Abstract:
Probes, blast furnaces equipped therewith, and methods of fabricating probes. Such a probe includes a base, a shell connected to the base and constructed of at least first and second housing members that extend together along a length of the probe in a longitudinal direction thereof, and at least one support structure interconnecting the first and second housing members. The probe includes a coolant circuit comprising at least one coolant passage within an interior cavity of the shell. The coolant passage has at least one tube supported by the support structure so that the tube contacts at least one of the first and second housing members. At least one sensor is disposed in the second housing member for performing a measurement at an exterior of the shell.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/090,562, filed Dec. 11, 2014, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention generally relates to probes of types used in blast furnaces. More particularly, this invention relates to liquid-cooled above-burden probes of types intended to perform measurements, such as temperature, pressure and/or sampling of gases above burden materials within blast furnaces. 
         [0003]    A blast furnace is a type of metallurgical furnace used to produce a metal from its ore (smelting), for example, iron, etc. In a typical blast furnace, ore, fuel, and flux materials (collectively referred to herein as “burden materials”) are continuously batched through material charging equipment into the upper section of the furnace, while air is supplied through a lower section of the furnace. Chemical reactions take place within the burden materials to produce molten metal (“hot metal”), slag and flue (waste) gases. The molten metal and slag are removed from the lower section of the furnace, whereas before exiting the furnace the flue gases flow through a region of the furnace located above the burden materials, referred to as the throat. 
         [0004]    The contents, processes and reactions within a blast furnace are commonly monitored by probes. As an example, probes located above the burden (hereinafter, above-burden probes) are used in blast furnaces to perform measurements on the flue gases flowing out through the surface of the burden materials and prior to exiting the furnace. Measurements performed by above-burden probes typically include temperature, though other or additional measurements may be performed, for example, pressure measurements, gas sampling, etc. An above-burden probe is typically located within the throat of the furnace, and usually cantilevered into the throat to project along a radial of the furnace. Multiple above-burden probes are often installed so as to be circumferentially spaced along the perimeter of the throat. If equipped to measure temperature, an individual above-burden probe may have multiple temperature sensors located along its length to provide a more detailed picture of the furnace operation. Traditionally, such temperature sensors are metallic sheathed thermocouples, in which the sensing junction of the thermocouple located at the thermocouple tip extends from the probe into the stream of flue gases that has exited the burden material through the surface of the burden material. 
         [0005]    Above-burden probes are often cooled with a liquid coolant, usually water, to extend their lives. A typical construction of a water-cooled above-burden temperature probe comprises a large round pipe or square channel or tube that defines the outermost structure (shell) of the probe, and a central coolant feed pipe that runs the internal length of the probe, extending from the base of the probe (where the probe is mounted to the furnace) to the nose of the probe (disposed at the opposite cantilevered end of the probe). As such, the coolant enters the probe at its base, flows through the central feed pipe to the nose, and then returns to the base through an annular passage defined by and between the feed pipe and shell. With this type of construction, the probe relies on its shell as the containment for the coolant. The construction of an above-burden temperature probe may contain numerous weld joints, each having the potential for being a location at which coolant leakage may occur. In the event of coolant leakage, coolant flow must be stopped such that failure of the probe ultimately follows. 
         [0006]    Thermocouples utilized in above-burden temperature probes are typically installed in a tube or channel that runs through the interior of the probe. Each thermocouple tip protrudes through the wall of the shell, and is therefore in thermal contact with and in close physical proximity to the coolant flowing within the shell. Consequently, the coolant temperature can influence the temperature read by the thermocouple, resulting in a degree of inaccuracy in the flue gas temperature reported by the thermocouple. Another complication is that dust generated within the blast furnace can accumulate on and adhere to the portion of the thermocouple protruding outward from the shell, rendering the thermocouple difficult to remove in the event that it requires replacement. 
         [0007]    Certain drawbacks of conventional above-burden probes relate to their overall construction. High temperatures encountered by a probe ordinarily require a large volume of coolant flow through the probe. Coolant can be a significant contributor to the weight of a probe having a coolant circuit in which the coolant flows through a central feed pipe and then through an annular passage defined by a void between the feed pipe and probe shell, such that the coolant fills the entire interior cavity within the probe shell. The wall thickness of the shell must be increased to support the additional weight of the coolant, further adding to the overall weight of a probe and the structural demands associated with being cantilevered from the furnace wall. Cooling and structural requirements tend to result in probes whose shells are constructed from round pipes or square tubes, which present a relatively large obstruction to burden material being added to a furnace by the material charging equipment located above the probe. A large obstruction has the potential to significantly disrupt the distribution of the burden material charged into the furnace. 
         [0008]    In view of the above, it should be appreciated that there are various shortcomings associated with conventional above-burden probe designs, and that overcoming one or more of these shortcomings would have the potential to improve the reliability and life of a probe and promote the overall operation of a blast furnace. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0009]    The present invention provides probes suitable for performing measurements within a blast furnace. A particular embodiment is a liquid-cooled above-burden probe that is suitable for performing measurements on gases above the burden materials within a blast furnace. 
         [0010]    According to one aspect of the invention, a probe includes a base, a shell connected to the base and constructed of at least first and second housing members that extend together along a length of the probe in a longitudinal direction thereof and define an interior cavity therebetween and between the base and a nose of the shell, and support structures interconnecting the first and second housing members. At least one of the support structures is disposed within the interior cavity of the shell. The probe further includes a coolant circuit comprising at least one coolant passage within the interior cavity of the shell. The coolant circuit extends along the length of the probe for cooling the shell, and the coolant passage is defined by at least a first tube supported by at least one of the support structures so that the first tube contacts at least one of the first and second housing members. At least one sensor is disposed in at least the second housing member for performing a measurement at an exterior of the shell. 
         [0011]    Other aspects of the invention include method of fabricating a probe comprising the elements described above and blast furnaces equipped with a probe comprising the elements described above. 
         [0012]    Technical effects of this invention include various design, construction and fabrication aspects capable of promoting the reliability, life, and/or operational performance of an above-burden probe. Certain technical effects may include one or more of the following: addressing structural causes of probe failure, addressing structural influences that contribute to measurement inaccuracies, and reducing the profile of a cantilevered probe with the potential for simultaneously promoting its strength. 
         [0013]    Other aspects and advantages of this invention will be further appreciated from the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  schematically represents a side view of an above-burden probe installed in the throat of a blast furnace in accordance with a nonlimiting embodiment of the invention. 
           [0015]      FIGS. 2, 3 and 4  are perspective, side and end views, respectively, of the probe of  FIG. 1 . 
           [0016]      FIGS. 5 and 6  represent cross-sectional views of the probe of  FIGS. 1 through 4  along lines  5 - 5  and  6 - 6 , respectively, of  FIG. 4 . 
           [0017]      FIG. 7  is a detail of the cross-sectional view of the probe in  FIG. 5 . 
           [0018]      FIGS. 8, 9, 10 and 11  represent cross-sectional views of the probe of  FIGS. 1 through 7  along lines  8 - 8 ,  9 - 9 ,  10 - 10 , and  11 - 11 , respectively, of  FIG. 3 . 
           [0019]      FIG. 12  represents a cross-sectional view of the probe of  FIGS. 1 through 11  along line  12 - 12  of  FIG. 4 . 
           [0020]      FIG. 13  is a detail of the cross-sectional view of the probe in  FIG. 12 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIGS. 1 through 13  represent various views of one embodiment of an above-burden probe  10  encompassing certain aspects of the invention. The drawings disclose certain aspects for the various components of the probe  10  that are believed to be preferred or exemplary, but are otherwise not necessarily limitations to the scope of the invention. 
         [0022]    In  FIG. 1 , the probe  10  is shown installed in a wall  12  that surrounds and defines a throat of a blast furnace. The probe  10  is adapted for measuring one or more aspects and/or properties of flue gases flowing upward from a burden material (not shown) below the probe  10  and then through the throat prior to exiting the furnace. The probe  10  will be described in reference to measuring temperature, though other or additional measurements may be performed, for example, pressure measurements, gas sampling, etc. 
         [0023]    To facilitate the description provided below of the embodiment represented in the drawings, relative terms, including but not limited to, “vertical,” “horizontal,” “lateral,” “front,” “rear,” “side,” “forward,” “rearward,” “upper,” “lower,” “above,” “below,” “right,” “left,” etc., may be used in reference to the orientation of the probe  10  generally as installed in a blast furnace as shown in  FIG. 1 , and therefore are relative terms that indicate the preferred construction, installation and use of the invention, but should not be otherwise interpreted as limiting the scope of the invention. The probe  10  is shown as being cantilevered into the throat and preferably projects along a radial of the furnace. The probe  10  may be one of any desired number of above-burden probes that might be installed in the throat. 
         [0024]    The probe  10  is cooled with a liquid coolant, for example, water, that flows through a coolant circuit within the probe  10 . As will be discussed in greater detail below, the coolant circuit preferably runs nearly the entire internal longitudinal length of the probe  10 , extending from a base  14  of the probe  10  (used to secure the probe  10  to the furnace wall  12 ) to a nose  16  of the probe  10  disposed at the opposite cantilevered end of the probe  10 . The outermost structure of the probe  10  is defined by a shell  18 . A preferred construction of the probe  10  is represented in  FIGS. 4 and 8 through 11  as including weld joints  26 . However, in contrast to prior art probes of the type described previously, the probe  10  does not rely on the shell  18  as the containment for the coolant, and therefore the weld joints  26  are not required to be liquid-tight. Furthermore, the weld joints  26  are shown as disposed on the lateral sides of the probe  10 , and therefore have reduced exposure to burden materials being charged into the furnace from above the probe  10  and hot gases flowing upward from the burden materials below the probe  10 . 
         [0025]    For the purpose of measuring temperature, the probe  10  is represented in  FIG. 1  as having multiple temperature sensors  20  located along its longitudinal length that protrude through the shell  18  of the probe  10 . The temperature sensors  20  may be of any suitable type, though are preferably consistent with the description below in reference to  FIGS. 12 and 13 . As will be discussed, the sensors  20  preferably make use of thermocouples whose tips (sensing junctions)  48  do not extend from the probe  10  in a manner that directly exposes the thermocouple tips  48  to the stream of flue gases within the furnace. 
         [0026]    The general construction of the probe  10  will be described in reference to  FIGS. 1 through 11 . As represented in  FIGS. 4 and 8 through 11 , a preferred construction of the probe shell  18  utilizes two housing members  22  and  24  that extend essentially the entire length of the probe  10  to define the shell  18  and an interior cavity within the shell  18 . As will be apparent from  FIGS. 4 and 8 through 11 , each housing member  22  and  24  can be fabricated from a structural angle initially having an L-shaped cross section, but with one leg bent as shown such that the shell  18  formed by the housing members  22  and  24  has a six-sided polygonal cross-sectional shape. As a result of the housing members  22  and  24  being joined edge to edge in a clamshell-like manner as shown in  FIG. 4 , the upper side of the shell  18  is entirely defined by the housing member  22  and the lower side of the shell  18  is entirely defined by the housing member  24 . In a current embodiment, the members  22  and  24  are fabricated from ASTM A572, though it is foreseeable that other materials could be used. The housing members  22  and  24  are secured to each other (and to the coolant circuit) through combinations of the weld joints  26  and support plates  28 ,  30  and  32  represented in  FIGS. 4 and 8 through 11 . The support plates  28  and  32  generally close the opposite ends of the shell  18  at its base  14  and nose  16 , respectively, whereas the support plates  30  support the housing members  22  and  24  from within the interior cavity of the shell  18 . Though the support plates  28 ,  30  and  32  are referred to herein as “plates,” it should be understood that this term is not intended to suggest a limitation on shape in that a wide variety of support structures capable of providing the support function described herein could foreseeably be used as any one or more of the plates  28 ,  30  and  32 . 
         [0027]      FIGS. 4 and 8 through 11  further represent components of the coolant circuit, of which further details can be seen in  FIGS. 5 through 7 . The embodiment of the coolant circuit shown in the figures comprises two separate coolant passages that are fluidically isolated within the probe  10 . A first of the coolant passages is defined by two tubes  34  that are spaced vertically within the shell  18  and fluidically interconnected by a coupling  36  near the nose  16  of the shell  18  ( FIG. 5 ). The second passage is defined by two tubes  38  that are spaced horizontally within the shell  18  and fluidically interconnected by a coupling  40  located near the shell nose  16  ( FIG. 6 ), with the coupling  36  being between the coupling  40  and the support plate  32  at the nose  16  of the shell  18  ( FIG. 7 ). The tubes  34  and  38  and couplings  36  and  40  are represented as having rectangular cross-sections, though other shapes are foreseeable. As seen in  FIG. 4 , the first coolant passage defined by the tubes  34  has two ports  42  located in the support plate  28  that serve as an inlet and outlet to the first coolant passage, and the second coolant passage defined by the tubes  38  has two ports  44  located in the housing members  22  and  24  that serve as an inlet and outlet to the second coolant passage. As evident in  FIGS. 8 through 11 , the tubes  34  and  38  are in thermal conductive contact with the housing members  22  and  24  so that the coolant within the tubes  34  and  38  serves to cool the probe shell  18  formed by the members  22  and  24 . Thermal contact between the tubes  34  and  38  and members  22  and  24  can be promoted through thermally conductive shims  46 , as nonlimiting examples, formed of brass or copper. As shown in  FIGS. 8 through 10 , the tubes  34  and  38  are supported within the shell  18  by the support plates  30 , which also serve to maintain thermal conductive contact between the tubes  34  and  38 , shims  46 , and housing members  22  and  24 . The support plates  30  are represented as being generally X-shaped to define four legs that extend in diagonal directions, with the tubes  34  nested between the legs on the upper and lower sides of each plate  30  and the tubes  38  nested between the legs on opposite lateral sides of each plate  30 . 
         [0028]    As noted above, the temperature sensors  20  are thermocouples, each having a sensing element (junction) located at the thermocouple tip  48  ( FIGS. 12  and  13 ). The thermocouple tips  48  preferably do not extend from the probe  10  in a manner that would directly expose the tips  48  to the stream of flue gases within the furnace. As such, dust generated within the blast furnace cannot accumulate on or adhere to the thermocouple tips  48 , and therefore does not interfere with the ability to remove a sensor  20  in the event it requires replacement. In addition, the thermocouple tips  48  are not in direct physical contact with the coolant flowing within tubes  34  and  38  of the coolant circuit, so that the coolant temperature has a reduced influence on the temperatures read by the sensors  20 . The sensors  20  are depicted in  FIGS. 12 and 13  as sheathed thermocouples which contain sensing junctions within their tips  48  and interconnecting wiring to the sheathed thermocouple base located outside of the probe  10 . The sheathed thermocouples are inserted through tubes  50  supported by the support plates  28  and  30 . As evident from  FIGS. 8-10 , the tubes  50  can pass through openings in the legs of the plates  30 , such that the tubes  50  are arranged within the probe  10  to define an X-shaped pattern as evident from  FIGS. 4 and 8 through 10 . The thermocouple tips  48  of the sensors  20  are embedded in a well  52  attached to the housing member  24 , but separated therefrom by a thermal insulating gasket  54  to reduce the influence that the housing member  24  (cooled by the coolant tubes  34  and  38 ) will have on temperatures sensed by the sensors  20 . Additionally, from  FIGS. 8 through 11  it can be seen that the wells  52  are mounted to portions of the housing member  24  that are between portions of the plate  24  that are in contact with the coolant tubes  34  and  38 , such that the plate  24  is immediately between the tips  48  and a portion of the interior cavity of the shell  18  that contains a gas (e.g., air, flue gases, etc.). This arrangement further separates the thermocouple tips  48  from the coolant to reduce the influence that the coolant will have on temperatures sensed at the tips  48 . 
         [0029]    As discussed above, each of the tubes  34  and  38  of the coolant circuit is nested between the legs on one of the upper, lower and lateral sides of each plate  30 . As a result, each tube  34  and  38  is also disposed between legs of an X-shaped pattern defined by the sensor tubes  50 , so that the tubes  34  are on opposite vertical sides of the X-shaped pattern and the tubes  38  are also on opposite horizontal sides of the X-shaped pattern. The result is a symmetrical arrangement of internal components within the cavity of the shell  18 . 
         [0030]    In addition to the operational advantages summarized above, the overall construction of the probe  10  provides structural advantages. Though high temperatures encountered by the probe  10  may require a large volume of coolant flow through the tubes  34  and  38 , the tubes  34  and  38  account for only a fraction of the total volume of the interior cavity of the shell  18  (typically less than half, e.g., about 20%), and therefore the volume of coolant required by the probe  10  can be considerably less in comparison to conventional probes whose interiors are completely filled with coolant. As such, the coolant within the probe  10  contributes much less to the weight of the probe  10 , and the wall thickness of the shell  18  can be less than that of conventional probes. 
         [0031]    The profile of the probe  10  can also be less than that of conventional probes having round or rectangular-shaped cross-sections, and therefore present a relatively smaller obstruction to burden material being added to the furnace. In particular, the cross-section of the probe  10  in the horizontal direction can be seen in  FIGS. 8 through 10  to be less than (roughly two-thirds) the vertical direction. 
         [0032]    The welded construction, which results from the housing members  22  and  24  being fabricated from structural angles to create a six-sided polygonal cross-sectional shape for the shell  18 , is also believed to be stronger and more rigid in the vertical direction than a conventional probe having a round or rectangular-shaped cross-section. The clamshell-like manner in which the housing members  22  and  24  are joined is also structurally advantageous since the upper and lower sides of the shell  18 , which are directly subjected to burden materials being charged into the furnace and hot gases flowing upward from the burden materials below the probe  10 , are entirely defined by either the housing member  22  or the housing member  24 . The construction of the shell  18  from housing members  22  and  24  that extend together along the length of the probe  10  also facilitates the assembly of the probe  10 , including the placement of the coolant circuit, sensors, tubes, and other internal components of the probe  10 . 
         [0033]    Finally, the embodiment of the probe  10  shown in the figures includes protective plating  56  attached to the upper housing member  22 , and therefore serves to provide additional protection to the shell  18  from damage by burden materials being charged into the furnace from above the probe  10 . The plating  56  is shown as having a shingled arrangement, with the distal edge of a plating  56  (i.e., the edge farthest from the furnace wall  12 ) overlapping the proximal edge of the next plating  56  located distally from the overlapping plating  56 . Shingling of the plating  56  in this manner serves to promote the flow of burden materials over the upward-facing surfaces of the plating  56 , protecting the probe shell  18  from exposure to the burden materials. 
         [0034]    While the invention has been described in terms of a specific embodiment, it is apparent that other forms could be adopted by one skilled in the art. For example, the probe  10  could differ in appearance and construction from the embodiment shown in the Figures, the functions of each component of the probe  10  could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function, and various processes and materials could be used in the construction of the probe  10  and its components. Accordingly, it should be understood that the invention is not limited to the specific embodiment illustrated in the Figures. It should also be understood that the phraseology and terminology employed above are for the purpose of disclosing the illustrated embodiment, and do not necessarily serve as limitations to the scope of the invention. Therefore, the scope of the invention is to be limited only by the following claims.