JPH11326170A - Underwater odorant measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underwater odorant measuring device capable of stable zero and span calibration in a simple constitution. SOLUTION: An underwater odorant measuring device comprising a vaporizing part 7 continuously supplied with sample water and an odorless purge gas for separating odorants in the sample water from water and vaporizing them into the purge gas, a dehumidifying part 17 for removing moisture from the output gas of the vaporizing part 7 and stabilizing a dew point, and a sensor cell part 18 in which a gas sensor for measuring odorants is placed, characteristically comprises a means for supplying zero water and switching means 4 and 5 for switching between the sample water and the zero water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring trace amounts 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. Further, 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]

2. Description of the Related Art An odor sensor is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 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.

FIG. 4 is a configuration diagram of a conventional underwater odor substance measuring 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 for heating sample water and reference water (set temperature 45 ° C)
It is. SP1 and SP2 are each heated sample water. A sparger (bubbling device) for flowing clean air into the reference water to vaporize odor components.

[0004] WS1 is a water seal for preventing backflow of air from a spouter outlet. EX1, E
X2 is a dehumidifier for removing moisture from the output gas of SP1 and SP2, respectively. CL1 is a dehumidifier EX1,
This is a cooling water supply device that supplies cooling water having a constant temperature to EX2. SVs 4 and 5 are solenoid valves for switching a gas flow path. DET1 and DET2 are sensor cells each having an odor sensor element installed therein. C1 is a constant temperature chamber for keeping the temperature of the two sensor cells and the gas input to the cells at a constant temperature.

Reference numeral 101 denotes a sample water supply port. 102
Is a reference water supply port containing no odor component. 103 is a clean air supply port. 104 is a gas outlet. 10
Reference numeral 5 denotes a drain port for sample water and reference water.

[0006] The operation of the device thus constructed will be described below. 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 discharged from the drain port 105 via the water seal WS1. Similarly, the reference water is supplied to the sample water SP2 through the heating tank HE1 after the flow rate is adjusted by the flow meter FM2, and is supplied to the drain port 105 through the water seal WS1.
Is more exhausted.

Further, the clean air is divided into two flow paths, one of which is adjusted in flow rate by a flow meter FM3, and the sample water SP1 is
After the oil content of the sample water is vaporized
The water is removed at X1 and supplied to the solenoid valve SV4. Similarly, the other is adjusted in the 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.

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.
The sensor cell DET1 performs zero point calibration with the output gas from the reference water, and the sensor cell DET2
Measures the gas from the sample water.

Next, after a predetermined period of 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 When the output of the valve SV5 is supplied to the sensor cell DET2, the sensor cell D
In ET1, measurement of gas from the sample water is started, and in the sensor cell DET2, zero point calibration is performed using gas from the reference water. By repeating this, the sensor cell DE
One of T1 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]

However, according to the conventional apparatus, there are the following problems. For measurement and zero calibration, vaporizer (sparger),
Two systems of dehumidifiers are required, which is disadvantageous in cost, power consumption and size. If the characteristics of the two vaporizers and dehumidifiers, especially the dehumidifiers, have a slight variation, the humidity of the output gas will differ, and stable zero calibration cannot be performed. Stable calibration cannot be performed because it is difficult to stably dissolve the reference material in the sample water. The time constant of the entire system is large, and it is difficult to determine that odor has disappeared from the sample water.

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 measuring apparatus capable of performing stable zero and span calibration with a simple configuration.

[0012]

According to a first aspect of the present invention, a sample water and an odorless purge gas are continuously supplied to separate odorous substances in the sample water from the water to remove the odorous substances from the water. A vaporizing section 7 for vaporizing the
In the underwater odor substance measuring apparatus having a dehumidifying section 17 for removing moisture from the output gas of the vaporizing section and stabilizing the dew point and a sensor cell section 18 in which a gas sensor for measuring odor substances is installed. , Zero water supply means 2 and switching means 4 and 5 for switching between sample water and zero water.

According to the device configured as described above, since the sensor is always in a constant temperature and humidity, even a sensor having a relatively large temperature and humidity drift, such as a quartz oscillator type odor sensor, is stably used only for odor substances. Since the gas supplied to the sensor cell does not contain an odor component and the temperature and humidity have the same value as that at the time of the sample measurement, the zero point calibration can be performed without being affected by the temperature and humidity drift of the sensor. Further, since the switching means is provided, even if a drift occurs in the sensor output due to the measured odor substance, it is possible to determine a decrease in the odor substance in the sample water.

Here, the zero water is obtained by adding a reducing agent such as sodium ascorbate to pure water, purified water, river water containing no odorous substances, and purified water to neutralize chlorine. It is good to use water or odorless water. Here, the odorless water refers to water in which activated carbon is added to purified water, river water, or the like, or volatile organic substances are adsorbed through purified water, river water, or the like in an activated carbon tank.

The gas sensor may be a quartz oscillator type sensor. Further, as in claim 4, a differentiator 19 for calculating a differential output of the gas sensor output signal and a comparator 20 for comparing the differential output with a set value are provided, and immediately after switching the sample water to zero water. The differential output may be compared with a set value to determine that the odor in the sample water has disappeared. Here, the differentiator 19 may calculate the difference between the gas sensor outputs and other digital filter outputs.

According to a fifth aspect of the present invention, which achieves the above object, the sample water and the odorless purge gas are continuously supplied to separate the odorous substances in the sample water from the water and vaporize the purge gas. An underwater odor comprising a unit 7, a dehumidifying unit 17 for removing moisture from the output gas of the vaporizing unit and stabilizing the dew point, and a sensor cell unit 18 in which a gas sensor for measuring odorous substances is installed. In the substance measuring device, a cooling type dehumidifier is used as the dehumidifying unit, and a gas supply port is provided at any one of a gas phase portion of the vaporizing unit, a pipe between the vaporizing unit and the dehumidifying unit inlet, or the dehumidifying unit inlet. 13 is provided.

Here, it is preferable that the gas supply port has a zero gas supply means 8 connected to the gas supply port via a valve. Here, it is preferable that the same gas source as the purge gas supplied to the vaporizing section is used as the zero gas supply means. Also,
It is preferable that the gas supply port has a span calibration gas supply means 16 connected to the gas supply port via a valve.

Further, as in claim 9, stop means 6, 9 for stopping the supply of the sample water and the purge gas, a differentiator 19 for calculating a differential output of the gas sensor output, and a differential output Comparator 20 for comparing with set value
It is preferable that the sample water and the purge gas are stopped and the differential output immediately after the zero gas is supplied from the gas supply port is compared with a set value to determine that the odor in the sample water has disappeared.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below 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.

Reference numeral 11 denotes a gas output port of the sparger, 12 denotes a dehumidifier inlet, 14 denotes a valve, 17 denotes a cooling dehumidifier, and 18 denotes a sensor cell provided with a constant temperature means. ing. 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.

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 bottom of the sparger through the valve 9 through the air supply port 8, 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 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.

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 above the set dew point of the dehumidifier, the moisture is removed up to the dew point in the same way 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.

Also, when air having a dew point lower than the set dew point of the dehumidifier, such as dry air, is used as zero air, moisture removed from the sample during the measurement of the sample is removed from 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 values as those at the time of sample measurement.
Zero point calibration not affected by temperature and humidity drift of the sensor is possible.

After measuring the odor-containing sample water, the time constant for the odor of the sensor element and the
Due to such delays, the sensor output does not return to the zero point immediately. 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 using the differential signal has not always been effective.

In the method of determining the rise of the odorant concentration using the differential output of the sensor output, it is impossible to distinguish between the sensor drift and the odor output when the odor component concentration in the river water rises very slowly. In addition, there is a risk that the odor component concentration may be overlooked.

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 comparator 19 compares the output 19 of the differentiator with the set value 21 (for example, -0.5 Hz / min). 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. Also,
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.

FIG. 2 is a block diagram showing the configuration of a second embodiment of the present invention. In the figure, 4 and 5 are valves, 2 is a zero water tank having activated carbon inside, 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.

As the span calibration gas generator, a gas bag, a standard gas generator using a diffusion tube, or the like can be used. For example, when amyl acetate is used as a 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 microsyringe.

Next, the operation of the apparatus having the above-described structure will be described. During sample measurement, valves 4 and 14 are closed and 5, 9
Is set to open and measured as in Example 1.

At the time of zero point calibration, valve 5 is closed and valve 4 is closed.
Is opened, and zero water is supplied to the sparger instead of the sample water to perform zero point calibration.

By differentiating the sensor output before and after the zero point calibration, it is possible to determine a decrease in odor component concentration and to detect a very slow increase in odor component concentration, as in the first embodiment.

FIG. 3 shows that a very small amount of kerosene (3
3ppb) A signal diagram showing a measurement example of a sample dissolved in water, in which (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. Zero point calibration operation in the present invention,
This corresponds to the operation at time t2.

It can be seen that a differential output of about -1 Hz / min or less is output only immediately after the zero-point calibration for kerosene 33 ppb. For example, if the set value is set to -0.5 Hz / min, the sample water will be 33 ppb. It is possible to determine whether or not kerosene is contained.

During span calibration, valves 4, 5, and 9 are closed,
The pump 6 is stopped, the valve 14 is opened, and the span calibration gas is pumped by the pump 15 through the dehumidifier 17.
Lead to 8. 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.

In the above embodiment, the valve 1
4, 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, and may be attached only when performing span calibration, such as during maintenance. 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]

As described above, according to the first aspect of the present invention, the sample water and the odorless purge gas are continuously supplied, and the odorous substances in the sample water are separated from the water and vaporized in the purge gas. , A dehumidifying section 17 for removing moisture from the output gas of the vaporizing section and stabilizing the dew point, and a sensor cell section 18 in which a gas sensor for measuring odorous substances is installed. The underwater odor substance measuring device has a configuration including the zero water supply means 2 and the switching means 4 and 5 for switching between the sample water and the zero water. Even if a drift occurs in the output, it is possible to determine a decrease in odorous substances in the sample water.

Thus, for example, when used for water quality control of tap water at a water purification plant, it is possible to determine when water intake can be resumed when water intake is stopped due to an increase in odor intensity. 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.

Further, according to the first embodiment, a very simple configuration in which one valve 14 is added in addition to the valve 9 is provided.
Zero point calibration not affected by temperature and humidity drift of the sensor element can be performed.

Further, according to the second embodiment, with simple calibration,
It is possible to calibrate the zero point and the span which are not affected by the temperature / humidity drift of the sensor element.

[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 odor substance 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 (9)

[Claims] 1. A vaporizer (7) for continuously supplying sample water and an odorless purge gas to separate odorous substances in the sample water from water and vaporize the purge gas, and an output gas from the vaporizer. A dehumidifying unit (17) for removing moisture and stabilizing the dew point, and a sensor cell unit (18) in which a gas sensor for measuring odorous substances is installed.
An apparatus for measuring an odorous substance in water, comprising: means for supplying zero water (2); and switching means (4, 5) for switching between sample water and zero water. 2. 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. The underwater odor substance measurement device according to claim 1, wherein: 3. The underwater odor substance measuring device according to claim 1, wherein the gas sensor is a quartz oscillator type sensor. And a comparator (20) for calculating a differential output of the gas sensor output signal and a comparator (20) for comparing the differential output with a set value. 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 the differential output with a set value. 5. A vaporizer (7) for continuously supplying sample water and an odorless purge gas to separate odorous substances in the sample water from the water and vaporize the purge gas, and water from the output gas of the vaporizer. A dehumidifying section (17) for removing water and stabilizing a dew point, and a sensor cell section (18) in which a gas sensor for measuring an odorous substance is installed. And a gas supply port (13) at any one of a gas phase portion of the vaporization section, a pipe between the vaporization section and the dehumidification section inlet, or the dehumidification section entrance. Underwater odor substance measurement device. 6. The underwater odor substance measuring device according to claim 5, further comprising zero gas supply means connected to the gas supply port via a valve. 7. The underwater odor substance measuring apparatus according to claim 6, wherein the zero gas supply means uses the same gas source as the purge gas supplied to the vaporizing section. 8. The underwater odor substance measuring apparatus according to claim 5, further comprising a span calibration gas supply means connected to the gas supply port via a valve. 9. A stopping means (6, 9) for stopping the supply of the sample water and the purge gas; a differentiator (19) for calculating a differential output of the gas sensor output;
A comparator (20) for comparing the differential output with a set value,
The method according to claim 5, wherein the odor in the sample water is eliminated by comparing the differential output immediately after supplying the zero gas from the gas supply port with the sample water and the purge gas to a set value. Underwater odor substance measurement device.