JPH0480642A - Infrared gas analyzer - Google Patents

Abstract

PURPOSE:To compensate a nonlinear change due to each of an interference component gas concentration and an ambient temperature and thereby to improve the precision in measurement by a method wherein a compensated value of the ambient temperature and a compensated value of an interference error of the interference component gas concentration due to the ambient temperature are determined by computation. CONSTITUTION:A temperature sensor 22 detects the ambient temperature of the main body 2 of an analyzer and outputs a temperature signal 22a. An arithmetic element 23 receives a detection signal 13a and the temperature signal 22a as inputs, executes a prescribed computation and outputs the result of the computation as an intermediate signal 23a. An arithmetic element 24 receives a detection signal 15a and the temperature signal 22a as inputs and outputs an intermediate signal 24a by a prescribed computation. Even when a measured value shown by each of the detection signals 13a and 15a is a value changing in a nonlinear manner in accordance with the temperature, a computed value is compensated with high precision by an error compensation signal 27a. Therefore the concentration of a component gas to be measured can be measured with high precision without containing both of a temperature error and an interference error substantially.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a non-dispersive single-beam double-beam infrared gas analyzer;
In particular, the present invention relates to an analyzer that can reduce both measurement errors due to interfering component gases in a sample gas and measurement errors due to the ambient temperature of the infrared gas analyzer being different from a reference value.

[Conventional technology]

Figure 2 is a configuration diagram of the conventional non-dispersive type single light #A restored Tobu infrared gas analyzer 1. The analyzer body 2 in Figure 1 is "Fuji Jiho" published by Fuji Electric Co., Ltd., Vol. 50, Ta No. 7, pp. 36 ~
43 (Hereinafter, this document may be referred to as the Fuji Electric Literature Department.) (This is the same as the one shown in Figure 3 in the "infrared gas analyzer" described.

In Fig. 2, 3 is an infrared ray 5 which cuts off the infrared rays emitted from the infrared light source 4, which is a single light source.
A single point chi1 brim designed to emit light,
6 is the infrared ray 5 as two luminous fluxes 5a.

5b [separated, and one beam 5 is made incident on the sample cell 9 into which the sample gas 8 is introduced from the gas lower, and the other beam 5 is
A reference cell 10 filled with, for example, an inert gas that does not absorb infrared rays 5 (distribution cell in which the infrared rays 5 are incident); 13 is a light source section comprising the above-mentioned Chifutsuba 3, light source 4, and distribution cell 6. Reference numeral 13 is filled with gas of the same type as the measurement component gas Gm whose temperature is to be measured by this analyzer 1; Transmitted light 5C of the light flux 51 transmitted through the sample cell 9 and transmitted light 5 of the light flux 5b transmitted through the reference cell 10.
d and the measurement component gas GrnC in the sample gas 8 introduced into the sample cell 9.
A first detection signal representing the 111J constant value Sl, which is the sum of the main measurement value E based on the absorption of the luminous flux 51 by the interference component gas Gi in the sample gas 8, and the sub-measurement value E based on the absorption of the luminous flux 5m by the interference component gas Gi in the sample gas 8. 131 appears (first detection!), 15 is the measurement error of the measurement component gas Gm due to the presence of the interference component gas Gi in the sample gas 8. The transmitted light 5C is filled with a gas to compensate for the temperature difference (sometimes referred to as Et), and the transmitted light 5C is transmitted through the first detector 13, and the transmitted light 5d is transmitted through the first detector 13. The first detector output light 16 consisting of the light 5f is incident, and the sample gas 8
The second measured value S! is based on the absorption of the luminous flux 5a by the interference e in the middle gas Gi, the second measured value S! The analytical needle main body 2 described above is composed of the above-mentioned light source section 12, cell section 11, and detection Sta and 15.

17 is a linear amplifier that has a gain of 1 and receives the signal 131; 18 has a gain of 8 and receives the signal 15;
19 is a 1m1f compensation calculator that multiplies the value represented by the output signal of the amplifier 17 by (1/(1+AIT)) and outputs a signal 19a representing the result vl. 20 is the value represented by the output signal of the amplified first g by +1/(1+T)1, and the result is V! This is a temperature compensation performance device that outputs a signal 201 representing the temperature.

Then, enter here 1. A2 represents a temperature coefficient as a known constant measured in advance.

Further, T indicates the difference ("o) between the ambient temperature t between the analyzer main body 20 and the reference value t of this temperature ft. 2t in FIG. 2 is the input of the calculator output signals 19m and 203, And the power level of each of these rain input power signals tLv1.V!
The infrared gas analyzer 1 is a subtracter configured to output a signal 2t1 representing this V.

[1m that the invention tries to solve! 41 Since the analyzer 1 is constructed as described above, the value V represented by the subtractor output signal 2ta is expressed by equation (1).

V” ((KI Et +KI Em)/(1+AI
T) l (KI St/(1+A,'r) 1・
...(1) Therefore, 1=1. V, E1t, S2 when
t to S10E1t, S2t to S10EJ.

Each value of S20I E for V・I g2t, ·, this. Then, equation (2) is obtained.

V* = to + g1t, S2t to S10+KIEso
Kt ate --(2) Now, as mentioned above, Em@ and 8R in equation (2) are measured values based on infrared absorption by the interference component gas Gi in the sample gas 8, but in this case, E1t , S2t to S1
0, S1t, S2t to S10 are all gas Gi'
) If it does not depend on 8 degrees C11c, KI Eam=
Km SN. By setting , K, so that v6=KIE! from equation (2). @ is obtained,
In this case, E and o are the temperature C of the measurement component gas Gm in the gas 8
1, it is clear from the above-mentioned Fuji Electric literature that the temperature Cm can be measured as positive #i'C using the subtractor output signal 2t8 without including the interference error Ei.

However, in reality /ck:, as shown in Figure 3.

The measured value E @ 6 + 816 changes according to Jl, vci [each unique nonlinear shape'/c, and even at the same degree C1, the magnitude of S20 with respect to E2t and 8. Since it is customary for the magnitudes of . As shown in r, KI ES6= Kl sta at the preset reference value Cir'c of 1141j Ci.
Pc K, + K is set so that the following holds true. Therefore, 1 analyzer 1rc is C1 (C
When ir, S20(K, 8..) for E2t occurs, and the interference error Ei is insufficiently compensated for, so there is a problem that the measurement accuracy of the temperature Cm is poor.

In addition, in one analyzer 1, the first
Measured value 8 s = E t + ” s @ ambient temperature ty)
The second measured value S!, which varies linearly with the temperature coefficient AI over a wide range, and is represented by the detection signal 15! If tn varies linearly over a wide range (temperature coefficient A).

Output signal 19! S when the value V represented by is 1=1°.

The value of 3. ．． = corresponds to S20+E3° for E2t,
The value V represented by the output signal 20a is t=t, S at VC,
The value of S! . (It is clear that there is a correspondence, in this case −Ci
Set vcK1t, S2t to S10 to be sto in KI E#@= in =Cir (
Therefore, as long as C1=CI, it is possible to accurately measure the paddle degree Cm using the subtractor output signal 2t8 over a wide -9 range of t, but at the moment of refreshing, S, , S,
The calculation unit 19.
20
, S, 7') Each box S1., Sl. Various S1t, S2 of S, , S, measured at a temperature [=t, different from
From t to S10, S□, as in equation (3), A,
, A is determined.

Therefore, the analyzer IIC, which measures the temperature Cm by the subtractor output signal 2ta, becomes KIEs/(1+AIT)=! if 1=10 or [=t, Sm
/ (1+A,T) 1t, S so that one holds true
Even if S10Kt is set from 2t, Uo
or 1 (if it is 1, V, , V, are each 81
Since the value corresponding to There is a problem in that the measurement accuracy of dl f Cm is poor due to the existence of such an error El.

The object of the present invention is to almost completely compensate for the nonlinear changes caused by the interfering component gas temperature Ci and the ambient temperature t7' of the sub-measurement value Es mentioned above,
An object of the present invention is to obtain an infrared gas analyzer with high measurement accuracy for temperature Cm.

[Means to solve the problem]

In order to achieve the above object, two aspects of the present invention include: a cell section in which a sample cell and a reference cell are provided; a light source section that makes infrared rays enter the cell section; and transmitted light of the infrared rays transmitted through the cell section. The sum of the main measurement value based on the infrared ray absorption by the measurement component gas in the sample cell and the sub-measurement value based on the infrared ray absorption by the interference component gas in the sample cell. a first detector that outputs a first detection signal representing a first measurement value, which is a value;
A second measurement value is obtained based on the absorption of the infrared rays by the interference gas component gas in the sample cell in which the first detector output light as transmitted light that has passed through the first detector of the cell unit output light is incident. a second detector that outputs a second detection signal representing the nth value; and a second detector that performs a predetermined first temperature compensation calculation on the first detection signal and outputs a first intermediate signal corresponding to the n-th calculation value as a result of this calculation. a first temperature compensation means; and a second temperature compensation means for performing a predetermined second temperature compensation calculation on the n second detection signals and outputting a second intermediate signal corresponding to the second calculation value of the calculation result. , using the second intermediate signal at a predetermined temperature 7) Performing a function value calculation operation to compensate for interference error corresponding to a specific calculation value caused by the sub-measurement value in the first detection signal 9 among the first calculation values. and a function value calculation means for outputting an error compensation signal representing a value, the first and second intermediate signal temperature compensation calculations are performed when the state temperature is t. vr-When the first and second measured values respectively represented by the first and second detection signals are Stt and Szt, and the ambient temperature is a reference value t, the first and second detection signals are respectively The ratio of the first and second measured values to 8t@, 8111 and 51trc to S20 and the ratio of S20 to S2t to 82t, respectively, are the temperature difference (t-ts
) as a known higher-order formula of stt ' 8
The calculation is to estimate 5lll, s□ from 2t, the ambient temperature is the temperature around the infrared gas analyzer, and the function value calculation calculation exists between the second calculation value and the specific calculation value. The infrared gas analyzer is configured such that the calculation is performed using a known nonlinear functional relationship.

[Effect]

With the above configuration, the ratio W of S and o to 51tK
, and the ratio of St@ to S2t W! By making it a higher-order expression of it difference 'l' = (t-t.) as described later, the first and second intermediate signals are
! By setting the above functional relationship as described below, the interference error compensation value represented by the error compensation signal can be Since it can be set to 5 to almost exactly match the specific calculated value in the first calculated value,
From the difference between the value of the first intermediate signal and the value of the error compensation signal, a highly precise If measurement result with sufficiently compensated interference error Ei and temperature error Et can be obtained.

Cf1i4 Embodiment] FIG. 1 is a block diagram of a practical example of the present invention, and in this figure, the same parts as in FIG. 2 are designated by the same symbols as in FIG. 2.

In FIG. 1, 22 is a temperature sensor that detects the dark ambient temperature gt of the analyzer body 20 and outputs a temperature signal 22m representing this t, and 23 is a first detection signal 13m and a temperature signal 2.
2a are input and using these input signals (4)
A first calculation unit configured to perform calculations on the right side of the equation and output a first intermediate signal 23m representing a first calculation value "le" as a result of this calculation.

A second signal 24 receives the second detection signal 15a and the temperature signal 22a, performs the calculation on the right side of equation (5) using these input signals, and represents the second calculation value S as the result of this calculation.
A second arithmetic unit configured to output the intermediate signal 24a outputs the 2
Reference numeral 5 denotes a first temperature compensation means consisting of a sensor 22 and a calculation section 23, and numeral 26 denotes a second temperature compensation means consisting of a sensor 22 and a calculation section 24. Then, Y, -Y, and Z1 to zz in equations (4) and (5) are all constants, and T=(t-1·), in this case, the compensation means 25
．． 26 is *As mentioned above, the first and second measured values S-8
Since both weights change non-linearly according to am t
t.

S20 for S2t from S, t, S2 for S2t
Furthermore, the constant coefficients Y1 to Yp in equations (4) and (6) are provided in advance to estimate the interfering component gas temperature C! in the sample gas 8. to any constant value C1o
It was determined by conducting an experiment in which Stt was measured at each temperature of 1 by changing the temperature of the thermostat to (p + 1) m class temperatures with the temperature set to 1. Constant coefficient z, ~z qtz.

In advance, with the temperature Ci in the gas 8 set to C1o, t is (
q+1) Change to the temperature of the seed field and change the temperature t to 8. t
It was determined by conducting an experiment to measure the Then, also in this case, S2 for the coefficient Y, −Y2t
0z1 to zq are assumed to be independent of 1lfct.

81e= S1t/ (1+Y1T+Y, T +・-
−−−・−・+YpT )−(4)81t, S2t
From S10=8. t/(1+Z, T+Z, T+--...
−・・−+Z9T >−・−C5) S20=W for sl, /S2t, = 1 +Y, T+Y, T+・
...-+Y, T... (6) 82t/St@m
W, =-1+Z, T+Z, T"+--・-+ZqT ・
1t, S2t to S10, (7) Now, in FIG. 1, the compensation means 25 and 26 are configured as described above,
Let E!e be the calculated value corresponding to the calculated value S, eb''-E1. represented by the signal 23a, and let E, e be the calculated value corresponding to S20 for E2t, as 516=E2e+E3° (from the above) It's obvious.

In addition, this E3e and Szc in equation (5) change in a nonlinear shape unique to each degree Celsius depending on the zero interference component gas 1 degree Ci in the sample gas 8, so both E3° and 826 are functions of Ci. The result E, Ia is the function J (Sze) of 82t5
It is also clear from the above that it can be expressed as

Therefore, if we can know the function J, the S represented by the signal 24
Therefore, from Sle represented by the signal 23a and this Fise, we can find S20 for E2t and accurately calculate the m constant component gas IlfCm in gas B from this Eo without including an interference error of 1m. Therefore, in the present invention, J(S2.
) can be approximated by the right-most equation of equation (8), use this equation to find the interference error compensation value Eic described in equation (8) from S2e, and use this 11oc to calculate E3e in the calculated value sl,n. Please tell me to compensate you.

X in formula (8), ~Xo is lii! The ambient temperature t is 1. vc and sample gas 8 is interfering component gas G.
This was determined by conducting an experiment in which S, o, and sl were measured at each temperature Ci by changing the temperature Ci to different values of the n49 class, using a gas consisting only of i and a gas that does not absorb infrared rays. It is a constant coefficient.

E se ””J(S 2 e) ” E ic =X
IS ze+Xe52e ＋＋＋＋＋＋＋＋＋＋Xf
18. ．． --- (8) That is, in FIG. 1, 27 is the calculated value S, e! to which the signal 241 is input and which the signal 24a represents. using (8)
A function value calculating means is configured to calculate the right side of the substitution and output an error compensation signal 27 having a value corresponding to the interference error compensation value E penalty; The difference between the value Ml of the signal 27a and the value M of the signal 27a (
Ms Mt) and a signal 28 representing the result of this calculation.
In this case, the above-mentioned interference error compensation value Eic is output from the intermediate signal 2 due to the above-mentioned reason.
Since the value corresponding to the specific calculation value E3e caused by the sub-measurement value E in the detection signal 13a in the calculation value ale"E2e+E3e') represented by 3a is the value, in the end, (Ms M
The value of the subtraction means output signal 28a representing t) is the above-mentioned E26.
Each level of the signal z3a+ 271 is set to have a value corresponding to . 29 is the analyzer main body 2, moisture compensation means 25, 26, function value calculation means 27, and subtraction means 28
This is an infrared gas analyzer equipped with

Since the analyzer 29 is configured as described above.

The measured value S represented by each of the detection signals 13a and 15a,
, S, the calculated values ste'sz represented by the intermediate signals 23a and 24a, even if both of them change non-linearly according to the temperature*1<. and E2e that constitutes S1e.

E3e is always 'CS161 s, o, E*@e
It is clear that E1t and S2t give S10 K values that are very close to each other, and in this case.

It is clear that even if the specific calculated value E3e among the first calculated values S and e changes non-linearly in accordance with the temperature Ci, this calculated value E3e is compensated with high accuracy by the error compensation signal 27m. Therefore, according to this analyzer 29, the measurement component gas temperature Cm can be measured with high precision using the subtraction means output signal 28m, with almost no temperature error gt or interference error Ei included.

〔Effect of the invention〕

As described above, one aspect of the present invention includes a cell section in which a sample cell and a reference cell are provided, a light source section that makes infrared rays enter the cell section, and a cell section that emits infrared light transmitted through the cell section. The first measurement value is the sum of the main measurement value based on the absorption of infrared rays by the measurement component gas in the sample cell and the sub-measurement value based on the absorption of infrared rays by the interference component gas in the sample cell. a first detector that outputs a first detection signal representing the cell part; a second detector that outputs a second detection signal representing a second measurement value based on absorption of infrared rays; and a second detector that performs a predetermined first temperature compensation calculation on the first detection signal and responds to the first calculation value as a result of this calculation. a 111th compensation means for outputting the first intermediate signal;
a second temperature compensation means for performing a predetermined second temperature compensation calculation on the second detection signal and outputting a second intermediate signal according to the second calculation value as a result of the calculation; function value calculation means for performing a function value calculation operation and outputting a vA difference compensation signal representing an interference error compensation value corresponding to a specific calculation value resulting from the sub-measurement value in the first detection signal among the first calculation values; A non-dispersive single light source double beam infrared gas analyzer that measures the temperature of a component gas to be measured from the difference between the value of the first intermediate signal and the error compensation signal/n value, Compensation calculation is #l! When the ambient temperature is t, the first
and the first and second measured values respectively represented by the second detection signal Stt, S! When t and WR ambient humidity temperature reference value t., the first and g2 measured values respectively represented by the rc first and second detection signals are 81 @ e 8! . Toshikatsu and S8 for 81t. and the ratio of S2t [to 81t and the ratio of S2t to S10fl are both temperature difference (I
81i as expressed by a known higher-order formula of ts),
S20 to S2t from s2t, S to S2t
20, the ambient temperature is a temperature within the range of the infrared gas analyzer, and the function value calculation is a second calculation.
The infrared gas analyzer t#le was designed so that the calculation was performed using a known nonlinear functional relationship between the calculated value and the specific calculated value.

Therefore, if configured as above, Le S1 for 8 ports
° ratio W1 and S2 for s2t for S2t'/c
By setting the 0n ratio W1 to a higher-order equation of temperature difference T=(t-to) as shown in (6) and (7) 2, the first and second intermediate signals are S1@*S@, respectively. can be made to represent the IC almost exactly, and -! function value xt
Function value calculation operation in k3 means (by setting the above function relationship to be used as in (8) 2, the interference error compensation value represented by the error compensation signal is a special value among the first calculation values,
Since the VC of the present invention can be made to almost exactly (coincide) with the fixed calculated value, the interference error E1 and temperature error E<) are sufficiently calculated from the difference between the value of the first intermediate signal and the value of the !a difference compensation signal. Compensated and accurate I! II! It has the effect of obtaining measurement results.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the present invention. Figure 2 is a configuration diagram of a conventional infrared gas analyzer. FIG. 3 is a functional explanatory diagram of the infrared gas analyzer shown in FIG. 2. 1.29... Infrared gas analyzer, 5a, 5b.
...Light flux (infrared @), 9...Sample cell,
10...Reference cell. 11...Cell part, 12...Light source part, 1
3.--First detector. 13a...First detection 1 word, 14...
-・Cell part emitted light, 15 second detector, 15a...-
・Second detection signal, 16...first detector output light,
23a...First intermediate signal, 24m...
Second intermediate signal, 25...First temperature compensation means, 2
6.--M22 temperature compensation means, 27.--function value calculation means, 271.--error compensation signal. Representative Patent Attorney Yamaguchi

Claims (1)

[Claims] 1) a cell section in which a sample cell and a reference cell are provided; a light source section that makes infrared rays enter the cell section; and a light source section that transmits the infrared rays and emits light from the cell section as transmitted light that passes through the cell section; A first measurement value representing a first measurement value that is the sum of a main measurement value based on the absorption of the infrared rays by the measurement component gas in the sample cell and a submeasurement value based on the absorption of the infrared rays by the interfering component gas in the sample cell. A first detector outputs a detection signal, and the first detector output light as transmitted light transmitted through the first detector of the cell section output light is incident, and the interference component gas in the sample cell enters the first detector. a second detector outputting a second detection signal representing a second measurement value based on absorption of infrared rays; and a predetermined first detection signal for the first detection signal.
a first temperature compensation means for performing a temperature compensation calculation and outputting a first intermediate signal according to a first calculation value as a result of the calculation;
a second temperature compensation means for performing a predetermined second temperature compensation calculation on the second detection signal and outputting a second intermediate signal according to a second calculation value as a result of the calculation; and using the second intermediate signal. A function value that performs a predetermined function value calculation operation and outputs an error compensation signal representing an interference error compensation value corresponding to a specific operation value resulting from the sub-measurement value in the first detection signal among the first operation values. a non-dispersive single-light source double-beam infrared gas analyzer that measures the temperature of the measurement component gas from the difference between the value of the first intermediate signal and the value of the error compensation signal, The first and second temperature compensation calculations calculate the first and second measured values respectively represented by the first and second detection signals by S_1 when the ambient temperature is t.
_t, S_2_t and the ambient temperature is the reference value t_0.
When , the first and second measured values respectively represented by the first and second detection signals are S_1_0 and S_2_
0 and the ratio of S_1_0 to S_1_t and S_
The ratio of _S_2_0 to 2_t is the temperature difference (t
−t_0) as expressed by a known higher-order formula of S_1
The calculation is to estimate S_1_0 and S_2_0 from _t and S_2_t, the ambient temperature is the temperature around the infrared gas analyzer, and the function value calculation calculation is performed to estimate the temperature between the second calculation value and the specific calculation value. An infrared gas analyzer characterized in that the calculation is performed using an existing nonlinear known functional relationship.