JPS6143207Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is designed to eliminate the inconvenience of filter clogging due to impurities such as dust and solid objects in the measured fluid, resulting in decreased detection sensitivity and measurement errors. The present invention relates to a filter clogging detection device for a vortex flowmeter, which is capable of issuing an alarm to notify purification or replacement of the filter when the filter reaches the limit.

In general, a vortex flow meter generates a Karman vortex street in the fluid to be measured using a vortex generator installed in a pipe, and detects and counts the vortices of this Karman vortex street using an appropriate means to determine the flow velocity or flow rate. It is configured as follows.

Therefore, the only mechanical component exposed in the pipe is the vortex generator, and its simple structure makes it suitable for measuring the flow rate of gases, liquids, etc. that contain impurities such as dust and solid objects. In addition to being able to
Since the measurement accuracy is extremely high, it has recently become widely practiced.

By the way, regarding the vortex measuring means of this eddy current meter,
The present applicant previously filed Japanese Patent Application No. 52-58443 (Japanese Patent Publication No. 57
-24492 Publication) JP-A-53-143361 (JP-A-55-1989)
-91141 Publication) has been completed, and a sensor like a thermistor can sensitively detect pressure fluctuations caused by the Karman vortex effect of the bias flow in the divided bypass pipe, resulting in an extremely sensitive and highly accurate flow meter. provided the technology.

Since the flow dividing means is used, it is possible to completely eliminate solid objects such as coarse dust in the fluid to be measured that seriously interfere with flow rate measurement. However, it is impossible to avoid mixing in the bias flow. Therefore, it is predicted that a filter that passes the bias flow will inevitably become clogged and tend to gradually lower its output, eventually leading to a state where the output stops.

Such inconveniences can be dealt with by cleaning or replacing the filter, but the problem is how to properly detect or notify when it is time to inspect the filter.

This idea was created by focusing on the points mentioned above, and it detects or notifies filter clogging, prevents inconveniences such as a decrease in Karman vortex detection sensitivity and measurement errors, and ensures proper measurement at all times. To provide a filter clogging detection device in a vortex flowmeter which can be maintained under the same condition.

An embodiment of this invention will be described below with reference to the drawings.

1 is a conduit through which a fluid to be measured flows, and 2 is a vortex generating body disposed in the conduit 1 and having an isosceles triangular cross-sectional shape. Note that the cross-sectional shape can be formed into any desired shape and is not specified in any way. 3 is pipe 1
a bypass pipe with one end open on the upstream side of the vortex generator 2; 4 and 5 are branch pipes that are separated from the bypass pipe 3 at a branch point 6; 7 and 8 are branch pipes of the branch pipes 4 and 5; Both ends of the branch pipes 7 and 8 are provided with two openings 7, a total of four openings 7, on both sides of the upper and lower rear portions of the vortex generator 2.
They are formed as a, 7b, 8a, and 8b. The branch pipes 7 and 8 are provided with sensors S ₂ and S ₁ such as thermistors near the intersections with the branch pipes 4 and 5, respectively. Reference numerals 9 and 10 indicate removable and replaceable filters disposed in the flow branch pipes 4 and 5, each having a different sieve size. Now, if the filter 9 is formed with smaller sieve mesh than the filter 10, the filter 9 will become clogged earlier than the filter 10, and the clogging time of both filters 9 and 10, that is, the dust This results in a difference in adhesion time. 11 and 12 are preamplifiers for sensors S ₂ and S ₁ , respectively, and 13 and 14 are frequency -
A converter 15 such as a current converter or a frequency-voltage converter is a comparator that compares and discriminates the output signals from both converters 13 and 14, and is capable of issuing a deviation alarm. 16 is an alarm signal output terminal;
Reference numeral 17 indicates a changeover switch capable of switching signals from both converters 13 and 14, reference numeral 18 indicates a pulse signal output terminal, and reference numeral 19 indicates a plurality of valves provided at appropriate locations.

With the above configuration, the fluid flowing into the bypass pipe 3 out of the fluid to be measured flowing in the pipe line 1 is
The flow is divided into two at the dividing point 6, passes through the dividing pipes 4 and 5, and further flows into the branch pipes 7 and 8, openings 7a and 7 on both sides of the rear of the vortex generator 2.
It flows back into the pipe line 1 through the channels b, 8a, and 8b.

By the way, when the fluid to be measured flowing through the pipe 1 crosses the vortex generator 2, Karman vortices are generated alternately on both sides of the downstream side of the vortex generator 2.

The formation and separation of Karman vortices that alternately occur on the side surfaces of the vortex generator 2 is due to pressure fluctuations, so the opening 7a, which is the confluence end of the bias flow in the bypass pipe with the pipe line,
It acts as a load change in 7b, 8a, and 8b, and causes a flow velocity change of the bias flow to occur in synchronization with the Karman vortex period, and this flow velocity change is transmitted to the branch pipes 7 and 8, and the respective sensors S ₂ and S ₁ is sensitively detected, preamplifiers 11 and 12, converter 1
3 and 14, an output signal is taken out, whereby the flow rate or flow rate of the fluid flowing in the pipe 1 can be indirectly known.

Although not shown, for example, both sensors
S ₁ and S ₂ each constitute a bridge circuit as a pair of thermistors, and are heated by a constant current power supply with an extremely weak current, so when no fluid is flowing, a flow is generated in the bias flow path. However, when a flow occurs, the thermistor sensor in the bias flow path changes in flow velocity, causing a differential resistance change in the pair of thermistors, so the bridge circuit maintains balance. One cycle of alternating voltage is generated each time a pair of vortices is generated, and by amplifying this, it is possible to obtain an output close to a sine wave that is equal to the frequency of the vortices, and this signal is detected to determine the flow velocity or flow rate. can be measured.

In such flow velocity or flow rate measurement, filters 9 and 10 with different sieve mesh sizes are installed in the branch pipes of the bypass flow path to filter out dust, etc. in the diverted fluid. , gradually accompanied by clogging phenomenon.

However, since the two filters 9 and 10 have different sieve mesh sizes, there can be a difference in the adhesion time of dust.

Furthermore, the deviation alarm 15 can very sensitively detect a decrease in sensitivity due to clogging of the filters 9 and 10.

In particular, it is clear that the filter 9 with a small sieve mesh gets clogged more quickly than the filter 10 with a larger sieve mesh, so there is a risk that the sensor _S2 on the filter 9 side will deteriorate in sensitivity or become undetectable earlier. However, since the sensor S ₁ on the other filter 10 side is still operating normally, it is necessary to close the valves necessary to clean and replace the filter 9. By taking appropriate measures, normal operation can be restored during continuous measurement.

Although one embodiment of this invention has been described above, it goes without saying that this invention is not limited to the above-mentioned embodiment and can be implemented by freely changing the structure.

According to this invention, as mentioned above, filters with sieve meshes of different sizes are arranged in each of the branch pipes of the bypass flow path, and the filters are arranged downstream of the filters in order to differentiate the adhesion time of dust. When there is a difference in the sensitivity of the two sensors and the comparator reaches a certain difference value, an alarm can be reliably generated, so the alarm that reports this abnormal situation can be used to prevent filter replacement. , it has the characteristic that it can completely eliminate measurement errors due to poor sensitivity or decreased sensitivity through purification, and can constantly perform accurate measurements.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional explanatory diagram showing an embodiment of a filter clogging detection device in a vortex flowmeter according to this invention;
FIG. 2 is an explanatory diagram showing the configuration of the main parts of the same. 1... Pipe line, 2... Vortex generator, 3... Bypass pipe, 4, 5... Branch pipe, 7, 8... Branch pipe, S ₁ ,
S ₂ ...Sensor, 9, 10...Filters with different sieve mesh sizes, 15...Comparator.

Claims (1)

[Scope of utility model registration request] A Karman vortex is generated in the measured fluid flowing in the pipe by a vortex generator installed in the pipe, and
A bypass flow path is formed with respect to the pipe line, one end of which is opened on the upstream side of the vortex generator, and the other end is opened on the side surface of the vortex generator, and a sensor disposed in the bypass flow path is configured to detect the generation of the Karman vortex. In a vortex flow meter that measures the flow velocity or flow rate of a fluid to be measured by detecting the
Further, a branch pipe is formed in each of the branch pipes, and a sensor is provided at the intersection between the branch pipe and the branch pipe, and a filter with a different size of sieve mesh is provided in the branch pipe on the upstream side of the sensor. A filter clogging detection device is provided in which the detection signals of the sensors are constantly compared by a comparator, and when a predetermined value is reached, an alarm signal is issued to notify that the filter is clogged.