CN116379431A

CN116379431A - Four-in-one low-nitrogen combustor

Info

Publication number: CN116379431A
Application number: CN202310329704.2A
Authority: CN
Inventors: 黄艳; 吝华陆; 胡钰; 张雷
Original assignee: Wuhan Mingzheng Power Engineering Co ltd
Current assignee: Wuhan Mingzheng Power Engineering Co ltd
Priority date: 2023-03-30
Filing date: 2023-03-30
Publication date: 2023-07-04

Abstract

The application discloses a four-in-one low-nitrogen burner, which comprises a primary gas pipe, a central air cylinder, an outer cylinder and a secondary gas pipe, wherein the central air cylinder is sleeved on the primary gas pipe to form a primary air channel; the outer cylinder is sleeved outside the central air cylinder to form a secondary air channel; the secondary gas pipe comprises a plurality of secondary gas spray heads which are circumferentially and uniformly distributed outside the outer cylinder; the outer cylinder is provided with a combustion-supporting air inlet at one side far away from the nozzle end, a baffle is arranged in the combustion-supporting air inlet, combustion-supporting air is divided into primary air and secondary air in proportion through the baffle, the primary air enters the primary air channel, and the secondary air enters the secondary air channel; the method integrates four low-nitrogen combustion methods of air classification, gas classification, low-oxygen combustion and internal circulation of flue gas into one combustion device, so that comprehensive and integrated low-nitrogen combustion is realized.

Description

Four-in-one low-nitrogen combustor

Technical Field

The application relates to the technical field of combustors, in particular to a four-in-one low-nitrogen combustor.

Background

Along with the increasing requirements of NOx emission standards of gas boilers, stable combustion, complete combustion and non-standard CO content are required, great challenges are presented to the structures and the systems of the burners, the traditional low-nitrogen combustion equipment can only realize single-nitrogen reduction combustion measures or two-in-one nitrogen reduction combustion measures, the nitrogen reduction effect can only reach 70% at most, and for example, the nitrogen reduction effect of single-air staged combustion measures or single-fuel staged combustion measures is 50% at most. The two-in-one nitrogen reduction combustion measure generally combines air classification with flue gas recirculation or combines air classification with fuel classification, and the two modes have certain effects, but have certain limitations, namely the nitrogen reduction effect has a peak value or a balance point, the NOx emission is increased instead after passing the peak value, other problems can be caused after passing the balance point, for example, the excessive air coefficient of low-oxygen combustion is generally 0.8, and the combustion stability is influenced by flameout easily when the excessive air coefficient is smaller than 0.8; and if the flue gas recirculation rate exceeds 30%, the furnace temperature is reduced too much, combustion is unstable, and the heat loss is increased due to incomplete combustion of chemistry and machinery. It is almost impossible to achieve the goal of lower NOx emissions with a single and two-in-one nitrogen-reduction combustion.

Accordingly, in view of the deficiencies of existing burners, there is a need for a low nitrogen burner that reduces NOx emissions.

Disclosure of Invention

The embodiment of the application provides a four unification low nitrogen combustor, through concentrating on a combustion apparatus with air classification, gas classification, low oxygen combustion and four kinds of low nitrogen combustion methods of flue gas inner loop, realize synthesizing integrated, centralized low nitrogen combustion, technical scheme is as follows:

the application provides a four-in-one low-nitrogen burner which comprises a primary gas pipe, a central air cylinder, an outer cylinder and a secondary gas pipe, wherein the central air cylinder is sleeved on the primary gas pipe to form a primary air channel; the outer cylinder is sleeved outside the central air cylinder to form a secondary air channel; the secondary gas pipe comprises a plurality of secondary gas spray heads which are circumferentially and uniformly distributed outside the outer cylinder; the outer cylinder is provided with a combustion-supporting air inlet at one side far away from the nozzle end, a baffle is arranged in the combustion-supporting air inlet, combustion-supporting air is divided into primary air and secondary air in proportion through the baffle, the primary air enters the primary air channel, and the secondary air enters the secondary air channel.

For example, in a four-in-one low nitrogen burner provided in one embodiment, the inner diameter of the outer barrel decreases in a direction from the joint end toward the nozzle end so that secondary air is directed through the outer barrel to the nozzle end to create low pressure and entrain flue gas.

For example, in the four-in-one low-nitrogen burner provided in one embodiment, a flare is provided at the end of the outer cylinder facing the nozzle, and the secondary air is blown out through the flare after sucking the smoke.

For example, in the four-in-one low-nitrogen combustor provided in one embodiment, the secondary gas nozzle is a necking nozzle, the secondary gas nozzle is connected to the fire-resistant gun head towards the nozzle end, and the secondary gas is sprayed from the secondary gas nozzle to generate negative pressure and entrain smoke into the fire-resistant gun head.

For example, in the four-in-one low nitrogen combustor provided in one embodiment, a conical nozzle is provided at the refractory tip toward the nozzle end, and the conical opening of the conical nozzle is directed toward the center line of the primary gas pipe.

For example, in the four-in-one low nitrogen combustor provided in one embodiment, the excess air ratio of the combustion air is 0.85 to 0.95.

For example, in the four-in-one low-nitrogen combustor provided in one embodiment, an annular gas collection chamber is sleeved at the end, close to the joint, of the central air duct, a plurality of perforations corresponding to the secondary gas spray heads one by one are uniformly distributed in the circumferential direction of the annular gas collection chamber, one end of each secondary gas spray head penetrates through each perforation to be communicated with the annular gas collection chamber, and the other end of each secondary gas spray head penetrates out of the outer barrel.

For example, in the four-in-one low-nitrogen combustor provided in one embodiment, a secondary gas interface is provided at one side of the annular gas collection chamber, and secondary gas is injected into the annular gas collection chamber and then is distributed into a plurality of secondary gas spray heads.

For example, in the four-in-one low-nitrogen combustor provided in one embodiment, a central air gun head is provided at the end of the primary gas pipe near the nozzle, through which the primary gas is ejected at high speed.

For example, in the four-in-one low-nitrogen combustor provided in one embodiment, a swirler is arranged on the periphery of the gun head of the central air gun, and primary air in the central air barrel is sprayed out through the rotation of the swirler and is mixed with primary fuel gas sprayed out by the gun head of the central air gun for diffusion and combustion.

The beneficial effect that this application provided a trinity low nitrogen combustor brings is: the four low-nitrogen combustion methods including air classification, gas classification, low-oxygen combustion and flue gas internal circulation are concentrated on one combustion device, comprehensive integrated and centralized low-nitrogen combustion is realized, two stages of air and two stages of gas can be respectively regulated, the two stages of gas are interlocked with tail emission through a logic program, the proportions of each stage are regulated according to the content of discharged CO and NOx, oxygen-deficient combustion can be realized, oxygen-enriched combustion can be realized, and the control is flexible. The optimal excess air coefficient can be determined through the optimal operation effect, the optimal data is obtained by analyzing the four low-nitrogen combustion measures, and clean combustion is realized through precise and reasonable structural design, so that a practical basis is provided for the aim of lower emission.

Drawings

In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a left side view of a four-in-one low nitrogen combustor of the present application;

FIG. 2 is a cross-sectional view of a four-in-one low nitrogen combustor of the present application;

FIG. 3 is a schematic view of the baffle structure of the present application;

FIG. 4 is a schematic view of the annular plenum structure of the present application.

Detailed Description

The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

Unless defined otherwise, technical or scientific terms used in this disclosure should be given the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The terms "first," "second," and the like, as used in this disclosure, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.

The application provides a four-in-one low-nitrogen burner, which is shown in fig. 1-2, and is provided with a nozzle end 510 and a joint end 520, and comprises a primary gas pipe 100, a central air cylinder 200, an outer cylinder 300 and a secondary gas pipe 400, wherein the central air cylinder 200 is sleeved on the primary gas pipe 100 to form a primary air channel; the outer cylinder 300 is sleeved on the central air cylinder 200 to form a secondary air channel; the secondary gas pipe 400 comprises a plurality of secondary gas nozzles 410 which are circumferentially and uniformly distributed outside the outer cylinder 300; wherein, a combustion-supporting air inlet 310 is arranged on one side of the outer cylinder 300 far away from the nozzle end 510, a baffle 320 is arranged in the combustion-supporting air inlet 310, combustion-supporting air is divided into primary air and secondary air in proportion by the baffle 320, the primary air enters the primary air channel, and the secondary air enters the secondary air channel.

As shown in fig. 3, the baffle 320 is provided with a hole 321, the hole 321 corresponds to the end of the central air duct 200 facing the joint end 520, and the diameter of the hole 321 is the same as the diameter of the central air duct 200, so that the combustion air is split into two streams. The ratio of the primary air to the secondary air can be adjusted according to the requirements, and the specific ratio of the primary air to the secondary air is not limited, for example, the primary air accounts for 20%, the secondary air accounts for 80% and the like.

For example, in the four-in-one low nitrogen combustor provided in one embodiment, the excess air ratio of the combustion air is 0.85 to 0.95. According to the above embodiment, the low oxygen/low oxygen combustion is realized by controlling the excess air ratio α < 1 of the combustion air, avoiding the excess air ratio in the higher region of the NOx generation region, the present application sets a combustion air inlet 310 on one side of the outer cylinder 300, and the primary air and the secondary air enter through a unified combustion air inlet 310, so that the excess air ratio of the primary air and the secondary air can be kept consistent, and the excess air ratio is less than 1.

For example, in the four-in-one low nitrogen burner provided in one embodiment, as shown in fig. 2, the inner diameter of the outer barrel 300 decreases in a direction from the joint end 520 toward the nozzle end 510, so that the secondary air is guided to the nozzle end 510 through the outer barrel 300 to generate low pressure and entrain the smoke.

For example, in the four-in-one low nitrogen burner provided in one embodiment, as shown in fig. 2, a flare 330 is provided at the outer cylinder 300 toward the nozzle end 510, and the secondary air is blown out through the flare 330 after sucking the smoke.

According to the above embodiment, the secondary air is mixed with the flue gas before the nozzle end 510, and the mixed air is directly injected into the furnace through the bell mouth 330, and the unburned CO generated at the central air duct 200 is continuously burnt in an oxygen-enriched manner, so that a large amount of mixed air ensures that the combustion temperature in the area is not too high, which is beneficial to reducing NOx.

For example, in the four-in-one low nitrogen burner provided in one embodiment, as shown in fig. 2, the secondary gas nozzle 410 is a necking nozzle, the secondary gas nozzle 410 is connected to the fire-resistant gun head 420 toward the nozzle end 510, and after the secondary gas is ejected from the secondary gas nozzle 410, negative pressure is generated and the flue gas is sucked into the fire-resistant gun head 420.

For example, in the four-in-one low nitrogen burner provided in one embodiment, as shown in fig. 2, a conical nozzle 421 is provided at the refractory lance tip 420 toward the nozzle end 510, and the conical mouth of the conical nozzle 421 faces the center line of the primary gas pipe 100.

For example, in the four-in-one low-nitrogen burner provided in one embodiment, as shown in fig. 2, an annular gas collection chamber 600 is sleeved on the central air duct 200 near the joint end 520, a plurality of perforations 610 corresponding to the plurality of secondary gas nozzles 410 one by one are uniformly distributed in the circumferential direction of the annular gas collection chamber 600, one end of the secondary gas nozzle 410 is communicated with the annular gas collection chamber 600 through the perforations 610, and the other end of the secondary gas nozzle passes through the outer barrel 300.

The structure of the annular gas collecting chamber 600 is shown in fig. 4, according to the above embodiment, the annular gas collecting chamber 600 is disposed near the joint end 520 of the central air duct 200, so that the secondary fuel gas is uniformly distributed into each secondary fuel gas nozzle 410, wherein 8 to 12 secondary fuel gas nozzles 410 are uniformly disposed around the outer cylinder 300, and the secondary fuel gas nozzle 410 is configured as a necking nozzle, so that the secondary fuel gas is ejected at a high speed through the necked nozzle, and negative pressure is generated.

For example, in the four-in-one low-nitrogen burner provided in one embodiment, as shown in fig. 2, a secondary gas port 430 is provided at one side of the annular gas collection chamber 600, and secondary gas is injected into the annular gas collection chamber 600 and then is further distributed into a plurality of secondary gas nozzles 410.

For example, in the four-in-one low nitrogen burner provided in one embodiment, as shown in fig. 2, a central air gun head 110 is provided near the nozzle end 510 of the primary gas pipe 100, and primary gas is ejected at a high speed through the central air gun head 110.

According to the above embodiment, by classifying the gas, the primary gas is introduced from the center of the burner through the primary gas pipe 100, and the secondary gas is introduced through the secondary gas port 430 at the top of the burner, wherein the ratio of the primary gas to the secondary gas can be adjusted according to the requirement, the specific ratio of the primary gas to the secondary gas is not limited, for example, the primary gas ratio is 20%, the secondary gas ratio is 80%, etc.

The primary fuel gas is sprayed out through the high-speed spray nozzle of the central air gun head 110 and is mixed with primary air in a diffusing way, and as the primary air alpha is smaller than 1, a small amount of CO on the outer edge and the front edge of flame is mixed with secondary air for continuous combustion, namely the primary fuel gas can be burned out quickly without generating higher combustion temperature; the secondary gas is sprayed out at a high speed through the secondary gas spray nozzle 410 after necking, the local generated negative pressure is used for sucking surrounding high-temperature flue gas into the fire-resistant gun head 420, the concentration of combustible matters of the secondary gas is reduced due to the mixing of the flue gas, so that the low heat value of fuel is reduced, the conical mouth of the conical nozzle 421 at the front end of the fire-resistant gun head 420 faces the central line of the primary gas pipe 100, the mixed gas of the secondary gas sprayed out of the fire-resistant gun head 420 and the flue gas is diffused towards the central line, the mixed gas of the secondary gas sprayed out of the fire-resistant gun head 420 and the mixed gas of the secondary air sprayed out of the horn mouth 330 and the flue gas is diffused and mixed, and a uniform mixed field of fuel, secondary air and flue gas is formed.

For example, in the four-in-one low nitrogen burner provided in one embodiment, as shown in fig. 2, a swirler 120 is disposed on the outer periphery of the central air gun head 110, and primary air in the central air duct 200 is rotated and ejected by the swirler 120 and is mixed with primary gas ejected from the central air gun head 110 for diffusion and combustion. According to the above embodiment, by providing the swirler 120 on the outer periphery of the central air gun head 110, the primary air is rotated into the furnace through the swirler 120, and is mixed with the primary fuel gas sprayed out of the central air gun head 110 for diffusion and combustion, and the excessive air coefficient alpha of the primary air is controlled to be less than 1, so that the combustion speed and temperature are reduced due to the lack of oxygen, and the CO and N produced by combustion are mutually decomposed and compounded to form a reducing environment, thereby inhibiting the generation of fuel NOx.

As shown in fig. 1, two fire observation holes 521, a fire detector 522 for detecting whether the nozzle has a fire, and an ignition air gun assembly 523 are further provided at the joint end.

The four-in-one low-nitrogen burner can also realize internal circulation of smoke, and double internal circulation of secondary air, smoke, secondary fuel gas and smoke (two layers) is realized according to a burner nozzle structure designed by Venturi effect. The secondary air and the flue gas are recorded as a first layer of flue gas internal circulation, the secondary fuel gas and the flue gas are recorded as a second layer of flue gas internal circulation, the first layer of flue gas internal circulation is that the secondary air enters the burner and then is guided into the nozzle end 510 by the conical outer cylinder 300, the flow velocity is increased because the section is reduced, the circumferential flue gas is sucked into a secondary air channel due to the partial low pressure, the mixed gas of the secondary air and the flue gas is formed, and the combustion speed and the temperature in the furnace are reduced because the flue gas absorbs heat and dilutes the oxygen concentration, so that the thermal NOx is reduced, and the circulation amount of the flue gas in the first layer of flue gas is about 15%; the second layer of internal circulation of the flue gas is the mixing of the secondary fuel gas and the flue gas, the secondary fuel gas is arranged on the outer side of the secondary air channel, the secondary fuel gas is sprayed out through the necking secondary fuel gas spray nozzle 410 and is sucked in the flue gas, the entrainment quantity of the flue gas is about 5%, the flue gas is mixed with the secondary fuel gas to reduce the low heat value of the fuel, and the mixed gas of the flue gas and the secondary fuel gas is sprayed through the fire-resistant gun head 420 and is mixed with the mixed gas of the secondary air and the flue gas in a diffusion manner, so that the generation of rapid NOx can be inhibited. Because of the staged combustion, the combustion speeds of the flames at all stages are different, the high-speed flames drive the low-speed flames to form internal entrainment of smoke, internal smoke circulation is formed, entrainment backflow of high-temperature smoke is beneficial to stable combustion of combustible mixed gas, and meanwhile, the smoke absorbs heat to inhibit generation of thermal NOx.

According to the method, through reasonable proportion of air classification, fuel classification, flow speed and internal circulation rate of flue gas and reasonable design of the structure, the integral excess air coefficient alpha in the furnace can be stabilized to run under a lower working condition, for diffusion combustion flame, the maximum value of NOx is in an area with alpha being more than 1, the combustion efficiency can be controlled by monitoring the CO content of tail flue gas while controlling the alpha range, so that a balance point is found, the concentration of CO can be guaranteed not to be too high, and the emission concentration of NOx is also lower.

The four-in-one low-nitrogen burner concentrates the four low-nitrogen combustion methods of air classification, gas classification, low-oxygen combustion and flue gas internal circulation on one combustion device, realizes comprehensive integrated and centralized low-nitrogen combustion, can respectively regulate two-stage air and two-stage gas, has a wide regulation ratio, is interlocked with tail emission through a logic program, regulates each stage of proportion according to the content of discharged CO and NOx, can perform oxygen-deficient combustion and also perform oxygen-enriched combustion, and is flexible to control. The optimal excess air coefficient can be determined through the optimal operation effect, the optimal data is obtained by analyzing the four low-nitrogen combustion measures, and clean combustion is realized through precise and reasonable structural design, so that a practical basis is provided for the aim of lower emission.

Although embodiments of the present application have been disclosed above, it is not limited to the details and embodiments shown, it is well suited to various fields of use for the application, and further modifications may be readily made by those skilled in the art without departing from the general concepts defined by the claims and the equivalents thereof, and the application is therefore not limited to the specific details and illustrations shown and described herein.

Claims

1. A four-in-one low nitrogen burner having a nozzle end and a joint end, comprising:

a primary gas pipe;

the central air duct is sleeved on the primary gas pipe to form a primary air channel;

the outer cylinder is sleeved outside the central air cylinder to form a secondary air channel;

the secondary gas pipe comprises a plurality of secondary gas spray heads which are circumferentially and uniformly distributed outside the outer cylinder;

the outer cylinder is provided with a combustion-supporting air inlet at one side far away from the nozzle end, a baffle is arranged in the combustion-supporting air inlet, combustion-supporting air is divided into primary air and secondary air in proportion through the baffle, the primary air enters the primary air channel, and the secondary air enters the secondary air channel.

2. The four-in-one low nitrogen burner of claim 1, wherein the inner diameter of the outer barrel decreases in a direction from the joint end toward the nozzle end to cause secondary air to flow through the outer barrel to the nozzle end creating low pressure and entraining flue gas.

3. The four-in-one low nitrogen burner according to claim 2, wherein a horn mouth is arranged at the end of the outer cylinder facing the nozzle, and the secondary air is blown out through the horn mouth after sucking the smoke.

4. The four-in-one low-nitrogen burner of claim 1, wherein the secondary gas nozzle is a necking nozzle, the secondary gas nozzle is connected with a fire-resistant gun head towards the nozzle end, and the secondary gas is sprayed out of the secondary gas nozzle to generate negative pressure and entrain smoke into the fire-resistant gun head.

5. The four-in-one low nitrogen burner of claim 4, wherein a conical nozzle is provided at the refractory gun head toward the spout end, and a cone opening of the conical nozzle is directed toward a center line of the primary gas pipe.

6. The four-in-one low nitrogen burner according to claim 1, wherein the excess air ratio of the combustion air is 0.85 to 0.95.

7. The four-in-one low-nitrogen burner of claim 1, wherein an annular gas collection chamber is sleeved at the end, close to the joint, of the central air cylinder, a plurality of perforations corresponding to the secondary gas spray heads one by one are uniformly distributed in the circumferential direction of the annular gas collection chamber, one end of each secondary gas spray head penetrates through each perforation to be communicated with the annular gas collection chamber, and the other end of each secondary gas spray head penetrates out of the outer cylinder.

8. The four-in-one low nitrogen burner of claim 7, wherein a secondary gas port is provided on one side of the annular plenum, and secondary gas is injected into the annular plenum and then is split into a plurality of secondary gas nozzles.

9. The four-in-one low nitrogen burner of claim 1, wherein a central air gun tip is provided at the end of the primary gas pipe adjacent to the nozzle through which primary gas is ejected at high velocity.

10. The four-in-one low-nitrogen burner according to claim 9, wherein a swirler is arranged on the periphery of the gun head of the central air gun, and primary air in the central air barrel is sprayed out through the swirler in a rotating way and is mixed with primary fuel gas sprayed out by the gun head of the central air gun in a diffusion way.