US1904324A - Water control apparatus - Google Patents

Description

April 18, 1933. T. A PEEBLES Y 1,904,324

WATER CONTROL APPARATUS Filed July 7, 1928 INVENTOR. M 4- Ma 34 ATTORNEYS.

Patented Apr. 18, 1933 UNITED STATE rriro uns A. rErisLEs,

P TE T FF or MOUNT tEBAnonrE-NnsYLvAn A, ssIe oaro JOHN ivr, HOPWOOD, or DORMONT, PENNSYLVANIA WA ER Colman/APPARATUS v "Application filed July 1928. Serial No. 291,990,

This invention relatesto water control paratus and moreiparticularly to apparatus for controlling the delivery of feed water toboilersand the like." x

Various forms .of feed water regulators have-been andare now in use and generally include a'throttle' valve arrangement which is actuated in response to the water level in the associated boiler forcontrolling the flow of feedwater through the valve to the boiler. As the waterlevel in the boler rises the control valve .is graduallyclosed andasthewater levelfalls it is-gradually-opened. For the successful operation of such a valve, it has been found necessary to COlltIOLdH some way, the pressure drop across the valve. The pressure on the incoming sideof the valve must be suilioient to fo'rcethroughthe valve the maximum amount of waterlwhich the associated boiler will ever need. Obviously, in plants where the boiler ratings are very high-at times, this pressure must be consid erable. In commercialinstallations, for ob}.

' vious practical reasons, it is not possible to fit valves of this; type closely, with'the result that .for low ratings or approximately banked conditions of the boiler, the highdifrz ferentialpressure :necessary for maximum load is such that the leakage past the valve-is too high for the minimum demand of the boiler such, for example, as occurs. whenjthe load or demand for steam is suddenly thrown ofi'. from agivenzboiler. I 1 l ,4

Various devices and arrangements have been-utilized for the purposeof overcoming the above defects and objections, but suchdeviceshave been'themselves either impractical or unsatisfactory in their, mode of operation, especially in times of certain emergencies.

l An object of this invention is to provide an apparatus of the type set forth of im'- roved construction; and arrangement which will be free of the objections to. similar apparatusnow in use and known to me.

--A further object is to provide an appa-- ated; 1

ratus' of the'type set forth which will operate independently of thecombustion control system provided in connection with the associated boiler. I i

' A further object is to provide a feed water control system of simple'construction and arrangement, which will be relatively cheap to manufacture and install and at the same time rugged in construction and reliable in operation. 1 V.

' 'These and other objects which will heap parent to those skilled in this particular art are accomplishedby means 'of the invention illustrated in the accompanying, drawing which illustratesdiagrammatically a water control apparatus constructed in accordance with one embodiment of this invention.

In the particular embodiment of thisinvention which has'been'chosen for the purposes of illustration,the feed water supply line is provided with the usual throttle valve for controlling the rate of flow through the line to the associated boiler. Mechanism is provided for opening or closing the valve in accordance with the demand for feed waterin the usual manner. Mechanism is also providedfor controllingthe pressure differential across the throttle valve so that the pres sure on the inlet side thereofiisv varied in accordancev with the extent of opening of such valve, orvin accordance with the rating at which the'associatediboiler is being oper- As illustrated, this invention is shown in connectionwith a boiler drum 5' associated with any desired form or typeof boiler fur-.. nace 6' and provided with a feed water supply line 7 for supplying the feed water to the boiler. A throttle valve 8'isassociated with the supply line for controlling the rate of; flow therethrough and mechanism is provided for operating and controlling this valve in accordance with the water level in the boiler.

' As illustrated, this mechanism includes an mounted on a supporting bracket and arranged so that its upper end is located above the water level of the boiler and connected to the steam space thereof through piping 11, while the lower end thereof is located below the water level of the boiler and connected to the water space thereof by suitable piping 12. The lower end of the tube 9 is slidably supported on bracket 10, so that it may be movable with relation to the upper end thereof and is fastened to one end of one arm of a bell crank lever 13 by a pin 13'. Bell crank 13 may be pivotally mounted upon any desired support 14. The other arm of crank 13' is pivotally connected bya link 15 to one end of a throttle valve operating lever- 16 mounted upon a stationary pivot 17 and operatively connected to the valve stem 18 of the throttle valve. 1

It is apparent that the tube 9 will contain water to the same level as the level of the water in the associated boiler drum 5 and the upper part of the tube, above'the water level, will be filled with steam from the steam space of the drum; also, the water in the lower portion of the tube will be cooler than the steam in the upper portion thereof, with the result that the relative proportions of water and steam in the tube vary as the water level of the boiler drum risesrand falls.

As the water level falls, a greater proportion of steam enters the tube so thatthe temperature thereof is raised, causing the tube to expand whereby the length thereof is increased. This expansion results in such a movement of the bell crank lever .13 that the valve operating lever 16 is'raised, whereby the throttle valve 8 is opened to increase the flow of feed water to the boiler drum. As the water level in the boiler drum rises the proportion of water in the tube increases, cooling the latter and causing the throttle valve to close, thereby reducing the supply of feed water to the boiler.

Mechanism is provided for controlling-the pressure drop across the throttle valve, and this mechanism is so arranged as to increase the pressure of feed water on the inlet'side of the valve 8 in accordance with and in proportion to any increase in the extent of valve opening, and to decrease the-pressure on the inlet side of the valve in accordance with any decrease in the extent of valve opening:- As illustrated, this'inechanism includes a valve 19 having associated therewithoperating mechanism so arranged that the feed water is delivered to the throttle valve at the desired pressure. This mechanism is illustrated as including a pressure control valve. operating regulator 20 of any desired type, but preferably constructed and ar ranged as disclosed in vthe Hopwood Patent No. 1,371,243 of March 15, 1921. The pressure responsive element of this regulator may be connected to the feed water supply line at opposite sides of the throttle valve 8 so as to be responsive to the pressure in the feed water line at opposite sides of the valve. The vertically movable frame 22 of the regulator is connected by a link 23 and a pivoted lever 23 to the valve stem 24 of the pressure controlling valve 19. The counter weights 25 of the regulator are adjusted so as to maintain any desired differential in pressure, or in other words, any predetermined pressure drop across the throttle valve 8 so that, with the mechanism so far described, the pressure controlling valve 19 would be set so as to maintain a practically constant pressure drop across the throttle valve 8. However, mech= anism is associated with the regulator 20 so as to modify the effect of the counter weights 25 in accordance with variations in the extent of opening of the throttle valve so as to open This mechanism includes a metal-bellows.

26 connected by a slidable rod 27 to the center of a lever 28, one end of which is connected by a link 29 to the throttle valve operating lever 16, and the other end of which is con nected by a link 30 to a valve plug 31 mounted in a housing 32 having one port connected to a pressure line 33 for delivering .fluid pres sure from any desired source '(not shown), a second or exhaust port connected with an exhaust line 34 and a third port, adapted to be connected by the plug 31 to either of the first named ports and associated witha line 35 communicating with a line 36 leadirlg to the interior of the metal bellows 26 and with a second branch line 37 leading to the interior of a second metal bellows 38, the upper end of which is connected by a link 39 with the counter weight supporting lever 40 of the reg-- ulator 20, through a small lever 41 pivoted at 42. The valve plug 31 is so formed that the slightest movement thereof will connect the line'35 and branch lines 36 and 37 with either the high pressure line 33 or the exhaust line Assuming that the demand for steam is in-' creased, resulting in increased steam genera tion and the lowering of the water level '111 the boiler drum 5, the water level will also be lowered in the tube element 9,'increasing the temperature thereof so as to open the throttle valve 8 and increase the flow of feed water to the boiler. valve operating lever 16 and this, in turn, causes the lever 28 to be rotated in a counter clockwise direction as shown in the drawing,

This operation raises the throttle bellows 38 adding to the ellect of the counter weights and lowering the crosshead 22 of the regulator so as to open the pressure controlling valve 19, delivering the feed Water to the throttle valve 8 at a higher pressure and increasing the pressure drop thereacross. As the demand for steam decreases, and the water level in the boiler drum 5 raises,the

reverse operation'will occur and the closing of the throttle valve 8 will raise the valve plug 31, connecting the interior of the bellows 26 and the bellows 38 with the exhaust line S l, thus lowering the pressure therein which, in turn, causes the sliding rod 27 on the bellows 26 to be lowered, returning the valve plug 81 to normal and at the same time reducing the effect or" the bellows 38 on the regulator 20, resulting in a closing movement of the pressure control valve 19. 7

It will, of course, be readily understood that the feed water supply line 7 is associated with a pumping mechanism (not shown) which supplies the water to the pressure controlling valve 19 at a pressure sulhciently above the boiler pressure to insurethe maintenance of the required maximum difierential across the throttle valve 8 when the latter is fully open. 7

It will be apparent that the present invention provides a system for regulating feed water which operates independently of any associated combustion control system and which controls the pressure differential across the feed water valve in accordance with the flow of water to the boiler, or in other words, in accordance with the extent of opening of the valve As the load on the plant is increased. and there is a demand for additional feed water, the throttle va ve gradually opens and this, in turn, eilects a corresponding increase in the differential pressure, the latter reaching a maximum when the valve is wide open. An important features of this invention is the -fact that the position of the throttle valve determines the pressure drop across it.

Thus. if it were not for the bellows 38, and

lator 20 would operate upon the control valve 19 to maintain thepressure drop or differential across the throttle valve 8 at aconstant value. But, by reason of-the upper bellows 26 and the valve plug 31, each increment of rise of the valve stem 18 and consequent opening of throttle valve 8, is represented by a given increment of pressure, momentarily permitted by the plug valve 31 to enter from the pressure line 33 into the line 37 and bellows 28 and 38. This pressure increment, by reason of its simultaneous action upon the bellows 26, causes the lever 2'2 and thus, the point of pivot of the lever 28, to rise by a like, or if desirable, by a givenincre-ment.

The action of bellows 26, as above described, tends to allow only the pressure increment, representative of given rise ofthe valvestem 18, to vpassinto the line 37, and

when that increment has been sent-out, to im-' mediately raisethe pivot point of lever 28' and the associated plug-valve 31 sufiiciently to flclo'se oil the pressure flow from line33't0 v Theactionot bellows 38 tends to 'lessen the efiiectiveness'ofthe weight 25 and-to change the pressure dillerential maintained'by the device 20in stepsrepresented by pressure increments sent'intothe'line' 37 and produced primarily by the stepping up of the valve stem 18 and'consequent opening of the" valve 8. '1 Thus, it will be noted that the operation of the demand responsive valve 8 results in chosen for the purposes of illustration to in- N crease the pressure ditlerential ratio as the valve 8 opens, and in like manner, to decrease the ratio as the valve closes, yet, it must be understood that I donot wish to so limit the .scope of my invention. For, the bellows 38 may beflevered in a manner to aid the weight' 25 when the valve 8 is being opened, and to reduce the effectiveness of the Weight when the valve is being closed, instead of the opposite arrangement as above described.

Although I have described a particular arrangement of this invention in more or less detail, it will be apparent that various changes, additions, substitutions, and omissions can be made therein Without departing from the spirit of this invention or the scope of the appended claims.

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

1. In combination with a boiler having a feed water line, a feed water control valve in said line, means for operating said valve in response to demand for feed Water by said boiler, pressure control means for varying the water pressure in said line on the inlet side of said valve, and an additional mechanism responsive in operation to the drop in pressure across said valve and the position of said valve controlling said pressure control means for increasing the pressure differential across said valve as said valve opens and for decreasirlig such pressure differential as the valve 0 oses.

2. The combination with a boiler hav ing a feed water supply line connected thereto, a-throttle valve in said line, means responsive to variations in the water level in' the boiler for operating the throttle valve,

and a valve in said line adapted to vary the water pressure 'on the inlet side of the throttle valve, of pressure actuated mechanism controlled by and in accordance with the position of the throttlevalve for actuating said second mentioned valve so as to increase the pressure at the inlet of the throttle valve as the throttle valve opens. and to decrease the inletpressure as the throttle valve closes, said pressure actuated mechanism including means responsive tojthe pressure drop across the throttle valve for so actuating said sec- 0nd mentioned valve as to maintain the differential resulting across the throttle valve, for each position thereof, substantially constant.

In testimony whereof, I have hereunto subscribed I'ny namethis 28th day of June, 1928.

THOMAS A. PEEBLES.

Leo

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