SU1354074A1 - Method and device for measuring components of gas mixtures - Google Patents

Abstract

The invention relates to a technique for measuring components of gas mixtures (HS) using a gas analyzer (GA). The purpose of the invention is to increase the measurement performance. The instantaneous values of HA signals from the reference and from the analyzed HS are fixed at equal intervals of time only during the growth of these signals. Pre-register the signal HA from the zero gas in the established process. The device allows, with high performance and accuracy, to automatically measure the concentration of components of the HS. Cylinders 5-7 with GS connected to the common gas line (OGM) through i (L oo JV 4 about 4

Description

three-way electrically controlled valves (EC) 1-3. OGM is connected via a three-way EC 4, regulator of flow 8 - to the GA input. Third channels of all EC, two electrical inputs of each of which are connected to the valve switching unit, are connected to the atmosphere. This allows the BGM to be purged and the volumes from the BG to the BGM of the HS, which is then fed to the GA input. This provides the same pattern of increase in HA signals from rapper and from the analyzed HS, which allows to judge the concentration by measurements of the instantaneous values of the signals during their rise. 10 pulse generator.

one

The invention relates to an analytical technique and can be used in automated measurement systems for gas concentrations, in particular in metrology, for the certification of calibration gas mixtures.

The purpose of the invention is to improve the performance, accuracy and level of automation of measurements.

The drawing shows a diagram of the proposed device.

The device contains electrically controlled valves 1–3 installed on gas supply lines from cylinders with zero gas, a reference gas mixture and gas analysis mixtures to the common gas line, electrically controlled valve 4 installed at the outlet of the common gas line, cylinders 5 with zero gas, 6 with a reference gas mixture and 7 with analyzed gas mixtures, a flow controller 8, a gas analyzer 9, a generator of 10 pulses, analog

a go-to-digital converter 11 (ADC) valve switching unit 12, control unit 13, memory 14 (memory), set value determination unit 15, concentration calculation unit 16, measurement accuracy determination unit 17, and input / output device 18.

Control valves 1-3 are installed on the gas supply lines.

A / D converter 11 and memory 14 allow the instantaneous values of the signals to be recorded at regular intervals. The setpoint determination unit 15 allows the signal from the zero gas to be recorded in the steady state process. The BrfoK 16 concentration calculation, the measurement determination block 17 and the I / O device 18 allow determining the concentration with a given reliability and communicating the results to the operator. The control block 13 ensures the priority of operation of the device blocks. 2 sec. f-ly, 1 ill.

0

five

TO

from cylinders 5-7 to the common gas line, valve 4 is installed between the common gas line outlet and the regulator 8 inlet, the output of which is connected by a gas line to the gas analyzer inlet 9. All valves are three-way, their third gas channels are connected to the atmosphere, and the first and the second electrical inputs are connected to the outputs of block 12, the input of which is connected to the eighth output of block 13, the sixth and seventh inputs and outputs of which are connected respectively to the first output and input of the ADC 11 and the output and input of the generator 10. First, second, The third and fourth inputs and outputs of the block 13 are connected to the first outputs and inputs of the device 18, block 17, block 16 and block 15, respectively, the second inputs and outputs of which are connected to the first, second, third and fourth outputs and inputs of the memory 14, Fth the input and output of the latter are connected to the p - that output and the input of the unit 13, the sixth input is connected to the second output of the converter 11, the second input of which is connected to the electrical output of the gas analyzer .9.

The device works as follows.

During the automatic certification of gas mixtures, the certification of the i-th (1 1,2, 3, ..., n) mixture consists of m cycles

3P54074

certification Every j-th (j 1,2,.,., Dots (combinations of signals) from the second

m) the certification cycle includes a sequential flow to the input; gas analyzer 9 zero gas, the reference gas mixture, zero gas and certificate of the device 1b to the first input of the memory 14.

The operation of the device begins by the operator by filing with the first output of the device 18 to the first input of block 13 of the initial start code. After receiving this code, unit 13 purges the common gas line with zero gas. For this, from the seventh output of block 13 to the input of generator 10 a start signal is given, and the eighth output of block 13 is given a code to the input of block 12. At the same time, from the output of generator 10 to the seventh input of block 13 pulses start to flow, and to the output of block 12, the voltage level of the block 13 with the valve supply voltage is such a combination that provides a common gas purge with zero gas. The voltage is applied to the first input of valve 1 and to the second inputs of the other valves, while zero This gas passes from cylinder 5 through valve 1 to the common gas line, and from there - in parallel through all other valves to the atmosphere. Purging is carried out until the number of pulses received by 1x from the output of the generator 10 to the seventh input of unit 1 reaches N

my gas mixture, and before supplying each gas to the inlet of the gas analyzer, the gas is purged with a common gas line, and during the supply, the instantaneous values of the signal at the gas analyzer output are measured and stored. The signal from the zero gas is fixed until its steady value is determined, and the instantaneous values of the signal from the reference and attestable mixtures are measured and stored until a predetermined number of these values are typed.

After the signal from the certified gas mixture is recorded in each cycle, the concentration of the component in this mixture is calculated (based on the measurement results of the instantaneous values of the signals when they increase from the reference and from the certified gas mixtures), and then the reliability of the results obtained in the JM cycle is determined at certification i gas mixture If the certification results can be trusted, they are communicated to the operator, and the device proceeds to the certification of the (1 + 1) -th gas mixture, otherwise the (i + 1) -th certification cycle of the i-th gas mixture is performed. The operation of the device continues until the certification of the last gas mixture is completed.

The following data is stored in the memory 14: N is the total gas line purging time in units of the number of pulses, N is the number of measurements in a series of signal values from the zero gas, is the standard deviation threshold (RMS) of measurements on zero gas, N is the number measurements of the instantaneous values of the signal from the reference and from the certified gas mixtures, P and i, respectively, the threshold of the confidence probability and the threshold of the confidence interval of certification, Cf is the concentration of the analyzed component in the reference gas mixture, and also store standard values audio Student criterion used for different values of P (as a table), the operator can change the data by supplying to

output device 1b to the first input of the memory 14.

The operation of the device begins by the operator by filing with the first output of the device 18 to the first input of block 13 of the initial start code. After receiving this code, unit 13 purges the common gas line with zero gas. To do this, from the seventh output of block 13 to the input of generator 10 a start signal is given, and the eighth output of block 13 is given a code to the input of block 12. At the same time, from the output of generator 10 to the seventh input of block 13 pulses start to flow, and at the outputs of block 12 designed To match the signal level of the unit 13 with the valve supply voltage, a voltage combination appears that provides a common gas purge with zero gas. The voltage is applied to the first input of valve 1 and to the second inputs of the other valves, while zero minutes pro- gas goes from the tank 5 through the valve 1 in a common gas line, and from it - in parallel through all other valves to the atmosphere. Purging is carried out until the number of pulses coming 1x from the output of the generator 10 to the seventh input of unit 1 reaches N,

After that, the supply of zero gas to the input of the gas analyzer 9 and the recording of the gas analyzer output signal begin. Upon receipt of the No-th pulse from the output of the generator 10 to the seventh input of block 13, the last trans

supplies the input of block 12 with a code as a result of which from its outputs the first inputs of valves 1 and 4 receive the supply voltage, and all the other 5 inputs of the valves are de-energized. At the same time, zero gas from cylinder 5 through valve 1, common gas line, valve 4 and regulator 8 is fed to the inlet of gas analyzer 9. At the same time, the sixth output of unit 13 generates a pulse to the first input of ADC 11, which starts it. At the same time, the output signal of the gas analyzer 9, which enters the second input of the ADC 11, is converted into a digital code by it, and after the conversion is completed, the readiness pulse from the first output of the ADC 1J is sent to the sixth input of the block 13, which, the latter produces

0

five

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code at the fifth output of the fifth input

Upon expiration of the N purge time (on the time scale specified by generator 10), the reference gas mixture is fed to the gas analyzer input 9 and the instantaneous values of the gas analyzer output signal from the reference gas mixture are recorded when this signal increases. When from generator 10, block 13 again starts this, the same operations occur for ADC 11 and, having received a pulse ready, as in the similar operation from scratch, transmits the code on the fifth input to the gas. The only difference is that the memory 14 for storing the second instantaneous voltage from the outputs of the block 12 supplies the value of the gas output signal to the first inputs of valves 2 and 4, the analyzer 9 in the second memory cell 15 and fixing the output signal of the GAS 14 Having received this code, the memory unit 14 receives a digital code arriving at its sixth input from the second output of the A / D converter 11, and stores it in the first cell allocated for storing the instantaneous values of the signal from zero gas. When the next pulse arrives

Memory 14 and so on until N fixes on zero gas.

A determination is then made of the steady-state value of the signal from the zero gas. After supplying the code, the signal from the fourth output of block 13 to the first input of block 15 is sent to the first input of memory 14 for storing N, -ro measurement, as a result of which the latter starts up and calculates the average value of Ug, measurements on zero gas and CKOS g, of these measurements (data come from the fourth output of memory 14 to the second input of unit 15). After completing the calculation, block 15 transmits the value Up, on the second output to the fourth input of the memory 14, where it is stored, and then checks the fulfillment of the condition

0, - .. (1)

If this condition is met, the steady-state value of the signal from the zero gas is determined (it is equal to b,), and the system begins to purge the common gas line with a reference gas mixture. Otherwise, unit 15 generates, on the first output to the fourth input of unit 13, a code that results in the arrival of a pulse from the generator 10 to the seventh input of the unit. 13 begins recording a new series of N values, and

Memory 14, are implementations of the pn process flowing in the separate channel, the transmission f

W (P)

St, p + 1) (m., P + 1) -... (t,

the mean value of the new series of measurements to zero of the high is again determined, can be written in the form of fresh gas, standard deviation and so on until then.

 . 4, condition (1) is not fulfilled.

Purging the common gas line with a reference gas mixture is performed in the same way as a zero gas purge. gg The difference is that the voltage from the outputs of unit 12 is applied to the first input of valve 2 and to the second inputs of all other valves.

transmission coefficient and body channel;

where g

T T 1 g

... T | - constant time, s.

The process of increasing the signal during the gas analyzer 9 at zero

analyzer 9 is made until memory N 14 measures Up (K 1,2,3, ..., Nj) the instantaneous values of the signal from the reference

gas mixture in the process of increasing this signal from the level and ,,, to the steady state.

After this, the common gas line is secondly purged with a zero gas, fed to the input of the gas analyzer 9, recording a series of N, measuring the output signal of the gas analyzer and determining the steady-state value of this

signal until this value Ug is memorized in memory 14 (if the condition is met (1). The operation does not differ from the indicated one. Then the common gas line is purged with a certified gas mixture, supplied to the gas analyzer input 9 and fixing N measurements and (K 1,2,3 ,, .., Lр instantaneous values of the signal from the gas mixture being certified in the process of increasing this signal from the level Ug to the steady-state level. In this case, the sequence of operation is the same as reference gas mixture.

Measurements U .., and U, recorded in

Memory 14, are implementations of the transient process flowing in the measuring channel, the transfer function

 About the mountain can be written in the form.

W (P)

St, p + 1) (m., P + 1) -... (t, p + 0

orogo can be written as.

 four; (2)

transmission coefficient of the measuring channel;

where g

T T 1 g

... T | - constant time, s.

The process of increasing the signal at the output of the gas analyzer 9 at zero

71354074

initial conditions (which occurs when the input or reference gas mixture after the zero gas is supplied to the input) can be described by the function

U (t) f (T ,, T, ..., Tjt). C + and where U (t)

(3)

f (t ,, ti, ..

voltage at the outlet of the gas analyzer;

C is the concentration of the analyzed component of the gas mixture;

UQ is the voltage at the outlet of the gas analyzer at C 0; , T (t) is a function of time, depending on the constants T,, Tj, ..., T |, for example, when it has the form

f (T., T ,, t) -Ml: fliMliA (4)

i 4 1 2

Thus, for measurements and „can be recorded

where t, .t, ... , t, are the time points of measurement fixation, measured from the moment of supplying the gas mixture to the input of the gas analyzer 9.

For U measurements,

id, (t ,,,, t,). 2C, -; + and;

Ui, f (T ,, TjT.t) -t- U ,;

 (T, T, ..., T ,, t,). e Cij "- Uo,

where Cj is the concentration of the analyzed component in the i-th gas mixture, estimated in the J-M certification cycle. Transferring UQ and UQ to the left

parts of equations (5) and (6) and dividing

(6) to (5), you can get

 (Up, -Uo,);

U r-Uo2. -r (,);

 Oog §

(UpM, - and „)

By solving the system of equations (7) with the method of least squares, the rela

10 unknown relation

is

 R

Ni

K.1

(UAK- UOZ) (UPK-Uo,)

,(eight)

15

.(9)

(four)

„

(five)

20

After filing the code on the fifth input of the memory unit 14 to store the last measurement of the instantaneous value of the signal from the gas mixture to be certified, the unit 13 sends a signal from the third output

25 to the first input of block 16. With this signal, the last one starts and calculates an estimate of the concentration C optimal by the least squares method: according to formula (9) and the average

30 quadratic error of individual measurement b. The data (U,

and

lx

and

rk

0

, UQ., J Cf) Received by the required

oot (6)

new

willow

7)

the second output of memory 14 to the second input of block 16. Values of C; - and b are transmitted

35 from the second output of block 16 to the third output of memory 14, in which they are memorized.

At the end of the work of block 16 at its first exit to the third entrance

40 of block 13, a code is sent, as a result of which the latter puts into operation block 1.7, sending a signal from its second output to its first input. When block 17 is running, the criterion is determined

45 Student's data stored in memory 14; the mean square error of the individual measurement, the threshold of the confidence interval D, the number of measurements N ,. Then, the outcome of a given

50 threshold confidence probability, P, is the standard value of the student's criterion (according to the table stored in memory 14). In this case, all data comes from the second output of memory 14 to

55 the second input of block 17. The standard and the determined (calculated) values of the student's criterion are compared in magnitude. If standard.e more, the results of this certification cycle

are canceled, and a code is sent from the first output & 17 to the second input of block 13, according to which the latter starts the next certification cycle of the same gas mixture (as indicated). If the student's criterion value is greater than or equal to the standard one, from the first output of block 17 to the second input of block 13 a code is sent, according to which the latter turns on device 18, sends a signal from the first output to its first input. The device 18 receives the code C from the second input; from the first output of the memory 14 and prints the value C to the certificate for the gas mixture ;: expressed in units of concentration. Thereafter, from the first output of the device 19, the code is transmitted to the first input of 20 pulses, the analog-digital converter, the control unit, the setpoint determination unit, the concentration calculation unit, the measurement validation unit and the input / output device, all electrically controlled valves being three-way their third gas channels are connected to the atmosphere, and the second electrical inputs are connected to the outputs of the valve switching unit, the input of which is connected to the eighth output of the control unit, the sixth seventh inputs and outputs of which are respectively connected to the first output and input of the analog-digital converter and to the exit and entry

unit 13, as a result of which the latter produces the first certification cycle (1 + 1) -th gas mixture or stops the operation of the system if all n gas mixtures are certified.25

Thus, the invention makes it possible to increase the measurement performance while increasing the accuracy and level of automation.

Claims (2)

Invention Formula 1, Method of measuring the concentration of components of gas mixtures, including alternating supply of a zero gas analyzer, a reference gas mixture, a zero gas and the gas mixture being analyzed to the input, recording the gas analyzer output signals and determining the concentration by the magnitude of the signals, moreover, recording the output signal from zero gas carried out in a steady-state process, characterized in that, in order to increase the measurement performance, instantaneous values of output values are recorded at equal intervals of time ignalov by reference and analyzed mixtures only in the process of their growth. 2. A device for measuring the concentration of components of gas mixtures, containing a cylinder with zero gas, a cylinder with a reference gas mixture, cylinders with analyzed gas thirty 35 40 45 50 pulse generator, and the first, second, third and fourth inputs and outputs are connected to the first outputs and inputs, respectively, of an I / O device, a measurement accuracy determination unit, a concentration calculation unit and a set value determination unit, the second inputs and outputs of which are connected respectively to the first and the second, third and fourth outputs and inputs of the storage device, the fifth input and output of which are connected to the fifth output and input of the control unit, the sixth input is connected to the second output analog th-digital converter, the second input of which is connected to the output elektrichesko1chu analyzer. VSHZH1I Order 5686/38 Circulation 776 Shuffle pr-tie, Uzhgorod, st. Project, 4 mixtures, electrically controlled valves installed on the gas supply lines from the cylinders to the common gas pipeline j whose first electrical inputs are connected to the outputs of the valve switching unit, the flow regulator whose output is connected by a gas line to the gas analyzer inlet, .and memory device, which is based on the fact that, in order to increase productivity, accuracy and level of automation of measurements, electrical controllers are introduced into it My valve, the first input of which is connected to the output of the valve switching unit, installed between the output of the common gas line and the input of the flow regulator, the generator 0 five 0 pulse generator, and the first, second, third and fourth inputs and outputs are connected to the first outputs and inputs, respectively, of an I / O device, a measurement accuracy determination unit, a concentration calculation unit and a set value determination unit, the second inputs and outputs of which are connected respectively to the first and the second, third and fourth outputs and inputs of the storage device, the fifth input and output of which are connected to the fifth output and input of the control unit, the sixth input is connected to the second output analog th-digital converter, the second input of which is connected to the output elektrichesko1chu analyzer. Subscription