CN2816780Y - Smart gas-leakage detection device - Google Patents

Abstract

A kind of intelligent gas leakage detecting apparatus, comprise that gas piping clamps part, is installed in the coal gas measuring and controlling device that clamps part, also comprise two ultrasonic transducers, microprocessor, valve-off, the output connecting microprocessor of two ultrasonic transducers, valve-off are installed in the porch of gas piping; Two ultrasonic transducers be installed in clamp part to side position; Microprocessor comprises the shut-off valve driver element that sends and receive switch unit, time measurement unit, information storage part, comparative analysis unit, sends out code to valve-off when the comparative analysis unit judges is gas leak, sends the telecommunication unit of leakage alarm after the comparative analysis unit judges is gas leak to maintenance department.The utility model provide a kind of can be automatically, in real time to gas leak detect, highly sensitive, can realize that air feed does not have crushing and measures, installs intelligent gas leakage detecting apparatus simply and easily.

Description

Intelligent gas leakage detecting apparatus

(1) technical field

The utility model belongs to the application in the town gas safety precaution of ultrasonic detection technology, control technology and infotech, is applicable to town gas supplier's the safe way and the safe gas of using of each use city piped gas family.

(2) background technology

In recent years, coal gas is come into huge numbers of families and is made assurance for city dweller's modernization life.Can enjoy coal gas citizen and bring people simultaneously easily, the someone swallows the bitter pill of gas leak frequently also.According to relevant department, enter certain city of China from coal gas in 1993 since, almost annual this city has tens people and even tens people die in accident to leak the coal gas.The city of the early stage import pipe coal gas of China is faced with a large amount of maintenance works with gas safety because pipeline and sebific duct etc. enter the ageing step at present.The gas supply network has brought much simultaneously easily to urban life in a word, also draw some new security hidden troubles, if deal with improperly or untimely pinpointing the problems all may be given the city people's lives and properties at any time just as the bomb that does not detonate and be threatened.

Clearly propose in the nation-building portion " fairly well-off urban and rural housing scientific and technological industry engineering city demonstration quarter planning and design guide rules (revision) in 2000 ": " promote to use the research and development of outdoor metering (moisture, electric, gas meter, flow meter technology) and product energetically." for this reason the research of intelligent meter data recording system paid close attention to; utilize the electronic technology computing machine; network technology and sensing technology; to traditional ammeter; water meter; gas meter, flow meter is improved, make it become remote installed meter, adorn a cover metering system out of doors, the data that each gauging table sensor is spread out of, deliver to the collector storage of each table and deliver to the system synthesis unit through functional transformation, each unit is by data bus and connect, any point computing machine direct dialogue on data bus, automatically copy and accept three table data, the appearance of these researchs and product is all hunted leak automatically for coal gas good hardware foundation is provided, the particularly development of ultrasonic flow detection technique in recent years is the instantaneous delivery of coal gas, the detection of big flow provides a kind of new means.

Existing inspection to gas leak mainly is by manual mode or uses instrument to hunt leak.Also the shortcoming of Cun Zaiing is: 1, to the Leak Detection of coal gas user internal pipeline because workload is big and the user stays out and can't hunt leak, find that simultaneously the promptness of gas leak is poor, can not detect in real time; When 2, detecting, all need directly to contact, during measurement there is crushing in air feed with ducted coal gas; 3, in some family the gas leak sensor has been installed at present, after indoor coal gas reaches finite concentration, sensor moves, warning tells the user that coal gas leaks, this method can improve the level of safe usefulness gas, but still be a kind of prevention method of passive type after all, need the people to go to intervene in case find to report to the police, the preventive effect that the position that gas leak takes place in addition exceeds gas leak sensor investigative range gas leak has also just lost, and can not find coal gas micro-leakage situation, poor sensitivity; 4, can not detect the coal gas adverse current; 5, when the installation and measuring instrument, need use needs special valve, flange and by-pass line, and installation trouble and expense are higher.

(3) summary of the invention

In order to overcome can not detecting in real time, find that the gas leak promptness is poor, when measuring air feed being existed the deficiency of crushing, poor sensitivity, installation trouble of gas leakage detecting apparatus in the prior art, the utility model provide a kind of can be automatically, in real time gas leak is detected, can detect gas speed ground subtle change, highly sensitive, can realize that air feed does not have crushing and measures, installs intelligent coal gas leakage automatic detection device simply and easily.

The technical scheme that its technical matters that solves the utility model adopts is:

A kind of intelligent gas leakage detecting apparatus, comprise that gas piping clamps part, is installed in the coal gas measuring and controlling device that clamps part, also comprise two ultrasonic transducers, microprocessor, the output of valve-off, two ultrasonic transducers connects described microprocessor, and described valve-off is installed in the porch of gas piping; Described two ultrasonic transducers be installed in clamp part to side position, the forward ultrasonic transducer is near user's use side of gas piping, the negative sense ultrasonic transducer is away from user's use side of gas piping;

Described microprocessor comprises:

Optionally one of them is a transmitter with two ultrasonic transducer ground when prosecution, another is the transmission of receiver and receives switch unit;

Be transmitted into following current travel-time t that negative sense ultrasonic transducer receive with the metering that the reception switch unit is connected from the forward ultrasonic transducer with transmission ₁ ^l, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^lThe time measurement unit;

Be transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer when being used to deposit the coal gas stationary state ₁, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂Information storage part;

The comparative analysis unit is used for the following current travel-time t that metering units is measured ₁ ^l, adverse current travel-time t ₂ ^lWith t ₁, t ₂Subtract computing, i.e. following formula:

${\mathrm{\ϵ}}_1=t_1-t_1^l;$ ${\mathrm{\ϵ}}_2=t_2-t_2^l$ Formula 1;

And according to following current travel-time t ₁ ^l, adverse current travel-time t ₂ ^lAnd the relation between the flow velocity u of piped gas, its relational expression is:

$t_1^l=\frac{D/\sin \mathrm{\θ}}{c_2+u\cos \mathrm{\θ}}+\mathrm{\τ}$ Formula 2;

$t_2^l=\frac{D/\sin \mathrm{\θ}}{c_2-u\cos \mathrm{\θ}}+\mathrm{\τ}$ Formula 3;

In the following formula 2 and 3, u is the flow velocity of coal gas in the pipeline, with rice second ^-1Be unit; c ₂Be the velocity of sound of ultrasound wave in static coal gas, with rice second ^-1Be unit; D is the internal diameter of pipeline, is unit with rice; θ is the refraction angle that acoustic beam enters coal gas, and τ is represented by formula 4:

$\mathrm{\τ}=2\frac{l_1}{c_1}+{\mathrm{\τ}}_e$ Formula 4;

In the following formula 4, l ₁Being the length of acoustic conductance, is unit with rice; c ₁Be the velocity of sound of ultrasound wave in acoustic conductance, with rice second ^-1Be unit;

Being the time of ultrasonic pulse by acoustic conductance, is unit with the second, τ _eBe circuit delay time;

If following formula 1 calculates | ε ₁|=| ε ₂| and ε ₁＞0 and ε ₂＜0, comparative analysis unit output gas leak signal;

At the shut-off valve driver element of comparative analysis unit output gas leak signal to valve-off transmission out code,

Behind comparative analysis unit output gas leak signal, send the telecommunication unit of leakage alarm to maintenance department by remote communication interface.

Further, described comparative analysis unit also comprises coal gas adverse current judging unit, if following formula 1 calculates | and ε ₁|=| ε ₂| and ε ₁＜0 and ε ₂＞0, then export coal gas adverse current signal;

Behind comparative analysis unit output coal gas adverse current signal, send the shut-off valve driver element of out code to valve-off;

Described telecommunication unit also is included in the adverse current Alarm Unit that the adverse current alarm signal is sent behind the comparative analysis unit output coal gas adverse current signal to maintenance department by remote communication interface.

Further again, described comparative analysis unit also comprises the drift judging unit, if following formula 1 calculates | and ε ₁| ≠ | ε ₂|, then export shifted signal;

Described microprocessor also comprises: auto compensation unit is used for calculating in the comparative analysis unit | ε ₁| ≠ | ε ₂|, if ε ₁≠ 0, then with t ₁ ^lNumerical value be stored in storage unit and replace t ₁Initial value; If ε ₂≠ 0, then with t ₂ ^lNumerical value be stored in storage unit and replace t ₂Initial value.

Further, the following current travel-time t of described information storage part ₁, adverse current travel-time t ₂Comprise in 1 year the following current travel-time t of every day when coal gas does not use ₁ ^d, adverse current travel-time t ₂ ^d

The comparative analysis unit is used for the following current travel-time t that metering units is measured ₁ ^l, adverse current travel-time t ₂ ^lWith the t that detects the same day ₁ ^d, t ₂ ^dSubtract computing, i.e. following formula:

${\mathrm{\ϵ}}_1^d=t_1^d-t_1^l;$ ${\mathrm{\ϵ}}_2^d=t_2^d-t_2^l$ Formula 5;

If following formula 5 calculates $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|$ And ${\mathrm{\&epsiv;}}_1^d>0$ And ${\mathrm{\&epsiv;}}_2^d<0,$ Comparative analysis unit output gas leak signal.

Further, described comparative analysis unit also comprises coal gas adverse current judging unit,

If following formula 5 calculates $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|$ And ${\mathrm{\&epsiv;}}_1^d<0$ And ${\mathrm{\&epsiv;}}_2^d>0,$ Then export coal gas adverse current signal;

Behind comparative analysis unit output coal gas adverse current signal, send the shut-off valve driver element of out code to valve-off;

It is the adverse current Alarm Unit that after the coal gas adverse current adverse current alarm signal is sent to maintenance department by remote communication interface that described telecommunication unit also is included in the comparative analysis unit judges.

Further again, described comparative analysis unit also comprises the drift judging unit, if following formula 5 calculates $\left|{\mathrm{\&epsiv;}}_1^d\right|\&NotEqual;\left|{\mathrm{\&epsiv;}}_2^d\right|,$ Just be judged as the drift that ultrasonic sensor produced through the time;

Described microprocessor also comprises: auto compensation unit is used for calculating in the comparative analysis unit $\left|{\mathrm{\&epsiv;}}_1^d\right|\&NotEqual;\left|{\mathrm{\&epsiv;}}_2^d\right|,$ If ${\mathrm{\&epsiv;}}_1^d\&NotEqual;0,$ Then with t ₁ ^lNumerical value be stored in storage unit and replace t ₁ ^dInitial value; If ε ₂≠ 0, then with t ₂ ^lNumerical value be stored in storage unit and replace t ₂ ^dInitial value.

Further, described microprocessor also comprises the flow rate calculation unit, is used to receive the output of described time measurement unit and obtains the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^l-t_1^l$ After, record the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{D_c}_2^2\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 6

In the following formula 6, D is the cross section internal diameter of gas piping, is unit with rice; C ₂Be the velocity of sound of ultrasound wave in static coal gas, with rice second ^-1Be unit; θ is the refraction angle that acoustic beam enters coal gas; Δ t is the concurrent-countercurrent propagation time difference, is unit with the second; Q is the flow of coal gas, with rice ³Hour ^-1Be unit.

Described microprocessor also comprises: described telecommunication unit comprises that also the flow of the coal gas that the flow rate calculation unit is recorded sends the automatic charging unit of charging center to by remote communication interface.

The beneficial effects of the utility model mainly show: 1, adopt ultrasonic sensor (transducer) that the flow of gas situation is detected, and can be automatically, in real time gas leak is detected, can detect gas speed ground subtle change, highly sensitive; 2, ultrasonic transducer is installed in and clamps part, adopts indirect measurement method, can realize that air feed does not have crushing and measures; 3, installation and maintenance are convenient, and the installation and maintenance that clamp the formula transducer all need not arrheaed, and do not need special valve, flange and by-pass line, and erected cost is low; 4, utilize time difference method to detect the variation of gas speed, can survey positive and negative two, for the adverse current of finding coal gas provides a kind of means to stream; 5, can detect the subtle change of flow velocity, provide visual means the real-time monitoring of whole coal gas webmaster; 6, be particularly suitable for the heavy caliber flow measurement, price is little with the variation of bore, and ultrasonic flow meter is good and cheap, and time difference ultrasonic flow meter can be surveyed caliber and reach 10.7 meters, and the gas flow that can satisfy each node on the coal gas webmaster detects; 7, measure be not stressed, density, the isoparametric influence of viscosity, the output characteristics linear range is wide; 8, no movable member does not have wearing and tearing, and long service life is in light weight; 9, adopt microprocessor, can carry out automatically because environment temperature, sensor zero point drift equal error compensation and computing can be carried out the refraction angle and revise, and self-diagnostic function is arranged.

(4) description of drawings

Fig. 1 is the basic comprising schematic diagram of intelligent gas leakage detecting apparatus.

Fig. 2 is the cut-away view of microprocessor.

Fig. 3 is the process flow diagram of microprocessor of the intelligent gas leakage detecting apparatus of embodiment 1.

Fig. 4 is the process flow diagram of microprocessor of the intelligent gas leakage detecting apparatus of embodiment 2.

(5) embodiment

Below in conjunction with accompanying drawing the utility model is further described.

Embodiment 1

With reference to Fig. 1, Fig. 2, Fig. 3, a kind of intelligent gas leakage detecting apparatus, comprise that gas piping clamps part 2, is installed in the coal gas measuring and controlling device that clamps part 2, this coal gas measuring and controlling device comprises the output connecting microprocessor 6 of two ultrasonic transducers 3, microprocessor 6, valve-off 4, two ultrasonic transducers 3, and valve-off 4 is installed in the porch of gas piping 1; Two ultrasonic transducers 3 be installed in clamp part 2 to side position, the forward ultrasonic transducer is near user's use side of gas piping, the negative sense ultrasonic transducer is away from user's use side of gas piping; Microprocessor 6 comprises shut-off valve driver element 5, telecommunication part 7, IO interface 8, internal bus 9, clock 10, ROM storer 11, RAM storer 12, computing unit CPU 13,

Measurement for gas flow, in order to simplify installation and to reduce cost, the utility model adopts a pair of ultrasonic transmitter and receiver, both alternations are in emission, accepting state, in the coal gas that ultrasound wave is flowing, with respect to fixed coordinate system, ultrasonic velocity is different with the velocity of propagation in static immobilising coal gas, mistiming by measurement following current and the propagation of adverse current ultrasonic pulse is measured coal gas at ducted instantaneous delivery, device has two ultrasonic transducer R and T respectively in the pipeline both sides, and ducted coal gas flows forward with speed μ.Two transducer alternations among the figure are called the following current emission state in emission, accepting state when T emission R receives, otherwise R emission T is called the adverse current emission state when receiving.If the travel-time of ultrasonic pulse is t during the following current emission ₁ ^l, and the travel-time of adverse current when emission ultrasonic pulse is t ₂ ^l

(flow Q=0) is transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer when being used to deposit the coal gas stationary state ₁, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂Information storage part, described information storage part is divided into the part of ROM storer 11; Microprocessor comprises: optionally one of them is a transmitter with two ultrasonic transducer ground when prosecution, another is the transmission of receiver and receives switch unit; Computing unit CPU 13 comprises time measurement unit, comparative analysis unit, and the time measurement unit is connected with the reception switch unit with transmission, is used to measure from the forward ultrasonic transducer be transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives ₁ ^l, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^lThe comparative analysis unit is used for the following current travel-time t that metering units is measured ₁ ^l, adverse current travel-time t ₂ ^lWith t ₁, t ₂Subtract computing, i.e. following formula:

${\mathrm{\&epsiv;}}_1=t_1-t_1^l;$ ${\mathrm{\&epsiv;}}_2=t_2-t_2^l$ Formula 1; And according to following current travel-time t ₁ ^l, adverse current travel-time t ₂ ^lAnd the relation between the flow velocity u of piped gas, its relational expression is:

$t_1^l=\frac{D/\sin \mathrm{\&theta;}}{c_2+u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 2;

$t_2^l=\frac{D/\sin \mathrm{\&theta;}}{c_2-u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 3;

In the following formula 2 and 3, u is the flow velocity of coal gas in the pipeline, with rice second ^-1Be unit; c ₂Be the velocity of sound of ultrasound wave in static coal gas, with rice second ^-1For unit (generally speaking $c_2^2>>{\mathrm{\&mu;}}^2$ ); D is the internal diameter of pipeline, is unit with rice; θ is the refraction angle that acoustic beam enters coal gas, and τ is represented by formula 4:

$\mathrm{\&tau;}=2\frac{l_1}{c_1}+{\mathrm{\&tau;}}_e$ Formula 4;

In the following formula 4, l ₁Being acoustic conductance (O-P) or length (B-C), is unit with rice; c ₁Be the velocity of sound of ultrasound wave in acoustic conductance, with rice second ^-1Be unit; Being the time of ultrasonic pulse by acoustic conductance, is unit with the second, τ _eBe circuit delay time;

If following formula 1 calculates | ε ₁|=| ε ₂| and ε ₁＞0 and ε ₂＜0, then be judged as gas leak;

When being gas leak, the comparative analysis unit judges sends the shut-off valve driver element of out code to valve-off,

After being gas leak, the comparative analysis unit judges sends the telecommunication unit of leakage alarm to maintenance department by remote communication interface.

Described comparative analysis unit also comprises coal gas adverse current judging unit, if following formula 1 calculates | and ε ₁|=| ε ₂| and ε ₁＜0 and ε ₂＞0, then be judged as the coal gas adverse current; It is the adverse current Alarm Unit that after the coal gas adverse current adverse current alarm signal is sent to maintenance department by remote communication interface that telecommunication unit also is included in the comparative analysis unit judges.

Described comparative analysis unit also comprises the drift judging unit, if following formula 1 calculates | and ε ₁| ≠ | ε ₂|, just be judged as the drift that ultrasonic sensor produced through the time; Described microprocessor also comprises: auto compensation unit is used for calculating in the comparative analysis unit | ε ₁| ≠ | ε ₂|, if ε ₁≠ 0, then with t ₁ ^lNumerical value be stored in storage unit and replace t ₁Initial value; If ε ₂≠ 0, then with t ₂ ^lNumerical value be stored in storage unit and replace t ₂Initial value.

With reference to Fig. 3, the course of work of the intelligent gas leakage detecting apparatus of present embodiment is:

The first step judges that whether minimum flow was arranged in one day is 0, if having then judge gas leak takes place not, and because flow is 0,1 Δ t is 0 according to formula, does not drift about so be judged as ultrasonic sensor;

In second step, when judging that minimum flow in one day is non-vanishing, the time measurement unit of microprocessor is by sending and receive the following current travel-time t of switch unit to two ultrasonic transducers ₁ ^l, the adverse current travel-time is measured t ₂ ^l, and from microprocessor, obtain system time;

In the 3rd step,, when obtaining measuring the coal gas stationary state on the same day, the information storage part of microprocessor is transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer according to system time ₁, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂

In the 4th step, calculate ${\mathrm{\&epsiv;}}_1=t_1-t_1^l,$ ${\mathrm{\&epsiv;}}_2=t_2-t_2^l,$

In the 5th step, relatively judge whether to exist: | ε ₁|=| ε ₂|;

The 6th step, if | ε ₁|=| ε ₂| and ε ₁＞0 and ε ₂＜0, be judged as gas leak; When being gas leak, the comparative analysis unit judges sends out code to valve-off; And send alarm signal, the maintenance of notice maintenance department of information center to the information center of gas distribution plant;

If | ε ₁|=| ε ₂| and ε ₁＜0 and ε ₂＞0, then be judged as the coal gas adverse current; Drive shut-off valve and cut off gas supply, and, notify the maintenance of maintenance department by the place that coding rule finds gas piping to break;

If | ε ₁| ≠ | ε ₂|, just be judged as the drift that ultrasonic sensor produced through the time; If ε ₁≠ 0, then with t ₁ ^lNumerical value be stored in storage unit and replace t ₁Initial value; If ε ₂≠ 0, then with t ₂ ^lNumerical value be stored in storage unit and replace t ₂Initial value, carry out drift compensation.

Described microprocessor also comprises the flow rate calculation unit, is used to receive the output of described time measurement unit and obtains the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^l-t_1^l$ After, record the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{D_c}_2^2\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 6

In the following formula 6, D is the cross section internal diameter of gas piping, is unit with rice; C ₂Be the velocity of sound of ultrasound wave in static coal gas, with rice second ^-1Be unit; θ is the refraction angle that acoustic beam enters coal gas; Δ t is the concurrent-countercurrent propagation time difference, is unit with the second; Q is the flow of coal gas, with rice ³Hour ^-1Be unit.

Described microprocessor also comprises: described telecommunication unit comprises that also the flow of the coal gas that the flow rate calculation unit is recorded sends the automatic charging unit of charging center to by remote communication interface.

Embodiment 2

With reference to Fig. 1, Fig. 2, Fig. 4, the hardware configuration of present embodiment is identical with embodiment 1.

Be used for depositing 1 year every day during the coal gas stationary state (flow Q=0) be transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer ₁ ^d, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^dInformation storage part, described information storage part is divided into the part of ROM storer 11;

Microprocessor comprises: optionally one of them is a transmitter with two ultrasonic transducer ground when prosecution, another is the transmission of receiver and receives switch unit; Be transmitted into following current travel-time t that negative sense ultrasonic transducer receive with the metering that the reception switch unit is connected from the forward ultrasonic transducer with transmission ₁ ^l, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^lThe time measurement unit; The comparative analysis unit is used for the following current travel-time t that metering units is measured ₁ ^l, adverse current travel-time t ₂ ^lWith the t that detects the same day ₁ ^d, t ₂ ^dSubtract computing, i.e. following formula:

${\mathrm{\&epsiv;}}_1^d=t_1^d-t_1^l;$ ${\mathrm{\&epsiv;}}_2^d=t_2^d-t_2^l$ Formula 5;

And according to following current travel-time t ₁ ^l, adverse current travel-time t ₂ ^lAnd the relation between the flow velocity u of piped gas, its relational expression is:

$t_1^l=\frac{D/\sin \mathrm{\&theta;}}{c_2+u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 2;

$t_2^l=\frac{D/\sin \mathrm{\&theta;}}{c_2-u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 3;

In the following formula 2 and 3, u is the flow velocity of coal gas in the pipeline, with rice second ^-1Be unit; c ₂Be the velocity of sound of ultrasound wave in static coal gas, with rice second ^-1For unit (generally speaking $c_2^2>>{\mathrm{\&mu;}}^2$ ); D is the internal diameter of pipeline, is unit with rice; θ is the refraction angle that acoustic beam enters coal gas, and τ is represented by formula 4:

$\mathrm{\&tau;}=2\frac{l_1}{c_1}+{\mathrm{\&tau;}}_e$ Formula 4:

In the following formula 4, l ₁Being acoustic conductance (O-P) or length (B-C), is unit with rice; c ₁Be the velocity of sound of ultrasound wave in acoustic conductance, with rice second ^-1Be unit; Being the time of ultrasonic pulse by acoustic conductance, is unit with the second, τ _eBe circuit delay time;

If following formula 5 calculates $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|$ And ${\mathrm{\&epsiv;}}_1^d>0$ And ${\mathrm{\&epsiv;}}_2^d<0,$ Be judged as gas leak:

When being gas leak, the comparative analysis unit judges sends the shut-off valve driver element of out code to valve-off,

After being gas leak, the comparative analysis unit judges sends the telecommunication unit of leakage alarm to maintenance department by remote communication interface.

Described comparative analysis unit also comprises coal gas adverse current judging unit, if following formula 5 calculates $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|$ And ${\mathrm{\&epsiv;}}_1^d<0$ And ${\mathrm{\&epsiv;}}_2^d>0,$ Then be judged as the coal gas adverse current; It is the adverse current Alarm Unit that after the coal gas adverse current adverse current alarm signal is sent to maintenance department by remote communication interface that described telecommunication unit also is included in the comparative analysis unit judges.

Described comparative analysis unit also comprises the drift judging unit, if following formula 5 calculates $\left|{\mathrm{\&epsiv;}}_1^d\right|\&NotEqual;\left|{\mathrm{\&epsiv;}}_2^d\right|,$ Just be judged as the drift that ultrasonic sensor produced through the time; Described microprocessor also comprises: auto compensation unit is used for calculating in the comparative analysis unit $\left|{\mathrm{\&epsiv;}}_1^d\right|\&NotEqual;\left|{\mathrm{\&epsiv;}}_2^d\right|,$ If ${\mathrm{\&epsiv;}}_1^d\&NotEqual;0,$ Then with t ₁ ^lNumerical value be stored in storage unit and replace t ₁ ^dInitial value; If ε ₂≠ 0, then with t ₂ ^lNumerical value be stored in storage unit and replace t ₂ ^dInitial value.

With reference to Fig. 4, the workflow of the intelligent gas leakage detecting apparatus of present embodiment is:

The first step judges that whether minimum flow was arranged in one day is 0, if having then judge gas leak takes place not, and because flow is 0,1 Δ t is 0 according to formula, does not drift about so be judged as ultrasonic sensor;

In second step, when judging that minimum flow in one day is non-vanishing, the time measurement unit of microprocessor is by sending and receive the following current travel-time t of switch unit to two ultrasonic transducers ₁ ^l, the adverse current travel-time is measured t ₂ ^l, and from microprocessor, obtain system time;

In the 3rd step,, when obtaining measuring the coal gas stationary state on the same day, the information storage part of microprocessor is transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer according to system time ₁ ^d, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^d

In the 4th step, calculate ${\mathrm{\&epsiv;}}_1^d=t_1^d-t_1^l,$ ${\mathrm{\&epsiv;}}_2^d=t_2^d=t_2^l,$

In the 5th step, relatively judge whether to exist: $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|;$

The 6th step, if $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|$ And ${\mathrm{\&epsiv;}}_1^d>0$ And ${\mathrm{\&epsiv;}}_2^d<0,$ Be judged as gas leak; When being gas leak, the comparative analysis unit judges sends out code to valve-off; And send alarm signal, the maintenance of notice maintenance department of information center to the information center of gas distribution plant;

If $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|$ And ${\mathrm{\&epsiv;}}_1^d<0$ And ${\mathrm{\&epsiv;}}_2^d>0,$ Then be judged as the coal gas adverse current; Drive shut-off valve and cut off gas supply, and, notify the maintenance of maintenance department by the place that coding rule finds gas piping to break;

If $\left|{\mathrm{\&epsiv;}}_1^d\right|\&NotEqual;\left|{\mathrm{\&epsiv;}}_2^d\right|,$ Just be judged as the drift that ultrasonic sensor produced through the time; If ${\mathrm{\&epsiv;}}_1^d\&NotEqual;0,$ Then with t ₁ ^lNumerical value be stored in storage unit and replace t ₁ ^dInitial value; If ε ₂≠ 0, then with t ₂ ^lNumerical value be stored in storage unit and replace t ₂ ^dInitial value, carry out drift compensation.

Described microprocessor also comprises the flow rate calculation unit, is used to receive the output of described time measurement unit and obtains the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^l-t_1^l$ After, record the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{D_c}_2^2\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 6

In the following formula 6, D is the cross section internal diameter of gas piping, is unit with rice; C ₂Be the velocity of sound of ultrasound wave in static coal gas, with rice second ^-1Be unit; θ is the refraction angle that acoustic beam enters coal gas; Δ t is the concurrent-countercurrent propagation time difference, is unit with the second; Q is the flow of coal gas, with rice ³Hour ^-1Be unit.

Described microprocessor also comprises: described telecommunication unit comprises that also the flow of the coal gas that the flow rate calculation unit is recorded sends the automatic charging unit of charging center to by remote communication interface.

The utility model intelligent gas leakage detecting apparatus can also be as a kind of intelligent gas meter with remote meter-reading function when finishing the gas leak detection automatically, this intelligence gas meter is owing to have ambient temperature compensation and drift compensation function, thereby has measuring accuracy height, automatic straightening, intelligent functions such as demarcation automatically.

Claims (3)

1, a kind of intelligent gas leakage detecting apparatus, comprise that gas piping clamps part, is installed in the coal gas measuring and controlling device that clamps part, it is characterized in that: microprocessor, valve-off that whether this coal gas measuring and controlling device comprises two ultrasonic transducers, leaks in order to the signal monitoring coal gas according to ultrasonic transducer, the output of two ultrasonic transducers connects described microprocessor, described valve-off is installed in the porch of gas piping, described microprocessor signals output terminal connection closed valve, and by remote communication interface connection maintenance department.

2, the described intelligent gas leakage detecting apparatus of claim 1 is characterized in that: described microprocessor also comprises in order to the flow rate calculation unit according to the calculated signals flow of ultrasonic transducer.

3, intelligent gas leakage detecting apparatus as claimed in claim 2 is characterized in that: described microprocessor comprises that also the flow that is used for coal gas that the flow rate calculation unit is recorded sends the automatic charging unit of charging center to by remote communication interface.

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