US2515651A - Steam heating system - Google Patents

Description

July 18, 1950 E. P. HARRISON E'rAL- 2,515,651

STEAM HEATING SYSTEM Filed Oct. 4, 1947 6 Sheets-Sheet 1 MASTER CONTROL PUMP u f r flu/P02101 5. m 662mm Paw/Maeda,

July 18, 1950 E. P. HARRISON Erm. 2,515,651

STEAM HEATING SYSTEM Filed oct. 4, 1947 e sheets-sheet 2 rwfj 0 n 8f 66 a7 m VALVE l 38 f@ :l '$6 36 l lr l lr p l\ fr '-32 37 vf 7 66 l .L i g i l 0 49 #46 6 48 I J 4? July 18, 1950 E. P. HARRISON Erm. 2,515,651

STEAM HEATING SYSTEM July 18, 1950 P. HARRISON ETAL 2,515,651

STEAM HEATING SYSTEM Filed Oct. 4, 1947 6 Sheets-Sheet 4 MASTER CONTROL TO .BOILER 'gfx-Sgam To wA-rz-:R TRMTMEN-r FROM WATER TREATMENT .BOILER flu/@1M 'nmAWMM/mzm @A4/fa a. W24/nf* www 5.

July 18 1950 E. P. HARRISON Erm. 2,515,651

STEAM HEATING SYSTEM Filed Oct. 4, 1947 6 Sheets-Sheet 5 T I S Q O B0 LER ffm/@wrs wam MKM/am, @A4/We @.dm V- y- 7 z E t l July 18, 1950 E. P. l-lAn'msoN rs1-AL 2,515,551

STEAM HEATING SYSTEM Filed Oct. 4, 1947 6 Sheets-Sheet 6 CON DE NSATE PUMP Patented July is, 195o STEAM HEATING SYSTEM Elmer Paul Harrison, Chicago, lll., Orville A. Hunt, Oklahoma City, Okla., and Louin Tiller, Chicago, lll., assignors, by 4direct and mesne assignments, to Reconstruction Finance Corporation, Chicago, Ill., acorporation of the United States Application october 4, 1947, serial No. 117.894

1s claims. y(01.237-9) This invention relates to heat exchange systems employing steam for processing materials, auch as steam systems in laundries, paper mills., and other industries.

The invention pertains particularly to irnprovements in steam systems such as described in the Harrison and Hunt Patent No. 2,366,332, the copending application of Harrison and Hunt Serial No. 581,586, led March 8, 1945, entitled Heat Exchanger System. and the abandoned application of 'Iiller and Hunt Serial No. 762.628, filed July 22, 1947, entitled Steam System. The present application is a continuation in part cf the abandoned application of Harrison et al., Serial No. 701, 252, iiled October 4, 1946, entitled Steam Heating System." The four mentioned disclosures are hereby incorporated in the present disclosure by reference. insofar as consistent herewith.

Other copending applications disclosing the subject matter related hereto are: S. N. 78,605, led February 26, 1949; S. N. 78,843, filed February 28, 1949; S. N. 78,842, filed February 28, 1949; S. N. 78,604, led February 26, 1949; and S. N. 80,802, flledFebruary 28, 1949.

A steam system of the type here involved is characterized by open channels for continuous flow from the steam supply through the equipment steam chests to the end of a return line in combination with thermostat means to release fluid from the return line into a region of lower pressure in a controlled manner to maintain a desired velocity level or average throughout the system. In the preferred practices of the invention a master control for regulating such release from the return line includes a receiver for fluid returned from the steam system and/or new water for the system'.

The volume or rate of fluid release from the return side of the steam system is sufficient to minimize condensate in the system and to maintain a high rate of heat transfer to the material being heated. The master control is adjustable and the optimum rate of release for which the master control is set varies among` installations. The act of adjusting'the master control with respect to the rate of release from the return side of the system is aptly referred to as tuning the master control unit. The inherent range of adjustment should be extensive to m'ake the mas- 2 ter control readily adjustable to different steam systems and different operating conditions.

One of the general objects of the present invention is to provide an augmented tuning range for the master control and to provide means and methods for applying the principles of the invention to a wide range of steam systems.

In some practices of the invention this general object is attained by the introduction of a modifying factor in the functioning of themaster control. One example isthe introduction of a cooling fluid to modify the action of a thermostat-controlled valve that controls the release of fluid from the return side of the steam system. Another example of introducing a modifying factor is the use of a heat exchanger to cause condensation of vapor in the return side of the system upstream from' the thermostat valve so that velocity of flow through the steam system is promoted not only by the action of the thermostat valve but also by the action of the heat exchanger.

In other practices of the invention a modifying factor and a new combination of functions is provided by regulating the rate at which uid is released from the receiver. The pressure in the receiver is determined, on the one hand, by the rate at which fluid is released into the receiver from the return side of the system and, on the other hand, by the rate at which iluid is released from the receiver. The thermostat for controlling release into the receiver responds to temperature changes in the receiver, which temperature changes, of course, vary with pressure changes. The temperature setting of such a thermostat is one tuning factor and the rate at which fluid is released from the receiver is a modifying factor which, taken with the first factor, affords a wide range of adjustment.

The fluids released from the receiver may be utilized in any desirable manner. For example, steam and/or condensate from the receiver may be used for preheating and deaerating make-up water. In this regard one embodiment of the invention comprises a novel arrangement of a receiver and a remote deaerating feed water heater. x

A further object of the invention in certain of its practices is to favor the creation of pressure changes, velocity surges and pulsations in the system for the sake of certain beneficial results.

Other objects and advantages of the invention will be apparent in the description to follow, taken with the accompanying drawings.

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

Fig. 1 is a diagrammatic view illustrating one embodiment of the invention;

Fig. 2 is a diagrammatic view showing certain details of the master control in Fig. 1;

Fig. 3 is a fragmentary sectional view showing how an orifice member may be employed in the system;

Fig. 4 is a fragmentary diagrammatic view indicating how air instead of water may be used for the cooling fluid;

Fig. 5 is a fragmentary diagrammatic view of a master control employed in a modified form of the invention;

Fig. 6 is a diagrammatic view representing a steam system incorporating the master control of Fig. 5.

Fig. 7 is a fragmentary view similar to Fig. l showing how the arrangement shown in Fig. 1 may be modified;

Y Fig. 8 is a diagrammatic view of another embodiment of the invention;

Fig. 9 is a diagrammatic view of an embodiment of the invention combining a receiver under pressure with a remote cooperating deaerator;

Fig. 10 is a diagrammatic view of an embodiment of the invention using a jet-compressor; and

Fig. 11 is a diagrammatic cross-section of the jet-compressor.

Fig. 1 shows, by way of example, the invention incorporated in paper drying machinery having a plurality of heat exchangers in the form of driers or cylinders I8. The web of paper to be dried moves in the direction indicated by the arrow II and makes successive contact with the rotating cylinders I6.

A boiler I2, or equivalent steam source, delivers steam through a suitable supply line I3 to a supply header I4, and the various cylinders I0 are connected in parallel to the supply header by suitable feed pipes I5. Each of the feed pipes I5 communicates with the corresponding cylinder Il through the trunnion of the cylinder, as indicated in Fig. 2, and condensate is discharged from the cylinder through a, suitable discharge pipe I1 that extends through the same trunnion of the cylinder and through a portion ofthe feed pipe. The discharge pipe I1 of each cylinder leads to a suitable return header I8.

In accord with a common practice it is contemplated that the outflow from each of the cylinders Il will be restricted relative to the inflow to the cylinder for the purpose of proper steam distribution among the cylinders and for maintenance of the desired pressure differential between the supply -header I4 and the return header I8. In the described arrangement the discharge pipe I1 from each drying cylinder I0 is suiliciently smaller in diameter than the corresponding supply pipe I5 to provide the desired restricting eect, but in some practices of the invention the restriction in the outflow from each drying cylinder may be provided, either by a valve or by an orifice member. Fig. 3, for example, shows an oriilcemember 28 in a discharge pipe 2|, the orifice member being housed in a suitable fitting, generally designated 22.

Preferably the heat exchangers or drying cylinders Il are grouped into subdivisions or banks of cylinders. Such grouping may be accomplished by. in effect, providing separate return headers for each subdivision. In the construction shown in Fig. 1, instead oi providing structurally separate return headers for the various banks we employ the single return header I8 but incorporated therein suitable valves whereby the header may be divided into functionally separate sections. Thus the twenty-four drying cylinders I0 shown in Fig. 1 may be grouped into four subdivisions or banks of six cylinders each by closing three valves designated 25, 26 and 21.

A feature of the arrangement shown in Fig. 1 is adjustability with respect to the grouping of the drying cylinders I8 into subdivisions or banks. Thus,'by opening valves 25, 26 and 21 and closing valves 28, 29 and 30, the drying cylinders will be regrouped into banks comprising four, five, seven and eight cylinders, respectively. In such regrouping it will be noted that there is a relatively small number 'of cylinders in the first bank reached by the traveling paper, which cylinders are known as wet rolls, and a relatively large number of cylinders or dry rolls in the last bank. Since more steam is condensed on the wet end of the series than on the dry end, this grouping tends to equalize the amount of condensate that must be carried away from each of the return header sections.

The four sections of the return header I8 are connected with a master control, generally designated 3i, by means of four individual return lines 32, respectively. As shown in Figs. 1 and 2, the master control 3l includes a receiver tank 36, and four control or release valves 31 in the four return lines 32, respectively, operated by four corresponding thermostats 38. The receiver tank may be at substantially atmospheric pressure, or at some pressure above atmospheric. In this instance it is assumed that a vent line 40 for the receiver tank is suitably adapted to maintain a moderate pressure in the tank.

Each of the return lines 32 may be provided with a suitable check valve 83 and a manually operable valve 84. Preferably each of the return lines 32 is also provided with a suitable strainer. Fig. 2 shows a well-known Y-strainer 85 which may be flushed whenever desired by opening a valve 86 in a pipe 81. As indicated in Fig. 2, the flushing action may be directed into the receiver 36 or may be directed through a branch pipe 88 to waste.

In the particular arrangement shown in Fig. 1, condensate discharged into the receiver tank 36 by the four return pipes 32 is conveyed from the tank by a pipe 4I to a pump 42, and is forced by the pump through a pipe 43 to a suitable feed water tank 45. The pump 42 operates continuously, but whenever the liquid level in the receiver tank 36 drops to a predetermined minimum level a cut-off valve 46 in the pipe 43 is closed automatically by a float controlled means 41, whereupon the condensate discharged from the pump 42 is recycled through the receiver by virtue of a by-pass line 48 equipped with a. relief valve 48. The relief valve 49 is spring loaded to maintain a closed position, but opens in response to the pressure rise in the discharged condensate that results from closing of the cutoff valve 46.

New water to make up for losses in the system is delivered to the feed water tank 45 through a supply pipe 50, the supply pipe being equipped with a iloat controlled valve 52 that opens in response to lowering of the water level in the iced water tank. From the feed water tank a suitable boiler feed pump Il replenishes the boiler i2 through a feed line 5I in response to the usual automatic means (not shown) controlled by the water level in the boiler.

The specific construction of the master control 3I may be understood by referring to Fig. 2. It will be noted that the bulb 55 of the thermostat 33 that contains the usual volatile fluid for operating the corresponding release valve 31 is in ay pipe 51 on the discharge side of the 'release valve, and that the pipe 51 is larger in diameter than the return line -on the inlet side of the release valve, so that the released fluid has space in which to expand. The relationship between the thermostat and the valve is such that the valve closes, or at least partially closes, in response to increasing temperature, and opens, or at least opens to a greater degree, in response to decreasing temperature, the relationship being adjustable to cause the valve to open and close at selected temperatures. Thus the release will be in a pulsating manner, the release being by pulsating continuous flow if the valve merely iluctuates between two open positions and being by pulsating intermittent ilow if the valve actually closes.

The pipe 51, housing the thermostat bulb, communicates with one or more downwardly directed spray heads 58, and it is important for the purpose of the invention that the small discharge apertures of the spray heads have suiliciently low flow capacity to restrict the outflow from the pipe 51 relative to the inflow. In other words, the discharge capacity of the release valve 31 is so much greater than the discharge capacity of the spray heads that prolong discharge from the release valve into the pipe 51 will cause a pressure rise in the pipe. Because of this action the pipe 51, in combination with the spray head 58, may b e aptly termed a pressure accumulation chamber.

The critical temperature ci' each thermostat 38, or the temperature at which the thermostat is adjusted to cause opening action or closing action of the corresponding release valve 31, is above the normal temperature of the receiver tank 36 and below the temperature prevailing in the corresponding return line on the inlet side of the release valve 31, so that opening action of the release valve occurs automatically as the temperature in the accumulation chamber drops toward the normal temperature and closing action occurs automatically as the fluid released into the pressure accumulation chamber raises the temperature therein toward the temperature level in the corresponding return line that supplies the valve. By virtue of this arrangement the release valve causes pulsating flow in the system.

By way of example let it be assumed that the normal pressure of the condensate and steam on the inlet side of the release valve 31 is approximately thirty-two pounds, with the condensate at the corresponding temperature of 277 F.; that the pressure in the reservoir tank 36 is on the order of six pounds maximum, with a corresponding temperature of 230 F.; and that the thermostat setting is 255 F. As heretofore stated, prior to opening action of the release valve 31 the pressure and temperature in the pressure accumulation chamber approximate the pressure and temperature in the receiver tank. Upon opening action of the release valve 31, however, condensate, or a mixture of condensate and steam, is introduced into the pressure accumulation chamber in large amount and with drop in pressure. The drop in pressure, of course. causes at least a portion of the condensate to flash into steam. As a result of the fluid introduction and of vaporization of the introduced fluid on one hand, and on the other hand the restriction of outilow by the spray apertures, the pressure in the pressure accumulation chamber rises with corresponding rise in temperature. When the temperature reaches approximately 255 or more. depending upon the lag in the operation of the thermostat, the release valve 31 is automatically operated in a closing direction, and immediately the pressure and temperature in the pressure accumulation chamber recede to cause repetition of the valve-operating cycle.

Each of the thermostats 3l is tuned" or adjusted empirically to cause an overall or average pressure readings are taken at various parts of the system and along the traveling paper for guidance in ascertaining the optimum setting of each `thermostat 38. The thermostat setting is raised, of course, to increase the rate of fluid release, 4and is lowered to decrease the rate of release.'

` Since each valve 31 operates intermittently the increases in the overall or average rate of release by the valve may be raised either by increasing the frequency of the opening operations of the valve or by prolonging the periods of release or maximum release by the valve, or by increasing both the frequency and duration of valve operation. The raising of the temperature setting of a thermostat increases the rate of release flow by both of these expedients, since the higher the relative temperature in the pressure accumulation chamber when the valve closes, the more rapid is the subsequent drop in temperature to cause repetition of the valve operating. cycle, and the higher the temperature required Ato close thek valve the longer is the period required for that temperature to be built up in the pressure accumulation chamber. Preferably a combined pressure gauge and thermometer 59 is provided to indicate the pressure and temperature prevailing inside the pressure accumulation chamber or pipe 51.

The range of variation in the rate of fluid release by a valve 31 that may be covered simply by manipulating the setting of the corresponding thermostat 38, which range is adequate for many installations, islimited by the pressure and temperature prevailing in the receiver tank 36 and the pressure and temperature prevailing in the return line 32 above the valve 31. On the one hand, the temperature setting` of the thermostat 38 must be lower than the normal temperature above the release valve to cause the valve to be closed automatically in response to heat provided by the released fluid, and, on the other hand, the thermostat setting must be above the normal temperature in the receiver tank 35, because otherwise the temperature in the pressure accumulation chamber would never drop suiliciently to open the valve.

If greater iluid release or more frequent iluid release is required for a given installation than is available within the practical range of thermostat adjustment, it is necessary to change some factor other than the temperature setting of the thermostat, or to introduce some new factor. Among the factors that conceivably could be 7 changed are the rate at which fluid is released at the maximum open position of the valve and the restriction of flow by the spray nozzles. It`

has been found, however, that any change in these two respects involves conflicting or complicating factors. For example, increasing the rate of flow through the valve at the maximum open position of the valve increases the rate at which the temperature in the pressure accumulation chamber rises, and (thereby shortens the valve operating cycles. Decreasing the size or number of the spray apertures to hasten the rise in temperature for opening action of the valve, thereby to raise the overall rate of fiuid release, tends to defeat its purpose by restricting the capacity of the spray heads to handle the increased volume.

Wherever this dilemma is met the present invention solves the problem by the application of a cooling fluid to the thermostat 38, thereby introducing a factor that modifies other involved factors in a desirable manner. The application of a cooling fluid to the thermostat hastens the drop in temperature of the thermostat following closing of the valve, and thereby increases the frequency of the valve opening operation. When the valve is open to introduce the released fluid into the pressure accumulation chamber the applied cooling fluid prolongs the period of flow or maximum flow in two ways: first, by modifying i are retarding the heating effect of the released fluid, i. e., retarding a rise in temperature in the pressure accumulation chamber, and second, by counteracting to an appreciable extent the flashing of the released condensate with consequent retardation in the rate of pressure rise in the accumulation chamber.

The cooling fluid may be applied in various ways in various practices of the invention. A feature of the particular arrangement shown in Figs. l and 2 is the recycling of condensate from the receiver tank 36 for this purpose. In the construction shown the means for recycling the condensate includes a pipe 6U that branches from the pipe 43 between the pump 42 and the cut-olf valve 46. To insure suiicient pressure for adequate flow in the pipe 60 a pressure regulator valve 6| may be inserted in the pipe 43 beyond the cut-off valve, if desired, so that when the cut-off valve is open substantial pressure on the discharge side of the pump 42 will prevail. It is to be understood, however, that the pressure regulator valve 6| is not essential. The pressure setting of the regulator valve 6| will, of course, be less than the pressure setting of the relief valve 49 in the bypass 48.

The recycled condensate may be conducted to a suitable heat exchanger 62, where it is cooled by new water, the new water being supplied to the heat exchanger through a pipe 63 and being discharged therefrom into the previously mentioned supply pipe 50. From the heat exchanger 62 the condensate passes into a pipe 65 which, by preference, is equipped with an intermittently operated valve 66, although such valve may be omitted.

The valve 66 may be operated periodically in any suitable manner. The particular arrangement shown in disclosed in the previously mentioned copending application Serial No. 581,586, and includes a solenoid 61 that operates the valve in one direction in opposition to a return spring 68. The circuit for energizing the solenoid 61 is controlled by a suitable relay 10 in a control timer being adjusted to vary the frequency and/or duration of the open valve periods.

The pipe 65 that is controlled by the valve 86 is in effect a manifold for supplying cooling uid for each oi' the four thermostats 38, the cooling fluid being supplied through four corresponding branch pipes 13 equipped with individual adjustable valves 15. Preferably, as shown in Fig. 2, each of the pipes 51, comprising a part of the corresponding pressure accumulation chamber, is enlarged to provide an annular space 16 surrounding a jet nozzle 11 and a Venturi throat 18, and the corresponding branch pipe 13 communicate with this annular space. By virtue of this arrangement the fluid released from the valve 31 draws in the cool condensate from the branch pipe 13, and the condensate immediately enters into intimate mixture with the fluid released by the valve.

It is apparent that tuning of the master control 3| in the improved arrangement is quite flexible, since both the thermostats 38 and the four recycling valves 15 may be adjusted. In addition the cooling of the condensate by the heat exchanger 62 may be adjustable, but usually such additional adjustment is not at all necessary because manipulation of the thermostats 38 and the valves 15 cover such a Wide range of rates of fluid release. Adjustments may be made over the augmented tuning range with surprising precision.

Often the prevailing temperature in the receiver tank 36 is low enough relative to the temperature prevailing on the inlet sides of the release valves to make cooling of the recycled condensate unnecessary, so that in many instances the heat exchanger 62` may be omitted. The intermittent valve 66 may also be omitted. The use of such an intermittent valve, however, results in abrupt changes in the cooling action and causes abrupt pressure changes in the steam system. The abrupt pressure changes or pressure waves in the steam system have been found to have a highly desirable effect in increasing the rate of heat transfer in the various drying cylinders I8.

Fig. 4 indicates how air, instead of condensate, may be employed as the cooling liquid to introduce a modifying factor for increasing the inherent tuning range of the master control. The structure involved is largely identical with the structure heretofore described, as indicated by the use of corresponding numerals to identifycorresponding parts. Instead of introducing cooling condensate into the pipe 51 to affect the thermostat 38, a blower or fan is positioned to direct cooling air against the exterior of the walls inclosing the thermostat 38. Obviously the cooling stream of air will have the same general effect as the previously described cooling stream of condensate, but usually to lesser degree. The fan 80 is driven by a suitable motor in a housing 8|, and the speed of the motor is adjustable by a suitable variable control 82. In this arrangement tuning may comprise adjusting the speed of the blower 88 alone or in addition to adjusting the settings of the thermostats 38.

The invention may be embodied in other steam arrangements, as indicated by way of example in Figs. 5 and 6. Fig. 5 shows a master control, generally designated 89, including an upright receiver tank 90, and Fig. 6is a simplified diagram illustrating how such a master control may be incorporated in a steam system.

Fig. 6 shows the master control tank 90 connected to a feed water supply pipe 9| and connected to a boiler 92 by means of a boiler feed circuit 1| governed by a suitable timer 12, the u pump 83 and a pipe 94. The pump 93 may vary in operation in response to changes in the boiler water level by virtue of suitable automatic control means (not shown), or may operate at constant speeds subject to adjustment from time to time.

The boiler is connected by a steam linev 95 to one or more heat exchangers, Fig. 6 showing two heat exchangers 96. Instead of valves r oriiice members at the outlet sides ofthe two heat exchangers, the drawings show short lengths of relatively small pipe 91. The small pipes 91 are inserted in branches of a return line 98 that carries condensate and steam from the heat exchangers to the master control 89. Preferably, but not necessarily, a receiver tank 99 is inserted in the return line 98, as indicated, the receiver tank being closed from the atmosphere. Thus a clear trap-free channel is provided for the flow of steam from the boiler to the master control.

As shown in Fig. the master control tank 90 contains heated deaerated water having a normal upper level |00 determined by a float |0| controlling a valve |02 in the water supply line. Preferably an overflow pipe |03 is connected to the master control to keep the water level from rising substantially above this upper level |00.

When the water drops in level the iioat automatically opens the valve |02 to restore the water level. An auxiliary throttling valve |04 may also be placed in the water line, as shown.

The new water from pipe 9| passes through a condenser unit |05 having multiple ducts with exterior iins, the unit serving both to condense water vapor in the master control and to heat the new water initially. A suitable hood |06 may be provided to cause ascending water vapor to pass through the unit |05, non-condensable gases escaping through the vent |01 at the top of the master control.

From the condenser unit |05 the new water passes through the valve |02 and then into a mixing passage or pipe |08 that terminates in a plurality of downwardly directed spray or atomizing heads |09. The mixing passage provided by the pipe |08 corresponds in function to the previously mentioned pressure accumulation chamber in the first described form of the invention. Preferably a drip pan l l0 is placed adjacent the mixing pipe |08 to receive heat therefrom, the drip pan catching droplets of condensate from the unit 05 and overiiowing onto the body of water below. Heating the water in the drip pan results in the release of non-condensable gases from 'the water.

. The return line 98 of the system is connected to an injector or nozzle directed into the mixing pipe |08, the ow of steam and condensate to the nozzle being controlled by a thermostat valve ||2 ,in the return line. The valve ||2 opens in response to lowering of the temperature in the mixing pipe |08 to a` predetermined minimum and closes in response to rise of the mixing pipe temperature toy a predetermined maximum, being adjustable for various temperature settings. For such response the 'thermostat valve ||2 is providedwith a control tube terminating in a thermostat bulb I3 inside the mixing pipe |08. Preferably, as shown in Fig. 5, the spray nozzles |09 are higher than the portion of the mixing pipe |08 housing the thermostat bulb ||3 to favor normal envelopment of the bulb by a residue of water whenboth valves |02 and I2 are closed.

The desired cooling fluid forintroducing the modifying factor into the tuning combination l0 may be supplied by a suitable pipe 5'. connected with the pipe |08 adjacent the injector nozzle I The cooling fluid may be obtained from any suitable source and maybe circulated by any suitable means. In the particular construction shown the condensate accumulated in the bottom of the tank is recycled through the pipe III by a suitable pump |l6, and the rate of recycling fiow is controlled by a suitable valve ||1.

In the described arrangement shown in Figs. 5 and 6, the setting of the thermostat is, of course, substantially above the normal temperature prevailing in the master control tank 89, so that in the absence of any cooling aids whatsoever the thermostat bulb |I3 would drop in temperature to a point at which the thermostat valve or release valve l|2 would be opened. A continuous cooling eil'ect on the thermostat bulb is added by the condensate continuously recycled through the pipe H5, the modifying eiiect being the same as heretofore described.

An additional cooling eii'ect which automatically varies with the heat load on the system is aiiorded by the new water that is introduced into the mixing pipe 08 whenever the float controlled valve |02 is open. The operation of the valve |02 follows variations in the heat load, since increasing the heat load increases the demand for new water and therefore increases the amount of new water released into the pipe |08 by operation of the float |0I. It is to be noted, moreover, that whenever condensate removal from the system tends to' slow down. the liquid level |00 in the master control tank 90 tends to drop thereby to cause the control valve |02 to introduce new water with consequent cooling eil'ect on the thermostat bulb. Such cooling action hastens opening of the valve ||2 to hasten the removal of the condensate accumulated in the system. The cooling effect of the new water may be prolonged by simply throttling the ilow of the new water through the valve |02, the throttling action being accomplished in an adjustable manner by the valve |04. i

It is apparent that the system shown in Figs. 5 and 6 has all of the advantages of the rst described system, and the added advantage oi' automatically releasing steam in response to the addition of new water whereby the release of steam is desirably increased to a substantial extent whenever the heat load on the system is increased. l

Opening and closing action of the thermostat valve I2 creates beneficial pressure pulsations and velocity surges in the steam system. To increase the number of such pulsations and surges, suitable means may be provided to continually and automatically interrupt the flow of new water when the float |0| is down. Fig. 5 shows a solenoid valve |20 in the water supply pipe 9| for this purpose.

The solenoid valve |20 is in series with an automatic electric timer |2|, and a mercury switch |22. The circuit is traced as follows: lead |23, solenoidvalve |20, wire |24, timer |2|, wire |25, mercury switch |22, and lead |26.

The mercury switch |22 is mounted on the Iioat control mechanism to rock to a circuit closing position whenever the float I 0| drops sufElciently to open' the float valve |02. Thus whenever the float valve |02 opens the solenoid valve |20 is operated to repeatedly interrupt the flow of cooling water to the thermostat bulb H3. Such intermittent water flow causes the thermol1 stat valve ,.l I2 toopen and close repeatedly while the iloat is down.

The timer |2| may be of any suitable type. In one practice, the timer |2| is a well known control device that is adjustable to divide a 30 second period into an open valve period and a closed valve period in any desired proportion. For example, the solenoid valve may open for ten seconds and close for 20 seconds in repeated cycles of operation.

Fig. 7 shows an arrangement for using water other than recycled condensate for cooling the thermostat bulb. If soft water is available from the general water supply or if it is feasible to use water that has been treated for use in the steam system, this arrangement is suggested.

The structure shown in Fig. 7 is largely identical with the structure shown in Fig. 1, as indicated by the use oi.' corresponding numerals to designate corresponding parts. The new water i'or cooling the bulbs is supplied through the previously described cooling water manifold 65, and may be periodically interrupted by the timercontrolled valve 66. The condensate mixed with the introduced cooling water in the receiver is delivered to the pipe 43 by the previously mentioned pump 42 as heretofore described.

The receiver 36 may be under substantial pressure and the pipe 43 may lead directly to the boiler so that the condensate throughout the steam condensate cycle is maintained at relatively high pressure to avoid heat losses by excessive flashing. In all practices of the invention, the iluid released from the receiver by the vent arrangement may be used for various heating purposes. Examples of such use will be described later.

'lhe purpose of Fig. 8 is to illustrate how the action of cooling water on thermostat bulbs for promoting and controlling velocity in the return lines of the steam system may be supplemented by heat exchangers in the return lines for the same purpose.

Fig. 8 shows a master control 3| including a receiver 36 provided with a vent release |30. The vent release may serve, for example, to maintain a pressure on the order of 10 to 30 pounds in the receiver. The usual return lines 32 are connected with the receiver 36 through the usual thermostat-controlled valves 31 and water for cooling the thermostat bulbs is supplied through a cooling header 65 as heretofore described.

Each of the return lines 32 is provided with a heat exchanger |3| through which cooling water ilows for the pllrDOse of causing condensation of steam in the return line. Such condensation means that the iluid shrinks to only a fraction of its vapor volume, and, of course, such contraction in volume promotes flow in the return line.

It is apparent that a cooling uid from any suitable source may be employed in the series of heat exchangers |3I and that the cooler the medium the greater the flow-promoting eHect. In the particular arrangement shown in Figure 8, the cooling fluid is supplied by a conventional water treating apparatus which may not only treat the water but also deaerate the water.

The treated water under pressure and at, say, 220 F. flows through a pipe |32 having two branches |33 and |35. The branch |33 passes through a heat exchanger |36 where the water is cooled to say 185 and then enters the previously mentioned manifold 65 for cooling the thermostat bulbs controlling the valves 31. A suitable valve |31 operated by a iloat |33 may be provided to cut oi! the flow of cooling water whenever the liquid in the tank 33 reaches a predetermined maximum level. This arrangement insures that the receiver will not be flooded.

The heat exchanger |30 may be supplied with a cooling medium in any suitable manner. In the particular arrangement shown, new water to supply the water treating apparatus is used. The new water enters the heat'exchanger |33 through a pipe |40 and is carried oil.' to the treating apparatus by a pipe |4I.

The second branch |35 of the previously mentioned pipe |32 that supplies the treated water is provided with a suitable check valve |42 and is connected to the intake of a boiler feed pump |43. Liquid that accumulates in the receiver 30 is drawn off by a suitable pump |45, the output ot which is carried by a pipe -|43 to the previously mentioned pipe |35. Thus liquid trom the receiver 36 is continually supplied to the intake of the boiler ieed pump |43. The pump l|43 discharges into a boiler line |41 which has a number of branches, there being six branches |43 leading to the six previously mentioned return line heat exchangers |3| respectively and one branch |49 that by-passes all of the heat exchangers. The by-pass branch |49 connects with a pipe |53 that leads directly to the boiler. A pipe 5| is connected to all of the heat exchangers |3| to pick up the cooling water from the heat exchangers for delivery to the boiler pipe |50.

It will be noted that the duid pumped into the boiler feed line |41 i'or passage through the various heat exchangers |3| on its way to the boiler is make-up water mixed with condensate that has been returned through the various return lines 32.

Preferably the branch pipes |40 and |43 are provided with respective valves |52, which valves may be individually manipulated to vary the relative amounts oi water that flow through the various heat exchangers |3I. If there is reason for promoting velocity in one or more of the return lines |32 relative to the other return lines. the proportion of cooling water that flows through the corresponding heat exchanger or heat exchangers may be increased accordingly by manipulating the appropriate valve or valves |52.

A further possibility for increasing the velocity of ilow through any one of the return lines 32 is to adjust the corresponding thermostatic valve 31 at a higher setting than the rest of the valves to favor opening action of the valve. If desired, flow through any selected return line may be increased relative to the ilow through the remaining return lines by resorting to both of these methods of adjusting, that is to say, by increasing the ilow of cooling water through the correspending heat exchanger 3| and at the same time raising the temperature setting of the corresponding thermostat valve 31. The settings of the thermostats may be graduated in accord 'with a graduated series of rates of ilow or in accord with the quantities oi' condensate w be handled by the various return lines.

Fig. 9 is illustrative of various practices of the invention that involve utilizing steam from the receiver 36. The steam may be largely live steam drawn through the whole system or may be largely if not entirely, steam generated by the dashing action of condensate as it drops in pressure on entering the receiver.

Fig. 9 shows the usual master control 3| including the usual receiver 33. The various return lines J2 are connected to the usual thermostat- 13 controlledvalves 31 and a manifold 66 delivers cooling water to the thermostats as heretofore described.` A suitable pump |53 may be operated continuously to deliver liquid from` the master control tank 36 to a kboiler feed line |55. In the particular arrangement shown, whenever the liquidzcontcnt of the receiver 36 drops toa predetermined minimum level, a suitable float (not shown) in the tank opens a valve |56 in a` by-pass line |51 from the discharge side of the pump |53 to the master control tank for recycling of the iluid. This arrangement keeps the receiver from being pumped dry.

Steam from the receiver 36 in Fig., 9 is continually released through -a pipe |58 to a suitable point of use or disposal. A feature of the particular arrangement shown is that the steam is delivered to a low pressure steam-consuming device vand the resulting condensate is employed to cool the thermostat bulbs. In Fig. 9 the pipe |58 carries steam from the master control tank to a low pressure heater |60 and the condensate from to the previously mentioned cooling water mani! fold 65.

If desired, one or more expedients may be employed to insure that the liquid delivered to the manifold 65 is relatively cool. Thus Fig. 9 shows a pressure reducing valve |63 in the pipe |56 to drop the pressure of the steam supply to the heater |60. Such pressure drop means cooler condensate. A second expedient that may be used is a heat exchanger |65 for cooling the condensate as it passes through the manifold 65. Relatively cool water from any suitable source may be circulated through the heat exchanger |65 by means of pipes |66.

The various partsof Fig. 9 described up to this point may constitute a practical embodiment of the invention as will now be explained. The pressure in the receiver 36 will be determined on the one hand, by the rate at which fluid enters the receiver through the thermostat-controlled valves 31 together with the rate of inflow from the cooling manifold 65 and, on the other. hand, by the rate at which steam is drawn off -by the pipe |58. It is contemplated that the rate of withdrawal of steam from the receiver 36 through the pipe |58 will be suitably controlled to maintain the pressure in the master control tank in a selected range of pressures that the thermostat valves 31 will be adjusted to operate within the range of temperatures corresponding to that range of pressure. Preferably the settings of the various thermostat valves 31 will be graduated in accord with the condensate loads on the corresponding return lines 32, the higher the condensate load the higher being the setting of the corresponding thermostat valve.

For any given rateof fluid withdrawal from the receiver 36 by the condensate pump |53 and the steam line |58 the various thermostat valves 31 will release fluid from the return lines 32 at relative rates determined by the relative settings of the thermostat valves. The total release from the return lines under steady state conditions will tend to maintain some given equilibrium pressure with receiver. In practice the several thermostat settings must not extend over too wide a ran-ge otherwise the pressure in the master control tank will be sustained by the thermostat valves with the higher settings and the thermostat valves with the lower settings will not open at all.

The supply side of a steam system represented by Fig. 9 may be at 40 lbs. per square inch gauge.

'14 The pressure in the returnlines 32 may be approximately 35 lbs. and the pressure in the receiver 36 may be in the range of 10A to` 30 lbs. gauge. If, for example, the master control tank is at' 36 lbs., the pressure reducingvalve |63 may ser've to drop that pressure to approximately 12 lbs. gauge. l

The plurality of. thermostat valves 31 will respond automatically to any changes in therate of iluid .released from the master control tank. Suppose, for example, that a state of equilibrium exists with a constant release of iluid from the tank and that the pressure in the tank is at 30 Conversely, if for any reason the rate of fluid 'release from the receiver is decreased, the -pressure s in the receiver will rise to a new equililorium and this heater is delivered by a suitable pump |62 f' release from the return lines.

the consequent higher temperature in the receiver will cause the thermostat -valves to' reduce4 the Fach thermostat -valve l responds directly only to temperature changes as-distinguished from pressure changes, butternperature in the receiver varies directly with steam pressure so that the valves respond indirectly to pressure changes. i y

It is to be understood thatin all instances the thermostat may be slow acting or quick acting and may completely close or only partially close.

In some practices of the invention steam may be released from the receiver 36 through a pipe |61 leading to a remote deaerator tank |10, the release through the pipe |61 either supplementing the release through the pipe |58 `or replacing the release through the pip |58.

In Fig. 9 the master control tank is shown diatgrammatieally in plan but the deaerator is shown diagrammatically in elevation. The layout indi-- cated in Fig. 9 is suggested for steam plants in which the logical and convenient point for the collection of condensate by a receiver is a considerable distance from the boiler room where deaeration requiring considerable steam is carried out. The demand for steam for deaeration is met in part bythe steam from the receiver.

In the particular arrangement shown in Fig. 9, thelpipe |61 for conveying steam from the mas-- ter control tank 36 is connected to ak heat exchanger |1| in the boiler room and the heat exchanger in turn is connected to the deaerator tank |10 by a pipe |12, the connection being above the liquid level in the deaerator tank. Cold water for make-up is supplied through a pipe |13, having a valve H5 that responds to a oat control |16 on fthe deaerator tank. The water flows through a condenserv |11 for condensing vapors inthe upper end of the tank and then passes through a pipe |18 to a coil |80 inside the heat exchanger |1|. From the coil |80 the heated water is carried by a pipe |8| to a spray head |82 inside the deaerator tank above thepoint of discharge of the previously mentioned pipe |12. This spray head has downwardly directed spray openings so that the released water is directed towards the condensate or condensate and steam that is discharged from the pipe |12.

The deaerator tank |10 has at the top a relief pipe |15 controlled by a relief or safety valve |15 atmosphere may be a simple manual valve that is adjusted from time to time as required to permit continuous release of fluid at a rate to maintain a desired approximate nornal pressure in the deaerator tank. It is contemplated that the arrangement and the various adjustments will be such that the fluid escaping to the atmosphere through the -vent pipe |81 willI be mostly, if not entirely more condensible gases isolated by the deaeration action.

Fig. 9 shows a pair of boiler feed pumps |90 and |9| connected in parallel to the bottom of the deaerator tank |10 by a pipe |93. The two pumps, one of which will serve as a stand-by pump, are connected to common discharge pipe |93 leading to the previously mentioned boiler feed line |55. If desired, a valve |95 in a by-pass pipe |96 may be opened to cause condensate from the receiver 36 to be delivered to the deaerator tank |10 instead of directly to the boilers. Also if desired a valve |91 in a by-pass pipe |90 may be opened to cause the cold water supply to go directly to the intake sides of the boiler feed pumps |90 and |9| instead of directly to the deaerator tank |10.

It is assumed in Fig. 9 that the pressure drop between the receiver 36 and the deaerator tank |10 caused by the relatively long pipe |61, the heat exchanger |1|, and the pipe |12 will be such that the relative pressures in the two tanks will be at desired values. If a greater pressure difference is required than can be provided by-normal flow resistance, a greater pressure drop may be provided by using restrictions or using a pressure reducing valve, which expedients are weil known to the art.

In one instance, by way of example, the pressure in the receiver 86 may be 10 lbs. gauge and the pressure in the deaerator tank 5 lbs. gauge with a pressure drop of 5 lbs. between the two tanks and a final pressure drop of 5 pounds across the partially opened vent valve |86. Preferably the deaerator tank is provided with' a suitable pressure gauge 200 for guidance in adjusting the valve |86. In other instances the pressure in the master contro1 tank may be relatively high, say 30 or 40 lbs. gauge, for the sake of direct return of condensate to the boiler without substantial reduction in the pressure of the condensate.

The deaeration action in the tank |10 is well known operation. The newly introduced water is heated in two stages: rst, in the condenser |11 and second, in the coils |80 of the heat exchanger |1|. The water reaches the spray head |92 at relatively high temperature and at greater pressure than the pressure prevailing in the deaerator tank.

The release of the heated Water through the spray openings into the region of lower pressure causes separation of non-condensible gases from the water and further separation occurs as the spray encounters the heated discharge from the pipe |12. The cooling action of the spray is such as to condense substantially all the vapors released by the pipe |12 and any residual vapors that exist are turned into water by the condenser.

Fig. 10 illustrates diagrammatically another practice of the invention in which steam is continually drawn from the master control tank at a rate to maintain a predetermined pressure or range of pressures therein. The concept here is 18 steam from the master control receiver 86 through the supply header 208.

High pressure steam from a high pressure supply line 281 is supplied to the high pressure inlet of the jet-compressor 208 for discharge from an enclosed Jet nozzle 208 (Fig. l1) into a Venturi throat 2|0. Steam from the receiver'36 is carried by a pipe 2|| to the low pressure inlet of the iet-compressor 205 for intermixture with the high pressure steam in the venturi. The

discharge from the jet-compressor 205 is carried by a pipe 2|2 to the supply header 206. The header 208 feeds the various cylindrical driers |0 which are constructed and arranged as heretofore described.

The driers |8 are grouped in the usual manner for delivering condensate to the receiver through a plurality of return lines. Fig. 10 shows a return header I8 connected to one of the return lines 82 and shows fragments of the remaining return lines. Each of the return lines 92 is controlled by the usual thermostat valve 31, and if desired, each of the thermostats may be supplied with relatively cool water to favor opening action of the valve as heretofore described. Condensate is continually withdrawn from the receiver 36 by the usual pump 42.

As an example of operating conditions, steam supplied to the Jet-compressor 205 through the pipe 201 may be at lbs. gauge and the receiver 36 may supply steam at approximately 40 lbs. gauge. The jet-compressor will supply steam to the header 208 at some intermediate value, say 60 lbs. gauge.

Preferably some provision is made for maintaining the desired pressure relationships automatically. For this purpose, Fig. 10 shows a pressure regulator 2|8 in the high pressure steam line 201. Atube 2|6 extends from the pressure regulator 2|8 for response to the discharge side of the jet-compressor 206 so that the pressure regulator may maintain a predetermined pressure differential across the jet-compressor. In addition, a suitable ipressure reducing valve 2|6 may be inserted in the pipe 2| to release steam from the receiver 86 at a controlled rate that will insure maintenance of the desired back pressure in the receiver.

We claim as our invention:

1. In a steam system, at least one steam using device, a steam supply connected with the inlet side of said device, a closed receiver, a return line from the outlet of said device to said receiver to carry fluid thereto, a valve controlling release of fluid from said return line into said receiver, said device and return line forming a continuous open channel from said steam supply to said valve, a thermostat operatively connected to said valve to cause opening action of the valve at temperatures below the thermostat setting and closing action of the valve at temperatures above the thermostat setting, said theromstat being positioned to be heated by the fluid released by said valve and having a setting above the temperature prevailing in said receiver and below the temperature prevailing in said return line, a device using steam at a lower pressure than said steam supply, means to supply flash steam from said receiver to said low pressure device and means to convey the condensate from said low pressure device into heat exchange relation with said thermostat for cooling of the thermostat.

2. In a steam system, a combination as set forth in claim l in which said valve discharges to employ a jet-compressor 205 to recycle the 18 into a passage leading to spray openings in said 17 receiver and in which said thermostat is positioned in said passage. i

3. In a steamV system, a combination as set forth in claim 1 in which means is provided to reduce the pressure of the steam suppliedto said low wpressure device substantially below the pressurein said receiver.

4. In a steam system, a combination as set forth in claim 1 in which heat exchange means is provided to cool the condensate before the condensate reaches said thermostat/ 5. In a steam system, a plurality of steam using devices, a steam supply connected with the inlet sides of said devices, a receiver-under substantially less pressure than said steam supply, a plurality 'of`return lines from said devices to', said receiver, a valve controlling the release of fluid from each of said return lines into said receiver, said devices and return lines forming continuous open channels from said steam supply to said valve, a thermostat operatively connected to each of said valves, said thermostat being positioned to be heated by the fluid released by the valve, said thermostat having a temperature setting above which it causes closing action of the valve and below which it causes opening action of the valve, said setting being below the temperaturein the corresponding return line but above the temperature in the receiver, the settingsl of said thermostats being varied in accord with desired relative rates of flow in said return lines, and means to deliver uid from said receiver at a rate to maintain the pressure and temperature therein below the pressure and temperature in said return lines.

6. In a steam system, a combination as set forth in claim 5 which includes means to apply a cooling fluid to said thermostats.

7. In a steam system, a combination as set forth in claim 5 in which each of said valves discharges into a-corresponding passage leading to.

the release of fluid from each of said return lines into said receiver, said steam using devices and return lines forming continuous open channels from said steam supply to said valves, a thermostat operatively connected to each of said valves, said thermostat being positioned to be heated by the fluid released by the valve, said thermostat having a temperature setting above which it causes closing action of the valve, and below which it causes opening action of the valve, said setting being below the temperature in the corresponding return line but above the temperature in the receiver, a plurality of passages corresponding to said thermostats for conducting cooling fluid into heat exchangerelation with the thermostats to cause opening action of the corresponding valves, and a plurality of valve means for varying the flow of the cooling fluid through said passages.

9; In a steam system, a plurality of steam using devices, a steam supply connected with the inlet l side of said devices, a receiver, a plurality of return lines for conveying uid from said devices 4steam supplyto'said valves, a thermostat operatively connected to each of said valves. said thermostat being positioned to be heated by the fluid released by the valve, said thermostat having a temperature setting above which it causes closing action of the valve and below which it lli/causes opening action of the valve, said setting being below the temperature in the corresponding return line but above the temperature in the receiver, and means to draw fluid from said receiver at -a rate to maintain the desired pressure therein.

19. In a steam system, a combination as set forth in claim 9 which includes means to apply a cooling fluid to each of said thermostats.

11. I n a steam system, a plurality of steam using devices, a steam supply connected with the inlet sides of said devices, a closed receiver, la plurality of return lines from said devices to said receiver, a valve controlling the release of iluid from each of said return lines into ,said receiver, said steam using devices and return lines forming continuous' open kchannels from said steam supply to said valves, a thermostat operatively connected to each of said valves, said thermostat being positioned to be heated by the fluid released by the valve, said thermostat having a temperature setting above which it causes closing action of the valve and below which it causes opening action of the valve, said setting being below the temperature in the corresponding return line but above the temperature in the receiver, and means to draw flash steam from said receiver at a rate to maintain the pressure of the receiver Within a given range below the pressure prevailing in said return lines.

12. In a steam system, a plurality of steam using devices, a steam supply connected with the inlet sides of said devices, a closed receiver, a

plurality of return lines from said devices to said receiver, a valve controlling the release of fluid from each of said return lines into said receiver, said steam using devices and return lines forming continuous open channels from said steam supply to said valves, a thermostat operatively connected to each of said valves, said thermostat being positioned to be heated by the fluid released by the valve, said thermostat having a temperature setting above which it causes closing action of the valve and below which it causes opening action of the valve, said setting being below the temperature in the corresponding return line but above the temperature in the receiver, a deaerator tank remote from said receiver, means to remove flash vapor from said discharges into a corresponding passage leading to spray openings in said receiver and in which the corresponding thermostat is positioned in said corresponding passage.

14. In a steam system, at least one, steam using device, a steam supply, a jet-compressor having a discharge outlet connected to the inlet sides of said devices, a high pressure inlet connected with said supply and a low pressure inlet, a closed receiver, a return line from the outlet of said device'to said receiver to carry fluid thereto. a

valve controlling release oi fluid from said re- I turn line into said receiver, said devices and return line forming a continuous open channel from said jet-compressor to said valve, a thermostat operatively connected to said valve to cause opening action of the valve at temperatures below the thermostat setting and closing action of the valve at temperatures above thev thermostat setting, said thermostat being positioned to be heated by the iiuid released by said valve and having a setting above the temperature inl said receiver and below the temperature in said return line, means to convey steam from said receiver to said low pressure intake of the jet-compressor and means w release condensate from said receiver.

15. In a steam system, a combination as set forth in claim 14 which includes means to apply a cooling iluid to said thermostat.

Elim PAUL HARRISON.

ORVIILE A. HUNT.

LOUIN TRIER.

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

UNITED sTATns PATENTS 5 lines.

15 Number Name Date 2,001,344 Fielder May 14. 1938 2.321.235 Olson June 8, 1943 2,386,332 Harrison et al Jan. 2. 1945

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