (5) are provided with a first row of gas spray holes (6 a) and a second row of gas spray holes (6 b), the root parts of the partial burner branches are also provided with flame stabilizing holes (7), and when the gas pressure is larger than or equal to 15kPa, the flame stabilizing holes (7) play a role in stabilizing flame, so that the flame is not ignited, and the burnout rate of flare gas is ensured.

5. The LNG receiving station low-nitrogen ground flare system as claimed in claim 2, wherein compressed air or steam is additionally added to reinforce combustion air supply inside the LNG low-nitrogen combustor (3), the compressed air or steam enters the circular pipe (9) through the air/steam inlet pipe (8), a plurality of groups of air/steam jet holes (10) are formed in the circular pipe (9), the diameter range of the air/steam jet holes (10) is 2-4 mm, the air/steam jet holes are arranged close to the gas jet holes 6, and the horizontal distance is not more than 60 mm.

6. The LNG receiving station used low-nitrogen ground flare system according to claim 1, characterized in that LNG low-nitrogen burners (3) are respectively opened by a burner grading control system in grades, wherein the first stage is provided with 2-8 sets of burners, the second stage is provided with 4-16 sets of burners, the third stage is provided with 8-24 sets of burners, the rest stages are correspondingly arranged according to ground flare treatment amount, wherein 1-3 flame-transmitting holes (12) are arranged at the end part of a branch (5) of the adjacent burners in the second-third stage and opposite to the adjacent burners in the interstage, and the ground flare waste gas can be ignited in time and fully treated in time; thereby ensuring that the discharge amount of the nitrogen oxides in the whole ground flare system is less than or equal to 25 ppm.