Abstract:
A steel reheat furnace and method of use thereof are disclosed. The furnace includes a housing defining an interior furnace space that is substantially sealed from the environment. A carbon monoxide atmosphere is placed in the interior furnace space for enveloping the steel and protecting it from oxidation. Oxidation of the carbon monoxide generates heat that reheats the steel for later rolling into rolled steel. Flue gases are removed from the furnace by a furnace hood and flue system. The steel advances through the furnace by a roller system driven by frictional force.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuing application of co-pending U.S. patent application Ser. No. 09/610,842, filed Jul. 5, 2000, entitled “Process and Apparatus for Generating Carbon Monoxide and Extracting Oil from Oil Shale,” which is hereby incorporated herein by reference in its entirety. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    The present invention relates generally to steel production, and more particularly, but not necessarily entirely, to a steel heating furnace with particular use in reheating previously cast steel.  
           [0004]    In the steel making industry, it is known to produce steel and store it in slabs in sizes required by the provider. This is often accomplished by (i) dispensing newly formed steel from a continuous caster in the form of slabs, during which the steel slabs unavoidably cool to a temperature below the desired working temperature of the steel, (ii) feeding the slabs of steel through a reheat furnace to thereby heat the steel slab to a working temperature, and then (iii) compressively rolling the steel slabs into a reduced thickness. This type of steelmaking system is thus summarized briefly as comprising a caster, reheat furnace, and roll line, utilized in sequence in that order.  
           [0005]    A newly cast continuous slab of steel is initially quite thick as it is dispensed from the caster. The slab might for example be 25.4 cm (10 inches) thick. Although the steel has a temperature of perhaps 815° C. (1500° F.) when it is dispensed from the caster, it generally requires a working temperature maintained above 982° C. (1800° F.) while it is rolled into the desired thickness. Naturally, the hotter the steel, the easier it can be rolled, such that a temperature of 2200° F. is preferred. The newly cast steel slab can either be stored somewhere to be reheated and rolled later, or it can be heated immediately to the higher working temperature and rolled right after casting. Naturally, less energy is required to heat the steel slab from 815° C. (1500° F.) to a working temperature above 982° C. (1800° F.) directly after casting than would be required if the steel is stored temporarily after casting and allowed to cool to ambient temperature prior to rolling. It is therefore desirable, in steel casting operations, to utilize the caster, reheat furnace, and roll line in direct succession.  
           [0006]    It is futile to attempt to roll steel unless the slab of steel is heated to a working temperature well above 982° C. (1800° F.), such that the temperature of all portions of the steel is maintained above 982° C. (1800° F.). When the steel slab is heated to the working temperature, it is fed through the rollers in the roll line, which roll and compress the steel to a reduced thickness using roll line machinery and processes known to those having ordinary skill in the field. For example, a slab of steel cast at 25.4 cm (10 inches) thick can be reheated and rolled to a reduced thickness of 0.16 cm (1/16 of an inch) or thinner.  
           [0007]    Several attempts have been made to construct a steel heating furnace that works efficiently. Many such attempts are described in the following U.S. patents, which are incorporated herein by reference: U.S. Pat. No. 1,539,833; U.S. Pat. No. 1,791,166; U.S. Pat. No. 1,833,132; U.S. Pat. No. 2,883,172; U.S. Pat. No. 2,929,614; U.S. Pat. No. 3,770,103; U.S. Pat. No. 4,243,378; U.S. Pat. No. 5,441,407; and U.S. Pat. No. Re. 19,205.  
           [0008]    The known steel reheat furnaces generally burn natural gas or a hydrocarbon fuel within the furnace to provide the heat. The gas or fuel combusts to form super-heated water vapor and carbon dioxide. The water vapor reacts with the steel to form a magnetic iron oxide (Fe 3 O 4 ) on the surface of the steel being reheated, in the form of an undesirable crusty, abrasive surface scale. The iron oxide scale must be removed before rolling, otherwise, the iron oxide scale becomes rolled right into the steel surface during rolling and becomes a defect in the steel, such defects sometimes being referred to as “pits.” Sometimes slivers of the iron oxide are rolled into the steel.  
           [0009]    The prior art reheat furnaces are not sealed from the atmosphere, and in fact have openings along their sides. To prevent the gas-burning flames from venturing through the open sides and outside the furnace, a pressure monitoring system is utilized in which the pressure within the furnace matches the surrounding atmospheric pressure. This pressure matching system of operation, when utilized in a reheat furnace having side openings, carries the risk of leaking some gas into the atmosphere because the matching pressure varies and therefore cannot be completely reliable.  
           [0010]    Common types of reheat furnaces include a “pusher furnace,” a “walking beam” furnace, and a “roller hearth” or “tunnel” furnace. In the walking beam furnaces and in the pusher-type furnaces there is a high degree of surface contact of the steel slabs with the slab supports, particularly in the pusher-type furnaces. Such surface contact causes the slab supports to absorb heat from the steel, often undesirably scoring the slab and producing “cold spots” on the steel slab. These cold spots can result in an inconsistent thickness in the rolled steel. Although the conventional roller hearth type furnace has the advantage of uniformly heating the steel slabs without damaging or marking the surface, it also has the disadvantage of causing excessive heat loss, and the rollers are highly expensive.  
           [0011]    The prior art reheat furnaces are thus characterized by several disadvantages that are addressed by the present invention. The present invention minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.  
           [0012]    In view of the foregoing, it will be appreciated that a steel heating furnace that can significantly reduce oxidation of the surface of the steel, and provide for a controlled atmosphere during reheating, and reduce cold spots and thus increase the consistency of thickness of rolled steel, and improve efficiency of reheating steel, and avoids damaging or marking the surface of the steel, would be a significant advancement in the art.  
         BRIEF SUMMARY OF THE INVENTION  
         [0013]    It is therefore an object of the present invention to provide a steel heating furnace that is simple in concept.  
           [0014]    It is another object of the present invention to provide such a steel heating furnace that minimizes the occurrence of iron oxide forming in the surface of the steel.  
           [0015]    It is a further object of the present invention, in accordance with one aspect thereof, to provide a steel heating furnace in which the use of hydrocarbon fuel, such as natural gas, is avoided during operation.  
           [0016]    It is an additional object of the present invention, in accordance with one aspect thereof, to provide a steel heating furnace in which the occurrence of water vapor within the furnace is minimized.  
           [0017]    It is yet another object of the present invention, in accordance with one aspect thereof, to provide a steel heating furnace in which a carbon monoxide atmosphere is maintained within the furnace during operation.  
           [0018]    It is a still further object of the present invention, in accordance with one aspect thereof, to provide a steel heating furnace capable of enabling steel to be heated with an unoxidized finish.  
           [0019]    It is an additional object of the present invention, in accordance with one aspect thereof, to provide a steel heating furnace in which steel within the furnace is more evenly heated.  
           [0020]    The above objects and others not specifically recited are realized in a specific illustrative embodiment of a steel heating furnace, comprising:  
           [0021]    a furnace housing for receiving steel thereinto, the furnace housing defining an interior furnace space;  
           [0022]    means for heating the interior furnace space and the steel residing within the furnace; and  
           [0023]    means for supplying carbon monoxide into the interior furnace space and maintaining a carbon monoxide atmosphere within the interior furnace space.  
           [0024]    Another illustrative embodiment of the invention comprises:  
           [0025]    a furnace housing for receiving steel thereinto, the furnace housing defining an interior furnace space;  
           [0026]    means for heating the interior furnace space and the steel residing within the furnace; and  
           [0027]    means for substantially sealing the furnace housing from the atmosphere.  
           [0028]    Still another illustrative embodiment of the invention comprises:  
           [0029]    a furnace housing for receiving steel thereinto, the furnace housing comprising sides, an entrance, and an exit opening, and wherein the furnace housing is sealed along its sides from the atmosphere and defines an interior furnace space;  
           [0030]    means for heating the interior furnace space and the steel residing within the furnace; and  
           [0031]    means for blocking the entrance and the exit opening of the furnace housing from the atmosphere to inhibit the entry of ambient air into the furnace housing.  
           [0032]    Yet another illustrative embodiment of the invention comprises:  
           [0033]    a furnace housing for receiving steel thereinto, the furnace housing having sides and defining an interior furnace space;  
           [0034]    means for heating the interior furnace space and the steel residing within the furnace; and  
           [0035]    rollers rotatably disposed within the furnace housing for supporting steel thereupon, wherein the rollers are fully confined within the furnace housing without extending beyond the sides of the furnace.  
           [0036]    A still further illustrative embodiment of the invention comprises:  
           [0037]    a furnace housing for receiving steel thereinto, the furnace housing defining an interior furnace space;  
           [0038]    means for heating the interior furnace space and the steel residing within the furnace; and  
           [0039]    a plurality of support roller means rotatably disposed within the furnace housing for supporting steel thereupon, wherein each support roller means comprises a series of spaced-apart, co-axial wheels.  
           [0040]    Another illustrative embodiment of the invention comprises:  
           [0041]    a furnace housing for receiving steel thereinto, the furnace housing defining an interior furnace space;  
           [0042]    means for heating the interior furnace space and the steel residing within the furnace;  
           [0043]    a plurality of support roller means rotatably disposed within the furnace housing for supporting steel thereupon; and  
           [0044]    a plurality of stabilizer roller means disposed beneath, and in alignment with, the roller means, respectively.  
           [0045]    Still another illustrative embodiment of the invention comprises a steel heating furnace, comprising:  
           [0046]    a furnace housing for receiving steel thereinto, the furnace housing having sides and defining an interior furnace space;  
           [0047]    means for heating the interior furnace space and the steel residing within the furnace; and  
           [0048]    support rollers rotatably and removably disposed within the furnace housing for supporting steel thereupon, such that said rollers are interchangeable.  
           [0049]    Yet another illustrative embodiment of the invention comprises:  
           [0050]    a furnace housing for receiving steel thereinto, the furnace housing having sides and defining an interior furnace space;  
           [0051]    means for heating the interior furnace space and the steel residing within the furnace;  
           [0052]    support rollers rotatably disposed within the furnace housing for supporting steel thereupon; and  
           [0053]    advancing means for advancing steel through the furnace housing without imparting a direct torsion driving force to the support rollers. As used herein, “direct torsion driving force” means the force imparted by direct attachment to a driven member, such as a belt or chain, by means of a sprocket, pulley, or the like. In the present invention, the support rollers are “floating,” meaning that such support rollers are not driven via a sprocket, pulley, or similar component, but instead are driven only by frictional force transferred from another moving component of the system, such as the steel belt.  
           [0054]    A still further illustrative embodiment of the invention comprises:  
           [0055]    (a) placing the steel in a steel heating furnace such that the steel is enveloped in a carbon monoxide atmosphere; and  
           [0056]    (b) oxidizing a portion of the carbon monoxide atmosphere, thereby generating heat and reheating the steel.  
           [0057]    Another illustrative embodiment of the invention comprises:  
           [0058]    (a) placing the steel in a steel heating furnace comprising  
           [0059]    a furnace housing for receiving steel thereinto, the furnace housing having sides and defining an interior furnace space;  
           [0060]    means for heating the interior furnace space and the steel residing within the furnace;  
           [0061]    support rollers rotatably disposed within the furnace housing for supporting steel thereupon;  
           [0062]    advancing means for advancing steel through the furnace housing without imparting a direct torsion driving force to the support rollers  
           [0063]    (b) heating the interior furnace space and the steel placed therein; and  
           [0064]    (c) advancing the steel through the furnace housing by imparting frictional driving force to the support rollers, which then impart frictional driving force to the steel.  
           [0065]    Still another illustrative embodiment of the invention comprises:  
           [0066]    (a) placing the steel in a steel heating furnace comprising:  
           [0067]    a furnace housing for receiving steel thereinto, the furnace housing having sides and defining an interior furnace space;  
           [0068]    means for heating the interior furnace space and the steel residing within the furnace;  
           [0069]    support rollers rotatably disposed within the furnace housing for supporting steel thereupon; and  
           [0070]    a hearth defining a floor of the interior furnace space configured for partially shielding the support rollers from heat contained in the interior furnace space;  
           [0071]    (b) heating the interior furnace space and the steel placed therein; and  
           [0072]    (c) advancing the steel through the furnace housing by causing the support rollers to rotate, thereby imparting frictional driving force to the steel.  
           [0073]    Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by the practice of the invention without undue experimentation. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.  
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0074]    The above and other objects, features and advantages of the invention will become apparent from a consideration of the subsequent detailed description presented in connection with the accompanying drawings in which:  
         [0075]    [0075]FIG. 1 shows a perspective view of a steel heating furnace according to the present invention;  
         [0076]    [0076]FIG. 2 shows a perspective, break-away view of a portion of the furnace of FIG. 1 proximal to the entrance opening;  
         [0077]    [0077]FIG. 3 shows a side sectional view of a portion of the furnace of FIG. 1 proximal to the entrance opening;  
         [0078]    [0078]FIG. 4 shows another perspective cut-away view of a portion of the furnace of FIG. 1 proximal to the entrance opening, showing the belt drum, two sealing drums, and rollers mounted on axles;  
         [0079]    [0079]FIG. 5 shows another perspective cut-away view of the furnace of FIG. 1 showing the belt drum and belt, two sealing drums, rollers, roller heat shield, and axles;  
         [0080]    [0080]FIG. 5A shows a frontal view of a support roller of the furnace of FIG. 1;  
         [0081]    [0081]FIG. 6 shows a side view schematic diagram of the gas header systems used in connection with the furnace of FIG. 1;  
         [0082]    [0082]FIG. 7 shows a preferred embodiment of a steel heating furnace, made in accordance with the principles of the present invention, and which is an alternative embodiment to the steel heating furnace of FIG. 1;  
         [0083]    [0083]FIG. 8 shows an open view of an alternative embodiment of the furnace of FIG. 5, revealing support-roller refractories and a furnace housing at the flue-gas exhaust area; and  
         [0084]    [0084]FIG. 9 is a perspective, under-side view of the furnace of FIG. 8.  
     
    
     DETAILED DESCRIPTION  
       [0085]    For the purposes of promoting an understanding of the principles in accordance with the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the invention as illustrated herein, which would normally occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention claimed.  
         [0086]    Referring now to FIGS. 1 and 2, there is shown an illustrative embodiment of the present invention. The steel heating furnace  10  comprises an elongate furnace housing  12  defining an interior space  13  into which steel slabs  15  to be reheated are received. The housing has an entrance opening  14  through which the steel slabs  15  enter the furnace  10 , ranging from ambient temperature to about 815° C. (1500° F.), and an exit opening  16  through which the reheated steel slab  15  exits the furnace  10  at a temperature of 200-400° F. above the critical working temperature of 982° C. (1800° F.), and preferably at about 1204° C. (2200° F.). The housing comprises a top  18  and sides  20 ,  22  that assist in sealing the interior space of the furnace  10  from the exterior atmosphere. Preferably, the top and sides of the housing are removable at some points, such that waste materials from the interior of the furnace  10  can be removed easily, and also to facilitate maintenance of the furnace  10 , when necessary. Preferably, the housing is well insulated to retain heat in the furnace  10 , thereby assisting in making the reheating process more efficient. Insulation material  23  resides in the top  18  of the housing as illustrated in FIG. 3. Insulation material  23  is also placed in the sides  20 ,  22 . Disposed in the top  18  is at least one furnace hood  24  for collecting gases and channeling them out of the furnace  10 . A plurality of hoods  24  are preferably formed in the furnace  10  as shown. A flue  26  is disposed on each hood  24  for conducting these gases out of the furnace  10 . This hood system reduces and preferably eliminates leakage of furnace gases into the environment. Also disposed in the top  18  is at least one carbon monoxide header  28  for conducting carbon monoxide into the interior space and at least one air header or oxygen header  30  for conducting preferably oxygen into the interior space. The header  30  may be referred to broadly in the claims as an air header, to signify that any suitable air mixture may be conveyed therethrough, although pure oxygen is preferred. These headers will be described in more detail below. Located below the entrance opening is a belt drum  32  for driving a continuous steel belt  34 , for conducting the steel slabs  15  through the interior space  13 . The belt drum is driven by a power drive, which can be of any conventional type. Located at the entrance opening  14  is a curtain  36 , which hangs from the top  18  of the housing  12 , to minimize exposure of the interior of the furnace  10  to atmosphere. A pair of sealing drums  38 ,  40  are also disposed at the entrance opening for working in cooperation with the curtain  36  for sealing the interior space of the furnace  10  from the exterior environment. The curtain  36  is flexible for permitting a steel slab to pass through the entrance opening  14 . Once the steel slab  15  has entered the interior space of the furnace  10 , the curtain hangs such that a bottom portion thereof contacts the sealing drum  38  for sealing the entrance opening. It will be apparent that the sealing drum  38  is disposed beneath the curtain  36  for this cooperative sealing of the entrance opening to occur. Sealing drums  38  and  40  are disposed such that their cylindrical axes are approximately horizontal, approximately parallel to each other, and generally vertically aligned. The steel belt  34  passes around the belt drum  32  and between sealing drums  38  and  40 .  
         [0087]    Additional details of the furnace  10  are shown in FIGS.  3 - 5 . The floor of the interior space  13  is provided by a heat-shield hearth  42 , which comprises a generally planar member having slots  44  formed therein. Beneath the hearth is disposed a plurality of support rollers  46  mounted on axles  47  disposed generally perpendicularly to the direction of travel of the steel slab. The axles  47  are disposed on side supports  49 , such that the axles  47  and rollers  46  are removably disposed within the furnace housing  12  for supporting the slab  15  thereupon, such that said rollers  46  are interchangeable. The axles  47  are preferably rotatably disposed in support blocks  51  and the ends of the axles  47 , and the support block  51  is removably placed in the side supports  49 .  
         [0088]    Multiple support rollers  46  are disposed in a spaced-apart configuration on each axle  47 . The support rollers protrude upward through the slots  44  in the heat-shield hearth  42 . Thus, the instant furnace  10  is of the roller hearth type. The steel slab rests on these support rollers  46  as the slab is transported through the furnace  10 . Beneath each support roller  46  is disposed a “back up roller,” also referred to as a stabilizer roller  48  for providing support for the support roller  46 , which in turn supports the weight of the steel slab. These stabilizer rollers  48  ultimately carry the load of the steel slab, eliminate warping of the support rollers  46 , and maintain alignment of the hearth rolling plane. The belt  34  passes between the support rollers  46  and stabilizer rollers  48 . The support rollers  46  rotate on the axles  47 , and such rotation is preferably driven by friction between the support rollers  46  and the belt  34 . That is to say that there is preferably no direct drive mechanism disposed on the support rollers for causing the support rollers to rotate.  
         [0089]    The hearth helps to hold heat in the interior space and also tends to seal the bottom of the interior space for holding a controlled atmosphere in the interior space. The space beneath the hearth comprises a cool space  50  in which the axles, stabilizer rollers, and belt are disposed. The temperature in this cool space is lower than in the interior space of the furnace  10 . Thus, the useful life of components that reside in the cool space is prolonged because of the lower temperature at which they operate in the cool space in comparison to the higher temperatures in the interior furnace space. Moreover, this shielding of the support rollers from the high temperatures of the interior space of the furnace  10  permits construction from less expensive heat resistant alloys, thereby reducing maintenance and construction costs. One or more belt rollers or idlers  52  may be disposed at selected locations beneath the return belt for supporting the belt and minimizing sagging thereof.  
         [0090]    Referring again to FIG. 1, at the exit opening end of the furnace  10 , there is another belt drum  54  around which the continuous belt  34  is disposed. Since it is desirable to seal the interior space for maintaining a controlled atmosphere therein, there is another curtain (not shown), similar to the curtain  36  located at the entrance opening, disposed at the exit opening for permitting the reheated steel slab to exit the furnace  10  while sealing the interior space of the furnace  10  at other times. This curtain is made of a flexible, heat resistant material. It will be appreciated that references to “substantially sealing the interior space of the furnace  10  from atmosphere” shall refer broadly to the concept of a furnace  10  that is sealed sufficient to retain a large amount of the sensible heat produced from the casting operation, permitting that heat to be utilized for metal rolling operations that occur after the reheating operation in the furnace  10 .  
         [0091]    There are also two sealing rollers, similar to the sealing rollers  38  and  40  at the entrance of the furnace  10 , located at the exit of the furnace  10 . In addition, there is an idler roller located at the exit of the furnace that corresponds with, and is similar to, the drive roller  32  at the entrance, and this exit idler roller shall preferably be fashioned such that it is moveable with respect to the belt  34 , thus enabling the tension of the belt  34  to be adjusted.  
         [0092]    As a partial summary, it will be appreciated that cast materials can flow directly and smoothly from a slab caster to the reheat furnace  10  without exposure to atmospheric cooling or oxidation, without the need for other equipment to accomplish this outcome, by utilizing the structural features described herein as may be appreciated by one of ordinary skill in the field. The furnace  10  may include a sealed shell, and the operation of the hoods  24  help prevent furnace gas leakage into the atmosphere. The furnace  10  is preferably constructed, in accordance with the above description, and accompanied by any further suitable structure sufficient to allow the flue gas to flow longitudinally within the furnace  10  with the steel slab  15 . The rollers  46  are shielded by the heat-shield hearth  42  to minimize exposing the rollers  46  to the heat of the furnace  10 , permitting the rollers  46  to be made from low cost heat resistant alloys, which further reduces maintenance and construction costs. The rollers  46  have less contact with the surface of the slab  15  than their prior counterparts (cylindrical rollers), thereby reducing heat transfer and eliminating cold areas in the slabs. The top and sides of the housing  12  are removable at some points, such that waste materials from the interior of the furnace  10  can be removed easily, and also to facilitate maintenance of the furnace  10 , when necessary. Beneath each support roller  46  is disposed a stabilizer roller  48  for providing support for the support roller  46 , which helps prevent the support roller axles from warping and maintains alignment of the hearth rolling plane. The furnace  10  preferably has the capability to adequately heat steel slab castings and also to reduce slab casting surface oxides to metallics to achieve excellence in surface malleability and ductility to thereby produce a highly smooth skin quality, utilizing any suitable structure and features for accomplishing the same as known to those having ordinary skill in the field.  
         [0093]    [0093]FIG. 6 shows a side schematic view of illustrative apparatus for feeding gases into the interior space of the furnace  10  for controlling the atmosphere within the interior space. As described above, a carbon monoxide header  28  and an oxygen header  30  are disposed on the top  18  of the housing. The carbon monoxide header  28  comprises a pipe for conducting carbon monoxide gas into the interior space  13 . The carbon monoxide header  28  further comprises a plurality of distribution pipes  56  spaced apart in a generally horizontal configuration and descending into the interior space  13 . The distribution pipes  56  end in nozzles  58  for delivering carbon monoxide gas into the interior space. The carbon monoxide gas is preferably delivered in a direction, represented by arrow  60 , parallel to the long axis of the slab  15  thereby forming a layer of carbon monoxide gas adjacent to the top surface  62  of the slab  15 , and preferably in contact with the top surface  62  of the slab  15 . A similar carbon monoxide header  64  with distribution pipes  66  and nozzles  68  is disposed below the slab  15  for distributing carbon monoxide gas in a direction, represented by arrow  70 , parallel to the long axis of the slab  15 , thereby forming a layer of carbon monoxide gas adjacent to the bottom surface  72  of the slab  15 , and preferably in contact with the bottom surface  72  of the slab.  
         [0094]    It is not required that all oxygen headers  30  reside amongst the carbon monoxide headers  28  as depicted in FIG. 6. For example, as shown in FIG. 1, it may be advantageous to construct several oxygen headers  30  in the heating furnace  10 . The carbon monoxide headers  28  would operate to discharge a sufficient amount of carbon monoxide to maintain the slab  15  enveloped in carbon monoxide gas about its upper surface  62  and lower surface  72 .  
         [0095]    The oxygen header  30  also comprises a pipe for conducting oxygen into the interior space  13  of the furnace  10 . The oxygen header  30  further comprises a plurality of distribution pipes  74  spaced apart in a generally horizontal configuration and descending into the interior space  13 . The distribution pipes  74  end in nozzles  76  for delivering oxygen into the interior space. The oxygen is preferably delivered in a direction, represented by arrow  78 , parallel to, or slightly inclined with respect to, the long axis of the slab  15 , thereby forming a layer of oxygen adjacent to the layer of carbon monoxide. A similar oxygen header  80  with distribution pipes  82  and nozzles  84  is disposed below the slab  15  and belt  34  for distributing oxygen in a direction, represented by arrow  86 , parallel to, or slightly inclined with respect to, the long axis of the slab  15 , thereby forming a layer of oxygen adjacent to the layer of carbon monoxide gas.  
         [0096]    The headers  28 ,  30 ,  64  and  80  are preferably rotatable, to thereby permit workers to selectively vary the injection angle, or inclination angle, formed by the nozzles  58 ,  68 ,  76  and  84  with respect to the steel slab  15 . For example, it may be desirable to point the nozzles toward the steel slab  15 , and this may be accomplished by turning some or all of the headers  28 ,  30 ,  64  and  80 , accordingly.  
         [0097]    As shown in FIG. 1, the carbon monoxide gas and oxygen delivered into the interior space of the furnace  10  travel in a direction, signified by arrows  88 , parallel to the direction of travel of the slab  15  through the furnace  10 , indicated by arrows  90 . The carbon monoxide and oxygen enter the interior furnace space where they are injected through their respective headers  28  and  30 , and are partially oxidized or combusted together in a combustion that is preferably initiated with a pilot light (not shown) as known to those of ordinary skill in the field. In operation, the combustion perpetuates itself because the carbon monoxide preferably has a temperature of 1100° F. when it is conveyed into the furnace  10  by the carbon monoxide headers  28 , which temperature is higher than the kindling point of the combustion that occurs between carbon monoxide and oxygen. Accordingly, the carbon monoxide spontaneously combusts as it comes in contact with oxygen.  
         [0098]    In the interior space, the carbon monoxide is oxidized according to the following reaction: 2 CO+O 2   - - - &gt;2  CO 2 +135,000 cal/mol. Any unoxidized carbon monoxide remains in the carbon monoxide layer next to the steel slab, thus shielding the steel slab from oxidation by superheated water vapor. The oxidation, or combustion, of the carbon monoxide in the interior space  13 , and hence the temperature, is controlled by controlling the volume of oxygen conveyed into the furnace  10  by the oxygen headers  28 . An amount of oxygen sufficient to combust part of the carbon monoxide is conveyed into the furnace  10  by the oxygen headers  30 , to maintain the furnace temperature as desired, leaving the excess carbon monoxide enveloping the steel slab  15  to inhibit, and preferably prevent, the slab  15  from oxidizing by contact with water vapor or other oxidizing substance. The temperature within the furnace  10  can be increased at various points by increasing the amount of oxygen conveyed into the furnace  10 .  
         [0099]    The flue gases, including carbon monoxide and CO 2 , travel parallel to the steel slab  15  and are removed from the furnace  10  through the hood  24  and flue  26 . Preferably, these hot gases are channeled through a heat exchanger for preheating carbon monoxide and oxygen prior to their injection into the furnace  10 . The preheated carbon monoxide and oxygen are injected into the interior furnace space, where the hot steel slab  15  provides sufficient heat to begin the oxidation reaction. This oxidation reaction burns carbon monoxide, yielding carbon dioxide and heat. The heat raises the temperature inside the furnace  10 , and is transferred to the steel slab by convection and radiant pressure from the housing  12  and heat-shield hearth  42 . This oxidation reaction is a nonluminous combustion reaction, which yields a higher temperature flue gas than is obtained with natural gas furnaces. Injection of additional carbon monoxide and oxygen into the furnace  10  perpetuates the oxidation reaction. Preferably, the temperature inside the furnace  10  may be varied in accordance with the temperature of the steel slabs  15  and the driving heat, in order to optimize the use of heat and more fully utilize the heat contained within the steel slabs  15 . For example, the temperature inside the furnace  10  could be raised to 1427° C. (2600° F.) to heat the steel slabs  15  to about 1204° C. (2200° F.), but if the steel slabs  15  contained sufficient heat, the temperature inside the furnace  10  would not need to be raised as high in order bring the slabs  15  to the desired temperature.  
         [0100]    The steel reheat furnace  10  is used in the steel making process as follows. Steel leaving the caster as large steel slabs at a temperature of about 815° C. (1500° F.) flows directly into the reheat furnace  10  of the present invention. This direct transfer of the steel slab  15  is preferably carried out without more than nominal cooling or oxidation of the steel slab  15  due to exposure to the atmosphere. Moreover, no special equipment is needed to handle the steel slab  15  since it preferably passes directly from the caster to the reheat furnace  10 . This permits the retention of sensible heat from the casting and utilizes this energy for metal rolling reduction.  
         [0101]    The steel slabs  15  enter the furnace  10  through the entrance opening  14  by displacing the curtain  36  and passing over the sealing drum  38  and then onto the support rollers  46  of the roller hearth  42 . The support rollers  46  are caused to turn by the friction of the continuous steel belt  32 . In turn, the friction of the turning support rollers  46  causes the steel slabs  15  to move toward the exit end of the furnace  10 . The support rollers  46  have minimal contact with the steel slab  15  due to a relatively small surface area being in contact with the steel slabs  15 , thus minimizing heat transfer from the steel slabs  15  to the support rollers  46  and eliminating formation of cold spots in the surface of the steel slabs  15 . As the steel slabs  15  transit the furnace  10 , it is enveloped in a carbon monoxide atmosphere formed by the layers of carbon monoxide gas adjacent to the steel slab  15  on both its top and bottom surfaces  62  and  72 , respectively. This carbon monoxide atmosphere eliminates the formation of superheated water vapor, and thus inhibits, and preferably eliminates, the formation of iron oxide scale on the surface of the steel slab  15 . At the same time, the carbon monoxide is oxidized as fuel for heating the furnace  10  to a preferred interior temperature of about 1427° C. (2600° F.) for heating the steel slab to about 1093° C. (2000° F.) throughout. Since steel is a relatively poor conductor of heat, transit time through the furnace  10  needs to be long enough for the entire steel slab  15  to reach a temperature of at least about 1093° C. (2000° F.). If surface and interior temperatures of the steel slab  15  are not somewhat uniform, the cross-sectional reduction of the slab  15  will not be uniform, and the gage of the rolled steel will vary, and the mechanical characteristics of the steel may vary during rolling, and the steel slab  15  may even tear. The heating of the steel slab  15  in the carbon monoxide atmosphere also reduces surface oxides produced during the slab casting process into metallics, thus achieving excellence in surface malleability and ductility and producing a butter smooth skin quality. Upon exiting the furnace  10 , the reheated steel slab  15  passes through the curtain at the exit opening and can then go directly to the rolling stands for reduction rolling.  
         [0102]    Referring now to FIG. 7, there is shown an illustrative embodiment of a steel heating furnace  100 , which includes features in addition to the those shown in conjunction with the furnace  10  of FIG. 1. It is to be understood that the internal workings of the furnace  10  of FIG. 1, as illustrated in FIGS.  2 - 6 , are included as part of the steel heating furnace  100  of FIG. 7. Accordingly, all structures, features and methods illustrated in FIGS.  2 - 6  and described above apply equally to the furnace  10  of FIG. 1 and the furnace  100  of FIG. 7, and references to one of more of FIGS.  2 - 6  will be made below in conjunction with FIG. 7 accordingly.  
         [0103]    The steel heating furnace  100  comprises an elongate furnace housing  102  defining an interior space  13  (see FIG. 2) into which a steel slab  15  (FIG. 2) to be reheated is received. The housing  102  has an entrance opening  14  through which the steel slab  15  enters the furnace, generally at a temperature of about 815° C. (1500° F.), and an exit opening  16  through which the reheated steel slab  15  exits the furnace  100  at a temperature of at least about 982° C. (1800° F.), and preferably at about 1093° C. (2000° F.). The housing  102  comprises a top  104  and sides  106 ,  108  that assist in sealing the interior space of the furnace  100  from the exterior atmosphere. Preferably, the top  104  and sides  106 ,  108  of the housing  102  are removable, such that waste materials from the interior of the furnace  100  can be removed easily, and also to facilitate maintenance of the furnace, when necessary. Preferably, the housing  102  is insulated to retain heat in the furnace  100 , thereby assisting in making the reheating process more efficient. As illustrated in FIG. 3, the insulation material  23  in the top  18  and sides  20 ,  22  of the housing of furnace  10  of FIG. 1, are also present in the furnace  100  of FIG. 7.  
         [0104]    In continued reference to FIG. 3, the at least one furnace hood  24  for collecting gases and channeling them out of the furnace  10  of FIG. 1 is also present in the furnace  100  of FIG. 7. A flue  26  is disposed on the hood  24  for conducting these gases out of the furnace. This hood system reduces and preferably eliminates leakage of furnace gases into the environment. Also disposed in the top  104  is at least one carbon monoxide header  28 , and preferably several as shown, for conducting carbon monoxide into the interior space, and at least one oxygen header  30  (preferably several as shown) for conducting oxygen into the interior space. These headers operate as described above.  
         [0105]    The furnace  100  of FIG. 7 is shown to include a system for regenerating carbon monoxide and engaging in destructive distillation of carbon sources, such as coal, to produce coke products. This system will now be described in conjunction with the embodiment of FIG. 7, in which the furnace gases preferably flow in opposing directions on either side of the flues  26  as shown by arrows  110 . Oxygen and carbon monoxide are delivered directionally as shown by arrows  78  and  60 , respectively, and by arrows  86  and  70 , respectively, in FIG. 6, by which the gas flow directions  110  are directed toward the flues  26  as shown of FIG. 7. The gas flow directions  110  are assisted in part by a venturi passage  116  which produces a lower pressure immediately downstream from itself to thereby draw gas flow toward and through itself. The flue gases, which comprise excess carbon monoxide as well as the carbon dioxide by-product formed by the combustion of the carbon monoxide with oxygen, have a high temperature when they are discharged from the flue  26 , preferably 2800° F.  
         [0106]    The flue gases pass from the flue  26 , and are divided to pass through flue gas conduits  112  and  119 . Part of the flue gases are conveyed through the conduit  112  into a rotary kiln  114  containing a carbon source, such as coke that contains a carbon residue, and the remainder of the flue gases are conveyed through conduit  115  by venturi passage  119  into a destructive distillation chamber  142  as described below in more detail.  
         [0107]    As those having ordinary skill will appreciate, the hot carbon dioxide portion of the flue gas is exposed to, and reacts with, the carbon reside of the coke in the kiln  114  to thereby regenerate a carbon monoxide by-product. The kiln  114  is preferably an inclined, rotational kiln, configured and arranged as known in the art to agitate and churn the coke  121  within the kiln  114  to thereby optimize the exposure and contact of the coke  121  with the hot carbon monoxide. As such, the unconsumed coke  121  that reaches the bottom of the rotary kiln  114  does not accumulate in an un-reacted state, but is rocked and churned such that it resides in exposure to the hot carbon dioxide. The rotary kiln  114  may be designed to include an internal conveyance means, or may be otherwise arranged, to cause the coke  121  that reaches the bottom of the kiln  114  to be conveyed back to the coke-entrance  123  thereof. The operation is preferably maintained such that an excess of carbon residue/coke resides in the rotary kiln  114  to thereby cause substantially all of the carbon dioxide portion of the flue gases to react with the carbon residue and become converted back into carbon monoxide as a useable by-product. It will be appreciated that the carbon monoxide has a much lower temperature when it is discharged into conduit  129  from the kiln  114 , preferably 1100° F., than the 2800° F. temperature of the hot flue gases upon their entry into the kiln  114  at gas entry  117 . This is due in part to the consumption of energy that is required to produce the reaction of the hot carbon dioxide with the carbon residue to produce carbon monoxide.  
         [0108]    The useable carbon monoxide by-product passes from the kiln  114  through conduit  125  and through a particle separator  118  and into a conduit  120  from which the gases are divided and routed in several different directions. Some of the carbon monoxide passes through a steam boiler  122  and into a gas storage chamber  124  for future use as a utility fuel. The remainder of the carbon monoxide is either re-circulated along conduit  126  and back into the kiln  114  by cooperative operation of a valve  128  and gas blower  130 , or is conveyed along conduit  132  and thereby re-routed back into the carbon monoxide headers  128  of the furnace  100 .  
         [0109]    The particle separator  118  operates to separate fly ash from the carbon monoxide passing through the conduit  125  from the kiln  114 . It will be appreciated that high temperatures would cause the fly ash to melt. The problem is addressed in part by lowering the relatively higher 2800° F. temperature of the hot flue gases entering at  117 , by combining those hot flue gases with the re-routed, lower-temperature (1100° F.) carbon monoxide that is conveyed into contact with the hot flue gases by the intersection of conduit  126  with conduit  112  at intersection point  133  which is the venturi passage  116 . The mixture of these gases at their different temperature results in the gases having a temperature of perhaps 1700-1800° F. This temperature of 1700-1800° F., while quite hot, is still lower than the 2800° F. temperature of the hot flue gases, and as the temperature is lowered still further to the 1100° F. described above as a result of the reaction within the kiln  114 , the fly ash is prevented from melting within the kiln  114  before it can be separated by particle separator  118 .  
         [0110]    It will also be appreciated that the volume of carbon monoxide gaseous fuel produced in the kiln  114  and discharged into conduit  125  is twice the volume of the carbon monoxide that is introduced into the furnace  100  at the carbon monoxide headers  28 . That is the reason why roughly half of the carbon monoxide discharged into conduit  120  must be diverted through the boiler  122  and preferably into the gas storage chamber  124 . This doubling in volume can be understood further by noting that the volume of gas flow into and out of the furnace housing  102  is relatively equivalent. The carbon monoxide that reacts with oxygen in the housing  102  to produce the useable carbon dioxide by-product gains double the oxygen as a result (2 CO+O 2   - - - &gt;2  CO 2 ), and the useable carbon dioxide by-product in turn becomes fully reacted with the carbon contained in the kiln  114  such that twice the volume is carbon monoxide is produced (2CO 2 +2C - - - &gt;4CO). Since all of the double-volume of oxygen, which intermediately forms a part of the carbon dioxide, is eventually converted to form carbon monoxide, the volume of regenerated carbon monoxide is naturally double the volume of carbon monoxide originally introduced into the carbon monoxide headers  28 . This can be represented stoichiometrically as follows, in which reaction (1) below occurs within the furnace housing  102 , and reaction (2) occurs within the rotary kiln  114 :  
                 (   oxidation   )                   2      CO     +         O   2        2          CO   2                       Total                 calories                 produced         +   135     ,              200                 calories                 per                 unit                 of                   O   2                   (   1   )                     (   reduction   )                   2        CO   2       +     2        C      4        CO                     Total                 calories                 recovered         -   81     ,              600                 calories                 per                 unit                 of                 original                   O   2                   from                 reaction                     (   1   )     .                  
          Total                 heat        /        energy                   produced   :                  Total                 calories                 not                 recoverable           +   53     ,              600                 calories                 per                 unit                 of                 original                   O     2                                from                 reaction                     (   1   )     .                                  (   2   )                               
 
         [0111]    It is seen from the above that reaction (1) is exothermic, while reaction (2) is endothermic, and further, that the product of reaction (2), 4CO, is double the volume of the original carbon monoxide 2CO from reaction (1). Reaction (2) assumes that there is a sufficient amount of sensible energy in the CO 2  and CO to cause the carbon (C) contained within the kiln  114  to react with all of the carbon dioxide (CO 2 ) produced in reaction (1), in which case it is noted that the amount of the useable carbon monoxide by-product of reaction (2) would be twice the amount of carbon monoxide supplied originally as part of reaction (1) above. Of course, if a lesser amount of either sensible energy, or carbon (C), is supplied to the kiln  114 , then the proportions represented above would be different, but it is preferred that an excess of carbon (C) reside in the kiln  114  to thereby cause all of the carbon dioxide (CO 2 ) to react within the kiln  114 , as energy levels should be sufficient under the normal working conditions of the furnace  100 .  
         [0112]    It should be noted that although the carbon monoxide atmosphere maintained within the furnace housing  102  probably eliminates the formation of iron oxide surface scale on the steel slab  15 , any iron oxide scale that does form from the reaction of the oxygen would react with the carbon monoxide atmosphere to product a small amount of carbon dioxide as well. Both the oxidation of the iron by oxygen, and the reduction of the iron oxide with the carbon monoxide to product carbon dioxide, product heat, thereby raising the temperature of the slab  15 , should any such oxidation occur. This carbon dioxide would mingle with the carbon dioxide formed by the combustion of carbon monoxide and oxygen within the furnace housing  102 , and pass through the flues  26 .  
         [0113]    The steel slab  15  is fed through the entrance opening  14  and onto the tops of the support rollers  46 . Side-support retaining rollers  46   a  are provided as outside support rollers on each shaft along either side of the movement path of the steel slabs  15 . As shown most clearly in FIG. 5A, the side-support retaining rollers  46   a  each include a proximal face  150  that preferably has the same diameter as the support rollers  46 . Also included is a frusto-conical retaining portion  152  which has a vertical thickness that is the same of the thickness of the drive belt  34 . It can be seen and understood from the drawings that the side-support retaining rollers  46   a , by being disposed in a substantial co-axial orientation with respect to the support rollers  46  in their respective rows, operate to prevent the steel slab  15  from deviating from a straight movement path through the furnace housing  102 . The frusto-conical retaining portion  152  extends upwardly, by the thickness of the belt  34 , higher than the bottom of the steel slab  15 , thus operating to nudge the steel slab  15  gently sidewise and forward into position if the steel slab deviates into contact with the portion  152 . The retaining rollers  46   a  are placed alongside the belt  34  and are supported in direct contact with stabilizer support rollers  48 , which are uniform in size as shown, and no portion of the belt  34  resides therebetween.  
         [0114]    It is to be understood that, alternatively, conventional combustion could be utilized within the majority of the furnace housing  102 , with the unique carbon monoxide atmosphere and combustion cycle reserved for perhaps the last section  102   a  of the furnace housing  102 . The portion of the furnace  110  using carbon monoxide as a fuel would in such cases depend on the availability of a sufficient quantity of carbon monoxide. In such an embodiment, an abundant amount of iron oxide surface scale would by formed on the steel slab  15  during the conventional combustion phase, but the scale would react with the hot carbon monoxide in the final section  102   a  to thereby form carbon dioxide from the scale as described above, effectively converting the metal oxide back to a metallic state that would have ductile qualities giving the surface of the steel a smooth finish. This alternative could be utilized if an excess of carbon monoxide by-product was not available.  
         [0115]    As shown in FIG. 7, the carbon source preferably originates from the coal contained in a coal bin  140 . The coal passes from the bin  140  into the destructive distillation chamber  142  as shown by arrow  144 . As those having ordinary skill in the relevant field will appreciate, coal contains volatiles. The high temperature carbon dioxide reacts with the advancing coal in the chamber  142  as part of the coking process, thereby converting the carbon dioxide to carbon monoxide. This carbon monoxide, along with the excessive amounts of un-combusted carbon monoxide that pass from the furnace  110  through the conduit  115 , carry significant amounts of sensible heat, sufficient to remove the volatiles from the coal. The carbon dioxide that enters from conduit  115  into the destructive distillation chamber  142 , reacts with the volatiles of the coal and drives them from the coal, to thereby produce coke as a by-product. It is possible that some carbon monoxide will be inadvertently produced in the destructive distillation chamber  142 , but it is preferred that this be minimized, if not eliminated, by limiting the amount of carbon dioxide conveyed into said destructive distillation chamber  142 .  
         [0116]    It follows from the above that the carbon dioxide conveyed from the flues  26  through conduit  119  preferably remains at about 2800° F., or some high temperature, as it enters the destructive distillation chamber  142 . The coal, when heated, also emits a heavy sulfur vapor, and the convection currents of the hot carbon dioxide and un-combusted carbon monoxide carry those sulfur vapors away from the coal and out of the chamber  142  through conduit  146  into a by-products area  148 , along with the other volatiles. The by-products area  148  represents any suitable processing system, as known to those of ordinary skill in the field, for receiving and processing the by-products of coke manufacture and similar procedures, such by-products including, but not limited to, sulfur, ammonium sulfate, hydrogen, and light hydrocarbons (both the benzene and methane series).  
         [0117]    Referring now to FIGS. 8 and 9, there is shown a preferred alternative embodiment, in which upper portions of the support rollers  46  reside within protective covers  154 . The covers  154  shield the upper portions of the support rollers  46  from the heat residing within the furnace housing  12  (FIGS. 1 and 5) or  102  (FIGS. 7 and 8- 9 ).  
         [0118]    The lower enclosed area  156  residing beneath the heat shield or hearth  42  is preferably maintained at a cooler temperature for several reasons that will be appreciated by those having ordinary skill in the field. This is accomplished by utilizing any suitable cooling means, such as water circulation means  158  for circulating cold water within the lower enclosed area  156 .  
         [0119]    It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present invention and the appended claims are intended to cover such modifications and arrangements. Thus, while the present invention has been shown in the drawings and fully described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred embodiment(s) of the invention, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, variations in size, materials, shape, form, function and manner of operation, assembly and use may be made without departing from the principles and concepts set forth herein.