JPH0650165B2 - Swirl flow generator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a swirling flow generation device, and is mainly used in a combustion device and is suitable for giving a swirling force to a fluid such as combustion air. TECHNICAL FIELD The present invention relates to a flow type swirl flow generator.

[Conventional technology]

In a combustion device for oil, gas, pulverized coal, etc., the combustion air is swirled to control the mixing with the fuel, and by appropriate swirling, the flame holding function is enhanced by the formation of a reverse flow region, It is possible to reduce the amount of nitrogen oxides and unburned components by controlling the mixed state of air and air.

That is, reduction of nitrogen oxides and suppression of unburned matter are contradictory. Normally, if mixing of fuel and air is made good to suppress unburned matter, the temperature locally rises. Nitrogen oxides increase and conversely delay the mixing of fuel and air, the amount of nitrogen oxides increases, conversely delaying the mixing of fuel and air decreases the amount of nitrogen oxides. Will increase.

However, if a proper swirl is given to the combustion air, the main flow of the combustion air will flow outward in the vicinity of the burner outlet due to the formation of a backflow region, and the mixing with the fuel will be delayed, resulting in the generation of nitrogen oxides. Suppressed. On the other hand, when you leave the burner,
Since the reverse flow region has disappeared, the main flow of the combustion air is directed to the central portion, and the unburned components generated in the combustion region near the burner can be completely burned. That is, it is very important to give an appropriate swirling force to the combustion air in terms of environmental protection and high-efficiency combustion, and especially when using pulverized coal or the like having poor combustibility as a fuel, the swirling force is delicate. It needs adjustment.

Conventionally, there are a so-called axial flow type and a radial flow type in a swirl flow generation device used in a combustion device or the like. The former axial flow type is
The fluid inlet channel and the outlet channel are cylindrical spaces (that is,
It is a system that exists on the same straight axis of a cylindrical or regular polygonal space) and has a spiral guide vane between the inlet and the outlet to give a swirling force to the passing fluid. On the other hand, the latter radial flow method is a method in which a fluid flows in from a portion corresponding to the side surface of the cylindrical space and flows out from at least one bottom surface of the cylindrical space. And then turns toward the central axis of the cylindrical space toward the bottom surface outlet. At this time, by providing guide vanes in the injection part, a swirling force is applied to the inflowing fluid in the circumferential direction, so that the fluid is first spirally directed to the central part, and then is turned to spirally. It goes to the exit.

FIG. 6 and FIG. 7 show an example of a combustion device provided with a conventional radial flow swirl flow generator. In the figure, the swirl flow generators 24 and 24 ′ are burner ports 11 provided on the furnace wall 2.
It is attached around the central axis of. This example is for a pulverized coal burner. The burner port 11 is provided with a pulverized coal nozzle 8, a secondary air nozzle 9, and a tertiary air flow passage 10 from the center to the outside. It is housed in the wind box 3 together with 24 and 24 '. An auxiliary combustion burner 6 having an impeller 7 is installed in the pulverized coal nozzle 8, and an air dust 4 having a damper 5 is connected to the wind box 3.

The swirl flow generators 24 and 24 'include swirl device side walls 12a and 12b forming a bottom surface of a cylindrical space, a plurality of movable vanes (guide vanes) 25, a rotary shaft 26, links 27 and 30, and an operating shaft 2.
8 and the operation handle 29.

In this type of radial flow type swirl flow generator, the combustion air flows in through the movable blades 25, but when the operation handle 29 is operated to rotate the operation shaft 28, the rotation shaft is rotated via the links 27 and 30. 26 can be rotated. And
When the rotary shaft 26 rotates, the movable blade 25 attached to the rotary shaft 26 also rotates, and as shown in FIG. 8, the angle θ between the tangent 32 of the rotary shaft center circle 31 and the movable blade 25 changes. The inflow direction of the combustion air flowing into the swirl flow generation device can be changed. Further, the change in the angle θ of the movable blades 25 also changes the minimum flow path width between the movable blades. Therefore, if the movable blade angle θ becomes smaller, the inflow direction will approach the tangential direction, the circumferential component of the inflow speed will increase, and the inflow speed itself will also increase significantly, and the swirling force should increase dramatically. belongs to.

[Problems to be solved by the invention]

However, as shown in FIG. 9, a gap 33 exists between the movable blade 25 and the side walls 12a and 12b of the swirl flow generator, so that a part of the fluid leaks. The gap 33 needs to move the movable blades 25 with a power as small as possible, needs to be movable even if the device receives thermal strain due to radiant heat from the furnace wall 2, and further This is a gap that is always present as long as it has a movable blade structure because, for example, the manufacturing cost is increased if the work precision is unnecessarily increased.

As described above, if the movable vane angle θ is reduced to reduce the minimum flow passage width in order to increase the swirling force, the cross-sectional area of the vane portion in the swirling flow generator is reduced, and the area of the gap portion does not change. As a result, the area ratio of the gap portion to the total flow passage area increases. Therefore, the proportion of the leak fluid that does not include the circumferential component increases, and even if the movable blade angle θ is reduced, the expected increase in the turning force cannot be obtained. Moreover, the pressure loss alone has the undesired result of increasing reliably.

In addition, since the plurality of movable blades are linked and moved by the links, the blade angles θ of the individual movable blades are different from each other, which causes uneven flow, and there is play in the link portion. Movable blade 2 even if moved
This causes an inconvenient situation in properly controlling the turning force, such as 5 not following.

It is an object of the present invention to provide a radial flow type swirl flow generation device which eliminates the above-mentioned drawbacks of the prior art, reduces the amount of fluid leak, and can efficiently generate a swirl flow.

[Means for solving problems]

According to the present invention, in the above radial flow type swirl flow generating device, the movable guide vanes are fixed, and at least one of the walls corresponding to the bottom surface of the cylindrical space is a central axis of the cylindrical space. The sliding wall is movable in any direction.

Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

〔Example〕

1 to 3 show an example in which the radial flow type swirl flow generators 1 and 1'according to an embodiment of the present invention are applied to a pulverized coal burner.

In the figure, a burner port 11 is provided on the furnace wall 2, and the burner port 11 is provided with a pulverized coal nozzle 8, a secondary air nozzle 9 and a tertiary air flow passage 10 outward from the center thereof. There is. The secondary air nozzle 9 and the tertiary air flow passage 10 respectively have a radial flow type swirl generator 1,
1'are attached and they are housed in a wind box 3. An air duct having a damper 5 is connected to the wind box 3, and an auxiliary combustion burner 6 to which an impeller 7 is attached is provided in the pulverized coal nozzle 8.

The radial flow type swirl generators 1 and 1'include swirler side walls 12
a, 12b, a plurality of fixed guide vanes 13, a movable side wall (sliding side wall) 14 having a cutout portion through which the fixed guide vane 13 can penetrate, a cylinder 15 connected to the movable side wall 14, Packing 1 provided inside this cylinder 15
6 and an operation rod 17 having one end attached to the cylinder 15 and the other end penetrating the outer wall of the wind box 3.

A cylindrical space is formed between the swivel device side wall 12a and the movable side wall 14, and the movable side wall 14 can be moved in the central axis direction of the cylindrical space between the swivel device side wall 12a and the movable side wall 14 by the operation lot 17. is there.

The plurality of fixed guide blades 13 are usually attached so as to be in contact with the inscribed circle of the tip of the blades, but in some cases, they may have an arbitrary angle with the tangent line of the inscribed circle.

Next, the operation of the radial flow type swirl flow generators 1 and 1'having the above-described configuration will be described.

First, a fluid such as combustion air supplied from the air duct 4 into the wind box 3 is supplied to the swirl flow generators 1 and 1 '.
Then, it passes through the flow passage 18 to reach the tertiary air flow passage 10 and the secondary air nozzle 9, and further passes through the burner port 11 to be ejected into the furnace.

The fixed guide vane 1 is provided at the inlet of the swirl flow generator passage 18.
3 and the fluid that has flowed in here is fixed guide vane 1
The direction of the flow is changed in the direction of the angle of 3 (usually the circumferential direction), and the turning force is given. Therefore, the spiral flow is directed toward the center of the swirl flow generators 1, 1 '. By the way, the side wall of the swirl device is a and the central part of the swirl flow generating device 1,
Since it is connected to the tertiary air flow path 10 or the secondary air nozzle 9 which is the outlet of 1 ', the direction is changed again, and it becomes a spiral flow toward the burner port 11.

Here, the width of the swirl flow generator passage 18 is determined by the operation rod 1
Since the movable side wall 14 can be slid in the axial direction by the operation of 7, the inflow speed of the fluid can be arbitrarily changed, and the turning force can be changed. Also,
Since there is no gap between the fixed guide vane 13 and the side walls 12a and 12b, there is no fluid to leak. Further, since the fixed guide vanes 13 are usually arranged so that the inflow direction of the fluid coincides with the tangential direction of the inscribed circle of the vane tip as much as possible, most of the velocity velocity of the fluid is converted into the swirling force. The efficiency of swirling flow generation is good.

Next, FIG. 4 shows a second embodiment of the present invention. In this embodiment, the packing 2 is provided in the notch 19 provided in the movable side wall 14.
0 is provided. As a result, since the cutout portion 19 can be sealed, the airtightness of the sliding portion can be maintained even if the workability of the cutout portion 19 is poor.

FIG. 5 shows a third embodiment of the present invention, in which the annular block 22 is slid by the operation rod 17 in the groove 23 into which the fixed guide vane 13 can be inserted, so that the flow path 18 of the swirling flow generating device is formed. The width is changed, and the effect is the same as that of the first embodiment.

In addition, although each of the above-described embodiments is an example applied to a pulverized coal burner, it goes without saying that it can be applied to all cases where a swirl flow is required, such as a burner using another fuel or an after-air port.

〔The invention's effect〕

As described in detail above, according to the present invention, in the radial flow type swirl flow generator, the guide vanes are fixed in the most efficient connection direction, and the movable side wall is slid to make the flow path width of the swirl flow generator. Since the turning force can be adjusted by changing
It is possible to eliminate leak fluid that does not contribute to the swirling force found in the use of conventional movable guide vanes, and the angle of the guide vanes is constant. The amount of change in swivel force should be very large without the specified swivel force becoming unachievable due to the increase in short path due to the decrease in the effective vane length by reducing the vane angle of the movable guide vanes. You can Further, it is possible to reduce the deviation of the flow state due to the variation of the blade angle of the movable guide blade. Therefore, when the swirl flow is generated, there is little waste, and fine swivel force control is possible.

[Brief description of drawings]

1 to 3 are views showing an example of a pulverized coal burner provided with a radial flow type swirl flow generating device according to a first embodiment of the present invention. FIG. 1 is a sectional view and FIG. 1 is a sectional view taken along the line AA ', FIG. 3 is a partially enlarged view of a portion B in FIG. 2, and FIGS. 4 and 5 are views showing parts of the second and third embodiments of the present invention. 6 to 9 are views showing an example of a pulverized coal burner provided with a conventional radial flow type swirl flow generator, and FIG. 6 is a sectional view,
FIG. 7 is a sectional view taken along the line CC ′ of FIG. 6, and FIGS. 8 and 9 are partial views. 1, 1 '... Radial flow type swirl flow generator, 3 ... Wind box, 4
...... Air duct, 5 ...... Damper, 6 ...... Auxiliary burner, 8
... Pulverized coal nozzle, 9 ... Secondary air nozzle, 10 ... Tertiary air flow path, 11 ... Burner port, 12a, 12b ...
... Swirl device side wall, 13 ... Fixed guide vanes, 14 ... Movable side wall (sliding side wall), 15 ... Cylinder, 16,20 ... Packing, 17 ... Operation rod, 18 ... Swirl flow generator flow path , 19 ... notch, 21 ... air flow, 22 ... annular block, 23 ... groove.

Claims (1)

[Claims] 1. A cylindrical space having one bottom surface as a wall, the other bottom surface having a fluid outlet flow passage in its center and an outer annular portion as a wall, and the side surface corresponding portion being fluid. In a so-called radial flow type swirl flow generating device in which the inlet flow passage is arranged and guide vanes are provided in the inlet flow passage, the guide vane is fixed and the wall of the wall forming both bottom surfaces of the cylindrical space is fixed. At least one of the walls is a sliding wall that is movable in the direction of the central axis of the cylindrical space.