JP3316803B2 - Wet gas flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a positive displacement wet gas flow meter.

[0002]

2. Description of the Related Art An example of a conventional four-chamber positive displacement wet gas flow meter will be described with reference to FIGS. This example is disclosed in Japanese Patent Application No. 7-43065 filed on March 2, 1995 and Japanese Patent Application No. 7-133595 filed on May 31, 1995 by the same inventor as the present inventor. It is.

As shown in FIG. 12, the displacement type wet gas flow meter has a casing 200 and a rotating drum 210 rotatably disposed inside the casing 200. A partition plate 201 is provided inside the casing 200.
1, the interior is divided into a front room 202 and a rear room 203. A blowing pipe 207 is further provided in the casing 200, and one end of the blowing pipe 207 is disposed in the front chamber 202 and the other end is disposed in a measuring chamber in the rotating drum 210. At the top of the casing 200, an inlet 204 and an outlet 205 for metering gas are provided, respectively, and the front chamber 202
And the rear room 203. The front end (the right end in the figure) of the shaft 212 of the rotating drum 210 actually extends further to the front counter portion (pointer).

A liquid 209, usually water, is sealed in the casing 200 at a height of about 3/5, and a rotary drum 210 is immersed in the liquid. The liquid level during gas measurement is
The height is higher in the order of the front chamber 202, the measuring chamber of the rotating drum 210, and the rear chamber 203. That is, the rear chamber 203 in contact with the atmospheric pressure
Is the highest, and the liquid level of the front chamber 202 in contact with the test gas is the lowest. The liquid level in the rotating drum 210 is configured to be always constant.

[0005] The metered gas entering from the inlet 204 is
2. It flows through the blowing pipe 207, the measuring chamber of the rotating drum 210, the rear chamber 203 and the outlet 205. As a result, the rotating drum 210 rotates, and the gas captured in the measuring chamber of the rotating drum 210 is replaced by the liquid 209 and is sequentially discharged. Gas flow meters include 1L type, 10L type, etc., depending on the volume measured per rotation of the rotating drum.
The conventional example shown in FIGS. 12 and 13 is a 1L type.

The structure of the rotating drum 210 will be described with reference to FIG. The rotating drum 210 has a cylindrical drum body 21.
1, a drum 212 having a central shaft 212 and a hole 213A
13, drum washers 214, 215 and partition disk 216,
217 and four blades 221, 222, 223, and 224. The four blades are connected to the inner surface of the drum body 211. On both sides of the four blades, a partition disk 216,
217 are mounted, and washers 214 and 215 are mounted on the partition disks 216 and 217. Drum washer 214,
The shaft 212 is inserted into the hole 215. A drum cover 213 is mounted on the front room 202 side.

Referring to FIG. 14 to FIG.
The structure of 222, 223, and 224 will be described. The four blades have the same shape, and one of them will be described here.
As shown in the perspective view of FIG.
21A, an inlet-side blade 221B, a partition 221C, an outlet-side blade 221D, and an outlet 221E. The outlet 221E is provided with a projection 221F for preventing bubbles when discharging the measured gas. FIG. 15 shows the blade 2
21 is a developed view of FIG. 21 showing a member obtained by cutting a blade portion from a flat plate.

The cutout member is bent along the first and fourth boundary lines 221a and 221d, thereby forming an inlet 221A and an outlet 221E, and along the second and third boundary lines 221b and 221c. By bending the inlet blade 221B and the partition 2
21C and the outlet side blade part 221D are formed.

FIG. 16A is a view of the blade 221 as viewed along the axis 212, and a semicircular concave portion is formed around the axis 212. FIG. 16B is a view of the blade 221 viewed from a line perpendicular to the axis 212 (radial direction perpendicular to the central axis of the partition 221C), and the inlet 221A and the outlet 221E have the inlet-side blade 221B and the outlet-side blade, respectively. Part 221D
Is shown outwardly inclined with respect to.

FIG. 17 shows four measuring chambers 221, 222, 2
Drive torques 221T, 222 acting on 23, 224
T, 223T, 224T, positive and negative drive torque T2,
5 shows T3 and a driving torque T1 acting on the rotating drum.
Here, the positive drive torque T2 is a torque due to the pressure of the metered gas acting in the positive direction of the liquid level, and the negative drive torque T3
Is a torque due to the pressure of the metering gas acting in the negative direction of the liquid level, and both act to drive the rotary drum in the positive direction.

The positive driving torque T2 is applied to the four measuring chambers 22.
1, 222, 223, 224 is the sum of the positive driving torques acting on the four measuring chambers 22.
1, 222, 223, and 224, and the sum of the absolute values of the two is the driving torque T1 acting on the rotating drum.

The driving torque acting on each measuring chamber fluctuates in a cycle corresponding to one rotation of the rotating drum. The drive torque T1 acting on the rotating drum fluctuates periodically in a sinusoidal manner, and has four periods corresponding to four measuring chambers during one rotation.

[0013]

The conventional wet gas flow meter is called a four-chamber type because it has four measuring chambers formed by four blades. In a four-chamber gas flow meter, 4
The flow rate of the test gas is continuously measured by sequentially capturing and replacing the gas with the two measurement chambers. However, the provision of the four measuring chambers causes fluctuations in the driving torque and the measuring volume of the rotating drum.
This fluctuation appears as approximately four periodic fluctuations during one rotation of the rotating drum.

An object of the present invention is to reduce fluctuations or fluctuations in the measurement volume of a conventional four-chamber wet gas flow meter.

[0015]

According to the present invention, a casing, a partition plate for dividing the interior of the casing into a front chamber and a rear chamber, a rotary drum rotatably disposed inside the casing, and the casing In a wet gas flow meter having a liquid filled therein, the rotating drum is provided on the front chamber side, with a cylindrical drum cylinder, five blades mounted on a circumferential inner surface of the drum cylinder. Drum cover, and a pair of washers arranged on both sides of the five blades,
And a shaft mounted on the washer.

Therefore, according to the present invention, the fluctuation or fluctuation of the measuring volume during one rotation of the rotary drum is reduced.

According to the invention, in a wet gas flow meter, the ratio of the outer diameter of the rotary drum to the axial dimension between the inlet and outlet blades that determines the metering volume of the rotary drum is greater than 2; Less than 3. The ratio of the outer diameter of the rotary drum to the axial dimension between the inlet and outlet blades that determines the metering volume of the rotary drum is 2.
It is larger than 5 and smaller than 2.8.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a gas flow meter according to the present invention will be described with reference to FIG. As described above, the gas flow meter has a capacity of 1 L depending on the measured volume per rotation of the rotating drum.
Type, 10L type, etc., but the gas flow meter of this example is a 1L type. Hereinafter, only the rotating drum of the gas flow meter of the present embodiment will be described. The structure other than the rotating drum, that is, the structure of the casing, the partition plate, the blow pipe, the front chamber, the rear chamber, and the like may be the same as the structure of the conventional gas flow meter described with reference to FIG. Omitted.

The rotary drum 10 of this embodiment has a cylindrical drum body 11, a shaft 12, a drum cover 13, a drum washer 14,
5, partition disks 16, 17 and five blades 21, 22, 2,
3, 24, and 25. The five blades are the drum shell 11
Is connected to the inner surface of the circumference. On both sides of the five blades,
The partition disks 16, 17 are mounted, and the partition disks 16, 1
Drum washers 14 and 15 are mounted on 7. The shaft 12 is inserted into holes of the drum washers 14 and 15. A drum cover 13 is mounted on the front room side.

As shown in FIG. 1B, the height of the rotary drum 10, that is, the outer diameter is D, and the thickness is B. Here, the thickness B of the rotating drum 10 is a dimension in the axial direction of a portion that determines the measured volume of the five blades. According to this example, the ratio D / B of the outer diameter D to the thickness B of the rotating drum is smaller than that of the conventional four-chamber wet gas flow meter. In the present example, this ratio D / B is at least less than 3.3. Preferably this ratio D / B
Is greater than 2.5 but less than 2.8.

That is, the rotary drum of this embodiment has a shape longer in the axial direction than the rotary drum of the conventional four-chamber wet gas flow meter. Thus, in the present example, the analysis by the inventor has revealed that since the shape of the rotating drum is long in the axial direction, fluctuations or fluctuations of the driving torque and the measured volume can be reduced.

In the drawing, a line LL is a liquid surface, and a line TL is a gas penetration water level. The gas penetration water level TL is represented by a line connecting the outlet end 21a of one blade 21 and the inlet end 25e of the next blade 25, as shown in FIG. 1A. Liquid level H
LL (the height from the central axis OO of the shaft 12 to the liquid level LL) must be at least greater than the gas penetration water level height HTL (the height from the central axis OO of the shaft 12 to the gas penetration level TL). No. When the liquid level height HLL becomes smaller than the gas penetration water level height HTL, the measuring chamber penetrates the inlet and the outlet, and the pressure in the measuring chamber becomes equal to the pressure of the outside air. Accordingly, the driving torque acting on the measuring drum becomes zero, and gas measurement becomes impossible.

When the liquid level height HLL is increased, the volume of the measuring chamber is reduced, and the driving torque acting on the measuring drum is reduced. The liquid level height HLL is set slightly higher than the penetration water level height HTL in consideration of vibration of the liquid level in the drum.

Referring to FIGS. 2 to 4, the blades 21, 22,
The structures of 23, 24 and 25 will be described. The five blades have the same shape, and one of them will be described here. As shown in the perspective view of FIG. 2, the blade 21 includes an inlet 21A, an inlet-side blade 21B, a partition 21C, and an outlet-side blade 21D.
And an outlet 21E. The outlet 21E is provided with a projection 21F for preventing air bubbles.

FIG. 3A is an exploded view of the blade 21 and shows a member obtained by cutting the blade from a flat plate. By bending the cutout member along the second and third boundary lines 21b and 21c, an inlet-side blade 21B, a partition 21C, and an outlet-side blade 21D are formed. By bending along the first and fourth boundary lines 21a and 21d, an inlet 21A and an outlet 21E are formed. FIG. 3B shows the bending angles of the inlet 21A and the outlet 21E. FIG. 4A is a view of the blade 21 viewed from the axial direction,
FIG. 4B is a sectional view thereof.

Referring to FIGS. 5 and 6, the performance of the five-chamber type flow meter according to the present invention will be described in comparison with three-chamber type, four-chamber type and six-chamber type flow meters. Each of these meters is of the 1L type. The horizontal axis of each graph in FIGS. 5 and 6 is the number of measuring chambers, that is, the number of blades. FIG. 5A is a graph of the pressure receiving area of the gas flow meter,
FIG. 5B is a graph of the driving torque acting on the rotating drum. Increasing the number of weighing rooms from 3 rooms to 5 rooms,
Although the pressure receiving area and the driving torque increase, the five-chamber type and the six-chamber type are substantially equal.

FIG. 6 is a graph of the measured volume of the gas flow meter. Increasing the number of measuring chambers increases the measuring volume. However, even if the number of measuring chambers is increased from five to six, the rate of increase in the measuring volume is small. To increase the number of weighing chambers, it is necessary to increase the number of blades. Increasing the number of blades complicates the process of processing and assembling the blades, and has a negative factor of increasing the submersion resistance of the blades. Furthermore, a gas flow meter with five metering chambers is therefore most efficient.

The pressure receiving area of the five-chamber gas flow meter of this embodiment will be described with reference to FIGS. FIG. 7 shows the pressure receiving areas 21S and 2S of the respective measuring chambers of the five-chamber gas flow meter of this example.
The change of 2S, 23S, 24S, 25S is shown. The pressure receiving area may be considered as the area of the liquid surface in each measuring chamber. This graph includes the pressure receiving area at the dead center.

The dead center will be described with reference to FIG. The dead point refers to a state in which the driving torque does not act on the rotating drum for one measuring chamber. As shown in FIG. 8A, five blades 21, 22, 23, 24, 2
It is assumed that 5 is cut by the liquid level LL. As shown in FIG. 8B, when the first measuring chamber 21 is disposed above, the rotation angle of the rotating drum is set to zero. As shown in FIG. 8C, when the rotation angle of the rotating drum reaches 42.13 degrees, the dead center starts, and further rotates 6.14 degrees, and the rotation angle becomes (42.
13 + 6.14), the dead point ends.

The angle range of the dead center (6.14 degrees) is determined by the difference between the liquid level height HLL and the through water level height HTL. The larger the difference between the liquid level and the penetration water level, the larger the angle range of the dead center, and the smaller the difference, the smaller the angle range of the dead point.

The change in the liquid level will be described with reference to FIG. Each figure in FIG. 9 shows a cross section of the rotary drum of the five-chamber gas flow meter of the present example, which is cut by a plane including the liquid level.
The liquid level in each measuring chamber represents the pressure receiving area. The driving torque for the rotating drum generated by each measuring chamber is expressed by the following equation.

[0032]

## EQU1 ## T = ΔP × S × r

Here, ΔP is the pressure loss, S is the pressure receiving area of the measuring chamber, and r is the distance from the center of the rotating drum to the position of the center of gravity of the pressure receiving area. What is necessary is just to add the drive torque by all the measuring chambers to the drive torque of a rotary drum.

FIG. 10 shows the driving torque acting on the measuring chamber and the rotating drum of the five-chamber wet gas flow meter of the present invention. The driving torques 21T, 22T, 23T, 24T, 25T acting on the respective measuring chambers 21, 22, 23, 24, 25 fluctuate in a cycle corresponding to one rotation of the rotary drum. The driving torque T1 acting on the rotating drum changes in a sinusoidal waveform having five periods corresponding to five measuring chambers during one rotation of the rotating drum.

Referring to FIG. 11, the driving torque of the rotary drum of the five-chamber wet gas flow meter of this embodiment is compared with the driving torque of the rotary drum of the conventional four-chamber wet gas meter. In this example, the deviation of the fluctuation of the driving torque acting on the rotating drum (the deviation of the maximum value from the average value) is 7.3%, but in the conventional example, the deviation is 17.9%. Therefore, in this example,
As compared with the conventional four-chamber wet gas meter, the fluctuation of the metering volume can be made smaller.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various other examples are possible without changing the gist of the present invention. It will be easily understood.

[0037]

According to the gas flow meter of the present invention, there is an advantage that fluctuation or fluctuation of the driving torque and the measuring volume during one rotation of the rotary drum is reduced.

[Brief description of the drawings]

FIG. 1 is a view showing the structure of a rotary drum of a five-chamber wet gas flow meter according to the present invention.

FIG. 2 is a view showing a structure of a blade of a rotary drum of a five-chamber wet gas flow meter according to the present invention.

FIG. 3 is a development view of blades of a rotary drum of the five-chamber wet gas flow meter of the present invention.

FIG. 4 is a perspective view of blades of a rotary drum of the five-chamber wet gas flow meter of the present invention.

FIG. 5 is a diagram showing the performance of a five-chamber wet gas flow meter of the present invention.

FIG. 6 is a diagram showing the performance of the five-chamber wet gas flow meter of the present invention.

FIG. 7 is a diagram showing pressure receiving area characteristics of a five-chamber wet gas flow meter of the present invention.

FIG. 8 is an explanatory diagram for explaining a dead point of the five-chamber wet gas flow meter of the present invention.

FIG. 9 is an explanatory diagram for explaining a pressure receiving area and a driving torque of the five-chamber wet gas flow meter of the present invention.

FIG. 10 is a view showing a driving torque characteristic of the five-chamber wet gas flow meter of the present invention.

FIG. 11 is a diagram showing the variation rate of the driving torque of the conventional five-chamber wet gas flow meter according to the present invention.

FIG. 12 is a view showing the structure of a conventional four-chamber wet gas flow meter.

FIG. 13 is a view showing a development structure of a rotary drum of a conventional four-chamber wet gas flow meter.

FIG. 14 is a view showing a structure of a blade of a rotary drum of a conventional four-chamber wet gas flow meter.

FIG. 15 is a view showing a development structure of blades of a rotary drum of a conventional four-chamber wet gas flow meter.

FIG. 16 is a view showing blades mounted on a rotating drum of a conventional four-chamber wet gas flow meter.

FIG. 17 is an explanatory diagram for explaining a driving torque of a measuring chamber and a rotating drum of a conventional four-chamber wet gas flow meter.

[Explanation of symbols]

10 ‥‥ rotating drum, 11 ‥‥ drum body, 12 ‥‥
Shaft, 13mm drum cover, 14,15mm washer,
21 ~ 25 ‥‥ blade, 200 ‥‥ casing, 2
01 ‥‥ partition, 202 ‥‥ front room, 203 ‥‥ rear room, 204 ‥‥ entrance, 205 ‥‥ exit, 207 ‥
‥ Suction pipe, 209 ‥‥ liquid, 210 ‥‥ rotating drum, 211 ‥‥ drum shell, 212 ‥‥ shaft, 213
{Drum cover, 214,215} Washers, 22
1-224 ‥‥ feather

Claims (3)

(57) [Claims] 1. A casing, a partition plate for dividing the inside of the casing into a front chamber and a rear chamber, a rotary drum rotatably disposed inside the casing, and a liquid filled in the casing. In a wet gas flow meter,
The rotary drum includes a cylindrical drum body, five blades mounted on a circumferential inner surface of the drum body, a drum cover provided on the front chamber side, and both sides of the five blades. A wet gas flow meter, comprising: a pair of washers; and a shaft attached to the washer. 2. The wet gas flow meter according to claim 1, wherein the ratio of the outer diameter of the rotary drum to the axial dimension between the inlet blade and the outlet blade that determines the metering volume of the rotary drum is greater than two. Wet gas flow meter characterized by being smaller than 3.3. 3. The wet gas flow meter according to claim 1, wherein a ratio of an outer diameter of the rotary drum to an axial dimension between an inlet blade and an outlet blade that determines a metering volume of the rotary drum is 2.5. A wet gas flow meter characterized by being larger than 2.8.