CN115704609A

CN115704609A - Air heating furnace and air heating method

Info

Publication number: CN115704609A
Application number: CN202110883884.XA
Authority: CN
Inventors: 王伟; 程高锋; 王瑞星
Original assignee: Luoyang Mingyuan Petrochemical Industry Technology Co ltd
Current assignee: Luoyang Mingyuan Petrochemical Industry Technology Co ltd
Priority date: 2021-08-03
Filing date: 2021-08-03
Publication date: 2023-02-17

Abstract

The invention discloses an air heating furnace, comprising: the vertical furnace body limits a hearth, and a primary air inlet and a heating air outlet which are positioned at two ends; and the burner is arranged in the hearth close to the primary air inlet, wherein the air heating furnace further comprises a secondary air inlet and a secondary air distributor communicated with the secondary air inlet, the secondary air inlet is arranged between the burner and the hot air outlet, and the secondary air distributor introduces secondary air into the position outside a combustion area of the burner in the hearth through the secondary air inlet and is used for mixing with flue gas combusted by the burner. The invention also discloses an air heating method. According to the air heating furnace and the air heating method, the fuel can be completely combusted by introducing primary air, and the air temperature can be ensured to reach the required temperature by introducing secondary air, so that the novel air heating furnace and the novel air heating method which have good combustion effect, clean combustion products and uniform temperature can be provided.

Description

Air heating furnace and air heating method

Technical Field

The present invention relates to the fields of oil refining, chemical engineering, and the like, and more particularly, to an air heating furnace for providing a process system with a temperature suitable for use. The invention also relates to an air heating method.

Background

The air heating furnace is an important facility in the starting and running processes of devices in the petrochemical industry, and is mainly used for providing heat for a process system so as to be used for device material reaction or catalyst regeneration, such as a propane dehydrogenation device, an MTO reactor hot blast stove, an activated carbon desulfurization device and an activated carbon regeneration unit hot blast stove. The air heating furnace can also be used for providing energy for starting up a process system or providing a heat source for drying refractory materials in the lining of equipment, such as an auxiliary combustion chamber of a catalytic cracking unit, an auxiliary combustion chamber of an MTO (methanol to olefins) unit regenerator and the like.

The existing air heating furnace and air heating method have the problems of low combustion efficiency, easy flameout, poor flame temperature uniformity of a hearth, overproof nitrogen oxide content in outlet flue gas, substandard environmental protection, poor flue gas outlet temperature uniformity and the like in the operation process, are difficult to meet the process requirements, and seriously affect the stable operation of the device.

In order to solve the above problems, a novel air heating furnace and an air heating method which have good combustion effect, clean combustion products and uniform temperature are required.

Disclosure of Invention

It is an object of the present invention to provide an air heating furnace and an air heating method which at least improve the above-mentioned problems.

According to an aspect of the present invention, there is provided an air heating furnace comprising:

the vertical furnace body limits a hearth, and a primary air inlet and a heating air outlet which are positioned at two ends; and

a burner which is arranged in the hearth near the primary air inlet,

the air heating furnace also comprises a secondary air inlet and a secondary air distributor communicated with the secondary air inlet, the secondary air inlet is arranged between the combustor and the hot air outlet, and the secondary air distributor introduces secondary air into the hearth through the secondary air inlet at a position outside a combustion area of the combustor and is used for uniformly distributing the secondary air and mixing the secondary air with flue gas combusted by the combustor.

The invention introduces primary air through the primary air inlet to fully combust the fuel, and introduces uniformly distributed secondary air through the secondary air inlet and the secondary air distributor to uniformly mix with flue gas generated after the fuel is combusted, thereby providing clean, stable and uniform heated air for use.

Preferably, the secondary air distributor is arranged in the hearth between the burner and the heating air outlet, the secondary air distributor comprises a main pipe and branch pipes, one end of the main pipe is communicated with the secondary air inlet, the other end of the main pipe is communicated with the branch pipes, the branch pipes are provided with uniformly distributed discrete air nozzles, and the discrete air nozzles are used for uniformly distributing secondary air in the hearth.

Preferably, the discrete nozzle opening direction is at an angle of 0 to 90 degrees to the vertically downward direction.

Preferably, the branch pipe of the secondary air distributor further comprises a part of downstream discrete air nozzles, the opening direction of the downstream discrete air nozzles is at an angle of more than 90 degrees and less than or equal to 180 degrees with the vertical downward direction, and the number of the downstream discrete air nozzles is less than that of the discrete air nozzles.

Preferably, the branch pipes of the secondary distributor are at least one circle of annular pipes which are arranged in the horizontal direction and communicated with the cross section of the furnace body in a concentric manner, a plurality of parallel straight pipes which are arranged in the horizontal direction and communicated with a transverse pipe and are vertical to the transverse pipe, a plurality of parallel straight pipes which are arranged in the horizontal direction and communicated with a plurality of parallel transverse pipes and are vertical to the transverse pipe, and a plurality of straight pipes which are arranged in the horizontal direction and communicated with each other and are radial from the center.

Preferably, the burner is a cyclone burner, and comprises at least one air cyclone sheet arranged along at least one circular ring in the horizontal direction, wherein the air cyclone sheets in each circular ring are arranged at equal intervals and are arranged at an angle with the horizontal plane, so that the introduced primary air forms a rotating and ascending air flow.

Preferably, said at least one ring is arranged concentrically; the at least one circular ring comprises at least one large circular ring and a plurality of small circular rings which are arranged in the large circular ring and are uniformly distributed around the large circular ring in a circular manner; or the plurality of circular rings comprise a plurality of small circular rings which are uniformly distributed on one or more large circular rings which are concentrically arranged with the cross section of the furnace body.

Preferably, the fuel of the burner is injected parallel to the air swirl plates and towards the axis of the vertical furnace.

Preferably, the nozzle opening for the fuel is provided in the middle of the air swirler plate, and the nozzle opening for the fuel is provided on each air swirler plate or every other air swirler plate of the same number.

Preferably, the fuel comprises gas and oil.

Preferably, the air heating furnace further comprises a static mixer disposed at the heated air outlet for further mixing the heated air uniformly.

Preferably, the static mixer is in the form of an annular swirl plate structure, a plurality of juxtaposed laval tubes or a grid.

According to another aspect of the present invention, there is provided an air heating method including:

introducing primary air and fuel into a burner of the air heating furnace to fully combust the fuel;

introducing secondary air outside a combustion area of a combustor in a hearth of the air heating furnace, and mixing the secondary air with flue gas generated after fuel combustion; and

and outputting the mixed heated air from an outlet of the air heating furnace for use.

Preferably, the method further comprises:

measuring the temperature of the flue gas after the fuel is combusted, and adjusting the amount of primary air according to the temperature of the flue gas.

Preferably, the method further comprises:

measuring the heated air temperature at the outlet of the air heating furnace, and adjusting the amount of secondary air and/or fuel according to the heated air temperature at the outlet.

Preferably, the sequence of the introduction of the primary air and the secondary air can be adjusted according to the temperature of the air heated at the outlet.

Preferably, the primary air is introduced in a swirling manner, and the secondary air is introduced in a manner of being uniformly distributed along the cross section of the air heating furnace.

According to the air heating furnace and the air heating method, the fuel can be completely combusted by introducing primary air, and the air temperature can be ensured to reach the required temperature by introducing secondary air, so that the novel air heating furnace and the novel air heating method which have good combustion effect, clean combustion products and uniform temperature can be provided.

Drawings

FIG. 1 is a front view of an air heating furnace according to a first embodiment of the present invention;

FIG. 2 is a top cross-sectional view of the air heating furnace shown in FIG. 1, taken in horizontal cross-section between the branch ducts and the heated air outlets of the secondary air distributor, showing the construction of the secondary air distributor;

FIG. 3 is a top cross-sectional view of the air furnace shown in FIG. 1, taken in horizontal cross-section between the burner and the secondary air distributor, showing the burner configuration;

FIG. 4 is a front view of an air heating furnace according to a second embodiment of the present invention;

FIG. 5 is a top plan view of the static mixer of the air heating furnace shown in FIG. 4;

FIG. 6 is a front view of an air heating furnace according to a third embodiment of the present invention;

FIG. 7 is a front view of an air heating furnace according to a fourth embodiment of the present invention;

FIG. 8 is a top cross-sectional view of the air heating furnace shown in FIG. 7, taken in horizontal cross-section between the secondary air distributor manifold and the heating air ports, showing the configuration of the secondary air distributor;

FIG. 9 is a top cross-sectional view of the air furnace shown in FIG. 7, taken in horizontal cross-section between the burner and the secondary air distributor, showing the burner configuration;

FIG. 10 is a front view of an air heating furnace according to a fifth embodiment of the present invention;

FIG. 11 is a top cross-sectional view of the air heating furnace shown in FIG. 10, taken in horizontal cross-section between the secondary air distributor manifold and the air addition outlets, showing the air distributor configuration;

FIG. 12 is a top cross-sectional view of the air furnace shown in FIG. 10, taken in horizontal cross-section between the burner and the secondary air distributor, showing the burner configuration;

FIG. 13 is a schematic illustration of an air heating method according to a first embodiment of the present invention;

fig. 14 is a schematic view of an air heating method according to a second embodiment of the present invention.

Detailed Description

The present application is described in further detail below. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict.

For clarity of description, in the present description and in the drawings, the terms "vertical direction" and "horizontal direction" are used in a directional description with respect to the vertical direction of use of the air heating furnace and the direction shown in the drawings, and the terms are used for illustration and not limitation of the structure, which is not limited to use in other directions.

Fig. 1 is a front view of an air heating furnace according to a first embodiment of the present invention. The air heating furnace is generally designated by the reference numeral 10 and comprises an upright body 11 defining a hearth and primary air inlets 111 and heated air outlets 112 at either end. The burner 12 is disposed in the furnace near the primary air inlet 111. The air heating furnace 10 further includes a secondary air inlet 14 and a secondary air distributor 13 communicating with the secondary air inlet 14, the secondary air inlet 14 being disposed between the burner 12 and the hot air outlet 112. The secondary air distributor 13 introduces secondary air into the furnace body through the secondary air inlet 14 to a position outside the combustion zone of the burner 12 for mixing with the flue gas combusted by the burner 12.

The combustion area of the burner 12 refers to an area where combustion air can participate in combustion together with fuel, and in the present invention, the combustion air includes only primary air, and secondary air does not participate in combustion together with fuel, i.e., the secondary air is introduced into a position outside the combustion area of the burner 12 in the furnace for mixing with flue gas after combustion by the burner 12.

FIG. 2 is a top cross-sectional view of the air heating furnace shown in FIG. 1, taken in horizontal cross-section between the secondary air distributor manifold and the heated air outlet, showing the configuration of the secondary air distributor. In fig. 2, the secondary air distributor, generally designated by reference numeral 13, includes a main pipe 131 and a branch pipe 132, the main pipe 131 having one end communicating with the secondary air inlet 14 and the other end communicating with the branch pipe 132. The branch pipes 132 are a plurality of parallel straight pipes arranged in the horizontal direction and connected by a horizontal pipe, and are perpendicular to the horizontal pipe. The branch pipe 132 is provided with uniformly distributed discrete air nozzles 1321, and the discrete air nozzles 1321 are used for uniformly distributing secondary air in the furnace.

The direction of the opening of the discrete air nozzles 1321 may preferably be at an angle of 0 to 90 degrees to the vertically downward direction, so that the distance from the mixing zone to the heating air outlet 112 is longer and the mixing time is longer, which is more advantageous for the secondary air to be uniformly mixed with the flue gas after combustion by the burner 12. In theory, however, the discrete air nozzles 1321 may also include a portion of downstream discrete air nozzles having openings oriented at an angle of 0 to 90 degrees from the vertically upward direction and at an angle of greater than 90 degrees and less than or equal to 180 degrees from the vertically downward direction, and the number of downstream discrete air nozzles is less than the number of discrete air nozzles, so that the secondary air is uniformly mixed with the heated flue gas after combustion by the burner 12.

The lower end of the main tube 131 of the secondary air distributor 13 may also include discrete air nozzles, as shown in FIG. 1.

The secondary air distributor 13 in this embodiment may also be replaced by a plurality of parallel straight tubes arranged in the horizontal direction and connected by a plurality of parallel horizontal tubes perpendicular to the horizontal tubes.

FIG. 3 is a top sectional view of the air heating furnace shown in FIG. 1, taken in horizontal cross section between the burners and the secondary air distributor manifold, showing the burner configuration. In the figure, the burners are generally indicated by reference numeral 12, and the burners 12 are cyclone burners, which are disposed in the hearth of the furnace body 11, and include primary burners 121 disposed in a circular ring shape in the horizontal direction at the inner circumference and secondary burners 122 disposed in a circular ring shape at the outer circumference. The primary burner 121 comprises a circle of uniformly arranged primary vortex sheets 1211 arranged at equal intervals, the secondary burner 122 comprises a circle of uniformly arranged secondary vortex sheets 1221 arranged at equal intervals, the primary burner 121 and the secondary burner 122 are arranged concentrically, each primary vortex sheet 1211 or each secondary vortex sheet 1221 is inclined and angled to the horizontal plane, a gap angled to the horizontal plane is formed between every two adjacent primary vortex sheets 1211 or between every two adjacent secondary vortex sheets 1221, the lower end of the gap is communicated with primary air entering from the air inlet 111, the upper end of the gap is communicated with the hearth, so that the primary air passing through the gap forms rotating and rising air flow, and uniform distribution of the primary air or uniform mixing of flue gas and secondary air after combustion of the burner 12 is promoted.

In this embodiment, each of the primary and

secondary vanes

1211 and 1221 of the burner 12 is provided with a primary or secondary fuel lance nozzle 1212 and 1222, preferably through each of the primary or

secondary vanes

1211 and 1221, disposed in the middle thereof, the primary or secondary fuel lance nozzle 1212 or 1222 being flat, the fuel sprayed from the primary or secondary fuel lance nozzle 1212 or 1222 is directed parallel to the corresponding primary or

secondary vane

1211 or 1221 and toward the axis of the vertical furnace body 11 and mixes with the air flowing from the gap between the primary or

secondary vane

1211 or 1221 and its adjacent vanes, and the primary or

secondary vanes

1211 and 1221 and the primary or secondary fuel lance nozzle 1222 of the burner 12 facilitate the flow of the primary air and fuel while increasing the mixing intensity of the primary air and the fuel.

In this embodiment, the burner 12 is not limited to the first and

second swirl disks

1211 and 1221 shown in the drawings, and may include a plurality of stages, such as three stages or four stages, as desired. The number of primary or secondary fuel lance ports 1212 or 1222 need not correspond one-to-one to the number of primary or

secondary swirler vanes

1211 or 1221, and one primary or secondary burner lance port 1212 or 1222 may be provided for every other one or more primary or

secondary swirler vanes

1211 or 1221.

Fig. 4 is a front view of an air heating furnace according to a second embodiment of the present invention. The same components in the air heating furnace of the second embodiment of the present invention are given the same reference numerals as in the first embodiment, and only the second digit is increased by 1 for the sake of distinction.

The air heating furnace 20 of the second embodiment shown in fig. 4 differs from the air heating furnace 10 of the first embodiment only in that the air heating furnace 20 of the second embodiment further includes a static mixer 25. The static mixer 25 is provided at the heated air outlet 212 of the air heating furnace 20.

FIG. 5 is a top view of the static air mixer of the air furnace shown in FIG. 4. FIG. 5 shows that the static mixer 25 is also a swirler structure, including the static mixer swirler 251. When the air flows through the swirl plate 251 of the static mixer, the air is pressed by the swirl plate to rotate, and the flue gas combusted by the combustor 12 is further uniformly mixed with the secondary air introduced by the secondary air distributor 13.

Fig. 6 is a front view of an air heating furnace according to a third embodiment of the present invention. The same components in the air heating furnace of the third embodiment of the present invention are given the same reference numerals as in the second embodiment, and only the second digit is increased by 1 for the sake of distinction.

The air heating furnace 30 of the third embodiment shown in fig. 6 is different from the air heating furnace 20 of the second embodiment only in that the static mixer 35 of the air heating furnace 30 of the third embodiment is composed of a plurality of laval tubes (not shown) arranged in parallel in a tapered shape, instead of the static mixer 25 composed of the swirling plates 251 in the air heating furnace 20 of the second embodiment. When the flue gas passes through the converging-diverging laval tube of the static mixer 35, the high-temperature flue gas after combustion of the mixed combustor 32 and the low-temperature secondary air introduced by the secondary air distributor 13 are pressed against the wall of the laval tube, and are mixed vigorously, so that the high-temperature flue gas and the low-temperature secondary air are further mixed uniformly, and the temperature of the air flowing out of the heated air outlet 312 is more uniform.

The static mixer 35 of the air heating furnace 30 according to the third embodiment of the present invention can also be replaced by a static mixer in the form of a grid, which can also achieve the rectification effect on the high-temperature flue gas and the low-temperature secondary air, so that the high-temperature flue gas and the low-temperature secondary air are further uniformly mixed, and thus the temperature of the air flowing out of the heating air outlet 312 is more uniform.

Fig. 7 is a front view of an air heating furnace according to a fourth embodiment of the present invention. The same components in the air heating furnace of the fourth embodiment of the present invention are given the same reference numerals as in the second embodiment, and only the second digit is increased by 2 for the sake of distinction.

The air heating furnace 40 of the fourth embodiment and the air heating furnace 20 of the second embodiment each include a furnace body and a burner, a secondary air distributor and a static mixer provided in a furnace, except that the burner 42 of the air heating furnace 40 and the burner 22 of the air heating furnace 20 are different, and the secondary air distributor 43 of the air heating furnace 40 and the secondary air distributor 23 of the air heating furnace 20 are different, and the specific structures of the burner 42 and the secondary air distributor 43 of the air heating furnace 40 of the fourth embodiment will be described in detail below with reference to fig. 8 and 9.

FIG. 8 is a top cross-sectional view of the air heating furnace shown in FIG. 7, taken in horizontal cross-section between the secondary air distributor manifold and the heated air outlets, showing the configuration of the secondary air distributor.

In fig. 8, the secondary air distributor, generally designated by reference numeral 43, includes a main pipe 431 and a branch pipe 432, the main pipe 431 having one end communicating with the secondary air inlet 44 and the other end communicating with the branch pipe 432. The branch pipe 432 is a ring of annular pipes which are arranged in the horizontal direction and are communicated with the furnace body concentrically with the cross section. The branch pipe 432 is provided with uniformly distributed discrete air nozzles 4321, and the discrete air nozzles 4321 are used for uniformly distributing secondary air in the furnace.

With further reference to FIG. 8, the opening direction of the discrete air nozzles 4321 may preferably be at an angle of 0 to 90 degrees from the vertically downward direction, so that the distance from the mixing zone to the heating air outlet 412 is longer, and the mixing time is also longer, which is more advantageous for the uniform mixing of the secondary air with the flue gas after combustion by the burner 42. In theory, however, the discrete air nozzles 4321 may also include a part of downstream discrete air nozzles having an opening direction forming an angle of 0 to 90 degrees with the vertical upward direction and an angle of more than 90 degrees and less than or equal to 180 degrees with the vertical downward direction, and the number of downstream discrete air nozzles is less than the number of discrete air nozzles, so that the secondary air can be uniformly mixed with the heated flue gas after combustion by the burner 42.

The underside of the main tube 431 of the secondary air distributor 43 may also include discrete air nozzles.

In this embodiment, the branch 432 is not limited to one turn as shown in the figure, and may include at least one concentric turn, or a plurality of turns in parallel.

FIG. 9 is a top cross-sectional view of the air furnace shown in FIG. 7, taken in horizontal cross-section between the burner and the secondary air distributor, showing the burner configuration. In fig. 9, the burners are generally indicated by reference numeral 42, and the burners 42 are cyclone burners, which are disposed in the hearth of the furnace body 41, and include primary burners 421 located at the inner circle and uniformly arranged at the four vertices of a square, and secondary burners 422 located at the outer circle and arranged in a circular shape. The primary burners 421 each include primary swirl plates 4211 arranged uniformly at equal angles from the center, and gaps are formed between adjacent primary swirl plates 4211. The secondary burner 422 comprises a circle of secondary vortex sheets 4221 which are arranged at equal intervals and concentric with the hearth 41, each secondary vortex sheet 4221 is inclined to form an angle with the horizontal plane, and a gap which forms an angle with the horizontal plane is formed between every two adjacent secondary vortex sheets 4221. The lower end of the gap between the first-stage cyclone sheet 4211 and the second-stage cyclone sheet 4221 is communicated with primary air entering from the air inlet 411, and the upper end of the gap is communicated with the hearth, so that the primary air passing through the gap forms rotating and rising air flow, and the uniform distribution of the primary air or the uniform mixing of flue gas and secondary air after the combustion of a combustor is promoted.

In this embodiment, each of the primary burners 421 has a fuel spray gun nozzle 4212 at the center, and every other secondary swirler 4221 has a secondary fuel spray gun nozzle 4222, the secondary fuel spray gun nozzles 4222 preferably pass through the corresponding secondary swirler 4221 and are arranged in the middle, the secondary fuel spray gun nozzles 4222 are flat, the fuel sprayed from the fuel spray gun nozzles 4222 is parallel to the corresponding secondary swirler 4221 and is sprayed toward the axis of the vertical burner 41, and is mixed with the air flowing out from the gap between the secondary swirler 4221 and its adjacent swirler and the air flowing out from the gap between the primary swirlers 4211, and the primary swirler 4211 and the primary fuel spray gun nozzle 4212 of the burner 42 or the secondary swirler 4221 and the secondary fuel spray gun 4222 are configured to facilitate the flow of the primary air and the fuel and to increase the mixing strength of the primary air and the fuel.

In this embodiment, the burner 42 is not limited to the illustrated arrangement including the first and

second stages

4211 or 4221, and may include a plurality of stages, such as three or four stages, as desired. The number of secondary fuel lance orifices 4222 need not be provided every other secondary swirler 4221, the secondary combustion lance orifices 4222 may be provided every other one or more secondary swirlers 4221, or the number of secondary swirlers 4221 may correspond one-to-one to the number of secondary fuel lance orifices 4222.

Fig. 10 is a front view of an air heating furnace according to a fifth embodiment of the present invention, and the same components in the air heating furnace of the fifth embodiment of the present invention are given the same reference numerals as in the second embodiment, and only the second digit is increased by 3 for the sake of distinction.

The air heating furnace 50 of the fifth embodiment and the air heating furnace 20 of the second embodiment each include a furnace body and a burner, a secondary air distributor and a static mixer provided in a furnace, except that the burner 52 of the air heating furnace 50 and the burner 22 of the air heating furnace 20 are different, and the secondary air distributor 53 of the air heating furnace 50 and the secondary air distributor 23 of the air heating furnace 20 are different, and the specific structures of the burner 52 and the secondary air distributor 53 of the air heating furnace 50 of the fifth embodiment will be described in detail with reference to fig. 11 and 12.

FIG. 11 is a top sectional view of the air furnace shown in FIG. 10 taken in a horizontal cross section between the secondary air distributor manifold and the furnace outlet showing the secondary air distributor configuration.

In fig. 11, the secondary air distributor, generally designated by reference numeral 53, includes a main pipe 531 and a branch pipe 532, and one end of the main pipe 531 communicates with the secondary air inlet 54 and the other end communicates with the branch pipe 532. The branch pipes 532 are a plurality of straight pipes arranged in the horizontal direction and communicated with each other and radiating from the center. The branch pipes 532 are provided with uniformly distributed discrete air nozzles 5321, and the discrete air nozzles 5321 are used for uniformly distributing secondary air in the furnace.

The opening direction of the discrete air nozzles 5321 may preferably be at an angle of 0 to 90 degrees from the vertically downward direction, so that the distance from the mixing area to the heating air outlet 512 is longer, and the mixing time is longer, which is more favorable for the uniform mixing of the secondary air and the flue gas after combustion by the burner 52. In theory, however, the discrete air nozzles 5321 may also include a portion of downstream discrete air nozzles having openings oriented at an angle of 0 to 90 degrees from the vertically upward direction and at an angle of greater than 90 degrees and less than or equal to 180 degrees from the vertically downward direction, and the number of downstream discrete air nozzles is less than the number of discrete air nozzles, so that the secondary air is uniformly mixed with the heated flue gas after combustion by the burner 52.

The underside of the main tube 431 of the secondary air distributor 53 may also include discrete air nozzles.

In this embodiment, the branch pipe 532 is not limited to one layer shown in the figure, and may include at least two layers in parallel.

FIG. 12 is a top cross-sectional view of the air furnace shown in FIG. 10, taken in horizontal cross-section between the burner and the secondary air distributor, showing the burner configuration.

In the figure, the burners are generally designated by reference numeral 52, and the burners 52 are cyclone burners disposed in the hearth of the furnace body 51, and include a primary burner 521 located at the center of the cross section of the furnace body 51, and a secondary burner 522 located at the outer periphery and arranged in a circular ring shape. The primary burner 521 and the secondary burner 522 each include a primary swirl plate 5211 and a secondary swirl plate 5221 that are equiangularly and uniformly arranged from the center, and a gap is formed between adjacent primary swirl plates 5211 or secondary swirl plates 5221. The lower end of the gap between the first-stage cyclone sheet 5211 and the second-stage cyclone sheet 5221 is communicated with the primary air entering from the air inlet 511, and the upper end of the gap is communicated with the hearth, so that the primary air passing through the gap forms a rotating and ascending air flow, and the uniform distribution of the primary air or the uniform mixing of the flue gas and the secondary air after the combustion of the combustor is promoted.

In this embodiment, the primary swirler 521 and each secondary swirler 522 of the burner 52 are centrally provided with the primary fuel spray gun nozzle 5212 or the secondary fuel spray gun nozzle 5222, and the primary swirler plate 5211 or the secondary swirler plate 5221 and the primary fuel spray gun nozzle 5221 or the secondary fuel spray gun nozzle 5222 of the burner 52 are configured to facilitate the flow of the primary air and the fuel and increase the mixing strength of the primary air and the combustion fuel.

In this embodiment, the burner 52 is not limited to the illustrated configuration including one and two stages of swirl plates, and may include multiple stages, such as three or four stages, as desired.

Fig. 13 is a schematic view of an air heating method according to a first embodiment of the present invention. The air heating furnace is generally indicated at 60. The air heating furnace 60 includes a vertical body 61, the body 61 defining a furnace chamber and primary air inlets 611 and heated air outlets 612 at opposite ends of the vertical body, and the air heating furnace 60 further includes burners 62, secondary air distributors 63 and static mixers 65 disposed within the furnace chamber.

Burners 62 are positioned adjacent primary air inlet 611 and include primary burner 621, secondary burner 622, and fuel lance 623. The secondary air distributor 63 includes a main pipe 631 and a branch pipe 632, one end of the main pipe 631 being in fluid communication with the secondary air inlet 64, and the other end of the main pipe 631 being in fluid communication with the branch pipe 632.

Outside air is supplied to the air heating furnace 60 through an air line 66 by an air blowing system 67. The air line 66 includes a primary air line 661 in fluid communication with the blower system 67, the primary air line 661 controlling the total amount of air admitted via a first valve 681 and the amount of primary air via a second valve 682 mounted on the primary air line 662, and a secondary air line 663 for branching secondary air from the primary air line 661 to the secondary air inlet 64.

The air heating method according to the first embodiment of the present invention includes supplying primary air to the burners 62 of the air heating furnace 60 via the main pipe 661 and the primary air line 662 via the blower system 67, and supplying fuel to the burners 62 via the fuel lances 623, the amounts of the primary air and the fuel being controlled so that the fuel can be sufficiently burned at a temperature of about 900 degrees celsius, thereby cleaning the combustion products.

While the burners 62 are burning, the secondary air is introduced into the furnace of the air heating furnace 60 through the main pipe 661 and the secondary air pipe 663 to the secondary air inlet 64 fluidly connected to the secondary air distributor 63 via the blower system 67, to the outside of the combustion region of the burners 62, and is mixed with the flue gas after the fuel of the burners 62 is burned.

The burner 62 is preferably arranged in a swirling manner, so that the flue gas after the fuel combustion rises spirally and is uniformly distributed and mixed with the secondary air uniformly distributed in the hearth through the secondary air distributor 63, so that the heated air which is uniformly mixed and has uniform temperature and is composed of the secondary air and the flue gas after the fuel combustion can be obtained, and the heated air after being mixed is preferably further mixed through the static mixer 65, so that the mixed heated air can be output from the outlet of the air heating furnace for use.

The air heating method according to the first embodiment of the present invention is not limited to the specific structure shown in fig. 13, and the specific structure shown in fig. 13 is for convenience of description only, and the air heating method according to the first embodiment of the present invention may include only the following steps:

Fig. 14 is a schematic view of an air heating method according to a second embodiment of the present invention. The same or similar parts in the schematic view of the air heating method of the second embodiment as in the schematic view of the heating method of the first embodiment are denoted by the same reference numerals, and only the first digit on the left is increased by 1 for the sake of distinction.

In fig. 14, an air heating furnace is generally indicated at 70. The air heating method according to the second embodiment of the present invention is different from the air heating method of the first embodiment in that, in the second embodiment, the flue gas temperature T2 after combustion of the fuel is measured, and the amounts of primary air and fuel are adjusted according to the flue gas temperature T2. Through controlling the flue gas temperature T2 after the fuel burning, the burning can be fully burnt, and the combustion products are cleaner.

Also, it is preferable to measure the heated air temperature T1 at the outlet of the air heating furnace 70, and adjust the amount of secondary air via the third valve 783 on the secondary air line 763, the amount of fuel via the fourth valve 784 on the fuel line 723, or both, according to the heated air temperature T1, so that sufficient combustion of air can be ensured, the combustion products can be cleaner, the fuel utilization efficiency can be improved, and it can be ensured that the heated air temperature T1 provided by the air heating furnace 70 can be maintained within a desired range, and the adjustment is more flexible, more convenient in operability and adjustability, and optimized in use.

Meanwhile, by optimizing the structure of the burner 72, rotational flow airflow is generated, the turbulence degree is high, the mixing effect is good, the structure of the secondary air distributor 73 is optimized, secondary air which is uniformly distributed on the cross section of the air heating furnace 70 is provided, and combustion is facilitatedThe material and the combustion-supporting air are mixed, so that the heated air output by the air heating furnace 70 is uniformly mixed, the temperature T1 of the heated air is more uniform, and the high stability and the ultralow NO of the heating furnace are ensured _x And (4) discharging and improving the performance of the air heating furnace 70.

And secondary air enters the hearth through the air distributor 73 and is mixed with high-temperature flue gas of high-strength rotational flow, so that the mixing effect is enhanced, the mixed gas is more uniform and stable, and the radial and axial temperature uniformity in the hearth can be effectively ensured. The outlet portion of the air heating furnace 70 is provided with a static mixer 75, which rotates while the fluid flows through the static mixer, constantly changing the flow direction, pushing not only the central fluid flow toward the periphery but also the peripheral fluid flow toward the center, thereby causing a good radial mixing effect. The perfect radial circulation mixing effect enables the temperature gradient, the velocity gradient and the mass gradient of the heated air on the cross section of the output pipeline to be obviously reduced.

The air heating method according to the second embodiment of the present invention is also not limited to the specific structure shown in fig. 14, the specific structure shown in fig. 14 is for convenience of explanation, and the air heating method according to the second embodiment of the present invention may include only the following steps:

outputting the mixed heated air from an outlet of the air heating furnace for use;

Preferably, the order of introduction of the primary air and of the secondary air can be adjusted according to the temperature of the air heated at the outlet and/or the primary air is introduced in a swirling manner and the secondary air is introduced in a uniformly distributed manner along the cross section of the air heating furnace.

The different burner configurations, air distributor configurations and static mixer configurations described in the air heating furnace according to various embodiments of the present invention may be combined with each other to form new embodiments that differ from the illustrated embodiments, all within the scope of the present invention.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention according to the present application is not limited to the specific combination of the above-mentioned features, but also covers other embodiments where any combination of the above-mentioned features or their equivalents is made without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. An air heating furnace comprising:

a burner which is arranged in the hearth near the primary air inlet,

2. An air heating furnace according to claim 1, wherein the secondary air distributor comprises a main pipe and a branch pipe, one end of the main pipe is communicated with the secondary air inlet, the other end is communicated with the branch pipe, and the branch pipe is provided with uniformly distributed discrete air nozzles for uniformly distributing the secondary air in the furnace.

3. An air heater according to claim 2, wherein said discrete nozzle opening direction is at an angle of 0 to 90 degrees to a vertically downward direction.

4. An air heater according to claim 3, wherein said manifold of said secondary air distributor further comprises a plurality of downstream discrete air nozzles, said downstream discrete air nozzles having an opening direction that is at an angle of greater than 90 degrees and less than or equal to 180 degrees from a vertically downward direction, and said number of downstream discrete air nozzles being less than said number of discrete air nozzles.

5. An air heating furnace according to claim 2, wherein the branch pipes of the secondary distributor are at least one ring pipe arranged in the horizontal direction and communicating with the cross section of the furnace body concentrically, a plurality of parallel straight pipes arranged in the horizontal direction and communicating with a cross pipe and perpendicular to the cross pipe, a plurality of parallel straight pipes arranged in the horizontal direction and communicating with a plurality of parallel cross pipes and perpendicular to the cross pipe, and a plurality of straight pipes arranged in the horizontal direction and communicating with each other and radiating from the center.

6. An air heater according to claim 1, wherein said burners are cyclone burners comprising air swirlers arranged in at least one horizontal ring, the air swirlers in each ring being equally spaced and angled from the horizontal to provide a swirling rising air flow of the incoming primary air.

7. An air heating furnace according to claim 6, wherein said at least one ring is concentrically arranged; the at least one circular ring comprises at least one large circular ring and a plurality of small circular rings which are arranged in the large circular ring and are circularly and uniformly distributed around the large circular ring; or the plurality of circular rings comprise a plurality of small circular rings which are uniformly distributed on one or more large circular rings which are concentrically arranged with the cross section of the furnace body.

8. An air heater according to claim 6 or 7, wherein the fuel of said burner is injected parallel to said air swirler and towards the axis of said vertical body.

9. An air heater according to claim 8, wherein fuel lance ports are provided in the middle of said air swirler, said fuel lance ports being provided on each or every other same number of air swirlers.

10. An air heating furnace according to claim 8, wherein said fuel comprises gas and oil.

11. An air heating furnace according to any one of claims 1-7, wherein said air heating furnace further comprises a static mixer disposed at the heated air outlet for further homogenizing the heated air.

12. An air heater according to claim 11, wherein said static mixer is in the form of an annular swirl plate structure, a plurality of juxtaposed laval tubes or a grid.

13. A method of heating air, comprising:

14. The air heating method according to claim 13, wherein the method further comprises:

15. The air heating method according to claim 13 or 14, wherein the method further comprises:

16. The air heating method according to claim 13 or 14, wherein the sequence of the introduction of the primary air and the secondary air is adjustable according to the temperature of the air heated at the outlet.

17. The air heating method according to claim 16, wherein the primary air is introduced in a swirling manner, and the secondary air is introduced in a uniformly distributed manner along a cross-section of the air heating furnace.