RU1334923C - Gas analyzer - Google Patents

Abstract

The invention relates to the field of analytical instrumentation and can be used to control emissions of industrial enterprises and vehicles into the atmosphere. The purpose of the invention is to increase sensitivity. The essence of the invention is that it automatically monitors the maximum value of the output useful signal. The useful signal from the output of the first synchronous detector 8 is additionally detected by the second} synchronous detector, to the control input of which a signal from the output of the generator, whose frequency is less than useful signal modulation frequencies by a mirror modulator. From the output of the siphon detector, the signal enters one of the inputs of the summing device, the other input of which receives the signal from the output of the generator. At HanvfAW, at the output of the summing device, a signal other than zero, the U-shaped holder moves along the notches of the mirror module with the motor until until the signal at the gate of the summing device is equal to zero. Thus, in the gas analysis, the maximum of the measured signal is maintained, which makes it possible to expand the measurement range to the defense of small k (t | centers of the analyte 1 t

Description

The invention relates to the field of analytical instrumentation and can be used to control emissions of industrial enterprises and vehicles into the atmosphere, as well as in a number of technological processes associated with the formation of gases.

The purpose of the invention is to increase sensitivity.

The drawing shows a structural diagram of a gas analyzer ..

The gas analyzer contains an optical unit 1, which includes a radiation source, a working and reference cuvette, a focusing system, and an optical filter, a mirror modulator 2 with recesses, a synchronization pulse shaper, containing a U-shaped holder 3 with an optocouple placed from it (on not shown), located opposite the cutouts in the mirror modulator, 2, radiation receiver 4, pre-amplifier 5, synchronous filter b, main amplifier 7, first synchronous detector 8, recording device 9, control driver signal 10, the generator And, the second synchronous detector 12, the adder 13 and the motor 14.

The gas analyzer operates as follows.

The radiation from the source located in the optical unit 1 is divided into two streams that pass through the working and reference cuvettes, are modulated by a mirror modulator 2 and sent to the receiving platform of the radiation receiver 4, in which it is converted into an electrical signal. This alternating electrical signal, after amplification by the preamplifier 5, enters the non-input of the synchromic filter G, in which it is filtered, and after additional amplification by the main amplifier 7, it is fed to the input of the first synchronous detector 8, which controls the voltage of CMiixpoHHOQ. rectification P8p (5-variable input signal with additional filtering. The constant output voltage of the first synchronous detector 8, riponoptical to the concentration of the test gas in the working cell, is controlled by the recording device 9. The control voltage for the synchronous filter 6 and the first synchronous detector 8 is the output voltage of the driver of the control signals 1–10; synchronized with the output pulses of the driver of the synchronizing pulse generator, an alternating voltage is generated by the generator 11, b / erodarl which

the motor 14 performs mechanical scanning of the U-shaped holder along the notches of the mirror modulator 2, designed to generate synchronizing pulses, thereby changing

phase difference between modulated

input signal and control voltage. This leads to a synchronous frequency

at the input voltage of the generator 11, a slight change in the level of the detected useful signal at the output of the device (the amplitude of fluctuations in the level of the detected useful signal at the output of the device is established by changing the amplitude of the output voltage of the generator 11 and is selected from the condition for obtaining the minimum error introduced into the measurement).

If at the middle position of the U-shaped holder a useful output signal

the device is maximum, which indicates the coincidence of the phases of the measured and control signals, then any scan of the G1-shaped holder along the cutouts of the modulator only

this decreases, while the constant voltage level 1 at the output of the second synchronous detector 12 will be equal to zero, since the positive half-wave of the signal at the output of the device will be compensated by the negative half-wave (the control is the signal for the second synchronous detector 12 generator output voltage 11). Thus, the output of the summing device 13 is not

appears to be a constant component and the U-shaped holder does not move to change the phase difference between the measured " control signals. If in the middle position of the U-shaped

Since the useful output signal of the device is not maximum, scanning a U-shaped holder leads to a synchronous decrease and increase in the useful output signal of the device, so that the output of the second synchronous detector 12 exhibits a constant voltage, which is summed in the summing device 13c voltage of the generator 11 and

leads to the displacement of the U-shaped holder until a maximum signal is established at the output of the gas analyzer.

Thus, the gas analyzer automatically supports (the maximum of the measured output signal is increased, and consequently, its sensitivity is increased by a factor of two or more, that is, the measurement range expands towards small concentrations of the analyte.

(56) Copyright certificate of the USSR No. 849857, cl. G 01 N 21 / 61.1981.

Claims (1)

The claims A gas analyzer containing an optically coupled optical unit, a mirror modulator with cutouts for generating synchronizing pulses, ow, a radiation receiver, the output of which is 1 through a preamplifier, a synchronous | filter, a main amplifier and a first synchronous detector connected to the input of the recording device as well as a generator of synchronizing pulses, including a U-shaped holder mounted on it and located opposite the notches of the mirror modulator for forming a synchronizing pulse s optocoupler, made with the possibility of moving along the radius of rotation of the mirror modulator, the output of which is connected to the input USSR author's certificate No. 1246724, cl. G 01 N 21/61, 1984. a control signal booster, the output of which is connected to the control inputs of the synchronous filter and the first synchronous detector, and a motor mechanically coupled to the U-shaped holder of the synchronizing pulse shaper, characterized in that, in order to increase the sensitivity, it further comprises a second synchronous detector the input of which is connected to the output of the first synchronous detector, a generator and a summing device, the motor being connected to the output of the summing device, and the inputs of the summing device roystva coupled to the generator output and the second synchronous detector, the output of the generator is also coupled to a control input of the second synchronous detector. W Editor N. Timonina Compiled by A. Levy Techred M. Morgenthal Order 3333 Circulation NGO Search for Rospatent 113035, Moscow, Zh-35, Rauska nab., 4/5 Production and Publishing Plant Patent, Uzhgorod, 101 Gagarina St. Proofreader L. Pilipenko