US2515647A

US2515647A - Clear channel steam system

Info

Publication number: US2515647A
Application number: US78605A
Authority: US
Inventors: Orville A Hunt; Tiller Louin
Original assignee: Reconstruction Finance Corp
Current assignee: Reconstruction Finance Corp
Priority date: 1949-02-26
Filing date: 1949-02-26
Publication date: 1950-07-18
Anticipated expiration: 1967-07-18

Description

July 18, 1950 o. A. HUNT ETAL y 2,515,647

- CLEAR CHANNEL STEAM SYSTEM Filedreb.' 26, i949` 2 sheets-sheet 1 .Two 5TA6E 50 HEATER nuo July 18, 1950 o. A. HUNT ETAL CLEAR CHANNEL STEAM SYSTEM 2 Sheets-Sheef Filed Eb. 2e, 1949 lia lut-.r

Patented July l 18, 1950 CLEAR CHANNEL STEAM SYSTEM Orville A. Hunt and Louin Tiller, Chicago, Ill.,

assignors, by mesne assignments, to Reconstruction Finance Corporation, Chicago, Ill., a corporation of the United States Application February 26, 1949, Serial No. 78,605

14 Claims.v

This invention relates to heat-exchange systems employing steam forprocessing materials,

such as steam systems in laundries, paper mills, 'I

and other industries.

The present application is a continuation-inpart of our abandoned application Serial No. 762,628, nled on July 22, 1947, and our abandoned application Serial No. 764,454, led on July 29, 1947. The two prior disclosures, as far as is consistent herewith. are incorporated in the present disclosure by reference.

Other copending applications disclosing the subject matter related hereto are: S. N. 78,842,

nled February 2s, 1949 s. N. 78,843, med February 28, 1949; S. N. 78,604, iiled February 26, 1949; S. N. 80,802, flied February 777,894, filed October 4, 1947.

A steam system of the type here under consideration may be termed a clear channel system, meaning that a clear channel (no traps) exists from the boiler through the equipmentv to the return line. Such a clear channel makes the drop in pressure atv the end of the return line causes an immediate velocity response throughout all the equipment. This fact is important because it makes possible velocity control for the whole system at a single point at the end of the return line.

It is old to create such a pressure dilerential and consequent velocity response solely by opening a valve at the end of the return line, as dis'- closed in Patent 2,366,332 issued to Harrison et al., the released fluid being utilized to preheat and deaerate make-up water for the boiler. But While such a valve arrangement used alone is highly effective and has been commercially successful, nevertheless in some situations it presents certain problems in economy and eiliciency, which problems, We nd, can be solved by adding other ways of promoting velocity and utilizing steam at the return end of the system.

The broad object of the present invention is to provide such solutions by certain actions'at the end of the return line. One such action is the removal of condensate under pressure from the return line above the release valve for direct return to the boiler. This' action of course has a 28, 1940; and s. N."

now-promoting eiect `on' the responsive clear I promoting effect of the release valve and in addition consumes steam in the return line. Other actions include cooling actions taking place in a receiverv at the end of the return line, the release valve being adapted to open in response to such l cooling. These various actions are combined with the action of the release valve invarious waysin various practices of the invention.

An important object of the preferred form of the invention is to achieve a new and novel return system havingthe advantages of an open" system combined for the flrst time with the advantages of a closed system.

When all the returns from the equipment of. a steamlsystem pass through the release valve'at the end of the return line and thus drop tosubstantially atmospheric pressure, as disclosed in the Harrison et al. patent, the return system is termed an open system. The outstanding advantage of an open system is the availability of vmaximum pressure diierential to create ilow through the equipment. This maximum diierential is the full difference between boiler and atmospheric pressure.

One disadvantage of an open system is that bringing all of the returned condensate down to atmospheric pressure causes a substantial portion to flash into steam. It is ditlcult to salvage the B. t. u. s of the ilash steam and usually they are entirelylost to thelatmosphere.

Another disadvantage of an open system is the low temperature of the condensate returned to the boiler, since the maximum possible temperature of condensate at atmospheric pressure is 212 F.

A closed system, on the other hand, in which the condensate is kept under pressure, 4has the advantage of avoiding flashing losses as well as the advantage of returning condensate at high temperature, say around 300 F. in a system operating at p. s. i. g. (pounds per square inch gauge pressure).

As will be explained more fully, the preferred practice of the present invention combines the advantages of open and closed systems by removing the condensate from the return line above the release valve under pressure for direct return to the boiler. eliminated and the condensate reaches the boiler at a high temperature characteristic of 'closed systems. Independently of this action, the release valve is free to set up whatever pressure ddiiierential may be desired just as in open systems.

A further object of the preferred practice of the invention is not only to promote velocity in the system by pressure drop at the end of the return line, but also to deliver the make-up water Thus flash losses are atraen totheboileratahighertemperaturethanpsible in any conventional steam system. This dual obiectisbytransimg mi; fromthereturnlinetothemake-upwaterasthe make-up water travels from the usual feed pump to the boiler. Thus the make-up water causes condensation in the return line to promote new velocityinthesystemandatthesametimeis itselfraisedtoahightemperatureontheorder of300F. Itispossibletoheatthemakc-up watertothishightemperatureandtodosowithout creating any pumping problem because the additional heating occurs on the discharge. side oftbefeedpumpwherethewaterisunderhigh pressure.

These and other objects and advantages of our invention will be apparent from the following detailed description taken with the accompanyins drawings.

In the drawings, which are to be considered as merely illustrative:

Fig. 1 is a front elevation of a typical embodiment of the invention as a self-contained master control unit:

Pig. 2 is a diagram of a representative steam system incorporating the new control unit; and

Fig. 3 is a similar diagram illustrating a modied formof the invention.

Fig. 1 illustrates how the. invention may be embodied in a piece of apparatus thatV may be manufactured as a self-contained unit for installation in steam plants. usually in the boiler room. This form of the unit includes an upright tank or receiver Ill and a housing or casing il associated therewith. 'I'he housing may completely enclose the tank or may, as in the present construction, extend forward from the tank to provide an enclosed space for the numerous elements that make up the control combination. The casing may be oi sheet metal construction with upper and lower slidingdloors I2 that may be opened for access to the interior. The casing includes a panel board I3 on which are various indicating devices that will be described later.

Fig. 1 shows five important pipes connected to the master control unit, the purpose of which pipes will be readily understood from the description below of Fig. 2. 'lhese five pipes are: a pipe i5 for supplying new water to the unit; a pipe i6 connected to the discharge side of the usual boiler feed pump: a pipe l1 which is the boiler feed line for Supplying water to the boiler; the return line I8 of the steam system and., at a lower level, the pipe 2l to the intake side of the boiler/feed pump. If desired. an additional vent pipe 2l may be connected to the vent opening of the tank I0.

Fig. 2 shows atically the principal elements of a steam system including the important parts of the new master control unit. 'I'he parts of the unit itself are shown inside a rectangle 22 indicated by a broken line in Fig. 2. Everything inside this rectangle in Fig. 2 is inside the casing Il of the unit shown in Fig. l.

In the system shown in Fig. 2, steam from a boiler 23 is supplied through a header 25 to a plurality of equipment heat exchangers orsteamusing devices 28. Such devices may be. for example, the various machines in a laundry or the drying equipment used in paper manufacture. plastics, etc. Return pipes 21 from the various pieces of equipment connect with the previously mentioned return line il.

nipple Il of relatively small diameter. It will benotedthatinmchanarraugementthereis a clear channel of open communication from the returnline I8 backthroughthe'varimispiecesof equipment 28 to the boiler so that lowering pressure in the return line II will cause velocity responses in each of the steam-using devices. Thus steam flow through all the equipment may becontrolledfromonepointattheendoftbe return line.

Thereturnline ilmaybeterminallyconnected tothesideoiasteamseparator 3i whichpreferably.butnot .alsoscrveaasaheat exchanger for using the returned condensate to heat new makeup water. The combined heat exchanger and separator Il is shaped and dimensioned to permit the condensate to separate from the steam and, if desired, suitable bailies I2 may be added to facilitate such separation.

The condensate that is separated from the steam gravitates through a Pine ll to the intake side of a condensate pump l5 that is included in the working parts of the master control unit. The pump 36 discharges the condensate upward through a pipe 38. Preferably, the pump operates continuously. A valve 31 is provided in the pipe Il to cut the heat exchanger oi! from the pump if desired.

A pipe 38 conducts iluid from the return line Il into the receiver tank il and for that um is connected to the side of the separator Il. Inside the receiver tank il. the pipe 38 leads to a two-stage combined heater and mixer Il which in turn communicates with a spray head Il. The thermostat control is such that the valve I2 opens in response to decrease in temperature of the thermostat bulb 43 and closes in response to increasing temperature of the bulb. The critical temperature at which the valve opens and closes may be varied by virtue of a manual adjustment 4t on the thermostat valve 42.

The combined heat exchanger and separator Il is, inl effect, an extension of the return line andistoberegardedasapartofthereturnline. Thus the return line ends in the pipe 3l at the thermostatic valve I2. In other words, the combined heat exchanger and separator ll is in the return line Il upstream from the thermostatic valve 42. f

The steam or steam mixed with condensate that flows through the pipe Il and the valve I! enters a central upright passage in the twostage heater 4l and divides, one portion ilowing into an upper jet 41 for the first-stage heating of new water. and the other portion flowing into a lower jet lll for the second-stage heating. The upper Jet AIis directed into a Venturi throat ll and the lower jet Il is directed into a corresponding Venturi throat il, each jet and throat forming a low-pressure space for the introduction of fluid.

New water for the steam system'from the previously mentioned supply pipe ii passes through a oat-controlled valve 52 and through a vent condenser 53 to a pipe il that enters the twostage heater 4I in the low-pressure space between the nrst jet 41 and Venturi throat Il. The resulting mixture flows through a lateral connecting passage 5I into the low-pressure space between the second jet 4l and second Venturi throat Il, where it is joined by the second portion of hot iluid from the pipe 3s. From the two-stage heater the heated water iiows into the spray head Il in heat-exchange relation with the thermo- 75 static bulb Il. The water is not only heated but the tank is of closed construction and the vent 2| is provided with both a vent valve 56 and a relief valve II. The vent valve may be adjusted at a slightly open position to maintain the desired approximate pressure in the tank, and the relief valve 63 may be adjusted to pop oir 'at some higher pressure, say 8 to 10 `pounds per square inch gauge pressure.

Itis contemplated that the spray capacity 'of the spray head Il will be so limited relative to the input of fluid that vthe .pressure in the spray head-will rise above the pressure prevailing in the tank I when the thermostatic valve 42 is open. Under such conditions, the pressure in the spray head may go substantially above the tank pressure. It is further contemplated that the extent to which pressure will rise in the spray head under given conditions may be varied either by varying the 'number of spray openings'or changing the size of the spray openings.

When the heated water is released in finely divided particles from Y.the spray head 4| into the interior of thetank l0. the water particles are shattered by flashing action and" the noncondensible gases are effectively released from the water to escape upwardly through the vent opening 2|. The vent condenser 53 not only reclaims .heat from the escaping -gases but also condenses any vapors that tend to escape with the gases, the recovered condensate dripping to the bottom of the tank.

The feed-water pump 61 may be controlled in a well known manner by means responsive to changes in the water level in the boiler 23 or in some practices of the invention may be manually adjusted to run continuously at approximately the rate' required to keep' the boiler level constant. In either event, the iloat 6| in the master control tank Ill `will-drop periodically to cause new water to be supplied to the system in accord with the boiler demand. Since the boiler demand vfor make-up water varies with the heat load on the system, it is apparent that the master.

control unit is responsive to changes in the heat load on the system.

In the preferred practice of our invention the master control unit is provided with special The tank Ill contains in its lower portion a When the level of this body drops, a suitable float 6| opens the previously mentioned valve 52 by suitable mechanical means including an upwardly extending operating rod 62. If the level of the water body 60 rises-jtoo high, it overflows through an overflow pipe y|53. To prevent the continual release of pressure through the overflow pipe 63, the overflow pipe is provided with a float valve 64 that is normally closed but opens automatically whenever the water level in the tank rises unduly. When desired, the whole vwater content of the tank maybe flushed outby opening a drain valve 66.

The deaerated make-up water, usually at above 212 F.' by'virtueof fthe pressure existing in the tank ID, is taken from the tank through the previously mentioned pipe "26 tothe intake side of the usualboiler feed pump 61 and is discharged by the pump into the previously mentioned pipe I6 that is connected to the top ofthe control unit. The pipe I6 is connected to the inlet end of a heat-exchange cpil 66 in the previously mentioned combined heat exchanger and steam separator 3|. The .outlet end of this coil 68 is joined to the previously mentioned .pipe 36 from' 'the condensate pump 35 to'supply the previously means for introducing pulsations into the steam systcm in a closely controlled manner. An example of such a means is an intermittently operated water valve 10 in Fig. 2. This valve 10. which is in series with the previously described float valve 52 to control the water flow into the vent condenser 53, is of the solenoid type controlled by an electric circuit, the valve being open when the circuit is energized and being closed when the circuit is deenergized.

A pair 'of Wires 1I supply current to an electric timer 12, and wires 13, 14, and 15 complete the circuitwith the solenoid valve 10 in series with a mercury switch 16. The mercury switch 16 is on a rocker arm 11 of the float control mechanism actuated by the oat 6| and closes whenever the float drops in response to demand for new make-up water. Thus the valve 10 is Vintermittently operated during any period in which the float control valve 52 is open. It is apparent that the float control valve 52 may be omitted entirely if desired.

The timer 12 is of a well known type that is manually adjustable to divide a fifteen-second time period into two parts in any desired proportion. For example, the timer may, in repeated l cycles, cause the solenoid of the valve 1|l to be A dial 81 shows the temperature of the feed-l water and a dial 88 shows the pressure ofr the feedwater, both values being taken near theconnection of the boiler feed line I1 withthe master control unit. The dial 90 indicates the deaeration temperature and the dial 9| indicates the deaeration pressure, both values being taken near the thermostatic bulb 43 where the fluid under pressure flows into the spray head 4 l Dial 92 shows the return line pressure near the point at which the return line I8 connects with the combined heat exchanger and separator 3|. A dial 93 shows the pressure of the make-up water supply taken near the connection of the water supply pipe I5 with the unit. A signal lamp 95 is responsive to the mercury switch 16 to indicatev theperiods in which the system is taking in new water and a second signal lamp 96 responds to energization of the solenoid valve10 to indicate the pulsating action created bythe make-up water. The previously mentioned timer e 7 12 is placed on the Justment as desired. A gauge glass 01 indicates thewaterlevel inthe master controltankanda switch Il on the panel controls energization of the condensate motor 2S.

Operation 'I'he manner in which the steam system oppanelboard for manual aderates and is controlled by the described unit ries the condensate out of the steam chests along with noncondensible gases. The drop in pressure at the restrictions 28 causes some of the condensate to flash into steam thereby slightly increasing the steam content of the iluid mixture that reaches the combined heatexchanger and separator 2l.

In a steam system having approximately 100 pounds per square inch gauge pressure in the steam header 2l. the setting of the thermostatic valve 42 may be, for example, somewhat above 230 F. In any event, the temperature setting of the thermostatic valve will be above the normal temperature prevailing inside the tank I but below the normal temperature of steam in the rethermostatic valve. acting independentlyo! the' make-up water supply. opens peribdically in an 4automatiemanner tomaintainadesiredminimum average iiow velocity in the system.

Whenever new make-up water is acquired the float lowerstoopenthewatervalve l2and at the same time the mercury switch Il tilts to closeacircuitthroughthesolenoidvalve'lland timer 12. Aslongastheiioatll isinitslower position, the solenoid valve Il opens intermittentl'y to release pulses of make-up water for flow through the vent condenser l2 and pipe Il into the two-stage heater-mixer.

Each pulse of water causes the thermostatic bulb 43 to be cooled thereby to open the thermostaticvalve42 iorthereleaseoi'steamrrom the system.A In the usual method ot'operation. themixtureofsteamandwateristoolowln `temperature to cause the thermostatic valve 42 toclosesolongascoldwatercontinuestoiiow .through the solenoid valve 1l. As soon. however.

as a pulse of water from the solenoid valve 'Il terminates, the steam or steam and condensate from the thermostatic valve 42 raises the temperature in 'the spray head to cause the thermostatic valve to close. A

It is apparent that the described thermostatic' into the receiver tank I0 substantially concurturnline Il. Hthetank Il isat4 1'0'6 pounds gauge pressure. the temperature therein -will be in the range 224-230 F. g I

, Usually the temperature setting of the thermostatic valve 42 is higher than the steam temperature corresponding to the normal pressure in the receiver tank II. The thermostatic bulb 43, however, is in the spray head 4l or at least rent with the admission of make-up water causes the make-up water to be heated to a temperature substantially above 212 F. and places the heated make-up water under considerable pressure in the spray head 4I.-v When this high-temperature high-pressure 'water is released from the spray head.4l into the lower pressure of the receiver tank I0, a lsubstantial portion o! the heated water ilashesintosteaminaninstantaneousmanner. This flashing action causes each spray droplet to be shattered with consequent release and separation of the noncondensible gases. The de- In various practices of the invention, the thermostatic valve 42 may completely close or nearly close in response to rising temperature and may be either a quick-acting valve or a stage-acting valve.

` Ii' a snap-acting thermostatic valve 42 is employed, it will, in the absence of ilow of make-up water, operate inherently infan intermittent or pulsating manner. 'Ihus when the thermostatic aerated water drops to the bottom of the tank I0 while the released noncondensible gases iiow upward to the vent 2|. The vent condenser Il not only condenses any steam that may tend to escape but also reclaims heat from the separated gases.

If the thermostatic valve 42' is of the stageoperating type, as distinguished i'rom the abovedescribed snap-acting type, it will continuously seek an equilibrium position in accordance with its temperature setting. -In the absence of the flow of make-up water. the equilibrium-position of the valve will admit iluid from the return line of the system into the receiver tank Il at a rate to maintain a pressure and consequent temperature in the spray head 4l corresponding to the Atemperature setting ot the thermostatic valve.

When make-up water is demanded, the eilect of each'pulse of make-up water released by the solenoid valve 1li is to cause the valve to open wider. 'I'hus with a stage-operating ,valve dow tendsto be constant at some minimum level in the absence ci' make-up'water ilow, and when make-up water ilows the thermostatic valve will operateinapulsatingmannerbyvirtueofthe water pulses released by the solenoid valve 1l.

A special advantage of this adjustable arrangement for breaking the make-up water flow into pulses is that the rate at which new water is supplied and deaerated may bemore or less independent of the action of the boiler feed pump 61. For example, the boiler feed pump 61 may, in a. given installation, operate for five minutes and then remain idle for 20 minutes. During the ve minutes of pump operation the water 'level of the reserve body of make-up water 60 in the tank I0 will drop several inches. During the following 20 minutes in which the pump is idle, the solenoid valve 10 will release pulses of water into the receiver to restore the water level.

The timer 12 may, if desired, be so adjusted that the time taken for the water level to be restored is approximately 20 minutes. Thus the new water is sent through the deaeration process gradually, notwithstanding the periodic abrupt drops in the water level inside the tank I0.

Since the master control responds to demand for new water at the boiler end of the system and in doing so speeds up velocity at the return end of the system, the unit may be said to tie the two ends of the system together functionally. The result is a closed chain of causes in which the demand of the boiler for a pound of water to replace a pound of steam consumed in the system causes enough velocity to be created to sweep out the resulting condensate from the steam chests in the system.

Each time the valve 42 opens it causes two things to happen. I t causes a pressurelpulsation or slight pressure drop in every steamchest in the system, and it causes velocity ln the whole system to speed up. In other words, each opening movement of the valve 42 causes a pressure pulsation in each piece of equipment and at the same time causes a strong surge offlow from the equipment through the return line of the system. The pressure pulsations in effect attack the noncondensible gas films in the steam chests because each pressure drop causes a portion of every particle of water in the steam chests to flash into steam in an instantaneous manner. There are countless particles in and near the gas films, and at 100 pounds pressure per square inch the condensate that flashes into steam increases in volume over 240 times. As a result, each particle of water becomes an explosive center of turbulence to disrupt the gas films and to promote heat transfer to the material in process.

The gases torn away from the gas lms are quickly picked up by the velocity surges and swept into and through the return line of the system. The velocity surges also sweep condensate out of the steam chests continuously and keep the condensate films exceedingly thin.

Normally, the receiver tank I has therein a cloud of steam created by the described deaeration process, which steam accounts for the pressure in the receiver tank being normally a few pounds above atmospheric pressure. When new water released by the solenoid valve flows into and through the vent condenser 53 inside the receiver tank l0, the resultant condensing action on the cloud of steam in the tank lowers the pressure and temperature in the tank. This action has a'certain effect on the thermostatic bulb 43 since a pressure drop inside the tank, tends to create a pressure drop inside the spray head 4|. Thus the flow of water into the vent condenser 53 considered apart from all other concurrent actions tends to cool the thermostatic bulb 43 for opening action by the thermostatic valve 42.

- 10 Only water of exceptionally high temperature is fed to the boiler 23 because the condensate returned through the pump 35 is held at high pressure and because all new water added to the system is first preheated at low pressure, then heated at high pressure, and finally intermixed with condensate. The first stage of heating the new avater is in the vent condenser 53; the next two stages are in the two-stage heater 40; and the fourth stage with the Water under pressure from the pump 81 is accomplished by the cons B8-in the combined heat exchanger and separator 3|. In a system using steam at about pounds gauge pressure, final mixture of feed water reaching the boiler is above 300 F. and often around 330 F.

The arrangement shown in Fig. 2, however, has several provisions for promoting flow in cooperation with the themostatic release valve 42. the first place, the cooling effect of the vent condenser 53 reduces the pressure and temperature inside the tank with consequent cooling action on the thermostatic bulb 43. In the second place, the continuous removal of condensate by the pump 35 from the lower end of the separator 3| creates flow in the return line I8. In the third place, the exchange of heat for condensing of steam in the separator 3| by the cooling effect of the water coil 63 and/or the cooling effect of water introduced by the spray head |04 serves to promote flow by contraction of the fluid mixture in the end of the return line.

All of these factors working together create yand maintain whatever now velocity is desired in any particular steam system. But it is not necessary in every instance to employ all of the abovementioned actions to supplement the action of the release valve. 'I'hus the required flow velocity for a steam system may be had by combining the action of the vent condenser 53 alone with the action of the thermostatic valve, or by combining the direct return ofcondensate alone with the action of the thermostatic valve, or by combining the condensing action in the return line alone with the action of the thermostatic valve,4

or by combining all or any two of these three supplementary actions with the action of the thermostatic valve.

A special advantage of pumping feed water through the heat exchanger coil 68 is that the water in the coil 68 is under high pressure and is therefore capable of absorbing more B. t. u.s from the return line than would otherwise be possible. This arrangement which raises the steam-condensing capacity of a given quantity of the make-up water to the maximum is especially valuable in a steam system having a. relatively low make-up water demand.

Although opening the thermostatic valve 42 to create velocity may tend to lower the pressure of the condensate delivered to the condensate pump 35, the valve opens only intermittently so that such tendency to drop pressure can occur only intermittently.

Tunzn'g the unit to suit a particular steam system A feature of the invention is that it incorporates a number of elements that may be changed or adjusted to cause the master control unit to match precisely the requirements of any steam system Within a very wide range. As a result, the control unit is extremely flexible and is not only readily adaptable to the requirements of any particular system but is also adaptable to changes in a steam system such as the addition of new heating equipment.

Any of the following adjustments may be made to vary the operation and control characteristics of the unit:

1. The temperature adjustment 45 -of the thermostatic valve 42 may be varied.

2. The rate of 'supply of the new water may be varied to change the cooling effect of the new water on the thermostatic bulb 43. For example, the float valve 52 may be restricted or limited in its opening action to any degree desired.

3. The closing action of the thermostatic valve 42 as well as the opening action may be limited to any degree desired.

4. The discharge capacity of the spray head v 4| may be varied to regulate the manner and degree of pressure rise in the spray head.

5. The prevailing pressure in the master control tank may be raised or lowered.

6. The proportion of make-up water diverted to the spray head |04 in the separator 3| may be varied by the manipulation of the valves |05 and |06.

.7. The dura-tion of the water pulses controlled bythe solenoid valve may be varied by adjustment of the timer.

If desired, the master control unit may be operated with the valve 31 closed and the condensate pump 35 de-energized. In that event, all

of the returns from the system will be discharged through the thermostatic release valve 42 into the receiver tank I0. To make sure that the valve I I0 releases the volume of fluid required for this kind of operation, it may be necressary to change the temperature adjustment 45 oi' the thermostatic valve to a higher setting. In some situations it maybe decided to make this kind of operation standard practice. In any event, the method of operation can be used temporarily any time it is necessary to service or repair the pump 35.

Description of Fig. 3

lar m the previously described timer 12.

The timer ||I is energized by a pair of leads switch 10 that closes ywhen the oat 6| drops. A pair of wires IIB lead from the timer I to the solenoid valve 10 that controls the introduction of new water, and 'a second pair of,wires I I1 lead from thetimer to the 'solenoid release tion may be readily understood. The adjustment of the timer determines the duration of the short periods in which new water is introduced into the master control unit and causes steam to be released by the valve ||0 in synchronization with the water ow. As long as the float 6| is in its lower position, the relay |20 keeps the second timer |I2 de-energized. Whenever the float rises to its upper position, however, the relay |20 is de-energized and automatically closes the circuit to energize the second timer H2, whereupon the second timer intermittently opens the release valve H0'.

It is apparent that the timer may be readily adjusted in accord with the specific make-up water requirement of a particular steam system so as to spread out the ow of new water to whatever extent may' be desired. On the other hand, the timer ||2 may be adjusted to determine the release of uid from the return line of the system when make-up Water is not required. This second timer ||2 will, of course, be adjusted to maintain whatever minimum velocity in the system is needed between the periods of make-up water demand.

Our description in detail of preferred practices of the invention for the purposes of disclosure and to illustrate the principles involved will suggest to those skilled in the art various changes and substitutions under our basic concepts. We reserve the right to all such departures from our disclosure that fall within the scope of our appended claims.

We claim as our invention:

1. In a steam system having a boiler, at least one steam-using device connected to the boiler, and a return line connecting the steam-using device to the boiler and closed to the outer atmosphere, said device and return line forming a clear channel from said boiler for dow-promoting pressure communication through the system, the combination therewith of: 'a condensate pump in the return line for returning condensate to said boiler under pressure, said pump having its intake port in direct communication with said return line to promote flow of steam through the steam-using device, and a valve to release fluids from said return line into a region of substantially lower pressure than the return line to set up a pressure differential across the system for additional promotion of ow in the steam system.

.HI and |I5 under the .control of the mercury valve H0. Whenever the iioat 6I drops in re..-

sponse to the boilers requirement for make-up water, the timer |I| is automatically energized by the mercury switch 16 to open the two solenoid 4valves 10 and |||l intermittently in unison.

The second timer ||2 is also energized by the leads H3 and ||5 but is under the control of a relay |20 that is in parallel with the timer to be energized simultaneously with thevtimer I This second timer ||2 is connected by a pair of wires |2| to the previously mentioned wires' ||1 that control the solenoid release valve H0'.

The operation of this modied form of inven- 2. A steam system as set forth in claim l, which includes means to open and close said release valve intermittently to create pressure pulsations in said system.

3. In a steam system having a boiler, at least .one steam-using device connected to the boiler,

and a return line connecting the steam-using device to the boiler and closed to the outer atmosphere, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the come bination therewith of: a valve to release iluid from said return line into a region of substantially lower pressure than the return line to set up a pressure diiferential across the system for promoting ilow of steam through the steam-using device, and means operatively connected with the return line to bring cooling iluid into heat exchange relation with the contents of said return vline for causing condensation of steam therein to create a further pressure differential for further promotion of flow in the system.

4. A steam system as set forth in claim 3, which includes means to open and close said release valve intermittently to cause pulsations in the system.

5. In a steam system having a boiler, at least one steam-using device connected to the boiler, and a return line connecting the steam-using device to the boiler and closed to the outer atmosphere, said device and return line forming a clear channel from said boiler for flow-promoting presfrom said boiler for flow-promoting pressure communication through the system, the combination therewith of: a condensate pump for returning condensate to said boiler under pressure, said pump having its intake port in coml munication with said return line to promote iiow sure communication through .the system, the

combination therewith of: means to bring cooling fluid into heat-exchange relation with the contents of said return line for causing condensation of steam therein to set up a pressure differential across the system for promotion of iiow of steam through the steam-using device, a condensate pump in the return line for returning condensate to said boiler, said condensate pump having its intake port in direct communication with said return line to remove condensate therefrom for further promotion of iiow in the system, and a valve to release fluid from said return line into a region of substantially lower pressure than the return line to set up a further pressure diierential across the system for still further promotion of iiow in the steam system.

6. A steam system as set forth in claim 5. which includes means to open and close said valve intermittently to create pulsations in the system.

7. In a steam system having a boiler, at least one steam-using device connected to the boiler, and a return line connecting the steam-using device to the boiler and closed to the outer atmosphere, said device and return line forming a clear channel from said boiler for dow-promoting pressure communication through the system, the combination therewith of: a separator in said return line for separating steam and condensate, a condensate pump in the return line for returning condensate to said boiler under pressure, said pump having its intake port directly connected to said separator to promote flow in the system, and a valve connected with said separator to release steam therefrom into a region of substanin the system, a rst electrically controlled valve to release fiuids from said return line into a, region of substantially lower pressure than the return line to set up a pressure diiferential'across the system for additional promotion of iiow in the steam system, a second electrically controlled valve to release make-up water for mixture with the fluid released by said first valve, a, ilrst timer to operate said two valves together intermittently,

a second timer to operate said second valve interi mittently, and means to energize the iirst timer tially lower pressure than the return line to set up a pressure diiierential across the system for additional promotion of flow in the steam system.

8. In a steam system having a boiler, at least one steam-using device connected to the boiler, and a return'line connecting the steam-using device to the boiler and closed to the outer atmosphere, said device and return line forming a clear channel from said boiler for flow-promoting pressure communication through the system, the combination therewith of: means operatively connected with the return line to bring cooling iiuid into heat exchange relation with the contents of said return line for causing condensation of steam therein to set up a pressure diierential across the system for promotion of flow in the system, a separator in said return line for separating steam and condensate, a condensate pump in they return line for returning condensate to said boiler, said condensate pump having its intake port in direct communication with said separator to remove condensate therefrom for further promotion of flow in the system, and a valve to release uid from said separator into a region of substantially lower pressure than the return line to set up a further pressure differential across the system for still further promotion of ow in the steam system.

9. In a steam system having a boiler, at least `'one steam-using device, and a return line, said #device and return line forming a clear channel when the steam system requires make-up water and alternately to energize the second timer when make-up water is received.

10. In a, steam system having a boiler, at least one steam-using device) and a return line, said device and return line forming a clear channel from said boiler for ow-promoting pressure communication through the system, the combination therewith of: a separator in said return line, a heat-exchange passage in said separator to bring cooling iiuid into heat-exchange relation with the contents thereof for causing condensation ol? steam therein to set up a pressure differential across the system for promotion of iiow in the system, a condensate pump for returning condensate to said boiler, said condensate pump having its intake port in a communication with said separator to remove condensate therefrom for further promotion of flow in the system, and a valve to release iiuid from said separator into a region of substantially lower pressure than the return line to set up a further pressure differential across the system for still further promotion of flow in the steam system.

11. A steam system as set forth in claim 10, which includes means to open and close said valve intermittently to create pulsations in the system. i

12. In a steam system having a boiler, at least one steam-using device, and a return line, said device and return line forming a clear channel from said boiler for How-promoting pressure communication through the system, the.combi nation therewith of: a valve to release fluid from said return line into a region of substantially lower pressure than the return line to set up a pressure differential across the system for promoting iiow in the steam system, means to use said released iiuid to preheat make-up Water, and means to bring the preheated water into heatexchange relation with the contents of said return line for causing condensation of steam therein to create a further pressure differential for further promotion of iiow in the system.

13. In a steam system having a boiler, at least one steam-using device, and a return line, said device and return line forming a clear channel from saidv boiler for' now-promoting pressure communication through the system, the ycombination therewith of: means to bring make-up water intoheat-exchange relation with the contents of said return line for causing condensation of steam therein to create a further pressure diierential for further promotion of flow in the system, and means to raise the pressure of said make-up waterto increase the capacity of the I www therewith of: 'o valve to release lluid from ssidreturnlineinwaregionofsubstantlally lowerpressurethsnthereturnlinetnsetupaprelre dierential across the system for promotinzowinthesteamsystemmeanstousesaid released iiuid to greheat make-up water, means to nise'the pressure of said. preheated make-up water to increase its-capacity for absorbing heat without vsporins. and meansto bring the preheated and pressurized water into heatexchange relation with the contents of said return line for.

causing eondenssto of steam therein to creste.

sfurther pressure diilerentisl for further promotlonoffiowinthesystem.

DEVILLE A. HUNT. IUIN TILLER.'

nmnNcEs 'cmm The following references are of record in Athe l0 file of this potent:

UNITED STATES PATENTS Number 2,001,344y 15 2,353,486 2,366,332

Harrisonjet al. Jan. 2, 1945