JPH09311051A - Range changeover device and gas analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically perform an optimum range changeover in a gas analyzer, by which a gas concentration is output as an integrated value. SOLUTION: A gas concentration is integrated and computed in every sampling time (ST3, ST4). When the integrated value of the sampling time is at 90% or higher of a full scale, a range is changed to another low range whose sensitivity is lowered by one grade (ST5, ST6). When the number of times of sampling operations reaches a prescribed value, i.e., when an integrating and computing operation is finished, a range is changed to another one whose sensitivity is higher by one grade when a final integrated value is at 70% or lower of the range whose sensitivity is higher by one grade (ST7, ST8, ST9).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a range switching device such as a gas analyzer for measuring combustion exhaust gas or atmospheric gas.

[0002]

2. Description of the Related Art Analysis results of a gas analyzer are recorded by, for example, a recorder. In this case, if the output signal range is not appropriate, the scale will be over, or conversely, the level will be too small and the change will not be sufficiently recorded. Therefore, it is necessary to always set the range appropriately. The range setting of the conventional gas analyzer has been performed by the person who uses the meter estimating the gas concentration of the measurement object and manually setting the range, or by using the instantaneous gas concentration, it is automatically set at any time.

[0003]

Some gas analyzers are designed to sequentially integrate the measured gas concentration, not instantaneous values, over a plurality of sampling times at predetermined intervals, that is, to output the integrated values. is there. In the gas analyzer of this type, when the automatic range switching using the instantaneous value is performed as in the conventional case, if the value at the end of integration and the instantaneous value at that time are different from each other, the optimum range cannot be adopted. Further, due to the nature of the integration calculation, there is a problem that the value is small immediately after the calculation is started and the setting range becomes unstable if the range is automatically switched at any time.

The present invention has been made in view of the above problems, and provides a range switching device and a gas analyzer which can always automatically set an appropriate range even when outputting an integrated value. It is an object.

[0005]

A range switching device according to claim 1 of the present application claims, in a predetermined cycle,
In a signal output device that sequentially integrates input signals of multiple sampling times in each cycle and outputs the average value of the input signals of the cycle, switch to the lower sensitivity range when integrating each sampling time. First determination means for determining whether or not to perform it and second determination means for determining whether or not to switch to a higher sensitivity range at the end of the integration calculation in each cycle are provided. The range is automatically switched according to the discrimination result of the first discriminating means and the second discriminating means.

The gas analyzer according to claim 2 employs the range switching device according to claim 1. In this range switching device, the optimum range is automatically set using the integrated value. Further, the switching to the low sensitivity range determined by the first determination means is changed at every sampling time, and the switching to the high sensitivity range determined by the second determination means ends the integration time. Only shifts in time.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a block diagram of a gas analyzer according to an embodiment of the present invention. In FIG.
Exhaust gas, atmospheric gas, and the like to be analyzed are input to the gas analyzer 4 through the filter 1, the pump 2, and the gas flow path 3. Since the analysis result is output as an analog signal, it is amplified by the amplifier 5, converted into a digital signal by the A / D converter 6, and integrated by the CPU 7. The integrated value is output as a data to the recorder 8, for example. Given.

When continuously measuring nitrogen oxides, sulfur oxides, etc. contained in the atmosphere, it is not realistic to set the range manually according to the concentration that changes from moment to moment, and automatically. It is desirable to set to the optimum range. When managing the concentration data with integrated values for a certain period of time, it is necessary to automatically set the range using the integrated values. However, since the integrated value starts from the point where the concentration is zero, the average value of that time is output after a certain period of time, so if the range is simply switched using the integrated value, the range changes too much, Data cannot be recorded well. Therefore, in the gas analyzer of this embodiment, the timing is changed when changing to a range with high sensitivity and when changing to a range with low sensitivity. In other words, when changing to a range with low sensitivity, monitor the range at intervals of several tens of seconds, and change to a range with high sensitivity only when the integration calculation is completed and the value becomes the largest. ing. By doing this, even if the value becomes zero at the start of integration calculation,
The optimum range can be set without shifting to the highest sensitivity range. Such processing is executed by the CPU 7.

Here, the term "integral" means that the sampled data is Xi within a certain set time (every fixed period).
(I = 0 to N) is added and divided by the total number of samples N in time, and the integrated value is

[0010]

[Equation 1]

It is represented by Therefore, the integrated value at the end of the integration calculation (k = N) is the average value of the time. FIG. 2 shows an example of changes in the integrated value when the integration is performed every hour. Next, the automatic range switching operation in the gas analyzer of the embodiment will be described with reference to the flowchart of FIG.

In the following description, the integration period is 5 minutes and the sampling time is 15 seconds. When the operation starts, the integration calculation is started (step ST1), and the variable N is set to 1 (step ST2). This variable N is used to count the number of samplings within the integration calculation cycle. It waits until the sampling time of the 15-second interval arrives (step ST3). When the sampling time arrives, the output of the gas analyzer 4 at that time, that is, the gas concentration is integrated with the integrated value up to that point (STST ST
4). As this integrated value, a value obtained by sequentially integrating the values obtained by dividing the density at that point by the number of sampling times N is stored.

Next, in step ST5, is the integrated value 90% or more of the full scale? Is determined (first determining means). If the judgment is YES, that is, the integrated value is 9 of full scale.
If it is 0% or more, it should be switched to a low sensitivity range, and one range is changed to a low sensitivity range (step S
(T6), and proceeds to the next step ST7. If the integrated value is less than 90% of the full scale, the range is not changed and the process proceeds to step ST7.

At step ST7, is N = 20? Is determined. In this determination, it is determined whether or not the integration calculation is completed. If 5 minutes have passed since the integration calculation was started, N
= 20, and the integration has ended, but the variable N is 20
If it has not reached, it is the stage where the integration is continued every 15 seconds, and the variable N is set to 1 when the judgment in step ST7 is NO.
Increment (step ST8), step ST
Return to 3. After that, every time the sampling time arrives,
The process of step ST3, ..., Step ST8 is repeated. That is, the integration is continued.

When the determination in step ST7 is YES,
That is, when N = 20, it means that the integration calculation end time has arrived. Here, the process proceeds to step ST9, and the last integrated value (concentration average value because it is divided by N = 20) has one high sensitivity range. 70% or less? Is determined (second determining means). If the determination is YES, that is, if the integrated value is 70% or less of one high-sensitivity range, the range should be switched to the higher-sensitivity range, and the range is changed to the higher-sensitivity range (step ST10). Move. If the determination is NO in step ST9, that is, if the integrated value exceeds 70% of the range in which one sensitivity is high, the range is not changed and the process proceeds to step ST11.

In step ST11, the accumulated value up to that point is cleared, the process returns to step ST1, and the next accumulated calculation is performed. When changing the range, the CPU 7 outputs the data indicating that the range is changed and the integrated value in the changed range to the recorder 8.

[0017]

According to the present invention, when the data is handled as the integrated value, the optimum range is set by the integrated value without depending on the instantaneous value, so that, for example, the output to the recorder is saturated,
The resolution is not bad. In addition, the range with low sensitivity is determined at each sampling time, or the range with high sensitivity is changed at the end of integration, so the range is not changed more than necessary and the recorded data looks good. Get better.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a gas analyzer according to an embodiment of the present invention.

FIG. 2 is a diagram showing an integration cycle in the gas analyzer of the same embodiment,
It is a figure which shows an example of the relationship of integrated density.

FIG. 3 is a flowchart for explaining an automatic range changing operation of the gas analyzer of the same embodiment.

[Explanation of symbols]

 3 gas flow path 4 gas analyzer 5 amplifier 6 A / D converter 7 CPU 8 recorder

Claims (2)

[Claims] 1. A signal output device for sequentially accumulating input signals of a plurality of sampling times in each cycle and outputting an average value of the input signals of the cycle, at the time of integration calculation of each sampling time. First determination means for determining whether or not to switch to the lower sensitivity range, and to determine whether or not to switch to the higher sensitivity range at the end of the integration calculation in each cycle. A range switching device comprising a second discriminating means, and the range is automatically switched according to the discrimination results of the first discriminating means and the second discriminating means. 2. A gas analyzer which analyzes an input gas, sequentially integrates the analysis results for each predetermined cycle into a plurality of sampling times in each cycle, and outputs an average value of the analysis results of the cycle. In the above, in the integration calculation of each sampling time, the first determination means for determining whether or not to switch to the lower sensitivity range, and at the end of the integration calculation in each cycle, switch to the higher sensitivity range A gas analyzer characterized in that it is provided with a second discriminating means for discriminating whether or not to perform, and the range is automatically switched according to the discrimination results of the first discriminating means and the second discriminating means, respectively. apparatus.