Title of Invention

A SONIC TUBE LEAK DETECTION DEVICE FOR BOILERS TO DETECT STEAM LEAKAGE OF BOILER TUBES

Abstract

This invention relates to a sonic tube leak detecting device (STLD) for boilers to detect steam leakage of boiler tubes comprising a sonic tube assembly, an acoustic sensor (1), a pr amplifier unit and a system panel, said sonic tube assembly comprises a matching unit (15), isolating unit (16) and a heat insulating coupling (17), said acoustic sensor comprises a coupling (18), an electronic unit (22), an insulated bush (21) a s.s.bush (19) and a connector (23), said system panel comprising a modular system electronics (24), a monitor (25), apc (26), an audio system (27), a key board (28) and a printer (29), the steam leak noise being converted into electric signal in the sensor (1) which is amplified in the preamplifier unit (2), the current signal and the voltage with frequency information being processed through the processor module,the out-put signal being simultaneously fed to a V/I converter (11), a comparator circuit (12), an analog remote display read out (13) and a computer system (14) for storage, mimic generation, graphical read out, historical and trend reporting,

Full Text

BACKGROUND OF THE INVENTION FIELD OF INVENTION This invention relates to sonic tube leak detection device for boilers to take corrective measures to avoid damages of boilers. Tube failures are considered as one of the major causes for any boiler outrage. If the leakage of steam from the boiler tube could be detected at an early of operation planned correction measures can be taken up to avoid serious secondary damages. DESCRIPTION OF PRIOR ART The conventional methods of detecting tube failure through steam leaks in boiler are either manually listening to audible leak or increase in make-up water requirements, both of which are operator dependent and hence such methods cannot detect leakage at an early stage for taking required precautions. The present invention intends to detect the steam leakage at its nascent stage itself, electronically through sensing acoustic emission thus increasing plant availability and improvement in performance. The applicants have developed a new device to avoid the disadvantages of the conventional methods. The present invention related to sonic tube leak detection system (STLD) comprising of the following sub systems; 1. . Sonic tube assembly 2. Ac: ou s tic sen so r 3. Pre amplifier unit 4. System p an e1 To locate the steam leakage inside the furnace, STLDs are installed into a number of zones and each zone is monitored by one channel. The system is designed to monitor 12, 18 or 24 zones (being modular in design, higher number of channels can also be accommodated as per customer requirement). In each zone, one sonic tube assembly is installed, which penetrates the boiler casing and terminates at the edge of the boiler water wall tubing. On the other side of the sonic tube assembly, an acoustic; sensor is mounted. Sound signal reaching the acoustic sensor assembly is converted into electrical signal and is amplified in the preamplifier unit, which is kept close to the sonic tube assembly. The preamplifier has specially designed filter to eliminate combustion noise. The filtered signal from the pre amplifier units of each channel is taken to system panel, which contains signal processor modules. The signal is processed further using solid-state circuitry to obtain the steam leak information in decibels (dB>, A PC software acquires the output of the processed signal and produces output in various display formats like Bargrapb, Mimic, Group trend and History in the PC. The system has provision to variably set threshold values of sound levels (in dB) and to activate alarm if sound level exceeds the threshold value in any channel. Additionally current outputs representing the detected sound levels from each channel is provided, to be useful for- the customer. PRIOR ART DISCUSSION Prior art search was conducted for leak detection systems and it is found that they have been generally disclosed i n t h e f o 11 o w i n g p ate n t s . US Patents 4998439 discloses the design of Acoustic wave guide shape with up to 90 bend along with tubular axis, whereas, the invented wave-guide design as described herein below is different from the above patent design is 1.2 meter long steel tube with ball valve and 45 elbows at one end. The end of the elbow is mounted with a heat insulated coupling to reduce heat transfer to acoustic sensor. US Patent: 5623421 reveals a method for monitoring pressurized vessels, where the transducers are physically attached to the vessel and transmit the vibratory acoustic signals, which are processed to extract the frequency spectra of the signals. In the invented new design, the method of detection is different since it is based on acoustic signals transmitted through air/gas medium and the sonic sensor is mounted away from the boiler waterwall steam pipes. In US Patent: 5,101774 acoustic leak detection has been dislosed. Acoustic signals are passed to a sequential multiplex switching unit and the output of the multiplexer is further processed using Fast Fourier Transform (FFT) techniques. The present invention includes a method of signal processing which is different from the above patent. The acoustic signal is processed by analog circuits for each channel separately and displayed in the color monitor. Failure of one channel will not affect the performance of other channels. US Patent: 535,16515 discloses acoustic emission signal. The signal travels along the surface of the tube and then along the surface of the attached waveguide into the cross member where it is detected by the acoustic emission sensor which is connected to signal processing controls. In the new method the construction of sonic tube is different with 45 degree elbow and also further sensing and processing are different from the above prior art patents. The signals are digitalized in a rapid time sequence such digital values are temporarily stored in dsta memory bank and displayed are known and disclosed in US Patent: 4960079. In the design disclosed herein, the signals are processed by analog circuits and the values are displayed in a microprocessor based data scanner und also in a PC monitor. US Patents 4502322 describes an apparatus for detecting leaks in steam raising boilers. In the above referred patent the listening tube is 1 meter in length. The free end of the tube is formed with an elbow, the elbow is made of a plastic material. The sensor is mounted on the listening tube, it receives the acoustic signal and processed by analog circuits and the output is displayed in the LED Bargraph. The invented design is different and is provided with the free end of the sonic tube elbow is of steel material, with heat insulated coupling. The sonic sensor is located on the heat insulated coupling. The acoustic Bignal is sensed by the sonic sensor and the signal is processed and displayed in the microprocessor dB scanner and also displayed in the PC monitor using s o f t w are. Prior US Patents 43.27f.76 relates to acoustic leak d e t e c t o r. In this application for patent, the device processes the acoustic signals from the source of the leak and indicates the leak in the edgewise indicator. One of the objects of the present invention is to mitigate the drawbacks of the prior art. Another object of the present invention is to provide a new sonic tube leak detection system in boiler in detecting the sound generated steam leakage. A further object of the present invention is to provide a sonic tube leak detection system so as to avoid secondary damage for boilers, A still further object of the present invention is to minimize tube failure causing boiler outrage. A further object of the present invention is to detect the leakage of steam from boiler tube at an early stage of operation so that correct measure can be taken up to avoid serious damages in the boiler. To avoid all the disadvantages of the prior art in detection of the leakage in the boiler manually and to provide an effective sonic tube leakage detection, the scope of the present invention will be clear from the following description. In the present device, the steam leakage signals are processed by the analog circuits and are further scanned by the microprocessor based dB scanner. The leak dB values are indicated in this scanner itself. The output of this scanner is linked to a PC to indicate leak information in Bargraph, Mimic, History, Trend and Group trend formats According to the present invention there is provided a sonic tube leak detecting device (STLD) for boilers to detect steam leakage of boiler tubes comprising a sonic tube assembly, an acoustic sensor, a pre amplifier unit and a system panel, said sonic tube assembly comprises a matching unit isolating unit and a heat insulating coupling, said acoustic sensor comprises a coupling, an electronic unit, an insulated bush as.s.bush and a connector, said system panel comprising a modular system electronics, a monitor, apc, an audio system, a key board and a printer, said sonic tube assembly being installed by penetrating the boiler water casing and terminating at the edge of the boiler water wall tubing, the steam leak noise being converted into electric signal in the sensor which is amplified in the preamplifier unit the current signal being fed to I/V converter located in the processor module, the voltage with frequency information being filtered in the band-pass filter unit passed through an absolute value circuit and a dB converter amplifier the output of which being made free of noise through a subtracter unit, the out put signal of the substractor containing noise leak information being simultaneously fed to a V/I converter, a comparator circuit, an analog remote display read out and a computer system for storage, mimic generation, graphical read out, historical and trend reporting to detect sonic leak of the boiler tube. In the above sonic tube leak detection device, the acoustic leak sensor is located at one end of said sonic tube assembly which is provided with a high heat insulated coupling to protect the sensor from heat conduction for the pipe. The acoustic leal: device of STLD is of sealed typed so that said senor is protected from the dust environment, said sensor is designed in analog circuitry to have the maximum system availability. Further, said system is designed in modular type and thereby the limitation of number of channels are eliminated. The sonic tube leak detection device (STLD) of the present invention is designed to have independent channel so that failure of one channel will not effect the other channels, resulting in enhanced system availability. The sonic tube leak detection device of the present invention is described hereinbelow in detail with reference to the accompanying drawings, wherein - Figure 1 illustrates a block diagram; Figure 2 illustrates a sonic tube assembly; Figure 3 shows an acoustic sensor, and Figure 4 shows a system panel. The sonic tube assembly as illustrated in Figure 2, comprises a matching unit (15), isolation unit (16) and a heat insulated coupling (17). The acoustic sensor as shown in Figure 3, comprises a coupling (18) a stainless steel (s.s) bush (19), a housing (20), an electronic unit (22), an insulated bush (21) and a connector (23). The system panel as shown in Figure 4 comprises a modular system electronics (24), a monitor (25), a PC (26), an audio system (27), a keyboard (28), and a printer (29). The acoustic sensor (1) is located at one end of sonic tube assembly. The steam leak noise reaching the sensor (1) is converted into electric signal and is amplified in the pre-amplifier unit (2) which is located near the sonic tube assembly. Further unwanted combustion noise is filtered and converted in the filter unit (3) and V/l converter (4) provided in the pre-amplifier unit. The current signal is fed to I/V converter (6) located in the processor module (5). The voltage with frequency information is filtered in the band-pass filter unit (7). The filtered band is passed through an absolute value circuit (8) and dB converter amplifier (9) for decade amplification. The dB converter amplifier output is made free of background noise through a subtracter unit (10). The output signal of subtracter containing sonic leak information is simultaneously fed to a) V/I converter (11) for generating 4-20 mA signal, b) comparator circuit (12) for alarm generation, c) analog remote display read-out (13) and d) a computer system (14) for storage, mimic generation, graphical readout, historical and trend reporting to detect sonic leak of the boiler tube. The invention has described hereinabove is by way of an example without restricting the scope there through. The modifications and improvements of the sonic tube leak detection system (STLD) of the present invention may have other variations which is within the knowledge of a person skilled in the art and as intended to be covered within the scope of the present invention. I A sonic tube leak detecting device (STLD) for bolters to detect steam leakage of bailor tubes comprising a sonic tube assembly, an acoustic sonsor (1), a pre amplifier unit and a system panel, said sonic tube assembly comprises a matching unit (15), isolating unit (16) and A heat inan coupling (17), said acoustic sensor comprises a coupling (18), an electronic unit (22), on insulated bush (21) as bush (19) and a connector (23), said system panel comprising a modular system electronics (24), a monitor (Z5), a pc (26), an audio system (27), a key board (28) and a printer (29), said sonic tube assembly being installed by penetrating the bodef water casing and terminating at the edge of the boiler water wall tubing, the steam loft noise being converted into electric signal in the sensor (1) which is an plified in the preamplifier unit (2), the current signal being fed to I/V converter(6) located in the processor module, the voltage with frequency information being filtered in the b and-p MS filter unit (7) paused through an a so life value circuit (8) and a dB converter amplifier (9 output of which being made free of noise through a subtractor unit (1 ), the output signal of the sub stractor containing noise leak information being simultaneously fed to a V/I convertor (11), a comparator circuit (12), characterized in that said ftoouitic sensor is mounted away from the boiler waterwall tubing, function with Acoustic signals transmitted through air/ gas medium, the processing of the signal being analog in nature, the varvps being ditplaypd in microproessor bases data scanner, said sonic tube having a heat in SB Latal coupling which house the said sensor, said sensor being sealed type said detection system being in modular type to eliminate limitation of number of channels and said channels being independent of one another.

Documents:

1140-del-2002-abstract.pdf

1140-del-2002-claims.pdf

1140-del-2002-correspondence-others.pdf

1140-del-2002-correspondence-po.pdf

1140-del-2002-description (complete).pdf

1140-del-2002-drawings.pdf

1140-del-2002-form-1.pdf

1140-del-2002-form-19.pdf

1140-del-2002-form-2.pdf

1140-del-2002-form-3.pdf

1140-del-2002-form-4.pdf

1140-del-2002-form-5.pdf

1140-del-2002-gpa.pdf

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