JPS5921498B2 - concentration measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a concentration measuring device for measuring the concentration of suspensions such as sewage and industrial wastewater, and particularly to a concentration measuring device for measuring the concentration of suspensions by eliminating wasted defoaming time. This invention relates to a concentration measuring device that measures accurately.

Conventionally, methods for measuring the concentration of suspensions include radiation method,
There are light beam type and ultrasonic type, but either method cannot accurately measure the concentration if air bubbles are included in the suspension.

For example, with the radiation type, the presence of air bubbles results in a measurement value that is lower than the actual concentration, while with the light beam type or ultrasonic type, the presence of air bubbles improves the transmittance and results in a measurement value that is higher than the actual concentration. Measured values are obtained. Therefore, none of the measuring means can accurately measure the concentration without any errors. This error is due to the presence of air bubbles in the suspension. Conventionally, a timer and pressurizing pump were installed to eliminate these air bubbles, and the timer set the pump operation time, and the pump was pumped during that time. is operated to perform a defoaming operation (Japanese Patent Application Laid-Open No. 51-35392).

However, with this defoaming means, the operating time is determined based on human intuition while taking into consideration the properties of the suspension, and for this reason, there is a difference between the defoaming time and the defoaming rate of the bubbles as shown in Figure 1. A relationship like this arises.

That is, if the sample contains fine air bubbles, the air bubbles are easily dissolved, so that it exhibits a defoaming rate characteristic like E1.
Therefore, with such a sample, there is plenty of time for defoaming, and the waiting time until concentration measurement is long, resulting in waste. E2
In the case of the defoaming rate characteristic shown in (a), the time for dissolving the bubbles and the time for defoaming exactly match, so that the above-mentioned wasted time is eliminated. In the case of the defoaming rate characteristic of E3, the defoaming time is a little short and the concentration is measured with bubbles remaining, resulting in measured values with errors. In the case of E4, this tendency is even more pronounced than in E3, so errors occur significantly. Therefore, as is clear from the above-mentioned defoaming rate characteristics, the defoaming time differs significantly depending on the bubble content state of the bubbles in the suspension. Therefore, in order to ensure a uniform defoaming time, measures are taken such as applying a very large pressurizing pressure to the suspension and providing a sufficient margin for the defoaming time. However, as in the former case, even if the pressure is increased, there will be variations in the defoaming rate unless the bubble content is uniform, and in the latter case, there is a drawback that concentration measurement must be done knowing wasted time. .

The present invention provides a concentration measuring device that knows when defoaming is complete regardless of defoaming time as described above, eliminates wasted time, and efficiently and accurately measures the concentration of a suspension.

That is, the device of the present invention includes a signal change detection circuit that detects a change in the concentration signal output from a concentration detector equipped with a deaerator, and a signal change detection circuit that holds the concentration signal with a detection signal of zero change in the concentration signal output from this circuit. A sample hold circuit outputs a concentration signal, and a control section receives a detection signal of zero change in the concentration signal from the signal change detection circuit and outputs a degassing completion signal, and The concentration of the degassed suspension is measured while the deaeration is performed, and the measured concentration signal is sent to the signal change detection circuit, which detects the deaeration by the deaeration operation of the concentration detector equipped with the deaeration device. This detection signal of zero concentration signal change is supplied to the sample hold circuit and the control section, which detects that the air bubbles in the suspension have been extinguished and the change in the concentration signal has become zero.

This sample hold circuit receives a detection signal of zero change in the concentration signal and samples and outputs the concentration signal of the suspension.Meanwhile, the control section receives a detection signal of zero change in the concentration signal and outputs the sampled concentration signal of the suspension. A degassing end signal is sent to the detector to end the degassing. An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 10 denotes a distribution pipe through which the suspension flows, and a concentration meter detector 11 with a deaerator is installed at a required position on this pipe 10. This piping 10 and detector 11
Although not shown, they are connected via a valve and communicate with each other by opening the valve. Reference numeral 12 denotes a control unit that controls the concentration meter detector 11 with a deaerator.

The control unit 12 sequentially sends a sample filling command into the detector 11, a degassing start command, a degassing end command, a concentration measurement command, a sample discharge command, etc. to the detector 11.
1. However, this degassing completion command is issued in response to a degassing completion signal obtained by actual measurement of the sample, as will be described later. Therefore, the deaeration time is not uniformly determined as a fixed time as in the past. Therefore, the deaerator-equipped concentration meter detector 11 repeatedly performs sample filling, deaeration measurement, and sample discharge in response to commands from the control section 12. Further, this detector 11 is configured to continuously measure the concentration while degassing and continuously supply the measurement signal to the connected signal converter 13. This signal converter 13 includes a differential circuit 1 which is a signal change detection circuit.
4 and a sample hold circuit 15. The differentiating circuit 14 differentiates the continuous measurement signal obtained from the converter 13 and detects the state of the signal that changes from time to time. Further, this differentiation circuit 14 is connected to the control section 12 and the sample hold circuit 15, and when the change in the differential value becomes zero, it supplies a degassing completion signal to the control section 12 and A hold signal of the output of the converter 13 is supplied to the sample port circuit 15. Further, the sample hold circuit 15 that receives this hold signal is configured to output the held value to the outside as a sample concentration value.
Next, the operation of the concentration measuring device configured as above will be explained.

First, this device uses a concentration meter detector 1 to detect air bubbles contained in the suspension.
The degassing device (1) removes the gas by degassing, but the degassing time is not set based on human intuition, but the device determines when defoaming is complete from the concentration measurement itself and holds that concentration measurement value. It is. That is, the concentration meter detector 11 with a degassing device shown in FIG. 2 starts degassing in response to a degassing start command from the control unit 12, detects concentration signals from time to time during the progress of degassing, and detects the subsequent concentration signal. The signal is sent to a differential path 14 through a signal converter 13. Therefore, the differentiating circuit 14 differentiates the signal supplied from the signal converter 13 and examines the state of change in the concentration signal. Generally, as degassing progresses, the suspension loses air bubbles, so the concentration signal shows a constant value. When the bubbles are completely eliminated, the concentration signal becomes constant, and when this is differentiated by the differentiating circuit 14, the change in the differential value becomes zero. At this time, it is determined that the defoaming has been completed, and the sample hold circuit 1 is transferred from the differentiating circuit 14 to the sample hold circuit 1.
A sample and hold command signal is given to signal converter 13.
Holds the output concentration measurement value. Further, the differentiating circuit 14 supplies a deaeration completion signal to the control section 12,
A command to finish degassing is issued to the concentration meter detector 11 with a degassing device. Thereafter, the control section 12 continues to control the control section 12.
That is, the control section 12 sends a sample release command signal to the detector 11 to cause the detector 11 to release the sample, and subsequently sends a sequential signal to the detector 11 to cause the detector 11 to perform sample filling. Therefore, as is clear from the above series of operations, the concentration measurement is performed by accurately knowing when the defoaming is completed, so that wasted time can be eliminated and the concentration measurement value can also be accurate. FIG. 3 shows another embodiment of the device of the present invention, in which a comparator circuit 17 is substituted for the differentiating circuit 14, which is a signal change detection circuit.
is provided to perform the same function.

That is, the comparator circuit 17 is configured to always compare the concentration value measured t seconds ago, and detects the completion of deaeration by detecting that there is no change between the value t seconds ago and the current concentration measurement value. It is something to do. Therefore, the comparator circuit 17 is
Naturally, there are two hold circuits, and these hold circuits are switched every t seconds to hold the output signal of the signal converter 13 and compare the two hold values. A circuit using this comparator circuit 17 also functions in exactly the same way as the differentiating circuit 14 in that it detects signal change values. Note that it is also possible to provide the comparator circuit 17 or the differentiator circuit 14 with the function of the control section 12. In this case, a series of commands are sent directly from both to the detector 11.
It will be sent to Further, the pipe 10 in which the detector 11 is installed may be a main flow path for the suspension, or may be a bypass pipe attached to the main pipe. As described in detail above, according to the device of the present invention, changes in the concentration signal of the concentration meter detector with a deaerator are detected by the subsequent electronic circuit, and when the signal change is zero, it is determined that defoaming has been completed, and the concentration is determined. Since the measured value is held, the concentration of the suspension can be accurately measured with just a simple electronic circuit.

This means that an appropriate degassing time can be selected, and the concentration can be measured accurately without relying on human uncertainty as in the past, and there is no wasted time and the complexity of measurement work is also eliminated. . Furthermore, since the electronic circuit of this device can be housed as is in a conventional electronic circuit case, the entire device can be simplified and its uses can be expanded without being subject to space constraints.

[Brief explanation of drawings]

Fig. 1 is a diagram illustrating a series of timings of the defoaming operation in a conventional device, Fig. 2 is a configuration diagram showing an embodiment of the concentration measuring device according to the present invention, and Fig. 3 is another example of the device of the present invention. FIG. DESCRIPTION OF SYMBOLS 10... Control part, 11... Concentration meter detector with deaerator, 13... Signal converter, 14... Differential circuit, 15...
...Sample hold fence, 17...Comparator circuit.

Claims (1)

[Scope of Claims] 1. In an apparatus for measuring the concentration of a suspension, a concentration meter detector with a deaerator that detects the concentration of the suspension while degassing air bubbles contained in the suspension; A signal change detection circuit detects a change in the concentration signal output from the concentration meter detector with a deaerator, and a detection signal of zero change in the concentration signal output from the signal change detection circuit detects the concentration signal. a sample hold circuit that holds the sample and outputs it as a measured value; and a control unit that receives a detection signal of zero change in the concentration signal from the signal change detection circuit and supplies a deaeration completion signal to the concentration meter detector with a deaeration device. What is claimed is: 1. A concentration measuring device characterized in that the completion of degassing can be determined from the concentration signal without setting a bubble degassing time. 2. The concentration measuring device according to claim 1, wherein the signal change detection circuit is constituted by a differentiating circuit or a comparator circuit.