RU2253108C1 - Device for controlling concentrations of dangerous gases - Google Patents

Abstract

FIELD: atmosphere control technologies.

SUBSTANCE: device has three independent sensors, reacting selectively on certain gas: methane - CH₄, carbon monoxide - CO, oxygen - O₂, microcomputer, clock and interface device with PC. Information taken from sensors is transformed to digital code and sent to computer display. Device includes time count, recording of data in unified base and comparison to maximally allowed concentrations of these substances.

EFFECT: broader functional capabilities, higher information yield.

1 dwg

Description

The invention relates to atmospheric control and is intended for environmental monitoring, in particular for continuous monitoring of the level of gas impurities (carbon monoxide - CO and methane - CH ₄ ) in the atmosphere of residential, industrial and other premises.

Known methane detector containing a bridge measuring circuit, the input of which is connected to the output of the voltage regulator, and the output of the bridge measuring circuit is connected to the input of the scaling amplifier, the output of the scaling amplifier is connected to the first input of the comparator for exceeding the threshold level of methane, the output of the comparator of the threshold level of methane is connected to the first input threshold level indicator, the source of the first reference voltage connected to the second input of the comparator for exceeding the threshold level, analog a level converter (ADC) connected to the output of the scaling amplifier and to the input of a digital indicator, a battery discharge comparator, the first input of which is connected to a source of the second reference voltage, and the output is connected to the second input of the threshold level indicator, the battery, the first, second, and third the outputs of which are connected respectively to the inputs of the converter and the voltage stabilizer and the second input of the battery discharge comparator [1].

The disadvantages of this device are:

- the operation of the device only in the threshold alarm mode and the inability to use it for the quantitative measurement of concentrations of a controlled parameter;

- the impossibility of recording emergency situations;

- control of only one parameter.

Closest to the technical nature of the claimed device is a methane detector containing a bridge measuring circuit, a DC amplifier, an analog-to-digital converter, an arithmetic-logic device, a storage device and a battery. The output of the digital-to-analog converter is connected to the output of a DC amplifier, the output of which is connected to the input of the bridge measurement circuit and the first input of the analog switch. The output of the analog switch is connected to the input of an analog-to-digital converter, the output of which is connected to the first input of the arithmetic-logic device, the first, second, third and fourth outputs of which are connected respectively to the input of the digital-to-analog converter, the threshold level indicator input, the fourth analog switch input and the memory input devices. The second input of the arithmetic-logic device is connected to the output of the storage device [2].

The disadvantages of this device are the difficulty of its maintenance due to the presence of a large number of adjustment elements and low measurement accuracy.

The objective of the invention is the provision of continuous monitoring of the level and ratio of gas impurities in a wide range.

The technical result is the expansion of the functionality of the device and increasing information content.

This is achieved by the fact that in a methane detector containing a measuring circuit including a methane sensor, a measuring information processing circuit including a signal amplifier, an analog switch, an analog-to-digital converter, as well as a storage device, an information board and a power supply, the measuring circuit further comprises a sensor carbon monoxide and an oxygen sensor, and the processing circuit of the measuring information is a microcomputer, a clock and an interface device with a PC, while the sensors of the measuring part are made in the form of gas gas sensors, the output of the analog-to-digital converter is connected to the input of the microcomputer, the outputs of the microcomputer are connected to the input of the storage device, to the input of the interface device from the PC, to the input of the control device and to the input of the information board, the outputs of the control device are respectively from the input of the analog switch and with the input of an analog-to-digital converter, and the output of the clock with the input of a microcomputer.

Indeed, semiconductor gas detectors are used in the device, which 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 the values of the measured parameters at any time or to send the measurement information to a personal computer (PC) . The use of microcomputers allows the processing of measurement information, switches to continuous measurement mode and displays information in an analog switch, captures the results of measurements in a storage device according to the programs specified in the microcomputer, as well as in case of emergency.

The use of a storage device and a real-time clock make it possible to record the values of the measured parameters at specified intervals, which allows 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 of 1: 2 (CH ₄ : O ₂ ).

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

- exceeding the maximum permissible level (MP) according to CH ₄ and CO in a controlled room;

- decrease 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.

The block diagram of the inventive device is illustrated in the drawing.

The device contains 1, 2, 3 — physical sensors of methane concentrations — CH ₄ , carbon monoxide — CO, oxygen — O ₂ , 4 — a signal amplifier, 5 — an analog switch, 6 — an analog-to-digital converter, 7 — a microcomputer, 8 — a memory device, 9 - information board for displaying current information, 10 - alarm device, 11 - interface device with an IBM-PC personal computer, 12 - signaling device control device, 13 - real-time clock, 14 - power supply unit containing a power adapter, a battery backup battery Charger.

The device operates as follows. After switching on the supply voltage, the microcomputer 7 is started. Through the control device 12, the microcomputer, according to the program introduced into it, sequentially starts the measurement cycles from three sensors. Measuring information from the outputs of sensors 1, 2, and 3 through a signal amplifier 4 is fed to the input of an analog switch 5, the output of which is fed to the input of an analog-to-digital converter 6. The converted digital code is sent to the microcomputer, which translates the values of the received code into the accepted units of measurement of the computer . Next, a comparison of its value in the microcomputer with the maximum permissible. When the logging mode is activated, at certain time intervals, the measured values with the time stamp from the clock are recorded in the storage device 8.

In the event that an excess of the set remote control value for CH ₄ and CO occurs or the content decreases below the limit value for O ₂ , the microcomputer activates an alarm and switches to the logging mode and direct transmission of information to a personal computer 11. A measurement protocol can be requested from a personal computer to any moment in time.

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 transmitted from the storage unit to the computer interface.

4. Emergency mode. In emergency mode, when the remote control is exceeded, an alarm is triggered and the device enters the mode of constant transmission of measured concentrations of monitored parameters.

5. Direct transmission of measurement results (terminal mode).

Terminal mode is enabled:

1. In case of exceeding the MAC.

2. In the case of a request for measurement information from a personal computer.

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.

After external power is supplied, the battery controller charges it.

Calibration of the device is carried out in the control gas chamber. The gas composition of the chamber is controlled by a laboratory gas chromatograph LHM-8MD.

The gas sensor of the device is placed in the gas chamber. Calibration is carried out in three concentrations: minimum (at the background level), maximum (at the level of the measurement limit) and average. Calibration is carried out by digital correction of the measuring information, by the method of recording calibration coefficients for each of the three determined gases in the microcomputer.

The claimed device is implemented industrially based on a microcontroller company ATMEL AT89C51; 14-bit ADC MAX 14061, analog switch K564KP1, hours DS 1208; Memory ADS12803; interface from a PC to commercially available components, such as semiconductor gas sensors manufactured by Avangard-Microsensor CJSC, the measuring circuit of the device is assembled. The housing contains two compartments, one leaky one with passive ventilation, with gas sensors, and the second tight one with an electronic circuit. The device is intended for operation in residential, industrial and other premises, therefore, twisted pair is selected as a channel for transmitting information to a PC. The main power source is an electric network with a voltage of 220 V. The autonomy of the device when powered by a battery does not exceed 10 days.

Sources of information

1. Karpov E.F., Birengerg I.E., Basovsky B.I. Automatic gas protection and control of the mine atmosphere. M .: Nedra, 1984, pp. 101-109.

2. Patent of the Russian Federation No. 2131601, MKI 6 G 01 N 27/16, 03.16.98.

Claims (1)

A device for monitoring hazardous gas concentrations, comprising a measuring circuit including a methane sensor, a measuring information processing circuit including a signal amplifier, an analog switch, an analog-to-digital converter, as well as a storage device, an information board and a power supply unit, characterized in that the measuring circuit is additionally contains a carbon monoxide sensor and an oxygen sensor, and a processing circuit for measuring information - a microcomputer, a clock and an interface device with a PC, while the sensors are measuring part are made in the form of semiconductor gas sensors, the output of the analog-to-digital converter is connected to the input of the microcomputer, the outputs of the microcomputer are respectively connected to the input of the storage device, to the input of the interface device from the PC, to the input of the control device and to the input of the information board, the outputs of the control device, respectively with the input of the analog switch and with the input of the analog-to-digital converter, and the output of the clock with the input of the microcomputer.