JPH05658Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a premixed low NOx gas burner, and in particular to a premixed low NOx gas burner that allows easy adjustment of both the primary air flow rate and the secondary air flow rate at the back of the burner.
Regarding NOx gas burners.

[Prior art] Conventionally, a part of combustion air (primary air) is mixed with gas fuel in advance, then combusted (primary combustion), and the remainder of the combustion air (secondary air) is added to the primary combustion gas. In a premixed low NOx gas burner that mixes and burns (secondary combustion), adjusting the flow rate of secondary air is a complicated mechanism, and when using preheated air to save energy, it is difficult to operate. Ta.

[Problem that the invention aims to solve] However, when high-temperature air that has been heat exchanged with exhaust gas, etc. is used as combustion air as an energy-saving measure, the NOx value increases, so as a measure to reduce it, only primary air is used. In addition, it is necessary to easily adjust the flow rate of secondary air. Therefore, unlike conventional premixed gas burners, it has been desired to propose a premixed low NOx gas burner that can adjust the flow rate of both primary air and secondary air at the back of the burner.

This idea was created in consideration of the above circumstances.
An object of the present invention is to provide a premixed low NOx gas burner that can easily adjust the flow rate of secondary air.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses a part of air preheated by exhaust gas, etc. as primary air, and premixes it with fuel in a cylindrical ventilate mixer. While forming a combustion vortex, the remainder of the air is guided perpendicularly to the outer periphery of the ventilary mixer as secondary air, and then passed along the outer periphery and guided to the secondary combustion zone by a swirl vane provided near the downstream end of the burner tip. In premixed low NOx gas burners,
An air duct for guiding combustion air to the inside and outer periphery of the ventilary mixer is provided around the ventilium mixer, and the air duct is arranged so that the secondary air flows from the most upstream part to the most downstream part of the outer periphery of the ventilary mixer. A flange portion and a bending portion are provided at the most upstream portion of the ventilate mixer to smoothly change the direction of the secondary air guided perpendicularly to the outer periphery of the ventilary mixer along the outer periphery of the ventilary mixer. a primary air flow rate adjusting means for adjusting the flow rate of primary air introduced into the upstream end of the ventilate mixer; is provided with a movable secondary air flow rate adjusting means, and the primary air flow rate adjusting means includes a primary air door that is movable toward and away from the upstream end opening of the ventilary mixer; and a primary air adjustment handle, wherein the secondary air flow rate adjustment means is slidably supported on the inner wall of the air duct and moves in the axial direction of the ventilary mixer to control the flow path of the secondary air. a removable wall is formed in the air duct near the most upstream portion of the ventilary mixer, comprising a secondary air door to throttle and a secondary air adjustment handle for moving the secondary air door; A primary air conditioning handle and a secondary air conditioning handle are attached to the wall.

[Function] The upstream end of the cylindrical Ventury mixer, that is,
The primary air introduction section is provided with primary air flow rate adjusting means. A portion of the combustion air guided through the air duct is introduced into the ventilate mixer after its flow rate is adjusted by the primary air flow rate adjusting means.
On the other hand, air that has not been introduced into the ventilate mixer (secondary air) is first guided perpendicularly to the outer periphery of the ventilic mixer. That is, the secondary air flows toward the ventilate mixer perpendicularly to the longitudinal direction of the ventilate mixer. The direction of this secondary air is smoothly changed by the flange portion and bending portion provided at the most upstream portion of the ventilate mixer. That is, the secondary air flowing perpendicularly to the longitudinal direction of the ventilate mixer becomes an air flow flowing parallel to the longitudinal direction due to the flange portion and the bent portion. This redirected secondary air then flows along the outer periphery of the ventilic mixer over its entire length, from the top of the ventilic mixer to the most downstream part. The flow rate of the secondary air is adjusted by a secondary air flow rate adjustment means.

[Example] An example of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a diagram showing a radiant wall burner 1 (hereinafter referred to as "burner") as an example of a premixed gas burner of the present invention, which is attached to a furnace wall 2 of an ethylene cracking furnace (not shown).

As shown in the figure, the burner 1 mainly includes a hollow cylindrical ventilate mixer 4 having a flange portion 3 at the upstream end (on the left side in the figure), and a ventilator mixer 4.
A burner chip (crater) 6 which is coaxially connected to the downstream end of the burner chip 6 and has a nozzle 5 facing the inside of the furnace near its extended end, surrounds all of the ventilary mixer 4 and the upstream part of the burner chip 6 in their axial direction. At the same time, an air duct 7 is formed by being bent outward in the radial direction of the ventilate mixer 4 from the vicinity of the flange portion 3 of the ventilary mixer 4;
From a cover material that is installed astride the wall surface 18 removably provided on the above-mentioned bent part and the flange part 3 of the ventilate mixer 4, and can move toward and away from the flange part 3 in the axial direction of the ventilate mixer 4. a primary air flow rate regulating means 9 having a first valve body (primary air door) 8; a secondary air flow rate adjusting means 11 having a second valve body (secondary air door) 10 made of a hollow cylindrical body that can move toward and away from the flange portion 3 in the direction; The fuel injection nozzle 12 is provided on the same axis as the mixer 4 and is configured to supply fuel into the ventilic mixer 4 from the upstream side of the ventilic mixer 4.

The ventilary mixer 4 is threaded at its downstream end and is configured to be screwed onto the upstream side of the burner chip 6.

The burner tip 6 is formed in the shape of a cylinder with a bottom and has approximately the same diameter as the ventilate mixer 4, and has a plurality of nozzles 5 arranged in two rows along the circumferential direction on the peripheral wall near the bottom, that is, near the downstream end, and facing the inside of the furnace. Primary flame nozzle 13
and a primary flame nozzle 13 formed in the shape of a double bottom cylinder.
A secondary air nozzle 17 is provided around and coaxially with the secondary air nozzle 17, the double bottom portion of which serves as a secondary air nozzle 15 facing into the furnace. The upstream end of the secondary air nozzle 17 is inserted into the downstream end of the air duct 7.

The primary flame nozzle 13 forms a primary combustion vortex 52 radially outward from the nozzle 5 of the primary flame nozzle 13 , and the secondary air 48 is supplied to the primary combustion vortex 52 to generate secondary combustion in the secondary combustion zone 53 . configured to burn.

The secondary air nozzle 17 has a nozzle 15 extending radially outward of its cylindrical body 55, as shown in FIG. The rotating blade 56 has a plurality of blades 60 that are slightly inclined in the direction and provided at predetermined intervals. The swirl vane 56 allows the secondary air passing through the secondary air nozzle 17 to move in the direction indicated by the arrow 57.
The secondary air is configured to be inclined in the tangential direction of the secondary air nozzle 17 and supplied radially into the furnace.

The primary flame nozzle 13 also has a ventilary mixer 4 at its upstream portion 58 as shown in FIG.
It is threaded to be screwed into the downstream part of the.

On the other hand, the primary air door 8 is an umbrella-shaped valve body with an opening in the center as shown in FIG. The peripheral end portion is supported by a guide bar 14, and the central portion is supported by a spud holder 16 inserted into the opening. Guide bar 14
One of the air ducts 7 extends outwardly through the wall 18 of the air duct 7, and a primary air conditioning handle 19 is provided at its extending end. By rotating the primary air adjustment handle 19, the primary air door 8 is moved closer to or away from the upstream end opening of the ventilator mixer 4.

The fuel injection nozzle 12 is attached to the wall surface 18 of the air duct 7 and has a connecting part 20 connected to a gas fuel pipe supplied from a fuel supply means (not shown), and a bench from the connecting part 20 into the air duct 7. It consists of a spud holder 16 that continues in the axial direction of the yuri mixer 4, and an orifice spud 21 provided at the tip of the spud holder 16. In addition, a pipe plug 22 is attached to the connection part 20.
is provided.

A downstream portion of the cylindrical secondary air door 10 is fitted into the air duct 7 so as to be movable in the axial direction thereof. Further, a guide bar 24 for moving the secondary air door 10 and a secondary air adjustment handle 25 are attached in this order to the upstream portion thereof. Specifically, one end of the guide bar 24 is attached to the peripheral wall of the secondary air door 10, a substantially central portion is supported by the flange portion 3, and the other end is extended to the outside of the wall surface 18 of the air duct 7, and the guide bar 24 is attached to the peripheral wall of the secondary air door 10. It extends parallel to the axis of 4. A secondary air conditioning handle 25 is attached to the other end of this guide bar 24, and by rotating this handle 25, the secondary air door 10 is moved in the axial direction of the ventilator mixer 4 into contact with the wall of the air duct 7. It is configured to be moved while maintaining airtightness. Secondary air door 10
The outer diameter of the flange 3 of the ventilate mixer 4
are formed to have substantially the same outer circumferential diameter, and when the secondary air door 10 is moved toward the flange portion 3 side, the flow path of the secondary air 48 is narrowed. That is, the throttle valve is configured to operate.

The air duct 7 has an L-shaped cross section, and has a flange 30 connected to an air pipe (not shown) at the upstream end, and an attachment member 32 at the center.
A flange portion 31 connected to the furnace wall 2 via
have. Further, a portion downstream of the flange portion 31 is formed into a flanged cylindrical shape, and is locked together with the flange portion 31 at the flange portion 42, and the ventilary mixer 4 is secured by the cylindrical portion 50.
It surrounds the downstream end of the gas tip 6 and the upstream end of the gas tip 6, and has a tip 33 configured to be inserted into the downstream end of the secondary air nozzle at its downstream end.
Furthermore, the wall surface 18 of the air duct 7 is configured to be detachable from other parts of the air duct 7 using bolts 26 and nuts 27, and as described above, a primary air adjustment handle is provided on this wall surface 18, that is, on the back of the burner 1. 19, a secondary air conditioning handle 25 and a plumbing connection 20 are located. The shape of the wall surface 18 is a disk shape that is slightly larger than the flange portion 3.

The attachment member 32 includes a front plate 34 in the shape of a cylindrical body with a bottom and a flange portion 45, a donut-shaped block insulator 35, a burner block 36, a heater wall plate 37 provided on the outside of the furnace wall 2, and the furnace wall. It consists of an expansion joint 39 installed in the peripheral wall of an opening 38 provided in 2. front plate 3
4 has its bottom 40 connected to the tip 33 of the air duct 7.
The outer periphery of the cylindrical body 44 is in close contact with the inner periphery of the expansion joint 39, and the flange 45 is connected to the furnace through the heater wall plate 37. It is formed so as to be locked on the outside of the wall 2. The donut-shaped block insulator 35 is connected to the tip 33 of the air duct 7 at its inner periphery.
The cylindrical portion 50 of
It is locked in close contact with the burner block 36
has approximately the same shape as the block insulator 35, is provided coaxially with the burner 1, its outer peripheral surface is in close contact with the expansion joint 39, its inner peripheral surface surrounds the burner chip 6, and one end surface is in close contact with the expansion joint 39. is formed so as to be in close contact with the end face of the block insulator 35, and the other end face faces into the furnace.

Next, the operation of the burner 1 constructed and arranged as described above will be explained.

High-temperature (150 to 500°C) combustion air 46 that has undergone heat exchange with exhaust gas (not shown) is introduced from the upstream end of the air duct 7, and a portion (primary air) 47 is sent to the primary air door 8 and the ventilary mixer. It passes through the gap between the flange portions 3 of 4 and enters the ventilate mixer 4. Then, a primary combustion vortex 52 is formed which is mixed with the gas fuel supplied from the fuel injection nozzle 12 and ejected from the injection port 5 of the primary flame nozzle 13. Air that is not introduced into the ventilate mixer 4 at this time first flows perpendicularly to the ventilic mixer 4 as secondary air 48, and then flows to the flange portion 3 at the most upstream part of the ventilic mixer 4 and integrally therewith. After the direction is smoothly changed by the bending part, in the longitudinal direction of the ventilary mixer 4,
That is, it flows rightward (downstream direction) in the drawing along the outer periphery. The secondary air 48 that has reached the lowest downstream area of the ventilator mixer 4 is ejected into the furnace from the nozzle 15 of the secondary air nozzle 17, and is ejected into the furnace from the secondary air combustion zone 5.
3, secondary combustion occurs with the primary combustion vortex 52.

At this time, the primary and secondary air conditioning handles 19,
When 25 is rotated, the primary and secondary air doors 8,1
0 are moved in the axial direction of the ventilate mixer 4, respectively, to adjust the flow rates of the primary and secondary air 47, 48. Specifically, for example, in order to decrease the primary air flow rate, the primary air adjustment handle 19 may be rotated so that the primary air door 8 is brought closer to the flange portion 3 of the ventilary mixer 4.

As is clear from the above description, in the burner 1 of this embodiment, the primary air 47 and the secondary air 4
8 can be adjusted by primary air flow rate adjustment means 9 and secondary air flow rate adjustment means 11, respectively.

Furthermore, since the configuration of these air flow rate adjustment means is simple, highly reliable air flow rate adjustment can be expected.

Furthermore, the air flow rate can be adjusted using the wall surface 1 of the air duct 7.
8. That is, the operation is easy because the primary air conditioning handle 19 and the secondary air conditioning handle 25 are respectively disposed close to the back of the burner 1.

In addition, other parts of the air duct 7 can be attached and detached from the wall surface 18 of the air duct 7, so that the ventilary mixer 4 and the primary and secondary air flow rate adjustment means 9, 11 can be easily removed from the air duct 7. I can do it.

Moreover, since the secondary air 48 flows over the entire length of the ventilic mixer 4 and surrounds the ventilic mixer 4, the secondary air 48 keeps the ventilic mixer 4 warm. In other words, since fuel (low temperature) is mixed into the primary air 47, the temperature of the primary air 47 decreases, but the secondary air 48 heats the ventilary mixer 4 and keeps it warm. This heat retention effect ensures good combustion of the primary air 47.

Furthermore, since the secondary air door slides while being supported by the inner wall of the air duct, there is no need to separately provide a member for guiding the sliding movement of the secondary air door. Also, compared to sliding without any support,
The sliding reliability of the secondary air door is improved.

In addition, the primary and secondary air conditioning handles 19, 25
may be rotated directly manually or by a driving means such as a motor.

[Effect of the idea] In summary, the present invention has the following effects.

(1) The flow rate of primary air and secondary air can be easily adjusted.

(2) Since the direction of the secondary air flowing vertically can be changed smoothly, no stagnation occurs in the subsequent flow of the secondary air. Therefore, good secondary combustion occurs.

(3) Since the secondary air flows over the entire length of the ventilium mixer, the ventilator mixer is kept warm by the secondary air, and therefore the temperature of the primary air flowing inside the ventilator mixer is also maintained, resulting in a good primary air flow. Combustion is guaranteed.

(4) Since the primary air conditioning handle and the secondary air conditioning handle are attached to the same wall, the two handles can be removed from the gas burner at the same time by removing the wall from the air duct.

(5) Since the secondary air door slides while being supported by the inner wall of the air duct, there is no need to separately provide a member for guiding the sliding movement of the secondary air door.
Furthermore, the reliability of sliding of the secondary air door is improved compared to the case where the door slides without any support.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a radiant wall burner as an example of the premixed low NOx gas burner of the present invention installed on the wall of an ethylene cracking furnace;
The figure is a left side view of the main part of FIG. 1, FIG. 3 is a sectional view of the main part of FIG. 1, and FIG. 4 is a view taken along the line A--A in FIG. 3. In the figure, 1 is a radiant wall burner which is a premixed low NOx gas burner, 4 is a ventilary mixer, 6 is a burner chip, 7 is an air duct, 9 is a primary air flow rate adjustment means, 11 is a secondary air flow rate adjustment means, and 46 is a Combustion air, 47 is primary air, 48
52 is a primary combustion vortex, 53 is a secondary combustion zone, and 56 is a swirl vane.

Claims (1)

[Scope of utility model registration request] A part of the air preheated by exhaust gas, etc. is used as primary air and is premixed with fuel in a cylindrical ventilary mixer to form a primary combustion vortex, and the remainder of the air is used as secondary air to form a primary combustion vortex. In a premixed low NOx gas burner that is guided perpendicularly to the outer periphery and then passed along the outer periphery and guided to the secondary combustion zone by a swirl vane provided near the downstream end of the burner chip, a and an air duct for guiding combustion air on the outer periphery, the air duct extending so that the secondary air flows from the most upstream part to the most downstream part of the outer periphery of the ventilary mixer,
A flange part and a bent part are provided at the most upstream part of the ventilium mixer for smoothly changing the direction of secondary air guided perpendicularly to the outer periphery of the ventilary mixer, A primary air flow rate adjusting means for adjusting the flow rate of primary air introduced into the upstream end of the ventilate mixer is provided, and a secondary air flow rate adjustment means, the primary air flow rate adjustment means comprising a primary air door movable toward and away from the upstream end opening of the ventilary mixer, and a primary air adjustment handle for moving the primary air door. a secondary air door, wherein the secondary air flow rate adjusting means is slidably supported on the inner wall of the air duct and moves in the axial direction of the ventilary mixer to narrow the flow path of the secondary air; a secondary air conditioning handle for moving the secondary air door; a removable wall is formed in the air duct near the most upstream portion of the ventilary mixer; A premixed low NOx gas burner characterized in that an air conditioning handle is attached to the wall.