RU2340002C1 - Fire early detection method and device for implementing method - Google Patents

Abstract

FIELD: physics; fire safety.

SUBSTANCE: device for implementing the proposed method of early detection of fire, consists of sensors for concentration of gas components in air, matching amplifiers, analogue-to-digital converters, a microprocessor, light and sound alarm signal generator, light and sound signalling device, generator output, connected to the central fire prevention concentrator, modulation code generator, driving generator, phase manipulator, power amplifier and a transmitting antenna. The device for receiving signals with phase manipulation, put in the fire emergency and/or at the observation control point, has a receiving antenna, high frequency amplifier, heterodyne, mixer, intermediate frequency amplifier, di-phase splitter, two narrow-band filters, phase doubler, 90 phase shifter, phase detector and a recording unit.

EFFECT: wider zone of monitoring fire safety objects and modern transmission of alarm signals from fire safety objects to the fire emergency and to the observation control unit by using a radio channel and complex signals with phase manipulation.

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Description

The proposed method and device relates to the field of fire safety and can be used to detect fire in the early stages of smoldering and ignition of combustible materials.

Known methods for detecting fire using fire detectors that respond to the action of an open flame or smoke and generate an alarm (G.M. Zuykov. Inspector of state fire surveillance, fire alarm. M .: Stroyizdat, 1988). These include light, responsive to light or infrared radiation of the fire; thermal, reacting to temperature increase in case of fire; and smoke detectors that respond to increasing concentrations of smoke particles.

However, these detectors are not effective enough, because when they are used, an alarm is generated relatively late, when the fire is already quite developed. In addition, these detectors do not exclude the possibility of false alarms when the temperature rises or dusts the premises that are not associated with a fire.

The reaction time of a fire detector to the start of a fire can be reduced by using gas fire detectors that respond to gases generated at the initial stage of smoldering of combustible materials that can freely escape from closed cavities in which a fire occurred.

Known methods (VMAroutiounian, ZNAdamian, HVAbovian. Thin film smoke sensuy element, The Sixth Yntemational Meeting on Chemical Sensors, 1996, Yuli 22-25, Gaitherburg, Md, USA, p.103) fire detection using one non-selective gas a sensor that responds to a mixture of gases that may be generated by the smoldering of combustible materials. The use of such sensors is limited by the high probability of false signals from such detectors when exposed to, for example, solvent vapors.

A known method of early detection of fire and a device for its implementation (DE, C2, 3.123.279), which consists in the fact that continuously measure the current value of the concentration of carbon monoxide released during smoldering of combustible materials, compare it with a predetermined allowable value of the specified concentration and if it matches these values form an alarm.

However, in the indicated technical solutions, only those values of carbon monoxide concentration that exceed the average value of its concentration in this room are used to generate an alarm. In addition, when the alarm is generated, only those deviations of the CO concentration from the average value are taken into account, the frequency of which lies in the interval characteristic of a fire. They do not exclude the possibility of generating an alarm signal during the accumulation of CO as a result of the operation of furnaces, smoking, as well as in other cases of increased CO emission not related to fire.

Methods and devices for early fire detection are also known (RF patents Nos. 2,207.631, 2.110.094, 2.078.377, 2.177.179, 2.256.228, 2.256.231; US patents Nos. 5,049.861, 5.079.422; patent EP No. 0.940.679; patent WO No. 9.948.070; Sharovar F. I. Fire alarm devices and systems. - M .: Stroyizdat, 1985, pp. 292-295 and others).

Of the known methods closest to the proposed is the "Method of early detection of fire" (RF patent No. 2.256.228, G08B 17/10, 2001), which is selected as a prototype.

The specified method reduces the likelihood of receiving a false signal at the initial stage of ignition. This is achieved by simultaneously measuring and analyzing the concentrations of at least two gas components released during the smoldering of combustible materials and which are most characteristic of the initial stage of the fire, and by generating an alarm signal when the values of the ratios of the concentrations of gas components coincide with the set ones.

A device that implements the known method contains at least two sensors for the concentration of gas components released during smoldering, a microprocessor and an alarm driver.

The disadvantages of this method are the limited monitoring zone of fire safety facilities in areas where there are no wired and fiber-optic communication lines, as well as the untimely transmission of an alarm signal from fire safety facilities to the fire department and to the control tower.

An object of the invention is the expansion of the monitoring zone of the object in fire safety and the timely transmission of alarms from fire safety objects to the fire department and / or to the control room by using a radio channel and complex signals with phase shift keying.

The problem is solved in that the method of early fire detection, based in accordance with the closest analogue on the fact that measure the current concentration in the air of gas components selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide and aromatic hydrocarbons released during smoldering combustible materials, determine the ratio of the measured concentrations of gas components, which is compared with its predetermined value, while an alarm is generated when the specified values coincide of the concentration of gas components, differs from the nearest analogue in that, along with an alarm, they generate a high-frequency oscillation and a modulating code that displays the identification number of the fire safety object and its coordinates, manipulate the high-frequency oscillation in phase with a modulating code, and amplify the generated complex signal with phase manipulation in power , emit it on the air, catch it at the control tower and / or in the fire service, convert it by frequency, divide by phase into two, select dissolved harmonic oscillation at frequency w _pr / 2, double its phase is isolated harmonic oscillation at intermediate frequency w _pr shifted its phase by 90 ° and used as the reference voltage for the synchronous detection of the received signal with phase shift keying at the intermediate frequency, is isolated and register a low-frequency voltage proportional to the modulating code.

The problem is solved in that a device for early fire detection, containing, in accordance with the closest analogue, n sensors for concentration in the air of gas components released during the smoldering of combustible materials, each sensor being connected via a series-connected matching amplifier and an analog-to-digital converter to a microprocessor, connected to the alarm driver and designed to compare the current values of the concentrations of gas components measured by sensors with the formation of the ratio of current concentration values and comparing the generated ratio with its predetermined value, differs from the closest analogue in that it is equipped with a modulating code generator at the fire safety facility, a master oscillator, a phase manipulator, a power amplifier and a transmitting antenna, and to the second output of the microprocessor in series a master oscillator, a phase manipulator, the second input of which is connected through the generator of the modulating code to the second the output of the microprocessor, a power amplifier and a transmitting antenna, and at the control room and / or in the fire department a receiving antenna, a high-frequency amplifier, a local oscillator, a mixer, an intermediate frequency amplifier, a phase divider into two, two narrow-band filters, a phase doubler, a 90 phase shifter °, a phase detector and a registration unit, and a high-frequency amplifier, a mixer, the second input of which is connected to the local oscillator output, is connected in series to the output of the receiving antenna, th frequency divider, two, the first narrow-band filter, a phase doubler, the second narrow-band filter, a 90 ° phase shifter, a phase detector, the second input of which is connected to the output of the intermediate frequency amplifier, and a registration unit.

Temporal dependences of the concentrations of the main gas components released during smoldering of cotton are shown in FIG. Temporal dependences of the concentrations of the main gas components released during smoldering of wood are depicted in FIG. 2. The structural diagram of a device for early fire detection is presented in figure 3. The block diagram of a device for receiving a complex signal with phase shift keying, containing information about the objects where a fire occurs, is presented in figure 4. Timing diagrams explaining the principle of operation of the devices shown in figure 5.

A device for early fire detection contains n channels, each of which is designed to measure the concentration of one gas component and contains a sensor in the form, for example, of a gas sensor 1.i (i = 1, 2, ..., n), which are connected in series coupled matching amplifier 2.i and analog-to-digital converter 3.i. The output of each analog-to-digital converter 3.i is connected to the corresponding input of the microprocessor 4 connected to the shaper 5 of light and sound alarms, equipped with a light 6 and sound 7 signaling devices, while the output 8 of the shaper 5 is connected to a central fire protection concentrator (not shown) . The number of channels depends on the number of gas components, the concentrations of which are measured simultaneously at the initial stage of ignition. A modulator code generator 9, a phase manipulator 11, the second input of which is connected to the output of the microprocessor 4 through a master oscillator 10, a power amplifier 12, and a transmitting antenna 13 are connected to the second output of the microprocessor 4.

A device for receiving complex signals with phase shift keying (QPSK) contains a receiving antenna 14 connected in series, a high-frequency amplifier 15, a mixer 17, the second input of which is connected to the output of the local oscillator 16, an intermediate frequency amplifier 18, a phase divider 19 into two, the first narrow-band filter 20 , a phase doubler 21, a second narrow-band filter 22, a 90 ° phase shifter 23, a phase detector 24, the second input of which is connected to the output of the intermediate frequency amplifier 18, and a recording unit 25.

A device for receiving complex QPSK signals is installed at the control room and / or in the fire service.

A device for early fire detection can be implemented on well-known elements of domestic and foreign production, such as semiconductor sensors such as PGS-1 or Model 911 sensors from Sieger (Germany), MICS 1110 from Motorola (USA), microprocessors like P1C12C509- And Motorola firms, standard AD9202 ADCs from Analog Deviees (1999 catalog) and indicators of different brands.

The proposed method is implemented as follows.

It has been established that the initial stages of smoldering and ignition of most known combustible materials are characterized by the evolution of gas components, the main of which are hydrogen (H ₂ ), carbon monoxide (CO), carbon dioxide (CO ₂ ) and aromatic hydrocarbons (C _x H _y ), and the concentrations of these gases vary over time.

The experimentally obtained time dependences of the concentrations of hydrogen, carbon monoxide, carbon dioxide and aromatic hydrocarbons in the air in the first few minutes after the start of smoldering of cotton and wood are shown in FIGS. 1 and 2, where K is the current value of the concentration of the gas component in air in%.

Analysis of the graphs shows that during the first minutes of smoldering, there is a sharp gas evolution simultaneously of several gases, namely hydrogen, aromatic hydrocarbons, carbon monoxide and carbon dioxide.

The values of the concentration of emitted gases for different combustible materials may be different, but the release of carbon monoxide is always accompanied by the release of hydrogen, aromatic hydrocarbons and carbon dioxide. In this case, the values of the ratios of the concentrations of the listed gases lie within certain limits.

It is established that in the first 2-3 minutes of the beginning of the smoldering process of the main combustible materials, the ratios of the concentrations in the air of aromatic hydrocarbons, hydrogen, carbon monoxide and carbon dioxide at each current time point are:

.

.

Moreover, the values of the ratio of concentrations, for example, hydrogen and carbon monoxide are in the range of 1: 2.4-5.6 at each current point in time.

The above ratios of the concentrations of the main gas components are selected as the specified ratios of quantities with which the ratio of the current concentrations of these components is compared, and if they coincide, an alarm is generated.

Each of the semiconductor gas sensors 1.1-1.n, sensitive to the effects of one of the listed gas components (H ₂ , CO, CO ₂ and C _x H _y ), changes its conductivity with a change in the concentration of this component in air, resulting in an output of the corresponding sensor 1.1-1.n an electrical signal appears, the value of which corresponds to a certain concentration of this gas component in the air. Then this signal is amplified and converted using the appropriate Converter 3.1.-3.n into a digital signal.

The microprocessor 4 continuously or with a predetermined frequency, for example, after 0.1-1 minute polls the sensors 1.1-1.n, compares the current signal values (corresponding to the current values of the concentration of gas components in the air) received from them and the obtained ratios of the current signal values compares with predetermined ratios of signal values recorded earlier and stored in its memory. If the ratios of the current values of the signals coincide with the specified ratios of values, the shapers 5 and 9 receive signals that generate alarms on them: light, sound, as well as the signal supplied from output 8 to the central fire protection concentrator, and the modulating code M (t), showing the identification number of the fire safety facility, respectively.

The device generates a steady alarm in the second or third minutes after the start of artificial induced decay of building debris selected as combustible material. For example.

In the first minute of smoldering construction debris, consisting of rags with a predominant cotton content, the ratio was:

in the third minute:

Accordingly, the ratio of hydrogen and carbon monoxide in the first minute:

and in the third minute:

When smoldering construction waste with a predominant composition of wood (shavings, wood chips, veneer) in the first minute, the ratio:

in the third minute:

на первой минуте и

на третьей минуте.Ratio

in the first minute and

in the third minute.

When the ratio of the current concentration values of the main gas components with the given ratios coincides, a signal is generated in the microprocessor 4, which from its second output is fed to the input of the master oscillator 10 and turns it on.

The master oscillator 10 generates a high-frequency oscillation (figure 5, a)

U _c (t) = V _c cos (w _ct + φ _c ), 0≤t≤T _c ,

where V _c , W _c , φ _c , T _c , is the amplitude, carrier frequency, initial phase, and duration of the high-frequency oscillation, which is fed to the second input of the phase manipulator 11, the first input of which is supplied with a modulating code M (t) from the output of the shaper 9 (Fig.5, b), displaying the identification number of the fire safety facility.

At the output of the phase manipulator 11, a complex QPSK signal is generated (Fig. 5, c)

U ₁ (t) = V _c · cos [w _ct + φ _k (t) + φ _c ], 0≤t≤T _c ,

where φ _k (t) = {0, π} is the manipulating component of the phase that displays the law of phase manipulation in accordance with the modulating code M (t) (Fig. 5, b), and φ _k (t) = const for kτ _e < t <{k + 1) τ _e and can change stepwise at t> kτ _e i.e. at the borders between elementary premises (k = 1,2, ..., N);

τ _e , N is the duration and number of chips that make up a signal of duration T _c (N · τ _e = T _s ), which, after amplification in the power amplifier 12, enters the antenna 13, is transmitted to the air, is captured by the receiving antenna 14 and through the high-frequency amplifier 15 is fed to the first input of the mixer 17, the second input of which the local oscillator voltage 16

U _g (t) = V _g cos (w _gt + φ _g ).

At the output of the mixer 17, voltage of combination frequencies is formed. The amplifier 18 is allocated the voltage of the intermediate (differential) frequency (figure 5, g)

,

,

;Where

;

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

φ _CR = φ _s -φ _g ,

which is fed to the information input of the phase detector 24. A necessary condition for the synchronous detection of the PSK signal U _pr (t) is the presence of a reference voltage having the same intermediate frequency w _pr and a constant initial phase φ _pr In the proposed device, the reference voltage is extracted directly from the PSK signal itself. To do this, the voltage U _CR (t) from the output of the intermediate frequency amplifier 18 is supplied to the input of the phase divider 19 into two.

It should be noted that the manipulated phase component φ _k (t) in the voltage U _CR (t) can be represented as follows

φ _k (t) = Δφ · E (t)

where Δφ = 90 °

E (t) is a function that determines the law of phase change.

For simplicity, we assume that the function E (t) is periodic with a period T equal to twice the duration τ _{e of} elementary premises

T = 2 τ _e , i.e.

.

.

The expansion of the function E (t) in a Fourier series has the following form

.

.

The output voltage of the divider 19 phase into two will take place the following voltage

With binary phase manipulation, i.e. when φ _k (t) = {0, π}, Δφ = 90 °, the PSK signal U _CR (t) does not contain in its spectrum oscillations of the intermediate frequency w _CR , since cos 90 ° = 0.

At the output of the phase divider 19 into two, a component of the intermediate frequency w _pr appears in the spectrum of the obtained voltage U ₂ (t), since cos (Δφ / 2) = cos45 ° = 0.707, and the voltage will have the following form (Fig. 5, d) U ₃ (t) = V ₂ · cosΔφ / 2 · sin (w _pr / 2t + φ _pr /2)=0.707 · V ₂ · sin (w _pr / 2t + φ _pr / 2) = V ₃ sin (w _pr / 2t + φ _pr / 2),

where V ₃ = 0.707 · V ₂ .

This voltage is allocated by a narrow-band filter 20 and is fed to the input of the phase doubler 21, at the output of which a harmonic voltage is generated.

₄ U (t) = V ₄ · sin (w t + φ _{pr pr),} 0≤t≤T _s,

,Where

,

which is allocated by a narrow-band filter 22 and is fed to the input of the phase shifter 23 by 90 °. At the output of the latter a harmonic voltage is generated (Fig. 5, e)

U ₅ (t) = V ₄ · sin (w _pr t + φ _pr + 90 °) = V ₄ · cos (w _pr t + φ _pr ), 0≤t≤T _c ,

which is used as the reference voltage and is fed to the reference input of the phase detector 24, to the information input of which the PSK signal U _pr (t) (Fig. 5d) is supplied from the output of the intermediate frequency amplifier 18.

As a result of synchronous detection at the output of the phase detector 24, a low-frequency voltage is generated (Fig. 5, g).

U _n (t) = V _n cosφ _k (t), 0≤t≤T _c ,

Where

proportional to the modulating code M (t) (Fig. 5, b), which is fixed by the registration unit 25.

Thus, the proposed method, in comparison with the prototype and other technical solutions of a similar purpose, provides the expansion of the monitoring zone of fire safety facilities and the timely transmission of an alarm from fire safety facilities to the fire department and / or to a dispatching observation point.

This is achieved using a radio channel and complex phase-shift signals.

These signals allow the use of structural selection. This means that it becomes possible to separate signals operating in the same frequency band and at the same time intervals.

, тогда как ширина спектра Δf_c ФМн-сигнала определяется длительностью τ_э, его элементарных посылок

, т.е. ширина спектра второй гармоники сигнала в N раз меньше ширины спектра Δf_c входного сигнала (Δf_c/Δf₂=N).The width of the spectrum Δf _{2 of the} second harmonic is determined by the duration T _{c of the} signal

, while the width of the spectrum Δf _c FMN signal is determined by the duration τ _{e of} its elementary premises

, i.e. the spectrum width of the second harmonic of the signal is N times smaller than the spectrum width Δf _{c of the} input signal (Δf _c / Δf ₂ = N).

Consequently, as a result of dividing the phase by two and doubling the phase of the QPSK signal, its spectrum “folds” N times. This makes it possible to detect the QPSK signal even when its power at the receiver input is less than the power of interference and noise. In addition, due to narrow-band filtering, it is possible to filter a significant part of noise and interference, and thereby increase the sensitivity of the receiver.

In the well-known A. A. Pistolkors circuit, which also provides the selection of the reference voltage necessary for the synchronous detection of the applied PSK signal directly from the signal itself, there is “reverse operation”. This is explained by the fact that in this circuit, due to the frequency doubler, the phase manipulation is completely erased, i.e. the signal is destroyed. Therefore, the generated reference voltage from the destroyed signal does not have strict coherence with the QPSK signal, which is why “reverse work” occurs, i.e. the low-frequency signal at the output of the phase detector is perceived as “negative”: zeros instead of ones and vice versa.

In the proposed receiver, the QPSK signal is fed to a phase divider, and not to a frequency doubler. Therefore, the QPSK signal is not destroyed, but its phase deviation only decreases, as a result of which an intermediate frequency oscillation appears, which is strictly in phase with the QPSK signal. The latter eliminates the “reverse work” and increases the reliability of the allocation of low-frequency voltage proportional to the modulation code M (t).

Simultaneous monitoring of several gases increases the reliability of fire detection precisely in the early stages of smoldering and ignition. This eliminates the possibility of false alarms of the measuring device when increasing the concentration of one of the gases for any of the reasons that do not correspond to the ignition process. The latter is possible, for example, as a result of leakage of gases from cylinders, tanks or pipelines located inside or near the protected premises.

Claims (2)

1. The method of early fire detection, based on the fact that measure the current value of the concentration in the air of gas components selected from the group consisting of hydrogen, carbon monoxide, carbon dioxide and aromatic hydrocarbons released during smoldering of combustible materials, determine the ratio of the measured concentrations of gas components , which is compared with its predetermined value, while an alarm is generated when the indicated values of the ratios of the concentration of gas components coincide, characterized in that comfort along with an alarm signal, a high-frequency oscillation and a modulating code that displays the identification number of the fire safety object and its coordinates, manipulate the high-frequency oscillation in phase with a modulating code, amplify the generated complex signal with phase manipulation in power, radiate it to the air, pick it up at the control room and / or in the fire service, they are frequency-converted, phase-divided by two, a harmonic frequency oscillation w _pr / 2 is distinguished, its phase is doubled, a harmonic count is allocated frigged intermediate frequency w, _etc., it is shifted in phase by 90 ° and used as the reference voltage for the synchronous detection of the received signal with phase shift keying at the intermediate frequency, allocate and record the low-frequency voltage proportional to the modulating code. 2. A device for early fire detection, containing n sensors of concentrations in the air of gas components released during the smoldering of combustible materials, each sensor through a series-connected matching amplifier and an analog-to-digital converter is connected to a microprocessor connected to an alarm clipper and designed for comparison the current values of the concentrations of the gas components measured by the sensors with the simultaneous formation of the ratios of the current values of concentrations and introducing the generated relationship with its predetermined value, characterized in that it is equipped with a modulating code generator, a master oscillator, a phase manipulator, a power amplifier and a transmitting antenna at the fire safety facility, and a master oscillator, a phase manipulator, the second input of which is connected in series to the second output of the microprocessor through the shaper of the modulating code connected to the second output of the microprocessor, a power amplifier and a transmitting antenna, and at the control room and in the fire service with a receiving antenna, a high-frequency amplifier, a local oscillator, a mixer, an intermediate frequency amplifier, a phase divider into two, two narrow-band filters, a phase doubler, a 90 ° phase shifter, a phase detector and a registration unit, and to the output of the receiving antenna a high-frequency amplifier, a mixer, the second input of which is connected to the local oscillator output, an intermediate-frequency amplifier, a phase divider into two, a first narrow-band filter, a phase doubler, and a second narrow-band are connected in series filter, phase shifter 90 °, a phase detector, a second input coupled to an output of intermediate frequency amplifier, and a recording unit.

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