A gas burner system and working method thereof

Abstract

The present invention discloses a gas burner system and a working method thereof. The gas burner system comprises: an air supply duct, a smoke return mixing cylinder, an inner cylinder, a blunt body, a first fuel supply system and a second fuel supply system; the air supply duct comprises an air outlet; the smoke return mixing cylinder is sleeved outside the air outlet, and the channel between the smoke return mixing cylinder and the air outlet cylinder constitutes a smoke return channel; the inner cylinder is sleeved inside the air outlet cylinder, and the channel between the smoke return mixing cylinder and the air outlet cylinder constitutes an air nozzle; the blunt body is placed downstream of the inner cylinder; the first fuel supply system is arranged inside the air supply duct, and comprises two groups of branch pipes respectively located inside and outside the inner cylinder, and the ends of the two groups of branch pipes are respectively connected to the inner branch nozzle and the outer branch nozzle; the second fuel supply system is arranged outside the air supply duct, and comprises two groups of outer nozzles spraying fuel toward the center at different angles. The present invention mixes the gas with the inert combustion products before combustion occurs, greatly reducing the peak temperature of the composition, thereby inhibiting the generation of NOx in the industrial gas burner.

Description

Technical Field

[0001] The present invention relates to the technical field of burners, and particularly to a gas burner system and its working method. Background Art

[0002] As the national environmental protection policies become increasingly strict, the requirements for nitrogen oxide emissions from boilers are also getting higher and higher. For the combustion of gas, the formation mechanism of NOx is mainly thermal, that is, when the flame temperature is high enough, the covalent bond of N2 will be broken to obtain free N ions, which combine with oxygen atoms to form NOx. Summary of the Invention

[0003] The main object of the present invention is to provide a gas burner system and its working method, which are used to mix gas with inert combustion products before combustion by technical means, greatly reduce the peak temperature of the composition, and thus inhibit the formation of NOx in industrial gas burners.

[0004] To achieve the above-mentioned invention object, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, a gas burner system is provided, including:

[0006] An air supply duct, which is composed of a large-diameter air duct, a reduced-diameter pipe with a reduced diameter, and a small-diameter air outlet duct. The large end of the reduced-diameter pipe is connected to the air duct, and the small end is connected to the air outlet duct;

[0007] A flue gas recirculation mixing cylinder, which is sleeved outside the air outlet duct and is composed of a reduced-diameter recirculation part, a small-diameter throat part, and an enlarged-diameter diffuser part. The upstream of the throat is connected to the outlet of the recirculation part, and the downstream is connected to the inlet of the diffuser part; the channel between the flue gas recirculation mixing cylinder and the air outlet duct forms a flue gas recirculation channel;

[0008] An inner cylinder, which is hollow inside and is sleeved inside the air outlet duct; the channel between the inner cylinder and the air outlet duct forms an air nozzle;

[0009] A bluff body, which is placed downstream of the inner cylinder;

[0010] A first fuel supply system, which is arranged inside the air supply duct and includes a main pipe and two groups of branch pipes connected to the downstream of the main pipe. These two groups of branch pipes include inner branch pipes entering the inner cylinder and outer branch pipes entering the outside of the inner cylinder and inside the flue gas recirculation mixing cylinder. The end of the inner branch pipe is connected to an inner branch nozzle, an ejector pipe is sleeved outside the inner branch nozzle, and the end of the outer branch pipe is connected to an outer branch nozzle;

[0011] The second fuel supply system is disposed outside the air supply duct and includes a gas collector. The gas collector is connected to a plurality of external nozzles through branch pipes, and at least a part of the external nozzles surrounds the outside of the flue gas reflux mixing cylinder; the external nozzles are divided into two groups. Among them, the injection ports of the first group of external nozzles are oriented to inject fuel towards the central direction at a first angle relative to the longitudinal axis of the air supply duct, and the injection ports of the second group of external nozzles are oriented to inject fuel towards the central direction at a second angle relative to the longitudinal axis of the air supply duct, and the first angle is not equal to the second angle.

[0012] Optionally, the inner cylinder is composed of a large-diameter straight cylinder section, a reduced-diameter section with a reduced diameter, a small-diameter throat section, and a flared section with an expanded diameter. The large end of the reduced-diameter section is connected to the straight cylinder section, the small end is connected to the small-diameter throat section, and the outlet of the small-diameter throat section is connected to the small end of the flared section.

[0013] Optionally, the outlet of the air outlet cylinder does not exceed the outlet of the reflux part.

[0014] Optionally, the position of the spray holes of the outer branch nozzles exceeds the outlet of the throat of the flue gas reflux mixing cylinder.

[0015] Optionally, the overall shape of the blunt body is wider at the front and narrower at the rear, and the wider end faces the inner cylinder.

[0016] Optionally, the blunt body is hollow in the middle and the outer wall surface is streamlined.

[0017] Optionally, the injection outlet directions of the respective ejector pipes are radially outward at an angle with the longitudinal axis of the air supply duct, and the angle range is 0° - 80°.

[0018] Optionally, the two groups of external nozzles of the second fuel supply system both surround the outside of the flue gas reflux mixing cylinder, and the second group of external nozzles is on the periphery of the first group of external nozzles, and the two groups of external nozzles are respectively circumferentially uniformly distributed outside the flue gas reflux mixing cylinder.

[0019] Optionally, the angle between the injection port of the first group of external nozzles of the second fuel supply system and the longitudinal axis of the air supply duct is 0° - 15°; the angle between the injection port of the second group of external nozzles and the longitudinal axis of the air supply duct is 5° - 20°.

[0020] In a second aspect, there is provided a working method of a gas burner system as described above, and the method includes:

[0021] Supply combustion-supporting air through the air supply duct. Most of the combustion-supporting air passes through the air nozzles, and a small part of the combustion-supporting air passes through the inner cylinder; the high-speed combustion-supporting air after passing through the air nozzles forms a low-pressure area in the flue gas reflux mixing cylinder to suck the inert combustion products in the furnace through the flue gas reflux channel, and the combustion-supporting air and the inert combustion products complete preliminary mixing at the throat of the reflux mixing cylinder;

[0022] A small portion of the required gas volume is supplied through the first fuel supply system. A part of the gas is injected into the ejector tube through the inner branch nozzles on the inner branch pipe, mixes with the combustion-supporting air inhaled from inside the inner cylinder, and burns inside the ejector tube. The flame ejects from the outlet of the ejector tube and forms a stable flame due to the obstruction of the bluff body. Another part of the gas is injected into the flue gas recirculation mixing cylinder through the outer branch nozzles on the outer branch pipe, and burns with the combustion-supporting air mixed with inert combustion products inside the diffuser section of the recirculation mixing cylinder.

[0023] A large portion of the required gas volume for the burner system is supplied through the second fuel supply system. A part of the gas is injected in the longitudinal axis direction of the gas burner system from the first group of external nozzles, and another part of the gas is injected in the longitudinal axis direction of the gas burner system from the second group of external nozzles. The high-speed gas jets formed by the injection drive the inert combustion products in the boiler furnace to follow, and complete the mixing before entering the combustion zone for combustion.

[0024] As can be seen from the above technical solutions, the embodiments of the present invention have the following advantages:

[0025] 1. The mixing of air and inert combustion products in the flue gas, and the mixing of gas and inert combustion products are completed separately before combustion, so that the flame peak value can be greatly reduced, and the emission of nitrogen oxides can be effectively reduced. Compared with the flue gas external circulation technology, the performance of the burner in terms of flame length, turndown ratio, and stability will not be sacrificed.

[0026] 2. The central flame stabilization zone adopts lean premixed combustion, which can ensure the stability of combustion while reducing the flame peak value and effectively suppressing the generation of nitrogen oxides.

[0027] 3. The present invention can further provide a turndown ratio of 10:1 to 20:1. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for describing the embodiments and the prior art will be briefly introduced below.

[0029] Figure 1 is a cross-sectional view of a gas burner system provided by an embodiment of the present invention;

[0030] Figure 2 is a perspective view of a gas burner system provided by an embodiment of the present invention;

[0031] Figure 3 is a front view of a gas burner system provided by an embodiment of the present invention;

[0032] Figure 4 is a working schematic diagram of a gas burner system provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0034] The terms "first", "second", "third", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. Additionally, the terms "inlet", "outlet", "upstream", and "downstream" are defined according to the air flow direction.

[0035] The following will be described in detail through specific embodiments respectively.

[0036] Please refer to Figures 1 to 4 , the embodiment of the present invention provides a gas burner system.

[0037] The gas burner system includes: an air supply duct 110, a flue gas recirculation mixing cylinder 140, an inner cylinder 150, a bluff body 160, a first fuel supply system 120, and a second fuel supply system 130.

[0038] The air supply duct 110 is composed of a large-diameter air duct 111, a reduced-diameter pipe 112 with a reduced diameter, and a small-diameter air outlet duct 113. The large end of the reduced-diameter pipe 112 is connected to the air duct 111, and the small end is connected to the air outlet duct 113.

[0039] The flue gas recirculation mixing cylinder 140 is composed of a reduced-diameter recirculation part 141, a small-diameter throat part 142, and an enlarged-diameter diffuser part 143. The upstream of the throat part 142 is connected to the outlet of the recirculation part 141, and the downstream is connected to the inlet of the diffuser part 143; the flue gas recirculation mixing cylinder 140 is sleeved outside the air outlet duct 113 of the air supply duct 110; the outlet of the air outlet duct 113 does not exceed the outlet of the recirculation part 141, and preferably is flush with the outlet of the recirculation part 141; the channel formed between the flue gas recirculation mixing cylinder 140 and the air outlet duct 113 of the air supply duct 110 is the flue gas recirculation channel.

[0040] The inner cylinder 150 is composed of a large-diameter straight cylinder section 151, a reduced-diameter section 152 with a shrinking diameter, a small-diameter throat section 153, and an enlarged-diameter section 154 with an expanding diameter. The large end of the reduced-diameter section 152 is connected to the straight cylinder section 151, and the small end is connected to the small-diameter throat section 153. The outlet of the small-diameter throat section 153 is connected to the small end of the enlarged-diameter section 154. The inner cylinder 150 is hollow inside and is sleeved inside the air outlet cylinder 113 of the air supply duct 110, and its outlet exceeds the throat 142 of the flue gas recirculation mixing cylinder 140. The passage between the inner cylinder 150 and the air outlet cylinder 113 forms an air nozzle.

[0041] The blunt body 160 has an overall shape that is wider at the front and narrower at the rear. The wider end faces the inner cylinder 150. It is hollow in the middle, and its outer wall surface is streamlined like an airfoil. It is placed downstream of the inner cylinder 150.

[0042] The first fuel supply system 120 is arranged inside the air supply duct 110 and is used to supply fuel to the central flame. It is composed of a main pipe 121, two groups of branch pipes, and nozzles. Three branch pipes of each of the two groups are connected downstream of the main pipe 121, that is, three inner branch pipes 122 and three outer branch pipes 124. The inner branch pipes 122 enter the inner cylinder 150, and the outer branch pipes 124 enter the space outside the inner cylinder 150 and inside the flue gas recirculation mixing cylinder 140. The ends of the two groups of branch pipes are each connected to a nozzle. The end of the inner branch pipe 122 is connected to the inner branch nozzle 123, and the end of the outer branch pipe 124 is connected to the outer branch nozzle 125. The position of the spray holes of the outer branch nozzle 125 exceeds the outlet of the throat 142 of the flue gas recirculation mixing cylinder 140, and the direction is radially outward. An ejector tube 126 is sleeved outside each inner branch nozzle 123. The side of the ejector tube 126 is provided with holes for air intake. The ejection outlet directions of the ejector tubes 126 are radially outward at a certain angle with respect to the longitudinal axis of the air supply duct 110. The angle range is 0° - 80°, preferably the angle range is 10° - 45°, and further preferably the angle range is 15° - 30°.

[0043] The second fuel supply system 130 is arranged outside the air supply duct 110 and is composed of a gas collecting bag 131, branch pipes 132, and two groups of external nozzles 133. The gas collecting bag 131 is connected to a series of external nozzles 133 arranged outside the flue gas recirculation mixing cylinder 140 through the branch pipes 132. The two groups of external nozzles are both circumferentially evenly distributed outside the flue gas recirculation mixing cylinder 140. Among them, preferably, the second group of external nozzles 133b is outside the first group of external nozzles 133a. The injection ports of the first group of external nozzles 133a are oriented to inject fuel towards the center direction at a first angle with respect to the longitudinal axis of the air supply duct 110; the injection ports of the second group of external nozzles 133b are oriented to inject fuel towards the center direction at a second angle with respect to the longitudinal axis of the air supply duct 110, and the first angle and the second angle are not equal. The first angle is, for example, between 0 - 15°, preferably between 0° - 10°, and the second angle is, for example, between 5° - 20°, preferably between 8° - 15°. Thus, the two groups of external nozzles 9133 inject towards the center direction at different angles.

[0044] The embodiment of the present invention also provides a working method for the gas burner system as described above, including:

[0045] a) Supply combustion-supporting air through the air supply duct 110. Most of the combustion-supporting air (volume ratio about 55%-80%) passes through the air nozzles, and a small part of the combustion-supporting air (volume ratio about 20%-45%) passes through the inner cylinder 150. The high-speed combustion-supporting air passing through the air nozzles will form a low-pressure area in the flue gas recirculation mixing cylinder 140 to suck the inert combustion products in the furnace through the flue gas recirculation channel. The combustion-supporting air and the inert combustion products complete preliminary mixing in the throat 142;

[0046] b) Supply a small part (volume ratio about 15%-40%) of the gas required by the gas burner system through the first fuel supply system 120. Part of the gas (10%-15%) is sprayed into the ejector pipe 126 through the inner branch nozzles 123 on the inner branch pipe 122, mixes with the combustion-supporting air sucked from inside the inner cylinder 150 and burns in the ejector pipe 126, and the flame sprays out through the outlet of the ejector pipe 126 and forms a stable flame due to the blockage of the bluff body 160. Another part of the gas (volume ratio about 10%-20%) is sprayed into the flue gas recirculation mixing cylinder 140 through the outer branch nozzles 125 on the outer branch pipe 124 and burns in the diffuser part 143 of the flue gas recirculation mixing cylinder 140 with the air mixed with inert combustion products;

[0047] c) Supply most of the gas required by the gas burner system (volume ratio about 60%-85%) through the second fuel supply system 130. Part of the gas is sprayed from the first group of external nozzles 133a at a first angle towards the main combustion area, and another part of the gas is sprayed from the second group of external nozzles 133b at a second angle towards the main combustion area. These high-speed gas jets formed by spraying will drive the inert combustion products in the furnace to follow and complete mixing with them before entering the combustion area for combustion.

[0048] The nitrogen reduction principle of the gas burner system in the embodiment of the present invention is:

[0049] After the combustion-supporting air passes through the air nozzles at high speed, a low-pressure area will be formed in the flue gas recirculation mixing cylinder 140, so as to suck the inert combustion products in the furnace through the flue gas recirculation channel. The combustion-supporting air and the inert combustion products complete preliminary mixing in the throat 142. The gas sprayed from the outer branch nozzles 125 on the outer branch pipe 124 burns with the combustion-supporting air mixed with inert combustion products in the diffuser part 143 of the flue gas recirculation mixing cylinder 140, which can greatly reduce the flame peak value in this area and effectively reduce the emission of nitrogen oxides.

[0050] The high-speed gas jet supplied by the second fuel supply system 130 can drive the inert combustion products in the furnace to follow and mix with them before entering the main combustion zone for combustion, which can greatly reduce the flame peak value in the main combustion zone and effectively reduce the emission of nitrogen oxides.

[0051] The gas supplied through the inner branch pipe 122 (with a volume ratio of about 10%-15%) is mixed and burned with the combustion-supporting air inhaled into the inner cylinder 150 (with a volume ratio of about 20%-45%). The combustion of this central flame belongs to lean-premixed combustion, so the combustion temperature is low.

[0052] In summary, the embodiments of the present invention disclose a gas burner system and its working method. From the above technical solutions, it can be seen that the embodiments of the present invention have the following advantages:

[0053] 1. Before combustion, the mixing of air and inert combustion products in the flue gas, and the mixing of gas and inert combustion products are completed respectively, so that the flame peak value can be greatly reduced, and the emission of nitrogen oxides can be effectively reduced. Compared with the flue gas external circulation technology, the performance of the burner in terms of flame length, turndown ratio and stability will not be sacrificed.

[0054] 2. The central flame stabilization zone adopts lean-premixed combustion, which can ensure the combustion stability while reducing the flame peak value and effectively suppressing the generation of nitrogen oxides.

[0055] 3. The present invention can further provide a turndown ratio of 10:1 to 20:1.

[0056] Above, the technical solutions of the present invention have been described in detail through specific embodiments. In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0057] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Those of ordinary skill in the art can modify the technical solutions recorded in the above embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas burner system, characterized in that: include: The air supply duct (110) is composed of a large-diameter air cylinder (111), a shrinking tube (112) with a shrinking diameter, and a small-diameter air outlet cylinder (113), wherein the large end of the shrinking tube (112) is connected to the air cylinder (111), and the small end is connected to the air outlet cylinder (113); The smoke return mixing cylinder (140) is composed of a return section (141) with a contracted diameter, a throat section (142) with a small diameter, and a diffuser section (143) with an enlarged diameter. The throat section (142) is connected to the outlet of the return section (141) upstream and to the inlet of the diffuser section (143) downstream. The smoke return mixing cylinder 140 is sleeved outside the air outlet cylinder (113), and the outlet of the air outlet cylinder 113 is flush with the outlet of the return section 141. The channel between the smoke return mixing cylinder (140) and the air outlet cylinder (113) constitutes a smoke return channel. The inner cylinder (150) is hollow inside and is sleeved inside the air outlet cylinder (113); the channel between the inner cylinder (150) and the air outlet cylinder (113) forms an air nozzle; A bluff body (160) disposed downstream of the inner cylinder (150); A first fuel supply system (120) is arranged inside the air supply duct (110), comprising a main pipe (121) and two groups of branch pipes connected to the downstream of the main pipe (121), the two groups of branch pipes comprising an inner branch pipe (122) entering the inner tube (150) and an outer branch pipe (124) entering the outside of the inner tube (150) and the flue gas reflux mixing tube (140), the end of the inner branch pipe (122) being connected to an inner branch nozzle (123), an ejector pipe (126) being arranged outside the inner branch nozzle (123), and the end of the outer branch pipe (124) being connected to an outer branch nozzle (125); the ejector pipe (126) has an ejection outlet direction radially outward at an angle with the longitudinal axis of the air supply duct (110), and the angle range is 10°-45°; The second fuel supply system (130) is arranged outside the air supply duct (110), and includes an air collecting bag (131). The air collecting bag (131) is connected to a plurality of external nozzles (133) via a branch pipe (132), and the external nozzles (133) at least partially surround the outside of the flue gas reflux mixing cylinder (140); the external nozzles (133) are divided into two groups, wherein the injection ports of the first group of external nozzles (133a) are oriented to inject fuel toward the center at a first angle relative to the longitudinal axis of the air supply duct (110), and the injection ports of the second group of external nozzles (133b) are oriented to inject fuel toward the center at a second angle relative to the longitudinal axis of the air supply duct (110), and the first angle is not equal to the second angle.

2. The gas burner system according to claim 1, characterized in that: The inner cylinder (150) is composed of a straight cylinder section (151) with a large diameter, a constricted section (152) with a reduced diameter, a small-diameter throat section (153) and an expanded section (154) with a widened diameter. The large end of the constricted section (152) is connected to the straight cylinder section (151), and the small end is connected to the small-diameter throat section (153). The outlet of the small-diameter throat section (153) is connected to the small end of the expanded section (154).

3. The gas burner system according to claim 1, characterized in that: The spray hole position of the external branch nozzle (125) exceeds the outlet of the throat (142) of the smoke reflow mixing cylinder (140).

4. The gas burner system according to claim 1, characterized in that: The overall shape of the bluff body (160) is wide at the front and narrow at the back, with the wide end facing the inner cylinder (150).

5. The gas burner system according to claim 4, characterized in that: The bluff body (160) is hollow and has a streamlined outer wall.

6. The gas burner system according to claim 1, characterized in that: The two groups of external nozzles (130) of the second fuel supply system (130) are both arranged around the outside of the flue gas recirculation mixing cylinder (140), and the second group of external nozzles (133b) is arranged outside the first group of external nozzles (133a). The two groups of external nozzles (130) are evenly distributed circumferentially outside the flue gas recirculation mixing cylinder (140).

7. The gas burner system according to claim 1, characterized in that: The angle between the injection ports of the first group of external nozzles (133a) of the second fuel supply system (130) and the longitudinal axis of the air supply duct (110) is 0°-15°; the angle between the injection ports of the second group of external nozzles (133b) and the longitudinal axis of the air supply duct (110) is 5°-20°.

8. A method for operating a gas burner system according to claim 1, characterized in that: The method includes: Combustion-supporting air is supplied through the air supply duct (110), most of the combustion-supporting air passes through the air nozzle, and a small part of the combustion-supporting air passes through the inner cylinder (150); the high-speed combustion-supporting air passing through the air nozzle forms a low-pressure area in the flue gas return mixing cylinder (140), and the inert combustion products in the furnace are sucked in through the flue gas return channel, and the combustion-supporting air and the inert combustion products are preliminarily mixed in the throat (142) of the return mixing cylinder (140); A small portion of the required amount of fuel gas is supplied through the first fuel supply system (120), wherein a portion of the fuel gas is sprayed into the ejector tube (126) through the inner branch nozzle (123) on the inner branch tube (122), mixed with the combustion-supporting air sucked from the inner tube (150) and burned in the ejector tube (126), and the flame is ejected through the outlet of the ejector tube (126), and a stable flame is formed due to the obstruction of the blunt body (160); wherein another portion of the fuel gas is sprayed into the flue gas reflux mixing tube (140) through the outer branch nozzle (125) on the outer branch tube (124), and burned in the diffuser (143) of the reflux mixing tube (140) with the combustion-supporting air mixed with inert combustion products; Most of the gas required by the burner system is supplied through the second fuel supply system (130), wherein a part of the gas is sprayed from the first group of external nozzles (133a) toward the longitudinal axis of the gas burner system, and another part of the gas is sprayed from the second group of external nozzles (133b) toward the longitudinal axis of the gas burner system. The high-speed gas jet formed by the spraying drives the inert combustion products in the boiler furnace to follow, and completes mixing before entering the combustion zone for combustion.

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