JPH07318556A - Combustion exhaust gas concentration measuring apparatus - Google Patents

Abstract

PURPOSE:To correct the measurement of the concentration of a specific component positively and automatically through a simple means by making a switching to a predetermined reference O2 concentration depending on the kind of fuel determined automatically based on the detection values of O2 and CO2 CONSTITUTION:A fuel kind decision section 8 calculates a characteristic value representative of the kind of fuel based on the measurements of O2 and CO2 in an combustion exhaust gas measured by means of an O2 meter 4 and a CO2 meter 6 and then determines the kind of fuel based on the characteristic value. The characteristic value is 19-20 for the exhaust gas produced from an incineration facility, about 16 for liquid fuel such as fuel oil, and 12-34 for gas fuel. When a reference O2 concentration switching section 10 makes a switching to a reference O2 concentration determined depending on the kind of fuel thus determined, a correcting section corrects the concentration Cs of a specific component measured by a specific component detector 2 according to a predetermined formula using a measurement of the O2 meter and a reference concentration On being employed. This constitution can set the reference concentration On positively without increasing the cost of the measuring apparatus.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a NOx measuring device, SO ₂
The present invention relates to a device for measuring a specific component in combustion exhaust gas, such as a measuring device or a CO measuring device.

[0002]

2. Description of the Related Art Among NOx measuring devices among combustion exhaust gas measuring devices, the NOx measured value is corrected by the coexisting O ₂ concentration. If the NOx measurement value is Cs, the correction is performed based on the following equation. C = {(21-On) / (21-Os)} Cs Here, On is a reference O ₂ concentration, which is determined for each fuel type and combustion facility (these are collectively referred to as fuel type). Os is an O ₂ measurement value measured at the same time as NOx,
C is the corrected NOx value.

Reference O ₂ concentration (On value) depending on fuel type
Must be changed. Conventionally, in a combustion facility where a plurality of types of fuels are switched and used, in a stationary (stationary) NOx measuring device, a reference O is set on the measuring device.
_{2 The} concentration is reset, or switching is performed based on the switching signal from the central operating room. In the portable NOx measuring device, the reference O ₂ concentration is manually switched or reset.

[0004]

The method of switching the reference O ₂ concentration by a switching signal from the outside can be adopted only in a facility which can generate the switching signal like a stationary type. If such a switching signal is input from the outside, the device cost will be high. Further, if the reference O ₂ concentration is manually switched, there is a problem of lack of certainty.

In the SO ₂ measuring device and the CO measuring device, it is not obligatory to correct the measured specific component concentration in the exhaust gas by the coexisting O ₂ concentration, but there is a demand. Even if the SO ₂ measuring device or the CO measuring device tries to perform the correction based on the coexisting O ₂ concentration, the same problem as the NOx measuring device occurs.

According to the present invention, the fuel type is automatically determined from the combustion exhaust gas and the reference O ₂ concentration is automatically switched, so that the apparatus cost is not increased and the reference O ₂ concentration is reliably switched. The purpose is to be able to.

[0007]

FIG. 1 shows the present invention. Specific component detector 2 for detecting the concentration of a specific component in combustion exhaust gas
Is a NOx meter, SO ₂ meter or CO meter. 4 is an O ₂ meter for detecting the O ₂ concentration in the exhaust gas, and 6 is C in the exhaust gas.
It is a CO ₂ meter that detects the O ₂ concentration. Fuel type determining unit 8 calculates the characteristic value representing the fuel type from the CO ₂ measurements by O ₂ measurement and CO ₂ meter 6 by O ₂ four, determines the type of fuel on the basis of the characteristic values. The reference O ₂ concentration switching unit 10 sets a reference O ₂ concentration according to the determined fuel type.
Adopt _two concentrations. Correcting unit 12 based on the relational expression C = established {(21-On) / ( 21-Os)} Cs (1), using O ₂ measurements and the adopted reference O ₂ concentration by the O ₂ four Then, the specific component concentration measurement value by the specific component detector 2 is corrected.

[0008]

The oxygen concentration Os (x) contained in the exhaust gas and the CO ₂ concentration (y) coexisting in the exhaust gas depend on the type of fuel.
There is a relationship as shown in. This relationship is represented by a linear relationship of y = -ax + b =-(b / 21) x + b (2) as an example. The b value corresponds to the intercept in FIG. 2, but can be obtained in advance depending on the fuel type. For example, it is about 19 to 20 for exhaust gas generated from a refuse incineration facility, about 16 for liquid fuel such as heavy oil, and about 12 to 14 for gas fuel. The fuel type determination unit 8 obtains the b value from the above relational expression (2) using the O ₂ value (x) and the CO ₂ value (y) measured at the same time,
The fuel type is determined depending on which fuel type the b value is closest to. The numerical value corresponding to the intercept should be set from the measured value.

On the other hand, in the NOx measuring device, the standard O ₂ concentration (On) is stipulated by law according to the fuel type. The standard O ₂ concentration is 4 for exhaust gas from a liquid fuel such as heavy oil, 5 for exhaust gas from a gas fuel, 6 for exhaust gas from a solid fuel, and 13 for exhaust gas from a refuse incineration facility. Based on the determination value b calculated by the fuel type determination unit 8, the reference O ₂ concentration switching unit 10 adopts the reference O ₂ concentration of the fuel type corresponding to the determination value. The correction unit 12 corrects the measurement value Cs of the specific component detection unit 2 using the adopted standard O ₂ concentration and the measured O ₂ value, and outputs the corrected value Cs.

Taking a NOx meter as an example, the operation is as shown in the flowchart of FIG. As a specific example, the measured O ₂ concentration (x) is 3% and the measured C is
If the O ₂ value (y) is 14%, then b = 16.3 from equation (2), and it is determined that this fuel type is heavy oil. Then, 4 is adopted as the reference O ₂ concentration (On) at that time, and the measured NOx value is corrected by the equation (1). When the present invention is applied to an SO ₂ meter or a CO meter instead of the NOx meter, the measurement values are corrected in exactly the same manner.

[0011]

Embodiment FIG. 4 schematically shows an embodiment. The conversion NOx calculator 20 has a built-in CPU, and the fuel type determination unit 8 and the reference O ₂ concentration switching unit 1 in FIG.
0 and the function of the correction unit 12 are realized. NOx
In the measuring device, the NOx meter 2 and the O ₂ meter 4 are already provided, and the CO ₂ meter 6 is newly provided in this. As the NOx meter 2, for example, a chemiluminescence type NOx meter,
A magnetic O ₂ meter is used as the O ₂ meter 4, and an NDIR (non-dispersive infrared spectrophotometer) is used as the CO ₂ meter 6. All of these measuring instruments are commonly used. The converted NOx calculator 20 can be realized by applying a program having the function of FIG. 1 to a CPU system used as a control device of a NOx measuring device.

The present invention has the following aspects. (1) When the O ₂ concentration measurement value is x and the CO ₂ measurement value is y, the fuel type determination unit 8 calculates the b value by y = − (b / 21) x + b, and the b value is predetermined. The fuel type is determined by comparing it with the b value for each gas type, and the reference O ₂ concentration switching unit 10 adopts a predetermined reference O ₂ concentration according to the determined fuel type. The correction unit 12 sets the reference O ₂ concentration to On,
When the measured O ₂ value is Os and the measured value by the specific component detection unit 2 is Cs, the correction is performed by C = {(21−On) / (21−Os)} Cs. The value of b is determined and set in advance for each combustion type. (2) The specific component detection unit 2 is a NOx meter. As a result, the NOx measurement device, which is currently required by law, can automatically correct the NOx measurement value.

[0013]

According to the present invention, the O ₂ value and the CO ₂ value are detected simultaneously with the detection of the specific component such as NOx, and the O ₂ detected value and the C value are detected.
Since the fuel type is automatically determined using the O ₂ detected value, and the predetermined reference O ₂ concentration is automatically switched according to the determined fuel type, the measured value of the specific component The correction can be realized automatically and by simple means. As a result, it becomes possible to surely perform the correction without increasing the apparatus cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing the present invention.

FIG. 2 is a diagram showing a relationship between an O ₂ concentration and a CO ₂ concentration in each fuel type.

FIG. 3 is a flowchart showing the operation of one embodiment.

FIG. 4 is a block diagram schematically showing an embodiment.

[Explanation of symbols]

2 Specific component detection section 4 O ₂ meter 6 CO ₂ meter 8 Fuel type determination section 10 Reference O ₂ concentration switching section 12 Correction section 20 Conversion NOx calculator

Claims (1)

[Claims] 1. A specific component detector for detecting the concentration of a specific component in combustion exhaust gas, an O ₂ meter for detecting the O ₂ concentration in the exhaust gas, and a CO ₂ meter for detecting the CO ₂ concentration in the exhaust gas. , C by the CO ₂ meter and O ₂ measurements by the O ₂ meter
A fuel type determination unit that calculates a characteristic value representing the fuel type from the O ₂ measurement value and determines the fuel type based on the characteristic value, and a criterion O determined according to the determined fuel type
Analyte concentration by the specific component detector with the reference O ₂ concentrations switching unit employing the ₂ concentration, based on a defined relationship, the O ₂ measurement and adopted criteria O ₂ concentration by the O ₂ meter A flue gas concentration measuring device comprising: a correction unit that corrects a measured value.