US2630789A - Heat transfer system - Google Patents

Description

March 10, 1953 W, R, SMlTH. 2,630,789

HEAT TRANSFER SYSTEM Filed July 7, 1948 M e sheets-sheet 1 EQ2 i March 10, 1953 WQR. SMITH 2,630,789

HEAT TRANSFER SYSTEM Filed July '7, 1948 6 Sheets-Sheet 2 n@ 25@ ii ni' March 10, 1953 w. R. SMITH HEAT TRANSFER SYSTEM 6 SheetsFSheet 5 Filed July '7, 1948 March 10, 1953 w. R. SMITH HEAT TRANSFER SYSTEM 6 Sheets-Sheet 4 Filed July 7, 1948 o o We `March 10,1953 w. R. SMITH HEAT TRANSFER SYSTEM 6 Sheets-Sheet 5 Filed July 7, 1948 Patented Mar. 10, 1953 HEAT TRANSFER SYSTEM Wilbur R. Smith; Allentown, Pa., assignor tu` Bethlehem*` Foundry & Machine Company.,- Bethlehem, Ba., a corporation,` of Pennsylvania.

Application July 7, 1948`, Serial No. 37,451

2 claims.

This inventionrelates to heat transfer apparatus and more particularly'to apparatus utilizing a high temperature salt or like agent as the heat transfer medium. Such salt medium may consist, forexample, of a mixture of 50% sodium nitrate and 50% potassium nitrate. It freezes at about 282 F.; and may be used at atmospheric pressures in the liquid state in the temperature range of about 300 F. to 1000 F.

A primary object ofthe invention is to provide a` heat transfer system including a heating unit or boiler structurally adapted to the use of a thermal transfer medium of thestated type.

A more specic object ofthe invention is to provide a heating unit for thermal transfer systems ofthe stated character wherein adequate provision is made for relative expansion and contraction of the elements of` the; heater structure under the Wide temperature variations experienced in the opera-tionnof a system of this character.

Another object of the invention is to provide a thermal transfer system of the stated type including a chamber for storage of the hightemperature transfer mediumv having novel and effective means for application of heat to said medium for conversion thereof from they solid to the liquid state.

The invention resides vfurther in certain novel structural details contributing;l to the adaptation of' the heating unit and of the related parts of the system to the use ofthe aforesaidthermal transfer medium, said details being hereinafter described and illustrated in the attached drawings, wherein:

Fig. 1 is a sideY elevational view partly in section ofi the heating section of a system made in accordance with the invention;

Fig. 2 is a top plan view also partly in section of the apparatus illustrated in Fig. l;

Fig. 3 is a rear elevational vieW ofthe heating unit of said system;

Fig. 4 is a front elevational View partly inY section of said unit;

Fig. 5 is a vertical sectional View on the lin 5--5l Fig. 2:

Fig. 6 is a transverse sectionalview on the line 6-6 Fig. 1;

Fig. '7 is a vertical sectional view on the line T--T Fig. 5;.

Fig. 8 is a fragmentary sectional View illustrating a. detail ofthe heater unit structure;

Fig. 9' is a section on the liner-9, Fig. 8;

Fig. 10 is` a view in perspective of one.. of the 5 tube unitsof the heater;

Fig. l1 is a section on the line Ij-HY Fig ."2, and

Fig. 12 isa view in perspective of theporton-of the apparatus shown: in Fig. 1l.

With reference to the drawings, a, thermal transfer system constructed in accordance with theinvention may comprisev a boileror heating unit I, including a chamber 2vfor storage ofthe high temperature transfer medium, a combustion chamber 3, Within which the said medium is heated vto a desired temperature, anda pipe system 4' through` Which the mediumxi's circula-ted for'transfer of the contained heat'tora desired area or apparatus. The storage chamber 2 is contained within a suitable casing 5 Within which is mounted an L- shaped bank 6 of steam tubes 1, said tubes extending ln proximity to one side and along the bottom of the chamber as best shown in Fig; l. At the upper end of the bank the tubes-f1 are connected to a manifold 8 and this manifold is connected to a source of steam (not shown) 'by means of'pipe 9 Which extends upwardly through an inner horizontal Wall II of the tank and through a relatively spaced top Wall` I2. The opposite ends of the pipes 'I' are connected to a manifold I 3 from one end'of which a pipe` I4 extends to the outside of the tank for connection to an exhaust or return duct I5, see'Fig. 2. 'i

Supported in the walls II and I2 of the tank is a pump I6 which extends to the bottom area of the chamber 2 and which includes a pair Gf discharge ducts Il, I"I which extend upwardly through the inner Wall II and are connected to Aa manifold i8 Withinv the space between the' said inner wall and thel top Wallv I2. The pumpr I6 isk actuated by motor I9 supported on a suitable bracket 2I at the top of the tank 5. From the manifold I8, a series of pipes 22 extend through the insulated Wall 23 ofthe combustion chamber 3', each to an individual header 2li supported in the bottom of the combustion chamber upon suitable `pedestal supports 25. The pipes 22 are connected to the proximate ends of the respective headers 24, which in the present instance are six in number, as best illustrated in Figs. 6 and 7. The said headers extendv in closely spaced relation from the said front Wall 23 of the combustion chamber to the rear wall 26 and jointly occupy substantially the entire ltransverse area ofthe chamber 3 with the exception of space occupied by a burner 21 which extendsupwardly through the bottom Wall 28 ofthe combustion chamber. In `the `present instance. the burner is of the oil-fired .,type. ,A

From each of the headers 24, a plurality of tubes 3| extend upwardly through the chamber 3 to a corresponding series of upper headers 32, from the forward end of each of which a duct 33 extends upwardly through the -top Wall 34 of the combustion chamber for connection with a manifold 35 which overlies the too of the wall. From the manifold 35. two tubes 3B and 31 extend upwardly for connection respectively with ducts 38 and 39, the duct 38 extending downwardly through the top and inner walls l2 and Il of the tank to the top of the chamber 2, and the duct 39 constituting one of the elements of the circulatory heat transfer system. This svstem comprises also a return duct 4l which passes to the top oi the chamber 2 as shown in Fig. 2.

It will be apparent that the liquid medium drawn from the storage chamber 2 by the pump I6 will pass to the headers 24 upwardly through the tubes 3| within the combustion chamber 3 to the upper headers 32, and thence to the system pipe 39, said licuid, after transfer of its heat, returning by way of the pipe 4| to the chamber 2. Flow of the licuid from the manifold 35 is controlled by diaphragm valves 42 and 43 associated respectively with the by-pass duct 3B and the system duct 39. These valves may be of standard diaphragm pressure-control type adapted for automatic operation. the valve 42 being normally open and closing by air pressure on the valve diaphragm. The valve 43 is normally closed and is opened by air pressure on the valve diaphragm. The valve 43 is provided with a hand wheel 44 for manual operation, so that this valve may be opened in case of air or electrical failure. While the salt medium is being heated to the desired operating temperature valve 43 is closed and valve 42 is open. When the salt reaches the desired operating temperature, valve 42 is closed and valve 43 is opened to duct 39.

The elements of the tube system, consisting of several units each comprising one of lower headers 24, a corresponding upper header 32 and the connecting tubes 3l are mounted in the comwith respect to the lower headers 24, are supported primarily by the tubes 3l so that these headers also are free for longitudinal expansion. The pipes 33 which extend upwardly from the forward ends of the headers 32 through the top wall of the re box, while to some extent anchoring the forward ends of the headers in substantially the same manner in which the forward ends of the lower headers 24 are anchored by the pipes 22, are free to move vertically in the upper wall 34 so that the tube units are in each case free to expand and contract vertically, ample clearance being provided between the inner surface of the top wall 34 and the respective headers 32 for such expansio-n.

The valves 42 and 43 are supported from the f tcp wall 34 in a manner providing for movements -of the valve structures with respect to said top Awall by reason of the aforesaid expansion of the tubes 3l. The support is illustrated in Figs. 11 and 12. It consists of a lever 45, one end of which is attached to a transverse shaft 46 which is journaled by means of trunnions 41 in the sides of a rectangular bracket 48 mounted on the top wall 34. The opposite end of the lever is supported by means of a pin 49 on the anges 5l of adjoining pipes 33. As the tube system expands and contracts in the re box 3 as described above, the lever 45 will be rocked about the axis of the trunnions 41. Pivotally connected at 52, 52 to the bracket 48 is a U-shaped lever 53. This lever comprises a transverse bar 54 which seats upon the lever 45. The free end of the lever 53 is connected by a composite link consisting of a pair of arms 55, 55 and transverse connecting elements 56, each of the arms having at its upper end a U-strap or clamp 51, which embrace the projecting ends 58 of the oasings of the respective valves 42 and 43. The lower ends of the arms 55 are pivotally connected at 59, 59 to the opposite sides of the lever 53. The valve is supported through the arms 55 upon the outer end of the lever 53 which in turn is supported through the crossmember 54 upon the lever 45. With this device, elevation of that end of the lever 45 which seats upon the flanges 5l will be accompanied by a corresponding elevation of the free end of the lever 53 to which are connected the arms 55. Since the arms form a solid connection between the lever 53 and the valves the latter will be afforded a constant support irrespective of the vertical expansion and contraction of the tube system within the fire box. Obviously the device also compensates automatically for any elongation of the pipes connecting the valves to the manifold 35. v

The vertical walls of the combustion chamber 3, which preferably are made of a plurality of detachable panels or vertical sections, are provided at each side of the chamber' with a normally closed clean-out opening El. In one side and near the top of the chamber the side wall is provided With an insulated pressure relief door 62, the detail construction of which is illustrated in Figs. 8 and 9. As therein shown, this insulated door is suspended from the top upon a hinge or hinges 63 set in recess 34 in the side wall of the chamber. The mass of the door is so disposed with respect to the hinge that gravity tends to swing the door inwardly about the hinge axis so that a gasket 65 in the door structure will engage the wall 66 of the combustion chamber around the blow-out opening 61 in which the door is mounted. The door is normally maintained in the closed position by its own weight but is otherwise free to swing outwardly under excessive pressure within the combustion chamber to thereby relieve the pressure to the atmosphere outside of the boiler. The door being insulated, heat loss is reduced to a minimum. It is to be noted with reference particularly to Fig. 6 that the vertical walls of the fire box are fully insulated as also are the top walls 34 and the bottom wall 28.

The front wall 23 of the combustion chamber is provided at its lower end with an opening 12 which communicates through a box 13 with a flue pipe 14, this nue being provided with a damper 15. 'I'hewall 23 also has an opening 16 near the top through which the chamber 3 also connects by way of a pipe 11 with the iiue 14, and a damper 18 is provided in the pipe 11 to normally close the connection of this pipe with the ilue. Under normal operating conditions and with the damper 18 closed as illustrated in Fig. 5, the hot combustion gases will follow the course indicated by the arrows circulating upwardly around the tubes 3i and downwardly through the front of the combustion chamber to the flue opening 72 and thence to the iiue 14. By opening the damper 18 these gases in Whole or in part may be diverted through the opening 16 to the flue pipe.

Assuming that the salt medium in the tank 2 has been permitted to cool to solidifying temperature, introduction of the steam into the tubes 1 will convert the salt to liquid state in preparation for circulation through the system. Since the salt is solid at atmospheric temperature, it is desirable that the entire system be constructed so that every part thereof will drain by gravity toward and into the tank 2. By reason of the L-shaped form of the heating tubes 1, liquecation of the solid salt will take place normally and rapidly with no possibility of excessive pressures arising from expansion of the liquefying salt in confined pockets within the tank. Thus, the horizontal and 'vertical sections of the tube bank 6 eilect liquecation of the solidified mass at the bottom and at one side of the tank from one side to the other and from top to bottom of the mass so that the melting salt has free access to the space above the salt mass within the tank 2.

Following liquefication of the salt, the pump I6 is set in operation to circulate the now liquid medium as previously described. By by-passing the salt in the initial stages of this operation through the pipe 38 to the top of the storage chamber 2, liquefcation of the solid salt in the latter will be facilitated and the temperature of the entire mass of salt raised rapidly to the required point. When the liquefied salt has in this manner reached the required elevated temperature, the by-pass 38 is closed and the system pipe opened for passage therethrough, of the heated medium, said medium still in liquid state returning to the storage chamber by way of the pipe 4I for reheating and recirculation through the system.

I claim:

1. A heating unit for circulating systems of the type set forth, said unit comprising an insulated combustion chamber, a tube assembly in said chamber forming a part of said system and mounted for contraction and expansion longitudinally of the tubes, a pipe connected to one end of said assembly and extending upwardly through the top wall of said chamber and movable longitudinally in said Wall with the expansion and contraction movements of said assembly, a manifold connected with the upper end of said pipe and a pair of ducts extending from said manifold, a valve controlling the connection of one of said ducts with the manifold and having a portion extending transversely with respect to said manifold, and means for supporting said transverse extension of the valve from said top Wall, said means including a lever system supported on said top wall and comprising lever elements each connected at one end to the said pipe and to the valve extension respectively, said elements being constructed and arranged so that a pivotal movement of one element due to movement of the pipe to which it is connected will be accompanied by an increasing rocking movement of the other of said elements connected to the valve extension.

2. A heating unit according to claim 1 wherein the said lever elements are disposed substantially parallel to said valve extension and are each pivotally supported on the top wall of the combustion chamber, the element connected to said extension being supported intermediate its ends upon the element which is connected to the pipe.

WILBUR, R. SMITH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 704,988 Vanstone July 15, 1902 1,634,084 Ruths June 28, 1927 1,659,836 Ruth-s Feb. 2l, 1928 1,680,931 Baker Aug. 14, 1928 1,682,674 Hedlund Aug. 28, 1928 1,757,343 Steinmuller May 6, 1930 1,877,762 Griswold Sept. 20, 1932 1,977,637 Kerr et al Oct. 23, 1934 2,160,262 Engels May 30, 1939 2,305,847 Digby Dec. 22, 1942 2,371,096 Zipetov Mar. 6, 1945 2,385,846 Seifert Oct. 2, 1945 FOREIGN PATENTS Number Country Date 307,425 France June 11, 1902 426,932 Great Britain Apr. 11, 1935 430,928 Great Britain June 27, 1935 444,368 Germany May 23, 1927

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