US2208947A - Control system for refrigerating apparatus - Google Patents

Description

July 23, 1940. A. A. MARKSON CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed April 26, 1938 5 SheetsSheet l INVENTOR A. A. MARKSON CONTROL SYSTEM FOR REFRIGERATING APPARATUS July 23, 1940.

FiledApril 26, 1938 5 Sheets-Sheet 2 INVENTOR Mfmm/wm I lllnll July 23, 1940. A. A. MARKSON CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed April 26, 1938 5 Sheets-Sheet 5 July 23,1940. A. A. MARKSON CONTROL SYSTEM FOR REFRIGERATING APPARATUS Filed April 26, 1938 5 Sheets-Sheet 4 QTL 3 July 23, 1940. A. A. MARKSON CONTROLSYSTEM FOR REFRIGERATING' APPARATUS Filed April 26 1938 5 Sheets-Sheet 5 y -"W W Patented July 23, 1940 PATENT OFFICE ooN'rnor. SYSTEM FOR REFRIGERATING,

APPARATUS Alfred A. Markson, Kew Gardens, N. Y. Application April 26, 1938, Serial No. 204,325

7 Claims.

This invention relates to refrigerating apparatus of the type in which the refrigerant or the material to be cooled, for example, water, is cooled in a tank which is maintained under partial vacuum by means of steam actuated vacuum creating devices of the Venturi or evactor type, and more particularly to a control system for maintaining the proper relationship between the absolute pressure in the flash tank and the absolute pressure in the condenser into which steam, air and water vapor are discharged by controlling the rate of delivery of cooling water to the condenser.

In refrigerating systems of the type referred to above, whether they be used for air conditioning or for providing a supply of cooled water for ofiice buildings, and the like, the water to be cooled, which, for convenience will be referred to asthe refrigerant, is delivered from a source of supply into a flash tank or vacuum chamber in which it is cooled and. from which the cooled water is circulated to wherever needed. One or more boosters or steam jet compressors of the Venturi or evactor type are connected to the flash tank and to the water-cooled condenser. By supplying steam to these boosters, steam passes through them at high velocity and picks up vapor released from the water supplied to the flash tank, compresses and transfers it to the condenser. As the vacuum increases in the flash tank, the boiling point of the water is lowered, whereby some of the water is vaporized by the heat of the liquid, causing the temperature of the remaining liquid to be reduced. The higher the vacuum maintained in the flash tank, the lower the temperature of the liquid remaining therein will be. For example, if the pressure in theflash tank is reduced to a value of say, 0.2575 inch of mercury absolute pressure, the temperatureof the water in the tank will be about 4.-1 F. 40 In some localities the cost of steam required for operating the boosters may be high. compared to the cost of water required for proper operation of the condensers, and in some cases the cost of condenser cooling water may be high compared to the cost of steam. Where the cost of steam is high compared to the cost of condenser cooling water, it' is economical to control the pressureof the steam delivered to the boosters in accordance with the difference between the flash tank and condenser pressures. A system for controlling the steam pressure in accordance with the difference between the flash tank and the condenser pressure is disclosed and claimed in my co-pending application, Serial No. 6,653, filed February 11,1935.

The present application has to do with the provision of a system for controlling the rate of delivery of cooling water to the condenser in accordance with the difference between the pressures in the flash tank and the condenser. The control system embodies also other features which will be pointed out hereinafter.

Refrigerating apparatus of the type referred to herein is provided with one or more boosters or steam jet compressors connected in multiple to a steam supply header, and the number of boosters employed at any one time is dependent upon the refrigerating load. Each booster or compressor may include one or a group of nozzles and the steam in passing through them is converted from pressure head into velocity head which is high enough to overcome the back pressure in the condenser and compress and transfer air and water vapor from the flash tank to the condenser. Where one or more steam jet compressors are employed, it is customary to provide one or two of such compressors with manual control so that they'will be in operation all the time except when shut down, while the other steam jet compressors may be controlled automatically in accordance with the temperature of the water in the flash tank. Sometimes a cyclic control is employed which allows the automatic boosters to come into operation only during certain hours of a 24-hour period and though available during such a period, they are subject to control in accordance with the temperature of the chilled water, i. e., such automatic boosters are turned on or oil as determined by load requirements.

Where the cooling water to the condenser is controlled from the difference between the flash tank and the condenser pressures, and assuming that the cost of steam is appreciably less than that of the cooling water, the steam pressure is supplied to the steam jet compressors at a value which will insure continuity of operation. Such continuity of operation requires that the difference between the flash tank and the condenser pressures be maintained substantially constant, and the closer the steam pressure is to the minimum efiicient operating value, it becomes more and more important that this pressure differential be maintained at a substantially constant value.

When one or more boosters are maintained in operation all of the time, the control system operates to regulate the fiowof condenser water in such manner that a substantially constant difference between the flash tank and condenser pressures is 2 maintained. When such a differential is maintained substantially constant the pressure of the steam supplied to the steam jet compressors; may be of avalue just slightly above the minimum pressure required to secure continuity of operation thereof. If the steam pressure is maintained slightly above the critical operating value, then it will be apparent that, when more boosters are put in operation, the rate of supply of cooling water to the condenser must be increased before additional boosters are put on in order to insure that the condenser pressure will not rise to a value high enough to cause one or more of the boosters to break and to stop functioning.

The control system to be more fully described herein is adaptable to steam jet refrigerating apparatus having one or more manually-controlled compressors, and one or more automatically-controlled compressors, or to cases where all of these boosters are under automatic control.

An object of this invention is to provide a control system for steam jet refrigerating apparatus that will maintain a substantially constant difference between the flash tank and the condenser pressures. by regulating the supply of cooling water to the condenser.

Another object of the invention is to provide a control system that will function to increase the supply of cooling water to the condensers whenever the number of boosters in operation is increased.

A still further object of the invention is to provide a control system whereby one or all of the steam jet compressors may be controlled automatically and whereby the condenser cooling water may be automatically controlled to maintain a substantially constant differential between flash tank and condenser pressures and at the same time temporarily increasing the rate of supply of condenser cooling water before a booster is put in operation.

Where cooling towers are employed for cooling the condenser water, there are times when perhaps the capacity of the cooling tower is exceeded, in which case there'would not be available sulficient cooling water to maintain the differential between flash tank and condenser pressures desired. In such case, according to this invention the cooling tower water would be supplemented by an auxiliary supply of cool water and this auxiliary supply could be controlled either in accordance with the temperature of the cooling tower water or from the automatic control system. Where an auxiliary supply of cooling water is used, the control system would function to introduce water from the auxiliary supply only at such times as more boosters are put into operation, or only at such times as the capacity of the cooling tower is exceeded.

, It is also an object of this invention to provide a control system whereby in the case of cooling towers auxiliary apparatus may be putin operation, such as cooling tower fans, pumps, etc. whenever the magnitude of the load on the refrigerating system requires that such auxiliary apparatus be put in operation. a

- Other objects of the invention will, in part, be

apparent and will, in part, be obvious from the following description taken in conjunction with the accompanying drawings in which:

of the invention;

Fig. 2 is a View partly in section of a regulator embodied in the control systems;

Fig. 3 is a View in side elevation of the refrigerating apparatus of Fig. 1, with a detailed but diagrammatic illustration of apparatus for effecting automatic control and regulation of condenser cooling water and of the operation of a steam jet booster or compressor;

Fig. 3a is a View in section of an operating mechanism for valves employed in the control systems of Figs. 1, 3, 4 and 5;

Fig. 4 is a View of a modified form of control apparatus embodying the invention;

Fig. 5 is a view illustrating a still further modified form of control apparatus;

Fig. 5a is a view illustrating a modified form of control relays that may be utilized in the control apparatus of Fig. 5; and

Fig. 6 is a view of control apparatus adapted for automatic regulation and control of cooling tower systems and auxiliary water supply systems for steam jet refrigerating apparatus, and of auxiliary equipment associated therewith.

Throughout the drawings and the specification, like reference characters indicate like parts.

The refrigerating apparatus to which the control system embodying this invention may be applied, is illustrated more or less diagrammatically in Figs. 1 and 3 wherein numeral l designates the flash tank in which the refrigerant is cooled, for example water, and 2 designates a water-cooled steam condenser. A plurality of steam jet compressors or boosters 3, 4 and 5- are connected to the interiors of flash tank I and condenser 2, and when in operation pick up vapor from the flash tank, compress it and deliver it to the condenser wherein the steam and vapor is condensed. Compressors or boosters 3, 4 and 5 are provided with one or more steam nozzles 6 which are supplied with steam from a steam header 1. The boosters 3, 4 and 5 are also provided with shut-off valves 8, 9 and Ill respectively, whereby when a booster is taken out of operation communication between the flash tank and condenser may be cut off to avoid a transfer of vapor and uncondensed steam from the condenser to the flash tank.

Water to be cooled in the flash tank is supplied from a supply pipe H connected to a spray head l2 located within the flash tank. 7

The chilled water discharges from the tank into a pipe I3 and is circulated through the cooling system, not shown, by means of pumps, not shown.

Cooling water for the condenser is delivered to the condenser by a supply pipe M, the rate of delivery of cooling water to the condenser being controlled by a valve 15. The condensate in the condenser of course is discharged to drain by means of pumps, not shown, as is well understood in this art. The condenser would also be provided with an evactor for removing air and vapor from the condenser as is known in this art.

If steam-operated refrigerating apparatus of the type herein illustrated is provided with a plurality of boosters, one or two of them are usually manually controlled and the additional boosters are put under automatic control. The number of manual boosters is usually determined by the base or minimum load which the system must handle, the number of automatic boosters being usually determined by the peak load to be carried. The operation of the automatic boosters is usually controlled from the temperature of the chilled water or refrigerant in the flash tank, theautcmatic boosters beingturned on or 011', depending upon the chilled water temperature.

The invention embodied in the control system herein illustrated contemplates the provision of means for so automatically regulating the condenser cooling water-control valve ii that a substantially constant difference between the absolute flash tank and condenser pressures is maintained. To accomplish regulation of water-regulating valve i5 in this manner, a regulator I! is provided which responds to the difference between absolute pressure in the flash tank and the absolute pressure in the condenser, and eiiects operation of the water-control valve I 5 in accordance with such difference. Thus if it is desired to maintain the temperature of the chilled water discharging from the flash tank at a predetermined temperature of say X F., an absolute pressure P1 is required in the flash tank. To insure continuity of operation of the boosters, an absolute pressure P2 is required to be maintained in the condenser; therefore regulator i! must so regulate the flow of condenser cooling water that the value of (Pa-P1) is maintained substantially constant. Regulator I! would then be adjusted for balance for a predetermined value of (P2-P1). Whenever the value of (Pr-P1) changes, regulator i! will cause the water regulating valve Iii to change the rate of flow of cooling water through the condenser. If the value (P 2P1) increases, the rate of supply of water to the condenser must be increased, and if the value (PzP1) decreases then the rate of supply of cooling wateris decreased.

With such a system the pressure at which steam is supplied to the steam nozzles of the compressors would be set at some predetermined constant value, which value would be high enough to insure continuity of operation for a given value of (Pa-P1) As stated previously herein, one or more of the steam jet compressors or boosters may be manually controlled or operated, and one or more may be under automatic control. For purposes of description and illustration it may be assumed that compressors 3 and 4 are manuallycontrolled boosters or compressors, and that compressor 5 is under automatic control.

Assuming that it is desired to start the re frigerating apparatus, then the circulating pump for the cooling system is started, the condensate pumps for the condenser and the air and vapor ejectors therefore are also started .up and the cooling water for the condenser is turned on. During starting the cooling Water may be turned on full by means of a hand-controlled valve 19 located in a by-pass 2!] around the automaticallyoperated valve. The steam pressure is. then turned on to nozzles 6 of the boosters 3 and 4 and when these are operating the shut-01f valves 8 and 9 are opened up wide. After these valves have been opened the vacuum developed. by boosters 3 and 4 reduces the pressure in the flash tank. As the pressure in the flash tank is lowered water vapor is released from the water therein, is compressed by the steam flowing at high velocity through the Venturi sections of boosters 3 and 4 and is discharged into the condenser where the same is condensed. When boosters 3 and 4 have been in operation long enough to bring about approximately the predetermined value of pressure diflerential (Pz-l?1), manually-operated control valve l9 may be closed because bythistime regulator I! will be funcon'ing to position valve 15 at approximately the proper degree of opening.

the

The water-control valve I5 is of the diaphragmoperated type and comprises a diaphragm chamber 2! in which a diaphragm 22 is located (see Fig. 3) and connected to move stem 23 of the valve either up or down, depending on the pressure. If the pressure is atmospheric, or some predetermined value other than atmospheric, in the diaphragm chamber, the valve will be in its wideopen position, and as this pressure is increased the valve moves toward closed position, finally reaching a full closed position when the pressure is at a maximum.

Regulator ll responds to the difference between the pressures in the flash tank and in the condenser to position the automatically-controlled valve at the desired degree of opening. The regulator comprises a diaphragm 24 which is located in a diaphragm housing 25, an escapement valve 26 and a lever or beam 2'! which is fulcrumed on a knife edge 28 and connected to escapement valve 25 and diaphragm 24 by means of linkage 29. Both sides of the diaphragm are sealed by means of auxiliary or sealing diaphragms 30 and BI and the space below diaphragm 24 is connected by a pipe 32 to the condensing space of condenser 2 and the space above is connected by a pipe 33 to the vacuum space of tank I. The diaphragm therefore responds to the difference between P2 and P1.

Lever 27 is urged downwardly by means of a spring 34, the tension of which may be adjusted in accordance with the value of (P2--P1) to be maintained. If the lever or beam moves upward- 1y, valve 26 is adjusted toward its closed position, thereby reducing the .pressure transmitted to the diaphragm chamber of water-control valve it. As this lever moves downwardly, escapement valve 26 is opened wider and wider, finally reaching a full open position, thereby increasing the pressure delivered to the diaphragm chamber of the control valve iii in accordance with the degree of opening of the escapement valve. The lower side of the differential diaphragm is connected by means of a spring 35 to a piston 33 of a dashpot mechanism having fluid 37 therein (see Fig. 2). As seen in Fig. 2 the piston operates in a cylinder 33, the upper end of which is enlarged. The lower end of the cylinder communicates with the interior of a pressure responsive mechanism 39, such as a bellows, disposed Within a pressure tight housing or chamber 40. The portion of the cylinder located well above the dashpot piston 36 communicates with the space below the piston by means of a passage 4| that is controlled by a needle valve 42. The pressure chamber 40 is connected by a pipe 42 to sending line d3 of the regulator so that bellows 39 is always subjected to a pressureequal to the value of pressure transmitted from the escapement valve to the watercontrol Valve Hi. The dashpot mechanism tends to stabilize the operation of the regulator and to resist movement of the pressure responsive diaphragm 23 in either direction by imposing a force tending to resist such movement thatis proporthe water-control valve to reach a new or differentcontrol position before its position is again change by regulator l1. Thus regulator l1 gradually causes valve l to reach a position, without over or under shooting, that will establish the rate of supply of cooling water to the condenser required to maintain the differential value (P2-P1) at the desired magnitude. The operation of regulator I! as described above, and particularly the effect of the dashpot thereon, is described in my aforementioned co-pending application.

The escapement valve 26 comprises a valve body 44 having a substantially conically shaped inlet port seat 45 at its upper end and a similarly shaped exhaust port seat 46 at its lower end, and a valve member 41 having tapered surfaces at its opposite ends disposed to cooperate with the inlet and exhaust port seats, and moves therebetween in accordance with the position of the diaphragm 24. Valve body 44 has an outlet port 48 connected to sending line 43 which supplies pressure for operating the Water-control valve 15. If valve member 4'! is in a position to close inlet port 4-5 the pressure medium in sending line 43 and that transmitted to the diaphragm housing of valve I5 is exhausted to the atmosphere through the exhaust port; if the exhaust port seat is closed by valve member 4'1, the pressure in the sending line and that in the diaphragm housing of valve I5 Will be a maximum. For every position between the extreme positions above mentioned, the transmitted control pressure will be proportional to the position of valve member 41.

The air supply for operating the water-control valve l5, and which is under the control of the escapement valve 26, is supplied from an air line 56 through a filter 5| which removes extraneous foreign matter and a pressure-reducing valve 52 which not only reduces the pressure but also tends to maintain the pressure delivered to the inlet port of valve 26 constant. In order that the pressure at the inlet of escapement valve 26 may be maintained constant no matter how much air is transmitted thereby to sending line 43, a volume tank 53 is provided which acts somewhat as an accumulator to smooth out such pressure fluctuations as might otherwise develop through variations in the amount of air transmitted through the escapement valve.

The control system illustrated in Fig. 3 for effecting automatic on and ofi control of automatic booster or compressor 5 performs several functions, i. e., it turns this booster on when the chilled water temperature rises to a predetermined high value and shuts it off when the temperature reaches a predetermined low value. But in addition to these primary functions it also operates to temporarily increase the flow of water through the condenser for a period of time before the booster is turned on so that the condenser pressure will not rise too a value that would increase the back pressure on the boosters that-are in operation to the point where they might break or stop functioning when the automatic booster is turned on. The system also causes shut-01f valve ID to open after the valve which controls the admission of steam to nozzles 6 of booster 5 has been fully opened. When the booster is turned off, the control system operates to close valve Ill before the steam-control valve is closed, thereby in both cases guarding against the possibility of blow back from condenser 2 into the flash tank I.

As shown in Figs. 1 and 3, regulator H is provided with a target or cup-like member 55 secured to the free end of beam 21 and which is so positioned that the beam will move upwardly to close escapement valve 26 in response to the impingement of a blast of fluid, such as air, in the cup. The blast issues from a jet 56 connected to a storage tank 51. Tank 51 is charged with air from supply pipe 50, the charging of the same being under the control of a solenoid-operated valve 58, the operation of which is under the control of the control system. The air supplied to tank 51 passes through a filter 59 and a reducing valve 60 which also acts to regulate and maintain the pressure of the air as delivered to the tank substantially constant. The control system functions to allow valve 58 to remain open for a period of time that is long enough to charge tank 51. As the air discharges from the tank through jet 56, regulator I! will cause control valve l5 to open wide whereby the rate of cooling Water to condenser is increased and the pressure in the steam-condensing space of the condenser is reduced. After a predetermined length of time, the control system operates first to turn on steam to nozzles 6 of compressor 5 and then, after a lapse of time, to open valve In. When the steam valve is opened valve 58 is closed. When all of the air has escaped from tank 51, regulator I! will function normally again to regulate the water-control valve l5 in accordance with the difference between the absolute condenser and flash tank pressures. Since the charging and discharging of tank 51 requires time and since the pressure therein builds up gradually and reduces gradually, normal operation of regulator I1 is gradually and smoothly restored.

The control system includes also a thermostat or temperature-responsive device 62 having moveable contact member 63 and spaced stationary contact members 54 and 65, a relay 66 which controls the transmission of a pressure medium such as compressed air to operating mechanism (ill of valve I0 and to the operating mechanism 68 of valve ,69 which controls the admission of steam to nozzles 6 of compressor or booster 5, and a time-delay device which operates to control or initiate the operation of relay 66 a predetermined length of time after valve 58 has been opened. Relay 66 when energized also operates to cause valve 58 to close.

Relay device 66 comprises a solenoid 1|, an armature I2 havingspaced contact members 13 and 14 thereon, and a valve '15 similar to escapement valve 26, and stationary pairs of contact members 13a, and 13b and 14a and 14b. When solenoid I! is deenergized, moveable contact member 74 bridges contact members 143, and 1411 thereby partially preparing the energizing circuit of solenoid ll of valve 58, such circuit being completed when thermostat contact member 63 engages contact member 64 in response to the temperature of the chilled water in tank I reaching a predetermined high value.

The time-delay device 16 is of the pressure actuated type and comprises a housing 18 having therein a pressure responsive element 19, such as a bellows, and a switch element 86 adapted to be moved by the bellows into or out of contact with spaced stationary contact members 8% and 80b disposed in circuit with the solenoid H of relay device 66 and which when closed initially energizes solenoid H.

Air pressure for operating time-delay device 10 is transmitted to its housing from tank 5'! through a pipe 8| in which is disposed a needle valve 82 or other similar device, which delays the building up of the pressure in housing 18. When the pressure in this housing has reached a predetermined value its switch element engages the stationary contact members 80a and 80b thereof.

If it is assumed now that temperature of the Water in flash tank I is at a predetermined high value and that contact members 63 and 64 of the thermostat are in engagement, the energizing. circuit for solenoid I8 is established that extends from electric supply line L1 through a manuallycontrolled knife switch 83, contact members 63 and 64 of the thermostat, conductor 84, contact members 14, 14a and 14b of relay 66, conductor through solenoid 11 of valve 58 to electric supply line L2. On the energization of solenoid 11, valve 58 opens allowing air to pass into tank 51. As the pressure in tank 51 builds up, pressure begins to build up in housing 18 of time-delay device 78 and when this pressure reaches a predetermined value, contact member 80 engages contact members 80a and 80b, thereby establishing a circuit for solenoid H of relay 66. This circuit extends from L1 through the contact members of timedelay device 78, conductor 86, through solenoid H and adjustable resistor 81 to line L2. When this coil is energized the relay operates to disengage contact member 14 from contact members 14a andlds, to engage contact member 13 with contact members 13a and 13b and to open valve 15. When this occurs the circuit for the solenoid of valve 58 is deenergized causing valve 58 to close, and a holding circuit is established for solenoid H of relay 66 which extends from contact member 80a of the timeedelay device through contact members 13, 13a and 1311, conductor 88, solenoid H and adjustable resistor 81 to line L2.

When valve 15 of relay device 66 is opened,

pressure is transmitted to the actuating mechanisms of valves l8 and 69.

The operating mechanism of valve 69 is so designed that it will open the valve at a lower value of operating pressure than required by mechanism 61 to open valve ll] so that steam is turned on for nozzles 6 before valve In is opened. In order to delay further the opening of valve ID, a time-delay device 9|, such as a needle valve, may be utilized in pressure line leading from valve 15 to delay the building up of the operating pressure in operating mechanism 61.

In order to insure that valve It] will close before valve 69 closes, a check valve 92 is connected in parallel with needle valve 9| and operates to exhaust quickly the operating pressure from operating mechanism 6! when valve 15 is closed in response to deenergization of solenoid l I.

The operating mechanisms of valves l9 and 68 will be described later herein.

After valves I 0 and 69 have beenopened as above described, automatic booster 5 will continue to function and remain in operation until the temperature of the chilled water in flash tank I is lowered to a predetermined low value at which time contact member 63 engages contact mem- 93, to the adjustable resistor 81.. The connection of conductor 93 to the variable resistor is at such a point that solenoid H is substantially shortcircuited. As soon as this solenoid is deenergized its armature drops down closing valve l5, opening the holding circuit therefor and closing contact members 14, 14a and 141, which will allow the solenoid of valve 58 to be reenergized when contact members 63 and 64 of thethermostat reengage.

Variable resistor 81 has such a value of resistance that when the bridging circuit or deenergizing circuit for solenoid H is established by the thermostat a short circuit across lines L1 and L2 cannot occur.

If it is desired to provide for turning booster 5 on or off independently of the thermostat 62 a double-throw switch 94 may be provided. Closing contact members 95 and 96 thereof, accomplishes the same function as when contact members 63 and 64 of the thermostat are in engagement, the closing of contact members 95 and 91 establishes the same bridging circuit that is established by contact members 63 and 65 of the thermostat. When contact member 63 is in neutral position as shown, booster 5 will remai in operation.

In the operation of the system shown inFig. 3 and as above described, it will be observed that when valve 58 opens to allowtank 57 to be charged with air, regulator I! will close its escapement valve 26 whereby the pressure in the diaphragm housing 2! is exhausted to atmosphere, allowing valve l5 to open wide so that the maximum amount of cooling water is delivered to the condenser. Because of time-delay device H! the water-control valve l5 will remain in its wideopen position for a period of time, depending upon the time required for the time-delay device to energize initially solenoid 7|. Valve l5 will gradually move toward its normalposition as the pressur in tank 51 leaks out through its jet 56 which insures that ample cooling water will be supplied the condenser before and at the time booster 5 is turned on. After booster 5 has been in operation for a predetermined length of time and after the pressure has been exhausted from tank 51, regulator I! will resume normal operation and control valve l5 inaccordance with the difierence between the pressurein condenser 2 and flash tank I and thereby maintain a constant difference between the condenser pressure P2 and the flash tank pressure P1.

The operating mechanisms for valves I 0 and 69 are shown in Fig. 3a and comprise a valve stem a having at the top thereof a thrust plate 12 against which a flexible diaphragm c bears. This diaphragm is enclosed in a pressure-tight housing 5 d. A compression spring 6 disposed about the valve stem and nested in a socket 7 carried by the valve body of either valve II] or valve 69 is adjusted to the proper degree of tension by means of a thrust plate 9' and nut h. Springs e tend to move valve stems upwardly and to close the valves. Pressure for opening these valves is received from valve 15 through pipes 98 and 96" respectively.

The tension of springs e of the operating mechanism of valve In may be adjusted so that a higher pressure is required to open this valve than would be required to open valve 69. To delay further the opening of valve ID, a needlevalve 9| may be connected in line 96 so that the operating pressure required to open the valve will not build up in the diaphragm housing until after the required operating pressure has been built upin the diaphragmhousing of the operating mech anism of valve 69. To insure that valve I will close before valve 69 closes, a check valve 92 may be connected in parallel with needle valve 9|. This check valve will allow the operating pressure to exhaust rapidly from the diaphragm housing through valve I to the atmosphere when valve I5 is closed, but prevents air supply from passing around needle valve 9| when the operating pressure is building up.

If it is desired to delay the closing of steamcontrol valve 69 sufliciently to insure that valve I0 will be closed before the steam valve closes, a needle valve 9's. may be connected in pipe line 90' and a check valve 92b may be connected in parallel with this needle valve. The check valve acts to allow the pressure to build up quickly in the operating mechanism for valve 69 but it will not allow the pressure medium to escape except through needle valve 9's. when the valve 15 is closed, thereby delaying the closing of steam valve 69 until after valve l0 has closed.

Where operating conditions are such that the automatic booster or boosters are not required except for peak load purposes, such as occur regularly during certain periods or hours of a twenty-four-hour day, a controller may be employed that operates to disconnect thermostat contact member, 63 from line L; during the off peak periods and connect the same thereto during the peak periods. Such a device is indicated diagrammatically at 99 and commonly referred to in this art as a cyclic controller.

The system shown in Fig. 4 is of the same type as shown and described in Fig. 3 with the addition of auxiliary control mechanism for controlling the operation of the condenser cooling Water regulating valve I5. Such parts of the system of Fig. 4 as are similar in structure and operation with the system of Fig. 3 will be given similar reference characters.

The system of Fig. 4 is designed to provide the condenser with the maximum available amount of cooling water whenever and so long as the temperature of the chilled water in tank I remains above a predetermined valve. Such a control acts to insure adequate cooling water during breaking of boosters. There are times when a booster may stop functioning, in which. case steam continues to flow to the condenser but novapor is transferred thereby from the flash tank to the condenser. This results in warm chilled water. With the use of auxiliary control, the water-control valve I5 will be opened wide whenever the temperature of the chilled water rises above a certain value and full flow of cooling water through the condenser will be maintained until the pressure in the condenser is reduced to the point where the boosters start to function again as. compressors. After the boosters have been restored to normal operation and have functioned long enough, the temperature of the water in the'tank I will be lowered to the proper value at which time regulation of the water-control valve is taken over by regulator IT.

The auxiliary control mechanism referred to above is illustrated as comprising a thermostat I00,'a relay' IOI controlled by the thermostat and a valve I02 connected in pressure line 43 and operated by relay IOI.

When-relay MI is deenergized, valve I02 allows free communication between escapement valve 26' 'ofregulator I I and the diaphragm housing of valve I5, 'but when the relay is energized valve I02 closes 01f such communication and exhausts the pressure medium from this diaphragm mechanism to the atmosphere, allowing valve I5 to open wide. V

The coil of relay I9! is energized when contact members I04 and I05 of thermostat I00 are in "engagement, the coil being thereby connected across lines L1 and L2. When energized its armature I06 is pulled upwardly and turns a lever I071 in such direction as to close the inlet port of valve I02 and open, its exhaust port. As soon as the temperature of water in tank I drops to a predetermined value,,contact members I04 and I05 open, thereby deenergizing relay I 0| and causing valve I02 to close its'exhaust port and to open its inlet port.

In Fig. 5, a modified form of automatic control system is illustrated but such parts and apparatus as are similar to those of Figs. 1, 3 and 4 will be. given the same ref rence characters With. primes affixed thereto. As will be apparent by inspection of Fig. 5, solenoid valve 58, tank 51, and cup 55 and jet 56 have been omitted and a time-delay relay I09 and a relay valve I I0 have been substituted therefor.

.Relay valve I I is under the control of thermostat 62' and is energized when contact members 63 and 94 are in engagement, and is deenergized in response to the energization of relay device 95'. Relay .66 is energized when timedelay relay I09 closes. During the time required for relay I09 toclose, valve I5 ,is open wide so that condenser 2 is supplied with excess cooling water before booster 5' is turned on. The booster is turned off when contact members 63 and 65 are in engagement by establishing a bridging or deenergizing circuit forsolenoid II of relay device 66 in the manner already described in connection with Fig. 3.

Time-delay relay I09 comprises a Solenoid having a core associated therewith and .carries a moveable contact member I II adapted to engage stationary contact members H2 and H3. An extension of the core is connected to a dash-pot I I4 which acts to delay closing of relay I 09 when it is energized. Device IIO comprises a solenoid H5, a moveable core H6 having a contact member III associated therewith disposed to engage stationary contact members H8 and H9 and a valve I20 similar to valve I02 and which is operated by the core through a lever I2I. When the solenoid is energized valve I20 is moved to its closed position whereby the diaphragm chamber 2| is opened to exhaust through the valve to the atmosphere. This causes valve I5 to open wide.

When the chilled water temperature reaches a value at which contact members 63' and 64 are in engagement a circuit is established for energizing the solenoid of relay I I0 that extends from line L1 through contact members 63' and 64, conductor 84, contact members 143, and Mb, conductor I22, through solenoid H5 and conductor I 23 to line Lg. Upon the closing'of relay I I0 contact members I I1, I I8 and I I9 thereof are closed, whereby a circuit is established for energizing the solenoid of relay I09 that extends from line L1 through the solenoid thereof, conductor I24, contact members H1, H9 and H9 of device H0 and conductor I23 to line L2. After a predetermined length of time, relay I 09 closes, whereby an energizing circuit is established for coil'lI' of relay 66'. This circuit extends from line L; through contact members III, 2' and H3 of relay I09, coilII', resistor 81' to line L2. Upon the energization of coil II its core IZis moved upwardly, whereby contact member I4 is moved out of engagement with contact members 14s and MD and contact member I3 is moved into engagement with contact members 13a. and 13b, whereby a holding circuit is established for coil II. This holding circuit enables coil ii. to remain energized after relay I 09 is deenergized in response to the opening of relay I III whichoccurs when contact member It moves out of engagement with contact members Ma and Mn. Upon the energization of relay coil II operating pressure is transmittedto the acclosed in Fig.5 is illustrated, whereby time-delay device H39 and the contact'm embers of relay III) may be omitted. Coil I55. which closes Valve I29 in response to thermostat 62, engaging its contact members 53' and B4 to efiect a release of operating pressure from the diaphragm housing 2 I for condenser cooling water control valve Iii", would be connected in the circuit in the same manner as the coil of relay i It is connected (see Fig. 5). In other words, terminal I26 of this coil would be connected to line L2 and terminal I21 thereof would be connected to a contact corresponding to contact member Mb of relay 66'. A pressure-type of time-delay device I23 may be employed to replacetime-delay device I69 and adjusted to operate a predetermined length of time after the pressure in diaphragm housing 2i" has been exhausted to the atmosphere. The time-delay device comprises a pressure-tight housing I29 in which a bellows I39 is disclosed, and having connected thereto a plunger I3I carrying a moveable contact member I32 disposed to engage stationary contact members I 33 and I34. Housing I29 is connected by a pipe I 35 to the pipe which serves the diaphragm housing 2 I A time-delay member I36, such as a needle valve, may be con nected in pipe I35 to regulate the time element of device I28. When normal pressure is supplied to housing 2 I", device I28 would be in its open position, but when valve I2Il' is closed by relay H5 then air would leak out from housing I 29 through needle valve I 35 and valve I20 to the atmosphere,

the needle valve controlling the time at which contact members I32, I33 and I3 1 are closed. Stationary contact member I3 of device I28 would be connected to conductor 86 leading to coil winding II and contact member I33 thereof would be connected to line L1 and to contact member 73a of relay 6t.

Where condenser 2 is supplied with cooling water that is circulated through a cooling tower where it is cooled and returned to the condenser, a control system such as shown in Fig. 6 may be utilized. The system shownin Fig. 6 deals only with the control of the cooling water of the condenser and auxiliaries associated with the refrigerating apparatus or parts thereof, such as the cooling tower. It will be understood, however, that the automatic control system herein disclosed may be utilized in connection wtih this system for obtaining automatic control of one or more boosters.

In the system shown in Fig. 6, water is pumped from the cooling tower through the condenser and then back into the cooling tower I40. A watercontrol valve MI is disposed in the water supply line and is under the control of a regulator IIz, such as has already been described herein. This regulator responds to the difference between the absolute pressure in the condenser and in the flash tank and adjusts the water-control valve in such manner that a substantially constant difference between P2 and P1 is maintained.

There may be times when the capacity of the cooling tower is exceeded in which case the rate of cooling of the water in the cooling tower could be increased by means of a fan Hi2 blowing air through the cooling tower. Such a fan could be driven by an electric motor I43 or the cooling tower water could be supplemented by an auxiliai'y supply of water, such as available city water, or both.

The supply of auxiliary water is indicated by a pipe line I44 in which a pressure-operated valve M5 is disposed and which would be normally closed so long as the temperature of the Water discharging from the cooling tower was below a predetermined value. As soon as the temperature of this water rises above such predetermined value, a temperature-responsive member I46 would actuate thepressure mechanism controlling this valve and cause the auxiliary watersupply to matic starting of motor I43. This pressure-operated relay could be operated also from the temperature of the cooling water to control automatic starting or stopping of the cooling tower fan.

It will be apparent from the disclosure of the invention of this application that various modifioations and changes may be made in the dc tails of construction and arrangement of parts without departing from either the spirit or scope thereof. It is desired, therefore, that only such limitations shall be placed on the invention as are imposed by the prior art and the appended claims.

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

1. A control system for refrigerating apparatus of the type comprising a flash tank, a steam condenser provided witha supply of cooling water, and one or more steam actuated boosters or compressors that discharge steam and Water vapor evacuated from the flash tank into the condenser, water in the flash tank being cooled by the evactor action of said boosters, said control system comprising a regulator responsive to the dilference between the flash tank and condenser steam-space pressures, and means controlled by said regulator for so regulating the supply of cooling water to the condenser that a substantially constant difference between said condenser and flash tank pressures is maintained.

with a plurality of boosters atleast one of which is arranged to be turned on and off automatical- 1y, said control system comprising a regulator responsive to pressure conditions in the flash tank and the steam condenser for regulating the rate of supply of cooling water to the condenser to maintain a substantially constant differential therebetween, means responsive to the temperature of the chilled water of the flash tank for starting said automatic booster when said temperature reaches a predetermined high value and stopping it when said temperature reaches a predetermined low value, and means for automatically temporarily increasing the supply of cooling water to the condenser and delaying the starting of said automatic booster for a predetermined length of time after said temporary increase in cooling water has been effected.

4. A control system according to claim 3 characterized by the fact that means are provided for increasing the supply of condenser cooling water independently of the requirements called for by said condenser and flash tank pressure differential in response to the temperature of the water in the flash tank rising above a predetermined value.

5. A control system for cooling apparatus of the type including a flash tank, a water cooled condenser and a plurality of steam jet compressors connected to said condenser and flash tank, each of said compressors being provided with a valve for shutting off communication between the flash tank, and both the stem supply and the condenser, said system comprising a regulator responsive to the flash tank and the condenser steam-space pressures for so regulating the supply of cooling water to the condenser that a predetermined difierence between. said pressures is maintained, means for turning on or ofi one or more of said compressors in accordance with the load requirements imposed on the flash tank, means operative in advance of the turning on of a compressor for so loading said regulator that the water supply to the condenser is substantially increased before said compressor begins to function, and means operative after a predetermined time interval for rendering said regulator loading means inoperative and causing said regulator to regulate the condenser cooling water in accordance with said flash tank and condenser-steam space pressures.

6. A control system for cooling apparatus of the type including a flash tank, a water cooled condenser and a plurality of steam jet compressors connected to said condenser and flash tank, each of said compressors being provided with a first valve for turning on or shutting 011 the steam supply thereto, and a second valve between the flash tank and the jets thereof, said system comprising a regulator responsive to the flash tank and the condenser steam-space pressures for so regulating the supply of cooling water to the condenser that a predetermined difierence be tween said pressures is maintained, means for opening said flrst and second valves in sequence to turn said compressor on, means operative in advance of the turning on of a compressor for so loading said regulator that the water supply to the condenser is substantially increased before said compressor begins to function, and means operative after a predetermined time interval for rendering said regulator loading means inoperative and causing said regulator to regulate the condenser cooling water in accordance with said flash tank and condenser-steam space pressures.

'7. A control system according to claim 6 characterized by the fact that means are provided for closing the second and first valves in sequence, but causing the second valve to close ahead of the first valve.

ALFRED A. M ARKSON.

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