JPH0815150A - Gas concentration measuring apparatus - Google Patents

Abstract

PURPOSE:To continue measurement automatically for a long time, while grasping the drift or fluctuation of sensitivity at the time of calibration, by outputting the designated value of a printer or the difference between the designated value and the concentration of standard gas to a printer immediately before the standard gas is introduced to an analyzing section and calibrated. CONSTITUTION:At the time for performing calibration, a calibrating section 6 commands to switch the gas being introduced to an analyzing section 2 from a sample gas to a standard gas. When a zero gas is initially introduced as the standard gas, a detection signal is fetched from the analyzing section 2 upon elapse of a predetermined time after introduction of the zero gas and a detection value, i.e., a value designating the output of a printer 4, is delivered to the printer 4. It is then corrected such that the output of the printer 4 is designated to zero before ending calibration with the zero gas. Subsequently, the standard gas is switched to a span gas and the detection value is similarly stored in the printer 4. The designation value for the printer 4 is then corrected according to the concentration value of the span gas before ending calibration with the span gas.

Description

Detailed Description of the Invention

[0001]

The present invention relates to N in exhaust gas and environmental gas.
The present invention relates to a gas concentration measuring device for continuously measuring Ox, CO, CO ₂ , methane, O _2, etc. for a long time.

[0002]

2. Description of the Related Art Such a gas concentration measuring device is provided with a sample gas introducing section and a standard gas introducing section for calibration, and an analyzing section for continuously measuring the concentration of a specific component in the sample gas for a long time, A printer that prints the measurement data output from the analysis unit, and switches the gas introduced to the analysis unit from the sample gas to the standard gas for a certain period of time at a predetermined time, and corrects the indicated value of the printer according to the standard gas concentration. A calibration unit for automatically performing calibration is provided. In order to continuously analyze the specific gas component for a long time, the recording paper feed speed of the printer (referred to as chart speed) is a low speed such as 2 cm per hour. If the measurement is continued for a long time, the zero point will change or the sensitivity will change.Therefore, zero gas containing no measurement component and span gas containing the measurement component at a known concentration are regularly or irregularly used. It is necessary to introduce into the analysis section and calibrate so that the printer's instructions are at the predetermined zero point and span point.

When the sample gas is introduced into the analysis section and the measurement is continued for a long time and the measurement data is recorded in the printer, the measurement data is recorded as indicated by a as shown in FIG. When the gas introduced into the analyzer for calibration is switched to zero gas, a peak b indicating zero gas is recorded, and when a span gas is subsequently introduced, a peak c corresponding to the span gas concentration is recorded. After that, the sample gas is switched to and the measurement is continued. In the calibration, after the zero gas is flown, the indicated value of the printer is corrected to a predetermined zero level, and when the span gas is passed, the indicated value of the printer is corrected to the predetermined span gas concentration.

[0004]

When looking at the result of the printer as shown in FIG. 1, the change of the instruction of the printer during the introduction of the standard gas when the standard gas is introduced and the calibration and the instruction before and after the calibration are shown. It is difficult to know how much it has been modified by just looking at the print results of the printer. This is because the calibration time is several minutes to several tens of minutes, which is shorter than the measurement time, and the chart speed of the printer is set to about several cm per hour.

The conditions before and after the calibration represent drift and sensitivity changes, but it is not possible to know how much drift and sensitivity changes have occurred in the conventional measuring apparatus just by looking at the printer's records. It is an object of the present invention to provide a gas concentration measuring device that automatically continues measurement for a long time so that drift and sensitivity changes can be recognized in calibration.

[0006]

FIG. 2 schematically shows the present invention. The calibration unit 6 causes the printer 4 to output the instruction value of the printer 4 immediately before the calibration when introducing the standard gas into the analysis unit 2 or the difference between the instruction value of the printer 4 immediately before the calibration and the standard gas concentration. .

[0007]

The calibration operation of the present invention will be described with reference to FIG. At the time of calibration, the gas introduction into the analysis unit 2 is switched from the sample gas to the standard gas according to an instruction from the calibration unit 6. The zero gas is first introduced as the standard gas, and the span gas is introduced after the calibration with the zero gas is completed. However, the order may be reversed, or either one of the calibrations may be performed.

Explaining zero gas, after a certain time has elapsed after introducing zero gas, a detection signal from the analysis unit 2 is fetched and the detected value, that is, an instruction value to be output by the printer 4 is sent to the printer 4 and output. . FIG.
In the example of (B), the printer 4 is made to record numerically that the instruction at the time of introducing the zero gas was -5.1. After that, the printer's indicated value is corrected to zero, and the calibration with zero gas is completed.

Next, the standard gas is switched to the span gas,
Similarly, the detected value (instructed value) of the span gas is stored in the printer. In the example of FIG. 3B, it is recorded numerically that the instruction at the time of introducing the span gas was 101.2. After that, the instruction value of the printer is corrected according to the span gas concentration value, and the calibration with span gas is completed.

[0010]

EXAMPLE FIG. 4 schematically shows an example. Reference numeral 2 denotes an analysis unit that includes a sample gas introduction unit and a calibration standard gas introduction unit and continuously measures the concentration of a specific component in the sample gas for a long period of time. ,
A CPU 10 is provided as a control unit that controls the operation of introducing standard gas and performing calibration. The CPU 10 includes an input unit 12 for setting the chart speed of the printer 4,
A storage unit 14 for storing measurement data and chart speed and an output unit 16 for outputting measurement data and chart speed are connected to the printer 4.

In addition to the CPU 20, the printer 4 includes an input unit 22 for inputting measurement data and chart speed instructions sent from the output unit 16 of the analysis unit, and a printing unit 24 for printing measurement data and calibration data. In addition, a storage unit 26 for storing the chart speed is provided so that the printer 4 itself can change the chart speed.

The CPU 10 realizes the calibration unit 6 shown in FIG. 2, and as a basic function, the calibration operation shown in FIG. 3 and the detected value (instructed value) data immediately before calibration during calibration or The function to print the difference between the standard gas concentration value and its detected value is realized.

From the situation of the change of the instruction of the printer when the standard gas is introduced at the time of calibration, it takes longer than expected to stabilize the instruction, or the difference (drift) between the actual concentration of the standard gas and the instruction is a predetermined value. If it is larger than the above, there is an abnormality in the sampling system or an abnormality in the detection unit. However, when recording at the same chart speed during calibration and sample gas measurement, it is difficult to understand the change in the instruction during calibration. Therefore, if the chart speed is changed so as to be increased at the time of calibration, it becomes easy to grasp the change in the instruction at the time of calibration.

Therefore, the operation shown in FIG. 5 is such that the chart speed can be automatically changed at the time of calibration. As shown in FIG. 5 (A), while measuring the sample gas and outputting or printing the measured data, when the time to calibrate comes, introduction of the standard gas is started (step ST1), and the current chart speed is changed. Stored in the storage unit 14 (step ST
2). When the chart speed at the time of measuring the sample gas is slow, for example, 2 cm per hour, the chart speed is changed to be faster (steps ST3 → ST4). If the chart speed is originally set high, the chart speed is not changed.

When the calibration is completed and the introduction of the standard gas is completed (step ST5), the original chart speed stored in the storage unit 14 is restored (step ST6). The chart speed is not changed during normal measurement of sample gas and introduction of standard gas.

The operation of FIG. 5A can also be realized in the printer 4. In this case, the standard gas introduction start signal and the introduction end signal are received from the analysis section at the input section 22,
If the chart speed is slow, the CPU 20 instructs the chart speed to be increased only during the calibration period.
In this case, the original slow chart speed is stored in the storage unit 26 and is returned to the slow chart speed after the calibration is completed.

As described above, since the chart speed is increased during calibration, the printer records clearly the change in the indicated value accompanying the introduction of the standard gas during calibration as shown in FIG. 5 (B). It In FIG. 5B, the change in the instruction at the zero point and the change in the instruction at the span point are the changes due to the correction of the instruction value by the calibration. The instruction value immediately before the calibration is printed near the position where the instruction value changes at the time of calibration.

As shown in FIG. 1 or FIG. 3B, when recording at the same slow chart speed as during sample gas analysis during calibration, the calibration peak may be mistaken for a noise peak. . In order to clearly show that the peak is at the time of calibration, one method is to continue introducing the standard gas for a certain time after completion of the calibration and clearly show that the peak is at the time of calibration. is there. However, for that purpose, the amount of standard gas used increases. Therefore, FIG. 6 shows an embodiment in which the data immediately after the calibration is held for a certain period of time so that the fact that the calibration is actually performed can be clearly recorded on the printer.

As shown in FIG. 6A, the measurement data is stored in the storage unit 14 immediately after the calibration is performed (step S
T11 → ST12). The measured data is replaced with the stored data until a fixed time elapses after the calibration is performed (step ST
13 → ST14), the hold operation is performed so that the stored data is recorded in the printer as the measurement data.
This operation is performed both during calibration with zero gas and during calibration with span gas. As a result, the printer is shown in FIG.
The standard gas readings are recorded over time, as shown in (B).

In FIG. 6, the time for holding the indicated value of the standard gas at the time of calibration is not limited to a method of predetermining it to be a fixed time, but the calibration should be clearly performed on the printer in relation to the chart speed. It may be possible to set the optimum time in consideration of the chart speed, so that the recording is left to such an extent that the value can be understood.

In FIGS. 3 (B), 5 (B) and 6 (B), the position where the detection value (instruction value) of the standard gas immediately before the calibration is printed is the output position of the data obtained by measuring the sample gas. Any position that does not overlap can be used, as shown in FIG.
It may be outside the frame where the peak is recorded as in (B). As shown in FIG. 5 (B) and FIG. 6 (B), the indicated value by the zero gas is near the recording position by the zero gas and depends on the span gas. The indicated value may be printed near the recording position of the span gas. Further, instead of printing the detected value (instructed value) of the standard gas immediately before calibration, the difference between the detected value (instructed value) and the actual concentration of the standard gas may be printed.

The present invention includes the following aspects. (1) At the time of calibration, the chart speed is changed so as to be higher than the chart speed during measurement of the sample gas. This makes it possible to better understand the change over time in the instruction accompanying the introduction of the standard gas during calibration, and it becomes easy to determine the abnormality of the sampling system or the abnormality of the detection unit. (2) Hold the measurement data of the standard gas immediately after the calibration for a fixed time or an appropriate time according to the chart speed.
This makes it easy to confirm that the calibration has been performed even when the chart speed is not changed during the calibration.
Further, the amount of standard gas used can be reduced as compared with the case where the standard gas is continuously introduced for a certain period of time.

[0023]

According to the present invention, in the gas concentration measuring device for continuously measuring automatically, the printer instruction value immediately before the calibration or the printer instruction value immediately before the calibration when the standard gas is introduced into the analysis portion to perform the calibration. Since the difference between the standard gas concentration and the standard gas concentration is output to the printer, it is easy to understand the drift and the sensitivity change in the calibration.

[Brief description of drawings]

FIG. 1 is a diagram showing a recording example of a printer in a conventional measuring apparatus.

FIG. 2 is a block diagram schematically illustrating the present invention.

FIG. 3 is a diagram showing a calibration operation in the present invention,
(A) is a flow chart, and (B) is an output example of the printer.

FIG. 4 is a block diagram showing an example.

FIG. 5 is a diagram showing an operation in another embodiment,
(A) is a flow chart, and (B) is an output example of the printer.

6A and 6B are diagrams showing an operation in still another embodiment, in which FIG. 6A is a flow chart and FIG. 6B is an output example of the printer.

[Explanation of symbols]

 2 analysis unit 4 printer 6 calibration unit 10 CPU of analysis unit 12 input unit of analysis unit 14 storage unit of analysis unit 16 output unit of analysis unit 20 CPU of printer 22 input unit of printer 24 print unit of printer 26 storage unit of printer

Claims (1)

[Claims] 1. An analysis unit comprising a sample gas introduction unit and a calibration standard gas introduction unit for continuously measuring the concentration of a specific component in the sample gas for a long time, and measurement data output from the analysis unit. And a printer that prints out the gas to be introduced into the analysis unit at a predetermined time from the sample gas to the standard gas for a certain period of time, and automatically calibrates the printer to correct the indicated value according to the standard gas concentration. In a gas concentration measuring device including a calibration unit, the calibration unit introduces a standard gas into the analysis unit to perform a calibration, a printer instruction value immediately before calibration, or a printer instruction value and a standard gas concentration immediately before calibration. The gas concentration measuring device is characterized in that the difference between the two is output to a printer.