CN104236471A - Y-type double-FBG (fiber Bragg grating) optical fiber vibration sensor for online monitoring hydraulic decoking of coking tower - Google Patents
Y-type double-FBG (fiber Bragg grating) optical fiber vibration sensor for online monitoring hydraulic decoking of coking tower Download PDFInfo
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- CN104236471A CN104236471A CN201410527733.0A CN201410527733A CN104236471A CN 104236471 A CN104236471 A CN 104236471A CN 201410527733 A CN201410527733 A CN 201410527733A CN 104236471 A CN104236471 A CN 104236471A
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Abstract
The invention discloses a Y-type double-FBG (fiber Bragg grating) optical fiber vibration sensor for online monitoring hydraulic decoking of a coking tower. The Y-type double-FBG optical fiber vibration sensor comprises a vibration guide rod (2), a heat-radiating structure (3), a Y-type vibrating member (4), a sealing shell (5), a counterweight body (6), fiber Bragg gratings and a connecting base (1) supporting the whole sensor, a contact probe (10) at the left end of the vibration guide rod closely contacts with the wall of the coking tower, the heat-radiating structure is fixed on the vibration guide rod, the sealing shell is assembled on a fixing member (11) at the right end of the vibration guide rod through a screw port, the counterweight body and the Y-type vibrating member are positioned in the sealing shell, the first fiber Bragg grating is led out from one end of the Y-type vibrating member and then fixed on the sealing shell, and the second fiber Bragg grating is led out and pre-stretched from the other end of the Y-type vibrating member and then fixed on the sealing shell. The Y-type double-FBG optical fiber vibration sensor has the advantages of high response frequency, wide measuring range, safety in nature and the like, and can collect high-frequency vibrating signals generated when high-pressure water strikes the wall of the coking tower in the process of hydraulic decoking so as to complete hydraulic decoking process.
Description
Technical field
The present invention relates to field of sensing technologies, particularly the two FBG optical fibre vibration sensor of a kind of Y type of petrochemical industry coking tower hydraulic decoking on-line monitoring.
Background technology
Coking tower is one of visual plant of delayed coking unit in petroleum refining industry, it is mainly used in last link that enterprise of petrochemical refining produces, the principle of hydraulic decoking utilizes to be cut down by coke by the powerful impulsive force from hydraulic coke-cutting device nozzle high-pressure water jet out, hydraulic coke-cutting device nozzle is elevated and rotates in tower, coke in tower is come off, until whole for the coke in coking tower Ex-all.At present, domestic in the production run of petrochemical industry, nearly all by operating personnel by the coke water turbidity in chute bottom observing tower and listen to the sound cutting burnt process, judge the whether Ex-all of coke in coking tower according to working experience.Workman accurately cannot locate the change of thickness of coke layer and the position of coke cutter nozzle, make to repeat to cut burnt operating frequency high, work efficiency is relatively low, and chute and observation window is distant, larger with the impact of sight line round the clock by weather condition, such as at the weather of heavy rain or dense fog, operating personnel just cannot the situation of chute below accurate observation, this just causes larger trouble to cutting burnt work, have influence on and cut burnt efficiency and security, cause huge energy loss, increase labor strength.
In hydraulic decoking process on-line monitoring, abroad have at present adopt quartz tuning-fork measure the water attack of coking tower inner high voltage beat tower wall produce sound to judge the report of hydraulic decoking process, this system can monitor the clean level of decoking, can not monitor the change of thickness of coke layer in hydraulic decoking process and the position of coke cutter nozzle.In recent years, some units begin one's study the sensing measuring method of on-line monitoring hydraulic decoking process both at home and abroad, the detection that the people such as the Wang Tao of East China University of Science use quartz crystal sensor to be correlated with to the vibration signal in hydraulic decoking process.Similar coke on piezoelectric vibration sensors monitoring tower wall is also adopted to remove state as Luoyang JianGuang Petrochemical equipment Co., Ltd.Monitoring method due to them mainly adopts piezoeletric quartz sensor to measure tower wall vibrations signal, sensor used is mainly electrical sensor, by the impact of electromagnetic interference (EMI) and temperature, measuring accuracy is not high, and sensor layouts limited (generally below 8), be merely able to monitor from experiment effect the coking tower inwall got to focus layer from coke cutter nozzle water under high pressure out or beat at Ex-all coke, really can not monitor the change of thickness of coke layer in hydraulic decoking process and the comparatively accurate location of coke cutter nozzle.In technological means, because electrical sensor is positioned on the coking tower being integrated with multiclass electric equipment, electromagnetic interference (EMI) is inevitable, and the higher temperature of coking tower, inevitably reduces its measuring accuracy greatly in addition; In addition, electrical sensor will take encapsulation measure that the is explosion-proof and impact of reduction temperature, cause that volume is large and cost is high, the multiplexing characteristics etc. of electrical sensor limits its cloth on tower wall and counts in addition, really can not reflect the comparatively accurate location of thickness of coke layer Changing Pattern and coke cutter nozzle.
From Morey in 1989 first by Fiber Bragg Grating FBG (FBG) as since sensing element, optical fiber sensing technology receives extensive attention, obtains and develops rapidly.FBG sensor has explosion-proof, the electromagnetism interference of essence and signal can the plurality of advantages such as long-distance transmissions compared with traditional sensors.But yet there are no monitoring optical fiber raster vibration sensor being applied to hydraulic decoking process so far, key factor is in response frequency this limitation lower of existing fiber vibration transducer.
In order to improve response frequency and the job stability of optical fiber raster vibration sensor, Zhang Dongsheng etc. propose a kind of vertically push-pull type structure sensor; Xu Gang etc. also devise a kind of novel high frequency sensors.But these two kinds of sensor response frequencies are (below 3000Hz, below significant response frequency 2000Hz) on the low side still, can not meet the demand of hydraulic decoking monitoring the process to sensor response frequency.
Summary of the invention
Technical matters to be solved by this invention is: for the defect of above-mentioned prior art, there is provided a kind of Y type of coking tower hydraulic decoking on-line monitoring two FBG optical fibre vibration sensor, the problem of this sensor by being difficult to thickness of coke layer in the monitoring system of the collection solution coking tower hydraulic decoking of vibration signal differentiate to tower wall high-frequency method, Fibre Optical Sensor can not affect by temperature, electromagnetic interference (EMI) etc. simultaneously, uses more safely with convenient.
The present invention solves its technical matters and adopts following technical scheme:
The two FBG optical fibre vibration sensor of Y type of coking tower hydraulic decoking on-line monitoring provided by the invention, involving vibrations guide rod, radiator structure, Y type vibrating member, capsul, balance weight body and fiber grating, and support the connection pedestal of whole sensor, wherein: the contact sonde of vibration guide rod left end and coke drum tower wall close contact, radiator structure is fixed on vibration guide rod, capsul is assemblied on the fixture of vibration guide rod right-hand member by screw socket, capsul is equipped with balance weight body and Y type vibrating member, first fiber grating is fixed on capsul after one end of Y type vibrating member is drawn, second fiber grating is drawn from the other end of Y type vibrating member and is fixed on capsul after prestretched.
Described Y type vibrating member forms by pole with two arms arranged in fork-shaped that this pole upper end is fixedly linked, and the lower end of this pole is fixed on the bottom of capsul.
Described Y type vibrating member is positioned at the 150mm ± 5mm place, rear, radiator structure position on vibration guide rod, and it can be eliminated tower wall and conduct the compound movement, and only retains its normal vibration.
Described vibration guide rod is made up of contact sonde and stainless pipe, wherein: contact sonde is with arc, and this arc processes according to tower wall radian; Be connected with stainless pipe by laser bonding in the middle part of the arc of contact sonde.
Described radiator structure is made up of the circular ring metal sheet of some, and these circular ring metal sheets are fixed on vibration guide rod by screw thread.
The temperature that coke drum passes out by described radiator structure reduces, and makes the working temperature of described optical fiber FBG vibration transducer be no more than 100 DEG C.
The two FBG optical fibre vibration sensor of Y type of coking tower hydraulic decoking on-line monitoring of the present invention, the quality m of its response frequency and balance weight body is inversely proportional to, and is directly proportional to the vibration position vector of balance weight body.
The present invention can, by regulating quality and the vibration position vector of balance weight body, make the response frequency of optical fiber FBG vibration transducer of the present invention bring up to 3000 ~ 5000Hz.
The present invention compared with prior art has following technical advantage:
1.Y type vibrating member response frequency is high, and measurement range is comparatively large, and eliminates the impact of temperature on experimental result; Eliminated the vibration interference in other directions by the design of Y type vibrating member, only retain normal vibration, therefore, it is possible to precisely determine the change of thickness of coke layer;
2., by the quality of balance weight body and the vibration position vector of Y type vibrating member in the two FBG Fibre Optical Sensor of adjustable Y-shaped, high sensitivity and high response frequency can be obtained;
3. vibrate guide rod to contact with coking tower wall is closely knit, be convenient to the accurate propagation vibrated;
4. radiator structure eliminates the impact of coking tower wall temperature on sensor;
5. the state of hydraulic decoking can be obtained by measuring optical fiber grating optical signalling knots modification, more convenient to operate;
Accompanying drawing explanation
Fig. 1 is the one-piece construction of the two FBG optical fibre vibration sensor of Y type of coking tower hydraulic decoking condition monitoring.
In figure: 1. connect pedestal; 2. vibrate guide rod; 3. radiator structure; 4.Y type vibrating member; 5. capsul; 6. balance weight body; 7. fiber grating; 8. fiber grating; 9. tail optical fiber; 10. contact sonde; 11. fixtures.
Embodiment
Below in conjunction with accompanying drawing to sensor construction of the present invention with realize principle and be described further.
The two FBG optical fibre vibration sensor (hereinafter referred to as sensor) of Y type of coking tower hydraulic decoking on-line monitoring provided by the invention, its structure as shown in Figure 1, comprise and connect pedestal 1, vibration guide rod 2, radiator structure 3, Y type vibrating member 4, capsul 5, balance weight body 6, fiber grating 7, fiber grating 8, tail optical fiber 9, contact sonde 10, fixture 11 form, wherein: connect pedestal 1 and fix for the installation of whole sensor, this connection pedestal 1 is by the contact sonde 10 of vibration guide rod 2 left end and coke drum tower wall close contact.Radiator structure 3 is fixed on vibration guide rod 2.Capsul 5 is assemblied on the fixture 11 of vibration guide rod 2 right-hand member by screw socket.Y type vibrating member 4 with balance weight body 6 is fixed on the capsul 5 of sensor, and fiber grating 8 is fixed on capsul 5 through one end of Y type vibrating member 4.Fiber grating 7 is drawn from the other end of Y type vibrating member 4, fixed fiber grating 7 on capsul 5, and does prestretched to a certain degree, and then encapsulated by each element successively, preparation work completes.
Described connection pedestal 1 is a kind of chassis by being connected successively, support, annular fixing member form, wherein: chassis is connected with ground, annular fixing member is penetrated and vibrates on guide rod 2 and be fixedly linked by the flank vibrating guide rod, and support two ends are connected with annular firmware with chassis respectively by welding.
Described vibration guide rod 2 is that one is made up of contact sonde 10 and stainless pipe, wherein: one end (left side) of contact sonde 10 is with arc, and this arc processes according to tower wall radian; The other end of contact sonde 10 is connected with stainless pipe by laser bonding, to reduce to vibrate the distortion in conduction, improves the precision measured.The body of rod of vibration guide rod 2 is through the annular fixing member connecting pedestal 1, and the fixture 11 of the right-hand member tail end of this body of rod is connected by screw socket with capsul 5.
Described radiator structure 3 is fixedly linked by the body of rod of screw thread with vibration guide rod 2.This radiator structure 3 is made up of the circular ring metal sheet of some, and these circular ring metal sheets are fixed on vibration guide rod by screw thread.
Balance weight body 6 and Y type vibrating member 4 is provided with in described capsul 5.
Described Y type vibrating member 4 forms by pole with two arms arranged in fork-shaped that this pole upper end is fixedly linked, and the lower end of this pole is fixed on the bottom of capsul 5.
Described balance weight body 6 is a part for Y type vibrating member 4, two arms of Y type vibrating member 4 increase brachium during fiber grating forced vibration, enhance transducer sensitivity, but response frequency reduces thereupon, reduce the center of gravity of Y type vibrating member 4 to strengthen its response frequency by balance weight body, thus reach high, the highly sensitive high-technology index of sensor response frequency.
Described fiber grating comprises fiber grating 7 and fiber grating 8, wherein: after fiber grating 7 is drawn from the termination of an arm of Y type vibrating member 4, its lower end is fixed on capsul 5, and does prestretched to a certain degree.Fiber grating 8 is after the termination of another arm of Y type vibrating member 4 is drawn, and its underpart is fixed on capsul 5, and its tail optical fiber 9 passes the bottom of capsul 5.This tail optical fiber 9 is by being connected with demodulating system by extraneous terminal box.
The present invention is according to Elasticity and Fibre Optical Sensor theory, devise the two FBG optical fibre vibration sensor of a kind of Y type as shown in Figure 1, this sensor is carried out to the selection of structural dexterity design and structured material and grating length, the vibration frequency of optical fiber raster vibration sensor is derived according to model of vibration, amplitude and the fixing length of optical fiber 2, the quality of balance weight body, the relations such as the angle of Y type sensitivity compensation structure and the tension force of size and optical fiber, realize dither and highly sensitively two preferably to select, because the elastic modulus of the nature of sensor and the quality of oscillator and elastic construction is closely related.Along with the vibration of balance weight body 6, the wavelength of fiber grating 7 and fiber grating 8 drifts about thereupon, and intensity of reflected light changes along with the change of optical grating reflection wavelength difference, linear within the specific limits, and consistent with object vibration Changing Pattern.After balance weight body 6 is fixing, the vibration of vibration guide rod vertical direction can be eliminated, retain the dither being impacted the normal direction that tower wall produces by high-speed water jet.Along with the swing in balance weight body 6 horizontal direction, optic fiber grating wavelength drifts about, and intensity of reflected light changes along with the change of wave length shift, linear within the specific limits, and consistent with the vibration regularity of furnace wall.
The principle of work of the present invention is: the vibration guide rod 2 above with arc contact sonde contacts with coking tower wall is closely knit, under pressure water jets impact, coking tower wall produces local vibration, the vibration signal of coking tower will act on fiber grating by vibration guide rod, thus the optical signalling that change fiber grating high frequency vibration transducer reflects, the state of hydraulic decoking is judged by the knots modification measuring this signal.
Claims (8)
1. the two FBG optical fibre vibration sensor of the Y type of a coking tower hydraulic decoking on-line monitoring, it is characterized in that involving vibrations guide rod (2), radiator structure (3), Y type vibrating member (4), capsul (5), balance weight body (6) and fiber grating, and support the connection pedestal (1) of whole sensor, wherein: the contact sonde (10) of vibration guide rod (2) left end and coke drum tower wall close contact, radiator structure (3) is fixed in vibration guide rod (2), capsul (5) is assemblied on the fixture (11) of vibration guide rod (2) right-hand member by screw socket, capsul (5) is equipped with balance weight body (6) and Y type vibrating member (4), first fiber grating (8) is fixed on capsul (5) after one end of Y type vibrating member (4) is drawn, second fiber grating (7) is drawn from the other end of Y type vibrating member (4) and is fixed on capsul (5) after prestretched.
2. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 1, it is characterized in that described Y type vibrating member (4) forms by pole with two arms arranged in fork-shaped that this pole upper end is fixedly linked, the lower end of this pole is fixed on the bottom of capsul (5).
3. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 2, it is characterized in that described Y type vibrating member (4) and be embedded in the 150mm ± 5mm place, radiator structure (3) rear, position vibrated on guide rod (2), it can be eliminated tower wall and conduct the compound movement, and only retains its normal vibration.
4. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 1, it is characterized in that described vibration guide rod (2) is made up of contact sonde (10) and stainless pipe, wherein: contact sonde (10) is with arc, and this arc processes according to tower wall radian; Be connected with stainless pipe by laser bonding in the middle part of the arc of contact sonde (10).
5. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 1, it is characterized in that described radiator structure (3) is made up of the circular ring metal sheet of some, these circular ring metal sheets are fixed on vibration guide rod by screw thread.
6. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 5, it is characterized in that the temperature that coke drum passes out by described radiator structure (3) reduces, make the working temperature of described optical fiber FBG vibration transducer be no more than 100 DEG C.
7. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 1, it is characterized in that: the response frequency of this optical fiber FBG vibration transducer and the quality m of balance weight body (6) are inversely proportional to, and are directly proportional to the vibration position vector of balance weight body.
8. the two FBG optical fibre vibration sensor of the Y type of coking tower hydraulic decoking on-line monitoring according to claim 7, it is characterized in that: by regulating quality and the vibration position vector of balance weight body (6), make the response frequency of described optical fiber FBG vibration transducer bring up to 3000 ~ 5000Hz.
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