CN1773236A - Gas leakage automatic detecting method - Google Patents

Abstract

The present invention relates to an automatic detection method of gas leakage. Said method includes the following steps: (1), using tree net structure to represent urban gas pipe network, dividing into family household, housing entrance, pressure-regulating station and gas supply station; (2), on the joint of family household mounting domestic gas meter with closing valve, whose gas consumption data can be remotely read; and on other joint mounting flow detection device with closing valve, whose gas input quantity and gas flow can be read; every detection device is connected with information centre of gas supply station; (3), if the input quantity of some joint is greater than output quantity of next joint belonging to said joint, on said joint the gas is leaked; and (4) the information center can give out instruction for closing valve to said joint, finally, when the gas leakage is automatically detected by household joint, the valve can be automatically closed, and an alarm signal can be transferred to the maintenance centre.

Description

Gas leakage automatic detecting method

(1) technical field

The invention belongs to the application in the town gas safety precaution of ultrasonic detection technology, the network communications technology and infotech, be 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 leakage 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 the gas leakage accident.In November, 1998, a tame building constructor in this city operates against regulations in construction, the underground gas pipeline is dug split, and causes gas leakage, 8 people's death, and 27 people poison.In Dec, 1998, certain street in this city causes the gas leakage accident because cruelty is constructed, 4 people's death among the constructor, and 6 people poison.In November, 1999, certain street underground gas main line in this city is dug leakage, and gas blowout was for up to 6 hours, and dangerous situation takes place in nearly ten thousand square metres area on every side.2000, the gas leakage accident took place in certain sub-district in this city, caused people's death, two people to poison.In March calendar year 2001, the gas leakage accident takes place in certain street in this city, causes 9 people's gas poisoning death.In March, 2002, certain community resident building coal gas sebific duct in this city comes off, and gas leakage takes place, and causes 2 people's death.2003, the gas leakage accident took place in certain sub-district in this city, causes 2 people's death, 27 people to poison in various degree.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.

Oneself is through clearly proposing 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.

Inspection to gas leakage before the present invention makes mainly is by manual mode or uses instrument to hunt leak.Gas leakage generally can be divided into the leakage that gas piping in the coal gas course of conveying is revealed (pipeline is responsible for, pipeline branch pipe) and coal gas user internal pipeline, to the gas piping in the coal gas course of conveying reveal since piping laying in the underground place that is difficult to find to reveal generation, to the leak detection of coal gas user internal pipeline because workload is big and the user stays out and can't hunt leak, the promptness of finding gas leakage simultaneously is poor, is difficult to hold the current intelligence of whole coal gas webmaster.Therefore how to pass through in time to find when ultrasound wave Automatic Measurement Technique, network communications technology and infotech realize remote meter reading the gas leakage of each node on the whole webmaster, to improving city, home-use gas safety, stop the positive effect that has of gas leakage accident.

The defective that existing gas leak detection method also exists is: 1, needs manually detect each node in the gas piping, can not be in real time, automatically coal gas is detected, and the workload that gas leakage detects is big, and finds that the validity of gas leak is poor; 2, can not find coal gas micro-leakage situation, poor sensitivity; When 3, detecting, all need directly to contact, during measurement there is crushing in air feed with ducted coal gas; 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

For overcome prior art gas leak detection method can not be in real time, the deficiency of big, the validity difference of the workload that automatically coal gas detected, detects, the invention provides a kind of can be in real time, automatically coal gas is detected, can alleviate the workload of detection, improve the gas leakage automatic detecting method of the validity of finding gas leak.

The technical solution adopted for the present invention to solve the technical problems is:

A kind of gas leakage automatic detecting method may further comprise the steps:

(1), the town gas webmaster is represented with the reticulate texture of tree type, each domestic consumer is final node, the submeter of housing unit is domestic consumer's a upper node, and the voltage regulating station of coal gas is the upper node of housing unit submeter, and gas distribution plant is the cancellated root node of tree type;

(2), the domestic gas meter can long-rangely read coal gas use amount data is installed on domestic consumer's node, described domestic gas meter is provided with valve-off; The flow detector that can read coal gas input quantity and gas flow is installed on all the other nodes, described flow detector is provided with valve-off, and described domestic gas meter and each flow detector all are communicated with the information center of gas distribution plant by telecommunication unit;

(3), upper node reads the coal gas use amount and the instantaneous gas flow of coal gas of the next node that is under the jurisdiction of this node in the time of agreement, and read the coal gas input quantity of this upper node, the coal gas input quantity of certain node is compared with the gas flow summation that is under the jurisdiction of the next each node of this node, if input quantity is represented gas leakage on this node greater than the gas flow summation;

(4), information center sends the instruction of valve-off to the node that gas leak takes place, and sends the gas leak alarm signal to maintenance department.

Further, be provided with the urban cells node between described gas pressure-regulating station and the housing unit, the nodes encoding of town gas webmaster is that 10 figure places (also can be more than 10 figure places, can be according to the size of city size) coding: the 1st to 2 is the coding of gas supply tiny node, according to the distribution situation number consecutively to the coal gas webmaster; The the 3rd to 4 is the coding of voltage regulating station node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same supply station, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The the 5th to 6 is the coding of urban cells node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same voltage regulating station, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The the 7th to 8 is the coding of housing unit node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same urban cells, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The the 9th to 10 is the coding of domestic consumer's node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same housing unit, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The coding corresponding address information stores of described each node is to the information storage part of microprocessor, when certain node generation gas leak, read this address of node from the coded message of this node, and this address information is sent to maintenance department by telecommunication unit.

The concrete technical scheme of domestic gas meter is: it comprises that gas piping clamps part, is installed in the gas measurement device that clamps part, this gas measurement device comprises two ultrasonic transducers, microprocessor, the output of two ultrasonic transducers connects described microprocessor, and this 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, another is the transmission and the reception switch unit of receiver in when metering; 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 ^l, and obtain concurrent-countercurrent propagation time difference Δ t=t ₂ ^l-t ₁ ^lThe time measurement unit; The flow rate calculation unit after being used to receive the concurrent-countercurrent propagation time difference Δ t of described time measurement unit output, records the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D\; c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">D</figure-callout>}}_{c_{}}^{{}_2}\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 1;

In the following formula 1, 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; The flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of information center to; Be used to receive the valve driving unit of the long-range closing/Open valve instruction of information center.

The concrete technical scheme of flow detector is: it comprises that gas piping clamps part, is installed in the coal gas measuring and controlling device that clamps part, this coal gas measuring and controlling device comprises two ultrasonic transducers, microprocessor, the output of two ultrasonic transducers connects described microprocessor, and this 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, another is the transmission and the reception switch unit of receiver in when metering; Be transmitted into following current travel-time that negative sense ultrasonic transducer receive, t 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 that the forward ultrasonic transducer receives, t from the negative sense ultrasonic transducer ₂ ^l, and obtain the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^l-t_1^l$ The time measurement unit; The flow rate calculation unit after being used to receive the concurrent-countercurrent propagation time difference Δ t of described time measurement unit output, records the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D\; c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">D</figure-callout>}}_{c_{}}^{{}_2}\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 1;

In the following formula 1, 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; The flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of information center to; Be used to receive the valve driving unit of the long-range closing/Open valve instruction of information center.

Further, the microprocessor of described domestic gas meter and flow detector also comprises: be used for depositing and be transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer during coal gas stationary state 1 year every day 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; The comparative analysis unit is used for the following current travel-time t that metering units is measured ₁ ^l, the adverse current travel-time, t ₂ ^lT with the same day ₁ ^d, t ₂ ^dSubtract computing, i.e. following formula:

$\begin{array}{cc}{\mathrm{\&epsiv;}}_1^d=t_1^d-t_1^l;& {\mathrm{\&epsiv;}}_2^d=t_2^d-t_2^l\end{array}$ Formula 2;

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:

$t_1^l=\frac{D/\sin \mathrm{\&theta;}}{{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">c</figure-callout>}}_2+u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 3;

$t_2^l=\frac{D/\sin \mathrm{\&theta;}}{c_2-u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 4;

In the following formula 3 and 4, 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 ^-1Being that 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 5:

$\mathrm{\&tau;}=2\frac{l_1}{{\mathrm{<figure-callout\; id="1"\; label="c"\; filenames="A20041006818800301.png,A20041006818800311.png"\; state="\{\{state\}\}">c</figure-callout>}}_1}+{\mathrm{\&tau;}}_e$ Formula 5;

In the following formula 5, 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 2 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 the comparative analysis unit judges is gas leak, send the shut-off valve driver element of out code, after the comparative analysis unit judges is gas leak, send the telecommunication unit of leakage alarm to information center by remote communication interface to valve-off.

Further again, described comparative analysis unit also comprises coal gas adverse current judging unit, if following formula 2 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 information center by remote communication interface that described telecommunication unit also is included in the comparative analysis unit judges.

Further, described comparative analysis unit also comprises the drift judging unit, if following formula 2 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.

The microprocessor of described domestic gas meter also comprises: the flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of charging center to.

The device of on each node of coal gas webmaster, all being furnished with the metering gas flow, the information center of gas distribution plant can be by the communication network (cable television network in city, ADSL, VPN, Netcom etc.) read coal gas use amount and the instantaneous gas flow of coal gas on each node, and be kept in the database of gas supply station message center, generally the time of detecting in night as gas leakage in morning (agreement constantly) carries out, so that analytic statistics from now on, in order to obtain coal gas use amount and the instantaneous gas flow of coal gas on each node when the synchronization, upper node reads the coal gas use amount and the instantaneous gas flow of coal gas of the next node that is under the jurisdiction of this node in the time of agreement, the result of reading in is submitted to the upper node that it is subordinate to, simultaneously this node is carried out gas leakage and detect, therefore to family, gas leakage during branch gas tube and coal gas are responsible for can be used multiple detection mode; 1) whether the use total amount of detecting unit submeter is identical with the dispensed amounts of coal gas dispensing station, and whether be used for detecting gas main has leakage; 2) whether the use amount of detecting unit submeter is identical with the use amount summation of each submeter that enters family, and whether be used for detecting branch gas tube has leakage; 3) whether the unit submeter has above the maximum instantaneous gas flow, is used for analyzing the leakage possibility of this node and child node; 4) whether the submeter of each family has above the maximum instantaneous gas flow, is used for analyzing the leakage possibility of home (e) node; 5) whether (time in morning) has flow to take place in the non-use coal gas time, is used for confirming whether leakage is arranged on each node; 6) whether instantaneous coal gas backflow phenomenon taking place, was used for analyzing the position of gas leakage on certain node.

Beneficial effect of the present invention mainly shows: 1, in the time of agreement, can carry out gas leak to each node and detect, and can be in real time, automatically coal gas is detected; 2,, can significantly reduce the workload of detection with respect to the manual detection in the prior art; 3, by to the use amount of each node and the detection of coal gas instantaneous delivery, improve the validity of finding gas leak; 4, when detecting gas leak, can this node valve-off of Long-distance Control, and send leakage alarm to maintenance department, security is good; 5, the flow detector on domestic gas meter and all the other nodes has adopted ultrasonic transducer as flow sensor, and is highly sensitive, can detect the subtle change of flow velocity, provides visual means to the real-time monitoring of whole coal gas webmaster; 6, can survey positive and negative two to stream, for the adverse current of finding coal gas provides a kind of means; 7, ultrasonic transducer is installed in pipeline and clamps part, measures gas flow indirectly, can realize that air feed does not have crushing and measures; 8, 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; 9, measure be not stressed, density, the isoparametric influence of viscosity, the output characteristics linear range is wide; 10, no movable member does not have wearing and tearing, and long service life is in light weight; 11, 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; 12, 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; 13, because the measuring accuracy of ultrasonic sensor is relevant with the pipe thickness and the material of tested pipeline, if the inside pipe wall corrosion seriously all can influence measuring accuracy, can utilize this characteristic to diagnose the gas pipe inwall corrosion order of severity conversely, to improve the town gas pipe safety.

(4) description of drawings

Fig. 1 is the synoptic diagram that gas leak may take place on the coal gas webmaster.

Fig. 2 is the system topology figure of coal gas webmaster.

Fig. 3 is the structure principle chart of domestic gas meter.

Fig. 4 is the structure principle chart of flow detector.

Fig. 5 is the structural drawing of microprocessor.

Fig. 6 is the process flow diagram of ultrasound examination gas leak.

Fig. 7 is that the throughput ratio of node when not having gas leak is than synoptic diagram.

Throughput ratio when Fig. 8 is node generation gas leak is than synoptic diagram.

Fig. 9 is the structural representation of the gas leak detection system of coal gas webmaster.

(5) embodiment

Below in conjunction with accompanying drawing the present invention is further described.

With reference to Fig. 1, Fig. 2, a kind of gas leakage automatic detecting method may further comprise the steps:

(1), the town gas webmaster is represented with the reticulate texture of tree type, each domestic consumer is final node, the submeter of housing unit is domestic consumer's a upper node, and the voltage regulating station of coal gas is the upper node of housing unit submeter, and gas distribution plant is the cancellated root node of tree type;

(2), the domestic gas meter can long-rangely read coal gas use amount data is installed on domestic consumer's node, described domestic gas meter is provided with valve-off; The flow detector that can read coal gas input quantity and gas flow is installed on all the other nodes, described flow detector is provided with valve-off, and described domestic gas meter and each flow detector all are communicated with the information center of gas distribution plant by telecommunication unit;

(3), upper node reads the coal gas use amount and the instantaneous gas flow of coal gas of the next node that is under the jurisdiction of this node in the time of agreement, and read the coal gas input quantity of this upper node, the coal gas input quantity of certain node is compared with the gas flow summation that is under the jurisdiction of the next each node of this node, if input quantity is represented gas leakage on this node greater than the gas flow summation;

(4), information center sends the instruction of valve-off to the node that gas leak takes place, and sends the gas leak alarm signal to maintenance department.

With reference to Fig. 2, be provided with the urban cells node between described gas pressure-regulating station and the housing unit, the nodes encoding of town gas webmaster is the coding of 10 figure places: the 1st to 2 is the coding Node1 of gas supply tiny node, according to the distribution situation number consecutively to the coal gas webmaster; The the 3rd to 4 is the coding Node2 of voltage regulating station node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same supply station, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The the 5th to 6 is the coding Node3 of urban cells node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same voltage regulating station, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The the 7th to 8 is the coding Node4 of housing unit node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same urban cells, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The the 9th to 10 is the coding Node5 of domestic consumer's node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same housing unit, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers; The coding corresponding address information stores of described each node is to the information storage part of microprocessor, when certain node generation gas leak, read this address of node from the coded message of this node, and this address information is sent to maintenance department by telecommunication unit.

Comprise also that with reference to Fig. 3, domestic gas meter gas piping clamps part, is installed in the gas measurement device that clamps part, this gas measurement device comprises two ultrasonic transducers, microprocessor, the output of two ultrasonic transducers connects described microprocessor, and this 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, another is the transmission and the reception switch unit of receiver in when metering; 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 ^l, and obtain the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^l-t_1^l$ The time measurement unit; The flow rate calculation unit after being used to receive the concurrent-countercurrent propagation time difference Δ t of described time measurement unit output, records the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D\; c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">D</figure-callout>}}_{c_{}}^{{}_2}\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 1;

In the following formula 1, 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; The flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of information center to; Be used to receive the valve driving unit of the long-range closing/Open valve instruction of information center.

Flow detector with reference to Fig. 4, all the other nodes comprises that also gas piping clamps part, is installed in the coal gas measuring and controlling device that clamps part, this coal gas measuring and controlling device comprises two ultrasonic transducers, microprocessor, the output of two ultrasonic transducers connects described microprocessor, and this 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, another is the transmission and the reception switch unit of receiver in when metering; 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 ^l, and obtain the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^l-t_1^l$ The time measurement unit; The flow rate calculation unit after being used to receive the concurrent-countercurrent propagation time difference Δ t of described time measurement unit output, records the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;}{\mathrm{<figure-callout\; id="2"\; label="D\; c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">D</figure-callout>}}_{c_{}}^{{}_2}\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 1;

In the following formula 1, 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; The flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of information center to; Be used to receive the valve driving unit of the long-range closing/Open valve instruction of information center.

The microprocessor of domestic gas meter and flow detector also comprises: be used for depositing and be transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer during coal gas stationary state 1 year every day 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; 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 ^lT with the same day ₁ ^d, t ₂ ^dSubtract computing, i.e. following formula:

$\begin{array}{cc}{\mathrm{\&epsiv;}}_1^d=t_1^d-t_1^l;& {\mathrm{\&epsiv;}}_2^d=t_2^d-t_2^{\mathrm{<figure-callout\; id="2"\; label="l\; Formula"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">l</figure-callout>}}& \\ \end{array},$ Formula 2;

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:

$t_1^l=\frac{D/\sin \mathrm{\&theta;}}{{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">c</figure-callout>}}_2+u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 3;

$t_2^l=\frac{D/\sin \mathrm{\&theta;}}{c_2-u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 4;

In the following formula 3 and 4, 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 5:

$\mathrm{\&tau;}=2\frac{l_1}{c_1}+{\mathrm{\&tau;}}_{\mathrm{<figure-callout\; id="5"\; label="e\; Formula"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">e</figure-callout>}}$ Formula 5;

In the following formula 5, 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, consider generally speaking ${\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">c</figure-callout>}}_2^2>>{\mathrm{\&mu;}}^2;$ If following formula 2 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 the comparative analysis unit judges is gas leak, send the shut-off valve driver element of out code, after the comparative analysis unit judges is gas leak, send the telecommunication unit of leakage alarm to information center by remote communication interface to valve-off.

Described comparative analysis unit also comprises coal gas adverse current judging unit, if following formula 2 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 information center 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 2 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.

The microprocessor of domestic gas meter also comprises: the flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of charging center to.

With reference to Fig. 6, the course of work of the gas leak of domestic gas meter of the present invention and flow detector:

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 since flow be 0, according to formula l then Δ t be 0, do 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 $\begin{array}{cc}{\mathrm{\&epsiv;}}_1^d=t_1^d-t_1^l,& {\mathrm{\&epsiv;}}_2^d=t_2^d-t_2^l,\end{array}$

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 incite somebody to action 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;

If $\left|{\mathrm{\&epsiv;}}_1^d\right|=\left|{\mathrm{\&epsiv;}}_2^d\right|,$ And ${\mathrm{\&epsiv;}}_1^d<0$ Simultaneously ${\mathrm{\&epsiv;}}_2^d<0,$ Perhaps ${\mathrm{\&epsiv;}}_1^d>0$ Simultaneously ${\mathrm{\&epsiv;}}_2^d>0,$ Be judged as the drift that the ultrasonic sensor generation produces through other reasons, and carry out corresponding compensation.

Foot is the finish node of webmaster among Fig. 9, and the domestic gas meter on finish node Node5 in (family) comprises coal gas measure portion 1, communications portion 2, shut-off valve 3, shut-off valve driver element 4; On housing unit node Node4, comprise ultrasound wave coal gas use amount detection table 5, calculating section 6, telecommunication part 7, information storage part 8, shut-off valve 9, shut-off valve driver element 10; On the node of the Node3 of voltage regulating station of coal gas, comprise information storage part 14, shut-off valve 15, shut-off valve driver elements 16 such as ultrasound wave gas flow pick-up unit 11, application data server 12, telecommunication service 13, the use of coal gas amount; On the node Node1 in the supply station of coal gas, comprise ultrasound wave gas flow pick-up unit 17, application data server 18, telecommunication service 19, preserve information storage part 20, the communication network 21 that links each node, shut-off valve 22, shut-off valve driver element 23 such as coal gas amount use on each node; The node Node4 that does not comprise urban cells herein, when including the urban cells node, on the urban cells node, comprise ultrasound wave coal gas use amount detection table, calculating section, telecommunication part, information storage part, shut-off valve, shut-off valve driver element; For the ease of calculating in the gas using quantity table in coal gas use amount on each node is kept at the gas supply station message center by the tree of coal gas actual flow the information storage part 20,10 bit numbers of each node have been write down in the table, detection time, the number of degrees (the GasUserID of instantaneous delivery and gas meter, MeasureTime, InsFlow, GasGross), read the instantaneous delivery on each node and the number of degrees of gas meter by communication network 21, be saved in then in the gas using quantity table, carrying out the inspection of gas leakage after having read data calculates, when on finding certain node, having the gas leakage situation to take place, the shut-off valve driver element work that starts this node by communication network 21 makes the shut-off valve action cut off the coal gas source, uses gas thereby ensure safety.

Referring to Fig. 3, Fig. 4, measurement for gas flow, in order to simplify installation and to reduce cost, the present invention 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.

Can obtain entering one day the coal gas use amount Q of each submeter of family in the through type 1 _XxxxxxxxxxxAnd one day coal gas use amount Q of unit submeter _Xxxxxxxxx00, whether the use amount of detecting unit submeter is identical with the use amount summation of each submeter that enters family, wherein one day coal gas use amount Q of each family's submeter _XxxxxxxxxxxWith one day coal gas use amount of housing unit submeter, $Q_{\mathrm{xxxxxxxxxxx}}={\mathrm{GasGross}}_{\mathrm{day}}^{\mathrm{node}5}-{\mathrm{GasGross}}_{\mathrm{day}-1}^{\mathrm{<figure-callout\; id="5"\; label="node"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">node</figure-callout>}5}$ Formula 6

$Q_{\mathrm{xxxxxxxxx}00}={\mathrm{GasGross}}_{\mathrm{day}}^{\mathrm{node}4}-{\mathrm{GasGross}}_{\mathrm{day}-1}^{\mathrm{<figure-callout\; id="4"\; label="node"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">node</figure-callout>}4}$ GasGross in formula 7 formulas 6, the formula 7 _Day ^Node5For certain family measured the number of degrees of gas meter, GasGross the same day _Day-1 ^Node5For certain family measures the number of degrees of gas meter, GasGross the previous day _Day ^Node4For the housing unit submeter was measured the number of degrees of gas meter, GasGross the same day _Day-1 ^Node4Measure the number of degrees of gas meter the previous day for the housing unit submeter, work as Q _Xxxxxxxxx00=∑ Q _XxxxxxxxxxThe time, show at the housing unit branch gas tube and do not reveal, otherwise gas leakage is arranged; Further again, the leakage that detects coal gas on urban cells (secondary trunk) the webmaster road also is to use same quadrat method, the flow that detects coal gas on urban cells (secondary trunk) the webmaster road whether with the unit submeter the use amount summation identical, one day coal gas use amount Q of each housing unit submeter wherein _Xxxxxxxxx00And the coal gas use amount Q of urban cells (secondary trunk) webmaster road last one day _Xxxxxxx0000,

$Q_{\mathrm{xxxxxxx}0000}={\mathrm{GasGross}}_{\mathrm{day}}^{\mathrm{node}3}-{\mathrm{GasGross}}_{\mathrm{day}-1}^{\mathrm{<figure-callout\; id="3"\; label="node"\; filenames="A20041006818800351.png"\; state="\{\{state\}\}">node</figure-callout>}3}$ Formula 8

GasGross in the formula 8 _Day ^Node3For measuring the number of degrees of gas meter, GasGross on urban cells (secondary trunk) the webmaster road same day _Day-1 ^Node3For measuring the number of degrees of gas meter on urban cells (secondary trunk) the webmaster road the previous day, work as Q _Xxxxxxx0000=∑ Q _Xxxxxxxx00The time, show that coal gas is not revealed on urban cells (secondary trunk) webmaster road, otherwise gas leakage is arranged; Further again, detection leakage of coal gas from the gas pressure-regulating station webmaster road also is to use same quadrat method, whether the flow that detects coal gas on the gas pressure-regulating station webmaster road is identical with use amount summation on urban cells (secondary trunk) the webmaster road, wherein the coal gas use amount Q of urban cells (secondary trunk) webmaster road last one day _Xxxxxxx0000With one day coal gas gas pushing quantity Q of gas pressure-regulating station _Xxxx000000,

$Q_{\mathrm{xxxx}000000}={\mathrm{GasGross}}_{\mathrm{day}}^{\mathrm{node}2}-{\mathrm{GasGross}}_{\mathrm{day}-1}^{\mathrm{<figure-callout\; id="2"\; label="node"\; filenames="A20041006818800311.png,A20041006818800351.png"\; state="\{\{state\}\}">node</figure-callout>}2}$ Formula 9

GasGross in the formula 9 _Day ^Node2For gas pressure-regulating station measured the number of degrees that coal gas is supplied gas, GasGross the same day _Day-1 ^Node2For gas pressure-regulating station measures the number of degrees of gas meter the previous day, work as Q _Xxxx000000=∑ Q _Xxxxxx0000The time, show that coal gas is not revealed on the gas pressure-regulating station webmaster road, otherwise gas leakage is arranged; Further, detection leakage of coal gas from gas distribution plant's backbone network pipeline also is to use same quadrat method, the supply flow that detects coal gas on the gas distribution plant webmaster road whether summation with the supply of gas pressure-regulating station is identical, wherein the coal gas gas pushing quantity Q of supply webmaster road last one day of gas pressure-regulating station _Xxxx000000With one day coal gas gas pushing quantity Q of gas distribution plant _Xx00000000,

$Q_{\mathrm{xx}00000000}={\mathrm{GasGross}}_{\mathrm{day}}^{\mathrm{node}1}-{\mathrm{GasGross}}_{\mathrm{day}-1}^{\mathrm{<figure-callout\; id="1"\; label="node"\; filenames="A20041006818800301.png,A20041006818800311.png"\; state="\{\{state\}\}">node</figure-callout>}1}$ Formula 10

GasGross in the formula 10 _Day ^Node1For gas distribution plant measured the number of degrees that coal gas is supplied gas, GasGross the same day _Day-1 ^Node1For gas distribution plant measures the number of degrees of gas meter the previous day, work as Q _Xx00000000=∑ Q _Xxxx000000The time, coal gas is not revealed on the gas pressure-regulating station webmaster road, otherwise gas leakage is arranged; Further, whether the present invention was by instantaneous coal gas backflow phenomenon took place on certain node, be used for analyzing the position of gas leakage, because ultrasonic sensor can be measured the adverse current of coal gas, if on some measured node, in a single day find to have the coal gas adverse current, and flow equations is false between above-mentioned node and its upper node, so just can confirm to take place the upper reaches location of the place of gas leakage at this node, because the present invention has the numbering of being undertaken by rule to each measured node, in the information storage part 20 of gas supply station message center, depositing the user basic information table corresponding with this numbering, depositing user name in the table, station address, essential informations such as telephone number, according to coding rule and user basic information table, just can exactly the place that gas leakage takes place be decided, so that can get rid of potential safety hazard timely.If can set up Geographic Information System at the gas supply station message center, the flow information in each monitoring point is fused in the urban geographic information system goes, just can on the urban geographic information drawing, show the supply situation of coal gas and the abnormal conditions that monitor whole gas distribution network in real time.Use finish node coal gas use amount information owing in the computing machine of gas supply station message center, preserve each coal gas, can finish the function of automatic data logging; Since in the computing machine of gas supply station message center, preserve each node on the coal gas webmaster air feed, use gas information, can provide foundation for the decision-making of science rationally by these information, make investment acquisition greatest benefit.

So-called gas leakage is full of under the whole coal gas gas grid pipeline situation at coal gas, and list is considered from some nodes, is exactly to import the output quantity of the coal gas amount of this node greater than coal gas on this node so, and we claim on this node gas leakage to have taken place; Because traditional gas meter exists measuring error, causes very big difficulty to finding micro-gas leakage, can't measure the adverse current phenomenon of coal gas; Simultaneously traditional method is checked the instantaneous delivery of each node on the whole coal gas air feed webmaster in can't be at one time, can't concern each lateral of finding on the coal gas air feed webmaster, the gas leakage on the trunk line with the supply and demand equation; The present invention is in order to solve above-mentioned several problems, consider the calculating of information, the convenience of retrieval, make up the monitor message webmaster identical with the coal gas network management framework, at the node of each monitor message webmaster to an air feed node on the coal gas webmaster should be arranged, each the air feed node coal gas input quantity of supersonic flow measuring device measurement on this node, the next each node of this node provides the output quantity information of coal gas, the gas flow summation of the next each node of the coal gas input quantity on certain node and this node is compared, Fig. 7, Fig. 8 is the situation that certain upper node Node2 has 5 child node Node3, and Q is satisfied on the top of Fig. 7 _Xxxx000000=Q _Xxxx010000+ Q _Xxxx020000+ Q _Xxxx030000+ Q _Xxxx040000+ Q _Xxxx050000The equation relation, above-mentioned equation, that is: Q are not satisfied in the bottom of Fig. 8 _Xxxx000000≠ Q _Xxxx010000+ Q _Xxxx020000+ Q _Xxxx030000+ Q _Xxxx040000+ Q _Xxxx050000In a single day when finding the rear portion of the front portion of equation greater than equation, just think that gas leakage takes place the pipeline somewhere below this node Node2, at this time will in time drive shut-off valve, cut off the gas supply of this node Node2, and overhaul by network notice maintenance department; Whether detect coal gas really reveals, particularly under the situation that micrometeor is revealed, measuring accuracy and measuring method are very crucial technology, in the present embodiment, means such as drift compensation by ultrasonic measurement and temperature and sensor, can measure the small of coal gas exactly flows, simultaneously owing to utilized ultrasound wave can survey the advantage of adverse current, also be as the criterion when can in time find gas leakage and determine that gas leakage scene in position provides new means, owing to adopted the coding techniques of node and the user base table relevant among the present invention with node, make maintenance department can find the place of gas leakage exactly, such as finding Q _Xxxx03000, Q _Xxxx050000On two nodes the adverse current phenomenon is arranged, according to the present invention in the coal gas webmaster to the coding rule of each node, the proper flow direction of coal gas is Q _Xxxx010000_ Q _Xxxx030000_ Q _Xxxx050000So, judge that easily gas leakage occurs in Q _Xxxx030000Before and Q _Xxxx010000Afterwards, then according to the data of user base table, if Q in the user base table _Xxxx010000The fragrant garden of corresponding expression rice community, Q _Xxxx030000The corresponding morning sunlight community that represents, the place that gas leakage takes place so just from the fragrant garden of rice community to morning sunlight on the intercommunal arm, in general, coal gas adverse current phenomenon takes place be not that a coal gas trace is revealed but pipeline breaking and causing, the inner pipe network in same sub-district is found to have the adverse current phenomenon also can judge in order to last method and is revealed the place that takes place.

Claims (8)

1, a kind of gas leakage automatic detecting method is characterized in that: may further comprise the steps:

(1), the town gas webmaster is represented with the reticulate texture of tree type, each domestic consumer is final node, the submeter of housing unit is domestic consumer's a upper node, and the voltage regulating station of coal gas is the upper node of housing unit submeter, and gas distribution plant is the cancellated root node of tree type;

(2), the domestic gas meter can long-rangely read coal gas use amount data is installed on domestic consumer's node, described domestic gas meter is provided with valve-off; The flow detector that can read coal gas input quantity and gas flow is installed on all the other nodes, described flow detector is provided with valve-off, and described domestic gas meter and each flow detector all are communicated with the information center of gas distribution plant by telecommunication unit;

(3), upper node reads the coal gas use amount and the instantaneous gas flow of coal gas of the next node that is under the jurisdiction of this node in the time of agreement, and read the coal gas input quantity of this upper node, the coal gas input quantity of certain node is compared with the gas flow summation that is under the jurisdiction of the next each node of this node, if input quantity is represented gas leakage on this node greater than the gas flow summation;

(4), information center sends the instruction of valve-off to the node that gas leak takes place, and sends the gas leak alarm signal to maintenance department.

2, gas leakage automatic detecting method as claimed in claim 1 is characterized in that: be provided with the urban cells node between described gas pressure-regulating station and the housing unit, the nodes encoding of town gas webmaster is the coding of 10 figure places:

The the 1st to 2 is the coding of gas supply tiny node, according to the distribution situation number consecutively to the coal gas webmaster;

The the 3rd to 4 is the coding of voltage regulating station node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same supply station, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers;

The the 5th to 6 is the coding of urban cells node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same voltage regulating station, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers;

The the 7th to 8 is the coding of housing unit node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same urban cells, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers;

The the 9th to 10 is the coding of domestic consumer's node, arranges from small to large according to the flow of gas direction that is under the jurisdiction of same housing unit, and to two side flow, a side is an odd number as coal gas, and opposite side is even numbers;

The coding corresponding address information stores of described each node is to the information storage part of microprocessor, when certain node generation gas leak, read this address of node from the coded message of this node, and this address information is sent to maintenance department by telecommunication unit.

3, gas leakage automatic detecting method as claimed in claim 2, it is characterized in that: described domestic gas meter comprises that also gas piping clamps part, is installed in the gas measurement device that clamps part, this gas measurement device comprises two ultrasonic transducers, microprocessor, the output of 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, another is the transmission and the reception switch unit of receiver in when metering; 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 ^I, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^I, and obtain the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^I-t_1^I$ The time measurement unit;

The flow rate calculation unit after being used to receive the concurrent-countercurrent propagation time difference Δ t of described time measurement unit output, records the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;D}{c}_2^2\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 1;

In the following formula 1, 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;

The flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of information center to;

Be used to receive the valve driving unit of the long-range closing/Open valve instruction of information center.

4, gas leakage automatic detecting method as claimed in claim 3, it is characterized in that: described flow detector comprises that also gas piping clamps part, is installed in the coal gas measuring and controlling device that clamps part, this coal gas measuring and controlling device comprises two ultrasonic transducers, microprocessor, the output of 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, another is the transmission and the reception switch unit of receiver in when metering;

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 ^I, be transmitted into the adverse current travel-time t that the forward ultrasonic transducer receives from the negative sense ultrasonic transducer ₂ ^I, and obtain the concurrent-countercurrent propagation time difference $\mathrm{\&Delta;t}=t_2^I-t_1^I$ The time measurement unit;

The flow rate calculation unit after being used to receive the concurrent-countercurrent propagation time difference Δ t of described time measurement unit output, records the flow of coal gas with following formula:

$Q=450\mathrm{\&pi;D}{c}_2^2\tan \mathrm{\&theta;}\&times;\mathrm{\&Delta;t}$ Formula 1;

In the following formula 1, 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;

The flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of information center to; Be used to receive the valve driving unit of the long-range closing/Open valve instruction of information center.

5, as claim 3 or 4 described gas leakage automatic detecting methods, it is characterized in that:

Described microprocessor also comprises:

Be used for depositing and be transmitted into the following current travel-time t that the negative sense ultrasonic transducer receives from the forward ultrasonic transducer during coal gas stationary state 1 year every day 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;

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

${\mathrm{\&epsiv;}}_1^d=t_1^d-t_1^I;{\mathrm{\&epsiv;}}_2^d=t_2^d-t_2^I$ Formula 2;

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

$t_1^I=\frac{D/\sin \mathrm{\&theta;}}{c_2+u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 3;

$t_2^I=\frac{D/\sin \mathrm{\&theta;}}{c_2-u\cos \mathrm{\&theta;}}+\mathrm{\&tau;}$ Formula 4;

In the following formula 3 and 4, u is the flow velocity of coal gas in the pipeline, with rice second ^-1Be unit; C2 is 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 5:

$\mathrm{\&tau;}=2\frac{l_1}{c_1}+{\mathrm{\&tau;}}_e$ Formula 5;

In the following formula 5, 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 2 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 information center by remote communication interface.

6, gas leakage automatic detecting method as claimed in claim 5 is characterized in that: described comparative analysis unit also comprises coal gas adverse current judging unit,

If following formula 2 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;

The shut-off valve driver element sends out code to valve-off when the comparative analysis unit judges is adverse current;

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

7, gas leakage automatic detecting method as claimed in claim 6 is characterized in that: described comparative analysis unit also comprises the drift judging unit,

If following formula 2 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 ^INumerical value be stored in storage unit and replace t ₁ ^dInitial value; If ε ₂≠ 0, then with t ₂ ^INumerical value be stored in storage unit and replace t ₂ ^dInitial value.

8, gas leakage automatic detecting method as claimed in claim 7 is characterized in that: the microprocessor of described domestic gas meter also comprises: the flow of the coal gas that the flow rate calculation unit is recorded sends the telecommunication unit of charging center to.

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