US2217087A - Steam heating system - Google Patents

Description

Oct. 8, 1940. M. E. WHITENACK STEAM HEATING SYSTEM Filed May 24, 1957 INVENTOR MIRL E. WHITENACK Patented Oct. 8, 1940 UNITED STATES STEAM HEATING SYSTEM Mirl E. WhitenachNew York, N. Y., assignor to Whitenack Corporation, Chicago, 111., a corporation of Illinois Application May 24, 1937, Serial No. 144,357

11 Claims.

This invention relates to steam heating systems, such, for example, as are used for heating buildings ,and is concerned more particularly with a novel heating system which includes heat radiating units receiving steam from a source of supply, and a control mechanism for regulating the supply of steam to these units. This application is a continuation in part of my edpending applications Serial No. 41,503, filed September 20, 1935,-and Serial No. 118,092, filed December 29, 1936.

In heating systems as now commonly installed, the control mechanism generally is located at a point of heat radiation, or at a point out-of-doors, and is responsive only to changes in conditions at those points. In any ordinary building, it is difficult, if not impossible, to place the control mechanism at a point which will enable it to regulate the temperature satisfactorily throughout the building, and with such systems, certain rooms are likely to be overheated while others are not heated enough. Such systems are wasteful of steam and do not produce the desired result of efiecting close regulation of temperatures.

In the system of the present invention, the control mechanism responds to changes in the system at or near the point of supply of the steam. The control mechanism is made responsive to the sum of the static pressure prevailing in the system and the velocity pressure of steam flowing in the system near the point of admission to the system, and operates automatically to correlate the rate at which steam is supplied to the radiating units with the rate at which it is consumed therein. The control mechanism of the system is extremely prompt and sensitive in its action and acts to vary the amount of steam supplied to correspond closely to changes in demand, with the result that over-running of the supply with incident waste of heat is eliminated and substantially constant temperatures are maintained with great economy.

It is advantageous to operate steam heating systems at subatmospheric pressures to secure the greater heating efliciency that accompanies the use of low steam pressures. heretofore known heating systems at subatmospheric pressures, it has been necessary to provide traps, check valves, and similar devices on the outlet side of the radiating units to prevent the escape and consequent waste of ,uncondensed steam. The present steam heating system preferably is operated at subatmospheric pressures, and owing to the accuracy with which the control mechanism of the system regulates the flow of In operating steam, traps or similar devices on the outlet side of the radiating units may be dispensed with. A

; substantially unobstructed, trupless conduit provides for the withdrawal of c dcnsate from the radiating units.

In operating the heating sgotem of the invention, particularly at a subatmospheric pressure, a partial pressure of air or other non-condensible gas is maintained therein. A partial pressure 0L such a gas in the system reduces the partial pressure due to steam and result in improved heating economies. More important, however, is the fact that the presence of air in the system, especially when the total pressure in the system is below that of the atmosphere, greatly improves the efficiency with which the control mechanism operates. In a system operating at subatmospheric pressures and from which air has been excluded, it is not possible to secure the same close control over steam admission and accompanying heating economies that are obtained when a partial pressure of air is present.

For a better understanding of the invention, reference is made to the accompanying drawing,

in which Fig. 1 is a diagrammatic representation of a steam heating system in accordance with the invention; and

Fig. 2 is a diagrammatic representation of a modified arrangement of apparatus for regulating the pressure in the system.

In the steam heating system shown in the drawing, steam from a source such as a high pressure steammain I0 is admitted to a header or distributing conduit ll through a valve 12. Branch conduits l3 connected to the header or distributing conduit ll conduct steam to radiators I l suitably located in the various rooms of a building to be heated and into the inlet side of which steam is admitted through suitable inlet pipes l5, shown as connected to the bottom of the radiators, as the radiators are built for bottom feed. A return line I6 is connected with the outlet side of the radiators I4 by means of suitable outlet pipes l1 and with means for regulating the pressure in the system. Advantageously the pressure in the system is maintained below at mospheric pressure, and in consequence the prestro'l mechanism comprises a pressure-sensitive element, preferably in the form of an expansible bellows 23; with which a tubular member 2| is connected. The tubular member 2| extends into the interior of the conduitor header II where it is positioned in the path of steam flowing therethi'ough. The lower end of the tubular member 2| is suitably configured to enable it to transmit to the'pressure-sensitive bellows 23 the sum of, the static pressure prevailing in the header and the velocity pressure of steam flowingtherethrough.

A suitable configuration for this purpose is provided by forming the lower end surface of the tubular member 2| at an acute angle to the axis of the member. A substantially lateral opening thereby is provided at the lower end of the tubular element, and this substantially lateral opening is faced substantially into the path of the flowing steam.

A rocker arm 22 mounted to rock about a pivot point 23 ispivotally connected at one ehd to the expansible bellows 23. A spring 24 bears against the other. end of the rocker arm '22. The

spring is mounted in such manner that the force'it exerts on the rocker arm may be adjusted exactly to counterbalance the pressure exerted on the bellows 23 when conditions in the header are at the values it is desired to maintain. If the pressure maintained in the header II is above atmospheric, the spring 24 is under tension, but if, as is preferred, the pressure in the header H is below that of the atmosphere, the spring is under compression. In either case, the force exerted by the spring on the rocker arm 22 is adjusted to counteract the force exerted on the rocker arm by the bellows when desired con-, ditions prevail in the header A contact arm 25 is secured to the rocker arm 23 adJacent the pivoted mounting 23 thereof. 2 Contact points 26 and 21 afe arranged on either side of'the contact arm 25 adjacent its lower end.

The contact points 26 and 21 are spaced from each other and from the contact am so that the contact arm may move back and forth to, make contact with either contact point or to assume a neutral position midway between them.

The above-described control mechanism governs operation of the valve l2 through which steam is admitted to the header through the agency of an electrically operated pilot valve assembly. The pilot' valve assembly comprises a housing 30 divided into a lower compartment 3| and an upper compartment 32 by a partition 33. An opening 34 extending through the partition 33 provides for communication between stem 33 to raise the pilot valve 33 from its seat in the opening 34, and the other motor 33 (referred to hereinafteras the closing motor) actuates the valve stem 33 to move the pilot valve toward its seat in the opening 34. J

A steam tube 33 serves to admit steam under pressure from the main l3 to the lower compartment 3| of the pilot valve assembly. A bleedofl tube 43 provides means of communication between the upper compartment 32 of the pilot valve assembly and the header II to permit the sscaps of steam passing from the lower compartment 3| through the opening 34 into the upper compartment.

The main valve l2, operation of which is controlled by the pilot valve assembly described above, is a diaphragm valve of conventional construction comprising a steam chamber 42 defined by a rigid domed upper wall 43 and a flexible diaphragm 44. The domed upper .wall 43 and the diaphragm 44 are mounted on suitable supporting members 45 connected to the casing of the valve l2. The stem 46 of the main valve I2 is connected to the flexible diaphragm 44 adjacent the center thereof. A tube 41 connects the steam chamber 42 with the lower compartment 3| of the pilot valve assembly.

When the pilot valve 35 is seated in the opening 34, steam under pressure from the main ||I passes through the steam tube 39 to the lower compartment 3| of the pilot valve assembly and thence through the tube 41 to the steam chamber. 42. Substantially the full pressure of the steam in the main l3 thus is exerted on the diaphragm 44, and in consequence the stem 43 of the valve I2 is pressed down with sufllcient force to hold the valve I! closed against the pressure of the steam from the main. If the pilot valve 33 is opened slightly, steam is allowed to escape at a low rate from the lower compartment 3| of the pilot valve assembly into the upper compartment 32 and thence through the bleed-off tube 43 into the header As a result the pressure in the lower compartment 3| and in the steam chamber 42 is diminished somewhat and the main valve is forced openslightly by the pressure of the steam in the main. Further opening of the pilot valve 38 results in further diminution of the pressure in the lower compartment 3| and in the steam chamber 42 and in further opening of the main valve l2. The extent by which the pilot valve 33 is opened thus controls the extent bywhich the main valve I2 is opened and the rate at which steam is admitted from the main III to the header The contact arm 23 and the contact points 24 and 21 are connected through any suitable quickacting electric control 33 with the opening and closing motors 31 and 33 of the pilot valve assembly. A number of suitable electric control circuits are available, but a circuit such as described in my copending application Serial No. 109,559, filed November 6, 1936, is preferred. It will suffice for a complete understanding of the present invention to" point out that the control circuit is such that when the contact arm 25 is moved close to or into contact with one of the contact points 26, the opening motor 31 is energized and the pilot valve 35 is opened, and when the contact arm is moved close to or into contact with the other contact point 21, the closing motor 33 is energized and the pilot valve is closed. v

The control mechanism functions closely to correlate the rate of admission of steam to the system through the main valve l2 with the rate of consumption of steam in the system. Whenever there is a demand for steam "in excess of the rate at which steam is at that moment being admitted, there is a slight decrease in the pressure exerted within the bellows 20, and the bellows collapses sufflciently to nfove the contact arm 25, through the rocker arm 22, toward the contact point 23. The opening motor 31 there- .upon is energized and the pilot valve 33 opens. and the main valve l2, in response to the opening of the pilot valve. also opens and admits steam to the system at an increased rate. on the other hand, if the demand for steam decreases at any moment to below the rate of admission of steam, the pressure within the bellows increases the system is below that of the atmosphere.

the rate of demand for steam.

and the contact arm is moved toward the contact point 21 through which the closing motor 38 is energized. The pilot valve thereupon is closed and the main valve 12 closes correspondingly, thus decreasing the rate of admission of steam to the system.

The control mechanism closely correlates the rate of admission of steam to the system with Since the control mechanism is responsive to the sum of the static pressure in the system and the velocity pressure of steam passing the tubular member 2 I, it prevents the admission of more steam than is necessary to the system, but at all times admits sufllcient steam to meet, within the limits imposed by the capacity of the system, the demand for steam.

In operation of the system, it is preferable to maintain the pressure therein at some constant value below that of the atmosphere, say at some value between about 500 and 38!} millimeters absolute (corresponding to between about 10" and 15" of mercury vacuum), thereby to secure the benefit of heat economies possible with low pressure steam. This pressure may be maintained by a piston type vacuum pump l8 set to maintain the pressure in the radiating units at the chosen value. The piston vacuum pump also serves to withdraw condensate passing from the radiating units through the outlet pipes I1 and the return line I6 and to discharge it through a conduit 5| to waste. t

A modified arrangement of pumps for regulating the pressure in the radiating units is shown in Fig. ,2, in which the return line Hi from the radiating units l4 terminates in a sump 52. A centrifugal type vacuum pump 53 connected with the sump 52 nearthe bottom thereof serves to withdraw condensate collecting in the sump and expel it to waste through a conduit 54. A second centrifugal type vacuum pump 55, advantageously on the same shaft as the pump 53, is connected to the return line I6 at a point above the sump. This second vacuum pump 55, which is set to maintain a proper predetermined pressure in the radiating units, serves to withdraw and expel through a conduit 56 such non-condensible gases as enter the system by leakage or with incoming steam.

In operating the heating system of the invention, particularly at subatmospheric pressures, it

is highly desirable to maintain a partial pressure of air or other non-condensible gas therein. If the total pressure in the system is made up in part by the pressure of a non-condensible gas such as air, the part of the total pressure due to steam is correspondingly reduced; in consequence the presence of air aids in securing'the benefits of economy accompanying the use of low steam pressure. The presence oi air or other non-condensible gas also has'an important bearing on the eificiency with which the control mechanism regulates admission of steam to the system, particularly when the total pressure in In a system operating at a subatmospheric pressure from which air has been excluded, it has been found that the same close control over the admission of steam and the attendant heating economies obtained when air is present in the system are not secured. The exact proportion pressure, and in general amounts to between about 25% and of the total pressure.

A feature of the heating system of the invention is the provision of a substantially unobstructed conduit for the withdrawal of condensate and communicating with the interior of the radiating units and with the vacuum pump regulating the pressure in the system. It'has been customary heretofore to provide traps, check valves, or other obstructions in the outlet pipe through which condensate is removed from the radiating units in order to prevent the escape of uncondensed steam and consequent waste of heat. Traps or the like have been particularly necessary in heating systems operating at sub- .atmospheric pressures because of the suction of of steam is so closely correlated with the demand 35 imposed on the system that traps in the outlet from the radiating units are unnecessary. The outlet pipes l1 and the return line l6 afiord an unobstructed passage of adequate size for the withdrawal of condensate from the radiating units.

In consequence of the precision with which the admission of steam to the heating system of the invention is controlled, provision of hand valves on the inlet pipes I5 to the radiating means I4 is made unnecessary, and no such valves are shown in the drawing. The presence of such valves, however, is not objectionable, and in installations where it may be desirable to shut off some radiating units while operating others,

the provision of hand valves in the inlet pipes l5 may be advantageous.

It is understood that the specific description of the invention given above is by way of example and that modifications can be made in the apparatus without departing from the invention. For example, the particular form of pilot valve described is only one of a number of devices available to the art as the agency through which the valve governing admission of steam to the system is controlled. It is also understood that substantially avoids over-supply of steam and consequent waste of heat while at all times admitting enough'steam to meet the demand im- 7 posed on the system. Elimination of parts such as traps, necessary for successful operation or heretofore known system, greatly reduces-both the first cost and upkeep otthe system of the invention. In actual operation of heating systems according to the invention, substantial economies in operating and maintenance costs, as compared with correspondingcosts of systems supplanted by the system have been achieved.

I claim:

l. A steam heating system comprising a source ofsteam, heat radiating means, aconduit leading from the source to the radiating means, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit, means for varying the admission of steam to the conduit, and means actuated by said pressure-responsive mechanism for actuating the steam-admission varying means to increase the rate of steam admission to the conduit upon a decrease of the static pressureoi the steam in the conduit and also upon a decrease of the velocity pressure of the steam therein, and to decreasethe rate of steam admission upon an increase of the static pressure of-the steam in the conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated with the rate at which it is consumed in the radiating means.

2. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the radiating means, a valve through which steam is admitted from the source to the conduit, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of the steam flowing in the conduit and including a tubular element ex-' tending into the interior of the conduit, and means actuated by said pressure-responsive mechanism to open said valve and increase the rate 01' steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and also upon a decrease of the velocity pressure of the steam therein, and to close said valve to decrease the rate of steam admission upon an in- I crease of the static pressure of the steam in the i conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to theconduit is correlated with the rate at which it is consumed in the radiating means.

3. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the radiating means mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit, means for varying the admission of steam to the conduit, means actuated by said pressure-responsive mechanism for actuating the steam-admission varying means to increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and also ,upon a decrease of the velocity pressure of the steam therein, and to decrease the rate 01 steam admission upon an increase of the static pressure at the steam in theconduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated with the rate at which it is consumed in the radiating means, pressure regulating means for maintaining a predetermined pressure in the radiating means, and a substantially unobstructed of the invention,

with the rate at which it is consumed in the rameans for varying the admission of steam to the ,jaamoa'r conduit communicating wlth'the interior of the sting means on theoutlet side thereof and drawal oi condensate ,irom the radiating 4. A steam heating system comprising a source 5 the pressure regulating means for the witht e sum 01' the static pressure prevailing in the 10 condultand the velocity pressure 01' steam flowing in the conduit and including an element extending into the interior of the conduit, means actuated by said pressure-responsive mechanism for opening said valve to increase the rate of steam admission to the conduit upon a decrease of the static pressure oi the steam in the conduitand also upon a decrease of the velocity-pressure oi the steam therein, and to close said valve and decrease the rate of steam admission upon an in- 8 related with the rate at which it is consumed in the radiating means, pressure-regulating means for maintaining a predetermined pressure inthe radiating means and a substantially unobstructed conduit communicating with the interior oi the radiating means on the outlet side thereofand with the pressure regulating means for the with-' drawal oi condensateirom the radiating means. 5. Asteam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the radiating means, a valve for controlling the admission of steam to the conduit, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit and including a tubular element extending into the conduit having an opening facing substantially into the path oi flow of steam in the conduit, means actuated by said pressure-responsive mech. anism for opening said valve to increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and also upon a decrease of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated diating means, pressure regulating means for maintaining a predetermined pressure in the radiating means, and a substantially unobstructed conduit communicating with the interior of the radiating means on the outlet side thereof and with the pressure regulating means for the withdrawal oi condensate from the radiating means.

6. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the inlet side of the radiating means, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit,

therein, whereby the rate at which steam is idmitted to the conduit is correlated with the rate at which it is consumedin the radiating means, presure regulating means for maintaining a predetermined subatmospheric pressure in the radiating means, and a substantially unobstructed conduit communicating with the interior of the radiating means on the outlet side thereof and with the pressure regulating means for the withdrawal of condensate from the radiating means.

7. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the inlet side of the radiating means, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit and including an element extending into the interior of the conduit, means for varying the admission. of steam to the conduit, means actuated by said pressure-responsive mechanism for actuating the steam admission varying means to increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and also upon a decrease of the velocity pressure of the steam therein, and to decrease the rate of steam admission upon an increase of the static pressure of the steam in the conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated with the rate at which it is consumed in the radiating means, a vacuum pump for maintaining a predetermined subatmospheric pressure in the radiating means, and a substantially unobstructed conduit communicating with the interior of the radiating means on the outlet side thereof and with the vacuum pump for the withdrawal of condensate from the radiating means.

8. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the radiating means, a valve for controlling the admission of steam to the conduit, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit and including a tubular element extending into the conduit and having an opening facing substantially into the path of flow of steam in the conduit, means actuated by said pressure-responsive mechanism to open said valve and increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and, also upon a decrease of the velocity pressure of the steam therein, and to close said valve to decrease the rate of steam admission upon an increase of the static pressure of the steam in the conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated with the rate at which it is consumedin the radiating means, a vacuum pump for maintaining a predetermined subatmospheric pressure in the radiating means, and a substantially unobstructed conduit communicating with the interior of the radiating means on the outlet side thereof and with the vacuum pump for the withdrawal of condensate from the radiating means.

9. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the inlet side of the radiating means, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit, means for varying the admission of steam to the conduit, means actuated by said pressureresponsive mechanism for actuating the steam admission varying means to increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and also upon a decrease of the velocity pressure of the steam therein, and to decrease the rate of steam admission upon an increase of the static pressure of the steam in the conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated with the rate at which it is consumed in the radiating means, means for maintaining a substantially constant pressure in the radiating means, and a substantially unobstructed conduit communicating with the interior of the radiating means on the outlet side thereof for the withdrawal of condensate therefrom.

10. A steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source tothe inlet side of the radiating means, mechanism responsive to the sum of the static pressure prevailing in the conduit and the velocity pressure of steam flowing in the conduit, means for varying the admission of steam to the conduit, means actuated by said pressureresponsive mechanism for actuating the steam admission varying means to increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and also upon a decrease of the velocity pressure of the steam therein, and to decrease the rate of steam admission upon an increase of the static pressure of the steam in the conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is correlated with the rate at which it is consumed in the radiating means, means for maintaining a substantially constant subatmospheric pressure in the radiatin'g means, and a substantially unobstructed conduit communicating with the interior of the radiating means on the outlet side thereof for the withdrawal of condensate therefrom.

11. In the operation of a steam heating system comprising a source of steam, heat radiating means, a conduit leading from the source to the radiating means, and a valve through which steam is admitted from the the source to the conduit, the improvement which comprises opening the valve to increase the rate of steam admission to the conduit upon a decrease of the static pressure of the steam in the conduit and alsoupon a decrease of the velocity pressure of the steam therein, and closing the valve to decrease the rate of steam admission upon an increase oi the static pressure of the steam in the conduit and also upon an increase of the velocity pressure of the steam therein, whereby the rate at which steam is admitted to the conduit is cor-

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