US3329344A - Multiple zone heating system - Google Patents
Multiple zone heating system Download PDFInfo
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- US3329344A US3329344A US574398A US57439866A US3329344A US 3329344 A US3329344 A US 3329344A US 574398 A US574398 A US 574398A US 57439866 A US57439866 A US 57439866A US 3329344 A US3329344 A US 3329344A
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- 238000010438 heat treatment Methods 0.000 title claims description 61
- 239000007788 liquid Substances 0.000 claims description 134
- 238000012546 transfer Methods 0.000 claims description 47
- 239000012530 fluid Substances 0.000 claims description 27
- 238000009434 installation Methods 0.000 claims description 15
- 230000001105 regulatory effect Effects 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 6
- 238000004891 communication Methods 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000003039 volatile agent Substances 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 4
- 239000000374 eutectic mixture Substances 0.000 description 4
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 4
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 4
- 238000012856 packing Methods 0.000 description 3
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- 230000000694 effects Effects 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 235000010333 potassium nitrate Nutrition 0.000 description 2
- 239000004323 potassium nitrate Substances 0.000 description 2
- 239000011833 salt mixture Substances 0.000 description 2
- 235000010344 sodium nitrate Nutrition 0.000 description 2
- 239000004317 sodium nitrate Substances 0.000 description 2
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-LZFNBGRKSA-N Potassium-45 Chemical compound [45K] ZLMJMSJWJFRBEC-LZFNBGRKSA-N 0.000 description 1
- 206010037660 Pyrexia Diseases 0.000 description 1
- 241000219492 Quercus Species 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000009172 bursting Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
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- 238000001035 drying Methods 0.000 description 1
- 210000004907 gland Anatomy 0.000 description 1
- 239000013529 heat transfer fluid Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 238000000034 method Methods 0.000 description 1
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- PDEDQSAFHNADLV-UHFFFAOYSA-M potassium;disodium;dinitrate;nitrite Chemical compound [Na+].[Na+].[K+].[O-]N=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PDEDQSAFHNADLV-UHFFFAOYSA-M 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 235000010288 sodium nitrite Nutrition 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D1/00—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
- F28D1/02—Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
- F28D1/0206—Heat exchangers immersed in a large body of liquid
- F28D1/0213—Heat exchangers immersed in a large body of liquid for heating or cooling a liquid in a tank
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D7/00—Central heating systems employing heat-transfer fluids not covered by groups F24D1/00 - F24D5/00, e.g. oil, salt or gas
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
- F28F27/02—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus for controlling the distribution of heat-exchange media between different channels
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D2220/00—Components of central heating installations excluding heat sources
- F24D2220/08—Storage tanks
Definitions
- the hea-ting systems disclosed herein are specifically intended to employ eutectic mixtures of inorganic salts in molten form as heat transfer liquids. These mixtures make extremely desirable heat transfer liquids since they can @be heated to temperatures in the range of 100G-1050" F. without deterioration. The importance of high temperatures becomes apparent when it is recognized that a radiator heated to l050 F. will emit four times as much radiant energy per square foot of emitting surface per hour as one heated to 600 F., which is the maximum practical tempera-ture attainable by other heat transfer liquids. Moreover, molten eutectic salt mixtures are noncorrosive and nontoxic and are circulated in liquid form so that they exert no vapor pressure on the system in which they are incorporated. Accordingly, they may be used withou-t taking elaborate precautions against corrosion, t-oxication, or bursting of system components.
- control valves to direct and regulate the flow of the heat transfer medium.
- control valves suitable for this purpose have internal components such as packings and seals for which there are no known materials capable of withstanding the 1000 F. or higher ltemperatures attainable by molten eutectic salt mixtures. Accordingly, conventional control techniques cannot be used in systems employing such media.
- a central heating unit is employed to maintain a reservoir of the molten eutectic mixture at a given temperature level.
- the liquid for each of the heat using centers or zones is drawn from a separate compartment or chamber in the reservoir into which liquid can flow from the main body of liquid in the reservoir.
- the temperature of the liquid withdrawn from the compartmentalized chamber for each zone is independently regulated by returning to and mixing withV the relatively hot liquid flowing into the chamber from the main body of liquid a selectively variable proportion of the relatively cooler liquid discharged from the associated zone or load center of the heat using end of the system.
- the temperature of the liquid delivered to the zone supplied from each compartmentalized chamber can be lowered or raised to meet the temperature requirements of the zone. Diversion of varying proportions of the liquid discharged from each zone or load center into the associated compartmentalized chamber in the reservoir can be readily accomplished by any of several simple packingand seal-free mechanical flow proportioning arrangements regulated by controllers which have sensors in and therefore respond to the temperature in the load centers or zones.
- one important primary object of the present invention is the provision of multizone heating systems employing high temperature circulating heat transfer media and provided with controls for independently regulating the temperature of the liquid supplied-to each of the heat using zones.
- Ithe control arrangement for regulating the temperature of the heat transfer medium supplied to each of the heat using zones or load centers includes an arrangement for mixing a selectively variable proportion of the relatively cool liquid returned from the zone or load center with liquid drawn from a reservoir of relatively hot liquid maintained at a generally uniform temperature;
- control arrangement for regulating the temperature of the heat transfer medium is free of packings, seals, and other components which are not capable of withstanding high temperature;
- FIGURE l shows the relationship of FIGURES lA and 1B which, together, constitute a generally diagrammatic illustration of a multiple zone or ⁇ load heating installation constructed in accord with the principles of the present invention
- FIGURE 2 is a section through a heat exchange unit incorporated in a multiple zone heat user in the heating installation of FIGURE l;
- FIGURE 3 is a section through the heat exchange unit to a reduced scale, taken substantially along line 3 3 of FIGURE 2;
- FIGURE 4 is a partial, partly sectioned plan view of heat transfer fluid heating and storage units incorporated in the heating installation of FIGURE ⁇ l;
- FIGURE 5 is a partly sectioned diagrammatic side view of a second, exemplary form of ow divider which may be used in hea-ting installations constructed in accord with the principles of the present invention
- FIGURE 6 is a partly sectioned, diagrammatic front View of the flow divider of FIG. 5:
- FIGURE 7 is a view similar to FIGURE 5 of a third, exemplary form of flow divider which may be used in heating installations constructed in accord with the principles of the present invention.
- FIGURES is a partly sectioned, diagrammatic front view of the flow divider of FIGURE 7.
- FIGURES lA and 1B depict a multiple zone heating installation 20 constructed in accord with the principles of the present invention and including my novel arrangement for independently regulating the temperature of a circulating heat transfer liquid supplied to each of the several zones of a multiple zone heat using unit 22 in the installation.
- the illustrated heat using unit 22 is a multiple pass vertical dryer.
- This dryer which is exemplary of the multiple zone heat using units with which the present invention may be advantageously employed, includes a plurality of rotatably supported rolls 24 arranged in upper and lower rows 26 and 28.
- the rolls in upper row 26 are directly above the spaces y.between the rolls in lower row 28 to direct a web 30 of product to be treated through the, dryer in a plurality of parallel, spaced apart passes or zones 32A-D extending between the two rows of rolls.
- fluid supply-return and radiantv heating units 34 and 36 oriented adjacent and parallel to passes 32.
- each of the fluid supply-return and radiant heating units 34 incorporated in dryer 22 includes elongated main supply and return ducts 38 and 40 separated by a common dividing wall 41.
- Branch supply and return ducts 42 and 44 extend transversely across the main supply and return ducts, the arrangement of these components on both sides of the main duct pairs being identical.
- the main and branch ducts are integral, the common walls 46 of the main ducts forming the bottom walls for the branch ducts. Pairs of branch supply ducts are alternated with pairs of branch return ducts, and the branch ducts are arranged with their side Walls in abutting relationship.
- Branch supply ducts 42 communicate with main supply ducts 38 through apertures 48 (see FIGURE 2) in the com-mon wall 46 between the main and branch ducts adjacent the wall 41 separating the main supply and return ducts.
- Branch return ducts 44 similarly communicate with main return duct 40 ⁇ through apertures 50 in common Wall 46 0n the side of common partition 41 opposite apertures 48.
- Air or other treating fluid is accelerated and directed normally at high velocity (typically on the order of 2,000- 15,000 feet per minute) against web 30 by nozzles 52 xed to the exterior wall 54 of each branch supply duct 42.
- the nozzle inlets communicate with the interior of the duct through apertures 56 in exterior branch duct wall 54.
- the treating fluid exiting from nozzles 52 contacts the surfaces of web 30 ⁇ at high velocity, scouring away from the surfaces volatiles evolved from the web.
- the spent fluid together with its burden of evolved volatiles, flows into branch return ducts 44 through inlet apertures 58 formed in exterior wall 54.
- Units 34 also include radiant heaters 62 as shown in FIGURES 1B, 2, and 3.
- Each heater has a plurality of parallel, spaced apart, straight tubular legs 64 having coplanar centerlines and extending in the same direction as branch ducts 42 and 44.
- the legs 64 are connected by tubular end bends 66 alternately located at opposite ends of the heater.
- the rows of nozzles 52 and exhaust apertures 56 are disposed between adjacent legs 64 of the radiant heater.
- Units 36 which are located outside the outermost passes 32A and D, may be identical to units 34 except that there are branch supply and return ducts and their associated supply nozzles and exhaust openings only on one side of the main ducts of these units.
- the treating iluid is supplied to the main supply duct 38 in each unit 34 and 36 by a blower 68 connected l through a duct 70 to a uid heater 72 incorporated in a fluid heating system (not otherwise shown), which may be of the type disclosed in application No. 537,132, if desired. From fluid heater 72, the treating fluid flows through a syste-m supply duct 74 into the main supply ducts 38 of units 34 and 36.
- the spent treating uid and its burden of evolved volatiles flows from branch return ducts 44 of units 34 and 36 into the associated unit main return ducts 40. From these ducts, the spent Huid and its burden flows into system return duct 76.
- Main system return duct 7 6 is preferably connected to the inlet of blower 68 so that the spent treating fluid ma" be recirculated through the system. This eliminates the loss of sensible heat which would result if the spent uid were discharged from the system.
- main system return duct 76 is provided with a make-up duct 7S; and a vent duct 80 is located in the duct 70 between blower 68 and fluid heater 72.
- Valves 82 and 84 control the flow through make-up and vent ducts 78 and 80, respectively. Valves 82 and 84 may be adjusted manually or, if desired, may be automatically controlled as disclosed in my U.S. Patent No. 3,208,158 issued Sept. 28, 1965, for Dryers.
- Radiant heaters ⁇ 62 are heated to operating temperature by circulating through them a heated, liquid heat transfer medium such as HTS.
- HTS is a eutectic mixture of inorganic salts having a melting point of approximately 288 F.
- HTS is formulated of 40% sodium nitrite, 7% sodium nitrate, and 53% potassium nitrate. HTS of this compoistion is marketed by Du Pont as Hitec, by American Cyanamid as Aeroheat 300, and by American Hydrotherm as Hydrotherm 1200. Variations of the above composition include the commercially available HTS mixture of 55% potassium nitrate and 45% sodium nitrate. The physical characteristics of HTS are discussed in detail in an article by I-I. P. Voznick et al. entitled Molten Salt for Heat Transfer in the May 27, 1963, issue of Chemical IEngineering to which reference may be had if desired.
- HTS as a circulating heat transfer liquid4
- it may be circulated at extremely high temper-atures (up to 1050 F.) in liquid form. Consequently, the radiant heaters may be heated to heretofore unobtainable temperatures; and yet the system components need be designed to withstand only very low pressures because liquid HTS has negligible Vapor pressure.
- HTS is stable, does not foul, and has superior thermal properties. In contrast to the heat transfer metals, it is safe, nontoxic7 and has both low corrosion rates and low inventory costs. Moreover, HTS has an excellent thermal carrying capacity and is relatively inexpensive.
- one of the most important features of the present linvention is the no-vel system provided for heating the liquid medium, circulating it through the radiators 62 in the several zones ⁇ or passes 32 of dryer 22, and independently controlling the temperature of the radiators 62 in each of the dryer zones.
- This system includes as major components a liquid heating unit 86, a storage tank 88 for the heated liquid, a zone circulation and control system 90 for each of the dryer zones 32, and an auxiliary system including a heating unit 92 for melting the HTS when the installation is started up.
- Liquid heating unit 86 which may be of any desired construction, is connected to storage tank SS by supply and return conduits 94 and 96.
- a pump 98 in storage tank 88 and connected to the inlet of return conduit 96 circulates heat transfer liquid from the storage tank through the heating unit and back to the storage tank.
- Suitable conventional controls are provided to so regulate the operation of heating unit 86 that it will maintain the heated liquid in the storage tank at a constant, preselected temperature.
- Storage tank 88 therefore constitutes a reservoir from which heat transfer liquid at the selected temperature may be withdrawn and circulated through dryer zones 32A-D to maintain the radiators 62 in the latter at operating temperature.
- each of the zone circulating and control systems includes an individual compartment or chamber 100 within the main storage tank 88.
- Each compartment 100 communicates with the main body of liquid 102 in the storage tank through a weir 104. Therefore, if the liquid level in a compartment 100 falls below the level of liquid body 102, liquid will flow into the compartment through its weir 104, tending to restore the liquid level in the compartment to the level of liquid body 102.
- Insulation 105 surrounding each compartment or tank 100 thermally isolates the liquid in the compartment from the main body of liquid 102. This permits the liquid in the compartments to be maintained at temper-atures different from that of the liquid in main body 102.
- heat transfer liquid is circulated from compartment 100 of the associated circulation and control system 90 to the radiators 62 in dryer zone 32a through a main zone supply conduit 106 and branch zone supply conduits 108 by a zone pump 110 in the compartment.
- the liquid now at a lower temperature, flows through branch return conduits 112 and main zone return conduit 114 to a flow proportioning control 116.
- Control 116 regulates the temperature of the heat transfer liquid supplied from compartment 100 to zone 32A.
- flow proportioning control 116 includes a trough or bucket 118 pivotally mounted 'on rods or pins 120 above compartment side wall 122. Rectangular openings 124 and 125 in bucket 118 discharge the liquid returned from radiators 62 in zone 32A to bucket 118 into compartment 100 'and into the main body of liquid 102 in storage tank 88, respectively.
- Bucket 118 is connected through a link 126 to the piston 127 of a pneumatic or hydraulic motor 128 (see FIGURE 1A).
- the operation of motor 128 is regulated by a temperature responsive controller 130 having a sensor 132 in contact with one of the radiators 62 in zone 32A.
- controller 130 will pivot bucket 118 to the position shown for the bucket in the controller of zone 32B. With bucket 118 thus positioned, all of the liquid returned from dryer 22 will be discharged into the main body of liquid 102 in storage tank 88. Since liquid is being continuously Withdrawn from compartment 100 by zone pump 110, this will cause a drop in the liquid level in compartment 100. Accordingly, relatively hot liquid will flow into compartment 100 through opening 104. This increases the temperature of the liquid in compartment 100 and, accordingly, the temperature of the liquid supplied to the radiators 62 in zone 32A, raising the temperature of the latter. In actual practice the compartments 100 would contain baflling or other appropriate structure to effect an intimate mixing of the liquid flowing into the compartment and thereby maintain all of the liquid in the compartment at a uniform temperature.
- temperature controller' 130 acting through motor 128, shifts bucket 118 toward the illustrated position. With the bucket moving toward this position, an increasing proportion of the liquid discharged from dryer 22 is diverted into compartment 100 and a decreasing proportion into the main body of liquid 102. This decreases the temperature of the liquid in compartment due to the reduced proportion of hot liquid flowing into the compartment from main body 102. Thus, the rate of increase of the temperature of radiators 62 is reduced as they approach the desired temperature.
- bucket 118 With a constant heat load in zone 32A and the radiators 62 in this zone at the desired temperature, bucket 118 will be positioned so that the proportions of the liquid owing into the tank from bucket 118 and from the main body of liquid 102 will maintain the temperature in the zone at the desired level.
- proportioning control 116 is simi-lar if the temperature of the radiators 62 in zone 32A rises above the desired level because of a decreasing heat load in zone 32A or other reason.
- temperature controller 130 acting through motor 128, shifts bucket 118 toward the position of the bucket of the controller for zone 32C. This increases the volume of relatively cool liquid discharged into compartment 100 and decreases the volume of hotter liquid flowing into compartment 100 through Weir 104 from the main body of liquid'102 in storage tank 88. This lowers the temperature of the liquid in compartment 100 available for supply to zone 32A, reducing the temperature of the liquid supplied to the zone in response to the decreasing heat load to maintain the radiator 62 in the zone at the desired temperature.
- Controllers 116 are not limited to this mode of control, however. For example, it may be desirable to regulate the temperature of the radiators by the speed of the web 30 moving through dryer 22, the temperature of the radiators being increased as the web speed increases. Temperature controllers may be readily programmed to effect this mode of operation; or the same result may be accomplished by making controllers 130 responsive to the speed of the web rather than radiator temperature. In short, with only minor modifications which will be obvious to those skilled in the control arts, flow proportioning control 116 may be made to respond to any one of several parameters or to various combinations of such parameters.
- the buckets When heating installation 20 is shut down, the buckets may be emptied by shifting them to the position of the bucket in the controller for zone 32C. This eliminates the need for an auxiliary heating system to melt HTS in the buckets when the system is started up.
- flow proportioning control 133 includes a transition member 136 fixed to the discharge end of zone return conduit 114, a flow dividing member 138, and a hydraulic or pneumatic motor 140.
- Transition lmember 136 which may be of any desired configuration, has an elongated slit 142 through which the liuid returning through main zone return conduit 114 is discharged.
- the fluid flowing through slit 142 is divided into two streams by flow dividing member 138, one of the streams flowing into compartment 100 and the other into the main body of liquid 102 in storage tank 88.
- the temperature of the liquid in the latter may be regulated in substantially the same manner as in the embodiment of the invention de scribed previously.
- the proportion of the kliuid diverted into compartment 100 is altered by repositioning flow divider 138. This is accomplished by fixing flow dividing member 138 to a pivot rod 144 journalled in bearings 146 at the upper edge of zone compartment side wall 122. Pivot rod 144 is connected through link 148 to the piston rod 150 of motor 149 which, when operated, moves the ow divider.
- the operation of motor 140 is regulated by a controller such as that described above in conjunction with the embodiment of FIGURE 1.
- a weir box 152 is mounted below the discharge end of return conduit 114 and above zone compartment side wall 122. Liquid flowing into weir box 152 from return conduit 114 is discharged from the box through a weir 154 in its side wall 156.
- a flow dividing vane 158 which may be identical to the vane 138 described above, is positioned in the path of the liquid liowing through weir 154. Vane 158 divides this flow into two streams, one of which is discharged into zone compartment 100 and the other of which is discharged into the main body of liquid 102 in storage tank 88.
- liow dividing vane 158 is connected through pivot pin 160 and link 162 to a vane-positioning motor in the same manner as in the embodiment of FIGURE 5.
- the modus operandi of this embodiment and the embodiment of FIGURES and 6 are substantially identical.
- the exemplary embodiment of the present invention illustrated in FIGURE 1 alsor includes an auxiliary heating system including a heating unit 92 for melting the solid heat transfer medium when the system is started up. Since HTS must be heated to a temperature of 288 F. to melt it, steam is preferably employed as a circulating heat transfer medium in this system. From heating unit 92, the steam flows through supply conduit 164 into heating coils 166 disposed in the i storage tank 88 for the circulating medium. From the heating coils the steam or other heat transfer lluid is returned to heating unit 92 through a main return conduit 168. Heating coils 166 melt the main body of heat transfer medium 102 in tank 88.
- heating coils 170 are connected in parallel between supply and return conduits 164 and 16S.
- supply and return conduits 172 and 174 are also connected in parallel between main supply and return conduits 164 and 168, which connect auxiliary heating unit 91 with dryer 22.
- conduits 172 and 174 supply the heat transfer medium to and return it from tubular fluid circulating members 176 fixed to the legs 64 of the radiant heaters 62 in heat exchange units 34 and 36.
- the conduits and fluid circulating members are connected through supply and return headers 178 and 180 and branch conduits 182, only part of which are shown.
- a multiple Zone heating installation comprising:
- means including a fluid heater and a first circulating system comprising a uid circulator and supply and return conduits connecting said fluid heater to said storage means for maintaining the body of heat transfer medium .in said storage means substantially at a given temperature level;
- compartment means in said storage means for each of said zones the interior of each said compartment means being in iiuid communication with the main body of liquid in said storage means, whereby said liquid can ow into said compartment means as liquid in said compartment means is withdrawn therefrom;
- a circulation system comprising supply and return conduits and a circulator for supplying liquid from each said compartment means to the associated zone of the heat using means and for returning the liquid thus supplied to said storage means;
- each said compartment means may constitute a mixture of relatively cool liquid returned from the associated zone and relatively hot liquid from the main body of liquid in the storage means of different proportions and the temperature of the liquid in each said compartment means and available for supply to the associated zone may therefore be independently regulated.
- (b) including an auxiliary system for liquefying the heat transfer medium comprising heat exchangers adapted to have a heated duid circulated therethrough so disposed in the storage means as to heat the main body of heat transfer medium therein and in each of said compartment means so as to heat the medium in the compartment, means for heating said uid, and Imeans including supply and return conduits connecting said fluid heating means to said heat exchangers.
- each of said compartment means is thermally insulated from the main body of heat transfer medium in the storage means therefor.
- a multiple zone heating system comprising:
- heating means for maintaining the main body of heat t-ransfer medium in said storage means substanitally at a given temperature level
- (1g) means operably associated with the compartment in the storage means for the zone for supplying relatively cool liquid -returned from the zone and relatively hot liquid from the main body of liquid in the storage means to said compartment to maintain a body of liquid therein;
- (h) means for controlling the proportion of cool to hot liquid thus supplied to said compartment and thereby governing the temperature of the liquid in said compartment and available for supply to said zone.
- thermoregulating means associated with each of said zones comprises means on the supply side of said circulation system for mixing rela-tively hot liquid from the liquid heating means with relatively cool liquid returned from the zone to thereby govern the temperature of the liquid available for supply to the zone.
- said proportion controlling means comprises temperature sensing means in the zone and fluid -directing means operatively connected thereto ⁇ and capable of diverting varying proportions of the returning fluid into said compartment to thereby regulate the proportion of returning fluid delivered to said compartment and therefore the proportion of cool to hot liquid as the temperature detected by said sensing means changes, whereby the temperature of the liquid in the compartment and available for supply to the zone may be increased and decreased as the sensed temperature changes -to compensate for'changing heat demands in said zone.
- a multiple zone heating installation comprising:
- compartment means for each of said zones the interior of each said compartment means being in uid communication with the main body of liquid in said storage means; whereby said liquid can flow into said compartment means as liquid in said compartment means is withdrawn therefrom;
- each said compartment means may constitute a mixture of relatively cool liquid returned from the associated zone and relatively hot liquid from the main body of liquid in the storage means of different proportions and the temperature of the liquid in each said compartment means and available for supply to the associated zone may therefore be independently regulated.
Description
July 4, 1967 H. L.; SMITH, Jr 3,329,344
MULTIPLE ZONE HEATING SYSTEM Filed Aug. 25, 1966 4 Sheets-Sheet l FIG IB F/G. M l
-gal' INVENTOR. ,sfo/m01? L. sfu/TH, 4R.
ATTORNEY July 4, 1967 H, 1 sMlTHl JR 3,329,344,A
MULTIPLE ZONE HEATING SYSTEM 4 Sheets-Sheet Filed Aug. 23, 1966 IG. 7B
INVENTOR. HORACE L. sfu/TH, JR. BY
July 4, 1967 H.1 SMITH, .1R
MULTIPLE ZNE HEATING SYSTEM 4 Sheets-Sheet 5 Filed Aug.
amm mZON umm mzON mmm mZON JNVENTOR.
' HORACE L. sM/m, ./f?.
July 4, 1967 sMrrH, JR 3,329,344
MULTIPLE ZONE HEATING SYSTEM 4 Sheets-Sheet 4- Filed Aug. 23, 1966 JN V EN TOR.. HORACE L. SMITH, Jl?.
United States Patent O 3,329,344 MULTIPLE ZONE HEATING SYSTEM Horace L. Smith, Jr., Richmond, Va., assignor to Hupp Corporation, Cleveland, Ohio, a corporation of Virginia Filed Aug. 23, 1%6, Ser. No. 574,398 Claims. (Cl. 237-8) This invention relates to heating systems and, more particularly, to novel, improved heating systems of the circulating liquid type.
The hea-ting systems disclosed herein are specifically intended to employ eutectic mixtures of inorganic salts in molten form as heat transfer liquids. These mixtures make extremely desirable heat transfer liquids since they can @be heated to temperatures in the range of 100G-1050" F. without deterioration. The importance of high temperatures becomes apparent when it is recognized that a radiator heated to l050 F. will emit four times as much radiant energy per square foot of emitting surface per hour as one heated to 600 F., which is the maximum practical tempera-ture attainable by other heat transfer liquids. Moreover, molten eutectic salt mixtures are noncorrosive and nontoxic and are circulated in liquid form so that they exert no vapor pressure on the system in which they are incorporated. Accordingly, they may be used withou-t taking elaborate precautions against corrosion, t-oxication, or bursting of system components.
Components for heating, handling and circulating these media have been developed; and systems employing t-hem are in use in a few specific specialized areas. They are not, however, in general use. This is because most heating systems in which they could be advantageously employed must be capable of supplying the heat transfer medium to several load centers or zones at different temperatures so that various temperature requirements may be met in the different centers or zones. Moreover, this must be accomplished with a central or common fluid heating unit as the provision of a separate fluid heater for each zone or lload center is not economically feasible.
In systems employing more conventional heat transfer media such as hot water and steam zonal temperature control is readily accomplished by employing suitable control valves to direct and regulate the flow of the heat transfer medium. However, control valves suitable for this purpose have internal components such as packings and seals for which there are no known materials capable of withstanding the 1000 F. or higher ltemperatures attainable by molten eutectic salt mixtures. Accordingly, conventional control techniques cannot be used in systems employing such media.
However, I have now invented a novel arrangement for independently controlling the temperature of a molten eutectic mixture delivered to each of the several zones of a multizone heating system which does not employ conventional control valves to regulate and direct the flow of the circulating heat transfer liquid and which fulfills the requirement that all of the liquid for the system be heated by a common heating unit.
In my novel system, a central heating unit is employed to maintain a reservoir of the molten eutectic mixture at a given temperature level. The liquid for each of the heat using centers or zones is drawn from a separate compartment or chamber in the reservoir into which liquid can flow from the main body of liquid in the reservoir. The temperature of the liquid withdrawn from the compartmentalized chamber for each zone is independently regulated by returning to and mixing withV the relatively hot liquid flowing into the chamber from the main body of liquid a selectively variable proportion of the relatively cooler liquid discharged from the associated zone or load center of the heat using end of the system.
By respectively increasing and decreasing the propor- "ice tion of cooler returning liquid to hot liquid from the main body in the reservoir, the temperature of the liquid delivered to the zone supplied from each compartmentalized chamber can be lowered or raised to meet the temperature requirements of the zone. Diversion of varying proportions of the liquid discharged from each zone or load center into the associated compartmentalized chamber in the reservoir can be readily accomplished by any of several simple packingand seal-free mechanical flow proportioning arrangements regulated by controllers which have sensors in and therefore respond to the temperature in the load centers or zones.
From the foregoing, it will =be apparent that one important primary object of the present invention is the provision of multizone heating systems employing high temperature circulating heat transfer media and provided with controls for independently regulating the temperature of the liquid supplied-to each of the heat using zones.
Other important, but more specific objects of the present invention include the provision of heating systems as described in the preceding object:
(l) Which employ heat transfer -media that are solids at normal ambient temperatures and which include an auxiliary heating system for melting the solid media when the system is started up;
(2) In which Ithe control arrangement for regulating the temperature of the heat transfer medium supplied to each of the heat using zones or load centers includes an arrangement for mixing a selectively variable proportion of the relatively cool liquid returned from the zone or load center with liquid drawn from a reservoir of relatively hot liquid maintained at a generally uniform temperature;
(3) In which the control arrangement for regulating the temperature of the heat transfer medium is free of packings, seals, and other components which are not capable of withstanding high temperature;
(4) In w-hich the aforesaid control arrangement is simple, reliable, and inexpensive to manufacture and service.
Additional objects, further novel features, and other advantages of the present invention will be apparent from the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing, in which:
FIGURE l shows the relationship of FIGURES lA and 1B which, together, constitute a generally diagrammatic illustration of a multiple zone or `load heating installation constructed in accord with the principles of the present invention;
FIGURE 2 is a section through a heat exchange unit incorporated in a multiple zone heat user in the heating installation of FIGURE l;
FIGURE 3 is a section through the heat exchange unit to a reduced scale, taken substantially along line 3 3 of FIGURE 2;
FIGURE 4 is a partial, partly sectioned plan view of heat transfer fluid heating and storage units incorporated in the heating installation of FIGURE `l;
FIGURE 5 is a partly sectioned diagrammatic side view of a second, exemplary form of ow divider which may be used in hea-ting installations constructed in accord with the principles of the present invention;
FIGURE 6 is a partly sectioned, diagrammatic front View of the flow divider of FIG. 5:
FIGURE 7 is a view similar to FIGURE 5 of a third, exemplary form of flow divider which may be used in heating installations constructed in accord with the principles of the present invention; and
FIGURES is a partly sectioned, diagrammatic front view of the flow divider of FIGURE 7.
Referring now to the drawing, FIGURES lA and 1B depict a multiple zone heating installation 20 constructed in accord with the principles of the present invention and including my novel arrangement for independently regulating the temperature of a circulating heat transfer liquid supplied to each of the several zones of a multiple zone heat using unit 22 in the installation.
The illustrated heat using unit 22 is a multiple pass vertical dryer. This dryer, which is exemplary of the multiple zone heat using units with which the present invention may be advantageously employed, includes a plurality of rotatably supported rolls 24 arranged in upper and lower rows 26 and 28. The rolls in upper row 26 are directly above the spaces y.between the rolls in lower row 28 to direct a web 30 of product to be treated through the, dryer in a plurality of parallel, spaced apart passes or zones 32A-D extending between the two rows of rolls. As the web of product 30l moves through dryer 22, it is dried and evolved volatiles are carried away from it by fluid supply-return and radiantv heating units 34 and 36 oriented adjacent and parallel to passes 32.
Referring now to FIGURES 1B, 2, and 3, each of the fluid supply-return and radiant heating units 34 incorporated in dryer 22 includes elongated main supply and return ducts 38 and 40 separated by a common dividing wall 41. Branch supply and return ducts 42 and 44 extend transversely across the main supply and return ducts, the arrangement of these components on both sides of the main duct pairs being identical. As shown in FIGURE 2, the main and branch ducts are integral, the common walls 46 of the main ducts forming the bottom walls for the branch ducts. Pairs of branch supply ducts are alternated with pairs of branch return ducts, and the branch ducts are arranged with their side Walls in abutting relationship.
Air or other treating fluid is accelerated and directed normally at high velocity (typically on the order of 2,000- 15,000 feet per minute) against web 30 by nozzles 52 xed to the exterior wall 54 of each branch supply duct 42. The nozzle inlets communicate with the interior of the duct through apertures 56 in exterior branch duct wall 54. The treating fluid exiting from nozzles 52 contacts the surfaces of web 30` at high velocity, scouring away from the surfaces volatiles evolved from the web. The spent fluid, together with its burden of evolved volatiles, flows into branch return ducts 44 through inlet apertures 58 formed in exterior wall 54.
Units of the type discussed above are described in more detail in my copending application No. 537,132, filed Mar. 24, 1966, for Apparatus and System (which has been abandoned) to which reference may be had if deemed necessary for a more complete understanding of the present invention.
The treating iluid is supplied to the main supply duct 38 in each unit 34 and 36 by a blower 68 connected l through a duct 70 to a uid heater 72 incorporated in a fluid heating system (not otherwise shown), which may be of the type disclosed in application No. 537,132, if desired. From fluid heater 72, the treating fluid flows through a syste-m supply duct 74 into the main supply ducts 38 of units 34 and 36.
The spent treating uid and its burden of evolved volatiles flows from branch return ducts 44 of units 34 and 36 into the associated unit main return ducts 40. From these ducts, the spent Huid and its burden flows into system return duct 76.
Main system return duct 7 6 is preferably connected to the inlet of blower 68 so that the spent treating fluid ma" be recirculated through the system. This eliminates the loss of sensible heat which would result if the spent uid were discharged from the system.
In many applications of the present invention, such as in the drying of paper, the percentage of moisture or other volatiles in the treating duid must be closely controlled to produce the desired characteristics in the treated product. To permit such control, main system return duct 76 is provided with a make-up duct 7S; and a vent duct 80 is located in the duct 70 between blower 68 and fluid heater 72. Valves 82 and 84 control the flow through make-up and vent ducts 78 and 80, respectively. Valves 82 and 84 may be adjusted manually or, if desired, may be automatically controlled as disclosed in my U.S. Patent No. 3,208,158 issued Sept. 28, 1965, for Dryers.
Radiant heaters `62 are heated to operating temperature by circulating through them a heated, liquid heat transfer medium such as HTS. HTS is a eutectic mixture of inorganic salts having a melting point of approximately 288 F.
Most commonly, HTS is formulated of 40% sodium nitrite, 7% sodium nitrate, and 53% potassium nitrate. HTS of this compoistion is marketed by Du Pont as Hitec, by American Cyanamid as Aeroheat 300, and by American Hydrotherm as Hydrotherm 1200. Variations of the above composition include the commercially available HTS mixture of 55% potassium nitrate and 45% sodium nitrate. The physical characteristics of HTS are discussed in detail in an article by I-I. P. Voznick et al. entitled Molten Salt for Heat Transfer in the May 27, 1963, issue of Chemical IEngineering to which reference may be had if desired.
The primary advantage of using HTS as a circulating heat transfer liquid4 is that it may be circulated at extremely high temper-atures (up to 1050 F.) in liquid form. Consequently, the radiant heaters may be heated to heretofore unobtainable temperatures; and yet the system components need be designed to withstand only very low pressures because liquid HTS has negligible Vapor pressure.
Also, unlike high boiling point hydrocarbons and other organic heat transfer mediums, HTS is stable, does not foul, and has superior thermal properties. In contrast to the heat transfer metals, it is safe, nontoxic7 and has both low corrosion rates and low inventory costs. Moreover, HTS has an excellent thermal carrying capacity and is relatively inexpensive.
Referring now primarily to FIGURES 1A and 4, one of the most important features of the present linvention is the no-vel system provided for heating the liquid medium, circulating it through the radiators 62 in the several zones `or passes 32 of dryer 22, and independently controlling the temperature of the radiators 62 in each of the dryer zones. This system includes as major components a liquid heating unit 86, a storage tank 88 for the heated liquid, a zone circulation and control system 90 for each of the dryer zones 32, and an auxiliary system including a heating unit 92 for melting the HTS when the installation is started up.
Referring still to FIGURE 1A, each of the zone circulating and control systems provided for this purpose includes an individual compartment or chamber 100 within the main storage tank 88. Each compartment 100 communicates with the main body of liquid 102 in the storage tank through a weir 104. Therefore, if the liquid level in a compartment 100 falls below the level of liquid body 102, liquid will flow into the compartment through its weir 104, tending to restore the liquid level in the compartment to the level of liquid body 102.
Referring now to both FIGURES lA and 1B, heat transfer liquid is circulated from compartment 100 of the associated circulation and control system 90 to the radiators 62 in dryer zone 32a through a main zone supply conduit 106 and branch zone supply conduits 108 by a zone pump 110 in the compartment. After circulating through the radiators, the liquid, now at a lower temperature, flows through branch return conduits 112 and main zone return conduit 114 to a flow proportioning control 116. Control 116 regulates the temperature of the heat transfer liquid supplied from compartment 100 to zone 32A.
As shown in FIGURES 1A and 4, flow proportioning control 116 includes a trough or bucket 118 pivotally mounted 'on rods or pins 120 above compartment side wall 122. Rectangular openings 124 and 125 in bucket 118 discharge the liquid returned from radiators 62 in zone 32A to bucket 118 into compartment 100 'and into the main body of liquid 102 in storage tank 88, respectively.
Assuming first that the radia-tor temperature in zone 32A drops below that which it is desired to maintain, controller 130 will pivot bucket 118 to the position shown for the bucket in the controller of zone 32B. With bucket 118 thus positioned, all of the liquid returned from dryer 22 will be discharged into the main body of liquid 102 in storage tank 88. Since liquid is being continuously Withdrawn from compartment 100 by zone pump 110, this will cause a drop in the liquid level in compartment 100. Accordingly, relatively hot liquid will flow into compartment 100 through opening 104. This increases the temperature of the liquid in compartment 100 and, accordingly, the temperature of the liquid supplied to the radiators 62 in zone 32A, raising the temperature of the latter. In actual practice the compartments 100 Would contain baflling or other appropriate structure to effect an intimate mixing of the liquid flowing into the compartment and thereby maintain all of the liquid in the compartment at a uniform temperature.
As the temperature of the radiators in zone 32A approaches the desired temperature, temperature controller' 130, acting through motor 128, shifts bucket 118 toward the illustrated position. With the bucket moving toward this position, an increasing proportion of the liquid discharged from dryer 22 is diverted into compartment 100 and a decreasing proportion into the main body of liquid 102. This decreases the temperature of the liquid in compartment due to the reduced proportion of hot liquid flowing into the compartment from main body 102. Thus, the rate of increase of the temperature of radiators 62 is reduced as they approach the desired temperature.
With a constant heat load in zone 32A and the radiators 62 in this zone at the desired temperature, bucket 118 will be positioned so that the proportions of the liquid owing into the tank from bucket 118 and from the main body of liquid 102 will maintain the temperature in the zone at the desired level.
The function of proportioning control 116 is simi-lar if the temperature of the radiators 62 in zone 32A rises above the desired level because of a decreasing heat load in zone 32A or other reason. In this event, temperature controller 130, acting through motor 128, shifts bucket 118 toward the position of the bucket of the controller for zone 32C. This increases the volume of relatively cool liquid discharged into compartment 100 and decreases the volume of hotter liquid flowing into compartment 100 through Weir 104 from the main body of liquid'102 in storage tank 88. This lowers the temperature of the liquid in compartment 100 available for supply to zone 32A, reducing the temperature of the liquid supplied to the zone in response to the decreasing heat load to maintain the radiator 62 in the zone at the desired temperature.
The foregoing description of the operation of flow proportioning controllers 116 assumed that the temperature of the radiators in the zones was to be maintained constant. Controllers 116 are not limited to this mode of control, however. For example, it may be desirable to regulate the temperature of the radiators by the speed of the web 30 moving through dryer 22, the temperature of the radiators being increased as the web speed increases. Temperature controllers may be readily programmed to effect this mode of operation; or the same result may be accomplished by making controllers 130 responsive to the speed of the web rather than radiator temperature. In short, with only minor modifications which will be obvious to those skilled in the control arts, flow proportioning control 116 may be made to respond to any one of several parameters or to various combinations of such parameters.
When heating installation 20 is shut down, the buckets may be emptied by shifting them to the position of the bucket in the controller for zone 32C. This eliminates the need for an auxiliary heating system to melt HTS in the buckets when the system is started up.
The novel control arrangement just described, which is duplicated for zones 32B-D, is an important feature of the present invention since, heretofore, there was no Way of providing independent zone control in systems employing HTS or similar fluids as heat transfer media. As indicated above, this is because valves and other conventional control components have packing glands, seals, and similar temperature sensitive components which are not capable of withstanding the temperatures to which such heat transfer media may be heated.
It will be apparent to those skilled in the arts'to which the present invention pertains that many structural modifications may be made in the exemplary embodiment of the present invention described above, if desired. For example, rectangular weir 104 may be relocated to the bottom of compartment 100 or replaced by weirs or openings of other configurations. Similarly, openings of shapes other than rectangular may be provided in bucket 118 of flow proportioning control 116 depending upon the type of control desired.
Further, the flow proportioning control shown in FIG- URES lA and 1B may be replaced with flow proportioning controls 133 (FIGURES 5 and 6) or 134 (FIGURES 7 and 8), if desired. Referring rst to FIGURES 5 and 6, flow proportioning control 133 includes a transition member 136 fixed to the discharge end of zone return conduit 114, a flow dividing member 138, and a hydraulic or pneumatic motor 140. Transition lmember 136, which may be of any desired configuration, has an elongated slit 142 through which the liuid returning through main zone return conduit 114 is discharged. The fluid flowing through slit 142 is divided into two streams by flow dividing member 138, one of the streams flowing into compartment 100 and the other into the main body of liquid 102 in storage tank 88. By varying the ow volume of the fluid stream diverted into compartment 100, the temperature of the liquid in the latter may be regulated in substantially the same manner as in the embodiment of the invention de scribed previously.
The proportion of the kliuid diverted into compartment 100 is altered by repositioning flow divider 138. This is accomplished by fixing flow dividing member 138 to a pivot rod 144 journalled in bearings 146 at the upper edge of zone compartment side wall 122. Pivot rod 144 is connected through link 148 to the piston rod 150 of motor 149 which, when operated, moves the ow divider. The operation of motor 140 is regulated by a controller such as that described above in conjunction with the embodiment of FIGURE 1.
In the llow proportioning control 134 illustrated in FIGURES 7 and 8, a weir box 152 is mounted below the discharge end of return conduit 114 and above zone compartment side wall 122. Liquid flowing into weir box 152 from return conduit 114 is discharged from the box through a weir 154 in its side wall 156. A flow dividing vane 158, which may be identical to the vane 138 described above, is positioned in the path of the liquid liowing through weir 154. Vane 158 divides this flow into two streams, one of which is discharged into zone compartment 100 and the other of which is discharged into the main body of liquid 102 in storage tank 88. In this ernbodiment of the invention, liow dividing vane 158 is connected through pivot pin 160 and link 162 to a vane-positioning motor in the same manner as in the embodiment of FIGURE 5. The modus operandi of this embodiment and the embodiment of FIGURES and 6 are substantially identical.
As indicated above, the exemplary embodiment of the present invention illustrated in FIGURE 1 alsor includes an auxiliary heating system including a heating unit 92 for melting the solid heat transfer medium when the system is started up. Since HTS must be heated to a temperature of 288 F. to melt it, steam is preferably employed as a circulating heat transfer medium in this system. From heating unit 92, the steam flows through supply conduit 164 into heating coils 166 disposed in the i storage tank 88 for the circulating medium. From the heating coils the steam or other heat transfer lluid is returned to heating unit 92 through a main return conduit 168. Heating coils 166 melt the main body of heat transfer medium 102 in tank 88.
To melt the heat transfer medium in the zone compartments 100, heating coils 170 are connected in parallel between supply and return conduits 164 and 16S.
Also connected in parallel between main supply and return conduits 164 and 168 are supply and return conduits 172 and 174, which connect auxiliary heating unit 91 with dryer 22. As shown in FIGURES 1B, 2, and 3, conduits 172 and 174 supply the heat transfer medium to and return it from tubular fluid circulating members 176 fixed to the legs 64 of the radiant heaters 62 in heat exchange units 34 and 36. The conduits and fluid circulating members are connected through supply and return headers 178 and 180 and branch conduits 182, only part of which are shown.
When the installation is shut down, all of the HTS drains back into the main tank from the radiators which leaves them free of salt. Upon start-up the steam owing through tubes 176 preheats the radiators to a ternperature above the melting point of the salt so that when the salt is pumped into them it will not congeal.
When the system is shut down a cold liquid can be run through the auxiliary system described above to quickly reduce the temperature of the heat transfer liquid in the various components.
The invention may be embodied in other specic forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
What is claimed and desired to be secured by Letters Patent is:
1. A multiple Zone heating installation, comprising:
(a) storage means containing a body of heat transfer medium adapted to be circulated in liquid form;
(b) means including a fluid heater and a first circulating system comprising a uid circulator and supply and return conduits connecting said fluid heater to said storage means for maintaining the body of heat transfer medium .in said storage means substantially at a given temperature level;
(c) multizone heat using means;
(d) compartment means in said storage means for each of said zones, the interior of each said compartment means being in iiuid communication with the main body of liquid in said storage means, whereby said liquid can ow into said compartment means as liquid in said compartment means is withdrawn therefrom;
(e) a circulation system comprising supply and return conduits and a circulator for supplying liquid from each said compartment means to the associated zone of the heat using means and for returning the liquid thus supplied to said storage means; and
(f) independently adjustable, flow dividing means for dividing the liquid returned fro-m each said zone between the compartment means from which the liquid was supplied and the main body of liquid in the storage means;
(g) whereby the liquid supplied to each said compartment means may constitute a mixture of relatively cool liquid returned from the associated zone and relatively hot liquid from the main body of liquid in the storage means of different proportions and the temperature of the liquid in each said compartment means and available for supply to the associated zone may therefore be independently regulated.
2. The multiple zone heating installation of claim 1, together with a controller for positioning each of said flow dividing means to thereby determine the proportioning of flow by said divider between the main body of liquid in the storage means and the compartment means with which the flow dividing mean is associated, each said controller having a temperature responsive sensor in the Zone of the heat using means with which the flow dividing means controlled thereby is associated.
3. The multiple zone heating installation of claim 1:
(a) wherein said heat transfer medium is a solid at nor- -mal ambient temperatures; and
(b) including an auxiliary system for liquefying the heat transfer medium comprising heat exchangers adapted to have a heated duid circulated therethrough so disposed in the storage means as to heat the main body of heat transfer medium therein and in each of said compartment means so as to heat the medium in the compartment, means for heating said uid, and Imeans including supply and return conduits connecting said fluid heating means to said heat exchangers.
4. The multiple zone heating system of claim 1, whe-rein each of said compartment means is thermally insulated from the main body of heat transfer medium in the storage means therefor.
5. A multiple zone heating system, comprising:
(a) storage means containing a heat transfer medium adapted to be circulated in liquid form;
(b) heating means for maintaining the main body of heat t-ransfer medium in said storage means substanitally at a given temperature level;
(c) multizone heat using means;
(d) a separate compartment in said storage means for each zone of the heat using means from which the liquid supplied to said zone is withdrawn;
(e) a system for circulating the heat transfer medium from the compartments in the storage means to the zones of the heat using means with which they are associated; and
(f) means for regulating the temperature of the heat transfer liquid supplied to each of said zones independently of the temperature in the other compartments and independently of the main body of liquid in the storage means, said last-named means including, for each zone of the heat using means:
(1g) means operably associated with the compartment in the storage means for the zone for supplying relatively cool liquid -returned from the zone and relatively hot liquid from the main body of liquid in the storage means to said compartment to maintain a body of liquid therein; and
(h) means for controlling the proportion of cool to hot liquid thus supplied to said compartment and thereby governing the temperature of the liquid in said compartment and available for supply to said zone.
6. The heating system of claim 5, wherein the temperature regulating means associated with each of said zones comprises means on the supply side of said circulation system for mixing rela-tively hot liquid from the liquid heating means with relatively cool liquid returned from the zone to thereby govern the temperature of the liquid available for supply to the zone.
7. The heating system of claim 5:
(a) wherein said heat transfer means is a solid at normal ambient temperatures; and
(b) including an auxiliary system independent of said heating means and having heat exchange means in said storage means for liquefying said heat transfer medium during start-up of the heating system.
8. The heating system of claim 5, wherein said proportion controlling means comprises temperature sensing means in the zone and fluid -directing means operatively connected thereto `and capable of diverting varying proportions of the returning fluid into said compartment to thereby regulate the proportion of returning fluid delivered to said compartment and therefore the proportion of cool to hot liquid as the temperature detected by said sensing means changes, whereby the temperature of the liquid in the compartment and available for supply to the zone may be increased and decreased as the sensed temperature changes -to compensate for'changing heat demands in said zone.
9. The heating system of claim 5, together with:
(a) means for circulating the heat transfer medium between the storage means and the liquid heating means; and
(b) separate means operable independently of each other and of said last-mentioned circulating means for circulating said heat transfer medium to each said heating zone and for returning it to said storage means.
10. A multiple zone heating installation, comprising:
(a) storage means containing a body of heat transfer medium adapted to be circulated in liquid form;
(b) means for maintaining the body of heat transfer medium in said storage means substantially at a given temperature level;
(c) multizone heat using means;
(d) compartment means for each of said zones, the interior of each said compartment means being in uid communication with the main body of liquid in said storage means; whereby said liquid can flow into said compartment means as liquid in said compartment means is withdrawn therefrom;
(e) a circulation system for supplying liquid from each said compartment means to the associated zone of the heat using means and for returning the liquid thus supplied to said storage means; and
(f) independently adjustable means for dividing the liquid returned from each said zone between the compartment means from which the liquid was supplied and the main body of liquid in the storage means;
(g) whereby the liquid supplied to each said compartment means may constitute a mixture of relatively cool liquid returned from the associated zone and relatively hot liquid from the main body of liquid in the storage means of different proportions and the temperature of the liquid in each said compartment means and available for supply to the associated zone may therefore be independently regulated.
References Cited UNITED STATES PATENTS 1,586,987 6/1926 Govers 126-378 2,006,193 6/ 1935 Bell 237-56 2,153,382 4/ 1939 Martin 236-1 2,255,292 9/ 1941 Lincoln. v 2,295,149 9/ 1942 Adams et al. 236-1 2,490,932 12/ 1949 Thuney 237-8 2,491,576 12/1949 Oaks 237-8 2,910,244 10/1959 Payne 237-56 3,119,560 1/ 1964 Swaney 237-56 FOREIGN PATENTS 162,684 9/ 1933 Switzerland.
EDWARD J. MICHAEL, Prz'mwy Examiner.
Claims (1)
1. A MULTIPLE ZONE HEATING INSTALLATION, COMPRISING: (A) STORAGE MEANS CONTAINING A BODY OF HEAT TRANSFER MEDIUM ADAPTED TO CIRCULATED IN LIQUID FORM; (B) MEANS INCLUDING A FLUID HEATER AND A FIRST CIRCULATING SYSTEM COMPRISING A FLUID CIRCULATOR AND SUPPLY AND RETURN CONDUITS CONNECTING SAID FLUID HEATER TO SAID STORAGE MEANS FOR MAINTAINING THE BODY OF HEAT TRANSFER MEDIUM IN SAID STORAGE MEANS SUBSTANTIALLY AT A GIVEN TEMPERATURE LEVEL; (C) MULTIZONE HEAT USING MEANS; (D) COMPARTMENT MEANS IN SAID STORAGE MEANS FOR EACH OF SAID ZONES, THE INTERIOR OF EACH SAID COMPARTMENT MEANS BEING IN FLUID COMMUNICATION WITH THE MAIN BODY OF LIQUID IN SAID STORAGE MEANS, WHEREBY SAID LIQUID CAN FLOW INTO SAID COMPARTMENT MEANS AS LIQUID IN SAID COMPARTMENT MEANS IS WITHDRAWN THEREFROM; (E) A CIRCULATION SYSTEM COMPRISING SUPPLY AND RETURN CONDUITS AND A CIRCULATOR FOR SUPPLYING LIQUID FROM EACH SAID COMPARTMENT MEANS TO THE ASSOCIATED ZONE OF THE HEAT USING MEANS AND FOR RETURNING THE LIQUID THUS SUPPLIED TO SAID STORAGE MEANS; AND (F) INDEPENDENTLY ADJUSTABLE, FLOW DIVIDING MEANS FOR DIVIDING THE LIQUID RETURNED FROM EACH SAID ZONE BETWEEN THE COMPARTMENT MEANS FROM WHICH THE LIQUID WAS SUPPLIED AND THE MAIN BODY OF LIQUID IN THE STORAGE MEANS; (G) WHEREBY THE LIQUID SUPPLIED TO EACH SAID COMPARTMENT MEANS MAY CONSTITUTE A MIXTURE OF RELATIVELY COOL LIQUID RETURNED FROM THE ASSOCIATED ZONE AND RELATIVELY HOT LIQUID FROM THE MAIN BODY OF LIQUID IN THE STORAGE MEANS OF DIFFERENT PROPORTIONS AND THE TEMPERATURE OF THE LIQUID IN EACH SAID COMPARTMENT MEANS AND AVAILABLE FOR SUPPLYING TO THE ASSOCIATED ZONE MAY THEREFORE BE INDEPENDENTLY REGULATED.
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US574398A US3329344A (en) | 1966-08-23 | 1966-08-23 | Multiple zone heating system |
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US574398A US3329344A (en) | 1966-08-23 | 1966-08-23 | Multiple zone heating system |
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US20110006125A1 (en) * | 2007-11-15 | 2011-01-13 | Uponor Innovation Ab | Controlling under surface heating/cooling |
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CH162684A (en) * | 1931-02-16 | 1933-07-15 | Sulzer Ag | Hot water heating system with circulation pump. |
US2006193A (en) * | 1932-06-10 | 1935-06-25 | Edward J Bell | Heating system |
US2153382A (en) * | 1935-06-22 | 1939-04-04 | Gen Electric | Zone heating system |
US2490932A (en) * | 1945-05-31 | 1949-12-13 | Honeywell Regulator Co | Control apparatus |
US2491576A (en) * | 1945-08-11 | 1949-12-20 | Thermal Liquids Inc | Liquid heating system |
US2795149A (en) * | 1953-10-05 | 1957-06-11 | Beaver Prec Products Inc | Ball-bearing screw assembly |
US2910244A (en) * | 1955-09-20 | 1959-10-27 | Pierce John B Foundation | Heat transfer method and apparatus |
US3119560A (en) * | 1957-11-05 | 1964-01-28 | Swancy Robert Casper | System of proportional recirculation and zone control using liquid heat transfer media in paper driers |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5775581A (en) * | 1996-09-24 | 1998-07-07 | Welden; David P. | Dual heat source heating system |
US20110006125A1 (en) * | 2007-11-15 | 2011-01-13 | Uponor Innovation Ab | Controlling under surface heating/cooling |
US10488057B2 (en) * | 2007-11-15 | 2019-11-26 | Uponor Innovation Ab | Controlling under surface heating/cooling |
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