JPH0212601Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Field of the invention The invention relates to a float-type density meter, and more specifically, uses a strain gauge-type load cell (hereinafter referred to as a load cell) as a load measuring means.
This invention relates to a rotary densitometer that can measure density while calibrating zero point fluctuations.

(b) Prior Art As a device for on-line measuring the density and concentration of liquids during chemical processes, etc., a float-type densitometer is widely used because it is the simplest and provides a reasonable degree of accuracy.

However, there are inherent problems such as the influence of the dynamic pressure of the liquid and dirt due to the accumulation of deposits on the float.

In addition, as means for detecting gravity and buoyancy acting on the float, a detection section made of a magnetic material is usually provided at the top of the float, and the vertical movement of the detection section is electromagnetically detected, or an optical sensor detects the upper position of the float. However, the accuracy is not sufficient to detect minute changes in the density of the liquid itself, and there is a desire for a highly accurate float-type density meter. Furthermore, in many float-type density meters, the float does not come into contact with anything other than the liquid, and it is necessary to use a float that is appropriate for the density range of the liquid to be measured. There was also a problem.

(c) Point of view The inventors of the present invention have overcome the various problems mentioned above,
As a result of intensive research into a high-precision rotary density meter that can measure liquid density online, we decided to incorporate a mechanism that applies the difference between the gravity moving on the float and the buoyant force to the load cell as a load, and calibrates zero point fluctuations. We discovered that density measurement can be performed with high precision over a long period of time, and arrived at the present invention.

(d) Purpose of the invention The main purpose of the invention is to provide a high-precision rotary density meter, and the purpose of the invention is to provide a high-precision and wide-range density meter using ordinary load cells, amplifiers, constant voltage power supplies, etc. An object of the present invention is to provide a float-type densitometer that enables density measurement.

(E) Structure of the invention The purpose of the invention described above is to provide a liquid supply/drainage control means for the liquid to be measured and a strain gauge type load cell in a float-type density meter that measures the density of liquid from the buoyancy of a float suspended in the liquid to be measured. This is achieved by a float-type density meter equipped with a loading change mechanism between the reference weight and the float, and a calculation means for the output signal of the load cell.

(f) Specific description of the configuration One embodiment of the float type densitometer according to the present invention will be described in detail based on the drawings.

FIG. 1 illustrates the main parts of the float type density meter of the present invention when it is incorporated into a process.

The measurement liquid is flowing through pipes 1 and 2, and in order to flow the measurement liquid into the tank 3, the drain valve 5 is closed, the liquid supply valve 4 of pipe 1 is opened, and the opening degree of the bypass valve 6 of pipe 2 is narrowed. The tank 3 is filled with the measuring liquid to a required level, and the overflowing liquid is discharged from the pipe 7. Next, the bypass valve 6 is fully opened and the liquid supply valve 4 is closed to stabilize the liquid level in the tank 3. A float 8 is attached to the tank 3 so as to hang down from a float hanging fitting 9, and the float hanging fitting 9 is loaded on a support stand 12 fixed to a rod 11 connected to a load cell 10, so that the weight of the float 8 and the buoyant force are combined. The differential load is applied to the load cell 10, and the strain generated in the load cell 10 is transmitted to the amplifier 13 as an electric signal, and sent to the arithmetic and control unit 14 of the microcomputer, where it is stored and processed to calculate the density of the liquid to be measured in the tank 3. Measure.

Here, loading and unloading of the float hanging fitting 9 onto and from the support base 12 is performed by vertically moving an arm 15 with one end fixed in position.

On the other hand, an arm 18 with one end fixed in position is moved up and down in order to load or unload a reference weight 17 for calibrating the fluctuation of the zero point on a support stand 16 fixed to the rod 11. The above-mentioned vertical movement of the arms 15 and 18 is carried out by the loading changing mechanism described below so that the float suspension fitting 9 and the reference weight 17 are not simultaneously loaded or unloaded on the rod 11.

A cam 19 held between the arms 15 and 18 is rotated by a motor 20, and when the elongated portion of the cam 19 joins the arms 15 and 18, the arm 15
is separated from the float hanging fitting 9, and the float hanging fitting 9 is loaded on the support stand 12. At the same time, the arm 18 loads the reference weight 17, and the reference weight 17 leaves the support stand 16, so that the rod 11 is loaded with the float. The load acting on the load cell 8 is applied and transmitted to the load cell 10.

In addition, in order to update the measured liquid in the tank 3, the drain valve 5
This is performed by opening the liquid supply valve 4 while keeping it closed, throttling the bypass valve 6, and after a certain period of time, opening the bypass valve 6 and closing the liquid supply valve 4. During this time, density measurement is stopped.

In this way, the density of the liquid in the tank 3 is measured. When the density measurement reaches the number of times set in the microcomputer, the motor 20 rotates and the rectangular part of the cam 19 is connected to the arms 15 and 18. The motor 20 stops in the joined state. At this time, arm 1 is being pulled upward by spring 21.
5 loads a float hanging fitting, and the float hanging fitting 9 separates from the support stand 12, and the arm 18 separates the reference weight 17, and the reference weight 17 is loaded on the support stand 16, so that the rod 11 is The load of the reference weight 17 is applied, and this load is transmitted to the load cell 10 and stored in the arithmetic and control unit 14 as a reference value.

A cam 22 different from the cam 19 is fixed to the rotating shaft of the motor 20, a micro switch 23 is provided on the cam 22 to make contact or non-contact, and the electric signal of the micro switch is sent to the control calculation device 14. The rotation of the cam 19 is controlled.

The reference value determined by the load measurement using the reference weight 17 is determined by the load cell 10 and amplifier 13 of this measuring device.
This is to calibrate zero point fluctuations caused by changes in characteristics due to environmental temperature, humidity, etc. or minute changes in voltage from a constant voltage power supply.

Therefore, the subsequent density measurements are calculated by the arithmetic and control unit 1
In step 4, all calculations are calibrated using the above reference values.

Calibration of zero point fluctuation by replacing the float hanging fitting 9 and the reference weight 17 on the rod 11 connected to the load cell 10 can be set to an arbitrary frequency depending on the environmental conditions of the installation location of the device of the present invention, the purpose of measurement, etc. be able to.

It is preferable that the weight of the reference weight 17 is approximately half the weight of the float 8, but if the weight of the float 8 is relatively small, the reference weight 17 may be omitted and only the float hanging fitting 9 may be loaded and unloaded. can.

The temperature of the liquid to be measured in the tank 3 is detected by the temperature detection end 24 and sent to the arithmetic and control unit 14 via the amplifier 25, where the temperature of the measured density value is corrected.

Further, a nozzle 26 for cleaning the float 8 is provided in the tank 3. The cleaning operation of the float 8 is performed in the following manner based on electrical signals from the arithmetic and control unit 14. After the measurement liquid in the tank 3 is discharged from the drain valve 5, the cleaning valve 27 is opened and water or warm water is sprayed onto the float 8 from the nozzle 26.

In this embodiment, the arms 15 and 1 are rotated by the rotation of the cam 19 as means for changing the loading of the float hanging fittings 9 and the reference weight 17 onto the supports 12 and 16.
Although the mechanism for vertically moving the float 8 is shown as an example, any mechanism may be used as long as it can load and unload the float suspension fitting 9 and the reference weight 17 onto and from the supports 12 and 16, such as a solenoid system using electromagnetic action, an air mechanism, etc. Alternatively, a cylinder system using hydraulic pressure, a rack and pinion system, etc. may be adopted.

(G) Functions and Effects The float-type density meter of the present invention incorporates a mechanism for replacing the float suspension with the reference weight, which allows for effective calibration of fluctuations in the zero point, resulting in high performance and high cost. Density can be measured with high precision and efficiency using ordinary inexpensive load cells, amplifiers, constant voltage power supplies, etc. For example, when used online in a process, it is possible to It is possible to continuously measure density with high accuracy over a long period of time without being affected by fluctuations.

The float-type density meter of the present invention measures liquids with a wide range of density levels with a single float because the float is always suspended from the float hanging fitting, and by replacing the float it is possible to measure liquids with a wide range of density levels. It can also be measured for liquids.

Furthermore, the float does not come into contact with the inner wall of the tank or swing, and there are no problems such as damage to the float or occurrence of measurement errors.

Furthermore, the float-type density meter of the present invention can also compensate for temperature changes in the liquid to be measured, and can always measure density at a reference temperature, as well as compensate for changes in volume due to expansion and contraction of the float. It is possible.

In addition, since the float is automatically cleaned of any deposits as necessary, it is possible to perform stable continuous measurements over a long period of time even with liquids that tend to have deposits on the float.

The float-type density meter of the present invention controls the reloading mechanism, feeding and discharging of the measuring liquid into the tank, washing the float, etc. using a microcomputer arithmetic control device, and also controls the load measurement of the float and reference weight acting on the load cell. In addition, the temperature measurement value of the measurement liquid is processed in the arithmetic and control unit, and is displayed on the display device as a zero point calibrated and temperature-compensated density measurement value, and printed out, which eliminates the need for maintenance and inspection during online measurement of the process. It is possible to carry out long-term automatic measurements unmanned.

[Brief explanation of the drawing]

FIG. 1 shows an outline of the float-type density meter of the present invention, and FIG. 2 shows a flowchart of calculation and control processing by a microcomputer calculation and control unit. 1, 2, 7...pipe, 3...tank, 4...liquid supply valve, 5...drain valve, 6...bypass valve, 8...float, 9...float suspension fitting, 10...load cell ,1
1... Rod, 12, 16... Support stand, 13, 2
5...Amplifier, 14...Arithmetic control device, 15,1
8... Arm, 17... Reference weight, 19, 22...
Cam, 20...Motor, 21...Spring, 2
3...Micro switch, 24...Temperature detection end,
26...Nozzle, 27...Washing valve.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a float-type density meter that measures the density of a liquid from the buoyancy of a float suspended in the liquid to be measured, means for controlling the supply and drainage of the liquid to be measured, and a reference weight to a strain gauge-type load cell. A float-type density meter comprising a loading change mechanism between the load cell and the float, and a calculation means for the output signal of the load cell. (2) The float-type density meter according to claim 1, in which the loading change mechanism comprises a mechanism for moving the arm up and down by rotation of a cam, and means for controlling the rotation of the cam. (3) The float-type density meter according to claim 1, which is provided with means for cleaning the float. (4) The float-type density meter according to claim 1, which is provided with a means for correcting the temperature of the liquid to be measured.