METHOD OF FURNACE OPERATION BY THERMOCOUPLE PLACEMENT IN FURNACE BOGIE

TECHNICAL FIELD
[0001] The present disclosure relates methods and tools used for operating a horizontal single bogie or a double bogie hearth furnace with innovative method of thermocouple placement to increase the operation performance, equipment availability and operator safety.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present subject matter. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed subject matter, or that any publication specifically or implicitly referenced is prior art.
[0003] High quality heat treatment such as normalising or quenching and tempering can be carried out with good temperature control in this type of furnaces.
[0004] Various approaches have been proposed in the state of the art in connection with the heat treatment of large fabricated parts. For instance, EP Patent bearing publication no. EP 0085733 A1 to Ryoji Terakado et. al. teaches about a vertical continuous annealing furnace and its operating method particularly suited for annealing strips of such special steels as stainless steel.
[0005] Also, US Patent US 3496033 A to Gilbreath Eddie W Jr, et. al. teaches about an improved method and apparatus for controlling the temperature of metal strip in a continuous annealing furnace. The known art coverage is not adequate in providing a clear method of operation that can be used or applied to ensure maximum operational efficiency and availability of bogie hearth furnaces. There are references to other type of furnaces and its construction and operation only that cannot be used in the current field of present disclosure.
[0006] Heat treatment of large fabricated parts requires a furnace providing precise temperature control during heating, soaking and cooling so that the desired mechanical properties are achieved throughout the piece and dimensional control (no distortion) is maintained. The use of bogie hearth furnace provides greater flexibility, cost less than vertical furnaces, and is getting very close to matching their technical performance. Accordingly, horizontal bogie hearth furnace (BHF) is one of the simplest methods of heating large steel parts before forging, and of heat-treating bars, plate, castings and forgings.
[0007] However, the problem of maximizing the availability of bogie hearth furnaces along with providing safety in operation needs a new way of placing temperature sensing equipment on the jobs. Also, since job temperature inside the furnace has to be precisely measured during furnace operation along with maintaining correct temperature bandwidth, it insists on using a sturdy yet flexible thermocouples with longer usage life capable of measuring temperatures around 1100 degrees Celsius.
[0008] Therefore, there is a need for improved methods and tools used for operating a horizontal single bogie or a double bogie hearth furnace.

OBJECTS OF THE DISCLOSURE
[0009] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed hereinbelow.
[0010] An object of the present disclosure is to provide a method of placing thermocouples to increase the furnace availability with maximum safety to operators.
[0011] Another object of the present disclosure is to provide a method as described in the preceding paragraph that can be incorporated in all bogie hearth furnaces for ease of placing thermocouples on the jobs of any length before heat treatment.
[0012] Yet another object of the present disclosure is to provide a new method of connecting the thermocouples with lead wires to the recorder for temperature measurement in a bogie hearth furnaces.

SUMMARY
[0013] This summary is provided to introduce concepts related to a method of placing thermocouples on the bogie hearth furnace. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0014] The present disclosure relates to a method of placing thermocouples on the bogie hearth furnace. The method includes making through holes in the bogie wherever temperature of a job has to be measured; firmly positioning a thermocouple positioner through the holes in the bogie such that a major part of the thermocouple positioner stands on the top of the bogie and a minor part of the thermocouple positioner extends below the bogie; firmly positioning thermocouple leads-wires along the length and breadth of the bogie such that all the thermocouples’ lead wires are brought out to one corner of the bogie; and providing plug type connectors between thermocouples and the lead wires, and between lead wires and extension wires;
[0015] In an aspect, the marking of the holes is performed based on the type of system used for maintaining temperature equilibrium inside a furnace chamber.
[0016] In an aspect, in zone-controlled furnaces, the marking of two holes are made per zone on either side bogie.
[0017] In an aspect, the thermocouple positioner is made from a tube material that is able to withstand a maximum operating temperature of the furnace.
[0018] In as aspect, the thermocouple lead-wires are made from material that is able to withstand the maximum surrounding temperature of the furnace.

BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0020] FIG. 1 illustrates a schematic top view of implementation of a method of placing thermocouples in bogie hearth furnace according to an embodiment of the present disclosure; and
[0021] FIG. 2 illustrates an outline side view of implementation of the method of placing thermocouples integrated in the bogie hearth furnace according to an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0022] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0023] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0025] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0027] Embodiments described herein relates to heat treatment of equipment used for power plants namely piping lines, headers, drums, panels, etc., which carry steam and water at high pressure and temperature. Those skilled in the art can appreciate that high alloy steels that are selected for such piping have to be fabricated with close tolerances and with precise metallurgical structure without compromising quality.
[0028] Further, the embodiments described herein are to address the problem of maximizing the utilization of bogie hearth furnaces which are controlled based on job temperature by integrating the job temperature sensing thermocouples in the bogie itself. Such special arrangement calls for thermocouple guides and lead wire guides attached to the bogie itself for a better safety operation. Also, all the lead wires are routed to one corner of the bogie and, with extension wires, the lead wires are connected to the temperature recorder.
[0029] FIG. 1 illustrates a schematic top view of implementation of a method of placing thermocouples in bogie hearth furnace according to an embodiment of the present disclosure. FIG. 2 illustrates an outline side view of implementation of the method of placing thermocouples integrated in the bogie hearth furnace according to an embodiment of the present disclosure.
[0030] This innovative method consists of fixing thermocouples 2 (K – Type) with temperature sensing point 1 on a bogie 4 of a furnace. The thermocouples 2 are fixed in such a way that the job’s temperature is sensed covering the whole furnace heating chamber. As a thumb rule, every furnace zone should contain at least two thermocouples on either side of the bogie 4. Accordingly, holes are through drilled on the bogie 4 and stainless-steel tubes which act as thermocouple guides 3 are inserted and welded with a bogie frame of the bogie 4. At the bottom of the bogie 4, carbon steel tubes which act as thermocouple lead wire guides 5 are welded with the bogie frame along the length and breadth of the bogie 4. After completing an extension lead wire 8 routing, the thermocouples 2 are inserted into their guide tubes. The thermocouples 2 and their corresponding lead wires 8 are numbered and tagged. The thermocouples 2 and the lead wires 8 are plugged using type K thermocouple connector plug 7. Such special connector plug 7 compensates any voltage drop along the line.
[0031] Further, all the extension lines are grouped at one corner of the bogie 4 and are connected to a temperature recorder by recorder extension lines 10 plugged via K-type thermocouple connector plugs 9. The bogie 4 is pulled-out and pushed-in to the furnace chamber using a geared motor drive mechanism connected to its wheels 6.
[0032] During operation, initially, jobs are loaded on the bogie 4 and the temperature sensing tip 1 is firmed on the jobs, and all the plugs 7 are connected and plugs 9 are disconnected and the bogie 4 is moved inside the furnace chamber. After closing the furnace doors and before initiating the firing, all plugs 9 are connected. All the thermocouples are checked for uniformity in reading the furnace room temperature. During the furnace operation, if any of the thermocouples gets bunt-out, it is immediately disconnected from the recorder by unplugging the respective tagged plug 9. After the heat treatment cycle gets completed, the furnace doors are opened and the bogie 4 is pulled outside. The burnt-out thermocouples are replaced by unplugging the respective plug 7. The next cycle can be started immediately without the delay caused by furnace chamber cooling. Furnace operators need not step inside the furnace chamber for placing thermocouples on the jobs as it can be done on the bogie 4 itself keeping it outside in the room temperature.
[0033] Thus, with the implementation of the present disclosure, instant removal and replacement of burn-out thermocouples and instant disconnection of thermocouples are enabled when faulty readings or burn-out are envisaged during furnace operation.
[0034] Further, it will be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its scope.
[0035] Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.
[0036] The above description does not provide specific details of the manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0038] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0039] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

We claim:

1. A method of placing thermocouples on the bogie hearth furnace, the method comprising:
making through holes in the bogie (4) wherever temperature of a job has to be measured;
firmly positioning a thermocouple positioner (3) through the holes in the bogie (4) such that a major part of the thermocouple positioner (3) stands on the top of the bogie (4) and a minor part of the thermocouple positioner (3) extends below the bogie (4);
firmly positioning thermocouple leads-wires (8) along the length and breadth of the bogie (4) such that all the thermocouples’ lead wires (8) are brought out to one corner of the bogie (4); and
providing plug type connectors (7) between thermocouples (2) and the lead wires (8), and between lead wires (8) and extension wires (10);

2. The method as claimed in claim 1, wherein the marking of the holes is performed based on the type of system used for maintaining temperature equilibrium inside a furnace chamber.

3. The method as claimed in claim 2, wherein in zone-controlled furnaces, the marking of two holes are made per zone on either side bogie.

4. The method as claimed in claim 1, wherein the thermocouple positioner (3) is made from a tube material that is able to withstand a maximum operating temperature of the furnace.

5. The method as claimed in claim 1, wherein the thermocouple lead-wires (8) are made from material that is able to withstand the maximum surrounding temperature of the furnace.