JP3554761B2 - Underwater odor substance measurement device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for measuring a trace amount of odorous substances, particularly oil, mixed in water such as raw tap water, and more particularly to an apparatus capable of performing stable zero and span calibration with a simple configuration. Also, the present invention relates to a method for determining the termination of an oil accident (mixing of oil into river water or the like), which was difficult to determine conventionally.
[0002]
[Prior art]
An odor sensor is disclosed in, for example, Japanese Patent Application Laid-Open No. 5-296907 proposed by the present applicant. Such an odor sensor has a structure in which an odor sensitive film is stuck on a quartz oscillator. When an abnormal substance such as a volatile oil component is adsorbed on the odor sensitive film, the resonance frequency of the quartz oscillator shifts, and the shift amount is used as the sensor output.
[0003]
FIG. 4 is a configuration diagram of a conventional underwater odorant measurement device. In the figure, FM1 to FM4 are flow meters each having a needle valve for adjusting a flow rate. HE1 is a heating tank (set temperature 45 ° C.) for heating the sample water and the reference water. SP1 and SP2 are each heated sample water. A sparger (bubbling device) for flowing clean air into reference water to vaporize odor components.
[0004]
WS1 is a water seal for preventing backflow of air from the spouter outlet. EX1 and EX2 are dehumidifiers for removing water from the output gas of SP1 and SP2, respectively. CL1 is a cooling water supply device that supplies cooling water having a constant temperature to the dehumidifiers EX1 and EX2. SVs 4 and 5 are solenoid valves for switching the gas flow path. DET1 and DET2 are sensor cells each having an odor sensor element installed therein. C1 is a constant temperature bath for keeping the temperature of the two sensor cells and the gas input to the cells at a constant temperature.
[0005]
101 is a sample water supply port. Reference numeral 102 denotes a reference water supply port containing no odor component. 103 is a clean air supply port. 104 is a gas outlet. Reference numeral 105 denotes a drain port for sample water and reference water.
[0006]
The operation of the device configured as described above will now be described. After the flow rate of the sample water is adjusted by the flow meter FM1, the sample water is supplied to the sample water SP1 through the heating tank HE1, and is discharged from the drain port 105 via the water seal WS1. Similarly, after the flow rate of the reference water is adjusted by the flow meter FM2, the reference water is supplied to the sample water SP2 through the heating tank HE1, and is discharged from the drain port 105 via the water seal WS1.
[0007]
Further, the clean air is divided into two flow paths, one of which is supplied to the sample water SP1 with the flow rate adjusted by a flow meter FM3, and after the oil content of the sample water is vaporized, the moisture is removed by a dehumidifier EX1. It is supplied to SV4. Similarly, the other is adjusted in flow rate by the flow meter FM4 and supplied to the sample water SP2. After the oil content of the sample water is vaporized, the moisture is removed by the dehumidifier EX2 and supplied to the solenoid valve SV5.
[0008]
First, the output of the solenoid valve SV4 is supplied to the sensor cell DET2, and the output of the solenoid valve SV5 is supplied to the sensor cell DET1. In the sensor cell DET1, the zero point calibration is performed using the output gas from the reference water. Gas is being measured.
[0009]
Next, after a preset fixed time (after the output of the sensor cell DET1 is stabilized and the zero-point calibration is completed), the solenoid valves SV4 and SV5 are switched, and the output of the solenoid valve SV4 is changed to the sensor cells DET1 and SV5. When the output is supplied to the sensor cell DET2, measurement of gas from the sample water is started in the sensor cell DET1, and zero point calibration is performed in the sensor cell DET2 using gas from the reference water. By this repetition, one of the sensor cells DET1 and DET2 is always in the state of measuring the sample water and the other is always in the state of performing the zero point calibration, and the continuous measurement is performed.
[0010]
[Problems to be solved by the invention]
However, the conventional apparatus has the following problems (1) to (4).
(1) Two systems of vaporizer (sparger) and dehumidifier are required for measurement and zero calibration, which are disadvantageous in cost, power consumption and size.
{Circle around (2)} If the characteristics of the two vaporization units and dehumidification units, especially the characteristics of the dehumidification units, vary even slightly, the humidity of the output gas will differ, and stable zero calibration cannot be performed.
(3) Stable span calibration cannot be performed because it is difficult to stably dissolve the standard substance in the sample water.
(4) The time constant of the entire system is large, and it is difficult to determine that odor has disappeared from the sample water.
[0011]
An object of the present invention is to solve such a problem, and an object of the present invention is to provide an underwater odor substance measurement device capable of performing stable zero and span calibration with a simple configuration.
[0012]
[Means for Solving the Problems]
In order to achieve such an object, the present invention described in claim 1 provides:
An underwater odor substance measurement having a vaporizing section that supplies an odorless purge gas to the sample water, separates odor substances in the sample water and vaporizes the odor substance into the purge gas side, and a gas sensor that measures the odor substance of the gas output from the vaporizing section. In the apparatus, a dehumidifier that removes the moisture of the gas output from the vaporizer to a predetermined dew point, a gas phase portion of the vaporizer, a pipe between the vaporizer and the dehumidifier, or an inlet of the dehumidifier. It is characterized by having a gas supply port provided in any one of them, and a zero gas supply means for supplying a zero gas to the gas supply port.
[0013]
Further, as in claim 2, an odorless purge gas is supplied to the sample water to separate an odorous substance in the sample water and vaporize it to the purge gas side, and the odorous substance of the gas output from the vaporization section is measured. A dehumidifier that removes the moisture of the gas output from the vaporizing unit to a predetermined dew point, and a gas phase portion of the vaporizing unit, between the vaporizing unit and the dehumidifying device. , Or a gas supply port provided at one of the inlets of the dehumidifier, and a span calibration gas supply means for supplying a span calibration gas to the gas supply port.
[0014]
Further, as in claim 3, an odorless purge gas is supplied to the sample water to separate odorous substances in the sample water and vaporize them to the purge gas side, and the odorous substance of the gas output from the vaporizing section is measured. An underwater odorant measuring device having a gas sensor that performs switching between the sample water and the zero water and supplies zero water to the vaporizing unit, and removes moisture of the gas output from the vaporizing unit to a predetermined dew point. A dehumidifier, a gas phase portion of the vaporization unit, a pipe between the vaporization unit and the dehumidifier, or a gas supply port provided at any of the dehumidifier inlets, and a span calibration gas supplied to the gas supply port. A span calibration gas supply means for supplying;
It is characterized by having.
[0015]
As described in claim 4, the zero water is pure water, purified water, river water containing no odorous substances, water obtained by adding a reducing agent such as sodium ascorbate to purified water to neutralize chlorine, or odorless water. It is characterized by being.
[0016]
According to a fifth aspect of the present invention, the gas sensor is a quartz oscillator type sensor.
[0017]
According to a sixth aspect of the present invention, there is provided a differentiator for calculating a differential output of the gas sensor output, and a comparator for comparing the differential output with a set value. The sample water and the purge gas are stopped, and zero gas is supplied from the gas supply port. By comparing the differential output immediately after the supply with the set value, it is determined that the odor in the sample water has disappeared.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, 1 is a sample water supply port, 6 is a sample water pump, 8 is an air supply port used as purge gas and zero gas, 7 is a vaporizer (sparger) for flowing air into the sample water to vaporize odor components, 9 is a valve, 10 is a sparger sample water discharge port, and 13 is a zero gas supply port, which is provided in the gas phase portion of the sparger 7.
[0020]
11 is a gas output port of the sparger, 12 is a dehumidifier inlet, 14 is a valve, 17 is a cooling type dehumidifier, and 18 is a sensor cell provided with a constant temperature means, and a quartz oscillator type smell sensor is installed therein. 19 is a differentiator for differentiating the sensor output, 20 is a comparator for comparing the differentiator output with a set value 21, and 22 is a comparator output.
[0021]
During the measurement, the valve 9 is open and the valve 14 is closed. Sample water is supplied from a supply port 1 to a sparger 7 by a sample water pump 6 and discharged from a discharge port 10. On the other hand, zero air is supplied from the air supply port 8 through the valve 9 from the bottom of the sparger, and odorous substances in the water are vaporized into the air. The air containing the odorous substance enters the cooling type dehumidifier 17 from the air outlet 11, and only the moisture is removed up to a predetermined dew point (set temperature of the dehumidifier). And is applied to the sensor. At this time, since the sensor is always in a constant temperature and humidity, even a sensor having a slightly large temperature and humidity drift, such as a quartz oscillator type odor sensor, can stably measure only the odor substance.
[0022]
At the time of zero calibration, the pump 6 is stopped, the valve 9 is closed, and the valve 14 is opened. Then, the zero air is directly supplied to the dehumidifier 17 without touching the sample water possibly containing the odor. If the zero air contains moisture equal to or higher than the dew point set for the dehumidifier, the moisture is removed to the dew point in the same manner as the sparger output gas. The fact that the dew point of the output gas is stable even if the dew point of the input gas is slightly different is a feature of the cooling type dehumidifier.
[0023]
Also, when air with a dew point lower than the set dew point of the dehumidifier, such as dry air, is used as zero air, water removed from the sample during sample measurement will cause water droplets to form on the inner wall of the flow path of the cooled dehumidifier. The dew point of the output gas of the dehumidifier becomes equal to the set dew point of the dehumidifier for a while (for example, about one hour). (In this case, the cooling dehumidifier functions as a humidifier.) Therefore, the gas supplied to the sensor cell does not contain an odor component, and the temperature and humidity have the same value as that of the sample measurement. Zero point calibration not affected by drift is possible.
[0024]
After the measurement of the odor-containing sample water, the sensor output does not immediately return to the zero point due to the time constant for the odor of the sensor element and the delay of the sparger 7 or the like. In addition, depending on the odor component, once it adheres to the sensor element, it accumulates without being desorbed and causes a drift in the sensor output. In such a case, the rise of the gas sensor output can be determined by the differential signal. However, the method of determining the fall of the gas sensor output by the differential signal has not always been effective.
[0025]
In the method of determining the rise of the odorant concentration using the differential output of the sensor output, the sensor drift and the odor output cannot be distinguished when the odor component concentration in the river water increases very slowly. There was a risk of overlooking the rise in concentration.
[0026]
In this case, when it is determined that the odor component in the sample water has disappeared, a zero-point calibration operation is performed from the above-described sample measurement operation. The output 19 is compared with the set value 21 (for example, -0.5 Hz / min) by the comparator 20. If the output 19 is larger than that (if the absolute value is smaller), it can be determined that the odorant in the sample water has disappeared. If it is smaller than the set value, it can be determined that the sample water contains an odor component having a concentration equal to or higher than the specified value.
[0027]
FIG. 2 is a configuration block diagram showing a second embodiment of the present invention. In the figure, 4 and 5 are valves, 2 is a zero water tank having activated carbon therein, 6 is a water pump, 15 is a span calibration gas supply pump, 16 is a span calibration gas generator, and 23 is a span calibration gas supply port. .
[0028]
As a span calibration gas generator, a standard gas generator using a gas bag, a diffusion tube, or the like can be used. For example, when amyl acetate is used as the span calibration gas, a standard gas having a concentration of several hundred ppm can be produced by filling a gas bag having a capacity of several L with zero air and injecting and evaporating several μL of amyl acetate with a micro syringe.
[0029]
The operation of the device configured as described above will now be described. At the time of sample measurement, the valves 4 and 14 are set to be closed, and the valves 5 and 9 are set to be open.
[0030]
At the time of zero point calibration, the valve 5 is closed and the valve 4 is opened, and zero water is supplied to the sparger instead of the sample water to perform zero point calibration.
[0031]
By differentiating the sensor output before and after the zero point calibration, it is possible to determine a decrease in the odor component concentration and detect a very slow increase in the odor component concentration, as in the first embodiment.
[0032]
FIG. 3 is a signal diagram showing a measurement example of a sample in which kerosene is dissolved in a trace amount (33 ppb) of water as an odor component, wherein (A) shows a frequency change and (B) shows a differential value. In the figure, zero water is supplied from time t0, water containing a trace amount of kerosene is supplied at time t1, and zero water is supplied again at time t2. The zero point calibration operation in the present invention corresponds to the operation at time t2.
[0033]
It can be seen that a differential output of about -1 Hz / min or less is output only for the zero point calibration for kerosene 33 ppb. For example, if the set value is set to -0.5 Hz / min, 33 ppb of kerosene will be contained in the sample water. It is possible to determine whether or not it is included.
[0034]
During span calibration, the valves 4, 5, and 9 are closed, the pump 6 is stopped, the valve 14 is opened, and the span calibration gas is guided by the pump 15 to the sensor cell 18 through the dehumidifier 17. At this time, since water droplets adhere to the flow path inner wall of the cooling dehumidifier 17, the span gas having a dew point equal to the dew point set for the dehumidifier regardless of whether the dew point of the span calibration gas is higher or lower than the set value of the dehumidifier. Is supplied to the sensor cell, and the temperature and humidity in the sensor cell are always kept constant. Therefore, span calibration can be performed without being affected by the temperature and humidity drift of the sensor.
[0035]
In the above embodiment, the valve 14, the pump 15, and the span calibration gas 16 have been described as being installed inside the apparatus. However, the present invention is not limited to this. It may be attached only to. In this case, only the span calibration gas (zero-point calibration gas) supply port 23 is installed in the apparatus. Further, instead of the differentiator 19, a differentiator or a digital filter having substantially the same function as this may be used.
[0036]
【The invention's effect】
As described above, the present invention,
An underwater odor substance measurement having a vaporizing section that supplies an odorless purge gas to the sample water, separates odor substances in the sample water and vaporizes the odor substance into the purge gas side, and a gas sensor that measures the odor substance of the gas output from the vaporizing section. In the apparatus, a dehumidifier that removes the moisture of the gas output from the vaporizing unit to a predetermined dew point, a gas phase part of the vaporizing unit, a pipe between the vaporizing unit and the dehumidifier, or an inlet of the dehumidifier. A gas supply port provided in any one of them provides a simple configuration and stable zero and span calibration for measurement of oil content and the like.
Also provided is a differentiator for calculating the differential output of the gas sensor output, and a comparator for comparing the differential output with a set value. The differential output immediately after the sample water and purge gas are stopped and zero gas is supplied from the gas supply port is provided. Is compared with the set value, it can be determined that the odor in the sample water has disappeared, and the sensor drift can be distinguished.
[0037]
Thus, for example, when used for water quality management of tap water at a water purification plant, when odor intensity increases and water intake is stopped, it is possible to determine when water intake can be resumed. In addition, it is possible to detect a gradual increase in the concentration of the odor component, which cannot be detected only by determining the rise.
[0038]
Further, according to the first embodiment, it is possible to perform zero point calibration that is not affected by the temperature / humidity drift of the sensor element with a very simple configuration in which one valve 14 is added in addition to the valve 9.
[0039]
Further, according to the second embodiment, the zero point and the span which are not affected by the temperature / humidity drift of the sensor element can be calibrated by simple calibration.
[Brief description of the drawings]
FIG. 1 is a configuration block diagram showing one embodiment of the present invention.
FIG. 2 is a configuration block diagram showing a second embodiment of the present invention.
FIG. 3 is a measurement example of a sample in which kerosene is dissolved in a trace amount of water as an odor component.
FIG. 4 is a configuration diagram of a conventional underwater odorant measurement device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sample water supply port 2 Zero water tank 3 Air supply port 7 Vaporizer 17 Dehumidifier 18 Sensor cell

Claims (6)

An underwater odor substance measurement having a vaporizing section that supplies an odorless purge gas to the sample water, separates odor substances in the sample water and vaporizes the odor substance into the purge gas side, and a gas sensor that measures the odor substance of the gas output from the vaporizing section. In the device,
A dehumidifier that removes the moisture of the gas output from the vaporizing unit to a predetermined dew point,
A gas supply port provided at any one of a gas phase portion of the vaporization unit, a pipe between the vaporization unit and the dehumidifier, or an inlet of the dehumidifier;
Zero gas supply means for supplying zero gas to the gas supply port,
An underwater odor substance measuring device, characterized by having: An underwater odor substance measurement having a vaporizing section that supplies an odorless purge gas to the sample water, separates odor substances in the sample water and vaporizes the odor substance into the purge gas side, and a gas sensor that measures the odor substance of the gas output from the vaporizing section. In the device,
A dehumidifier that removes the moisture of the gas output from the vaporizing unit to a predetermined dew point,
A gas supply port provided at any one of a gas phase portion of the vaporization unit, a pipe between the vaporization unit and the dehumidifier, or an inlet of the dehumidifier;
Span calibration gas supply means for supplying a span calibration gas to the gas supply port,
An underwater odor substance measuring device, characterized by having: An underwater odor substance measurement having a vaporizing section that supplies an odorless purge gas to the sample water, separates odor substances in the sample water and vaporizes the odor substance into the purge gas side, and a gas sensor that measures the odor substance of the gas output from the vaporizing section. In the device,
Zero water supply means for switching the sample water and zero water and supplying the water to the vaporization unit,
A dehumidifier that removes the moisture of the gas output from the vaporizing unit to a predetermined dew point,
A gas supply port provided at any one of a gas phase portion of the vaporization unit, a pipe between the vaporization unit and the dehumidifier, or an inlet of the dehumidifier;
Span calibration gas supply means for supplying a span calibration gas to the gas supply port,
An underwater odor substance measuring device, characterized by having: The zero water is pure water, purified water, river water not containing odorous substances, water obtained by adding a reducing agent such as sodium ascorbate to purified water to neutralize chlorine, or odorless water. The underwater odor substance measuring device according to claim 3 . The underwater odor substance measuring device according to any one of claims 1 to 4 , wherein the gas sensor is a quartz oscillator sensor. A differentiator for calculating the differential output of the gas sensor output, and a comparator for comparing the differential output with a set value, stopping the sample water and the purge gas and stopping the differential output immediately after supplying zero gas from the gas supply port. 2. The underwater odor substance measurement device according to claim 1 , wherein it is determined that the odor in the sample water has disappeared by comparing with the set value.

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