CN112413587A

CN112413587A - Double-venturi flue gas internal circulation low-nitrogen combustion device and combustion method

Info

Publication number: CN112413587A
Application number: CN202011446369.7A
Authority: CN
Inventors: 马子安; 刘冰
Original assignee: Shanghai Bonasen Environmental Technology Co ltd
Current assignee: Shanghai Wisebond Technology Co ltd
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-02-26

Abstract

The invention discloses a double-venturi flue gas internal circulation low-nitrogen combustion device and a combustion method. The device comprises a multi-layer throat, wherein a smoke internal circulation suction inlet is formed in the outer wall of the multi-layer throat, a smoke internal circulation device is arranged in the multi-layer throat cavity and is in butt joint with the smoke internal circulation suction inlet, a high-speed mixed gas channel is arranged at the outlet of the multi-layer throat, a combustion-supporting air channel and a fuel gas channel are arranged in the multi-layer throat cavity, and a spray gun is arranged at the front end of the fuel gas channel and extends out of the outlet of the multi-layer throat. Therefore, the smoke internal circulation type low-nitrogen combustion device which sucks and rolls peripheral smoke near the throat opening into the inside/outside air feeding area of the throat opening and participates in the combustion function after being mixed with combustion-supporting air is realized, low-nitrogen combustion can be realized, and the generation of NOx is reduced.

Description

Double-venturi flue gas internal circulation low-nitrogen combustion device and combustion method

Technical Field

The invention relates to the field of gas combustion, in particular to a double-venturi flue gas internal circulation low-nitrogen combustion device and a combustion method.

Background

Nitrogen oxides (NOx) contained in exhaust gas discharged from boilers using fossil resources such as natural gas, coal, petroleum and the like as fuel are recognized as atmospheric pollutants, and the functional departments set increasingly strict exhaust emission standards for the purpose of strict control, and now, the standard requirement that the NOx emission of natural gas must be reduced to below 60mg, even 30mg/Nm3 is proposed.

The existing industry generally adopts a method of matching a low-nitrogen combustion technical device on the existing boiler and carrying out low-nitrogen standard-reaching transformation, and finds that the generation amount of NOx can be remarkably reduced by properly reducing the flame temperature in the fuel combustion process and the oxygen content of combustion gas. For a gas boiler taking high-calorific-value gas such as natural gas and the like as fuel, a low-nitrogen route comprising a low-nitrogen burner and flue gas external circulation is adopted at present, wherein the flue gas external circulation is realized by leading part of flue gas to be discharged, which is relatively low in temperature and oxygen content, from the tail of the boiler to return to a hearth for mixed combustion.

However, in practice, it is found that when the boiler adopts flue gas external circulation, external circulation components including a flue gas circulation fan, a flue gas circulation pipeline and the like must be added to the boiler, so that part of the flue gas to be discharged outside can be guided and conveyed to specific positions of a combustor and related components of the boiler, the arrangement is troublesome, the modification cost is high, in addition, due to the fact that temperature difference exists between the lower-temperature flue gas and the normal-temperature combustion air in the working process, condensed water can be generated during mixing, besides extra energy loss is needed when water evaporation exists, surrounding components can be corroded, the defects of large workload of daily maintenance and high daily use cost exist, and therefore the boiler is not ideal from the aspects of practicability and economy.

Disclosure of Invention

The invention aims to provide a double-venturi flue gas internal circulation low-nitrogen combustion device and a combustion method, which can reduce the emission of easily-polluted nitrogen oxides.

In order to solve the above technical problem, according to a first aspect of the present invention, there is provided a dual venturi flue gas internal circulation low nitrogen combustion apparatus comprising:

the multi-layer throat comprises a plurality of layers of throats, wherein the outer wall of each throat is provided with a smoke internal circulation suction inlet, a smoke internal circulation device is arranged in each throat cavity, the smoke internal circulation device is in butt joint with the smoke internal circulation suction inlet, the outlet of each throat is a high-speed mixed gas channel, a combustion-supporting air channel and a gas channel are arranged in each throat cavity, and the front end of each gas channel is a spray gun and extends out of the outlet of each throat.

Optionally, the gas channel further includes a gas pipe and a co-junction gas inlet end connected to each other, the spray gun includes a central spray gun and a peripheral spray gun, and the co-junction gas inlet end is connected to the central spray gun and the peripheral spray gun.

Optionally, the multi-layer laryngeal inlet includes an inner laryngeal inlet at the front end of the laryngeal inlet, a middle laryngeal inlet located at the front end of the laryngeal inlet, and an outer laryngeal inlet located at the tail end of the laryngeal inlet.

Optionally, the main body of the inner throat is cylindrical, and the front end part of the main body is provided with an inner end surface of the inner throat; the main body of the middle throat is in a cylindrical shape with a telescopic structure, and the front end part is provided with an inner end surface of the middle throat; the main body of the outer throat is cylindrical, the front end part of the main body is provided with an outer throat contraction inner end surface, and the outer wall of the main body of the outer throat is provided with the smoke internal circulation suction inlet; the middle throat is arranged between the inner throat and the outer throat in a matching mode.

Optionally, a region between the outer wall of the main body of the outer throat and the gas channel is used as a combustion-supporting air channel.

Optionally, the high-speed gas mixture channel includes a first high-speed gas mixture channel formed by a gap between the inner end surface of the outer throat and the inner end surface of the middle throat, and a second high-speed gas mixture channel formed by a gap between the inner end surface of the middle throat and the inner end surface of the inner throat.

Optionally, be provided with the flame holder on the interior throat internal end face, the flame holder main part is discoid, be equipped with flame stabilizing air passageway and cooling air through-hole on the flame holder.

Optionally, the flue gas internal circulation device is fixedly arranged on the outer throat, and includes: the main body is a flue gas channel formed by the cross-connection and interconnection of a horizontal flue gas inlet ring and a longitudinal flue gas outlet ring, and a Venturi combustion-supporting air pipe formed by the coaxial interconnection of a reducing pipe and a straight-through pipe which is fixedly inserted on the flue gas channel.

Optionally, the flue gas passageway cross-section is the L type, includes two upper and lower ring plates and constitutes, and two upper and lower ring plates are the shrink form.

According to a second aspect of the present invention, there is provided a combustion method comprising:

the spray gun sprays fuel gas, and the combustion air channel sprays combustion air;

the smoke internal circulation suction inlet generates negative pressure, and the smoke at the periphery of the suction roll enters the multilayer laryngeal inlet cavity;

the high-speed mixed gas channel generates negative pressure, and the smoke around the suction roll flows back to the nozzle;

the combustion air in the combustion air channel is respectively mixed with peripheral flue gas sucked and coiled in the forward process, and high-speed mixed flue gas is divergently sprayed at the outlet of the multi-layer throat to form combustion gas with low oxygen content, and the combustion gas enters the hearth to participate in low-nitrogen combustion.

The invention provides a double-venturi smoke internal circulation low-nitrogen combustion device and a combustion method, wherein the device comprises a multi-layer throat, a smoke internal circulation suction inlet is formed in the outer wall of the multi-layer throat, a smoke internal circulation device is arranged in the multi-layer throat cavity and is in butt joint with the smoke internal circulation suction inlet, a high-speed mixed gas channel is arranged at the outlet of the multi-layer throat, a combustion-supporting air channel and a fuel gas channel are arranged in the multi-layer throat cavity, and a spray gun is arranged at the front end of the fuel gas channel and extends out of the outlet of the multi-layer throat. Therefore, the smoke internal circulation type low-nitrogen combustion device which sucks and rolls peripheral smoke near the throat opening into the inside/outside air feeding area of the throat opening and participates in the combustion function after being mixed with combustion-supporting air is realized, low-nitrogen combustion can be realized, and the generation of NOx is reduced.

Drawings

FIG. 1 is a first schematic diagram of a dual venturi flue gas internal circulation low nitrogen combustion device in accordance with an embodiment of the present invention;

FIG. 2 is a second cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a schematic view of an internal circulation device for flue gas according to an embodiment of the present invention;

FIG. 4 is a schematic view taken along the direction A in FIG. 3;

FIG. 5 is a schematic illustration of a combustion process according to an embodiment of the present invention.

Detailed Description

The dual venturi internal flue gas recirculation low nitrogen combustion apparatus and method of the present invention will now be described in greater detail with reference to the schematic drawings wherein preferred embodiments of the invention are shown, it being understood that persons skilled in the art may modify the invention herein described while still achieving the advantageous effects of the invention. Accordingly, the following description should be construed as broadly as possible to those skilled in the art and not as limiting the invention.

The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

In the following description, it should be understood that references to "inner" and "outer" in various structures may be made based on the drawings.

Example 1

The embodiment 1 provides a dual venturi flue gas internal circulation low nitrogen combustion device, and the embodiment described below by referring to the drawings is exemplary only for the purpose of explaining the present invention and is not to be construed as limiting the present invention. As shown in fig. 1, the dual venturi flue gas internal circulation low-nitrogen combustion device comprises:

the multi-layer throat comprises multiple layers of throats, wherein smoke internal circulation suction inlets 132 are formed in the outer walls of the multiple layers of throats, smoke internal circulation devices 6 are arranged in cavities of the multiple layers of throats, the smoke internal circulation devices 6 are in butt joint with the smoke internal circulation suction inlets 132, high-speed mixed gas channels are arranged at the outlets of the multiple layers of throats, combustion-supporting air channels 4 and gas channels 3 are arranged in the cavities of the multiple layers of throats, and spray guns 2 are arranged at the front ends of the gas channels 3 and extend out of the outlets of the multiple layers of throats.

The embodiment of the invention relates to a smoke internal circulation type low-nitrogen combustion device which has the functions of sucking peripheral smoke near a throat into an air supply area inside/outside the throat, mixing the smoke with combustion-supporting air and then participating in combustion.

Example 2

This embodiment 2 provides a dual venturi flue gas internal circulation low-nitrogen combustion device, which may be further optimized or improved on the basis of embodiment 1, and the embodiment described below with reference to the drawings is exemplary only for the purpose of illustrating the present invention and is not to be construed as limiting the present invention. With continuing reference to fig. 1-5, embodiment 2 includes:

the gas channel 3 further comprises a gas pipe 31 and a co-junction gas inlet end which are connected, the spray gun 2 comprises a central spray gun 21 and a peripheral spray gun 22, and the co-junction gas inlet end is connected with the central spray gun and the peripheral spray gun.

The co-junction air inlet end may comprise a plurality of "L" shaped structures, one end connected together and connected to the gas pipe 31 and the other end connected to the spray paint 2.

The spray holes of the peripheral spray gun 22 can be arranged according to requirements, and can be used for axial spraying or radial spraying.

The gas pipe 31 can be filled by a gas pipe communicated with a gas supply main pipe.

The multilayer laryngeal inlet comprises an inner laryngeal inlet 11 at the front end of the laryngeal inlet, a middle laryngeal inlet 12 positioned at the front end of the laryngeal inlet and an outer laryngeal inlet 13 positioned at the tail end of the laryngeal inlet. Referring to fig. 5, the outer throat 13 is adjacent the furnace wall 7.

In this embodiment, the main body of the inner throat 11 is cylindrical, and the front end thereof is provided with an inner throat inner end surface 111; the main body of the middle throat 12 is in a shape of a cylinder with a telescopic cylinder, and the front end part is provided with an inner end surface 121 of the middle throat; the main body of the outer throat 13 is cylindrical, the front end part of the main body is provided with an outer throat contraction inner end surface 131, and the outer wall of the main body of the outer throat 13 is provided with the smoke internal circulation suction inlet 132; the middle throat 12 is arranged between the inner throat 11 and the outer throat 13 in a matching manner.

Preferably, the inner throat 11, the middle throat 12 and the outer throat 13 are coaxially arranged.

The gas channel 3 is fixedly arranged on the axis position of the multi-layer throat.

The area between the outer wall of the main body of the outer throat 13 and the gas channel 3 serves as a combustion-supporting air channel 4, i.e. is filled by a throat cavity ring 41 located at the periphery of the gas pipe 31.

A flame stabilizing device 5 is arranged at the front end part of the inner throat 11, the main body of the flame stabilizing device 5 is disc-shaped, and a flame stabilizing air channel 51 and a cooling air through hole 52 are arranged on the flame stabilizing device 5; the flame stabilizing air passage 51 is in a straight hole shape or a rotational flow shape with a certain inclination angle. The flame holding air passage 51 and the cooling air through holes 52 may be uniformly arranged.

The high-speed mixed gas channel 8 includes a first high-speed mixed gas channel 81 formed by a gap between the outer throat inner end surface 131 and the inner throat inner end surface 121, and a second high-speed mixed gas channel 82 formed by a gap between the inner throat inner end surface 121 and the inner throat inner end surface 111.

Further, the inner throat end surface 121 and the inner throat end surface 131 may be configured to be telescopic, so that the sizes of the first high-speed mixed gas channel 81 and the second high-speed mixed gas channel 82 can be adjusted.

The smoke internal circulation device 6 is fixedly arranged on the external throat 13, please refer to fig. 3 and fig. 4, wherein fig. 3 is a partial sectional view along B-B of fig. 1, and includes: the main body is a flue gas channel 61 formed by the connection and interconnection of a horizontal flue gas inlet ring 611 and a longitudinal flue gas outlet ring 612, and a Venturi combustion-supporting air pipe 62 formed by the coaxial interconnection of a reducing pipe 621 and a straight-through pipe 622 which is fixedly inserted in the flue gas channel 61.

Preferably, the section of the flue gas channel 61 is L-shaped, and comprises an upper circular plate 631 and a lower circular plate 632, and the upper circular plate 631 and the lower circular plate 632 are in a contracted shape.

The straight-through pipe 622 can be arranged on the wall of the interconnecting and connecting cavity of the horizontal flue gas inlet ring 611 and the longitudinal flue gas outlet ring 612.

Example 3

This example 3 provides a combustion method that may be based on the apparatus described in any of examples 1 or 2, or may not be limited to such an apparatus, and the examples described below are exemplary and are intended to be illustrative only and should not be construed as limiting the invention. The present embodiment 3 includes:

a method of combustion, comprising:

The embodiment can obviously reduce the oxygen content in the gas participating in combustion, is favorable for the uniform distribution of combustion flame in the hearth and the generation probability of reducing the local high-temperature point, thereby ensuring the low-oxygen and low-nitrogen combustion for effectively inhibiting the generation amount of NOx and providing technical support for the standard-reaching transformation of the boiler.

Example 4

This example 4 provides a combustion process that may be optimized or modified based on example 3, which is described below for purposes of illustration only and is not to be construed as a limitation of the present invention. Referring to fig. 1-5, the present embodiment 3 includes:

when in work, the fuel gas is fed into each spray gun 2 through the fuel gas pipe 31 and is supplied to each spray gun; combustion-supporting air enters from the tail end of the outer throat 13 and flows forwards in the combustion-supporting air channel 4, most of the combustion-supporting air gradually accelerates forwards at the periphery of the flue gas internal circulation device 6, a small part of the combustion-supporting air enters in alignment with the port of the reducing pipe 621 of the Venturi combustion-supporting air pipe 62 in a clockwise direction, is accelerated by the reducing pipe 621 into high-speed airflow and then flows out through the straight pipe 622 to enter the longitudinal flue gas outlet ring 612, negative pressure capable of generating suction force on the horizontal flue gas inlet ring 611 is generated in the longitudinal flue gas outlet ring 612, the flue gas around the outer throat 13 is sucked and coiled into the longitudinal flue gas outlet ring 612 in a clockwise direction, is mixed with the high-speed combustion-supporting air from the straight pipe 622 and then enters the combustion-supporting air channel 4, and is converged with most of the combustion-supporting air gradually accelerated to form a primary mixed flue gas flow with a certain flow.

Most of the combustion air flows through the periphery of the flue gas internal circulation device 6, namely after being contracted and guided by the lower contraction ring plate 632, the air is rapidly accelerated and axially flows out at high speed at the outlet end face of the lower contraction ring plate 632, so that negative pressure is formed on the longitudinal flue gas outlet ring channel 612, and the flue gas outside the outer throat 13 is sucked and mixed with the flue gas.

The primary mixed flue gas flow with a certain flow velocity continuously flows forwards, most of the primary mixed flue gas flow advances into the section of the middle throat 12, the small part of the primary mixed flue gas flow advances into the first high-speed mixed gas channel 81 and then is ejected at a high speed, a negative pressure area is formed near the nozzle, and therefore flue gas on the periphery of the outer throat 13 of the combustion device is sucked, entrained and flows back to the position near the front end surface 131 of the outer throat and is mixed with the small part of primary mixed flue gas flow ejected from the first high-speed mixed gas channel 81, and low-oxygen and low-nitrogen combustion is carried out. Most of the primary mixed flue gas flow which advances into the section of the middle throat 12 further accelerates and advances when flowing through the telescopic cylinder of the middle throat 12, wherein a part of the primary mixed flue gas flow advances into the second high-speed mixed gas channel 82 and then is ejected at a high speed, a negative pressure zone is formed near the nozzle, so that the flue gas on the periphery of the middle throat 12 of the combustion device is sucked, curled and flows back to the vicinity of the front end surface 121 of the middle throat, and is mixed with the primary mixed flue gas flow ejected from the second high-speed mixed gas channel 82 to perform low-oxygen and low-nitrogen combustion; the other part of the smoke is continuously moved to the inner side of the flame stabilizing device 5 to be blocked and limited after moving into the section of the inner throat 11, and is sprayed to form mixed smoke flow when flowing through the flame stabilizing air channel 51 with smaller flow area and the cooling air through hole 52; because the outlet area of the flame holding device 5 is large, but the air quantity passing through the flame holding device 5 is small, and the high-speed air flowing out of the second high-speed mixer channel 82 at the periphery of the flame holding device 5 forms a negative pressure area with stronger roll suction capability at the outlet of the flame holding device 5, so that the flue gas and the mixed gas at the periphery of the inner throat 11 are sucked, rolled and returned to the vicinity of the front end surface 111 of the inner throat and mixed with the other part of primary mixed flue gas flow ejected from the flame holding device 5, and then low-oxygen and low-nitrogen combustion is carried out.

The combustion air entering the combustion air channel 4 is sucked and coiled for many times on the smoke internal circulation device 6, the first high-speed mixed gas channel 81, the second high-speed mixed gas channel 82 and the flame stabilizing device 5 arranged on the front end surface 111 of the inner throat respectively to be mixed with the oxygen-poor smoke at different positions of the throat area of the combustion device in the advancing process, and the high-speed mixed smoke is divergently sprayed at different positions to enter the hearth, so that the oxygen content in the combustion gas is remarkably reduced, the uniform distribution of combustion flame in the hearth is facilitated, the generation probability of local high-temperature points is reduced, the low-nitrogen combustion capable of effectively inhibiting the generation amount of NOx is ensured, and the technical guarantee is provided for the standard improvement of boilers.

Therefore, the technical scheme of the invention has the advantages of reasonable and scientific structure, reliable work and high automation degree, has the function of enabling a large amount of oxygen-poor flue gas to flow back to the inner and outer areas of the throat of the burner, be sprayed into the furnace in multiple directions after being mixed and participate in the internal circulation of the flue gas of the oxygen-poor low-nitrogen combustion, can achieve the substantial effect of reducing the emission of NOx through the internal circulation of the flue gas, fills the blank of the industry, and has strong practicability and wide market application prospect.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A dual venturi flue gas internal circulation low-nitrogen combustion device, comprising:

2. The dual venturi intraflue gas recirculation low nitrogen combustion device of claim 1, wherein said gas duct further comprises a connected gas pipe and a common inlet end, said lances comprising a central lance and a peripheral lance, said common inlet end connecting said central lance and said peripheral lance.

3. The dual venturi smoke internal circulation low nitrogen combustion device of claim 2, wherein said multi-level throats comprise an inner throat at a front end of the throat, a middle throat at a front end of the throat and an outer throat at a rear end of the throat.

4. The dual venturi flue gas internal circulation low nitrogen combustion device of claim 3, wherein the main body of the inner throat is cylindrical, and the front end portion is provided with an inner throat inner end surface; the main body of the middle throat is in a cylindrical shape with a telescopic structure, and the front end part is provided with an inner end surface of the middle throat; the main body of the outer throat is cylindrical, the front end part of the main body is provided with an outer throat contraction inner end surface, and the outer wall of the main body of the outer throat is provided with the smoke internal circulation suction inlet; the middle throat is arranged between the inner throat and the outer throat in a matching mode.

5. The dual venturi smoke internal circulation low nitrogen combustion device of claim 4, wherein a region between the outer wall of the main body of the outer throat and the gas channel serves as a combustion supporting air channel.

6. The dual venturi flue gas internal circulation low nitrogen combustion device of claim 4, wherein said high velocity mixture passage comprises a first high velocity mixture passage formed by a gap between said outer throat internal end face and said middle throat internal end face, and a second high velocity mixture passage formed by a gap between said middle throat internal end face and said inner throat internal end face.

7. The dual-venturi internal flue gas circulation low-nitrogen combustion device as claimed in claim 4, wherein a flame holder is disposed on the inner end surface of the inner throat, the main body of the flame holder is disc-shaped, and the flame holder is provided with a flame holding air passage and a cooling air through hole.

8. The dual venturi internal flue gas recirculation low nitrogen combustion device of claim 4, wherein said internal flue gas recirculation device is fixed to the external throat, comprising: the main body is a flue gas channel formed by the cross-connection and interconnection of a horizontal flue gas inlet ring and a longitudinal flue gas outlet ring, and a Venturi combustion-supporting air pipe formed by the coaxial interconnection of a reducing pipe and a straight-through pipe which is fixedly inserted on the flue gas channel.

9. The dual venturi internal flue gas circulation low nitrogen combustion device of claim 8, wherein said flue gas channel is L-shaped in cross section and comprises an upper circular plate and a lower circular plate, wherein the upper circular plate and the lower circular plate are constricted.

10. A method of combustion, comprising: