US1906702A - Water level control for boilers - Google Patents

Description

May 2p 1933 l. E. MCCABE 1,906,702

WATER LEVER CONTROL FOR BOILER-S Filed June 29, 1931 5 Sheets-Sheer?l l :LE su?" ABW l TTORNEY May 2, 1933.

l. E. MCCABE WATER LEVER CONTROL FOR BQILERS Filed June 29, 1951 s sheets-sheet 2 INVENTOR IRA E. NCCABE I ATTORNEY May 2, 1933- l. E. MccABE 1,906,702

WATER LEVER CONTROL FOR BOILEFS Filed June 29, .1.931 5 Sheets-Sheet aNvENToR gm E. y1@ @ABE TTOR N EY Patented May 2, 193,3

UNITED STATES PATENT ori-Ica IRA E. MCCABE, F CHICGO, ILLI 01S 'WATER LEVEL GNTROI FOB BILMS Application tiled June 2% 5 as to operate without the use of glands orI packing.

ln steam boilers of any character, it is necessary that the water be maintained at approximately the same level within the boillo' er and various devices have been employed to automatically operate a pump to. supply water to the boiler when the .level within theboiler lowers to such a degree as to approach j the danger point. Heretofore controls of this character have employed a packing about a shaft operating the control mechanism and it has been found that particularly in the case of high pressure boilers the packing soon ibecomes ineffective. It is an object ofthis invention to provide a water level control of such construction that it will positively and continually operate without the use of any packing. It is a further object of this invention to provide `a water level control such as above described which may be connected to operate t an alarm when the water in the boiler reaches a low danger'level; may beconnected to operate a boiler feed pump when the water level v reaches a low danger point and thereby supply water to the boiler; mav be connected vin' an electrically operated fluid fuel burner control system whereby the fluid fuel burner motor circuit may be broken upon the water level reaching a low danger point; and may be A employed in an electrically operated and controlled vfluid fuel burner control system whereby excessive pressure within the boiler 40. will `break the burner motor circuit and in which thelow level of the water approaching the danger point will not only operate the boiler feed pump but also break the burner ,-motor'circuit until the feed pump has raised I the level of the water within the boiler, where.-

931. Serial No. 5Q7D581.

upon the burner motor circuit will be closed andthe feed pump circuit broken.

Figure l is a perspective view of a com`= mercial boiler illustrating the application of this invention as connected to operate a motor driven feed water pump.

Figure 2 is an enlarged det-ail view in front elevation of the oat casing, illustrating the float operated mechanisms in diagram.

Figure 3 is an enlarged detail view partly in vertical section and partly in side elevation of the mechanism operated by the float.

Figure 4 is a view in end elevation of Figure 3 with the cover thereof shown in section and with parts broken away.

Figurey 5 is a view similar to Figure 2, partly in section illustrating the application of this invention in connectiony with a low water level alarm.

Figure 6 is a view in front elevation, partly in section and with parts removed, illustrating an application of this invention combining a pressure control, a feed water pump control and a fluid fuel rburner motor control combined in the control system of an electrically operated iluid fuel burner heating system, the wiring of which is indicated in diagram. v

The embodiment of this invention as illustrated in Figures 1, 2, 3 and 4 illustrate its application to a commercial steam boiler installation B and applied to control the operation of a` motor M operating a feedl water pump P connected to feed water into the boiler B.

The float valve casing C is connected to the interior of the boiler by'means of pipes- 1 and. 2 which enter the boiler above Yand below the normal water line therein and so; position the casing that the normal level of the water within the boiler is approximately opposite the horizontal center of the casing. A float F is mounted within the casing provided with an' upwardly projecting stem 3 l adapted to travel in a vertical direction within a tube 4 of non-magnetic material interposed between the top of the-casing C and the pipe 2 leading to the interior of the boiler above its normal water level.

An instrument casing 5 is supported about the non-magnetic tube 4 and mounts a solenoid coil 6 about; the lower vportion of the non-magnetic tube 4. The upper extremity of the stem 3 supports a core 7 adapted to be reciprocated as the float rises and falls in accordance with water level of the boiler causing the core 7 to enter or be withdrawn from within the surrounding coil 6.

Another solenoid coil is mounted within the casing 5 surrounding a reciprocated core p9 the lower extremity of which is pivotally attached to the free end ofa pivoted'arni 10,

which in turn supports and carries with it a mercury tube switch 11 of commercial construction. Three hinding posts 12, 13, and 14 are also mounted within the casing 5. The coils-6 and- 8 are connected in series with the binding posts `13 and 14,'respectively, and

the terminalsof mercury tube switch'11 are connected to the binding posts 12 and 13, respectivel The windings of the coils 6 and 8 are preferably of material that will allow a constant flow of current, irrespective of the temperature of the surrounding atmosphere. and are of a sufiicient number of turns to operate as solenoids irrespective of the normal variations in the commercial current.

The parts are so arranged that when the water level within tne boiler is below normal, the float F will withdraw the core 7 from within the windings of the coil 6 reducing the reactance thereof, so that more current will pass from binding post 13 through coils 6 and 8 to binding post 14, thereby energizing the, solenoid 8 to draw upward its core 9 and close switch 11 to connect the incoming current from binding post 1 3 through binding post 12 to operate the motor .M of the pump P to supply water to the boil( When the level of the water in the boiler reaches the normal level it will cause the float F to enter the core 7 within the windings 6 increasing the reactance thereof sufficiently to deenergize the solenoid 8 to drop its core 9 andthereby open switch 11 to break thecircuit tothe pump motor;

The construction above described illustrates an application of this invention to con'- reached. and this operation is consummated without the use of glands or packing inte/rposedbet'ween the float and operating mechanism, Figure 5 illustrates an application of this invention as a low water level alarm, in which the parts of the operating mechanism are the same as heretofore described and bear corresponding reference numbers. However, in this construction, the core 7 is carried upon the arm 3 depending from the ioat F so .that while the water level is at normal, the

switch 11 is held in open position. and when the level descends and approaches the danger point, the core 7 enters within the solenoid coil 6, reducing the current passing through the-coil 8 so that the switch 11 rotates in a downward direction and closes the circuit to the alarm. When water is fed into the boiler and the level rises, the core 7 is withdrawn and the switch 11 will open.

Figure 6 illustrates the application of this invention to a. domestic fluid fuel burner, such as employed in domestic'heating plants of the steam heating type. In this application the parts above described are indicated by the corresponding reference numerals and an additional control box 15 is supported upon atubular member 16 of non-magnetic material interposed between the top of the casing C and the pipe 2 leading to the interior of the boiler above the water level and the float F is provided with an upwardly extending stem 17 mounting a core 18 adapted to enter and be withdrawn from within the solenoid coil 19 which is connected in lseries with the solenoid coil 20 through binding posts 21 and 23. The core 24 of the solenoid 20 is pivotally connected to the free end of the pivoted lever 25 carrying a. merlcury tube switch 26, the terminals of which are connected to binding posts 22 and 40, reY spectively. The mechanism within casing 15 is of simil' r constructionto that within the casing 5.

In addition the casing C mounts a support 27 having communication with the interior of the casing C and mounts at its outer end a pressure actuated switch mechanism of commercial design within a casing 28. The pressure actuatedV switch mechanism within casing 28 is preferably of the type illustrated in the McCabe Patent No. 1,734,016, October 29, 1929, which includes a Bourdon tube, the interior of which -communicates through a stem 29 with the bottom of a receptacle 30 depending from the support 27 and communicating through aperture 31 to the interior of the casing C.

As the position of the float F changes with the rise and fall of the water level, the effect of the cores 7 and 18 upon the operation of their respective switch operating mechanism issuch that the corel 18 may enter and be withdrawn to open and close the feed pump circuit -through switch 26 without the core 7 doing likewise to the ,burner motor circuit as long as the float is maintained between the normal levels` indicatedl on Figure 6 tj' the dotted lines, A and B. These levels are the operating points or rather govern the supply of water desired during the period of combustion and the lower of these levels is vslightly above the low water line of the boiler.

However, in the event .the water should de-I crease to the low water line, the core 7 would enter the coil 6 resulting in the core 9 being released from the solenoid 8 and the opening of the circuit through the mercury switch l1, stopping the burner motor` and also breaking the circuit through the solenoid which releases the core 24 to open the circuit to the feed pump P, as indicated upon the wiring diagram. y By making the operation of the feed pump dependent on rthe burner motor switch ll being closed it is possible to prevent the pumping of an unlimited amount of water into a boiler Where the float becomes defective and sinks. e Referring to the Wiring diagram, the cuirent from the commercial source of electricity passes through wire 3Q and divides. A part passes through'wire 33 to the pressure switch 28 continuing through the mercury switch 39a therein and bylead 34 to binding post 13 in the lower casing 5. From binding post 13 a part ot the current passes through the coil 6 and the solenoid 3 to binding post lllA and then through lead to the return lead 36 to the commercial line., 'lhe other parteic the current troni post i3 passes through the mercury tube "il, when closed, to binding post l2 from which point a circuit is compl'eted'throughthe burner motor M and another completed through wire 3? to bindingl post 23 in the upper casing l5 and then through the coil i9 and solenoid 2O to binding post 2l and then through wire 38 it returns by lead 3G to the commercial line.

The other part oi the current from. the commercial source of electricity in entering through lead 32 passes through `wire to binding post 22 inthe upper casing. From thin'dingpost 22 it 'passes through the mercury tube switch 26 to binding post thence through wire-ll to the reisde/eter pump and then through wires i2 and 35 'to the return lead 36 to the commercial. line. ls shown' inY ltiigure @,fthe heat i? dropped, as the water reaches its lowest normal "level, to place the core l within the coil tl thereby increasing the reactance to reduce the current passing throughthe solenoid 3 which releasesthe core 9 to dropand throw the mercury tube ll to theopen position ls stated before the incoming current from f the commercial source in passing through 'fet the pressure 'switch Q8 and wire enters the 'casing 5 by binding post 13 and with the switch l1 open the circuit isbroken to the burner motor M and through wire 37 and coil 19 to thesolenoid 2@ which will thenreleaseits core 24 to drop and open the mercury tube switch 26 stopping the feed pump motor,

As the causes resulting in the float sink ing to make the burner motor and pump inoperative are remedied and the water Ahas been returned to its low operating level B-B the core l will then here have been withdrawn enough to Lallow the lull vcurrent to pass through the solenoid 8 which draws within it the core 9, thereby closing the mercury switch 1l, Theretore, the current in ventering the casing 5 passes trom.'A the binding post 13 through switch ll and binding post l2 and then to the burner motor M and through wire 35 to the return lead 36.

rlhe current also passes :trom binding postY l2 through the wire 37 to binding post 23 in the upper casing and from there the full current passes through coil 19 to solenoid 20 and by wire 38 to the return lead 36. The full current through the solenoid 20 lifts the core 2l to close the mercury switch 26. The current then enteringI the casing l5 through wire 39 to binding post 22' passes therefrom 'through switch 26 to binding post 40 and core to fall and open the switch 2h, thereby E stopping the feed pump motoru lt is also to ne noted that in the event el? excessive steam'pressure tending to exceed the safe Working limits o boiler, the

switch 39E in the pressure switch casing 2S i will be opened to break the circuit to meru cury switch ll, thereby rendering the burner motor and feed pump inoperative until the pressure is decreased.

also should be notedthat should the 'f' tloat sink through causes other than that due to normal changes in water levehin all casesy shown, the equipment controlled by the switches is rendered inoperative, excepting, oil course Vin the case oil Figure 5, the alarm control, Whose function itis to indicate such conditions. f

f W hat l claim is:

Ai boiler water level 'controlled electric5 switch, including float chamber @inmuni-- cating with the interior of the boiler above and belou7 the normal water level therein, a

iioat within the chamber, a non-magnetic connection leadingY from the chamber forming one or the said cmmunications, a solenoid winding about said non-magnetic con? nection, a solenoid core actuated by said dont mounted to be reciprocated within 'the liti non-magnetic connection and solenoid wiridf ing, an additional solenoid connected in series with the first .solenoid and source of electricity so wound that when the core is inserted within the first solenoid win the circuit impedance is increased therein 5 and decreases the current flow through the additional solenoidv decreasing the magnetic ull thereof, a reciprocating core mounted 1n the additional solenoid, an electric switch and means actuated by the reciprocation of 19 the core of the additional solenoid to operate said switch.

IRA E. Md'JABE.

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