JPH0531547Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> The present invention is a gas analysis system in which sample gas from a sample gas discharge source is supplied to an analysis section through an analysis line, and calibration gas is also supplied to the analysis section. Regarding equipment.

<Conventional technology> Conventional gas analyzers generally introduce sample gas into the analysis section using a diaphragm pump (a reciprocating pump with a built-in diaphragm) driven by a motor. There are two types of systems: one is a system in which a diaphragm pump is placed upstream of the analysis part to pump the sample gas to the analysis part, and the other is a system in which a diaphragm pump is placed downstream of the analysis part and the sample gas is sucked into the analysis part.

This pressure-feed type gas analyzer is shown in FIG. 3, and the suction type gas analyzer is shown in FIG. 4, and will be described.

In FIGS. 3 and 4, reference numeral 1 is a dehumidifying cooler for sample gas, reference numeral 2 is a diaphragm pump, reference numeral 3 is a solenoid valve unit for supplying calibration gas,
Reference numeral 4 is an analysis section that analyzes sample gas; reference numeral 5
numeral 6 indicates a flow meter, and numeral 6 indicates a buffer tank.

In the case of the pressure feeding method, a dehumidifying cooler 1, a diaphragm pump 2, a solenoid valve unit 3, an analysis section 4, and a flow meter 5 are arranged in this order from upstream of the analysis line.
In the case of the suction method, the dehumidifying cooler 1, solenoid valve unit 3, analysis section 4, flow meter 5,
A buffer tank 6 and a diaphragm pump 2 are arranged in this order. In the case of the suction method, pulsations occur in the amount of sample gas sucked, so it is necessary to provide a buffer tank 6 upstream of the diaphragm pump 2 to suppress the pulsations.

Regarding pressure-feeding gas analyzers,
There are systems that use a single diaphragm pump 2 to pump sample gas to multiple analysis lines and analyze multiple components in parallel, such as with automobile exhaust gas. Regarding the apparatus, a single analysis line equipped with a diaphragm pump 2 was used to analyze a single component.

<Problems to be solved by the invention> However, in the case of the conventional example having such a configuration, there are the following problems.

That is, since the diaphragm pump 2 itself has drawbacks such as being relatively large, heavy, power consuming, vibrating, pulsating, and expensive, special consideration must be given to its installation space and arrangement condition. However, the overall size of the device becomes larger and the structure becomes more complicated. Furthermore, the structure of piping around the diaphragm pump 2, dehumidifying cooler 1, etc. is restricted.

Therefore, the inventors of the present invention proposed an ejector pump as an alternative to the diaphragm pump 2, which is superior to the diaphragm pump 2 in all aspects such as smaller size, lower weight, lower power consumption, lower vibration, no pulsation, and lower cost. We focused on this and thought of using this ejector pump to suck and introduce the sample gas into the analysis line.

However, ejector pumps generally have a problem in that pressure fluctuations in the driving air and the suctioned gas have a large effect on the amount of sample gas suctioned.
If such an ejector pump is installed in the analysis line as it is, the following problems will occur.

In other words, the high-pressure air used in normal factory production lines is used as the driving air.
Fluctuations in the pressure of the driving air directly result in variations in the amount of sample gas sucked. Furthermore, since the ejector pump can only be used as a suction system, if the discharge pressure of the sample gas from the sample gas discharge source fluctuates, the amount of sample gas suctioned into the analysis section 4 will vary. If the amount of sample gas sucked varies in this way, the error in the indication of the analysis section 4 increases, making it impossible to perform accurate measurements.

Furthermore, during calibration, the calibration gas is pressurized using a cylinder or the like and supplied to the analysis line in a depressurized state, so the amount of calibration gas suctioned by the ejector pump differs from the amount of sample gas suctioned, and the analysis section 4 is Correct calibration will not be possible.

Because of these inconveniences, it is problematic to simply replace the ejector pump with the diaphragm pump 2 in the gas analyzer.

The present invention was devised in view of the above circumstances, and aims to provide a gas analyzer that can have a compact and simple structure as a whole and can perform accurate measurements.

<Means for Solving the Problems> In order to achieve this purpose, the present invention employs an ejector pump that can eliminate the drawbacks of diaphragm pumps, thereby eliminating the above-mentioned inconveniences that occur when using ejector pumps. It was structured like this.

That is, the gas analyzer according to the present invention is configured to supply a sample gas from a sample gas discharge source to an analysis section through an analysis line, and also to supply a calibration gas to the analysis section, wherein: an ejector pump that is disposed downstream of the installation position of the analysis section and sucks the sample gas; a driving air pressure adjustment means that adjusts the pressure of the air for driving the ejector pump to a constant level; sample gas pressure adjustment means for adjusting the variation in discharge pressure of the sample gas to a constant level; differential pressure adjustment means for adjusting the differential pressure between the inlet and outlet of the analysis section to a constant level; The present invention is characterized in that it includes a calibration gas pressure correction means for correcting the pressure by reducing the pressure so as to correspond to the pressure of the sample gas.

<Effect> The effects of the configuration of the present invention are as follows.

Since an ejector pump is used, which is smaller, lighter in weight, consumes less power, has less vibration, does not pulsate, and is cheaper than a diaphragm pump, the motor that is required with a diaphragm pump is not required, making the entire device compact and simple in structure. become.

Even if driving air whose pressure fluctuates is used, the pressure is adjusted to a constant level by the driving air pressure adjusting means, so there is no variation in the amount of sample gas sucked by the ejector pump. Moreover, even if the discharge pressure of the sample gas from the sample gas discharge source fluctuates, it is adjusted to a constant level by the sample gas pressure adjusting means, so that the sample gas at a constant pressure flows into the analysis section. Furthermore, since the differential pressure between the inlet and outlet of the analysis section is adjusted to a constant value by the differential pressure adjusting means, the sample gas flow rate within the analysis section is maintained constant.

Moreover, during calibration, the pressure of the calibration gas supplied in a pressurized state is corrected by the calibration gas pressure correction means to reduce the pressure in accordance with the adjusted pressure of the sample gas, so that the amount of calibration gas sucked into the analysis section is reduced. is almost the same as the sample gas suction amount.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a functional block diagram of the gas analyzer of the present invention. In this figure, the same reference numerals as those given in FIG. 4 according to the conventional example refer to the same parts or corresponding parts.

The configurations of this embodiment that differ from the conventional example shown in FIG. 4 are as follows.

An ejector pump 7 is provided in place of the diaphragm pump 2. This ejector pump 7 is configured to generate negative pressure using driving air and suck the sample gas.

When installing the ejector pump 7, a driving air pressure adjusting means 8 is provided on the driving air supply side of the ejector pump 7, a differential pressure adjusting means 9 is provided in parallel to the analysis section 4, and a dehumidifying cooler 1 is provided. A sample gas pressure adjustment means 10 is provided in parallel to the sample gas pressure, and further,
A calibration gas pressure correction means 11 is provided in the calibration gas line.

The driving air pressure adjusting means 8 adjusts the pressure of the driving air to a constant level even if the pressure of the driving air fluctuates.
This is for constantly introducing driving air at a constant pressure into the ejector pump 7, thereby stabilizing the amount of sample gas sucked by the ejector pump 7.

The differential pressure adjustment means 9 is for adjusting the differential pressure of the sample gas at the entrance and exit of the analysis section 4 to a constant value, and thereby maintains the sample gas flow rate inside the analysis section 4 at a constant level. .

The sample gas pressure adjustment means 10 is for adjusting the pressure of the sample gas to a constant level when the discharge pressure of the sample gas from the sample gas discharge source fluctuates, and the sample gas pressure adjustment means 10 adjusts the pressure of the sample gas to a constant value when the discharge pressure of the sample gas from the sample gas discharge source fluctuates.
This is to prevent indication errors from occurring.

The calibration gas pressure correction means 11 corrects the pressure of the calibration gas supplied from a cylinder or the like in a pressurized state by reducing the pressure in accordance with the adjusted pressure of the sample gas.
This is to make the amount of calibration gas suctioned into the analysis section 4 substantially the same as the amount of sample gas suctioned.

FIG. 2 is a configuration diagram of a gas analyzer according to an embodiment of the present invention. The gas analyzer here is configured to separately analyze each component of automobile exhaust gas. In this figure, the same reference numerals as those in FIG. 1 refer to the same parts or corresponding parts.

That is, a cooler 1a as a dehumidifying cooler 1 and a filter 1b are provided near the conduit G attached to the exhaust pipe of an automobile, and the dehumidifying cooler 1 lowers the dew point of the sample gas and Drain and dust contained in the gas are collected in a drain pot 12 and discharged to the outside from a solenoid valve 13 as necessary.

A pressure sensor 14 is provided between the cooler 1a and the filter 1b, and an output signal from the pressure sensor 14 controls a solenoid valve 10a as a sample gas pressure adjustment means 10 provided upstream of the cooler 1a. The pressure of the sample gas is adjusted to a constant value. This pressure-adjusted sample gas is introduced into the analysis line.

A flow control block 15 is provided downstream of the filter 1b via a solenoid valve _V1 . The flow control block 15 is comprised of a solenoid valve unit 3 for supplying calibration gas consisting of zero gas and span gas to various analyzers to be described later, and pressure regulators 11a to 11d as calibration gas pressure correction means 11. The solenoid valve unit 3 is composed of zero gas solenoid valves 3a to 3d and span gas solenoid valves 3e to 3h. Symbols V ₂ to _{V 5} are electromagnetic valves for switching between the measurement state and the calibration state. That is, the pressure of the calibration gas is adjusted to a constant level by the pressure regulators 11a to 11d, and the calibration gas flows to various analyzers to be described later.

Downstream of this flow control block 15 are a known infrared analyzer 16, a chemiluminescent analyzer 17, and a flame ionization analyzer 1, respectively.
8 is provided. Infrared analyzer 16 (abbreviation)
NDIR) of exhaust gas as sample gas
The chemiluminescence analyzer 17 (abbreviated as CLD) detects CO components and CO ₂ components, and the chemiluminescence analyzer 17 (abbreviated as CLD)
The flame ionization analyzer 18 (abbreviated as FID) detects NO components or NO _x components, and the flame ionization analyzer 18 (abbreviated as FID) detects total HC components.

The infrared analyzer 16 includes analysis sections 4a and 4b,
differential pressure regulator 9a as differential pressure adjustment means 9;
9b, flow meters 16a, 16b, and relief valve 1
6c, 16d, and a plurality of capillaries 16e.

The chemiluminescent analyzer 17 includes an analysis section 4c, a differential pressure regulator 9c as a differential pressure adjusting means 9,
NO _x converter 17a, O ₃ generator 17b,
It includes an O ₃ decomposer 17c, a flow meter 17d, a relief valve 17e, and a plurality of capillaries 17f.

The hydrogen flame ionization analyzer 18 has an analysis section 4d.
and a differential pressure regulator 9 as differential pressure adjusting means 9.
d, a flow meter 18a, a relief valve 18b, and a plurality of capillaries 18c.

Each of the flowmeters 16a, 16b, 17d, 18a
is a pressure regulator 11a that detects abnormalities and is provided in the flow control block 15.
~11d, when the pressure of the calibration gas cannot be fully adjusted, the excess calibration gas overflows, and each relief valve 16c, 16d, 17e,
Reference numeral 18b is used to suck in external air when an abnormality occurs during calibration and calibration gas is not supplied.

Ejector pumps 7a and 7b are provided downstream of each of these analyzers 16 to 18 via pressure reducing regulators 19a and 19b. The ejector pump 7c includes a flowmeter 5 downstream of the solenoid valve _V1 .
It is provided via a solenoid valve 20 and two needle valves 21a and 21b. Note that the solenoid valve 20 maintains a balance between the measurement state and the calibration state when they coexist (when calibrating only a single component during measurement), and the needle valves 21a and 21b maintain the balance between the measurement state and the calibration state when they coexist. This is to adjust the flow rate between the two.

The drive air supply ports of the ejector pumps 7a to 7c are connected to, for example, a factory airline (or drive air supply source) via a single pressure regulator 8a as a drive air pressure adjustment means 8 and a dehumidifier 8b.
It is connected to the.

Next, the operation will be explained. Here, the flow path of the infrared analyzer 16 will be mainly described.

During measurement, exhaust gas from the automobile is sucked into the conduit G by driving the ejector pump 7a, drain and dust are removed via the cooler 1a and the filter 1b, and the solenoid valve V ₁ of the flow control block 15 is removed. Open ~ _V3 to introduce the cleaned sample gas into the analysis line. In addition,
The driving air that supplies the ejector pump 7a is high-pressure air from a production line in a factory with pressure fluctuations and insufficient dehumidification.The dew point of this high-pressure air is first lowered in a dehumidifier 8b, and then the pressure regulator 8a is used. is controlled to a constant pressure.

The flow rate and pressure conditions of the sample gas are determined by a preset pressure and each capillary.
Even if the discharge pressure of exhaust gas from the automobile increases, the pressure at point B is detected by the pressure sensor 14, and based on this, the solenoid valve 10a is controlled to ensure that the pressure at point A exceeds a predetermined value. Since the pressure at point B is prevented from occurring, the pressure at point B is stabilized within a predetermined range.

The pressures at points C and E are controlled to be constant by differential pressure regulators 9a and 9b as differential pressure adjusting means 9, and the pressure at point D is controlled to be constant by pressure reducing regulator 19a, so the pressure at point C is controlled to be constant by pressure reducing regulator 19a. and point D
The pressure difference between the points E and D and between points E and D is configured to be constant. In other words, point C and point D
Since the differential pressure between the two points E and D is always adjusted to be constant, the amount of sample gas sucked into the analysis sections 4a and 4b is kept constant.

By the way, when calibrating the analysis units 4a and 4b, the solenoid valves _V1 to _V3 are closed and zero gas is supplied to the solenoid valve 3.
a, 3b and pressure regulators 11a, 11b
It is introduced into the analysis section 4 via. At this time, point C,
The pressure at point E is about to become higher than at the time of measurement, but
The pressure is adjusted to a constant level by differential pressure regulators 9a and 9b. When the differential pressure regulators 9a and 9b cannot fully adjust, the flowmeters 16a and 16b adjust accordingly.
and is bypassed to the outside via the capillary 16e. In the case of span gas, the pressure is adjusted to a constant value in substantially the same manner as described above so as to prevent indication errors in the analysis sections 4a and 4b.

As for the other chemiluminescence analyzer 17 and the flame ionization analyzer 18, the indication errors of the analyzers 4c and 4d are stably controlled in the same way as the infrared analyzer 16.

In the measurement state, if it is necessary to calibrate only a specific single component, the pressure change at point B is prevented by opening the solenoid valve 20 and increasing the bypass flow rate flowing through the flow meter 5. do. The bypass flow rate can be adjusted by needle valves 21a and 21b.

As is clear from the above explanation, the inconveniences that may occur when using the ejector pump 7 (described in the section of problems with the prior art) have been addressed by the drive air pressure adjustment means 8 and the differential pressure adjustment means 9. , can be solved by the sample gas pressure adjustment means 10 and the calibration gas pressure correction means 11. That is, since driving air adjusted to a constant pressure by the driving air pressure adjusting means 8 is supplied to the ejector pump 7, variations in the amount of sample gas sucked can be prevented. Further, since the pressure of the sample gas flowing into the analysis line is adjusted to a constant value by the sample gas pressure adjustment means 10, the sample gas at a constant pressure can always be introduced into the analysis section 4. Furthermore, since the differential pressure adjusting means 9 maintains the differential pressure between the entrance and exit of the analysis section 4 constant, the amount of sample gas sucked into the analysis section 4 can be adjusted to a constant value. Furthermore, during calibration, the calibration gas pressure correction means 11 corrects the pressure of the calibration gas by reducing the pressure in accordance with the pressure of the sample gas, so that the analysis section 4 can be calibrated accurately.

Note that the drive air pressure adjustment means 8, differential pressure adjustment means 9, sample gas pressure adjustment means 10, and calibration gas pressure correction means 11 according to the present invention are not limited to those described in the specific example of FIG. 2 above.

<Effect of the idea> According to the present invention, the following effects are achieved.

Compared to diaphragm pumps, ejector pumps are smaller, lighter in weight, consume less power, have less vibration, do not pulsate, and are cheaper. Therefore, there is no need to take special measures such as placement, which is required when using diaphragm pumps. The entire structure can be made compact and simple. Furthermore, unlike diaphragm pumps, ejector pumps do not require a motor and do not have moving parts such as a diaphragm, so maintenance cycles can be extended. Furthermore, since an ejector pump is used, the degree of freedom in piping can be increased compared to the case of a diaphragm pump.

Moreover, as described in the examples, the driving air pressure adjustment means, the differential pressure adjustment means, the sample gas pressure adjustment means, and the calibration gas pressure correction means solve the problem that may occur due to the use of the ejector pump. can do.

Therefore, it is possible to provide a gas analyzer that has a simple structure, can be made compact as a whole, and can perform accurate measurements.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of the gas analyzer of the present invention. FIG. 2 is a configuration diagram of a gas analyzer according to an embodiment of the present invention. 3 and 4 are functional block diagrams of a conventional gas analyzer. 4... Analysis section, 7... Ejector pump, 8...
Driving air pressure adjustment means, 9...Differential pressure adjustment means,
10...Sample gas pressure adjustment means, 11...Calibration gas pressure correction means.

Claims (1)

[Scope of Claim for Utility Model Registration] A gas analyzer configured to supply a sample gas from a sample gas discharge source to an analysis section through an analysis line, and also to supply a calibration gas to the analysis section, wherein the analysis section in the analysis line an ejector pump disposed downstream of the installation position of the sample gas for sucking the sample gas; a driving air pressure adjustment means for adjusting the pressure of the air for driving the ejector pump to a constant level; and a sample gas from the sample gas discharge source. sample gas pressure adjustment means for adjusting the variation in the discharge pressure of the sample gas to a constant level; differential pressure adjustment means for adjusting the differential pressure between the inlet and outlet of the analysis section to a constant value; A gas analyzer comprising: a calibration gas pressure correction means for correcting the pressure reduction to correspond to the pressure of the gas;