US2103178A - Steam heating system and method of supplying steam to the radiators thereof - Google Patents

Description

Dec. 21, 1937. R1. RAYMOND -STEAM HEATING SYSTEM AND METHOD OF SUPPLYING STEAM TO THE 'RADIATORS THEREOF 2 Sheets-Sheet 1 Filed March 22, 1934 Dec.21, 1937. F. l. RAYMOND 2,103,178 STEAM HEATING SYSTEM AND METHOD OF SUPPLY'I-NG STEAM TO THE RADIATORS THEREOF '2 Sheets-Sheet 2 Filed March 22, 1934 m W.) a a V/ w m 1 w gwmmg Patented Dec. 21, 1937 PATENT OFFICE STEAM HEATING SYSTEM AND METHOD OF SUPPLYING STEAM TO THE RADIATORS THEREOF Fred 1. Raymond, River'Forest, Ill.

Application March 22, 1934, Serial No. 716,914

6 Claims.

My invention relates primarily to steam heating systems, whether of the so-called steam, vapor, or vacuum type, comprising radiators in the several rooms of a building, a system of supply pip- 5 ing for conducting steam to each of the radiators from a central point, and a separate system of return piping for collecting the condensate from the several radiators and conductingit back to a desired point, my present invention being a continuation, in part, of my application for United States Letters Patent Serial No. 272,330, filed April 23, 1928.

One of my objects is to provide for the distributing of proportionate quantities of steam to the various radiatorsof a steam heating system of the so-called orificed type, at reduced capacities as well as at maximum capacity. While this object has been the object of previous systems of the so-called orificed type there are certain practical limitations in the apparatus that have hitherto been used which limitations have prevented the prior systems from accomplishing: the full measure of performance that I am able tosecure by my invention.

Another object is to provide for the distributing of the same proportionate quantities of steam to the radiators at the top of a tall building as to the radiators at the bottom of the building at all capacities, a result which has not been hitherto attempted so far as I can ascertain. Theneed for it arises out of the fact that the pressure differential tending to force steam into the radiators at the top of the building is greater than the differential at the bottom of the building'due to the buoyancy of the steam in the system of supply piping as compared with the heavier airin the system of return piping. This difference in difierential is most pronounced in tall buildings because the difierence in weight between the column of air in the return piping and the column of steam in the supply piping is directly proportional to the height of the column. This difference in differential between that at the top and that at the bottom of the building may be called the altitude head! It is a serious handicap in the operation of previous systems because it remains practically constant at all capacities and asthe differential in pressure is reduced for opera tion at lower capacities, the. altitude headbecomes an increasing proportion of the 'totaldif ferential.

As the differential in pressure is reduced, the point is finally reached where the difierential at the bottom of the building will be zero while the differential'at the top of the building will still'be equal to the altitude head. 'The seriousness" of this defect will be realized by considering the case of a building in which the top radiatoris 217- feet r higher than the bottom. Based on thedensity of saturated steam at 212 F. and. that of'dry air at 100 F. the altitude head would be equal to .1" of mercury. If the radiators of a system in such a building were equipped with orifices at the entrances to the radiators so sized that the radiators at the top and bottom'would each receive 100% of the desired quantities of steam when the diferential at the bottom'orifice'was 1.0" of mercury, then when the differential was reduced'by. throttling the supply of steam to the system to a point where the difierential at the bottom was zero, here would still be a difierential of .1" at the top radiator. This differential of .1" at the top orifice would produceapproximately 30% as much flow through the toprorifice as with the design differential of 1.1" for the top orifice forits rated capacity. Thus in such a system in a building 217 feet high, it would be necessary to supply 30% of the rated capacity of steam to the top radiator before any steam could bedelivered to the bottom radiator.

Some of the manufacturers of previous socalled orificed systems have realized this inherent limitation of altitude head, and have sought to minimize it by using a design differential much higher than 1'of mercury such as 2" or 4" and even 8" and. 10". By doing so they have been able to keep the altitude head a much smaller proportionof the total head. However, atthese higher diiferentials, the velocity of the steam through the orifices is so great that it causes a hissing sound which is audible in the rooms and objectionable for that reason. 7

Another limitation of previous orificed SYS". terms, which limitation I overcome by my invenftion, arises out of the fact that the flow of steam through an orifice is substantially proportional to the square root of the pressure differential 1, 19,7 5 the orifice. Thus the quantities of steam which will flow through an orifice designed to give 100% of capacity at 1" diiferential are as follows:

Pressure Percent differential oi flow l. 0 Hg 100 From the above table it is evident that the differentials required at low capacities are very minute quantities. Not only is extremely accurate and sensitive pressure controlling apparatus required, but it also becomes extremely diificult to produce these same pressure diiferentials or the same relative pressure differential in all parts of the system. While it is theoretically possible to place additional orifice plates in the branch steam lines of such a system and thereby correct for drop in differential due to difierent sizes and lengths of the supply pipes, it becomes an extremely delicate and tedious operation in actual practice. Moreover, even after all corrections have been made for resistanceto flow in the supply piping, the defect of unequal fiow due to altitude head still remains.

The first referred to object of my invention can be best understood by comparing the following table of pressure difierentials at which I might choose to operate my system with the table of pressures given above.

Percent of flow Pressure difierential By comparison it will be noted that for 20% capacity with my system, I would require a differential of .2" Hg as opposed to .04 Hg under previous systems. The differential would be five times as great with my system as in previous systems at 20% of capacity provided both systems were designed to give 100% flow at the same differential. Similarly, my system would employ ten times as much differential at 10% of capacity as previous systems. Because of this greater differential at reduced capacities, the pressure controlling apparatus would not need to be nearly so sensitive as with previous: systems. Also the efiect of piping resistance would be of much less importance. Also there would be considerable advantage from the standpoint of instructing an operator to have a system in which twice as much pressure differential would give twice as much flow. It would be simpler too to build controlling apparatus which operated to produce pressures directly proportional to required capacities than it is to build controls to operate on a square root basis of increment.

My approach to the accomplishment of the second object of my invention can be best understood by reference to the example previously given of .1" Hg altitude in a building 217' high. In that example I pointed out that the .1 differential due to altitude head would produce approximately 30% flow through the top orifice while the flow at the bottom was zero. This defeet can be overcome if an orifice were installed in the upper radiator which would give 0% of flow at .1" pressure differential. Both the limitations of square root fiow and altitude head could be overcome if orifices were to be installed in the top and bottom radiators which would give the following performance:

Pressure Percent Pressure Percent difierential of flow at differential of [low at bottom bottom at top at top 1.0 Hg 100 1 1" Hg 100 .9 90 8 80 9 80 7" 70 8 70 6 60 7" 60 .5 50 .6" 50 4 4O .5 i0 3 30 4" 30 2 20 3 20 1" 1O 2 l0 .0 0 l 0 Having outlined my approach to a solution of the problem, it will now be simple to understand the means I have used.

I have obtained the first object of my invention by designing an orifice which automatically decreases in size by the proper amount as the pressure differential decreases. Thus I am able to decrease the flow through the orifice not only due to the reduced velocity of steam through the orifice due to reduction indifferential but also due to the reduction in size of the orifice.

I have attained the second object of my inven tion by designing an orifice which can be adjusted to be completely closed at any desired pres sure. Thus the orifice at the top radiator would be adjusted to be completely closed at .1" Hg differential in a building 217 feet high whereas the bottom orifice would be adjusted to be completely closed at 0 Hg differential.

Referring to the accompanying drawings:

Figure 1 is a view, in elevation,with parts broken away, of a heating system for a tall building and suitable for practicing my improved method.

Figure 2 is a view, in vertical section, of one form of radiator inlet valve which may be used, and of such construction as to be operated responsive to pressure differential at the inlet of the radiator.

Figure 2 is a fragmentary view of the valve of Fig. 2 modified to adapt it for use with a larger radiator.

Figure 3 is a similar view'of another form of radiator inlet Valve which may be used and of a construction operated by absolute pressure only; and

Figure 4, a similar view, with parts broken away, of a modification of the valve of Fig. 3 and desirable for use where low'pressure steam, or steam delivered under partial vacuum, is supplied.

Referring to the system shown, this system is an example of a steam heating system for a tall building in which an appreciable altitude head is encountered as above referred to, the radiators shown, a plurality of which are located on each floor of the building, being those which would be provided on the two lower and the two upper floors of ar:tall buildingnas 'abovesexplainemrthe mid section tofthe *radiator i'piping 'assembl c'being omitted.-

In this :system a. boiler indicated :at :5 isirrepresented" as nflredi by anixelectri'callyf driven" oil burner 6': shown as providedwith an adjustable pressure-controlled: :electr'ic switchi device 6 in:- terposed in series with the-motor 6 of: the burner B in the electric current lineawire's fi and fi the device 6 in accordance with common practice being adjustable to vary the steam pressure gen' erated in theboiler 5.

The boiler 5 connects by an upwardly extendingpipe I with. an overhead'main le 'from which steam-'is supplied tothelidown-feedsrisers' 'l 'fcon' stituting parts of the main 1 and: opening into the latter at different-points therealongas shown. Eachtriser l isi'showni as connected by' pipes l with a vertical series of radiators 8 each of which isprovi'ded with an inlet valve- 9 adjustable as hereinafter "explained to start to open-at-diifer ent pressures to:comp'ensa'te, as'aboveiexplaine'd, for'the altitude:head 'and for' the other purpose hereinafter explained, and ea'ch of which opens progressively at different rates toprovide'a particular relation, preferably a 1 straight-line relation, between the pressure and the quantities of steam entering. the radiators.

The system is shown'for the supplyingof steam to radiatorsa plurality'ofwhich are located on each floor of a building, the radiators shown being those which would be provided on the two lower and the two upper floors of a tall-building as'above explained;

Eachradi'ator 8- may be connected, as shown, at its outlet with a thermostatic trap valve H! which functions 'to permit the outflow of air and condensate from the radiators, but closes automatically to prevent the escape of steam therefrom. The traps lfiopenintoreturn line pipes H connected: with pipes: l2 communicating with a downwardlyextending pipe i3."

At the lower ends of the risers 1 are relatively large thermostatic traps I4* -connected with the return line pipes 12.

Preferably means'are provided for insuring the withdrawal of airandcondensate from the radiators through the return line pipes ll, 12 and I3 by the maintaining of a somewhat lower pressure in the return line than'thepressure in the radiators or'the feed pipes'conn'ected therewith. In the system shown such a meansis employed comprising a vacuum pump 15 driven-thy a motor is, the inlet of the pump communicating with an upstanding pipe I! which opens into the upper end of a condensate tank :18 into which the return line pipe l3 discharges. The tank I8 at its'bottom communicates with a pipe i9 which opens into'the-boiler 5' and through which the condensate is dischargedinto the boiler by a pump 20 interposed in the pipe l9 and driven by the motor l6.

As will be noted more in detail hereafter, the invention may be practiced where the heating medium is supplied at either high or low pressures, namely, in either a so-called pressure system or a vacuum system. If high pressure steam (that is, pressure above atmospheric) is used for supplying the radiators with steam, it may be desirable to maintain a super-atmospheric pressure in .the return piping H-l3 instead of exhausting the air fromthis piping, it being desirable that only a small difierential pressure be maintained between the supply risers and the radiators or return pipes.

Referring now to theiniet 'valves.--9"'for.i the 7 radiators; ands'whichmayzbex any one of aznum= ber of 'different forms as :for example asl'illustrated'in Figs-1:2,.2d, 3 and'4, the formzshown in Fi'gstZ and 2aiandwhi'ch. operates responsive to the difference between the pressure in the radiator1andlthe pressure irr'thesupply line, comprises a casing 24 presenting-a chamber- 2 5 havingjan inlet 26 connected with the pipe 1 and an outlet 21 connectedwith the inlet end 'oi the radiator. Located in the chamber-15' and: in spaced relation to the walls of the latter,"is a-flexible tubular metallic diaphragm 28 preferably of the expansible bellows typ'e as shown; with 'deeply'corrugated sidewalls, the lo'wer end-of the diaphragml 28 being rig-idly 'c'lainpedin'place, to'provide a pressuretight joint, between aring 29- and a disk-30 1oc'ated in the "chamber 25 andrigidly clamped in place to provide a sealed joint between sections of the casing; the diski3ilbein'g-sapertured as by providingthereina series of openings represented at3l toapermit oi the flow of the steam into the bellows-diaphragm. The upper end of the diaphragm 28I is closed by avalve plate 32'containing a central orifice 33 through which the steam supplied to the valve-device Qpasses to theradiatorunder the control of a valve located in the orifice 33 and represented at'34, the valve 34 be-' ing of general coneshape and shown as mounted for longitudinaladjustment relativeto'the orifice 33, as'byprovidingth'e valve "with a: depending stemlike 'portion 35 slidableinan opening in the disk 30. -It is desired that the valve 34-be held against"turningmovement and this is ef fected, intthe particular 'construction'shown, by forming the" stemlike portion 35- of non-circular shape'in cross section, as by cutting away the op posite sides of the lowerlcylindrical portion of the valve as- .shown,. an'd so shaping the opening 36 in: the "disk :30 as to prevent turning of the valve.

The valve 34 is further provided with an up wardly' extending stem portion 31' secured to an externally threadedinut 38 which engages the internal screw threads 39" of a valve stem 40: journalled: in ithecasing 24 andheld against longitudinal movement; whereby'the valve 34 may be adjustedlongitudinally of'the orifice 33 by ro= tating the stem 40.

From the above it will bexunderstood that the underside of thep'latec32 and the orifice '33 are subjected. tothe pressure of the steam supply and the top'surface of the'plate" 32 to the pressure in the radiator, the bellows diaphragm 1'8 acting as a spring tending to i hold the: bellowscollapsed.

Thus assumi'ngathat'thervalvestem 40. has been adjusted to a position iniwhich the plate .32 just contacts-at the wall of its orifice 33-with the sides of-thecome 34; when the steam pressure at opposite sides of the plate32 is. equal, the raising of the steam pressure in the supply line, or the reducing of: the pressurein the'radi'ator as by theoperation: of; the. vacuum pump I5; eitherof which builds up pressure in the-bellows 28, causes the:plate.32 to rise relative'to the cone and there by open the orifice 33proportionately to such movement-of the plate 32.

. Inthedesigning ofazsystem in. accordance with my. inventionxprovision would .be .made whereby the'openings'providedat the orificesfor the passagevofn' steam to the: radiators; whenthe conevalves cooperating therewith occupy their extreme open positionsresponsive-to the subjection thereof to thezmaximum'difierential pressure at which. it :isrdesignedthe:radiators operate at full capacity, would: be'of. such efiectiveness as to supply the respective radiators with the requisite amount of steam for the functioning of the radiators at their full capacity, it being understood that the larger the radiator the larger the efiective orifice in the full open position of the valve. The valve cones, from which the orifice plates move but a slight distance only in response to slight increase of pressure differential, would be so shaped that the amount of steam passing through the orifices is a substantially straight line function of pressure, rather than a hyperbolic function of pressure as in the case of non-variable orifices.

In practice I would prefer to equip all of the radiators with plates having orifices of the same size and compensate for different sizes of radiators by providing cones of different shapes, the larger radiators having cones of greater taper. This is illustrated in Figs. 2 and 2a wherein the valve of Fig. 2, provided for a radiator of approximately ordinary size, but smaller than that for which the valve of Fig. 2a is provided, would present less taper than the valve shown in Fig. 2a.

As will be understood, the valve 34 may be drawn up to set position in which the bellows 28 is under tension the degree of which determines the pressure at which the orifice initially opens, this being of advantage especially where different temperatures are to be maintained in different rooms, and also to compensate for altitude head in the particular heating system shown.

The valve as shown is provided on its stem 40 with stops 4| which extend into the path of upward movement of the orifice plate 32 and which form a backing for this plate permitting the operator to lift the valve 34 by manipulating the stem 40, into a position in which it presses upwardly against the wall of the orifice 33 with such pressure as to cause the valve to function as a stop valve preventing all flow of steam into the radiator.

The valve shown in Fig. 3 and which may be used at each radiator in place of a valve of the construction in Fig. 2 and of a type operating responsive to absolute inlet pressure, as distinguished from differential pressure, comprises a casing 42 divided in its lower portion by an internal apertured web 43 into an inlet passage 44 leading from an inlet port 45 and an outlet passage 46 leading to an outlet port 41, the ports 45 and 41 being coupled in. any suitable manner with the pipe 1 and the radiator 8, respectively. Mounted in the orifice in the web 43 is an orifice plate 48 containing the orifice 49 which'leads from the steam chamber represented at 50 to the outlet passage 46.

Located in the chamber 50 and in spaced relation to the walls of the latter is a flexible tubular metallic diaphragm preferably of the expansible bellows type, as shown, with deeply corrugated side walls, the upper end of the diaphragm which is open to the atmosphere as through a port 52 in the casing 42, being rigidly clamped in place between sections of the casing 42 to provide a sealed joint between the diaphragm and the sections of the casing. The lower movable end of the diaphragm 5| is provided with a valve 53 of general frusto-conical shape and cooperating with the orifice 49 to control the amount of steam passing through the latter responsive to the degree of pressure of the steam entering the chamber 44 through the inlet 45.

The valve also comprises a stem 54 rotatable, but held against longitudinal movement, in the casing 42, the lower end of the stem 54 being externally threaded as represented at 55 at which it is screwed into the internal threads 56 provided in an upwardly opening socket 51 in a nut 58 held against rotation by a pin 59 secured in, and depending from, the top of the casing 42 and slidable in an opening 60 in a flange 6| on the nut, the nut 58 being thus movable up and. down by rotation of the stem 54 in the appropriate direction. Interposed between the nut 58 and the lower end of the diaphragm 5i is a compression spring 62.

As will be understood, the valve 53 is caused to open and permit steam to enter the radiator responsive to the flow of steam into the chamber 44 at a pressure depending upon the resistance of the valve 53 to upward movement and which resistance is controllable by varying the tension of the spring 62 all to the same end as explained above in connection with the construction shown in Fig. 2, it being possible to entirely close the valve against opening, by forcibly pressing the valve 53 against the valve seat 48.

When high pressure steam, that is, steam at any pressure above atmospheric, is used in the heating system, the spring 62 will be a compression spring so as to aid the atmospheric pressure within the diaphragm and the expansive force of the diaphragm itself in maintaining a balance against the higher steam pressure exerted on the outside of the diaphragm. When low pressure steam, or steam delivered under a partial vacuum, is used in the system the spring 62 maybe a tension spring to maintain the proper balance between the forces exerted on the two sides of the diaphragm 5i or, as shown in the modification as illustrated in Fig. 4, a compression spring 63 may be added Within the steam-chamber 44 and positioned to press upwardly against the lower end of the flexible diaphragm 5|, the spring 62 in such structure being a compression spring, and thus assist the low pressure steam in balancing the higher atmospheric pressure within the diaphragm.

While I have illustrated and described certain particular constructions constituting embodiments of my invention and have illustrated certain particular forms of apparatus for practicing my novel method, I do not wish to be understood as intending to limit it thereto as the constructions shown may be variously modified and altered and the method practiced by other constructions of apparatus without departing from the spirit of my invention, and in this connection it may be stated that my invention, as to certain phases thereof, is not limited to a system for a tall building as explained, but may be used in a system of such low height, either wherein all of the radiators are on one floor or on a plurality of superposed floors, that no appreciable altitude head is encountered in using the system.

What I claim as new, and desire to secure by Letters Patent, is:

l. The method of supplying steam to a plus rality of radiators connected by a system of supply piping to a source of steam supply which consists in increasing the freedom of flow of steam from the supply piping to the radiators as the diflferential between the pressure in the piping and the pressure in the radiators increases, and decreasing the freedom of flow of steam from the supply piping to the radiators as the differential between the pressure in the piping and the pressure in the radiators decreases, and so controlling the said changes in freedom of flow of steam as to cause the amount of steam passing into the radiators to constitute a substantially straight line function of the said differential.

2. The method of supplying steam to a plurality of radiators connected by a system of supply piping to a source of steam supply and disposed at such relative altitudes that an appreciable al-' titude head exists, which consists in increasing the freedom of flow of steam from the supply piping to the radiators as the differential between the pressure in the piping and the pressure in the radiators increases, and decreasing the freedom of flow of steam from the supply piping to the radiators as the differential between the pressure in the piping and the pressure in the radiators decreases to the end of causing the amount of steam passing into the radiators to constitute a substantially straight line function of the said differential, and reducing the freedom of flow to the radiators at the higher altitude as compared to the freedom of flow to the radiators at the lower altitudes by quantities which are suiiicient to compensate for the effect of the altitude head to the end of causing the same relative quantities of steam to be supplied'to the radiators at the higher altitudes as to the radiators at the lower altitudes.

3. In a steam heating system, the combination of a source of steam, a plurality of radiators, a system of piping adapted to conduct the steam to the radiators, said radiators being disposed at such relative altitudes that an appreciable altitude head is produced in the system of piping, re-

rality of radiators of different sizes through re stricted openings of changeable size, which method comprises: a varying the differential of pressure between the radiators and thesource of steam supply; causing the effective area of the openings to increase as the differential increases; and causing the rate of increase to be greater proportionally as the size of the radiators is greater.

5. The method of supplying steam to a plurality of radiators of different sizes through restricted openings of changeable size, which method'comprises: varying the difierential of pres sure between the radiators and the source of steam supply; causing said openingsto be closed 6. The method of supplying steam to a plurality of radiators of different sizes through restricted openings of changeable size, which method comprises: varying the difierential of pressure between the radiators and the source of steam supply in accordance with temperature requirements; causing the effective area of the openings to automatically increase and decrease respectively as the diiferential increases and decreases; and causing the rate of variation in effective area of the openings at the respective radiators to be greater or less proportionally as the size of the radiators is larger or smaller.

FRED I. RAYMOND.

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