RU2411511C1 - Device for monitoring concentration of dangerous gases - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: device for controlling concentration of dangerous gases has CH₄ 1, carbon monoxide CO 2 and oxygen O₂ 3 sensors, a signal amplifier 4, an analogue switch 5, an analogue-to-digital converter 6, a microcomputer 7, memory 8, data display 9, an alarm device 10, an interface device 11 with a personal computer, a control device, a clock 13, a power supply 14, a first 15, second 16 and third 17 relay, a multivibrator 18 and a transmitter 20, having a driving generator 21, a modulating code generator 22, a phase shift keying device 23, a transmitting key 24, a power amplifier 25 and a transmitting antenna 26. The control point has a receiving antenna, a high frequency amplifier, an adjustment unit, a heterodyne, a mixer, an intermediate frequency amplifier, a signal detector (selector) first and second spectrum analysers, a phase doubler, a comparator unit, a threshold unit, a delay line, a switch, an alarm sounder, a phase halver, a narrow-band filter, a phase detector and a recording unit.

EFFECT: possibility of timely adoption of timely measures which enable to lower gas pollution of residential, public and production facilities through transmission of alarm information to a gas security service if concentration of methane CH₄ and carbon monoxide CO exceed a certain maximum permissible concentration value or if concentration of oxygen O₂ becomes lower than a permissible value.

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Description

The proposed device relates to atmospheric control and is intended for environmental monitoring, in particular for automatic continuous monitoring of the concentration of combustible gases (methane - CH ₄ , oxygen O ₂ and carbon monoxide - CO) in residential, communal and industrial premises in order to detect excess concentration and timely adoption of effective measures to reduce gas pollution.

Known devices for controlling the concentration of hazardous gases (USSR author's certificate No. 1500797, 1744625; RF patents No. 20133565, 2096776, 2131601, 2161785, 2171468, 2199113, 2209419, 2253108; US patents No. 4028057, 4476096, 5798945, 6229449, 66004244, 66004244 , 6856253, 6940410; German patent No. 4412447; Japanese patents No. 3442242, 3700379; Karpov E.F. et al. "Author's gas protection and control of the mine atmosphere. - M .: Nedra, 1984, pp. 101-109 and others )

Of the known devices closest to the proposed is a "Device for monitoring the concentration of hazardous gases" (RF patent No. 2253108, G01N 27/12, 2004), which is selected as a prototype.

The specified device contains three independent sensors that react selectively to a specific gas: methane - CH ₄ , carbon monoxide - CO, oxygen - O ₂ , a microcomputer, a clock and an interface device with a personal computer. Information taken from sensors is converted into a digital code and transmitted to a computer display. The device has a time counter, information storage in a common database and comparisons with maximum permissible concentrations.

However, this device does not provide remote monitoring of hazardous gas concentrations and the transmission of alarm information to the gas safety service if the set maximum permissible concentration (MPC) value for CH ₄ and CO is exceeded or the content decreases below the limit value for oxygen O ₂ , which leads to untimely adoption of measures to reduce gas contamination.

An object of the invention is the timely adoption of effective measures to reduce gas contamination in residential, communal and industrial premises by transmitting alarm information to the gas safety service in case there is an excess of the set MPC for CH ₄ and CO or a decrease in the content of the limit value for O ₂ .

The problem is solved in that a device for monitoring the concentration of hazardous gases, containing, in accordance with the closest analogue, methane, carbon monoxide and oxygen sensors, a signal amplifier, analog switch, analog-to-digital converter, microcomputer, storage device, information board, alarm device alarms, an interface device with a personal computer, a control device, a clock and a power supply, each sensor being made in the form of a semiconductor gas sensor and by connected signal amplifier, analog switch and analog-to-digital converter is connected to a microcomputer, the outputs of which are connected respectively to the inputs of the storage device, information board, alarm device, interface device with a personal computer and control device, the outputs of the control device are connected respectively to the inputs of the analog switch and analog-to-digital converter, and the output of the clock is connected to the input of the microcomputer, differs from the nearest analog in that it is equipped with three relays, a multivibrator, a transmitter and a remote monitoring point, the relay windings being connected to the corresponding outputs of the microcomputer, the transmitter is made in the form of series-connected master oscillator, phase manipulator, the second input of which is connected to the output of the modulating code generator, telegraph key , power amplifier and transmitting antenna, transmitter and multivibrator through the make contact of the first relay are connected to the power supply, the make contact of the second relay is turned on Incidentally, with a resistor in one of the arms of the multivibrator, the closing contacts of the third relay and the multivibrator relay are connected in parallel with the telegraph key of the transmitter, the remote control point is made in the form of a receiving antenna, a high-frequency amplifier, a mixer, the second input of which is connected through the local oscillator to the output of the tuning unit, an intermediate frequency amplifier, a phase doubler, a second spectrum analyzer, a comparison unit, the second input of which is connected to the output through the first spectrum analyzer ohm of an intermediate frequency amplifier, a threshold unit, the second input of which is connected to its output via a delay line, a key, the second input of which is connected to the output of an intermediate frequency amplifier, phase detector and registration unit, a phase divider into two and a narrow-band filter are connected in series to the output of the phase doubler , the output of which is connected to the second input of the phase detector, an audible warning device and a tuning block are connected to the output of the threshold block.

The structural diagram of a device for monitoring the concentration of hazardous gases is presented in figure 1. The structural diagram of the remote control point is shown in figure 2.

A device for monitoring the concentration of hazardous gases contains methane sensors CH ₄ 1, carbon monoxide CO 2 and oxygen O ₂ 3, each of which is made in the form of a semiconductor gas sensor and through a series-connected signal amplifier 4, an analog switch 5 and an analog-to-digital converter 6 are connected with a microcomputer 7, the outputs of which are connected respectively to the input of the storage device 8, information board 9, device 10 alarm, interface device 11 with a personal computer IBM-PC and devices and 12 controls, the outputs of which are connected respectively to the input of the analog switch 5 and the analog-to-digital converter 6, a power supply unit 14, to the outputs of which an amplifier 4 of signals is connected, an analog switch 5, a microcomputer 7, an interface device 11 with a personal computer, a control unit 12 and clock 13, the output of which is connected to the microcomputer 7, the relay windings 15, 16, and 17 connected to the corresponding outputs of the microcomputer 7, the multivibrator 18 and the transmitter 20, which is made in the form of series-connected master oscillator 21, phase m a nippulator 23, the second input of which is connected to the output of the modulating code generator 22, the telegraph key 24, the power amplifier 25 and the transmitting antenna 26. In this case, the transmitter 20 and the multivibrator 18 are connected to the power supply unit 14 containing the mains adapter via a make contact 15.1 of the first relay backup battery and charger. The make contact 16.1 of the second relay is connected in series with the resistor 27 to one of the arms of the multivibrator 18. The make contacts 17.1 and 19.1 of the third relay and the multivibrator relay are connected in parallel with the telegraph key 24 of the transmitter 20.

The remote control point is located in the gas safety service and is made in the form of a series-connected receiving antenna 27, a high-frequency amplifier 28, a mixer 31, the second input of which is connected through the local oscillator 30 to the output of the tuning block 29, an intermediate frequency amplifier 32, a phase doubler 35, and a second analyzer 36 of the spectrum, comparison unit 37, the second input of which is connected through the first spectrum analyzer 34 to the output of the intermediate frequency amplifier 32 of the threshold unit 38, the second input of which is connected to the delay line 39 with the output, a key 40, the second input of which is connected to the output of the intermediate frequency amplifier 32, a phase detector 44 and a recording unit 45, connected in series to the output of the phase doubler 35 of the phase divider 42 and the narrow-band filter 43, the output of which is connected to the second input of the phase detector 44. The control input of the tuning unit 29 and the input of the audio signaling device 41 are connected to the output of the threshold unit 38.

Spectrum analyzers 34 and 36, a phase doubler 35, a comparison unit 37, a threshold unit 38, and delay lines 39 form a detector (selector) 33 of complex phase shift keyed signals (QPSK).

The device operates as follows.

After turning on the supply voltage, the microcomputer 7 is started. Through the microcomputer control device 12, according to the program introduced into it, it sequentially starts the measurement cycles from three sensors 1, 2, and 3. Measuring information from the outputs of the methane sensors CP ₄ 1, carbon monoxide CO 2 and oxygen O ₂ 3 through an amplifier 4 signals and an analog switch 5 is fed to the input of an analog-to-digital converter 6. The converted digital code is sent to the microcomputer 7, which compares its value in the microcomputer 7 with the maximum allowable. When the logging mode is activated after certain periods of time, the measured values with a time stamp from 13 hours are recorded in the storage device 8.

The device employs semiconductor gas detectors that measure in a wide concentration range, which makes it possible to use the device not only as a threshold alarm device, but also to receive measured values at any time on the information board 9 or to send measurement information to the interface device 11 with a personal computer (PC). The use of microcomputer 7 allows the processing of measurement information, switch to continuous measurement mode and output information to the analog switch 5, record the measurement results in memory 8 according to the programs specified in the microcomputer 7, as well as in case of emergency.

The use of a storage device 8 and a real-time clock 13 make it possible to record the values of the measured parameters at specified intervals, which provides a detailed analysis of the causes of the accident. The use of semiconductor gas sensors allows measurements to be made in a wide range of ambient temperatures and humidity with the same error, which does not require temperature compensation of a block of physical sensors and amplifiers. The ability to measure the concentration parameters of methane and oxygen allows us to analyze the ratio of their concentrations and warn about the formation of explosive methane and oxygen in concentrations close to the ratio 1: 2 (CH ₄ : O ₂ ).

The device contains an alarm block 10, the operation of which occurs in the following cases:

- excess of maximum permissible concentrations (MPC) for CH ₄ and CO in a controlled room;

- reduction below the established limit of the concentration of O ₂ .

After the alarm is triggered, the device constantly monitors all monitored parameters and switches to the mode of constant information transfer to the PC.

In the event that an excess of the set MPC for methane CH ₄ occurs, the microcomputer 7 includes an alarm and switches to the logging and direct transmission of information to the interface device 11 with a personal computer. Request for a measurement protocol is possible from a personal computer at any time.

At the same time, a constant voltage from the corresponding output of microEMV 7 is supplied to the first relay 15. The latter is activated and closes contact 15.1, through which power from the power supply unit 14 is supplied to the multivibrator 18 and transmitter 20.

After the transmitter 20 is turned on by the master oscillator 21, a high-frequency oscillation is generated

u _c (t) = U _c Cos (w _c t + φ _c ), 0≤t≤T _s ,

where U _c , w _c , φ _c , T _c - amplitude, carrier frequency, initial phase and duration of high-frequency oscillations,

which is fed to the first input of the phase manipulator 23. At the second input of the last, a modulating code M (t) is supplied from the output of the modulating code generator 22. The modulating code M (t) is the identification number of the room, building, where the hazardous gas leak occurred. As a result of phase manipulation, the output of the phase manipulator 23 produces a complex signal with phase manipulation (PSK).

u ₁ (t) = U _c · Cos [w _c t + φ _k (t) + φ _s ], 0≤t≤T _s ,

where φ _к (t) = {0, π} is the manipulated component of the phase, which displays the law of phase manipulation in accordance with the modulating code M (t), and φ _к (t) is const at Кτ _э <t <(к + 1) τ _e and can change abruptly at t = Kτ _e , i.e. at the borders between elementary premises (K = 1, 2, ..., N-1);

τ _e , N is the duration and number of chips that make up the signal of duration T _c (T _c = τ _e · N).

The generated signal QPSK signal u ₁ (t) through the telegraph key 24 and the power amplifier 25 enters the antenna 26, is radiated by it, is controlled by the receiving antenna 27 of the control point and through the high-frequency amplifier 28 is fed to the first input of the mixer 31, to the second input whose voltage is applied to the local oscillator 30 of a ramp frequency

u _g (t) = U _c Cos (w _g t + πrt ² + φ _g ), 0≤t≤T _p ,

- скорость изменения частоты гетеродина 30.Where

- the rate of change of the frequency of the local oscillator 30.

It should be noted that the search for PSK signals in a given frequency range Df is carried out using the tuning block 29, which periodically with a period Тп linearly changes the frequency W _{g of the} local oscillator 30. A sawtooth voltage generator can be used as the tuning block 29.

At the output of the mixer 31, voltages of combination frequencies are generated. The amplifier 32 is allocated an intermediate frequency voltage

u _pr (t) = U _pr · Cos [w _pr t + φ _к (t) -πrt ² + φ _pr1 ], 0≤t≤T _c ,

;Where

;

w _CR = w _with -w _g - intermediate frequency;

φ _CR = φ _s -φ _g ,

which is a complex signal with a combined phase of manipulation and linear frequency modulation (QPSK-LFM) at an intermediate frequency W _pr and fed to the input of the detector (selector) of the QPSK signal, consisting of a phase doubler 35, analyzers 34 and 36 spectra, block 37 comparison threshold block 38 and delay line 39.

A harmonic voltage is generated at the output of the phase doubler 35

u ₂ (t) = U ₂ · Cos [2w _pr t-2πrt ² + 2φ _pr ], 0≤t≤T _s ,

.Where

.

As a phase doubler 35, a multiplier can be used, on the two inputs of which the same signal u _pr (t) is supplied.

Since 2φ _k (t) = {0.2π}, phase manipulation is already absent in the indicated voltage.

The width of the spectrum Δf _{2 of the} second harmonic is determined by the duration T _{s of the} signal (Δf ₂ = 1 / T _s ), while the width of the spectrum Δf _{c of the} input QPSK signal is determined by the duration τ _{e of} its elementary premises (Δf _c = 1 / τ _e ), t. e. the width of the spectrum Δf _{2 of the} second harmonic of the signal in N paz is less than the width of the spectrum Δf _{c of the} input QPSK signal (Δf _c / Δf ₂ = N).

Therefore, when the phase of the QPSK signal is doubled, its spectrum “folds” N times. This circumstance makes it possible to detect and select the QPSK signal among other signals (interference) and noise even when its power at the receiver input is less than the power of noise and interference.

The width of the spectrum Δf _{c of the} input QPSK signal is measured using a spectrum analyzer 34, and the spectrum width Δf _{2 of the} second harmonic of the signal is measured using a spectrum analyzer 36. The voltage U _I and U _II , proportional to Δf _c and Δf _2, respectively, from the outputs of the analyzers 34 and 36 is supplied to the two inputs of the comparison unit 37. Since U _I U U _II , a positive voltage is generated at the output of the comparison unit 37, which exceeds the threshold voltage U _then in the threshold block 38. The threshold voltage U _then is selected so that it is not exceeded by random noise and noise. When the threshold level U _pores is exceeded, a constant voltage is generated in the threshold block 38, which is supplied to the control input of the key 40, opening it to the input of the delay line 39, to the control input of the tuning unit 29, turning it off, and to the input of the sound signaling device 41. Key 40 in the initial state is always closed.

When the tuning of the local oscillator 30 ceases, the following voltage is allocated by the intermediate frequency amplifier 32

u _pr1 (t) = U _pr · Cos [w _pr t + φ _k (t) + φ _pr ], 0≤t≤T _s ,

which through the public key 40 enters the first (information) input of the phase detector 44.

At the output of the divider 42 phases into two, in this case, a harmonic voltage is formed

u ₃ (t) = U ₃ · Cos (w _{pr pr} t + φ) 0≤t≤T _s,

which is allocated by the narrow-band filter 43, is used as a reference voltage and is supplied to the second (reference) input of the phase detector 44. At the output of the latter, a low-frequency voltage is allocated

u _n (t) = U _n · Cosφ _k (t), 0≤t≤T _c ,

;Where

;

proportional to the modulating code M (t). This voltage is detected by the registration unit 45. This voltage contains digital data on the place and time of leakage of hazardous gases.

To increase the reliability of reception and registration of a complex QPSK signal, the latter is duplicated several times with an interval, for example, of 20 seconds. This is ensured by the operation of the multivibrator 18 in unbalanced mode. Contact 19.1 of the relay 19 of the multivibrator 18 periodically at regular intervals, for example 20 seconds, closes the circuit of the telegraph key 24 of the transmitter 20, which sends the FMK signal to the space after the same time interval. At the same time, the sound signaling device 41 gives sound signals with an interval of 20 seconds, which indicates a methane CH ₄ leak with the heading “DANGER”.

The delay time τ _{s of} line 39 is delayed so that it is possible to repeatedly receive and fix the PSK signal at a certain frequency. The carrier frequency is also an identification feature. Transmitters installed in various rooms and tasks have their own carrier frequencies in a given frequency range Df. Periodic viewing of a given frequency range Дf provides detection of the carrier frequencies of transmitters installed in rooms where dangerous gases have leaked.

After the time τ _{s, the} voltage from the output of the delay line 39 is supplied to the reset input of the threshold block 38 and resets its contents to zero. At the same time, the sound signaling device 41 stops its operation, the key 40 is closed, and the tuning unit 29 is turned on, i.e. they are transferred to their original state. The device is ready for further work.

When the next QPSK signal is detected on a different carrier frequency, the device operates in a similar manner.

If there is an excess of the MPC value for methane CH ₄ and carbon monoxide CO, then constant voltages are applied to the first 15 and second 16 relays that operate. Contact 16.1 of the second relay closes, and includes a resistor 27 in the circuit of the multivibrator 18, and puts its work in symmetrical mode. The relay 19 of the multivibrator 18 is activated at regular intervals of time, for example, 5 seconds, and its contact 19.1 closes the circuit of the telegraph key 24 of the transmitter 20 after the same time interval of 5 seconds. This corresponds to a VERY DANGEROUS gas leak rate.

In case there is an excess of the established MPC for CH ₄ and carbon monoxide CO and a decrease in the content below the limit for oxygen O ₂ , i.e. If an explosive mixture of methane and oxygen is formed in concentrations close to the 1: 2 ratio (CH ₄ : O ₂ ), then all three relays 15, 16 and 17 are activated. Contact 17.1 of the third relay closes the circuit of the telegraph key 24 of the transmitter 20 short. At the same time, the transmitter 20 sends a continuous QPSK signal of considerable duration into space, and the sound signaling device 41 reproduces a continuous sound signal, characterizing the situation as “extremely dangerous”.

The device can operate in the following modes:

1. The duty officer, in which there is a continuous measurement of the values of the monitored parameters and comparison with threshold values of MPC.

2. Logging mode. At specified intervals, the measured value of the monitored parameters is recorded in the non-volatile memory of the device.

3. The mode of reading information. Information is transferred from the storage device to the computer interface.

4. Emergency mode. In emergency mode, when the MPC is exceeded, an alarm is triggered and the device enters the remote transmission of alarm information to a control point located in the gas safety service.

The power supply unit of the device contains a backup battery, which allows you to power the device for a long time when you turn off the external power.

Calibration of the device is carried out in the control base camera.

The proposed device can be implemented industrially on the basis of known elements and blocks, on commercially available components, such as semiconductor gas sensors manufactured by Avangard - Microsensor CJSC.

Thus, the proposed device in comparison with the prototype allows you to take effective measures in a timely manner that reduce gas contamination in residential, communal and industrial premises. This is achieved by transmitting alarming information in cases where there is an excess of the set MPC for methane CH ₄ and carbon monoxide CO or a decrease in the content below the limit value for oxygen O ₂ .

Claims (1)

A device for monitoring the concentration of hazardous gases containing methane, carbon monoxide and oxygen sensors, a signal amplifier, an analog switch, an analog-to-digital converter, a microcomputer, a storage device, an information board, an alarm device, an interface device with a personal computer, a control device, a clock and a power supply, each sensor is made in the form of a semiconductor gas sensor and through a series-connected signal amplifier, an analog switch and an A / D converter is connected to a microcomputer, the outputs of which are connected respectively to the inputs of a storage device, an information board, an alarm device, an interface device with a personal computer and a control device, the outputs of the control device are connected respectively to the inputs of an analog switch and an analog-to-digital converter, and the output hours connected to the input of the microcomputer, characterized in that it is equipped with three relays, a multivibrator, a transmitter and a remote role, and the relay windings are connected to the corresponding outputs of the microcomputer, the transmitter is made in the form of serially connected master oscillator, phase manipulator, the second input of which is connected to the output of the modulating code generator, telegraph key, power amplifier and transmitting antenna, the transmitter and multivibrator through the make contact of the first relay connected to the power supply, the make contact of the second relay is connected in series with the resistor to one of the arms of the multivibrator, the make contacts of the third relay and p the multivibrator is connected in parallel with the telegraph key of the transmitter, the remote control point is made in the form of a series-connected receiving antenna, high-frequency amplifier, mixer, the second input of which is connected through the local oscillator to the output of the tuning unit, intermediate frequency amplifier, phase doubler, second spectrum analyzer, comparison unit, the second input of which, through the first spectrum analyzer, is connected to the output of the intermediate frequency amplifier, a threshold block, the second input of which is through the delay line connected to its output, a key, the second input of which is connected to the output of the intermediate frequency amplifier, phase detector and registration unit, a phase divider into two and a narrow-band filter, the output of which is connected to the second input of the phase detector, is connected to the output of the threshold block to the output of the phase doubler an audible warning device and a tuning block are connected.

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