CN103016948A - Online leak detection device for steam trap of steaming-water pipeline of thermal power plant - Google Patents

Abstract

Translated fromChinese

一种热力发电厂汽水管道疏水阀在线检漏装置，由数字温度传感器、数字温度信号采集器、485通信电缆、光猫、光缆和数据处理计算机组成，所述数字温度传感器采用DS18B20，同一疏水阀下游疏水管道外侧周向上布置的若干个数字温度传感器共用一个数字温度信号采集器；所述数字温度信号采集器采用微处理器ARM7，将采集来的信号通过数据通讯线路传递给数据处理计算机进行处理；根据疏水阀下游壁面温度的数据及其变化率，采用模糊模式识别的原理对疏水阀泄漏等级进行模糊识别。本发明将系统简单、安装维护方便，可在线实时监测，并对疏水阀泄漏做出及时准确的判断。

An online leak detection device for steam-water pipeline traps in thermal power plants, composed of digital temperature sensors, digital temperature signal collectors, 485 communication cables, optical modems, optical cables, and data processing computers. The digital temperature sensors use DS18B20, and the same traps A number of digital temperature sensors arranged circumferentially on the outer side of the downstream drainage pipeline share a digital temperature signal collector; the digital temperature signal collector adopts a microprocessor ARM7, and transmits the collected signal to a data processing computer for processing through a data communication line ;According to the temperature data of the wall surface downstream of the trap and its rate of change, the principle of fuzzy pattern recognition is used to fuzzy identify the leakage level of the trap. The invention has the advantages of simple system, convenient installation and maintenance, online real-time monitoring, and timely and accurate judgment on the leakage of the steam trap.

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 for the online in real time device of leak detection of Thermal Power Station's steam-water pipe drain valve, genus detection technique field.

Background technique

Steam is wanted loses heat inevitably in the pipeline transmission process, when being reduced to saturation temperature, its temperature will begin to condense, form water of condensation namely hydrophobic, this part hydrophobic needs passes through timely exhaust steam pipeline of ad hoc drain water piping, in order to avoid produce the water slug of steam line, cause pipeline and device damage.The water of drain water piping reclaims by draining system simultaneously, has also avoided the loss of part working medium and heat.

Usually arrange the drain water piping of some on the steam line of Thermal Power Station, and a hydrophobic valve is installed on each drain water piping at least, by the opening and closing of hydrophobic valve, can control hydrophobic discharging.Unit the start up period, each hydrophobic valve should be opened, can produce a large amount of water of condensation in steam heating coil process this moment, needs in time to discharge from steam line by hydrophobic pipeline.Finish in case start the 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.

All be provided with drain water piping on the main steam line of thermal power generator, reheaing steam pipe, gland steam pipeline, the extraction line etc.In addition, on high temperature, the high-pressure water pipelines such as the feedwater piping of boiler, economizer header, drum emergency blow-off pipe line, boiler periodical blowdown pipeline, also hydrophobic pipeline can be installed.Some hydrophobic valves (10) all are installed on these unrestrained water lines.Drain valve is the key equipment on the hydrophobic pipeline, and wherein a side of most of valve is worked under high-temperature high-pressure state.In drain valve switch process, water of condensation, steam frequent impact, burn into wearing and tearing valve cause that drain valve is not closed completely, leakage failure often occurs.Drain valve is revealed to be divided into and is leaked outside and interior leakage.Leaking outside refers to that outside boundary reveals steam (or hot water) from positions such as valve body or connecting parts after the drain valve fault, and the outside of drain valve is revealed and can be judged by sound and phenomenon, and this fault is easily found.Interior leakage refers to that drain valve lost the function that stops carbonated drink, part steam or hydrophobic internal direct from hydrophobic valve was connected, and drained into draining system through drain pipe.The generation of leaking fault in the drain valve is more general, and is difficult for being found.Under the normal operating condition of unit, hydrophobic valve leaks, and meeting is drain water piping so that the steam of the High Temperature High Pressure in the steam line or water bleed, and the steam that produces and flow and the heat loss of water, the Economy of reduction unit.

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

Whether (1) shutdown inspection method namely behind compressor emergency shutdown, is regularly taken drain valve observation internal component apart and is broken down, and determines with this whether drain valve has interior leakage phenomenon to exist.This method operates pretty troublesome, waste plenty of time and manpower, and can only do rough judgement, and be difficult to determine for less leakage, need carry out continuously if produce, the method also can't be carried out.

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

(3) ultrasonic leak detection method can produce turbulent flow near leak source when high pressure steam occur to leak, produce simultaneously ultrasound, and drain valve does not have the ultrasound generation when normally discharging condensed water.Detect drain valve place's ultrasound data and can judge whether to leak in conjunction with the Operational Limits of unit by specialized equipment and occur.This detection system relates to the multiple kens 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 the accuracy of its judgement.

(4) thermocouple detection method adopts and measures valve front and back pipeline wall or Temperature of Working, by the relatively variation of the forward and backward temperature of valve, judges whether valve exists leakage.For the pipeline of high temperature, high pressure, adopt the used temperature detection element of the method to need the withstand high temperatures environment, consider from security standpoint, its temperature point must install before unit starting, otherwise behind the unit operation, after steam parameter raise in the pipe, it was installed and used and then has more restriction.

When said method was used for online detections of equipment, also needing special device was digital signal (being that A/D changes) with the analog-signal transitions of measuring, and system complex, equipment investment are larger.The quantity of considering Thermal Power Station's drain valve is many, and space distribution is complicated, and there are the problems such as system complex, the detection facility investment is large, energy consumption is higher in above-mentioned several detecting methods.In order to overcome the problems referred to above, the present invention proposes that a kind of system is simple, stable, line digitizing processed Thermal Power Station steam-water pipe drain valve leakage detection apparatus that can on-line real time monitoring.

Summary of the invention

The object of the present invention is to provide a kind of system simple, stable, can on-line real time monitoring, detect the device that power plant's steam-water pipe hydrophobic valve leaks.

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, comprise signal picker, data handling machine in the formation and be connected digital temperature sensor on the drain water piping that detected drain valve connects, 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 a plurality of, they all are installed on the downstream drain water piping of detected drain valve, and around the axis arranged of drain water piping, corresponding all digital temperature sensors of one or more detected drain valves are connected with the signal input port of same signal picker by bus.

The online leakage detection apparatus of above-mentioned Thermal Power Station's steam-water pipe drain valve, when adopting single thermal insulation layer outside the drain water piping, digital temperature sensor is installed in single thermal insulation layer, and its position is to the distance of drain water piping axis, and namely digital temperature sensor is installed radiusrBe calculated according to the following formula:

，

Wherein, r₁Be the drain pipe exterior radius; r₂Be the thermal insulation layer exterior radius; t₁Be the drain pipe outside wall temperature; t₂Be the thermal insulation layer outside wall temperature;tMaximum permission thermometric value for digital temperature sensor is not more than 120 ℃;

When adopting two thermal insulation layer outside the drain water piping, if two thermal insulation layer separating surface temperature allows the thermometric value greater than the maximum of digital temperature sensor, then digital temperature sensor is installed in the external thermal insulation; If two thermal insulation layer separating surface temperature allow the thermometric value less than the maximum of digital temperature sensor, then digital temperature sensor is installed in the inner thermal insulating layer.

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

Described trap leaking judgement is carried out as follows:

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

，

If:

And:

,

,

Then can judge trap leaking;

In the formula:

---hydrophobic tube wall average temperature value;

---theiThe measured value of individual digital temperature sensor;

---the number of digital temperature sensor;

---the time;

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

---for the warning limit value that the user sets, can set according to fluid properties, pipeline configuration situation in the drain water piping; Generally:0.01-0.5 ℃/s,

0.01-0.5 ℃/s,

Without gathering on the temperature difference basis of calculating under the leakage situation, increase 3-15 ℃.

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

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

，

，，

---the sign parameterCorresponding failure symptom value;

---the sign parameter

Corresponding failure symptom value;

---the sign parameter

Corresponding failure symptom value;

---the limit value that the sign parameter sharply raises, determine according to fluid properties in the drain valve of monitoring;

---the limit value that the sign parameter slowly raises, determine according to fluid properties in the drain valve of monitoring;

---the slight limit value that raises of sign parameter, determine according to fluid properties in the drain valve of monitoring;

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

Wherein,

,

,,Respectively correspondingly seriously leak, moderate is leaked, slightly leak and without leaking four kinds of typicalnesses;

According to the temperature data that gathers, the characteristic vector that arrangement obtains under the current working isu_x=

, set up its fuzzy membership functions, calculate:

，i=1,2,3,4，

，i=1,2,3,4，

，i=1,2,3,4，

According to maximum membership grade principle, obtain:

，

Which state that can identify in the current running state of drain valve and the four kinds of typicalnesses approaches, and then makes the judgement of leakiness.

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

Description of drawings

The invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is that system of the present invention consists of schematic diagram;

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 that digital temperature sensor is at drain water piping position estimation schematic diagram radially;

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

Fig. 6 is the collector electrical schematic diagram.

Each list of reference numerals is among the figure: 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.

Used symbol inventory is in the literary composition: r₁, the drain pipe radius; r₂, the thermal insulation layer radius; r₃, thermal insulation layer separating surface radius during two thermal insulation layer; R, digital temperature sensor are installed radius; t₁, the drain pipe wall temperature; t₂The thermal insulation layer outside wall temperature; t₃, 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;, the internal layer thermal insulating material thermal conductivity;, outer thermal insulating material thermal conductivity;, the axial length of drain pipe.

Embodiment

The present invention relates to Thermal Power Station's drain valve leakage detection apparatus, mainly formed by digital temperature sensor, bus, collector, 485 telecommunication cables, light cat, optical cable, data handling machine etc.Data handling machine is located at the control room, is used for collecting temperature data, carries out data logging and processing, leaks and judge processing, 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 that is arranged in the tube wall outside can record its temperature variation, can circumferentially be evenly arranged several digital temperature sensors at the drain water piping at drain valve to be checked place, ask the mean value of temperature variation, improve measuring accuracy.The digital temperature sensor at same drain valve place is connected in collector by a bus parallel connection.

Collector passes to data handling machine with it and processes by light cat, optical cable after collecting 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 ℃～+ 125 ℃, is programmed for 9～12 A/D conversion accuracies, and the I of thermometric resolution reaches 0.0625 ℃.DS18B20 is applicable to remote multi-point temp detection system.

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

，

Put in order:

,

Then digital temperature sensor directly makes progress apart from the distance of thermal insulation layer outer wall at pipeline:

When adopting two thermal insulation layer outside the drain water piping, can estimate the position that digital temperature sensor directly makes progress at pipeline according to following formula:

，

Establish first

, calculate

, whenThe time, the digital temperature sensor mounting point is,

,

When

The time, the digital temperature sensor mounting point is,

,

, wherein, r₁, the drain pipe radius; r₂, the thermal insulation layer radius; r₃, thermal insulation layer separating surface radius during two thermal insulation layer; R, digital temperature sensor are installed radius; t₁, the drain pipe wall temperature; t₂The thermal insulation layer outside wall temperature; t₃, two thermal insulation layer separating surface temperature; The temperature at t, digital temperature sensor place;, the internal layer thermal insulating material thermal conductivity;

, outer thermal insulating material thermal conductivity;

, the drain pipe external thermal insulation is in the axial length of drain pipe;tBe the maximum permission thermometric value of digital temperature sensor, value is less than 120 ℃.

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

Described trap leaking judgement is carried out as follows:

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

，

If:

And:

,

,

Then can judge trap leaking;

In the formula:

---hydrophobic tube wall average temperature value;

---theiThe measured value of individual digital temperature sensor;

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

---the time;

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

---for the warning limit value that the user sets, can set according to fluid properties, pipeline configuration situation in the drain water piping.Generally:

0.01-0.5 ℃/s,

0.01-0.5 ℃/s,

Without gathering on the temperature difference basis of calculating under the leakage situation, increase 3-15 ℃.

With

,

,

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

，

，

，

---the sign parameterCorresponding failure symptom value;

---the sign parameter

Corresponding failure symptom value;

---the sign parameterCorresponding failure symptom value;

---the limit value that the sign parameter sharply raises, determine according to fluid properties in the drain valve of monitoring;

---the limit value that the sign parameter slowly raises, determine according to fluid properties in the drain valve of monitoring;

---the slight limit value that raises of sign parameter, determine according to fluid properties in the drain valve of monitoring;

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

Wherein,

Corresponding serious the leakage,

Corresponding moderate is leaked,

Corresponding slight the leakage,

Corresponding to leaking four kinds of typicalnesses;

According to the temperature data that gathers, the characteristic vector that arrangement obtains under the current working isu_x=

, set up its fuzzy membership functions, calculate:

，i=1,2,3,4，

，i=1,2,3,4，

，i=1,2,3,4，

According to maximum membership grade principle, obtain:

，

Which state that can identify in the current running state of drain valve and the four kinds of typicalnesses approaches, and then makes the judgement of leakiness.

Determine the mounting point of collector according to on-site actual situations, determine that simultaneously the digital temperature sensor at the drain valve place of some quantity shares a signal picker.For example: some digital temperature sensors at two adjacent drain valve places of signal share a collector among Fig. 1.

Take certain 300MW station boiler as example, its design vapor pressure is 17.5MPa, and temperature is 540 ℃.Superheater outlet leg arranges one road hydrophobic pipeline, and two drain valves are housed, and the drain pipe specification is φ 42 * 5.5, and laying thickness outside drain pipe is the glass wool insulation of 22mm, at the tube wall in hydrophobic valve downstream digital temperature sensor is installed.Through calculating, digital temperature sensor is installed in the thermal insulation layer apart from drain pipe outer wall surface 18mm place, can guarantee under the various operating modes, and its temperature is no more than 120 ℃.Ambient temperature is 30 ℃.Find through simulation calculation, drain valve begins to occur interior leakage by closing tight state, if when leakage flow is 0.084kg/s, experiences after 5 minutes, and relevant parameter tends towards stability.In one period transient time after fault occurs, by the wall surface temperature that digital temperature sensor is measured, its temperature rise rate δ₁, difference variation rate δ₃, and with the difference δ of ambient temperature₂Nonlinear over time, δ wherein₁, δ₃Changing Pattern consistent, excursion is 0.01-1.36 ℃/s.By the wall surface temperature of digital temperature sensor measurement and the difference δ of ambient temperature₂Also be increased to 66.2 ℃ by 9.7 ℃, temperature approach has increased by 56.5 ℃.Therefore, according to the temperature of digital temperature sensor collection, by analyzing wall temperature rise rate δ₁, difference variation rate δ₃, and with the difference δ of ambient temperature₂Changing Pattern, can in time the leakage failure of hydrophobic valve be identified 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 drop within protection scope of the present invention.

Claims (5)

1. 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 connected digital temperature sensor (1) on the drain water piping (11) that detected drain valve (10) connects, 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).

2. the online leakage detection apparatus of described Thermal Power Station's steam-water pipe drain valve according to claim 1, it is characterized in that, the digital temperature sensor (1) corresponding with each detected drain valve (10) all arranges a plurality of, they all are installed on the downstream drain water piping of detected drain valve (10), and along the axis arranged of drain water piping (11), corresponding all digital temperature sensors of one or more detected drain valves (10) (1) are connected by the signal input port of bus with same signal picker (3).

3. the online leakage detection apparatus of described Thermal Power Station's steam-water pipe drain valve according to claim 2, it is characterized in that, when adopting single thermal insulation layer (13) outside the drain water piping (11), digital temperature sensor (1) is installed in single thermal insulation layer (13), its position is to the distance of drain water piping (11) axis, and namely digital temperature sensor is installed radiusrBe calculated according to the following formula:

，

Wherein, r₁Be the drain pipe exterior radius; r₂Be the thermal insulation layer exterior radius; t₁Be the drain pipe outside wall temperature; t₂Be the thermal insulation layer outside wall temperature;tMaximum permission thermometric value for digital temperature sensor;

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

4. the online leakage detection apparatus of described Thermal Power Station's steam-water pipe drain valve according to claim 3, it is characterized in that, gather the measurement signal of digital temperature sensor, according to these Temperature numerical and variance ratio thereof, can whether exist leakage, leakiness situation to analyze judgement to hydrophobic valve;

Described trap leaking judgement is carried out as follows:

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

，

If:

And:

,

,

Then can judge trap leaking;

In the formula:

---hydrophobic tube wall average temperature value;

---theiThe measured value of individual digital temperature sensor;

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

---the time;

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

---for the warning limit value that the user sets, can set according to fluid properties, pipeline configuration situation in the drain water piping; Generally:

0.01-0.5 ℃/s,0.01-0.5 ℃/s,

Without gathering on the temperature difference basis of calculating under the leakage situation, increase 3-15 ℃.

5. the online leakage detection apparatus of described Thermal Power Station's steam-water pipe drain valve according to claim 4 is characterized in that, with

,,

Three parameters are as the sign parameter of trap leaking fault, and in conjunction with the principle of Fuzzy Pattern Recognition, further judge the trap leaking degree;

Concrete steps are:

At first with the amplitude of variation of each sign parameter, be converted to the fuzzy expression of sign parameter, represent four intervals that the sign parameter changes with 1,0.5,0.25,0, represent respectively the large and small degree of the amplitude of variation of each sign parameter, as follows:

，

，，

---the sign parameter

Corresponding failure symptom value;

---the sign parameterCorresponding failure symptom value;

---the sign parameter

Corresponding failure symptom value;

---the limit value that the sign parameter sharply raises, determine according to fluid properties in the drain valve of monitoring;

---the limit value that the sign parameter slowly raises, determine according to fluid properties in the drain valve of monitoring;

---the slight limit value that raises of sign parameter, determine according to fluid properties in the drain valve of monitoring;

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

，

Wherein,

,

,

,

Respectively correspondingly seriously leak, moderate is leaked, slightly leak and without leaking four kinds of typicalnesses;

According to the temperature data that gathers, the characteristic vector that arrangement obtains under the current working isu_x=, set up its fuzzy membership functions, calculate:

，i=1,2,3,4，

，i=1,2,3,4，

，i=1,2,3,4，

According to maximum membership grade principle, obtain:

，

Which state that can identify in the current running state of drain valve and the four kinds of typicalnesses approaches, and then makes the judgement of leakiness.

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