Abstract:
A method for releasing an anhydrous gas in a gas phase at a target rate includes the step of obtaining a vessel at least partially filled with the anhydrous gas. The anhydrous gas is at least partially in a liquid phase and the vessel has an outlet for releasing the anhydrous gas in the gas phase. The method further includes releasing at least a portion of the anhydrous gas from the vessel through the outlet in the gas phase; applying a heat transfer fluid having a temperature of 32° F. to 150° F. to an exterior surface of the vessel during the releasing step, such that the anhydrous gas in the liquid phase is evaporated and the anhydrous gas in the gas phase is released at the target rate; and measuring starting and end weights of the vessel to monitor the releasing of the anhydrous gas in the gas phase.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Anhydrous gases, such as anhydrous halogen gases, are widely used in the chemical industry. For example, hydrogen bromide (HBr) is utilized in the production of inorganic bromides by reaction with metal hydroxides, oxides, or carbonates; in the production of organic bromides by reaction with alkyl alcohols or alkenes; as a catalyst for oxidations, alkylations, and condensations in organic chemistry, and for etching applications in the semiconductor manufacturing industry. 
         [0002]    HBr is typically supplied or shipped as a liquid, and more particularly a liquefied gas under its own vapor pressure (i.e., 297 psia or 2,048 kPa absolute) at 70° F. (21.1° C.), in a vessel. Liquefied gases are gases that transform to the liquid phase at normal temperatures inside a pressurized gas vessel. The liquid HBr is evaporated to a gas within the HBr vessel and the resulting anhydrous gaseous HBr is then fed to a reactor for use in various applications, such as those described above. Generally, it is desirable to have a rapid evaporation and flow of gaseous HBr from the cylinder to the reactor in order to minimize the overall process cycle time. 
         [0003]    There are various known systems to facilitate evaporation of a liquid gas within a vessel and supply of the gaseous gas from the vessel to a reactor. In one known system, ambient air is utilized to heat the exterior of the vessel containing the liquid HBr when the gaseous HBr is fed from the vessel to the reactor. The heat of the ambient air is transferred through the wall of the HBr vessel to the liquid HBr contained therein, thereby facilitating evaporation of the liquid HBr. The internal surface area of the vessel, the ambient air temperature, and the degree and efficiency of heat transfer between the ambient air and the vessel affect the evaporation rate of the HBr, thus the feed rate of the gaseous HBr from the vessel to the reactor. One drawback of such known systems is that, as some of the HBr evaporates into the gaseous state, the remaining liquid HBr cools, thereby resulting in a decreased rate of evaporation. As a result, the ambient air-heated HBr vessel cannot transfer the requisite amount of gaseous HBr to the reactor in a timely manner. More particularly, while the feed or transfer rate of such vessels is initially approximately 100 kg/hr or greater, the rate generally drops off to almost 0 kg/hr as the vessel&#39;s contents cool. Another drawback of ambient air-heated vessels is that liquid HBr is often left within the vessels and returned to the HBr vendor, which increases the overall raw material costs for a given campaign. 
         [0004]    Another known system for evaporating liquid HBr involves passing the liquid HBr from the vessel through a heat exchanger, which has a greater surface area than that of the vessel, and using ambient air as a heating source. In turn, the evaporation rate of the HBr is increased. However, a drawback of such known systems is that they require additional transfer piping, which can become easily fouled by dissolved solids entrained within the liquid HBr. Accordingly, for this type of known system, it is necessary to utilize filters and/or periodically clean the transfer piping, which increases the overall process cycle time. Additionally, transfer of the liquid HBr to the heat exchanger requires additional controls and careful attention, thereby increasing the complexity and costs associated with the system, as compared with systems in which the HBr is evaporated within the vessel. Such known systems also suffer the drawback of increased raw material costs due to liquid HBr being left within the vessels. 
         [0005]    Another known system involves direct heating of the vessel itself, such as by steam, electric blankets or heated solutions. Such a conventional vessel has a relief device built therein in order to prevent catastrophic over-pressurization of the vessel. Such conventional systems typically exhibit increased heat transfer and sufficient energy to meet the cycle time evaporation and feed flow rates. However, if the HBr vessel is overheated, the HBr vessel may generate increased pressure which causes the relief device to fail. Also, the direct heat may damage the relief device, resulting in a release of corrosive HBr gas from the vessel. Such damage to the relief device may occur during the actual feed period due to the evaporative effect of the HBr or even after the feed period, when the overall vessel temperature increases thereby making the vessel more susceptible to premature future failure. Accordingly, HBr vessel manufacturers typically do not recommend or permit customers to heat their vessels. 
         [0006]    Accordingly, it would be desirable to provide an evaporator and feed system which allows for rapid and controlled formation and feeding of anhydrous gases. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a method for releasing an anhydrous gas in a gas phase at a target rate. The method comprises the step of obtaining a vessel at least partially filled with the anhydrous gas, the anhydrous gas being at least partially in a liquid phase and the vessel having an outlet for releasing the anhydrous gas in the gas phase. The method further comprises the steps of releasing at least a portion of the anhydrous gas from the vessel through the outlet in the gas phase; applying a heat transfer fluid having a temperature in the range of 32 to 150° F. to an exterior surface of the vessel during the releasing step, such that the anhydrous gas in the liquid phase is evaporated and the anhydrous gas in the gas phase is released at the target rate; and measuring a starting weight of the vessel and an end weight of the vessel to monitor the releasing of the anhydrous gas in the gas phase. 
         [0008]    Another aspect of the present invention is directed to evaporator and feed system for releasing an anhydrous gas in a gas phase at a target rate. The system comprises a vessel at least partially filled with the anhydrous gas. The anhydrous gas is at least partially in a liquid phase and the vessel has an outlet for releasing the anhydrous gas in the gas phase. The system further comprises a scale assembly including a weight sensor. The vessel is positioned on and supported by a surface of the scale assembly, such that the scale assembly measures a weight of the vessel. The system further comprises a heating assembly for applying a heat transfer fluid having a temperature in the range of 32 to 150° F. to an exterior surface of the vessel during the releasing step, such that the anhydrous gas in the liquid phase is evaporated and the anhydrous gas in the gas phase is released at the target rate. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0009]    The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. These drawings are included for the purpose of illustrating a preferred embodiment of the invention. The invention is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
           [0010]      FIG. 1  is a schematic diagram of a preferred embodiment of a process for evaporating liquid HBr and feeding HBr vapor to a reactor; 
           [0011]      FIG. 2  is a top perspective view of a cylinder positioned atop a scale assembly in accordance with a preferred embodiment of the present invention; and 
           [0012]      FIG. 3  is a side elevational view of a evaporator and feed system in accordance with a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “lower”, and “upper” designate directions in the drawings to which reference is made. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the evaporator and feed system and designated parts thereof. The terminology includes the above-listed words, derivatives thereof, and words of similar import. Additionally, the words “a” and “an”, as used in the claims and in the corresponding portions of the specification, mean “at least one.” 
         [0014]    Referring to the drawings in detail, wherein like numerals and characters indicate like elements throughout, there is shown in  FIGS. 1-3  a presently preferred embodiment of an evaporator and feed system in accordance with the present invention. 
         [0015]    Referring particularly to  FIG. 1 , there is shown an evaporator and feed system, generally designated  10 , for hydrogen bromide (HBr). It will be understood by those skilled in the art, that while the system and method of the present invention are described herein in the context of HBr, the system and method are equally applicable to any anhydrous gas, and particularly to any halogen gases (such as hydrogen chloride, hydrogen fluoride, hydrogen iodide and the like), a CO 2 , a H 2 , a O 2 , a N 2 , a HS and the like. 
         [0016]    The system  10  includes a first vessel  12  and a second vessel  14 . The first vessel  12  is preferably an evaporator vessel or evaporator, and the second vessel  14  is preferably a reaction vessel or reactor located downstream of the evaporator  12 . Referring to  FIG. 2 , more preferably, the evaporator  12  is in the form of a generally tubular and closed pressure cylinder  12  including a first, generally closed end  12   a , a second, generally closed end  12   b , and a generally tubular sidewall  22  extending therebetween. The cylinder  12  may be vertically-oriented or horizontally-oriented, but is preferably horizontally-oriented as shown. More preferably, the cylinder  12  is horizontally-oriented along a first longitudinal axis X 1  (see  FIG. 3 ). The cylinder  12  is preferably made of a metal, such as carbon steel or nickel. The cylinder  12  may also be made of a metal plated with carbon steel or nickel. More preferably, the cylinder  12  is made of A-515 or A-516 Grade 70 carbon steel. It will be understood by those skilled in the art that the evaporator  12  need not be in the form of a cylinder, and may take the form of any conventionally known vessel. 
         [0017]    The cylinder  12  is preferably a pressurized vessel which is initially at least partially filled with HBr in the liquid phase (i.e., liquefied HBr gas under pressure). Preferably, the liquefied HBr is stored within the cylinder  12  under a vapor pressure of 220 to 317 psia and at a temperature of approximately 45° F. to 77° F. More preferably, the liquefied HBr is stored within the cylinder  12  under a vapor pressure of 290 to 317 psia and at a temperature of 68° F. to 77° F. Most preferably, the liquefied HBr gas is stored within the cylinder  12  under its own vapor pressure of about 297 psig (2,048 kPa absolute) at a temperature of approximately 70° F. (21.1° C.). 
         [0018]    Referring to  FIGS. 2-3 , in the present embodiment, the cylinder  12  preferably has a length L of 5 to 10 feet, and more preferably approximately 7 feet, measured from the first end  12   a  to the second end  12   b . The cylinder  12  preferably has a diameter D of 1 to 4 feet, and more preferably approximately 2.5 feet. The cylinder  12  preferably has an internal volume of 25 to 35 cubic feet, and more preferably approximately 27 cubic feet. However, it will be understood by those skilled in the art that the dimensions of the cylinder  12  may vary as necessary to suit the process applications of the end user. 
         [0019]    The cylinder  12  is preferably at least partially filled with liquid phase HBr from a raw material source (not shown). The liquid HBr preferably initially occupies approximately 80% to 90%, and more preferably approximately 90%, of the internal volume of the cylinder  12 . Preferably, the cylinder  12  is also cleaned prior to filling with liquid HBr. 
         [0020]    At least a portion, and preferably substantially all, of the liquid phase HBr stored within the cylinder  12  evaporates to form gaseous HBr. The cylinder  12  preferably includes an outlet  26  for removing or permitting an outflow or release of gaseous HBr from the cylinder  12 . Preferably, the outlet  26  is in fluid communication with an outlet conduit  24  equipped with a metered nozzle (not shown), a control valve  42  which can be selectively opened and closed, and/or one or more pressure and/or flow indicators (not shown), for measured and controlled feed of the gaseous HBr from the cylinder  12  (via the outlet  26 ) to the reactor  14 . Accordingly, feed of the gaseous HBr to the reactor  14  commences after evaporation when the nozzle and/or valve  42  of the outlet conduit  24  is opened. 
         [0021]    The system  10  further includes a heating assembly  16  for facilitating evaporation of the liquid HBr (see  FIGS. 1 and 3 ). In one embodiment, the heating assembly  16  is preferably a tubular hose or delivery pipe  18  disposed at least slightly above the cylinder  12  and containing a fluid at initial temperatures sufficient to at least gently heat the cylinder  12 . The fluid is applied to the cylinder  12  as gaseous HBr is released therefrom. More particularly, the heat transfer fluid delivery by the delivery pipe  18  raises the temperature of the exterior and then the interior of the cylinder  12 . More preferably, the pipe  18  is horizontally-oriented above and aligned with a geometric center of the cylinder  12 , such that the delivery pipe  18  extends along a second longitudinal axis X 2  which is spaced apart from and generally parallel to the first longitudinal axis X 1  of the cylinder  12 . The delivery pipe  18  preferably delivers the heat transfer fluid contained therein to impinge upon the outer surface of the cylinder  12  for heating thereof. 
         [0022]    The delivery pipe  18  is preferably disposed up to 36 inches (i.e., 3 feet) above the cylinder  12 , and more preferably approximately 10 inches above the cylinder  12 . It will be understood that the delivery pipe  18  may be spaced apart from the cylinder  12  by more than 36 inches, depending on the wind currents, as long as the output stream of the heat transfer fluid is not misdirected. The delivery pipe  18  is preferably made of stainless steel, carbon steel, poly carbon steel or painted carbon steel. Most preferably, the delivery pipe  18  is made of 304 stainless steel. It will be understood, however, that the delivery pipe  18  may be made of any material that is thermally compatible with the heat transfer fluid. Preferably, the delivery pipe  18  has an outer diameter of approximately ⅛ to 2 inches, and more preferably approximately ¼ to 1 inch. Most preferably, the delivery pipe  18  has an outer diameter of approximately ½ inches. Preferably, the length of the delivery pipe  18  is substantially equal to the length L of the cylinder  12  (i.e., approximately 7 feet). However, it will be understood that the length L of the delivery pipe  18  may be shorter or longer than the length L of the cylinder  12 , as long as the delivery pipe  18  extends over at least a portion of the length L of the cylinder  12 . 
         [0023]    Referring to  FIG. 1 , in one embodiment, the delivery pipe  18  is supplied by a water source  44 , and more preferably by an industrial water source  44 , such that the heat transfer fluid for the cylinder  12  is water. The heat transfer fluid, preferably water, flowing through the delivery pipe  18  is maintained at an initial temperature of approximately 32° F. to 150° F., preferably up to approximately 77° F., more preferably approximately 45° F. to 77° F., and most preferably approximately 68° F. to 77° F. In one embodiment, the temperature of the heat transfer fluid is preferably approximately 70° F. It will be understood by those skilled in the art that upper limit of the temperature of the heat transfer fluid is not limited to the specific values recited herein. Instead, the upper limit of the heat transfer fluid temperature is limited only by the pressure rating of the safety relief device on the cylinder for the particular liquefied gas contained therein. 
         [0024]    It will also be understood by those skilled in the art that the heated water need not be industrial water (though this is preferred for cost saving purposes), but rather may be supplied from any available water source. It will also be understood by those skilled in the art that another fluid with a thermal conductivity similar to water may be supplied to the delivery pipe  18  instead of water. Such alternative fluids preferably have thermal conductivities comparable to that of water. Examples of such alternative fluids includes propylene glycol, ethylene glycol, betaine, polyalkylene glycol, mineral oils, a silicone-based fluid (such as SYLTHERM™), any mixture thereof, or any mixture of one or more of these fluids with water. 
         [0025]    Referring to  FIG. 3 , the delivery pipe  18  is preferably provided with at least one downwardly facing aperture  20 , and more preferably with a plurality of spaced-apart and downwardly facing apertures  20  formed along at least a portion of the lower surface of the delivery pipe  18 . More preferably, a plurality of spaced-apart and downwardly facing apertures  20  are formed along the entire length of the lower surface of the delivery pipe  18  that covers the cylinder  12 . Each aperture  20  preferably has a diameter of approximately 1/32 to ⅛ inches, and preferably approximately 1/32 to ½ inches, and most preferably approximately 1/16 inches. Each aperture  20  is preferably spaced apart from an adjacent aperture by a span of approximately ½ to 4 inches, and more preferably approximately 1 to 3 inches, and most preferably approximately 2 inches. The delivery pipe  18  preferably includes approximately 32 apertures  20 . It will be understood that the size, spacing and number of apertures  20  may vary depending on the specification of the particular application of use. At one or more locations between the water source  44  and the first aperture  20 , the delivery pipe  18  may be equipped with one or more valves  46 , such as ball valves, for controlling the flow of water to the cylinder  12 . 
         [0026]    The apertures  20  are preferably formed at least in a portion of the delivery pipe  18  facing the cylinder  12 . Accordingly, when water flow through the delivery pipe  18  is initiated, the water passes through the apertures  20  and onto an exterior periphery  22   a  of the sidewall  22  of the cylinder  12 . Preferably, the water flows through the delivery pipe  18  at a rate of approximately 5 to 10 gallons per minute, and more preferably approximately 8 gallons per minute. The flow of water through each aperture  20  is preferably approximately 0.1 to 0.4 gallons per minute, and more preferably approximately 0.2 gallons per minute. It will be understood that the flow rate of the heat transfer fluid (i.e., the water) through and out of the delivery pipe  18  may vary depending on the ambient temperature and the flow rate of the HBr. 
         [0027]    More particularly, the water initially contacts the horizontally-oriented cylinder  12  at an upper portion  12   c  thereof which is proximate the delivery pipe  18 . Upon contact with the cylinder  12 , the water naturally flows (by gravity) from the upper portion  12   c  around the cylinder  12 , and more preferably around both sides of the cylinder  12 , toward an opposing lower portion  12   d , which is distal from the delivery pipe  18  and proximate a ground surface  48 , while following the arcuate contour of the exterior periphery  22  of the cylinder  12 . 
         [0028]    As such, the delivered heat transfer fluid directly contacts and heats a large portion of the surface area of the exterior periphery  22   a  of the sidewall  22  of the cylinder  12 . More preferably, the delivered heat transfer fluid directly contacts substantially all of the surface area of the exterior periphery  22   a  of the sidewall  22  of the cylinder  12 . Accordingly, over time, the delivered heat transfer fluid maintains the internal temperature of the cylinder  12  at approximately 45° F. to 77° F., and more preferably 68° F. to 77° F., and most preferably approximately 70° F. More particularly, the delivered heat transfer fluid maintains the liquid HBr which is remaining in the cylinder  12  and which has yet to be evaporated at a temperature of approximately 45° F. to 77° F., and more preferably 68° F. to 77° F., and most preferably approximately 70° F., thereby counteracting any cooling effect that naturally occurs within cylinder  12  as the evaporated gaseous HBr begins to be flowed to the reactor  14  from the cylinder  12 . In turn, the evaporation rate of the liquid HBr remaining in the cylinder  12  is better controlled and uniformly maintained, such that the feed rate of gaseous HBr from the cylinder  12  to the reactor  14  is better controlled and uniformly maintained. 
         [0029]    More particularly, the heating assembly  16  provides sufficient heating of the cylinder  12 , even when ambient air temperatures approach 32° F., to effect evaporation of the liquid HBr contained therein, such that virtually (and preferably absolutely) no liquid HBr remains in the cylinder  12  after the vapor feeding process is completed. The heating assembly  16  also facilitates release of the gaseous HBr from the cylinder  12  to the reactor  14  at a target rate. Further, because the heating assembly  16  utilizes a heat transfer fluid at relatively low temperatures, there is no danger of overheating of the cylinder  12 . 
         [0030]    Referring to  FIGS. 2-3 , the system  10  further includes a scale assembly  28 . The scale assembly  28  includes a base pad  30  including a weight sensor  50 , a display (not shown) electrically connected to the weight sensor  50 , a support plate  32  positioned on the base pad  30 , and at least two spaced-apart cylinder supports  34  positioned on top of the support plate  32 . The support plate  32  is preferably in the form of a tray or pan, such that the support plate  32  includes upwardly extending edges  36 . The support plate  32  preferably has a sufficiently large length and width so as to encompass the cylinder  12 . The support plate  32  may be made of carbon steel, stainless steel or any material that would structurally be capable of supporting the weight of the filled HBr cylinder  12 . Preferably, the support plate  32  is made of carbon steel, and more preferably primed ¼ inch thick carbon steel. Each of the cylinder supports  34  preferably has a sufficient length so as to extend along at least a portion of the length L of the cylinder  12 , and more preferably along at least 50% of the length L of the cylinder  12 . The cylinder supports  34  may be made of carbon steel, stainless steel or any material that would structurally be capable of supporting the weight of the filled HBr cylinder  12 . Preferably, the cylinder supports  34  are made of carbon steel, and more preferably 3 inch thick carbon steel. 
         [0031]    For assembly of the scale assembly  28 , the base pad  30  is positioned on a floor or ground surface  48 , or other supporting surface, and the support plate  32  is secured to a top surface of the base pad  30 . Preferably, the support plate  32  is attached to the base pad  30  by a single fastener (not shown), such as a bolt. However, it will be understood that multiple fasteners may be utilized and/or alternative conventionally known securing mechanisms may be utilized to attach the support plate  32  to the base pad  30 . Next, the cylinder supports  34  are positioned on a top surface of the support plate  32 , at least slightly interior of the edges  36 . The cylinder supports  34  may simply rest on the support plate  32  or they may be attached thereto using any conventionally known securing mechanism. 
         [0032]    In use, a cylinder  12  containing liquid HBr is placed directly or indirectly (i.e., one or more additional supports may be situated between the cylinder  12  and the cylinder supports  34 ) on top of the cylinder supports  34  of the assembled scale assembly  28 . Then, the cylinder  12  is attached to a feed manifold for the reactor  14 . As shown in  FIG. 1 , in one embodiment, multiple cylinders  12  are connected to the reactor  14  for feeding of HBr vapor thereto. Within the cylinder  12 , the liquid HBr begins to evaporate to form gaseous HBr. Next, the nozzle and/or valve of the outlet conduit  24  extending from the outlet  26  of the cylinder  12  is opened so as to commence feeding of gaseous HBr to the reactor  14 . Substantially simultaneously, or soon thereafter, fluid (i.e., water) flow through the delivery pipe  18  of the heating assembly  16  is initiated, such that heated water is delivered to the external periphery  22   a  of the cylinder  12 , in order to heat and maintain the temperature of the cylinder  12  at approximately 70° F., maintain a target rapid evaporation rate of the liquid HBr and maintain a target rapid feed rate of the gaseous HBr from the cylinder  12  to the reactor  14 . 
         [0033]    Preferably, liquid HBr evaporates to form gaseous HBr at a rate of 75 to 200 kg/hr, and more preferably 100 to 175 kg/hr, and most preferably approximately 125 to 150 kg/hr. There is no accumulation of gaseous HBr in the cylinder  12 . Thus, the gaseous HBr is delivered or fed to a reactor  14  at the same rate as the liquid HBr evaporates. That is, the gaseous HBr is preferably fed to the reactor  14  at a rate of 75 to 200 kg/hr, and more preferably 100 to 175 kg/hr, and most preferably approximately 125 to 150 kg/hr. However, it will be understood by those skilled in the art that the evaporation and delivery/feed rates may vary based on the end application, the initial volume of liquid HBr in the cylinder  12 , the size of the cylinder  12 , the overall volume of the cylinder  12 , and the like. 
         [0034]    The heat transfer fluid (i.e., water) travels from the upper portion  22   a  of the cylinder  12  to the bottom portion  22   b  proximate the cylinder supports  34 . The upwardly extending edges  36  of the supporting plate  32  contains the delivered water and directs it toward a drain  38 , preferably via one or more rigid and/or flexible pipes or hoses  40  (see  FIG. 1 ). The drained and collected water may then be disposed of or may be recycled and returned to the water source  44  for repeated application to the cylinder  12 . 
         [0035]    The heat transfer fluid is delivered to the cylinder  12  and the outlet  26  remains open until all of the gaseous HBr has been transferred out of the cylinder  12  and into the reactor  14 . To completely empty the cylinder  12 , this process typically takes approximately 7 to 9 hours and more preferably approximately 7.5 hours. However, it will be understood that the overall process time is dependent upon the initial volume of liquid HBr in the cylinder  12 , the overall volume of the cylinder  12 , the evaporation rate and the feed rate. Also, the overall process time is dependent upon whether a cylinder  12  is being fully or only partially emptied. 
         [0036]    Preferably, completion of the process, and more particularly, completion of the feeding of the gaseous HBr can be determined by reference to the scale assembly  28 . Specifically, assuming that the starting empty weight of the cylinder  12  is known or predetermined, an operator can reference the display of the scale assembly  28 , which will initially indicate a starting weight of the cylinder  12 , when the cylinder  12  is filled with liquid HBr. The scale assembly  28  will then indicate a gradually decreasing weight, as the liquid HBr is evaporated to form gaseous HBr and the gaseous HBr is transferred out of the cylinder  12 . The operator can confirm that all or substantially all of the gaseous HBr has been transferred out of the cylinder  12  when the scale assembly  28  indicates an end weight that is generally equal to the predetermined starting empty weight of the empty cylinder  12 . Preferably, the process is completed when the end weight is within ±5% of the predetermined starting empty weight of the cylinder  12 . Also, the temperature and/or the application or flow rate of the heat transfer fluid may be adjusted based on measurements from the scale assembly  28 . 
         [0037]    It will be appreciated by those skilled in the art that changes could be made to the embodiment described above without departing from the broad inventive concepts thereof. Also, based on this disclosure, a person of ordinary skill in the art would further recognize that the relative proportions of the components illustrated could be varied without departing from the spirit and scope of the invention. It is understood, therefore, that this invention is not limited to the particular embodiment disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.