Description:FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003

COMPLETE SPECIFICATION
[See section 10 and rule 13]

TITLE: “A SYSTEM AND A METHOD FOR MEASURING LENGTH OF A TUBE”

Name and Address of the Applicant:
TATA STEEL LIMITED, Jamshedpur, Jharkhand, India 831001.

Nationality: INDIAN

The following specification particularly describes the nature of the invention and the manner in which it is to be performed.
TECHNICAL FIELD

The present disclosure relates in general to the field of metallurgy. Particularly, but not exclusively, the present disclosure relates to a system and a method for measuring length of tubes in high temperature applications. Further embodiments of the present disclosure disclose a system and a method for measuring the remnant length of tubes employed in high temperature operating conditions such as furnace or kiln in metallurgical plant.
BACKGROUND

Generally, majority of the industrial manufacturing plants make use of large burners or other heat transfer and heat conducting means. Provision of heat is an important step in majority of the material manufacturing and processing industries. Combustion in industrial burners is a critical operation in the chemical process industries for supplying thermal energy for heat transfer, fluid heating, steam generation, distillation, metal melting industries, cement industries and others. Burners are mechanical devices utilized for mixing proper quantities of fuel and air, and also for maintaining stable flame inside fired equipment. Industrial process burners can be broadly classified into raw gas burners and pre-mix burners. Raw-gas burners are used for most of the applications. In the raw gas burners, the fuel passes through an orifice or a tube and the fuel is injected directly into the combustion zone, where it mixes with air. Pre-mix burners are those in which fuel and air may be mixed prior to combustion. Pre-mix burners are used in specialized applications where there exists lack of oxygen for suitable combustion. The air and the fuel are mixed in a tube and are ignited at the end or at the tip of the tube.

As mentioned above, a majority of the burners use an elongated tube for supplying fuel to a combustion zone, where the fuel along with air is then ignited at the tip of the tube for generating the required heat. Since, these fuel supply tubes always operate at very high temperatures and are often provisioned in extremely harsh operating conditions, the tubes may be subjected to extreme fatigue and corrosion. This fatigue and corrosion further lead to the thinning of the material at the tip of the tubes and these thin ends of the tubes may break or disintegrate into very small pieces. The broken pieces of the tube fall down in the combustion chamber and further get mixed with the material in the combustion chamber. As a result of this mixing of the particles of the tube with the material in the combustion chamber, the purity of the material inside the combustion chamber reduces.

The reduction of the tubes in burners is explained below with reference to the operation of the burner lances in a lime kiln. The measurement of the remnant length of the tube is very critical for smooth operations in the lime plant. The essential factors in the operation of a lime kiln is the decomposition of the limestone. For achieving the decomposition of the limestone, stone must be heated to the dissociation temperature of the carbonates and the minimum temperature must be maintained for a certain duration. This temperature inside the kiln is achieved by the supply of combustible gases through numerous tubes or lances present along the circumference of a shaft in the kiln. At the tip of the tube, combustion takes place and the process of decomposition of limestone into lime is initiated. The tip of the lances should be at the same level forming isotherm plane which helps in the uniform decomposition of lime. The temperature at the tip of lance ranges from 650°C to 950 °C and the chemical reaction of decomposition requires at least 900 °C. These lances are under always loading from external temperature as well as burden movement of limestone, so there is a high probability that erosion from the exterior may be caused. The corrosive environment of the gases flowing inside the lance may lead to thinning at the location near the tip. These conditions in which tubes are present pose a high risk of thinning of the structure and may get separated from the tubes resulting in a reduction of the length of the tube. The broken part of the structure moves along with the lime and will be carry forwarded to its further operations in the plants affecting the process. The reduced lance in the shaft of lime kiln results in a shift of ideal isotherm plane which in turn affects the quality of the lime produced, this is due to over burning of the lime at the locations where the length of the tube was reduced.

Conventionally, in order to prevent the mixing of broken parts of the burner tube with the lime in the lime kiln, the tubes may be replaced at predefined interval of time so that breakage of the tube may be avoided. To replace such tubes, working life of the tube in the burner may be initially estimated and accordingly, the tube may be replaced at regular intervals. Such regular replacement of the tubes requires for the whole lime kiln to be shut down, thereby affecting the manufacturing process. Further, following time schedules for replacing the tubes increases the possibilities of replacing the tube prematurely, even though there exists no significant reduction in the length of the tubes.

With advancements in the technology systems and method have been developed to determine the length of tube before replacement. In one such method, mechanical attachments are inserted through interior walls of the tube and guided waves are transmitted to the structure externally for detecting anomalies like cracks, corrosion patches and wall thinning. The transmitted guided waves are reflected back when they encounter anomalies like cracks, corrosion patches, wall thinning etc. Other conventional methods include making use of the target tube itself as a waveguide by exciting, either by an array of piezoelectric elements or magneto strictive means for generation of guided waves. These techniques create complications when measuring the length of structures where the end is corroded, and when the wall thinning phenomenon is prevalent at the end of the tube. The wall thinning phenomenon and the corrosion at the tip cause the guided wave energy to die even before reaching the end of the structure. Therefore, measurements of the tube dimensions are often inaccurate.

Document “WO2000043746A1” teaches a system which incorporates an external mechanism for generating guided waves of size small enough for insertion into a target tube and an arrangement is provided to maintain mechanical contact to the target tube. The insertion of interrogating waves at a single point in the cylindrical wall of the tube creates conflicting wave patterns that complicate the detection and analysis of the returned signals from anomalies. Also, since the target tube itself as a waveguide, wall thinning phenomenon and the corrosion at the tip cause the guided wave energy to die even before reaching the end of the tube.

The present disclosure is directed to overcome one or more limitations stated above or other such limitations associated with the conventional systems.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the conventional system and method are overcome by the system and method as claimed and additional advantages are provided through the provision of the system as claimed in the present disclosure.

Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the disclosure, a system for measuring length of a tube is disclosed. The system includes a waveguide extending along a passage of the tube. A transceiver is coupled to the wave guide, where the transceiver is configured to transmit a signal of a pre-determined velocity through the waveguide and receive a reflected signal through the waveguide. Further, the time of flight of the reflected signal is suitably indicated, where the time of flight (TOF) of the reflected signal is indicative of the length of the tube.

In an embodiment of the disclosure, the transceiver generates a waveform based on the received reflected signal through the waveguide.
In an embodiment of the disclosure, an indication unit is associated with the transceiver, wherein the transceiver is configured to indicate the waveform of the reflected signal transmitted through the waveguide by the indication unit.

In an embodiment of the disclosure, the signal transmitted by the transceiver is an ultrasound signal.

In an embodiment of the disclosure, the waveguide is made of same material as that of the tube.

In an embodiment of the disclosure, the waveguide conforms to the shape of the tube.

In an embodiment of the disclosure, the waveguide is a wire.

In an embodiment of the disclosure, the signal transmitted by the transceiver is a shear horizontal wave.

In an embodiment of the disclosure, the signal transmitted by the transceiver is at least one of 0.25 MHz, 0.5 MHz and 1 MHz.

In an embodiment of the disclosure, the signal transmitted by the transceiver is normal shear wave transducer.

In one non-limiting embodiment of the disclosure, a method for measuring length of a tube is disclosed. The method comprises steps of inserting a waveguide along the length of the tube and coupling the waveguide to a transceiver. Further, transceiver transmits a signal of a pre-determined velocity through the waveguide and receives a reflected signal through the waveguide. Further, the time of flight of the reflected signal is indicated. The time of flight (TOF) of the reflected signal is indicative of the length of the tube.

In an embodiment of the disclosure, the length covered by transmitted and reflected signal, is indicative of twice the length of the tube.
In an embodiment of the disclosure, the waveguide conforms to the shape of the tube as the waveguide is inserted into the tube.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristics of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

Fig. 1 is a schematic representation of a kiln shell of a burner with a plurality of tubes, in accordance with an embodiment of the present disclosure.

Fig. 2 is a schematic representation of a system for measuring length of a tube, in accordance with an embodiment of the present disclosure.

Fig. 3 illustrates multiple configurations of placing the transceiver on the tube, in accordance with an embodiment of the present disclosure.

Fig. 4a, 4b, 4c and 4d illustrate a graphical representation of waveforms displayed by an indication unit of the system of Fig. 2 for tubes of different lengths, in accordance with an embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the system and the method for measuring length of a tube and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other devices for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure. The novel features which are believed to be characteristic of the disclosure, as to its organization, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a system that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such mechanism. In other words, one or more elements in the device or mechanism proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the mechanism.

Embodiments of the present disclosure discloses a system for measuring length of a tube. In conventional methods of measuring the length, target tube itself is used as a waveguide. However, such technique create complications when measuring the length of tube where the end is corroded, and when the wall thinning phenomenon is prevalent at the end of the tube. The wall thinning phenomenon and the corrosion at the tip cause the guided wave energy to be attenuated even before reaching the end of the structure. Therefore, measurements of the tube dimensions using such a method may be inaccurate.

Accordingly, the present disclosure discloses a system and a method for measuring the length of the tube. The system comprises of a waveguide extending along a passage of the tube. A transceiver is connected to the tube and coupled to the wave guide. The transceiver is configured to transmit a signal of a pre-determined velocity through the waveguide. In an embodiment, the transmitted ultrasound wave reaches the tip of the waveguide and reflects from the tip of the waveguide. The reflected signal is received by the transceiver through the waveguide. Further, the time of flight (TOF) of the reflected signal is calculated to determine the length of the tube.

The following paragraphs describe the present disclosure with reference to Figs. 1 to 4.

Fig. 1 illustrates a schematic representation of a kiln shell (4) of a burner of a a lime kiln plant with plurality of tubes (6). A lime kiln plant is generally employed in the metal industry such as steel industry for decomposing limestone into lime and the decomposition process may be aided by supplying heat or by burning the limestone. Every lime kiln comprises of a burner for initiating and maintaining the combustion process required for the decomposition of limestone. The lime kiln may include a kiln shell (4) which houses the burner of the lime kiln. The burner may further be provisioned with plurality of tubes or lances (6) and the burner may be housed in the kiln shell (4) of the lime kiln. The tubes (6) may extend through the kiln shell (4) and may be directed towards the combustion zone of the lime kiln. Each of the plurality of tubes (6) that extend through the kiln shell (4) may be suitably provisioned with a flange (3). Each of the flanges (3) coupled to each of the tubes (6) may further be provided with at least one air inlet (1) and fuel inlet (2).
With further reference to Fig. 1, the fuel inlet (2) of the plurality of tubes (6) is initially opened and the fuel may be directed though the tubes (6) into the combustion zone of the lime kiln for a pre-determined amount of time. The fuel reaches the tip or the tube end (Z) and may be ignited by a suitable ignition means. The air in the combustion zone along with the fuel supplied through the tube (6) combust at the tube end (Z) and cause the limestone in the lime kiln to decompose to lime. The kiln may comprise of a plurality of shafts and each of the shaft may be provided with multiple tubes (6). While the tubes (6) in one of the shafts may be supplied with fuel, the tubes (6) in the other shaft may be supplied with air by the air inlet (1) for a pre-determined amount of time. Air may be supplied to the tubes (6) in the second shaft for cooling of the tubes (6) in the second shaft. Further, the above mentioned roles of the tubes (6) in the first shaft supplying fuel and the tubes (6) in the second shaft supplying air may be reversed after a pre-determined amount of time and accordingly the tubes (6) in the first shaft may be circulated with air whereas the tubes (6) in the second shaft may be supplied with fuel. Thus, the second shaft may supply the fuel required for combustion while the first shaft is being cooled by the circulating air. Fig. 1 only depicts two tubes (6), however, multiple tubes (6) may be configured in a single given shaft. Further, multiple shafts may be provided in a burner and the supply of fuel for combustion and the circulation of air for cooling through the shafts may be alternatively staged.

Now referring to Fig. 2 which illustrates a schematic representation of a system (100) for measuring length of a tube (6). As shown in Fig. 2 at least one waveguide (9) may be inserted through each of the multiple tubes (6). In an embodiment, the waveguide (9) may be made of the same material as that of the tube (6). The waveguide (9) is inserted into the tube (6), such that the waveguide (9) conforms or takes the shape of the tube (6). The waveguide (9) used may be flexible and the waveguide (9) may bend along all the corners of the tube (6). In an embodiment of the disclosure, the waveguide (9) may be provisioned with suitable support means such that the waveguide (9) extends along a substantially central portion of the tube (6). The waveguide (9) is inserted through the tube (6) such that the waveguide (9) extends throughout the length of the tube (6) till the tip of the tube (6).. One end of the waveguide (9) extends into the combustion zone of the lime kiln, whereas the other end the waveguide (9) is inserted into the tube (6) that may be provided with a transceiver (8). The transceiver (8) that is positioned at an end opposite to the combustion zone of the tube (6), may be coupled to the waveguide (9) that extends throughout the length of the tube (6). The transceiver (8) may be further connected to a suitable power supply by means of a connector (7). The transceiver (8) may be configured to transmit and receive signals and acts as a transducer and a receiver. The transceiver (8) may generate a required mode of guided waves using an ultrasonic transducer. The ultrasonic transducer may be a piezoelectric transducer where the vibrations of the piezoelectric crystals generate the required ultrasound waves. In an embodiment, the transducer may be a normal shear wave transducer which transmits a horizontal shear wave with a frequency of 0.5 MHz. The transmitted ultrasound waves may travel along the length of the waveguide (9) and may be reflected back when the transmitted waves reach the tube end (Z). The fuel is transmitted through the tubes (6) from a high-pressure environment to an environment with lower pressure. The fuel that is transmitted through the tubes (6) may be usually highly pressurized. This fuel is ignited inside the combustion zone. Further, as the transmitted wave reaches the tip of the waveguide (9), it gets reflected back. The reflected wave is detected by a receiving unit of the transceiver (8) and is further suitably indicated by an indication unit (10). The indication unit (10) may be connected to the transceiver (8) by a connector (7). In an embodiment, the transceiver (10) may be configured to be an indication unit (10). In an embodiment, the indication unit (10) may be an oscilloscope which indicates the ultrasound waves being transmitted and reflected through the waveguide (9). In an embodiment of the disclosure, the transceiver (8) may receive the reflected wave from the waveguide (9) and may automatically indicate the reflected wave in a suitable waveform. An example of the results displayed on the indication unit (10) is shown in the Fig. 4a. The peak amplitude (P) depicts the point of reflection of the ultrasound wave and is indicative of the end point or the tube end (Z). The indication unit (10) also indicates the twists and bends in the waveguide (9) as peak amplitudes (P). Further, these peaks in the waveform along the X-axis of the waveform are recognized to detect the tube end (Z). An operator who analyses the waveform depicted by the indication unit (10), may clearly identify the peak amplitudes (P) that are depicted in the waveform due to the bends in the waveguide (9). The operator may ignore the peak amplitudes (P) that are caused due to the bends in the waveguide (9) and may clearly identify the peak amplitude (P) in the X-axis of the waveform that is caused due to the reflection of the ultrasound wave. Further, the time of flight (TOF) of the reflected ultrasound wave to travel back to the transceiver (8) is calculated. Further, the ultrasound wave is transmitted through the waveguide (9) at a pre-determined velocity. Accordingly, from the above two factors of the TOF and the velocity at which the ultrasound wave is transmitted through the waveguide (9), the length of the tube (6) may be calculated. The ultrasound wave travels to and fro through the waveguide (9) (i.e. during transmission and while being reflected). Since, the ultrasound wave that is received by the transceiver (8) travels twice the length of the tube (once during being transmitted and once while reflected), the length is calculated by dividing the obtained value by 2. Further, Fig 4a-4d, are illustrative of the TOF for tubes (6) of different length. As seen from Fig, 4b, the TOF is 2460 micro seconds, which is indicative of a tube (6) length of 6000mm. As observed from Fig 4c and 4d, a reduction in TOF is indicative of reduction in length of the tube (6).

In an embodiment of the disclosure, modes of excitation of guided waves in the waveguide (9) by the transducer may be piezoelectric, laser, magneto strictive and electromagnetic based transduction.

In operation, when the burning of the fuel takes place at the tube end (Z), by supplying fuel through the plurality of tubes (6), the waveguide (9) that extends till the tip of the tube (6) or till the tube end (Z) is also subjected to high temperatures. Further, when the tube end (Z) begins to disintegrate, the waveguide (9) becomes exposed to the corrosive environment in the combustion zone and the waveguide (9) gets consumed or disintegrates due to high temperatures in the combustion zone. Since, the limestone in the combustion zone is inherently corrosive, the tube end (Z) that lies in the combustion zone may also be subjected to corrosion. Also, the high operating temperatures and the corrosive environment in the combustion zone of the lime kiln, causes the tube end (Z) to be subjected to wall thinning. This reduction in thickness of the tube end (Z), further causes the material to disintegrate and overall length of the tube (6) may also be proportionately reduced. Further, when an ultrasound wave is transmitted through the waveguide (9), the ultrasound wave gets reflected back when it reaches the tube end (Z). Since, the length of the tube (6) and the length of the waveguide (9) is reduced due to harsh operating conditions in the lime kiln, the ultrasound wave is reflected more quickly and the TOF of the reflected wave is also reduced. Further, as long as the waveguide (9) lies inside the tube (6), the waveguide (9) remains intact without breakage or any damage and represents the correct length of the tube (6). Further, when wall thinning and breakage of the tube (6) occurs, then the waveguide (9) will be exposed to the harsh combustion zone and corrosive environment causes the waveguide (9) to be consumed away at a faster rate. Thus, the waveguide (9) whose length is reduced as it is exposed to the corrosive environment will represent the true length of the reduced tube (6). Also, length of the tube (6) may further be calculated from the reduced TOF. A quick comparison between the calculated initial length of the tube (6) and the length of the tube (6) after a pre-determined time indicates the reduction in length of the tube (6). Accordingly, the operator may suitably replace the tube (6) in the burner.

In an embodiment of the disclosure, the user may only proceed to take measurements from the waveform of the indication unit (10) after a couple of minutes of the operation of the burner. The user may initially ensure a proper acoustic coupling with the transceiver (8) and the waveguide (9). The user may wait for a pre-determined amount of time before the transceiver (8) is configured to emit ultrasound waves through the waveguide (9). Operating the burner for a pre-determined amount of time before taking the readings from the waveform achieves the purpose of deliberately disintegrating or sacrificing the waveguide (9) so that the length of the waveguide (9) becomes equal to the length of the tube (6). Further, a special shear wave coupling means may be used to minimise the loss of energy and effectively transfer the ultrasound waves into the waveguide (9).

In an embodiment of the disclosure, the transceiver (8) may be coupled to a controller and the controller may be configured to detect the peak amplitude (P) in the waveform that is caused due to the reflection of the ultrasound wave at the tube end (Z) and accordingly calculate and indicate the length of the tube (6) based on factors such as TOF of the reflected ultrasound wave and the velocity of the ultrasound wave.

Fig. 3 illustrates multiple configurations of placing the transceiver (8) on the tube (6). In an embodiment, the transceiver (8) may be placed on the sides or along the length of the tube (6).

In an embodiment of the disclosure, transmission of the ultrasound waves is completely dependent on the waveguide (9) and not on the internal or the external surfaces of the tubes (6). Consequently, the reflection of the ultrasound wave is accurate and the there exists no possibilities of attenuation of the ultrasound wave since the waveguide (9) is not in contact with the tube (6) surface.

In an embodiment of the disclosure, premature replacement of the tube (6) may be prevented by monitoring the length of the tube (6) by means of the waveguide (9) and the tube (6) may be replaced only when a reduction in length is observed.

Equivalents

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

It will be understood by those within the art that, in general, terms used herein, are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding the description may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated in the description.

Referral Numerals:

Description Referral numerals
Air inlet 1
Fuel inlet 2
Flange 3
Kiln shell 4
Kiln interior 5
Tube /Lance 6
Connector 7
Transceiver 8
Waveguide 9
Indication unit 10
Tube end Z
Peak Amplitude P

Claims:We Claim:

1. A system (100) for measuring length of a tube (6), the system (100) comprising:
a waveguide (9) extending along a passage of the tube (6);
a transceiver (8), coupled to the waveguide (9), wherein, the transceiver (8) is configured to:
transmit a signal of pre-determined velocity through the waveguide (9) and receive a reflected signal through the waveguide (9), and
indicate, time of flight of the reflected signal, wherein the time of flight (TOF) of the reflected signal is indicative of the length of the tube (6).

2. The system (100) as claimed in claim 1, wherein the transceiver (8) generates a waveform based on the received reflected signal through the waveguide (9).

3. The system (100) as claimed in claim 1, comprising an indication unit (10) associated with the transceiver (8), wherein the transceiver (8) is configured to indicate the waveform of the reflected signal transmitted through the waveguide (9) by the indication unit (10).

4. The system (100) as claimed in claim 1, wherein the signal transmitted by the transceiver (8) is an ultrasound signal.

5. The system (100) as claimed in claim 1, wherein the waveguide (9) is made of same material as that of the tube (6).

6. The system (100) as claimed in claim 1, wherein the waveguide (9) conforms to the shape of the tube (6).

7. The system (100) as claimed in claim 1, wherein the waveguide (9) is a wire.

8. The system (100) as claimed in claim 1, wherein the signal transmitted by the transceiver (8) is a shear horizontal wave.

9. The system (100) as claimed in claim 1, wherein the signal transmitted by the transceiver (8) is at least one of 0.25 MHz, 0.5 MHz and 1 MHz .

10. The system (100) as claimed in claim 1, wherein the signal transmitted by the transceiver (8) is normal shear wave transducer.

11. A method for measuring length of a tube (6), the method comprising:
inserting a waveguide (9) along the length of the tube (6) and coupling the waveguide (9) to a transceiver (8);
transmitting, by the transceiver (8), a signal of a pre-determined velocity through the waveguide (9), and receiving a reflected signal through the waveguide (9);
indicating the time of flight of the reflected signal, wherein time of flight (TOF) of the reflected signal is indicative of the length of the tube (6).

12. The method as claimed in claim 11, wherein the transceiver (8) generates a waveform based on the received reflected signal through the waveguide (9).

13. The method as claimed in claim 12, comprising, indicating by an indication unit (10) associated with the transceiver (8), the waveform of the reflected signal transmitted through the waveguide (9).

14. The method as claimed in claim 11, wherein the length covered by transmitted and reflected signal, is indicative of twice the length of the tube (6).

15. A burner of a lime kiln comprising the system (100) as claimed in claim 1 for measuring a length of a tube (6) in the burner.