US2304150A

US2304150A - Solution concentration system

Info

Publication number: US2304150A
Application number: US207795A
Authority: US
Inventors: Robert B P Crawford
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-05-13
Filing date: 1938-05-13
Publication date: 1942-12-08
Anticipated expiration: 1959-12-08

Description

D- 8,1942- R. B. P. RAwFoRD 2,304,150`

SOLUTION COCENTR'I:[ON` SYSTEM I I Filed May 15,1938 2 sheets-sheen 1 8s' 86 sa Inventor Gttorneg De@ 8, l942 R. B. P.- CRAWFORD SOLUTION CONCENTRATION ASYSTEM Filed May l5, 1938 2 Sheets-Sheet 2 ma@ i :inventor Ittomeg Patented Dec. 8, 1942 UNITED STATES "PATENT OFFICE 2,304,150 Y l f t f SONTTEM `13 IClaims.

This invention relatesto solution concentrating systems for chemical dehumidifying systems in general and more particularly to an automatic control system therefor to insure safe operation thereof.

The chemical dehumidifying system of this invention may utilize a hygroscopic fluid such as calcium chloride, lithium chloride or any other chemical having moisture absorbing characteristics and it may comprise a boiler for heating the hygroscopic uid to increase the concen' tration thereof, a first conduit for conducting hygroscopic fluid of relatively high concentration from the boiler to a dehumidifying unit provided with means for contacting the hygroscopic uid with the air to be dehumidied, a second conduit for conducting hygroscopic uid of relatively low concentration from the dehumidifying unit to a reservoir and a third conduit for conducting the fluid from the reservoir to the boiler;

An object of this invention is `to provide a means for obtaining counteriowheat exchange between the hygroscopic uid flowing through the first and second conduitswhereby the efficiency of the system is greatly increased.

Another object is to provide heating means in the first conduit to prevent solidiiication of the uid of relatively high concentration flowing through the rst conduit,

A further object is to provide means for maintaining at least a predetermined amount of uid in the,l reservoir so that the boiler may be at all times supplied with fluid.

Still another object is Vto provide means for decreasing the flow of fluid to ythe rreservoir if the level of fluid therein becomes excessively high. f

A further object is to provide means for maintaining the temperature of the fluid in the boiler at a substantially constant value by controlling the firing means of the boiler.

Another object is to cause agitation of the fluid in the boiler incase it tends to stratify. This maybe accomplished by controlling the agitation of the uid in accordance with the difference in temperature of the iiuid at diierent points Within the boiler.

Another object is to maintain the level of the fluid in the boiler at a substantially constant value by controlling the flow of iiuid from the reservoir to the boiler.

Still another object is to shut off the firing means for the boiler and supply uid to the reservoir andhenceto the boiler if the fluid `1eve1in the boter shou1d decrease to :1t-.predeter-v mined low value. y y

A further object is to supply air under pressurey to prevent, excessive turbulence of .the'fluidu iny the boiler. v

'Ihis invention also contemplates the combination of these various features into a composite control `arrangement to insure safe operation of a Vchemical dehumidifying system.

Other objects and advantages will become apparent to those skilled in theV art upon reference to the accompanying specification,v claims and drawings, in which Figure 1 is a diagrammatic illustration -of this.

invention with the control system applied there-v Figure 2 is a schematic Wiring diagram showing schematically .the construction. of thev various control instrumentsand the wiring connec- A is contained the hyg'roscopic fluid to be concen-v trated, and a firing chamber I2 vfor heating the hygroscopic uid in the shell II. The boiler may be fired-by means of la burner, such as a high-low oil burner. I3. Gases 'of combustion are withdrawn fromjthe boiler I0 by means of a flue or breech I4 extending to a stack, not shown.

' Fuel such as oil may be supplied to the burnerv I3 through' a pipe I5 under the control of a mo'- jtorized main valve IB. A branch pipe I'I extend ing to thev burner I3 is controlled by a manually adjusted throttle valver I8 and a branch pipe Il extending to the burner I3 may be controlled by a motorized valve 20. When the motorized main valve I6 is open, fuel is supplied to the burner I3 yand if the motorized valve 20 is closed the fuel passes through the manual valve I8 to provide a low ame, and if the motorized valve 20 is open, a high ame is provided.

Hygroscopic iluid of arelatively high concenfV tration, for example 50%, is Withdrawn from the shell II by a pump 23 through a conduit 22, aheat exchanger 24, a conduit 25, a cooler 26 andaconduit 21 toa sump 28 of a dehumidifying unit generally designated at 29. Preferably the pump 23 is maintained continuously in oper-l ation. ,The cooler 26 may be provided with an inlet 30 and an outlet 3l for a cooling fluid such as .Well-Water for cooling the hygroscopic uid beforeit passes to the sump 28 of the dehumidifying unit 29. Abranch conduit 25' may be utilized for supplying. hygroscopic fluid to other .a concentrator in dehumidifying units, not shown. A motorized valve 32 located in the conduit 21 may be utilized for controlling the supply of concentrated fluid to the dehumidifying unit.

The dehumidifying unit 29 may comprise a chamber 33 provided with an air inlet 34 and an air outlet 35. Air is drawn through the chamber 33 by means of a fan 36 and discharged by a conduit 31 to the space .or room to be conditioned. Located in the chamber 33 is a cooling coil 38 for cooling the air .passing through the chamber. This cooling coil may be provided with a cooling fluid in any suitable manner.

pump 39 withdraws hydroscopic fluid from the .I

sump 28 through a conduit 49 and discharges this hygroscopic fluid through a spray 4I so that the hygroscopic fluid is contacted by the air passing through the dehumidifying unit toabsorb moisture therefrom. As a result, the confy centration of the hygroscopic fluid is decreased to a predetermined low value such as 45%.

' This hygroscopic fluid of relatively low concentration passes from the sump 28 through an overflow connection 43, a conduit v44, the heat exchanger 24 and a conduit 43 to a vreservoir generally designated at 41.V

The temperature of the hygroscopic fluid of relatively high concentration passing through the conduit 22 from the boiler is relatively high and it is necessary that this temperature be reduced before the highly concentrated hygroscopic fluid is supplied to the dehumidifying unit 29. Also, the temperature of the less concentrated hygroscopic fluid returning from the de. humidifying unit 29 is of relatively low temperature and must be heated in the boiler Ill to drive off the moisture contained therein. The heat exchanger 24 causes counterflow heat exchange between the hygroscopic fluid of relatively high concentration and the hygroscopic uid of relatively low concentration, whereby the overall efficiency' of the system is increased.

The reservoir 41 may comprise a container 49 in which the hygroscopic fluid may be stored pref paratory to being supplied to the boiler I6. The container 49 is provided with a duct 5U leading to the breech I4. The container 49 is provided with an overflow passage 5I which empties into a sewer 52. It is possible that under certain eX- treme conditions such as failure of the controls, the reservoir 41 may become filled with hygroscopic fluid to an overflow point. and-instead of permitting this fluid from'passing out through the flue or breachjit is made to pass out through the overflow conduit 5I. Under these conditions suitable receptacles such as barrels or tanks 53 may be utilized for catching this overflow of hygroscopic fluid so that it willnot be Wasted.

A conduit 55 extending from the reservoir 41 to the shell I I of the boiler I0 supplies hygroscopic fluid from the reservoir 41 to the shell II. The supply of fluid is controlled by a motorized valve 56 and if the level of the reservoir 41 with respect to the boiler I0 is such that gravity flow is not sufficient for this purpose a pump 51 may be utilized.

A conduit 59 connected between the conduit 22 and the reservoir 41 may be utilized undercertain conditions for supplying highly concentrated fluid from the boiler I0 to the reservoir 41. This conduit 59 is controlled by a motorized valve 60. A conduit 6I extends between the boiler shell II and the reservoir 41 so that the steam and entrained fluid escaping from the boiler will pass through this conduit 6I into the reservoir 41 and the moisture will pass through the passage 59 into the breech or flue I4. The conduit 6I also serves to equalize the pressures between the boiler shell II and the reservoir 41. The conduit 59 is connected by a conduit 63 to the boiler shell II and this conduit is controlled by a motorized valve 64. When the valve 64 is open, circulation is permitted through the conduit 22, pump 23 and

conduits

59 and 63 to agitate cr stir up the fluid contained in the boiler shell II. This is an effective method for agitating the fluid in the boiler shell II to prevent stratification and consequent crystallization of the fluid therein.

A humidity responsive controller 65 responsive-to therelative humidity of the dehumidiiled air leaving the dehumidifying unit controls the valve 32 to regulate the amount of hygroscopic fluid of relatively high concentration delivered to the dehumidifying unit. f

A temperature responsive controller 66 connected by a capillary tube 61 -to a bulb 68 located inthe fluid' in the boiler shell II is utilized for controlling the operation of the fuel rvalves I6 and 20 to maintain a substantially constant temperature within the boiler shellI` Il. When the Atemperature is low the temperature controller 66 maintains both lfuelfvalves 20 and I6 open. to provide a high flame for the boiler. As the temperature increases the valve 20'is closed to provide a low flameand if the temperature increases to a predeterminedhigher value the valve I6 is closed to shut down the burner I3. Preferably the temperature controller 66 is so adjusted that it will maintain the temperature of the fluid in the boiler at substantially 215.

A differential temperature controller 10 is connected by a capillary tube 1I to a bulb 12 located in the upper portion of the fluid in the boiler and' is also connected by a capillary tube 13 to a bulb 14 located in the lower portion of the boiler. This differential temperature controller 19 therefore responds to the temperatures at two points in the fluid in the boiler and operates to open the Valve 64 when the temperature differential exceeds, say 5. This causes agitation'of the fluid inthe boiler and therefore prevents stratification and crystallization of the fluid in the boiler. Y

A liquid level controller 16 controls the valve 56 and the pump 51 to supply fluid to the boiler shell vI I from the reservoir 41 upon a decrease in level therein. In other'words, the liquid level controller 16 operates to maintain the level of the fluid in the boiler substantially constant.

A liquid level controller 11 connected to the lower portion of the reservoir 41 controls the valve 60 to admit fluid from the boiler I0 to the reservoir 41 when the level-of the fluid in the reservoir falls to a predetermined low value. Accordingly, the liquid level controller 11 operates to maintain at leastV a Ipredetermined amount of liquid in the reservoir 1'I1.v

Liquid level controller connected to the reservoir 41 in the upper-end thereof operates the valve 45 to close the valve 45, which prevents the supply of fluid to the reservoir 41 when the level therein reaches a predetermined high value. n other words, the liquid level controller 88 operates to shut olf the supply of fluid to the reservoir 41 to prevent overflow therefrom.

If the liquid level in the reservoir approaches the overflow conduit 5I, a liquid level controller 82 sounds an alarm 8| indicating that the level in the reservoir 41 is extremely high and that the system is not operating properly. When this alarm 8| is sounded the engineer on the job is notified of the fact that the system is not operlating properly and if he feels that the reservoir 41 may overflow he may place the containers 53 under the overflow conduit 5| to catch the fluid in case it overflows from the reservoir 41.

A second liquid level controller 83 connected to the boiler at a lower level operates to shut oifthe burner I3 and to open the valve 45. This provides a safety control for the boiler to shut oif'the burner when the level of the fluid there- 4:in gets too low and to open the valve 45 to supincrease in pressure differential the differential pressure controller 85 will pull in a relay 88 to energize heaters 80 in the heat exchanger 24 to heat up the hygroscopic iluidof relatively high concentration to prevent vthe crystallization or solidification of the uid in the heat exchanger 24. This is an extremely practical and sure method of insuring that the' hygroscopic fluid will not crystallize and solidify in the heat exchanger 24 during the starting up period or during periods when dehumidifying unit 29 `is shut down. It is found that in boilers Yof this type for concentrating a hygroscopic fluid that on occasions the fluid in the boiler becomes extremely turbulent and in order to reduce this lturbulence to prevent priming of the boiler, that is, the ow of fluid out of the boiler, I supply air under pressure to the surface of the iluid in the boiler. This has a marked effect on the turbulence of the fluid in the boiler. It is found that the application of air to the surface of the fluid in the boiler decreases the turbulence thereof to a minimum and acts as a carrier for the steam flowing through the conduit 6| reservoir 41, duct'50 and breech I4 to the stack, not shown. The air under pressure also has a tendency to pierce or break up the bubbles caused by boiling, and the breaking up of the bubbles in thisV manner materially decreases the bubbling effect and therefore materially decreases the turbulence of the fluid. This supplying of air is accomplished by means of a pipe 9| leading from some source of air under pressure, not shown, to a nozzle arrangement 92 located in the boiler above the level of the uid therein. The supply of air through the pipe 9| to the nozzle arrangement 92 may be controlled by a motorized valve S3' which may be graduatingly positioned by aresistance type controller 94 contacted by the fluid in the boiler. The iluid being a relatively good conductor of electricity will vary the resistance of the resistance type controller 94 which will graduatingly position the valve 03 in accordance with the amount of splashing or turbulence of the fluid to maintain the turbulence of the fluid at a minimum. If desired an on and olf type controller as distinguished from the modulating or proportioning type illustrated may be utilized to turn on the air supply if the turbulence of the iiuid becomesexcessive. Y

The particular manner in which thefvarious If the iluid coming from the boiler u controls illustrated in Figure lare connected together and operated is shown in Figure 2.

The temperature "responsive controller 66 is shown to comprise .'a bellows '|00 connected by the capillary tube 61 to the bulb 68. The bulb 68 contains a volatile fluid sothat the bellows |00 is expanded and contracted in accordance with variations in temperature affecting the bulb 63. `The bellows |00 operates a pivoted lever I0| against the action of a tension spring |02 to operate' switches '|03 and |04. -Upon an increase in temperature the switch I 03 is rst opened and then at`a` higher temperature the switch |04 is opened and likewise upon a decrease in temperature the switch |04 is first closed and then the switch |03 is closed. By adjusting the tension in the springY |02 the temperaturesetting of th controller 66 may be adjusted at will.

The liquid levelvcontroller v03 may comprise a lever |05 provided with a float |06 responding to the level Vof the liquid in the boiler shell I The lever |05 operates a double-ended mercury switch |01. When the level of the liquid in the boiler shell is normal the two right-hand electrodes are bridged by the mercury 'and the two left-hand electrodesv are vunbridged." When the liquid level in theA boiler shell becomes abnormally low the switch |01 is tilted to the opposite position to unbridge the right-hand elec-v trodes and bridge the left-hand electrodes.

Line wires leading from somesource of power, not shown, are designated at ||0'and I. Assume now that the level of the fluid in the boiler is normal and that the temperature thereof is low so as to cause both switches |03f and |04 to be closed.l A circuit, is then completed from the line wire ||0 through wire ||2, switch |03, wire I3, motorized Valve 20 and wire I|4 back to the other line wire Completion of this circuit causes opening of the `motorized valve^20. At this same time another circuit is completed from the line wire I0 through wire ||5, switch |04, wire IIB, switch |01, wire II1, motorized valve I6 and wire ||8 back to the other line wire |ll.

This circuitopens the 'motorized valve IB. yWith the two valves |6 and 20 open, the burner I3 is operating under high flame; Ify now the temperature of the fluid within the boiler increases so as to move the switches |03 and |04 to the positions shown in Figure 2, the circuit through the motorized valve 20.is broken to close the valve 20. As a result, the burner I3V is operating on low ame. If the temperature of the fluid becomes too high so as to open the switch |04 or if :the level of the uid inthe boiler shell decreases to an abnormally low value, the switches ingly, the burner I3 is controlled in accordance with' thetemperature of the fluid in the boiler shell andif the temperature should become too high or 'if the level of the fluid therein becomes too low the burner I3 is shut off.

The differential temperature controller generally designated at 10 may comprise a bellows |20 connected to the bulb 12 containing a volatile iiuidand a bellows |2| connected to the bulb 14 containinga volatile iiuid. `The bellows |20 and |2| are therefore operated in accordance with the temperature affecting their respective bulbs. The bellows |20 and |2| operate a pivoted lever |22 for operating al mercury switch |24. A

= spring |23 urges -the lever |22V ina clockwise direction so that the .temperature affecting the bulb 1,4 must increasea predetermined amount above the temperature aiecting the bulb 12 `be- `fore the lever '|22 is rotated in a counter-clockwise direction. For purposes of illustration, it is assumed that when the temperature affecting the bulb 14 becomes 5 more than the temperature affecting thebulb' 12 .the spring |23 is overcome to tilt the switch |24 to a closed position. By adjusting the tension'in the spring |23 the differential in temperatures at which the switch |24 is operated may be adjusted. at will. When the switch |24 is moved to a closed position as a result of the temperature affecting the bulb 14 being 5 above the temperature .affectingthe bulb 12, a circuit is completed from the line Wire through wire |25, switch |24, wire |26, motorized valve 64 and wire |21 back` to the other limewire Completion of this circuit opens the motorized valve 64 to cause agitation of the uid in the boiler shell in the manner pointed out above. As a result of this agitation, the temperature differential isfdecreased and the .switch |24 is moved to the open position as shown in Figure 2 and the valve 64 is closed. Accordingly, when stratification tends to take place in the boiler |0 so as to cause the temperature at the lower portion thereof to be more than the temperature at'the upper portion thereof, the valve 64 is opened to cause agitation of the fluid in the boiler to decrease to a minimum the stratiiication of the fluid.

The liquid level controller 16 is shown to comprise a pivoted lever |29 connected to a float |30 operated in response to variations in level Vof the iiuid in the boiler shell' ||.Y The lever |29 operates a mercury switch |3| so that when the level in the boiler decreases to a predetermined value the switch |3| is closed. When the switch |3| is closed a circuit is completed from the line wire ||0, through wires |32 and |33, switch |3|, wire |34, motorized valve 56 and wires |35 and |36 back to the other line wire Completion of this circuit opens the motorized valve 56 to supply fluid from the reservoir 41 to the Vboiler |0 to maintain the level of the fluid in the boiler at a substantially constant value. 'The pump 51 located in the conduit v55 may be connected in parallel with the motorized valve 56 by wires |31 and |38 so that when the valve |56 is opened the j pump 51 is operated. This insures the supply of fluid through the boiler shell if the gravity head is not suiiicient to supply the iiuid.

The liquid level controller 11 may comprise a pivoted lever |40 operated by a float |4| in response to the level of the uid 'in the reservoir 4'1. 'Ihe lever |40 operates a mercury switch |42 to a closed position when the level of the liquid in the reservoir 41 decreases to a predetermined value. Closure of the switch |42 completes a circuit from the line wire |I0 through wire |43, switch |42, wire |44, motorized valve 60 and wire |45 back to the other line wire Completion of this circuit opens the motorized valve to supply fluid from the boiler l0 to the reservoir 41 to insure that there will always be at least a predetermined amount of fluid in the reservoir 41 for supply to the boiler. 'When the level of the fluid in the reservoir 41 rises to the desired minimum value the switch |42 is opened and the motorized valve 60 is closed to stop the further supply of fluid.

The liquid level responsive controller 80 may comprise a pivoted lever |41 carrying a float |48 responsive to the level of the liquid in the reservet() voir 41. yThe lever|41 carries a mercury switch |49 which is normally maintained in the position shown in Figure 2 wherein the electrodes are bridged. With the parts in this position a circuit -is completed from the line wire I0 through wires |32, |50, |52 and |53, mercury switch |40, wires |54 and |55, motorized valve 45 and wires |56, |58 and |36 back to the other line wire Completion of this circuit maintains the motorized valve 45 open so that uid of relatively low concentration may be supplied to the reservoir 41. If the level of the fluid in the reservoir41 should become extremely high the switch |49 is tilted in a clockwise direction to unbridge the electrodes. Unbridging of the electrodes interrupts the circuit through the motorized valve 45 to close the same and interrupt the supply of -iluid to the reservoir 41.

The left-hand electrodes of the mercury switch |01 of the liquid level controller 83 are connected in parallel with the left-hand electrodes ofthe mercury switch |49 of the liquid level controller by means of wires |62 and |63 so that if the electrodes of theY mercury switch |49 are unbridged to normally have the valve 45 closed, the left-hand electrodes of the switch |01 of the liquid level controller 83 may open the valve 45 if the level of the fluid in the boiler |-0 should become dangerously low. In other words, the liquid level controller 60 may close off the valve 45 to prevent the further supply of fluid to the reservoir 41, but if the level of the liquid within the boiler i0 should decrease to a dangerously low value this valve 45 will be opened by the liquid level controller 83 regardless of whether the liquid level controller 80 demands that the valve 45 be closed.

'Ihe differential pressure controller generally designated at may comprise a bellows |65 connected by a pipe 86 to the conduit 22 and a bellows |66V connected by a pipe 81 to the conduit 25. The bellows |65 and |66 operate a pivoted lever |61 and a tension spring |68 urges this lever in a counter-clockwise direction. The lever |61 operates a mercury switch |69. The spring |68 operates against the bellows |65 so that when the pressure affecting the bellows |65 rises a predetermined amount above the pressure affecting the bellows |66 the mercury switch |69 is moved .to a closed position. By adjusting the tension in the spring |68 the differential pressure setting of the dierential pressure controller 85 may be varied at will. The switch |69 controls the relay generally designated at 88, and the relay 88 may comprise an operating coil |10 for moving a switch arm |11 with respect to a contact |12. When the operating coil |10 is energized, the switch arm |1| is moved into engagement with the contact |12 and when it is deenergized the switch arm |1| is moved out of engagement with the contact 12 by means of springs, gravity or other means, not shown.

When there is danger of the fluid of relatively high concentration passing through the heat exchange 24 crystallizing or solidifying, the differential pressure controller closes the switch |69 to complete an energizing circuit for the relay 88 which may be traced from the line wire ||0, through Wires |32, |50, |13, |14 and |15, switch |69, wire |16, operating coil |10 and wires |11, |18, |19, |58 and |36 back to the other line wire I I. Completion of this circuit energizes the relay 88 to move the switch arm |1| into engagement with the contact |12. Movement of the Iswitch arm |1| into engagement with the contact |12 completes a circuit from the line wire IIO,. through wires |32, |50, |13, I14 and |80, switch arm I1I, contact |12, wire |8I, heater elements 89 connected in parallel, and wires |82, |83, |18, |19, |58 and |36 back to the other line wire III. Completion of this circuit causes energization of the heater 89 to heat the fluid of a relatively high concentration passing through the heat exchanger 24 to insure that the fluid will'not crystallize or solidify in the heat exchanger. 24.. When the pressure differential. decreases the switch |69 is opened, the relay 88 is dropped out and the heaters 8 9 are deener'gizeds The liquid level controller 82 may comprisefa pivoted lever |90 operated by a iioat |92 'for oper ating a switch |93. When the level of the liquid in the reservoir 41 rises-to a value which indicates that the fluid in the reservoir-41 may over? ow through the conduit 5I, the oat |92V rises to close the mercury switch |93 to complete a circuit from the line wire lI I0 through wire |94, mercury switch |93, wire |95, alarm 8| and wire |96 back to the other line wire I I. Completion of this circuit operates the alarm 8I'to notify the engineer that the system is not operating properly and that there is danger of the fluid in the reservoir 41 overflowing.

The Valve 32 which controlsv the supply .o f hygroscopic uid of relatively high concentration to thedehumidifying unit-29 may be operated. by a proportioning motor of v.the type shown and described in Patent No. 2,028,110 granted to D. G. Taylor on January 14, 1936. proportioning motor is provided with'three l.cegmtrol terminals which are connected to a potentiemeterA resistance 200.and slider .controlled by =the hurnidii'fy'ire-v sponsive'contro1ler,6 5. The humidity responsive controller may comprise a lever: 2'02 for operating the slider. 20| with respect to the potentiometer resistance 200. The lever V202 isbiased'inone direction by lmeans of a spring203 andis posi-v tioned by a humidity responsive element 204. Power is supplied to the `proportioning motor from the line wires l0 and I I I ,by wires 20,5 andl 206. Upon an increase in relative humidity the slider 20| is moved to theright with respectI to the resistance element 200 and the vvalve 32 is moved toward an open position in an amount proportional to the amount of movement of the slider 20 l. Upon a decrease Ain relative humidity the slider 20| is moved to the left and the valve 32 is moved towards a closed position in proportion to the amount of lefthand movement of the slider 2'0 I Accordingly, the valve .32 is positioned in accordance with the relative humidityof the' air leaving the dehumidifying unit 29 toregulate the flow of concentrated hygroscopic uid to the dehumidifying unit to maintain the lrelative humidity of the air leaving the unit ata subtantially constant value. l

-The'valve-93 which regulates the supply of air tothe surface of, the liquid-in the. boiler shell I I .maybe operated by a rackf2|0fwhich in'ltrn operatedbya.v pinion 2| lf. mounted onfashaft 2|2. The shaft 2|2 is'opeatedV throughY a'reducf tion geartrain; 2I3 by motor rotors` 2|4 and 21I5. The'fmotor lrotorfslf l 4` and A2 I5 vare` provided. with iield windings. 2I6 fand .211 respectively. 'j The field windings 216 and 2I.1.are.lcntrol1ed'by`a switch-arm V2`I8 cooperating with` contacts 2I9 and220. ff When the switch arm 2| 8 is, moved into ,engagement with the contact .2| 9 a circuit 'is cdm- .pleted from --the line wire I I0` through wire ,.22 If,

switch'arm 2m, contact2|aw1re 2,22, eid wind;

.mgmt-andres 2?@ bis eine einer. .1.19 wie III.v EnergiZation of the field winding 2I6 in this manner causes movement of the valve' 93 towards an open position. When the switch army 2I8 is moved into engagement with the contact.

220 a circuit is completed from the line wire I l0,

through wire 22|, switch arm 2|8, contact 220,

wire 224, field winding 2I1 and wire22'3 back to the other line wire I| I. Energization of the. field winding 2I1 inthis manner moves the valve`93 towards a closed position.` When the switch arm 2|8 is midway between .the contacts 2|9 and 220 as Villustrated in Figure 2, neither field winding 216 or 2|1 is energized and therefore the valve `33 remains in the vposition at which it is.

Theswitch arm 218 is controlled byan armature 225 which'is operated by

relay coils

226 and 221. When the field winding 226 is more highlyl energized than the field winding 221 the switch arm 2 I8 is moved into engagement with the contact 2I9 to move the valve 93 towards an open position and when the ieldwinding 221 is more highly energized than the field winding `226 the switch arm 2I8 is moved intor engagementr with the contact 220 to move the valve 93 towards a closed position. When the relay coils 226 and 221 are equally energized the switcharm 2| 8 is maintained midway between the contacts 2 I 9 and 220 and therefore the valve 93 remains'stationary. Power may be supplied to the relay coils 226 and 221 by means of a step-down transformer 230 having a primary 23| connected across the wires |25 Vand |21 which are in turn connected across the line wires IIO and I|| and a secondary 232. v

vThe resistance type controller 94 may comprise a conductor 235 and a resistance element 236. The conductor 235 and the resistance element 23S are engaged bythe iiuid in the boiler shell I I, and since this fluid conductselectricity quite readily the conductor 235`and resistance element v 236 form a variable resistance .the adjustment of which depends upon how much of the resistance is engaged by the fluid inthe boiler shell. When the fluid becomes turbulent it engages more and more 'of the) resistance'236 to in effect decrease the resistance thereof. v

The shaft 2|24 of the motor which `operates the valve 93 operates a slider 238l with respect to a resistance element 239. The slider 238 assumes a 'position with respect to the resistance element 239' corresponding to the position of the valve 93.

As the Valve 93 is moved towards an 'open position" the slider 238 is moved downwardly and as theV valve 93 is moved towardsja closed position the slider 238 is moved upwardly.l The relay coil 221 is connected across the secondary 232 of the transformer 230 and has located in series therewith a variable resistance 240. The relay coil 226 is also connected across the secondary 232 and has located in series therewith the variable resistance 236 of the controller 94 ,and the variable resistancev 2 '39 of the motor operated valve.

VV'With the level of the liquid midway of the resistance 236 of the controller 94 and the valve 93 in a mid position, the resistance 240 is so a'djustedthat the energizations ofthe relay coils 2,26 and 221. are equal, whereupon the parts remain Istationary, in the position shown in Figure 2. Assume now that the level of the liquid due to turbulenceL rises, the resistance 236V is .de creased whereupon the relayv coil 2,26 becomes more highly energized than ,thef'relay coil 221. This causes movement of thejvalve 93 towards an open position 'and also' downward movement of the slider 238. When the'slider 238 has moved downwardly sufficiently far to increase the resistance in series with the coil 226, the

coils

226 and 221 become equally energized and the valve 93 is maintained in its newly adjusted position. Conversely, upon a lowering of the level due to a decrease in turbulence of the fluid,v the resistance' 236 is increased and the relay coil 221 then becomes more highly energized than the relay coil '226. This moves the switch arm 2I8 into engagement with the contact 220 to move the valve 93 towards a closed position and to cause upward movement of the slider 238. When the slider 238 has moved suiiiciently far upwardly to causeA the energization of the relay coils 226 and 221 to become equal, the switch arm 2I8 is moved to the position shown in Figure 2 and the valve 93 is maintained in its new position. Accordingly, the valve 93 is modulatingly or graduatingly positioned in direct accordance with the amount 4of 'turbulence of the fluid withinv the boiler shell l I. By graduatingly controlling the supply of air underpressure to the surface of the level of the liquid` in the boiler shell l'I, in this manner the turbulence of the liquid is maintained at a minimum at all times.

From the above it is seen that a complete control system for a chemical dehumidifying system is provided to maintain the concentration of the hygroscopic fluid flowing to the dehumidifying unit ata substantially constant value,` and at the same time to insure that the chemical dehumidifying system operates safely.

Although for purposes of illustration. one form of this invention has been disclosed, other forms thereof may become apparent to those skilled in the art upon reference to this disclosure, and therefore this invention is to be limited only by the scope of the appended claims and prior art.

I claim as my invention:

l. In a system utilizing a solution, the combination of, a boiler for heating the solution to increase' the concentration thereof, a first conduit for conducting solution` of' relatively high concentration from the boiler to a point of use, a reservoir for the solution, a second conduitr for conducting solution oi' relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler. heat exchanger means for causing counterow heat exchange between the solution passing through the rst and second conduitsl heating means for said heat exchanger means, and means responsive to the pressure diiferential of the solution of relatively high concentration ilowing through said heat exchanger `means for controlling said heating means. 2. In a system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a rst conduit for conducting solution` of relatively high 'concentration from the boiler to a point of use, a reservoir for the solution,v a second conduit for conducting solution of relatively low concentration to the reservoir, athird conduit for conducting the solution from thel reservoir to the boiler, a pump for forcing solution `through said Vthird conduit,r a fourth conduit 'for conducting solution from the boiler to the reservoir, andV means responsive to` thelevel of the solution in the reservoir for controlling the iiow of solution through the fburth'conduit.'

I 3.V In a systemyutilizing "a solution,l the combination oi,"a boiler' f 'or heating, 'the solutionfto 'increase the concentration thereof, anrst conduit` for conducting solution of relatively high concentration from the boiler to a point'of use, a reservoir for-the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a thirdA conduit for con-2 ductingr the solution from the reservoir to the' boiler, a pump for forcing'solution throughsaid third conduit, a fourth conduit for conductingsolution from the boiler to` ,theV reservoir,imeans responsive to a low solution level in thev reservoir for causing flow of solution through the. fourth conduit, and means, responsive to aL high solution level in the reservoirL for decreasing the flow of solution through the second conduit.: 1 K 4'. In asystem utilizing a solution, the combinationof', a boiler for heating' the solution to' increase the concentration thereof, a first conduit for conducting solution of relatively high concentration from vthe boiler to a point of use; a reservoir for the solution, a second conduit for conducting solution of relatively low concentra` tion to the reservoin, a third conduit for conducting the solution from the reservoir to the boiler, and meansresponsive to the level. of the solution in the boiler for controlling-,the flow ofv solution through the third conduit for maintaining saidlevel at a substantially constant value, means responsive to the level of the solution in the reservoir for decreasing the flow through the second conduit when said level reaches a predetermined high value, andA means responsive to a low level of solutionkin the boiler for increasing the ilow through the second conduit independently of said first named means.

5,.,In a. system utilizing a solution, the combination of, a` boiler for heating the solution'to increase thel concentration thereof, a first conduit for conducting solution of relatively high concentrationv from the boilerA to a point of use, a reservoir' for the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler, means responsive to the level' of: the solution in .the reservoir forV decreasing the now through the second conduit when said level reaches a predetermined high value, and means responsive to a low level of solution in the boiler for increasing the ow through the second conduit independently of said first named means.

6. 'In a system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a first conduit for. Vconducting solution of relatively hignconcentration. from the boiler to a.v point of use, a reservoir for the solution, a second conduit for conducting solution of relatively low concentration to the reservoirl a third conduit' for conducting the solution from the reservoir to the boiler, firing means for the boiler, means responsive to the temperature ofthe solutionl inthe boiler for controllingk the firing means, andy means responsive to apredetermined lowllevel of the solution'in the boiler' for deenergizing ,the tiring '7'.` In a system utilizing asoluti'onythe" combination of` agboiler iorheating the4 solution; to increase. the Vconcentration, thereof', a filrst 4conduit for conducting Ysolution, of relatively high concentration' from the boilerto a point, off-use, a reservoir' for the solution, a second conduit for conducting solution of relatively lowconcentrationl to. the. reservoir, a third conduitv lfor conductingfthe solution from thereservoir tothe boiler, firing means for the boiler, means responsive to a predetermined low level of the solution in the boiler for deenergizing the iiring means, means responsive to a predetermined high level of the solution in the reservoir for decreasing the now through the second conduit, and means responsive to a predetermined loW level of the solution in the boiler for increasing the ow through the second conduit independently of the level of the solution in the reservoir.

8. In a system utilizing a solution, the combination oi, a boiler for heating the solution to increase the concentration thereof, a rst conduit for conducting solution of relatively high concentration from the boiler to a point of use, a reservoir for the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler, ring means for the boiler, means responsive to a predetermined low level of the solution in the boiler for deenergizing the ring means, means responsive `to a predetermined high level of the solution in the reservoir for decreasing the flow through the second conduit, means responsive to a predetermined low level of the solution in the y boiler for increasing the oW through the second conduit independently of the level of the solution in the reservoir, and means responsive to the temperature of the solution in the boiler for controlling the firing means to maintain a substantially constant temperature thereof.

9. In a system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a rst conduit for conducting solution .of relatively high concentration from the boiler to a point of use, a reservoir for the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler, ring means for the boiler, means responsive to a predetermined low level of the solution in the boiler for deenergizing the firing means, and means responsive to the level of the solution in the boiler for controlling the flow of solution through the third conduit to maintain said level at a substantially constant value.

10. In a system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a first conr duit for conducting solution of relatively high concentration from the boiler to a point of use, a reservoir for the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler, iiring means for the boiler, means respon- -sive to a predetermined low level of the solution in the boiler for deenergizing the-firing means, means responsive to the level of the solution in the boiler for controlling the flow of solution through the third conduit to maintain said level at a substantially constant value, and means responsive to the temperature of the solution in the boiler for also controlling the firing means to maintain said temperature at a substantially constant value. p

11. In a system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a rst conduit for conducting solution of relatively high concentration from the boiler to a point of use, a reservoir for the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler, and a fourth conduit for conducting steam and entrained solution from said boiler to said reservoir where said solution may be separated from the steam and may return to said boiler;`

12. In a system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a rst conduit for conducting solution of relatively high concentration from the boiler to a point of use, a reservoir for the solution, a second conduit for conducting solution of relatively low concentration to the reservoir, a third conduit for conducting the solution from the reservoir to the boiler, a fourth conduit for conducting steam and entrained solution from said boiler to said reservoir where said solution may be separated from the steam and may return to said boiler, a combustion chamber adapted to contain a re for heating the solution in said boiler, a iiue for conducting the products of 4.combustion to the atmosphere, and a iifth conduit for conducting steam from said reservoir to said iiue.

13. In a. system utilizing a solution, the combination of, a boiler for heating the solution to increase the concentration thereof, a rst conduit for conducting solution of relatively high concentration from the boiler to a point of use,

a heat exchanger means for cooling the solution passing through said conduit, heating means for said heat exchange means, and means responsive to the pressure differential of the solution of relatively high concentration iiowing through said heat exchanger means for controlling said heating means.

ROBERT B. P. CRAWFORD.