SU1528932A1 - Portable mine methane indicator - Google Patents

Abstract

The invention relates to instrumentation technology and can be used to monitor and signal the concentration and rate of its rise in methane in mines. The purpose of the invention is to improve the accuracy of the assessment of the degree of danger of the gas situation. The detector contains a methane sensor, threshold elements of the lower and upper levels of methane concentration, a memory unit, an alarm unit, a coincidence circuit, and pulse shapers. The goal is achieved by taking into account the rate of increase in concentration and the elimination of false alarms during bursts of methane concentrations of less than 2%. 3 il.

Description

The invention relates to instrumentation technology and can be used for the continuous automatic control of methane concentration and its rate of buildup in the atmosphere of coal mines, developing seams, dangerous by sudden ejections of coal and gas, as well as for signaling that the permissible concentration of methane and its velocity increase.

The aim of the invention is to improve the accuracy of the assessment of the degree of danger of the gas situation.

FIG. 1 shows the block diagram of the proposed detector; in fig. 2 — alarm unit of the portable methane detector; on |

FIG. 3 - timing diagrams explaining the operation of the detector.

The detector contains a methane sensor 1, the lower threshold elements 2 and the upper 3 levels of methane concentration, memory block 4, the output of which is connected to the first input of alarm unit 5.

New elements and connections between them are introduced into the signaling device: first 6 and second 7 coincidence circuits, shaper 8 of a pulse of a given duration and shaper 9 of a read pulse.

The signaling unit 5 (Fig. 2) contains logic elements 10-12, and the key transistor 13 is connected to the output of the circuit 12, to the collector of which the signaling LED 14 is connected, connected by its anode to the power supply. Elements 10 and 11 form a modulation frequency pulse generator, which is defined by capacitance 15 and resistor 16. One input of element 11 is connected through capacitor 17 and transistor 18 to the output of memory block 4, the other input of element 11 is connected to output of threshold element 3 of the upper level of methane .

The detector works as follows.

In the case of gas-dynamic phenomena (a sudden ejection of coal and gas), methane concentration C (t) enters sensor 1, the value of which increases rapidly with time (graph A on Lig. 3). The signal from the output of sensor 1 is fed to the inputs of the threshold elements of the lower 2 and upper 3 levels of methane concentration. The first is triggered by a threshold element 2 of the lower level of methane concentration, which is adjusted to a setting value of 1.8 rev.% CH.

At the moment element 2 triggers, the voltage at its output varies abruptly from the voltage of the logical unit to the voltage of the logic mp. This starts the shaper 8 of a pulse of a given duration, which produces a pulse of 1 second duration (this value can be changed by setting the detector). The logical zero signal from the output of the threshold element 2 also goes to one of the inputs of the first matching circuit 6.

After the triggering of the threshold element 3 of the upper level of methane concentration (it is triggered after the threshold element 2 at a concentration of 2.0% by volume SNd, as the concentration of methane continues to increase), the signal of the logical unit c-output of the threshold element 3 goes to the signaling unit 5, wherein the generator on the logic elements 10 and 11 starts producing pulses that are supplied to the alarm LED 14 through the logic element 12 and the transistor 13. In this case, the LED turns on in time with these pulses.

The frequency of the pulses is determined by the capacitance 15 and the resistor 16, as well as

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capacity 17 and the state of transi tor; 18.

Also, the logic signal ed1pszy from the output of the threshold element 3 is fed to another input of the first circuit

6 matches, at the first input of which there will be a logical signal (ul from the output of the threshold element 2. As a result, at the output of the first circuit 6 there will be an impulse I, a logical zero, the duration of which is equal to the time interval between the trigger elements of the threshold elements

2 and 3. This logical zero pulse is fed to one input of the second circuit.

7 matches, and at its other input comes a pulse Hg of a logical unit of a given duration 1 from the output of the imaging unit 8.

 If the time interval between the response times of the threshold -elements 2 and 3 is less than 1 s, then at the time of the second circuit 7 of the match there will be a pulse AND of a logical unit with a duration equal to the difference of the durations of the pulses at the inputs of the circuit 7 of coincidence. This impulse of a logical unit arrives at one of the inputs of memory block 4, and an AND signal of a logical unit is set at its output.

If the growth rate of methane concentration is less than the setpoint, i.e., the duration of the interval between pulses at the inputs of the first coincidence circuit 6 is greater than 1 s, then the output of the second coincidence circuit 7 will be a logical zero voltage that will not cause a change in state nor at the output of the memory block 4. In this case, the signaling of exceeding the setpoint for methane concentration of 2.0 vol.% With a frequency of 1 Hz (graph B in Fig. 3) will work, since the transistor 18 will be closed.

When a logical unit pulse appears at the output of memory block 4 and respectively at the input of signaling unit 5, transistor 18 opens and capacitor 17 is connected to a generator on logic elements 10 and 11. At the same time, the frequency of its pulses increases to 2 Hz (voltage Id the output of the logic element 12).

Consequently, when an alarm is triggered by the rate of increase in the concentration of methane, the light signaling operates at a higher frequency

following pulses (ignition will occur until the concentration of methane drops below 2 vol.%, threshold element 3 is measured, the voltage at its output changes from a logical unit to a logical zero, the read pulse driver 9 generates a short pulse And the logical unit to the second input of memory block 4 and the voltage at its output will change from logical unit to logical zero (return to the initial state). The voltage of the logical zero will go to the generator inputs on elements 10 and 11 of the 5 sig unit alizatsii and signaling otklyuchits.

The setpoint for the alarm triggering speed can be changed by adjusting the pulse duration at the output of the imaging unit 8 or the triggering settings of the threshold elements 2 and 3. In this case, the speed setting is 0.2 vol.% / S, since the difference between the triggering parameters of the threshold elements 3 and 2 equals

and the pulse duration is on

0.2 rev .;

Shaper output 8 is 1 s.

In fact, the detector registers the rate of increase in the concentration of methane at a point of 2 vol%. This allows one to get rid of false alarms when bursts of methane concentration less than 2 vol.%, Which increases the reliability of the signaling device.

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Portable iijaxTH (ni signal; methane congestion containing methane sensor, threshold elements of the lower and upper levels of methane concentration, memory block, alarm unit, the output of which is connected to the first input, the sensor of methane connected to the inputs of the threshold elements, and the output of the block The memory is connected to the first input of the alarm unit, characterized in that, in order to improve the accuracy of the assessment of the degree of danger of the gas situation, it contains the first and second coincidence circuits, the read pulse generator, one input of the first the coincidence circuit is connected to the output of the lower level element of methane concentration and to the input of a pulse shaper of a given duration, the second input of the first coincidence circuit is connected to the output of the threshold element of the upper level of methane concentration, the input of the read pulse shaper and the second input of the alarm unit, the first input of the second coincidence circuit is connected with the output of the first matching circuit, the second input with the output of the pulse shaper of a given duration, the memory unit is connected by the first input to the output in Ora coincidence circuit and the second input - to the output of the read pulse.

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Claims (1)

Claim Portable Mine Alarm 5 methane containing a methane sensor, threshold elements of the lower and upper levels of methane concentration, a memory unit, an alarm unit, the output of which is connected to the first input, 1Q and the methane sensor output is connected to the inputs of the threshold elements, and the output of the memory unit is connected to the first input of the alarm unit It is important that, in order to increase the accuracy of assessing the degree of danger of a gas situation, it contains the first and second coincidence circuits, a read pulse shaper, and one input of the first connection coincidence circuit is connected to the output of the threshold element of the lower level of methane concentration and to the input of the pulse shaper of a given duration, the second input of the first matching circuit is connected 25 to the output of the threshold element of the upper level of methane concentration, the input of the read pulse shaper and the second input of the signaling unit, the first input of the second matching circuit is connected to the output of the first matching circuit, the second input with the output of the pulse shaper of a given duration, the memory unit is connected by the first input to the output of the second matching circuit, and the second input with the output of the read pulse shaper.