US 3210005 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Oct. 5, 1965 G. D. ARNOLD STEAM HEATING SYSTEM Filed Nov. 15, 1962 United States Patent O 3,210,005 STEAM HEATING SYSTEM George D. Arnold, Peru, lind., assigner to The Dewey- Shepard Boiler Co., Inc., Peru, 1nd., a corporation of Indiana Filed Nov. 13, 1962, Ser. No. 237,178 1 Claim. (Cl. 237-7) This invention relates generally to steam heating systems of the type comprising a boiler and a radiator connected thereto, and more particularly to a unitized steam heating system wherein a single radiator is rigidly secured to a boiler by the interconnecting piping so that the system may be transported and installed as a unit.
Conventional steam heating systems employ a number of radiators each having a steam inlet at one end and a condensate outlet at the other end, the steam inlet of each radiator being connected to a steam supply line and the condensate outlet being connected to another line which returns the condensate to the boiler. Thus, in such conventional steam heating systems, each radiator forms a serially connected part of a condensing system.
The eciency of heat transfer between one `medium and another is dependent, among other things, upon the duration of the exposure of the heated medium to the heat transferring medium. In conventional steam heating systems, the steam in the radiator is continuously flowing from the inlet toward the outlet and thus, a given unit quantity of steam is exposed to a given incremental surface 4area of the radiator for only an infmitesimally small period of time. The efficiency of heat transfer can therefore be improved by exposing a given quantity of steam to a given surface area of the heat transfer medium for a longer period of time; this improvement can be obtained however only in the absence of condensation of the steam which would thus cool the heat transfer medium. Thus in a steam heating system, the efficiency of heat transfer would be substantially increased by filling the radiator with steam, without continuously circulating the steam therethrough, insuring however that no condensation takes place in the radiator. However, such an arrangement has been thought to be inconsistent with the closed cycle condensing steam system required for the efficient generation of superheated steam. Furthermore, formation of condensate in the radiator has been believed to be inherent and its removal has been thought to be difficult.
In addition to the foregoing, conventional steam heating systems have comprised a plurality of radiators fed from a central boiler, the system thus necessitating extensive .and thus costly high-pressure steam lines and condensate return lines. There are many installations such as small homes, motels, and the like, where the expense of conventional steam heating systems is not warranted and this has lead to the development of small unitized hot air space heaters, generally oil or gas fired. Such space heaters, while relatively inexpensive to purchase and install, do not possess the relatively high efficiency of a steam heating system. Miniature electrically tired steam boilers are now commercially available and it is therefore desirable to provi-de a unitized space heater incorporating a steam radiator in conjunction with such a boiler thereby gaining the increased eliciency of a steam heating system.
It is accordingly an object of the invention to provide an improved steam heating system.
Another object of the invention is to provide an improved steam heating system having higher eciency than conventional steam heating systems.
A further object of the invention is to provide an improved steam heating system of the closed cycle condensing type wherein steam is neither circulated through the radiator nor condensed therein.
Yet another object of the invention is to provide a unitized boiler and radiator assembly.
Further objects and advantages of my invention will become apparent by reference to the following description and the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claim annexed to and forming' a part of this specification.
The invention in its broader aspects provides a water boiler and means for heating the water therein thereby to generate the steam, the boiler having a steam outlet above the water line and a condensate return inlet below the water line. Condensing means is provided interconnecting the steam outlet and the condensate inlet and a radiator is provided dening a closed chamber having a steam inlet only communicating therewith. The steam inlet of the radiator is connected to the condensing means for receiving steam therefrom and to be continuously filled thereby. With this arrangement, substantially all of the condensation takes place in the steam inlet of the radiator means and the continuous ow of steam in the condensing means provides an aspirating effect with the steam inlet thereby removing the condensate therefrom, with the result that the radiator means is continuously lled with super-heated dry steam.
In the preferred embodiment of the invention, the radiator means is immediately adjacent the boiler and is rigidly attached thereto by the condensing means thereby to provide a unitized assembly.
The single ligure of the drawing schematically illustrates the improved unitized steam heating system of the invention.
Referring now to the drawing, the steam heating system of the invention, generally indicated at 1 comprises a steam boiler assembly 2, a radiator assembly 4 and a condensing assembly 6 which rigidly attaches the radiator 4 to the boiler 2 to provide a unitized assembly.
Boiler 2 is preferably conventionally fabricated with a vertically disposed cylindrical shell 8 and top and bottom heads 10 and 12. It will be understood that suitable stay bolts together with suitable lagging (not shown) will be provided, as is well known to those skilled in the art. An electrically energized immersion heater 14 is shown extending into the boiler 2 adjacent the bottom head 12 for heating the water 16 therein. Immersion heater 14 is inclined upwardly at an angle with respect to the bottom head 12, preferably on the order of 45, and is surrounded by a tubular sleeve 17 secured to the inner surface of the shell 8 by Welding, as at 1S. Sleeve 17 is opened at its outer end 20 and also has an opening 22 formed at its inner end, thereby providing for the circulation of water over the surface of the heater 14 from the opening 22 toward the opening 20. This circulation of water over the heating element 14 rapidly extracts heat therefrom thus preventing it from becoming overheated and further tends to prevent the deposit of lime or scale on the heating element. It will be understood that a plurality of such immersion heaters may be employed.
A conventional pressure control switch 24 is provided serially connected with the electrical leads 26 of the heater 14 and having a pressure-sensing element 28 extending into the boiler for sensing the steam pressure therein. It will be understood that leads 26 of the heating element 14 are adapted to be connected to a suitable source of energizing potential. It will further be readily understood that the boiler 2 will conventionally be provided with a water inlet for admitting water to the boiler as needed,
a pressure gauge for observing the steam pressure in the boiler, and a water gauge for observing the water level in the boiler. 1t will further be understood that the heater 14 when energized heats the water 16 in the boiler 2 caus- Ving it to boil thus generating steam in the upper portion 30 of the boiler, as indicated by the dashed arrows 32.
The shell 8 of the boiler 2 is provided with a steam outlet 34 adjacent the top head 10 and well above the water line 36 of the water 16, and a condensate return inlet 38 adjacent the bottom head 12 and well below the water line 36. The condensing assembly 6 comprises a steam Afeed conduit having a rst section'40 and a second section 42. The first section 40 of the steam feed conduit has its lower end 44 connected to the steam outlet 34 of the boiler 2 in any suitable manner, as by elbow 46 and nipple 48, the steam feed conduit section 40 extending vertically upwardly in spaced-apart relationship with the boiler shell 8 to a point spaced above the top head 10. Steam feed conduit section 42 has one end 50 connected to the upper end 52 of the conduit section 40 in any suitable manner, as by a union 54, makes a right angle bend, `as at 56, and extends substantially horizontally across top head of boiler 2 and vertically spaced therefrom. Steam feed conduit 42 then makes another right angle bend S8 and extends vertically downwardly to its end 60.
A condensate return conduit is provided having sections 62 and 64. Condensate return conduit section 62 has one end 66 connected to end 60 of steam feed conduit section 42 in any suitable manner as by union 68. Condensate return conduit section 62 then makes a right angle bend 70 and extends generally horizontally across top head 10 of boiler 2, being vertically spaced thereabove and below steam feed conduit section 42, as shown. Condensate return conduit section 62 then makes another right angle bend 72 and extends vertically downwardly to its end 74. A slight drop is preferably provided in condensate return conduit section 62 between bends 70 and 72 in order to permit the condensate to drain downwardly into condensate return conduit section 64.
Condensate return conduit section 64 has its upper end 76 connected to the lower end 74 of conduit section 62 in any suitable manner, as by union 78, and extends vertically downwardly in spaced-apart relationship with shell 8 of boiler 2. The lower end 80 of condensate return conduit 64 is connected to condensate inlet 38 of boiler 2 in any suitable manner, as by elbow 82 and nipple 84. It will be seen that steam feed conduit section 42 and its end 60, and condensate return 62 and its end 66 have a larger inside diameter than steam feed conduit section 40 and condensate return conduit section 64. It will also be seen that water 86 will rise in condensate return conduit section 64 to the level 36 of the water 16 in the boiler 2, however the water 86 in the conduit section 64 will not boil by virtue of its isolation from the heater 14, and also by virtue of the fact that relatively cooler condensate is continuously falling therein.
It will be seen that steam 32 in the upper portion 30 of boiler 2 will enter steam outlet 34 and steam feed conduit section 40, as shown by the dashed arrows 88. By virtue of the larger inside diameter of conduit sections 42 and 62, a lower static pressure will exist therein which draws the steam toward these sections as shown by the dashed arrows 90. Conduit sections 42 and 62 are not thermally insulated and thus, as the steam reaches end 60 of the steam feed conduit 42, it will begin to condense as shown by the solid arrows 92. The condensate will then llow downwardly in condensate return conduit sections 62 and 64 back to the boiler 2, the arrangement thus providing a continuous condensing cycle of steam entering condenser assembly 6 from the boiler, being condensed therein, and being returned to the boiler as condensate.
Radiator 4 is shown as being a conventional steam radiator of the tube and fin variety, and thus comprises Cil top and bottom headers 96, 08 interconnected by a plurality of tubes which extend through fins 102, as is weil known to those skilled in the art. Headers 96, 98 respectively have openings 101, 103 formed therein to which a steamline and condensate return line are respectively connected in a conventional steam heating system. 1n accordance with the invention, however, opening 103 in header 93 of radiator 4 is connected to opening 107 in the steam feed conduit section 42 approximately midway between its ends 56, 58 as by a suitable nipple 104 and union 106, while the opening 101 in header 96 is normally closed by a conventional bleeder valve 108. A conventional fan is provided driven by motor 112 for blowing air across the ns 102 and tubes 100, as shown by the arrows 114.
In operation, the boiler 2 is initially charged with water and is fired electrically by immersion heater 14 which heats the water directly, thereby to boil the same. As steam is generate-d, it expands to ll the space 30 above the water line 36 in the boiler 2 and expands into the steam feed conduit 40, 42 and into the closed chamber defined by the tubes 100 and headers 96, 98 of the radiator 4; bleeder valve 10S is actuated initially in order to bleed air from the system as it lls with steam. As the steam pressure increases, the temperature of the steam increases proportionally thereby to provide superheated steam. The steam expanding into the steam feed conduits 40, 42 also expands into the condensate return conduit 62 where it begins to condense, the condensate returning to the boiler by gravity, thus initiating the condensing cycle. When the initial steam pressure at opening 103 in header 98 of radiator 4 equals that in steam feed conduit 42 at opening 107, no further steam will enter the radiator and all of the steam generated will momentarily be circulating in the condensing circuit.
lt will now be seen that initially, a body of steam is injected into the closed compartment defined by the tubes and headers of the radiator 4, which steam remains, without flow through the radiator, continually exposed to the heat transferring elements, i.e., the interior walls of the tubes 100. As heat transfer takes place, however, the temperature of the steam within the radiator 4 is reduced thus reducing its pressure and providing some condensation, which however it is believed takes place in the short neck section formed by nipple 104 and union 106. As soon as the pressure within the radiator 4 is reduced below that prevailing at opening 107 on steam feed conduit section 42, more steam will enter radiator 4 to equalize the steam pressure, the flow of steam in the steam feed conduit 42 passing opening 107 therein which is connected to opening 103 in header 98 of radiator 4 providing an aspirating action which removes the condensate from the neck section, the thus aspirated condensate being entrained in the steam flowing in the steam feed conduit 42.
It will be seen that since a given quantity of steam remains in radiator 4 for a substantial period of time, the heat transfer to the tubes 100 is considerably more efcient than would be the case with the steam rapidly flowing therethrough. Further, it is seen that any tendency for the steam pressure within the radiator to drop as a result `of the tendency to lower its temperature due to the heat transfer is immediately accompanied by injection of a small quantity of new steam thus maintaining the temperature of steam in the radiator at essentially that prevailing at opening 107 in steam feed conduit section 42, which in turn will be only slightly less than that prevailing in the boiler 2. The steam in radiator 4 thus remains continuously superheated, there being no condensate forming on the walls of the tubes 100 to cool the same.
Directly connecting radiator 4 to the boiler 2, or con necting it to a point on the condensing system 6 at which condensation has already begun to take place will result in the boiler priming or lling up the radiator with saturated steam or condensate, thus greatly lowering the eiciency of the system.
In a specific embodiment of the invention having a boiler 2 accommodating approximately 11/2 gallons of Water, conduit sections 40, 64 and 84 were formed of 1 inch (inside diameter) pipe and conduit sections 42 and 62 were formed of one and one quarter (1%) inch pipe, the short neck section extending from opening 107 in conduit section 42 to opening 103 in radiator header 98 likewise having an inside diameter of one and one quarter (1%) inches. In this embodiment, conduit section 42 was disposed six and one-half (6l/2) inches above top head 10 of boiler 2 and had an overall length of fteen and one-quarter inches, there being seven and three-quarters (7%) inches between bend 56 and opening 107 and 6 inches between opening 107 and bend 58. Conduit section 62 was disposed two (2) inches below conduit section 42 and had an overall length of sixteen and three-quarter (163/4) inches with a one quarter (1/4) inch drop between bends 70 and 72.
Radiator 4 had a heating surface of .80 square foot and was connected to conduit section 42 as closely as possible, i.e., the bottom surface of header 98 being approximately one and one-half (l1/z) inches above conduit section 42 in the specific embodiment. With this arrangement and with the pressure control switch 24, 28 set to provide a boiler pressure of 85 lbs. per square inch, superheated steam at 320 F. is provided in boiler 2, the temperature of conduit section 42 at opening 107 being approximately 310 F. and the temperature of the exterior of tubes 100 of the radiator 4 adjacent the top header 96 having been found to be 292 F.; this exterior temperature of tubes 100 clearly indicates that no condensation is taking place therein. With fan 110 providing air flow at the rate of 500 to 900 cubic feet per minute, the temperature of the air leaving radiator 4 immediately adjacent the side thereof remote from fan 110 was found to be 250 F. at a pressure of 6 inches of mercury, with the heating element 14 injecting 37,000 B.t.u. heat units into the water in the boiler.
It will be seen that the radiator 4 is supported immediately above and rigidly connected to the boiler 2 by the condensing assembly 6 thereby providing a compact, unitized, readily transportable assembly. It will be readily understood that conventional duct Work may be connected to the radiator 4, thus making the system suited for use as a furnace for motel rooms, smaller homes, and the like, the system providing the desirable features of both steam and electric heating.
While I have illustrated and described a specific embodiment of my invention, further modifications and improvements will occur to those skilled in the art and I desire therefore in the appended claim to cover all modications which do not depart from the spirit and scope of my invention.
What is claimed is:
A steam heating system comprising:
(a) a steam boiler accommodating Water at all times,
(1) said boiler having a steam youtlet above the water line therein and a condensate return inlet below the water line;
(b) immersion heating means in said boiler below the water line for heating said water to generate steam,
(c) steam pressure control means coupled to said heating means,
(1) said heating means and control means being proportioned and arranged continuously to provide high pressure superheated steam in said boiler;
(d) a closed cycle steam condensing line having one end connected to said steam outlet and its other end connected to said condensate inlet for continuously circulating steam and condensate therebetween,
( 1) a rst portion of said steam line adjacent said steam outlet having superheated Steam only therein and a second portion connecting said first portion to said condensate inlet having condensate therein,
(2) said first portion of said steam line including a first straight section;
(e) a single radiator defining a closed chamber and having a single common steam inlet and condensate drain opening communicating therewith;
(f) and a T-connection of minimum length coupling said radiator opening and said first section of said steam line intermediate its ends for receiving superheated steam therefrom and for continuously filling said chamber with superheated steam,
(g) said first section of said steam line and said connection forming an aspirator whereby the flow of steam in said steam line removes condensate from said radiator,
(h) said T-connection being the sole connection to said steam line between said steam outlet and condensate inlet;
(i) said boiler, said heating means, and said first portion of said steam line being proportioned continuously to supply superheated steam to said T-connection and said radiator during dissipation of heat therefrom.
References Cited by the Examiner UNITED STATES PATENTS EDWARD I. MICHAEL, Primary Examiner.
FREDERICK L. MATTESON, JR., JAMES W. WEST- HAVER, Examiners,