CN103016948B - The online leakage detection apparatus of Thermal Power Station's steam-water pipe drain valve - Google Patents

Abstract

The online leakage detection apparatus of a kind of Thermal Power Station's steam-water pipe drain valve, be made up of digital temperature sensor, digital temperature signal collector, 485 telecommunication cables, light cat, optical cable and data handling machine, described digital temperature sensor adopts DS18B20, and several digital temperature sensors that same drain valve downstream drain water piping external circumferential is arranged share a digital temperature signal collection device; Described digital temperature signal collector adopts microprocessor ARM7, the signal that collection comes is passed to data handling machine by data communication circuit and processes; According to data and the variance ratio thereof of drain valve downstream wall surface temperature, the principle of Fuzzy Pattern Recognition is adopted to carry out fuzzy diagnosis to trap leaking grade.The present invention is simple by system, convenient for installation and maintenance, can on-line real time monitoring, and makes judgement promptly and accurately to trap leaking.

Description

The online leakage detection apparatus of Thermal Power Station's steam-water pipe drain valve

Technical field

The present invention relates to a kind of device of hunting leak in real time online for Thermal Power Station's steam-water pipe drain valve, belong to detection technique field.

Background technique

Steam inevitably loses heat in pipeline transmitting procedure, condensation will be started when its temperature is reduced to saturation temperature, form water of condensation and hydrophobic, this part is hydrophobic needs by ad hoc drain water piping exhaust steam pipeline timely, in order to avoid produce the water slug of steam line, cause pipeline and device damage.The water of drain water piping is reclaimed by draining system simultaneously, it also avoid the loss of part working medium and heat.

The steam line of Thermal Power Station is arranged usually the drain water piping of some, and a hydrophobic valve is at least installed on each drain water piping, by the opening and closing of hydrophobic valve, hydrophobic discharge can be controlled.Unit start up period, each hydrophobic valve should be opened, and now can produce a large amount of water of condensation in steam heating coil process, needs to be discharged from steam line in time by hydrophobic pipeline.Terminate once start heating coil process, enter normal working, then hydrophobic valve should be closed, in order to avoid the steam of steam line enters hydrophobic pipeline, causes vapour losses.

The main steam line, reheaing steam pipe, gland steam pipeline, extraction line etc. of thermal power generator is all provided with drain water piping.In addition, on high temperature, the high-pressure water pipeline such as feedwater piping, economizer header, drum emergency blow-off pipe line, boiler periodical blowdown pipeline of boiler, also hydrophobic pipeline can be installed.These unrestrained water lines are all provided with some hydrophobic valves (10).Drain valve is the key equipment on hydrophobic pipeline, and wherein the side of most of valve works under high-temperature high-pressure state.In drain valve switch process, water of condensation, steam frequent impact, burn into wear valve, cause drain valve to be not closed completely, leakage failure often occur.Drain valve is revealed to be divided into and is leaked outside and interior leakage.Leak outside after referring to drain valve fault and outwardly reveal steam (or hot water) from the position such as valve body or connecting part, the external leakage of drain valve judges by sound and phenomenon, and this fault easily finds.Interior leakage refers to that drain valve loses the function stoping carbonated drink, some vapor or the hydrophobic inside from hydrophobic valve is directly passed through, and drains into draining system through drain pipe.The generation of leaking fault in drain valve is comparatively general, and is not easily found.Under normal operating condition of unit, hydrophobic valve leaks, and the steam of the High Temperature High Pressure in steam line or water can be made to bleed drain water piping, and the flow of the steam produced and water and heat loss, reduce the Economy of unit.

In the prior art, conventional drain valve internal leakage inspection method has:

(1) whether shutdown inspection method, namely after compressor emergency shutdown, regularly take drain valve observation internal component apart and break down, determine whether drain valve has interior leakage phenomenon to exist with this.This method operates pretty troublesome, waste plenty of time and manpower, and can only do rough judgement, is difficult to determine for less leakage, and need carry out continuously if produced, the method also cannot perform.

(2) observation mirror method, difference main steam and flash-off steam more difficult, need enough experiences.This method is only applicable to low pressure operating mode, also may lose efficacy because of minute surface fouling simultaneously.

(3) ultrasonic leak detection method, when high pressure steam occurs to produce turbulent flow near leak source when leaking, produces ultrasound simultaneously, and does not have ultrasound generation during drain valve normal discharge condensed water.Can judge whether to leak by specialized equipment detection drain valve place ultrasound data and in conjunction with the Operational Limits of unit and occur.This detection system relates to the multiple ken such as machine, light (laser light location leak source), electricity, sound, relates to acoustic signals conversion treatment etc., system complex.And environmental background noise, also can disturb its accuracy judged.

(4) thermocouple detection method, adopting and measures pipeline wall or Temperature of Working before and after valve, by comparing the change of the forward and backward temperature of valve, judging whether valve exists leakage.For the pipeline of high temperature, high pressure, adopt the method temperature detection element used to need withstand high temperatures environment, consider from security standpoint, its temperature point must install before unit starting, otherwise after unit operation, after in pipe, steam parameter raises, it is installed and used, and there is more restriction.

When said method is used for the on-line checkingi of equipment, also need special device to be digital signal (namely A/D changes) by the analog-signal transitions of measurement, system complex, equipment investment are larger.Consider that the quantity of Thermal Power Station's drain valve is many, space distribution is complicated, and above-mentioned several detecting method exists the problems such as system complex, detection facility investment is comparatively large, energy consumption is higher.In order to overcome the problems referred to above, the present invention propose a kind of system simple, stable, can the One Wire digitizing Thermal Power Station steam-water pipe drain valve leakage detection apparatus of on-line real time monitoring.

Summary of the invention:

The object of the present invention is to provide the device that a kind of system is simple, stable, energy on-line real time monitoring, detection power plant steam-water pipe hydrophobic valve leak.

Problem of the present invention realizes with following technical proposals:

The online leakage detection apparatus of a kind of Thermal Power Station's steam-water pipe drain valve, formation comprises signal picker, data handling machine and is arranged on the digital temperature sensor on drain water piping that detected drain valve is connected, described digital temperature sensor adopts DS18B20, and its signal output part connects the input port of signal picker; Described signal picker adopts micro-chip processor ARM7, and its PORT COM is connected with data handling machine by optical cable.

The online leakage detection apparatus of above-mentioned Thermal Power Station's steam-water pipe drain valve, the digital temperature sensor corresponding with each detected drain valve all arranges multiple, they are all arranged on the downstream drain water piping of detected drain valve, and around the axis arranged of drain water piping, all digital temperature sensors corresponding to one or more detected drain valve are connected by the signal input port of bus with same signal picker.

The online leakage detection apparatus of above-mentioned Thermal Power Station's steam-water pipe drain valve, when drain water piping adopts single thermal insulation layer outward, digital temperature sensor is arranged in single thermal insulation layer, and its position is to the distance of drain water piping axis, and namely digital temperature sensor installation radius r calculates according to the following formula:

$r=r_1{\left(\frac{r_2}{r_1}\right)}^{\frac{T-T_1}{T_2-T_1}},$

Wherein, r ₁for drain pipe exterior radius; r ₂for thermal insulation layer exterior radius; T ₁for drain pipe outside wall temperature; T ₂for thermal insulation layer outside wall temperature; T is the maximum permission thermometric value of digital temperature sensor, is not more than 120 DEG C;

When drain water piping adopts two thermal insulation layer outward, if two thermal insulation layer separating surface temperature is greater than the maximum permission thermometric value of digital temperature sensor, then digital temperature sensor is arranged in external thermal insulation; If two thermal insulation layer separating surface temperature is less than the maximum permission thermometric value of digital temperature sensor, then digital temperature sensor is arranged in inner thermal insulating layer.

The online leakage detection apparatus of above-mentioned Thermal Power Station's steam-water pipe drain valve, gathers the measurement signal of digital temperature sensor, according to these Temperature numerical and variance ratio thereof, whether can there is leakages to hydrophobic valve, leakiness situation carries out analysis judgement;

Described trap leaking judges to carry out as follows:

Described digital temperature sensor is arranged on the drain water piping in downstream after drain valve to be measured, wherein,

$t=\frac{1}{n}\underset{i=1}{\overset{n}{\Σ}}{t}_i,$

If: and: Δ t=t-t _a> δ ₂,

Then trap leaking can be judged;

In formula:

T---hydrophobic tube wall average temperature value;

T _i---the measured value of i-th digital temperature sensor;

The number of n---digital temperature sensor;

τ---the time;

T _a---be ambient temperature or thermal insulation layer hull-skin temperature;

δ ₁, δ ₂, δ ₃---be the alarm limits of user's setting, can according to fluid properties, the setting of pipeline configuration situation in drain water piping; General: δ ₁>0.01-0.5 DEG C/s, δ ₃>0.01-0.5 DEG C/s, δ ₂gather on the temperature difference basis of calculating in No leakage situation, increase 3-15 DEG C.

With Δ t, three parameters as the sign parameter of trap leaking fault, and in conjunction with the principle of Fuzzy Pattern Recognition, judge trap leaking degree further; Concrete steps are: first by the amplitude of variation of each sign parameter, be converted to the fuzzy expression of sign parameter, represent four intervals of sign Parameters variation, represent the large and small degree of the amplitude of variation of each sign parameter respectively with 1,0.5,0.25,0, as follows:

$z_1=\left\{\begin{array}{cc}1& \frac{dt}{d\mathrm{\&tau;}}\&GreaterEqual;a_1\\ 0.5& b_1\&le;\frac{dt}{d\mathrm{\&tau;}}<a_1\\ 0.25& c_1\&le;\frac{dt}{d\mathrm{\&tau;}}<b_1\\ 0& \frac{dt}{d\mathrm{\&tau;}}<c_1\end{array}\right.,z_2=\left\{\begin{array}{cc}1& \mathrm{\&Delta;}t\&GreaterEqual;a_2\\ 0.5& b_2\&le;\mathrm{\&Delta;}t<a_2\\ 0.25& c_2\&le;\mathrm{\&Delta;}t<b_2\\ 0& \mathrm{\&Delta;}t<c_2\end{array}\right.,z_3=\left\{\begin{array}{cc}1& \frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}\&GreaterEqual;a_3\\ 0.5& b_3\&le;\frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<a_3\\ 0.25& c_3\&le;\frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<b_3\\ 0& \frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<c_3\end{array}\right.,$

Z ₁---sign parameter corresponding failure symptom value;

Z ₂---the failure symptom value that sign parameter Δ t is corresponding;

Z ₃---sign parameter corresponding failure symptom value;

A ₁, a ₂, a ₃---the limit value that sign parameter sharply raises, determine according to fluid properties in monitored drain valve;

B ₁, b ₂, b ₃---the limit value that sign parameter slowly raises, determine according to fluid properties in monitored drain valve;

C ₁, c ₂, c ₃---the limit value that sign parameter slightly raises, determine according to fluid properties in monitored drain valve;

The typical fault characteristic vector building the fuzzy diagnosis of trap leaking degree is as follows:

u ₁＝(z ₁₁,z ₁₂,z ₁₃)＝(1,1,1)；

u ₂＝(z ₂₁,z ₂₂,z ₂₃)＝(0.5,0.5,0.5)；

u ₃＝(z ₃₁,z ₃₂,z ₃₃)＝(0.25,0.25,0.25)；

u ₄＝(z ₄₁,z ₄₂,z ₄₃)＝(0,0,0)

Wherein, u ₁, u ₂, u ₃, u ₄corresponding serious leak, moderate leakage, minor leakage and No leakage four kinds of typicalnesses respectively;

According to the temperature data gathered, the characteristic vector that arrangement obtains under current working is u _x=(z ₁, z ₂, z ₃), set up its fuzzy membership functions, calculate:

$S_{u_i}\left(u_x\right)={\&lsqb;1-\frac{d_i(u_x,u_i)}{D}\&rsqb;}^2,i=1,2,3,4,$

$d_i(u_x,u_i)=\frac{|z_1-z_{i1}|+|z_2-z_{i2}|+|z_3-z_{i3}|}{z_{i1}+z_{i2}+z_{i3}},i=1,2,3,4,$

D＝max[d _i(u _x,u _i)]，i＝1,2,3,4，

According to maximum membership grade principle, obtain:

$S_{u_i}\left(u_x\right)=max\left(S_{u_1}\right(u_x),S_{u_2}\left(u_x\right),S_{u_3}\left(u_x\right),S_{u_i}\left(u_x\right)),$

Namely which state in the running state that identifiable design drain valve is current and four kinds of typicalnesses is close, and then makes the judgement of leakiness.

Digital temperature signal sensor is directly arranged in the thermal insulation layer of the drain water piping in drain valve downstream by the present invention, is connected between each sensor by a bus, and system is simple, convenient for installation and maintenance, investment is less.This device can on-line real time monitoring, can make judgement promptly and accurately to trap leaking.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the invention will be further described.

Fig. 1 is System's composition schematic diagram of the present invention;

Fig. 2 is the scheme of installation of drain water piping cross section, digital temperature sensor;

Fig. 3, Fig. 4-a, Fig. 4-b are the position estimation schematic diagram of digital temperature sensor in drain water piping radial direction;

Fig. 5 is the mounting point pipeline local section schematic diagram of digital temperature sensor;

Fig. 6 is collector schematic diagram.

In figure, each list of reference numerals is: 1, digital temperature sensor; 2, bus; 3, collector; 4,485 telecommunication cables; 5, light cat; 6, optical cable; 7, data handling machine; 8, information system of power plants (MIS or SIS) server; 9, steam (hot water) pipeline; 10, drain valve; 11, drain water piping; 12, drain pipe tube wall; 13, thermal insulation layer; 14, thermal insulation layer outer wall.

In literary composition, symbol inventory used is: r ₁, drain pipe radius; r ₂, thermal insulation layer radius; r ₃, two thermal insulation layer time thermal insulation layer separating surface radius; R, digital temperature sensor install radius; T ₁, drain pipe wall temperature; T ₂thermal insulation layer outside wall temperature; T ₃, two thermal insulation layer separating surface temperature; The temperature at T, digital temperature sensor place; Δ r, digital temperature sensor are apart from the distance of thermal insulation layer outer wall; λ ₁, internal layer thermal insulating material thermal conductivity; λ ₂, outer thermal insulating material thermal conductivity; The length of l, drain pipe axis.

Embodiment

The present invention relates to Thermal Power Station's drain valve leakage detection apparatus, primarily of compositions such as digital temperature sensor, bus, collector, 485 telecommunication cables, light cat, optical cable, data handling machines.Data handling machine is located at control room, for collecting temperature data, carry out data logging and process, leak judge to process, warning sign output etc.

When drain valve occurs to leak, ducted high-temperature steam, water can make the drain pipe wall temperature of valve downstream raise, the digital temperature sensor be arranged in outside tube wall can record its temperature variation, several digital temperature sensors can be evenly arranged in the drain water piping circumference at drain valve place to be checked, ask the mean value of temperature variation, improve measuring accuracy.The digital temperature sensor at same drain valve place is connected to collector by a bus parallel connection.

Passed to data handling machine processed by light cat, optical cable after collector collects signal.

Digital temperature sensor adopts DS18B20, and it is the one-line digital temperature sensor that DALLAS company produces, and temperature-measuring range is-55 DEG C ~+125 DEG C, is programmed for 9 ~ 12 A/D conversion accuracies, and the most I of thermometric resolution reaches 0.0625 DEG C.DS18B20 is applicable to remote multi-point temp detection system.

On the pipeline such as main steam line, reheaing steam pipe, gland steam pipeline, pump-line, feed water preheater emergency blowoff pipeline of thermal power generator, be all provided with hydrophobic pipeline and some hydrophobic valves.Visible, the steam parameter at different drain valve place is different, and even difference is very large, and the highest vapor (steam) temperature can more than 540 DEG C, far above the temperature-measuring range of digital temperature sensor DS18B20.For ensureing the safe and stable operation of this power plant's drain valve leakage detection apparatus, digital temperature sensor must be arranged in rational position, such that temperature value is herein the highest is no more than 120 DEG C.As Fig. 4, according to heat transfer principle, the position of digital temperature sensor in pipeline radial direction can be estimated according to the following formula:

$t=t_1+\frac{t_2-t_1}{\ln (r_2/r_1)}\ln (r/r_1),$

Arrange: $r=r_1{\left(\frac{r_2}{r_1}\right)}^{\frac{T-T_1}{T_2-T_1}},$

The then distance of digital temperature sensor distance thermal insulation layer outer wall in pipeline radial direction: Δ r=r ₂-r

When drain water piping adopts two thermal insulation layer outward, the position of digital temperature sensor in pipeline radial direction can be estimated according to following formula:

$\frac{2{\mathrm{\&pi;\&lambda;}}_{1}l(t_1-t)}{\ln (r/r_1)}=\frac{2{\mathrm{\&pi;\&lambda;}}_{2}l(t-t_2)}{\ln (r_2/r)},$

First establish r=r ₃, calculate t ₃, as t > t ₃time, digital temperature sensor mounting point is, Δ r=r ₂-r; As t < t ₃time, digital temperature sensor mounting point is, Δ r=r ₂-r, wherein, r ₁, drain pipe radius; r ₂, thermal insulation layer radius; r ₃, two thermal insulation layer time thermal insulation layer separating surface radius; R, digital temperature sensor install radius; T ₁, drain pipe wall temperature; T ₂thermal insulation layer outside wall temperature; T ₃, two thermal insulation layer separating surface temperature; The temperature at T, digital temperature sensor place; λ ₁, internal layer thermal insulating material thermal conductivity; λ ₂, outer thermal insulating material thermal conductivity; L, drain pipe external thermal insulation are in the length of drain pipe axis; T is the maximum permission thermometric value of digital temperature sensor, and value is less than 120 DEG C.

Gather the measurement signal of these digital temperature sensors, according to these Temperature numerical and variance ratio thereof, whether can there is the situations such as leakage, leakiness to hydrophobic valve and carry out analysis judgement.

Described trap leaking judges to carry out as follows:

Described digital temperature sensor is arranged on the drain water piping after drain valve to be measured, wherein,

$t=\frac{1}{n}\underset{i=1}{\overset{n}{\&Sigma;}}{t}_i,$

If: and: Δ t=t-t _a> δ ₂,

Then trap leaking can be judged;

In formula:

T---hydrophobic tube wall average temperature value;

T _i---the measured value of i-th digital temperature sensor;

N---the number of digital temperature sensor on section;

τ---the time;

T _a---be ambient temperature or thermal insulation layer hull-skin temperature;

δ ₁, δ ₂, δ ₃---be the alarm limits of user's setting, can according to fluid properties, the setting of pipeline configuration situation in drain water piping.General: δ ₁>0.01-0.5 DEG C/s, δ ₃>0.01-0.5 DEG C/s, δ ₂gather on the temperature difference basis of calculating in No leakage situation, increase 3-15 DEG C.

With Δ t, three parameters as the sign parameter of trap leaking fault, and in conjunction with the principle of Fuzzy Pattern Recognition, judge trap leaking degree further; Concrete steps are: first by the amplitude of variation of each sign parameter, be converted to the fuzzy expression of sign parameter, represent four intervals of sign Parameters variation, represent the large and small degree of the amplitude of variation of each sign parameter respectively with 1,0.5,0.25,0, as follows:

$z_1=\left\{\begin{array}{cc}1& \frac{dt}{d\mathrm{\&tau;}}\&GreaterEqual;a_1\\ 0.5& b_1\&le;\frac{dt}{d\mathrm{\&tau;}}<a_1\\ 0.25& c_1\&le;\frac{dt}{d\mathrm{\&tau;}}<b_1\\ 0& \frac{dt}{d\mathrm{\&tau;}}<c_1\end{array}\right.,z_2=\left\{\begin{array}{cc}1& \mathrm{\&Delta;}t\&GreaterEqual;a_2\\ 0.5& b_2\&le;\mathrm{\&Delta;}t<a_2\\ 0.25& c_2\&le;\mathrm{\&Delta;}t<b_2\\ 0& \mathrm{\&Delta;}t<c_2\end{array}\right.,z_3=\left\{\begin{array}{cc}1& \frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}\&GreaterEqual;a_3\\ 0.5& b_3\&le;\frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<a_3\\ 0.25& c_3\&le;\frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<b_3\\ 0& \frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<c_3\end{array}\right.,$

Z ₁---sign parameter corresponding failure symptom value;

Z ₂---the failure symptom value that sign parameter Δ t is corresponding;

Z ₃---sign parameter corresponding failure symptom value;

A ₁, a ₂, a ₃---the limit value that sign parameter sharply raises, determine according to fluid properties in monitored drain valve;

B ₁, b ₂, b ₃---the limit value that sign parameter slowly raises, determine according to fluid properties in monitored drain valve;

C ₁, c ₂, c ₃---the limit value that sign parameter slightly raises, determine according to fluid properties in monitored drain valve;

The typical fault characteristic vector building the fuzzy diagnosis of trap leaking degree is as follows:

u ₁＝(z ₁₁,z ₁₂,z ₁₃)＝(1,1,1)；

u ₂＝(z ₂₁,z ₂₂,z ₂₃)＝(0.5,0.5,0.5)；

u ₃＝(z ₃₁,z ₃₂,z ₃₃)＝(0.25,0.25,0.25)；

u ₄＝(z ₄₁,z ₄₂,z ₄₃)＝(0,0,0)

Wherein, u ₁corresponding serious leak, u ₂corresponding moderate is leaked, u ₃corresponding minor leakage, u ₄corresponding No leakage four kinds of typicalnesses;

According to the temperature data gathered, the characteristic vector that arrangement obtains under current working is u _x=(z ₁, z ₂, z ₃), set up its fuzzy membership functions, calculate:

$S_{u_i}\left(u_x\right)={\&lsqb;1-\frac{d_i(u_x,u_i)}{D}\&rsqb;}^2,i=1,2,3,4,$

$d_i(u_x,u_i)=\frac{|z_1-z_{i1}|+|z_2-z_{i2}|+|z_3-z_{i3}|}{z_{i1}+z_{i2}+z_{i3}},i=1,2,3,4,$

D＝max[d _i(u _x,u _i)]，i＝1,2,3,4，

According to maximum membership grade principle, obtain:

$S_{u_i}\left(u_x\right)=max\left(S_{u_1}\right(u_x),S_{u_2}\left(u_x\right),S_{u_3}\left(u_x\right),S_{u_4}\left(u_x\right)),$

Namely which state in the running state that identifiable design drain valve is current and four kinds of typicalnesses is close, and then makes the judgement of leakiness.

According to the mounting point of on-site actual situations determination collector, determine that the digital temperature sensor at the drain valve place of some quantity shares a signal picker simultaneously.Such as: in Fig. 1, illustrate that some digital temperature sensors at two contiguous hydrophobic valve places share a collector.

For certain 300MW station boiler, its design vapor pressure is 17.5MPa, and temperature is 540 DEG C.Superheater outlet leg arranges a road hydrophobic pipeline, and two drain valves are housed, and drain pipe specification is φ 42 × 5.5, is the glass wool insulation of 22mm, the tube wall in hydrophobic valve downstream installs digital temperature sensor in the outer applied thickness of drain pipe.Through calculating, digital temperature sensor is arranged in the thermal insulation layer at distance drain pipe outer wall surface 18mm place, and under can ensureing various operating mode, its temperature is no more than 120 DEG C.Ambient temperature is 30 DEG C.Find through simulation calculation, there is interior leakage in drain valve, if when leakage flow is 0.084kg/s, experience after 5 minutes, relevant parameter tends towards stability by closing tight state.In one period of transient time after fault occurs, the wall surface temperature measured by digital temperature sensor, its temperature rise rate δ ₁, difference variation rate δ ₃, and with the difference δ of ambient temperature ₂nonlinear over time, wherein δ ₁, δ ₃changing Pattern consistent, excursion is 0.01-1.36 DEG C/s.The wall surface temperature measured by digital temperature sensor and the difference δ of ambient temperature ₂also be increased to 66.2 DEG C by 9.7 DEG C, temperature approach adds 56.5 DEG C.Therefore, according to the temperature that digital temperature sensor gathers, by analyzing wall temperature rise rate δ ₁, difference variation rate δ ₃, and with the difference δ of ambient temperature ₂changing Pattern, can identify the leakage failure of hydrophobic valve in time and judge.

The present invention can also have other mode of executions, and all employings are equal to the technological scheme of replacement or equivalent transformation formation, all should drop within protection scope of the present invention.

Claims (2)

1. the online leakage detection apparatus of Thermal Power Station's steam-water pipe drain valve, it is characterized in that, it comprises signal picker (3), data handling machine (7) and is arranged on the digital temperature sensor (1) on drain water piping (11) that detected drain valve (10) is connected, described digital temperature sensor (1) adopts DS18B20, and its signal output part connects the input port of signal picker (3); Described signal picker (3) adopts micro-chip processor ARM7, and its PORT COM is connected with data handling machine (7) by optical cable (6);

The digital temperature sensor (1) corresponding with each detected drain valve (10) all arranges multiple, they are all arranged on the downstream drain water piping of detected drain valve (10), and along the axis arranged of drain water piping (11), all digital temperature sensors (1) corresponding to one or more detected drain valve (10) are connected by the signal input port of bus with same signal picker (3);

When drain water piping (11) adopts single thermal insulation layer (13) outward, digital temperature sensor (1) is arranged in single thermal insulation layer (13), its position is to the distance of drain water piping (11) axis, and namely digital temperature sensor installation radius r calculates according to the following formula:

$r=r_1{\left(\frac{r_2}{r_1}\right)}^{\frac{T-T_1}{T_2-T_1}},$

Wherein, r ₁for drain pipe exterior radius; r ₂for thermal insulation layer exterior radius; T ₁for drain pipe outside wall temperature; T ₂for thermal insulation layer outside wall temperature; T is the maximum permission thermometric value of digital temperature sensor;

When drain water piping (11) adopts two thermal insulation layer outward, if two thermal insulation layer separating surface temperature is greater than the maximum permission thermometric value of digital temperature sensor (1), then digital temperature sensor (1) is arranged in external thermal insulation (15); If two thermal insulation layer separating surface temperature is less than the maximum permission thermometric value of digital temperature sensor (1), then digital temperature sensor (1) is arranged in inner thermal insulating layer (14).

2. the online leakage detection apparatus of Thermal Power Station's steam-water pipe drain valve according to claim 1, it is characterized in that, gather the measurement signal of digital temperature sensor, according to these Temperature numerical and variance ratio thereof, whether can there is to hydrophobic valve leakages, leakiness situation carries out analysis judgement;

Described trap leaking judges to carry out as follows:

Described digital temperature sensor is arranged on the drain water piping after drain valve to be measured, wherein,

$t=\frac{1}{n}\underset{i=1}{\overset{n}{\&Sigma;}}{t}_i,$

If: and: Δ t=t-t _a> δ ₂,

Then trap leaking can be judged;

In formula:

T---hydrophobic tube wall average temperature value;

T _i---the measured value of i-th digital temperature sensor;

N---the number of digital temperature sensor on section;

τ---the time;

T _a---be ambient temperature or thermal insulation layer hull-skin temperature;

δ ₁, δ ₂, δ ₃---be the alarm limits of user's setting, can according to fluid properties, the setting of pipeline configuration situation in drain water piping; Wherein: δ ₁> 0.01 DEG C/s, δ ₃> 0.01 DEG C/s, δ ₂gather on the temperature difference basis of calculating in No leakage situation, increase 3-15 DEG C;

With Δ t, three parameters as the sign parameter of trap leaking fault, and in conjunction with the principle of Fuzzy Pattern Recognition, judge trap leaking degree further; Concrete steps are: first by the amplitude of variation of each sign parameter, be converted to the fuzzy expression of sign parameter, represent four intervals of sign Parameters variation, represent the large and small degree of the amplitude of variation of each sign parameter respectively with 1,0.5,0.25,0, as follows:

$z_1=\left\{\begin{array}{cc}1& \frac{dt}{d\mathrm{\&tau;}}\&GreaterEqual;a_1\\ 0.5& b_1\&le;\frac{dt}{d\mathrm{\&tau;}}<a_1\\ 0.25& c_1\&le;\frac{dt}{d\mathrm{\&tau;}}<b_1\\ 0& \frac{dt}{d\mathrm{\&tau;}}<c_1\end{array}\right.,z_2=\{\begin{array}{cc}1& \mathrm{\&Delta;}t\&GreaterEqual;a_2\\ 0.5& b_2\&le;\mathrm{\&Delta;}t<a_2\\ 0.25& c_2\&le;\mathrm{\&Delta;}t<b_2\\ 0& \mathrm{\&Delta;}t<c_2\end{array},z_3=\left\{\begin{array}{cc}1& \frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}\&GreaterEqual;a_3\\ 0.5& b_3\&le;\frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<a_3\\ 0.25& c_3\&le;\frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<b_3\\ 0& \frac{d\mathrm{\&Delta;}t}{d\mathrm{\&tau;}}<c_3\end{array}\right.,$

Z ₁---sign parameter corresponding failure symptom value;

Z ₂---the failure symptom value that sign parameter Δ t is corresponding;

Z ₃---sign parameter corresponding failure symptom value;

A ₁, a ₂, a ₃---the limit value that sign parameter sharply raises, determine according to fluid properties in monitored drain valve;

B ₁, b ₂, b ₃---the limit value that sign parameter slowly raises, determine according to fluid properties in monitored drain valve;

C ₁, c ₂, c ₃---the limit value that sign parameter slightly raises, determine according to fluid properties in monitored drain valve;

The typical fault characteristic vector building the fuzzy diagnosis of trap leaking degree is as follows:

u ₁＝(z ₁₁,z ₁₂,z ₁₃)＝(1,1,1)；

u ₂＝(z ₂₁,z ₂₂,z ₂₃)＝(0.5,0.5,0.5)；

u ₃＝(z ₃₁,z ₃₂,z ₃₃)＝(0.25,0.25,0.25)；

u ₄＝(z ₄₁,z ₄₂,z ₄₃)＝(0,0,0)

Wherein, u ₁, u ₂, u ₃, u ₄corresponding serious leak, moderate leakage, minor leakage and No leakage four kinds of typicalnesses respectively;

According to the temperature data gathered, the characteristic vector that arrangement obtains under current working is u _x=(z ₁, z ₂, z ₃), set up its fuzzy membership functions, calculate:

$S_{u_i}\left(u_x\right)={\&lsqb;1-\frac{d_i(u_x,u_i)}{D}\&rsqb;}^2,i=1,2,3,4$

$d_i(u_x,u_i)=\frac{\left|z_1-z_{i1}\right|+\left|z_2-z_{i2}\right|+\left|z_3-z_{i3}\right|}{z_{i1}+z_{i2}+z_{i3}},i=1,2,3,4,$

D＝max[d _i(u _x,u _i)]，i＝1,2,3,4，

According to maximum membership grade principle, obtain:

$S_{u_i}\left(u_x\right)=\max \left(S_{u_1}\right(u_x),S_{u_2}(u_x),S_{u_3}(u_x),S_{u_4}(u_x\left)\right),$

Namely which state in the running state that identifiable design drain valve is current and four kinds of typicalnesses is close, and then makes the judgement of leakiness.