A gas low-nitrogen combustor for a rotary kiln

Abstract

The present application relates to rotary kiln technical field, and disclose a kind of gas low nitrogen combustor for rotary kiln, including gas cavity, air distribution body, lengthening cylinder and flame stabilizer tube, the ignition gun and primary gas jet are arranged in the gas cavity, the ignition gun and primary gas jet are all extended to flame stabilizer tube, the inside of flame stabilizer tube is provided with primary air swirler, partition cylinder and secondary air swirler, and partition cylinder separates primary swirler and secondary air swirler, secondary and tertiary gas jet are provided in the flame stabilizer tube, secondary and tertiary gas jet are provided with secondary and tertiary gas spray head, primary gas jet is provided on the primary gas jet, secondary gas injection gun, tertiary gas injection gun and primary gas injection gun are provided in the gas cavity, significantly reduce the generation of nitrogen oxides, combustion is more stable, emission is lower, using air staging and gas staging principle, air gas mixing is more uniform, the effect of reducing NOx emission.

Description

Technical Field

[0001] This invention relates to the field of rotary kiln technology, specifically to a low-NOx burner for rotary kilns. Background Technology

[0002] Currently, with the increasing emphasis on environmental protection by national and local governments, taking natural gas as a fuel, the industrial emission standards for nitrogen oxides from rotary kiln enterprises require a limit of less than 100 mg / m3 (the converted value when the oxygen concentration in the flue gas is 8%). Due to the special nature of the rotary kiln heating process, a large amount of air is drawn in from the environment during the heating process (called "secondary air"), resulting in a high oxygen content in the flue gas at the kiln tail (up to 16% or more). After conversion based on an 8% oxygen content, the converted value of nitrogen oxides reaches more than 150-200 mg / m3, far exceeding the limits set by national and local nitrogen oxide emission standards.

[0003] Currently, the front-end treatment method is to use an ultra-low NOx emission environmentally friendly burner alone. The burner's own NOx reduction technology directly reduces NOx emissions to below 100mg / m3 (the equivalent value when the flue gas oxygen concentration is 8%). If it is necessary to further reduce NOx emission levels, the technical route of "ultra-low NOx emission environmentally friendly burner + FGR (flue gas external circulation technology for NOx reduction)" is used. However, since the flue gas outlet is a long distance away from the burner (50-100 meters), the investment cost of FGR technology is relatively high.

[0004] In conventional rotary kiln burners, the ignition gun is installed on the rear cover plate and inserted into the gas cyclone separator, which is then fixed in place. The flame detector is mounted on the rear cover plate, which is then connected to the gas chamber via a flange and secured with bolts. The gas cyclone separator is fixed in place on the gas chamber, which is then connected to the air distribution unit via a flange and secured with bolts. The air distribution unit is connected to the extension cylinder via a flange and secured with bolts. After the gas enters the gas chamber, it generates a rotating gas flow through the gas cyclone separator. Air enters the air distribution unit and generates a rotating air flow through the air cyclone separator. The air and the rotating gas flow mix in the extension cylinder before being ejected. This structure can only ensure complete combustion of the fuel, but it results in high nitrogen oxide emissions, which fail to meet standards.

[0005] Therefore, a low-NOx gas burner for rotary kilns is proposed to solve the problems mentioned above. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a low-NOx burner for rotary kilns, which has advantages such as stable combustion, strong flame rigidity, uniform mixing, no obvious flame peak gradient, and lower NOx emissions. It solves the problem of NOx emission standards not being met in existing methods that use ultra-low NOx emission environmentally friendly burners alone, and also solves the problem of high technical investment costs in the ultra-low NOx emission environmentally friendly burner + FGR method.

[0008] (II) Technical Solution

[0009] To achieve the aforementioned goals of stable combustion, strong flame rigidity, uniform mixing, no significant flame peak gradient, and lower nitrogen oxide emissions, this invention provides the following technical solution: a low-NOx burner for rotary kilns, comprising a gas chamber, an air distribution body, an extension cylinder, and a flame stabilizer. The gas chamber and air distribution body, the air distribution body and the extension cylinder, and the extension cylinder and the flame stabilizer are all connected by flanges. The left side of the gas chamber is connected to a rear cover plate via a flange, and a flame detector is installed inside the rear cover plate. A flame detector is installed inside the gas chamber. The device includes an ignition gun and a primary gas nozzle, both of which extend into a flame stabilizer. The flame stabilizer contains a primary air vortex generator, a baffle, and a secondary air vortex generator, with the baffle separating the primary and secondary air vortex generators. The flame stabilizer also contains secondary and tertiary gas nozzles, each equipped with a secondary and tertiary gas nozzle head, and a primary gas nozzle head. The gas chamber contains a secondary gas nozzle, a tertiary gas nozzle, and a primary gas nozzle.

[0010] Preferably, the air passage of the burner is divided into a primary air passage, a secondary air passage, and a tertiary air passage using the principle of air grading.

[0011] Preferably, utilizing the principle of gas grading, the gas chamber consists of two parts: a primary gas chamber and a secondary gas chamber, ultimately forming a primary gas channel, a secondary gas channel, and a tertiary gas channel. Each gas chamber has an external gas interface that connects to a corresponding gas pipeline, and a manually adjustable valve is installed on the gas pipeline. The primary gas is ejected from the primary gas chamber through a primary annular group of annular spray guns; this portion of gas is called primary gas. The secondary gas is ejected from the secondary gas chamber through a secondary gas spray gun group and a tertiary annular spray gun group; this portion of gas is called secondary gas and tertiary gas.

[0012] Preferably, the primary gas spray gun group, the secondary gas spray gun group, and the tertiary gas spray gun group are distributed in different air channels, and when the gas is sprayed out, it mixes with the air in the area in different directions, at different angles, and to different degrees.

[0013] Preferably, the burner head is designed to be elongated, so that the burner head extends into the rotary kiln and over the material discharge port, so that the combustion flame is distributed in the effective area. The part of the burner that extends into the kiln is made of heat-resistant stainless steel to meet the service life requirements under high temperature conditions.

[0014] (III) Beneficial Effects

[0015] Compared with the prior art, the present invention provides a low-NOx burner for rotary kilns, which has the following advantages:

[0016] This rotary kiln uses a low-NOx burner with three sets of gas injection guns that spray gas into the near, middle, and far gas distribution areas. The gas chamber is equipped with two interfaces, one for primary gas and one for secondary gas, which are connected to manual regulating valves on the primary and secondary gas pipelines. The distribution ratio of the primary and secondary gas can be adjusted manually to control the NOx emission level. This achieves ultra-low NOx emissions from industrial gas in the rotary kiln combustion process, effectively and significantly reducing the formation of nitrogen oxides, resulting in more stable combustion and lower emissions. By utilizing the principles of air staging and gas staging, the air and gas mixture is more uniform and thorough, leading to a more significant reduction in NOx emissions. Attached Figure Description

[0017] Figure 1 This is a cross-sectional structural diagram of a low-NOx gas burner for a rotary kiln proposed in this invention;

[0018] Figure 2 This is a cross-sectional structural diagram of a conventional rotary kiln gas burner.

[0019] Figure 3 This is a schematic diagram of the cross-sectional structure of a low-NOx gas burner for a rotary kiln proposed in this invention.

[0020] Figure 4 This is a cross-sectional view of the primary gas nozzle and the secondary gas nozzle of a low-NOx gas burner for a rotary kiln proposed in this invention.

[0021] Figure 5 This is a schematic cross-sectional view of the tertiary gas nozzle of a low-NOx gas burner for a rotary kiln proposed in this invention.

[0022] Figure 6 This is a three-dimensional structural diagram of the flame stabilizer tube for a low-NOx gas burner used in a rotary kiln, as proposed in this invention.

[0023] In the diagram: 1. Ignition gun, 2. Flame detector probe, 3. Rear cover plate, 4. Gas chamber, 5. Air distribution body, 6. Primary gas nozzle, 7. Extension tube, 8. Primary air cyclone separator, 9. Divider, 10. Secondary air cyclone separator, 11. Secondary and tertiary gas nozzles, 12. Flame stabilizer tube, 13. Secondary and tertiary gas nozzles, 14. Primary gas nozzle, 15. Secondary gas nozzle, 16. Tertiary gas nozzle, 17. Primary gas nozzle. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] exist Figure 1 In this process, the ignition gun 1 is installed on the rear cover plate 3, inserted into the primary air cyclone separator 8, and the primary air cyclone separator 8 is positioned and securely fixed; the flame detector 2 is installed on the rear cover plate 3, and the rear cover plate 3 is connected to the gas chamber 4 via a flange and tightened with bolts; the gas chamber 4 consists of a primary gas chamber and a secondary gas chamber. The primary gas chamber is connected to the primary gas nozzle 6 and sprays out from the nozzle, which is called primary gas; the secondary gas chamber is connected to the secondary and tertiary gas nozzles 11 and sprays out from the nozzle, which are called secondary gas and tertiary gas, respectively; the above three sets of nozzles are arranged in a concentric ring; each set of nozzles... The head is connected to its corresponding primary gas nozzle 14, secondary and tertiary gas nozzles 13 by threads, and there are fixing screws on the side of the nozzle to fix the nozzle orientation; the primary air cyclone 8 is installed inside the partition cylinder 9 and fixed in position with bolts and nuts; the secondary air cyclone 10 is installed outside the partition cylinder 9 and fixed in position with bolts and nuts; the secondary and tertiary gas nozzles 11 pass through the secondary air cyclone 10, the air distribution body 5 and the tensioning cylinder 7 are connected by a mounting flange and fastened with bolts and nuts; the other end of the extension cylinder 7 is connected to the flame stabilizer cylinder 12 by a flange and fastened with bolts and nuts.

[0026] exist Figure 1 In the middle, the gas chamber 4 is equipped with two interfaces, one for primary gas and one for secondary gas, which are connected to the manual regulating valves on the primary and secondary gas pipelines. The distribution ratio of primary and secondary gas can be manually adjusted, and the NOx emission can be controlled by controlling the combustion amount of primary and secondary gas respectively.

[0027] exist Figure 3In the combustion chamber, air entering the air distribution body 5 is divided into primary air passage, secondary air passage, and tertiary air passage; gas entering the combustion chamber 4 is divided into two sets of passages, namely primary gas, secondary gas, and tertiary gas. Primary gas is ejected through primary gas nozzle 17, while secondary and tertiary gas are ejected through secondary gas nozzle 15 and tertiary gas nozzle 16. Secondary gas nozzle 15 and tertiary gas nozzle 16 share the same set of annular gas nozzles, with different nozzles evenly spaced to occupy the circumferential position. Each set of gas nozzles extends into the air passages of each stage. Ignition gun 1 is located on the side of the burner and is used to ignite primary gas nozzle 17.

[0028] exist Figure 4 In the diagram, the arrows indicate the injection directions of the primary and secondary combustion gases. After entering the nozzle along the axis, the primary and secondary combustion gases are ejected from the radially perforated positions, spraying perpendicularly to the axis at 90°, forming a uniformly dispersed circumferential state. The primary combustion gas generates a near-end combustion zone after contacting the adjacent air, while the secondary combustion gas generates an intermediate combustion zone after contacting the adjacent air.

[0029] exist Figure 5 In the diagram, the arrow points to the direction of the tertiary gas injection. After entering the nozzle along the axis, the tertiary gas continues to be ejected along the axis, directly towards the far end. This part of the gas comes into contact with the adjacent air to create a far-end combustion zone.

[0030] exist Figure 6 In the middle, the flame stabilizer 12 is composed of a cylinder, a constriction, a flue gas internal circulation inlet, and a flue gas internal circulation outlet. The constriction causes the flame to produce a converging effect, improving the flame rigidity and length. The flue gas internal circulation inlet and the flue gas internal circulation outlet increase the amount of flue gas introduced into the burner, which has a significant effect on reducing the oxygen content of the combustion air and reducing nitrogen oxide emissions.

[0031] In summary, this rotary kiln low-NOx burner features a single air inlet divided into three channels and two gas channels. It employs a central spray gun + annular spray gun structure. The annular spray gun uses nozzles with different injection directions, spaced out. The three gas spray guns have different injection directions: the primary gas spray gun 17 injects radially in all directions, the secondary gas spray gun 15 injects radially in all directions, and the tertiary gas spray gun 16 injects directly. These three sets of gas spray guns inject gas into the near, middle, and far gas distribution areas. The gas chamber 4 has two interfaces, one for primary gas and one for secondary gas, connected to manual regulating valves on the primary and secondary gas pipelines. The distribution ratio of the primary and secondary gas can be manually adjusted to control NOx emissions. This achieves ultra-low NOx emissions from the industrial gas combustion process in the rotary kiln, effectively and significantly reducing nitrogen oxide formation, resulting in more stable combustion and lower emissions. Utilizing the principles of air and gas staging, the air-gas mixture is more uniform and thorough, leading to a more significant reduction in NOx emissions.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-NOx gas burner for a rotary kiln, comprising a gas chamber (4), an air distribution body (5), an extended cylinder (7), and a flame stabilizer (12), characterized in that: The gas chamber (4) and the air distribution body (5), the air distribution body (5) and the extension tube (7), and the extension tube (7) and the flame stabilizer tube (12) are all connected by flanges. The left side of the gas chamber (4) is connected by a rear cover plate (3) through a flange. A flame detector (2) is installed inside the rear cover plate (3). An ignition gun (1) and a primary gas nozzle (6) are provided inside the gas chamber (4), and both the ignition gun (1) and the primary gas nozzle (6) extend into the flame stabilizer (12). The flame stabilizer tube (12) is provided with secondary and tertiary gas nozzles (11), and the secondary and tertiary gas nozzles (11) are provided with secondary and tertiary gas nozzles (13), and the primary gas nozzle (6) is provided with a primary gas nozzle (14). The gas chamber (4) is equipped with a secondary gas spray gun (15), a tertiary gas spray gun (16) and a primary gas spray gun (17); After entering the air distribution body (5), the air is divided into a primary air channel, a secondary air channel, and a tertiary air channel; after entering the gas chamber (4), the gas is divided into two groups of channels and into primary gas, secondary gas, and tertiary gas. The primary gas is ejected through the primary gas nozzle (17), and the secondary and tertiary gas are ejected through the secondary gas nozzle (15) and the tertiary gas nozzle (16). The secondary gas nozzle (15) and the tertiary gas nozzle (16) share the same set of gas annular nozzles. After the primary and secondary combustion gases enter the nozzle along the axis, they are ejected from the radially perforated position, spraying perpendicularly to the axis at 90°, forming a uniformly dispersed circumferential state; after the tertiary combustion gases enter the nozzle along the axis, they are still ejected along the axis, directly spraying towards the far end. After the primary combustion gases come into contact with the adjacent air, a near-end combustion zone is generated, and after the secondary combustion gases come into contact with the adjacent air, an intermediate combustion zone is generated. The flame stabilizer (12) consists of a cylinder, a constriction, a flue gas internal circulation inlet and a flue gas internal circulation inlet. The constriction causes the flame to have a converging effect, which improves the flame rigidity and length. The flame stabilizer (12) is provided with a primary air vortex (8), a partition (9) and a secondary air vortex (10) inside, and the partition (9) separates the primary air vortex (8) and the secondary air vortex (10).

Images