JP2004191204A - Aperture variable suction nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To instantaneously and freely change an inlet aperture of a suction nozzle, and to restore a constant suction velocity condition again, while maintaining a constant suction flow rate in a measuring instrument under the condition where the suction nozzle is inserted into a flue or a duct, in response to a change in an exhaust gas flow velocity. <P>SOLUTION: In a dust sample collecting measuring instrument provided with this aperture variable suction nozzle of the present invention, the aperture variable suction nozzle communicated with a dust sample measuring instrument and a suction means is inserted into an inside of an exhaust gas passage or the like, the inlet aperture of the aperture variable suction nozzle is changed freely to maintain the constant suction gas flow rate determined by the dust sample measuring instrument and to bring the suction velocity same to the exhust gas flow velocity, and the exhaust gas sucked through the aperture variable suction nozzle is introduced into the dust measuring instrument. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a suction nozzle used for an apparatus that classifies particulate matter (hereinafter, referred to as "dust") in flue gas for environmental protection based on a specific particle size and measures mass concentration. About.
[0002]
[Prior art]
In the measurement of flue gas mass concentration, the method of collecting flue gas at the same speed as the flue gas flow rate was used as the standard, but the specific particle size (PM2.5: 2.5 microns or less in particles suspended in gas) Was not able to be measured automatically. In order to measure the mass concentration of a specific particle size, it is necessary to suction at a constant flow rate and aerodynamically classify. For this purpose, a device having a suction nozzle with a fixed diameter has a constant-speed suction (in this specification, "suctioning the exhaust gas at a speed equal to the flow velocity of the exhaust gas at the same speed" is referred to as "constant-speed suction"). And a device capable of both a constant suction flow rate.
As a solution, an apparatus for changing the diameter of the nozzle has been proposed. As a device for changing the diameter of the nozzle, there has been proposed a method in which a metal thin plate is rounded into a conical shape to form a nozzle, and the area of the apex (nozzle inlet) of the conical shape is changed (for example, Patent Document 1). 1).
[0003]
[Patent Document 1]
JP 2002-340747 A
[Problems to be solved by the invention]
However, in the above-mentioned conventional technology, there are problems that the manufacture is troublesome and that the area of the apex of the cone cannot be accurately grasped and controlled.
An object of the present invention is to provide a variable suction port nozzle that can be easily manufactured and that can be accurately controlled.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a suction nozzle variable nozzle according to the present invention is a suction nozzle for collecting particulate matter in a flue, wherein a conical control cone is provided in the nozzle suction port so as to be able to freely move in and out in the axial direction. Is characterized in that the suction area is variable.
The variable suction port nozzle of the present invention is characterized in that the cross-sectional shape of the nozzle suction port is rectangular and the control cone is wedge-shaped.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG.
FIG. 1 shows an overall configuration of an embodiment of the present invention, in which a suction port variable nozzle 2 is arranged facing a flue 1 for measuring a particle size distribution of dust. The rear part of the variable suction port nozzle 2 is connected to an impactor type classifier 8 via a connection tube 7, and the classifier 8 is connected to a suction pump 9 via an appropriate pipe.
[0007]
FIG. 2 shows a first embodiment of the variable suction port nozzle 2.
The variable suction port nozzle 2 has a circular cross section, and a conical control cone 3 is provided at the entrance so as to be freely inserted and removed in the axial direction. The rear portion of the control cone 3 extends outside the nozzle 2 and is moved back and forth in the axial direction of the nozzle 2 by, for example, a worm / worm wheel 4 and a motor 5. The motor 5 is controlled by the controller 6 shown in FIG.
[0008]
FIG. 3 shows a second embodiment of the variable suction port nozzle 2.
The variable suction port nozzle 2 has a rectangular cross section, and a wedge-shaped control cone 3 is provided at the entrance so as to be freely inserted and removed in the axial direction. The rear portion of the control cone 3 is moved back and forth in the axial direction of the nozzle 2 by a worm / worm wheel 4 and a motor 5 as in the first embodiment.
[0009]
At present, among the fine particles in the atmosphere, particles having a size of 2.5 microns or less (PM2.5) have become a problem, and a measuring instrument has been developed and sold. In this apparatus, the suction flow rate is 16.7 liter / min. With reference to FIG. 4, the insertion / removal distance of the control cone when the exhaust gas velocity in the flue 1 changes at this suction flow rate will be described with reference to FIG. explain.
Now, the suction flow rate Q: 16700 cm ³ / min, the exhaust gas velocity v in the flue 1 v: 6000 cm / min, the length h of the conical portion of the control cone 3: 5 cm, the maximum radius r of the conical portion: 0.5 cm, the nozzle 2 radius R of: 1 cm, a length from the tip of the control cone 3 at the inlet section a-a of the nozzle 2 'h _1, the radius r _1.
[0010]
The suction flow rate Q is represented by the following equation.
_{^{Q = v (πR 2 -πr 1}} 2) = 16700 (1)
r / h = r ₁ / h ₁ (2)
Substituting a numerical value into equation (1) gives
^{_{6000 (3.14-πr 1 2)}} = 16700
∴r ₁ = ｛(3.14-16700 / 6000) 1 / π｝ ^1/2 = 0.337 cm
From equation (2), 0.5 / 0.5 = 0.337 / h ₁
∴h ₁ = 3.37cm
[0011]
Next, determine the h ₁ when v is increased to 6500 cm / min change.
From the above equation (1),
^{_{6500 (3.14-πr 1 2)}} = 16700
_{∴r 1 = {(3.14-16700 / 6500} ) 1 / π} 1/2 = 0.43cm
From equation (2), 0.5 / 0.5 = 0.43 / h ₁
∴h ₁ = 4.3cm
[0012]
From the above calculation results, if the exhaust gas velocity v is changed to 6000 cm / min 6500 cm / min, h ₁ the length from the tip of the control cone 3 at the inlet section a-a of the nozzle 2 'in Figure 4, 3.37Cm It becomes 4.3cm from. Therefore, by drawing the conical portion of the control cone 3 forward by 0.9 cm, suction can be performed at a constant speed while maintaining the suction flow rate Q at 16.7 liter / min.
[0013]
As described above, the cross-sectional area of the entrance aa 'of the nozzle 2 and the cross-sectional area of the control cone 3 intersecting the entrance aa' of the nozzle 2 can be calculated. The relationship between the cross-sectional area of the inlet portion a-a distance h ₁ and nozzle 2 and out of control cone 3 'can be determined numerically. On the other hand, the sectional area of the nozzle 2 is calculated from the constant suction flow rate Q and the exhaust gas velocity v.
Therefore, the controller 6 may control the entrance and exit of the control cone 3 so that the cross-sectional area of the entrance aa 'of the nozzle 2 according to the velocity v of the exhaust gas.
[0014]
【The invention's effect】
According to the suction port variable nozzle of the present invention described in detail above, the suction port variable nozzle is connected to the front stage of the entrance of the classifier, and the suction area of the suction port variable nozzle is maintained at a constant suction flow rate. By changing the flow rate of the exhaust gas in the flue so as to be a constant-velocity suction gas flow rate, a constant-velocity suction state can be secured instantaneously.
Further, according to the present invention, the control cone for changing the cross-sectional area of the suction nozzle is a solid one that is easy to manufacture, and by simply taking in and out of the nozzle, the cross-sectional area of the nozzle entrance can be calculated. Accurate control can be easily achieved.
[Brief description of the drawings]
FIG. 1 is a schematic front view showing an entire configuration according to an embodiment of the present invention.
FIG. 2 is a schematic front view showing a first embodiment of a suction port variable nozzle.
FIG. 3 is a schematic front view showing a second embodiment of the suction port variable nozzle.
FIG. 4 is a schematic diagram for explaining the amount of taking in and out of a control cone when the exhaust gas speed in the flue changes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flue 2 Suction port variable nozzle 3 Control cone 4 Worm and worm wheel 5 Motor 6 Controller 7 Connecting cylinder 8 Classifier 9 Suction pump

Claims (2)

In the suction nozzle that collects particulate matter in the flue, the suction area of the suction port is variable by providing a conical control cone in the nozzle suction port so that it can be freely inserted and removed in the axial direction. nozzle. 2. The variable suction port nozzle according to claim 1, wherein the nozzle suction port has a rectangular cross section and the control cone has a wedge-shaped cross section.

Images