US2411729A - Feed water regulating apparatus for boilers - Google Patents

Description

Nov. 26,1946. 7 w HUNTER 2,411,729

' FEED WATER REGULATING APPARATUS FOR BOILERS Original Filed April 14, 1942 2 Sheets-Sheet 1 IN VEN TOR. W/LL/AM L. HUNTER Nov. 26, 1946. w. L. HUNTER FEED WATER REGULATING APPARATUS FOR BOILERS Original Filed April 14, 1942 2 Sheets-Sheet 2 YINVENTOR. w/u mm L HU/V 75/? w. x 7 MM HTTOIFNEV Patented Nov. 26, 1946 uN TEo S PATENT OFFICE FEED WATER REGULATING APPARATUS EORBO ILERS William L. Hunter, Erie, Pa., assignor to Northern Equipment Company, Erie, Pa., a corporation of Pennsylvania 7 Original application April 14, 1942, Serial No.

438,960, now Patent No. 2,365,081, dated December 12, 1944. Divided and this application September 20, 1944, Serial No. 554,997

although not limited to such use.

The present invention is a division of my copending application Serial No. 438,960, filed April 14, 1942, which has become United States Patent 2,565,081, and which issued to me December 12, 1 44.

As is well understood, it is desirable to automatically regulate the feed water supply to boilers and maintain the boiler water level within pr'e-determine'd limits. This has commonly been effected in stationary boilers by'having a tube '01 the like in communication with the steam and water space of the boiler whereby the water level in the tube will correspond to the water level in the boiler and regulate the feed water valve in accordance with tube water level. However, such apparatus is not satisfactory for marine boilers since the tube water level is materially disturbed by the rollof theship resulting in rapid and highly undesirable fluctuations in the amount of feed water being fed to the boiler.

I am aware that it has previouslybeen proposed to compensate for ship roll by employing two tubes or the like fixed to each side of the boiler and laterally outward thereof whereby as the boiler is tilted due to ship roll a drop in water level inone tube will be accompanied by a corres'po'nding rise in the other tube. Both tubes are adapted to influence the feed water supply so that a compensating effect is achieved with a relatively small angular ship roll. However; since each tube is necessarily disposed 'a substantial distance from the verticalicenter line of the boiler considerable fluctuation in tube water level results and with considerable angular roll the'tubes may be emptied or completely filled. Practical considerations limit the height or extent of. the tubes and it is apparent that if the Water-level is extended'beyond the tube limits that the con vtrol'of the feed water will be erratic.

It is a primary object of my invention to'pro- 'improved feed water regulating apparatus for boilers which can be easily installed on a conventional boiler and which is readily adjustable.

ther objects of the invention will be increasingly apparent from a consideration of the following description and drawings.

.According to the invention, a generally V shaped tube adapted to expand and contract under thermal change is mounted externally of the drum head of a boiler with the apex of the tube being disposed substantially on the vertical center line of the boiler and the tube armsextending at substantially equal angles at each side of the center line. The apex of the tube is fixed and ends of the arms are free to move under thermal change. Each of the arm ends is connected to separate rock levers which are pivoted laterally of each'arm. A third'lever is pivoted to one of the rock levers and is pivotally connected to the other rock lever by link means whereby expansion of one tube arm a given amount and contraction of the other tube arm an equal amount will efiect no change in theposition of the third lever. The apex of the, tube and the end of each tube arm are connected to the boiler whereby in a stationary boiler the length of each arm will at all times be substantially the same, and will be determined by the boiler water level.

When employed on a marine boiler one tube arm will expand and the other will contract in accordance with the amount the boiler is tilted froma normal position but the composite action will not materially effect the position of the third lever. Due to the normal water level in each tube vide improved feed .water regulating apparatus for boilers. V 4 -Another object of my invention is .to provide feed water regulating apparatus for boilers. and

which is particularly adapted to marine boilers whereby an accurate control of the feed water ,will be maintained responsive to the'steamdemands despite considerable angular roll of the ship; v 1 I opposite. sides of arm being only a short distance laterally from the vertical center .lineoi the boiler only fluctuates through relatively short distances despite considerable angular roll of the ship and well within. the tubelimits. In one embodiment movement of the third lever controls the operation of the feed water valve jointly with a lever operable by a fluid pressuremotor but each said lever can actuate the valve independent of movement'ofthe other lever; The fluidpressure motor is in communication with steam pressure in the boiler and super-heater steam pressure at a diaphragm whereby the motor lever will be actuated bypressure differential on Ina new,

the diaphragm in accordance variations in the system. a V

In a modification of the invention, a pilot valve is operated responsive to boiler water level variawith steam flow tions which controls'a fluid'pressure motor autuating the feed water valve.

the water level od fi o tzaflu sir essu e in tor operatively connected to the feed water valve is controlled by a pilot valve responsive to the composite efiect of steam flow variations in the system and boiler water level variations.

Each of the embodiments disclosed employ the same general arrangement for actuating a first lever through a V shaped tube of thermally expansive material, a pair of rock levers operable by expansion and contraction of the tube arms and link means, the mechanism being arranged so that the said first lever and resultantly the feed water valve is substantially unaffected by tilting of the boiler.

In the following description and drawings:

Fig. 1 is an end elevational view largely diagrammatic, of a boiler and my improved regulating apparatus,

Fig. 2 is an end elevational view, largely diagrammatic, showing a modification of my invention,

Fig. 3 is a right side view of the apparatus illustrated in Fig. 2 with the fluid pressure motor and fluid line omitted for clearness of illustration,

Fig. 4 is a view, generally similar to Fig. 2,

showing a further modification of the invention,

Fig. 5 is a right side view of the apparatus for Fig. 4,

Fig. 6 is a horizontal section taken along the line 66 of Fig. 4, and

Fig. 7 is a vertical sectional view of a pilot valve which I may employ.

Referring now to the drawings, and particularly Fig. 1, I have shown an embodiment of my invention, wherein the end portion or head of a boiler drum is generally indicated at iii and flow through the feed water supply line H is controlled by a valve I2 which is connected to the lower portion of the boiler drum by a line IS.

The regulating apparatus for operating the feed water valve responsive to boiler water level and which is relatively unaffected by tilting of a marine boiler will now be briefly described, this apparatus being more fully described in my aforesaid Patent 2,365,031. A generally triangular shaped frame I4 preferably formed of iron or a similar material relatively unaffected by thermal change may comprise a pair of triangular shaped spaced members of channel cross-section with suitable cross spacing members therebetween.

However, since the frame is installed in a zone of relatively constant temperature it may be made of any suitable material as its dimensions remain practically constant. The frame may be supported from the feed water line or in any suitable manner. hers is a thermostatic tube of inverted V form,

Disposed between the frame memthe apex of the tube communicating with a line l 6 extending to the steam space of the boiler and being locked to the frame by a nut IT. The tube arms are inclined at substantially equal angles to the vertical center line of the drum head and are of substantially equal length. The tube apex is disposed at the vertical center line with the horizontal center line of the arms preferably slightly below the normal water level of the boiler.

As best illustrated in Fig. 4-, a rock lever I8 is pivoted between the frame members as indicated at 19 and is pivotally connected to the free end of the left hand tube arm as indicated at 2| A second rock lever 22 is connected in a similar manner to the free end of the right hand tube arm and is pivoted as indicated at 23. The free ends of the tube are inter-connected by a pipe 24 which communicates with the water space of the boiler through a pipe 26. A lever 27 of inverted L form is pivotally connected to the top portion of rock lever 22 and a link arm 28 is pivotally connected to this lever, as indicated at 29, and to the other rock lever l8 at 3|. A series of holes may be provided along lever 2! to provide an adjustable connection whereby for a given movement of either rock lever a greater or lesser movement of lever 27 will be efiected.

The operation of the apparatus so far described is as follows. Assuming the apparatus to be used on a stationary boiler or on a marine boiler disposed parallel to the fore and aft center line of the ship and that the ship is riding at an even keel, the water level in both arms of the thermostatic tube will be the same and will correspond with boiler water level. Upon a decrease in boiler water level there will be a, similar decrease in both arms and an increase in the amount of steam in each arm causing both arms to expand an equal amount whereupon rock lever l8 will be rotated in a clock-wise direction and move lever 27 in a clock-wise direction. Rock lever 22 will move in a counter-clock-wise direction and further move lever 21 in a clock-wise direction. In a manner to be explained this movement of lever 2'! will cause the feed water valve to move in an opening direction. An increase in boiler water level will cause a reverse action but in each instance the action of the rock levers will be cumulative rather than opposed.

If the apparatus is used on a marine boiler and the ship is rollin the water level in each tube arm will alternately rise and fall since frame I4 is fixed to and will move with the boiler. As the boiler is tilted in clock-wise direction the left hand tube arm will be raised and the water level therein will be lowered causing the arm to expand and resultantly lever 27 will tend to move in a clock-wise direction. However, the right hand tube arm will be lowered causing the water level therein to increase thereby contracting the arm and tending to move lever 21 in a counterclock-wise direction with the net result that lever 2'! is not appreciably effected by ship roll and an accurate control of the feed water is maintained since the feed water valve is operated in accordance with movement of lever 21 as will be now described.

' A strut 32 including tension relief means 33 is pivotally and adjustably connected to lever 27 and is operatively connected to a fluid pressure motor 34 actuating valve [2 by suitable link means which may comprise a chain 36 reeved through a pulleyS'l, ad-justably mounted on an L shaped lever 38, and adjustably connected to an arm 39. Lever 38 is fixed to and adapted to actuate a shaft ll which actuates the valve plunger. Am 39 is operably responsive to steam flow variations in the system in a manner to be described so that the valve is operated in response both to boiler water level variations compensated for ship roll and steam flow variations in the system. Any suitable valve may be employed but I preferably use a valve of the type more fully described and illustrated in U. S. Letters Patent 2,270,094, issued to V. V. Veenschoten January 13, 1942.

Arm 39 is operatively connected to a diaphragm -(not shown) disposed in the upper portion of the valve housing and movable by difierential fluid pressure. One side of the diaphragm is subject to steam pressure in the boiler by a line 42 and the other side to superheater steam pressure by a line 43 extending from the outlet 44 of the superheater 46. I preferably provide a capacity tank or reservoir 41 in each line so that the liquid level variation in each line due to diaphragm movement under pressure change will be relatively small. As is more fully explained in the aforementioned Veenschoten patent arm 39 operates lever 38 in accordance with the steam flow variations in the system and as previously explained lever 21 operates lever 38 in accordance with boiler water level variations so that the feed water valve is operated responsive to the composite effect of steam flow variations and water level variations. A tension spring 48 having one end fixed to the valve housing and its opposite end secured to the depending arm of lever 38 maintains tension in the link means operating the feed water valve.

Referring now to Figs. 2 and 3, I have shown a modification of the invention in which the frame l4 and associated parts are mounted in fixed relation to the drum head of a boiler as explained in connection with Fig. 1 but in'this embodiment the lever 21 is replaced by a Z shaped lever 49. Lever 49 is pivoted as indicated at 5| to the upper end of rock lever 22 whereby as previously explained a drop in boiler water level will cause lever 49 to be rotated in a clock-wise direction and elevate the upper horizontal arm 52 of lever 49. Tension springs 53 are connected to the lower horizontal arm 54 of lever 49 and the frame l4. Arm 52 acts against an abutment 56 slidably adjustable along a lever 51 pivotally mounted as indicated at 58 on a bracket 59.

Lever 51 is loaded by a pair of tension springs I 4 6| connected to the left hand, end of the lever and bracket 59. Abutment 56 preferably comprises a threaded element 62 for regulatingthe spacing between arm 52 and lever 51 and resultantly the tension exerted by springs 53 and 6 I.

Lever 51 bears against and actuates the adjustable stem 64 of a pilot valve generally indicated at 63, the pilot valve being of the type adapted to produce a fluid pressure proportional to stem displacement. Pilot valves of this type are well known and in Fig. '7 a valve of this type is diagrammatically illustrated wherein movement of the stem 64 having spaced piston valves thereon controls entry of a fluid under substantially constant pressure from a port 65-to the valve casing and also controls the passage of excess fluid through a port 66. The fluid may be air, city water or the like which communicates through port 61 and line 68 with a remotely disposed fluid pressure motor 69 adapted to operate the feed water valve. The fluid pressure motor may comprise a chamber 1| having its base formed by a diaphragm movably responsive to fluid pressure changes. The diaphragm has its lower side exposed to atmosphere and downward movement thereof under increased fluid pressure in the chamber is opposed by a spring 12. The

diaphragm operates a stem 13 pivoted to the arm of a rock shaft 14 which projects within the valve casing and byinternal linkage actuates the valve piston in a Well known manner.

It will now be understood that I have provided an arrangement wherein a pilot valve is operated responsive to water level variations in the i boiler, compensated for ship roll in a marine boiler, the pilot valve controlling transmission of fluid from a source under substantially constant pressure to a fluid pressure motor operating theboiler feed valve in accordance with fluid pressure. changes.

Referring low to Figs. 4 to 6 inclusive I have shown a further modification of my invention,

lever 16 pivoted at may be of the-type generally similarto the embodiment of Fig. 1, wherein a servo-motor is employed and a pilot valve responsive to the composite efiect of steam flow variations in the system and boiler water ,level variations controls a fluid pressure motor operatively connected to the feed water valve. The rock levers l8 and 22 and link arms '28 are operated as previously described in response to boiler water level variations whereby an L shaped the upper portion of rock lever 22 is rocked in a clock-wise direction upon a decrease in water level and in reverse direction upon an increase in level. The upper portion of lever 16 is slotted to receive an adjustably mounted pin 11 which abuts the depending arm of a lever 18 and is held thereagainst by a pair of tension springs 8| connecting lever 16 and an arm 19 extending from the frame l4. Lever'18 has a horizontally extending arm 82 which is journaled on a pin 83 projecting from the depending arm- 84 of a bracket extending .from the housing of the fluid pressure motor 86.

Link 88 is slotted to receive an adjustably' mounted pin 9| which pivotally connects the link with an arm 92 fixed to a shaft 93 rotatably supported by the housing of fluid pressure motor 86 and having a portion sealingly projectinginto the housing. An arm 94 within the housing is fixed to shaft 93 and is pivotally connected to a rod 96 secured to a diaphragm 91. The diaphragm is loaded on its upper side by a compression spring. It is well knownthat steam flow variations from a boiler may be measured by pressure differential caused by resistance in the steam line such as a superheater, an orifice, Pitot tube, or friction through a section of the steam line. The diaphragm divides the housing into upper and lower chambers and the lower chamber is connected with the upstream or high pressure side of the resistance such as the superheater inlet through a line 98. The upper chamber is connected to the downstream or low pressure side of the resistance being measured, such as the superheater outlet, through a line 99.

The pilot valve' 63 is similar to that described in connection with Figs. 2, 3 and 7 and line 68 leads from the pilot valve to the fluid pressure motor operating the feed watervalve. The motor described in connection with Fig. 2. The flow of feed water to the boiler is controlled by the apparatus described in the following manner. As the boiler water level decreases lever 16 will be rotatedin a clock-wise direction and through pin 11 will rotate lever 18 in acounter-olock-wise direction about pin 83. Arm 82 of lever 18 will carry pin 81 downwardly against the tension of springs 89 and cause link 88 to rotate about pin 9| and permit pilot valve stem 64 which it bears against to move downwardly under the influence of the stem spring. This movement of stem 64 causes a decrease in fluid pressure in line 68 whereby the fluid pressure motor will cause the feed water valve to open more. Upon an increase in boiler water level the action will be reversed and. the stem 64 will be moved upwardly to move the feed water valve in a closing direction.

Upon an increase in steam flow in the system direction due to a relative increase in pressure on the underside of diaphragm 91 and this movement will carry pin 9! upwardly causing link 88 to rotate clock-wise about pin 87 and permit the stem 6 of the pilot valve to move downwardly which will cause the feed water Valve to open more as previously described. Upon a decrease in steam flow in the system the action will be reversed to move the feed water valve towards a closed position. Thus, the pilot valve and resultantly the fluid pressure motor controlled thereby and actuating the feed water valve is re-- sponsive both to boiler water level variations and steam flow variations in the system.

It will be noted that in all the embodiments described a lever (lever 21 of Fig. 1, lever 49 of Fig. 2, and lever 16 of Fig. 4) is actuated responsive to boiler water level variations but that the lever is relatively unafiected by tilting of a marine boiler in alternate directions about an axis extending longitudinally of the boiler. Movement of the lever correspondingly controls or effects operation of the feed water valve in association with a fluid pressure motor. In the embodiments of Figs. 2 and 4 a pilot valve is employed for controlling the operation of a fluid pressure motor actuating the feed water valve and in the embodiments of Figs. 1 and 4 the feed water valve is actuated both in response to boiler water level variations and steam flow variations. In the embodiments of Figs. 1 and 4 it will be noted that although the feed water valve is jointly controlled by the boiler water level and steam flow responsive means that each means is adapted to independently actuate the valve. For example. if the boiler water level responsive lever 21 of Fig. l or arm 82 of Fig. 4 remains stationary the valve will be actuated responsive to the steam demands of the system. Conversely, if the steam flow is constant lever 39 of Fig. 1 or arm 92 of Fig. 4 will remain stationary and the valve will be actuated responsive to boiler water level variations. Although I have shown and described preferred embodiments of the invention I contemplate that numerous and extensive departures may be made therefrom without departing from the spirit of my invention and the scope of the appended claims.

The invention is hereby claimed as follows:

1. Feed water regulating apparatus for boilers comprising a boiler drum, a generally V shaped thermostatic tube having its apex fixed relative to the drum and substantially at the vertical center line of the drum, the tube arms extending at substantially equal angles to said center line and being freely movable under thermal change, one end of each arm communicating with the steam space of the drum and the opposite end with the Water space thereof whereby the water level in each arm will correspond with boiler water level, a feed water valve, a fluid pressure motor adapted to actuate the valve, means connected to the free end or each tube arm and to the motor for actuating the valve in accordance with the composite water level in the tube arms, and means responsive to steam flow variations in the system for operating the motor independently of the level responsive means.

2. Feed water regulating apparatus for boilers comprising a boiler'drum, a generally V shaped thermostatic tube having its apex fixed relative to the drum and, substantially at the vertical center line of the drum, the tube arms extendingat substantially equal angles to said center line and being freely movable under thermal change, one end of each arm communicating with the steam space of the drum and the opposite end with the water space thereof whereby the water level in each arm will correspond with boiler water level, a feed water valve, a valve operating lever, a fluid pressure motor operably responsive to steam flow Variations in the system, a lever movably responsive to the composite thermal change in the tube arms, and link means inter-connecting said lever with the motor and valve operating lever whereby the feed water valve will be operated under the joint influence of steam flow variations and boiler water level variations. 3. Feed water regulating apparatus for boilers comprising a boiler drum, a generally V shaped thermostatic tube having its apex fixed relative to the drum and substantially at the vertical center line of the drum, thetube arms extending at substantially equal angles to said center line and being freely movable under thermal change, one end of each arm communicating with the steam space of the drum and the opposite end with the water space thereof whereby the water level in each arm will correspond with boiler water level, a feed water valve, a fluid pressure motor for actuating the feed water valve, a pilot valve controlling operation of the valve motor, means controlling operation of the pilot valve, said pilot valve controlling means comprising a servo-motor responsive to steam flow variations in the system, a lever movable in accordance with the composite water level in the tube arms, and means operatively inter-connecting the servo-motor, pilot valve, and lever whereby the feed Water valve will be operated under the joint influence of steam flow and water level variations and independently of concurrent variation.

4. Feed water regulating apparatus for boilers comprising a boiler drum, a pair ofarms formed of thermally expansible material mounted on one head of the boiler drum and lying within the head periphery, the arms being of substantially equal length and each extending above and below the normal water level in the drum, the arms being substantially symmetrically disposed at opposite sides of the vertical center line of the drum, the upper end of each arm communicating with the steam space and the lower end of each arm communicating with the water space of the drum whereby the water level in each arm will correspond with boiler water level, the same end of each arm being fixed and the opposite ends being freely movable under thermal change, a feed water valve, a fluid pressure motor adapted to actuate the valve, means responsive to the composite movement of the free ends of the arms and connected to the motorv for operating the valve, and means responsive to steam flow variations in the system for operating the motor.

WILLIAM L. HUNTER.

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