US1904553A

US1904553A - Feed water regulator

Info

Publication number: US1904553A
Application number: US316757A
Authority: US
Inventors: Smoot Katherine
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-11-02
Filing date: 1928-11-02
Publication date: 1933-04-18
Anticipated expiration: 1950-04-18

Description

April 18, 1933. c H. SMQQT 1,904,553

FEED WATER REGULATOR Filed Nov. 2, 1928 I I 15 I K is 15. 7 4 i 31 Fig. 2 3o boikr RnHns INVENTOR Charles H Jmoot,

ZMM/ ATTORN EYS Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE CHARLES H. SHOOT, OF MAPLE-WOOD, NEW JERSEY; KATHERINE SHOOT EXECUTBIX O! SAID CHARLES H. SHOOT, DECEASED man warns. uncommon.

Application m November 2, 1923. Serial no. 316,757.

My invention relates to the art of regula-.

tion and more particularly to a novel method 7 of regulating the supply of feed water to boilers. It comprises as well novel apparatus that is simple of construction, reliable and economical and adapted to be used in carrying out the method.

The prime necessity in the regulation of boiler feed water is that of safety both to,

the boiler tubes and to the turbines or other steam consumers fed by the boiler. The water level in the boiler drum depends not only upon the quantity of water in the boiler but also upon the amount of steam generated within the boiler tubes. It therefore fluctuates widely upon sudden changes in load due to collapsing of the steam in the tubes upon sudden decrease in heat input, and to formation of such steam upon sudden increase'of heat input. If the level becomes too high there is considerable danger of entrained water in the steam passing to the steam consumers. On the other hand, too low a level .of water introduces the grave chance that the boiler tubes may become burned out with the consequent danger to the safety of the plant operators. In the modern type of flash boiler, the control of the feed water is of paramount importance, as these dangers of too hi h or, too low level of water are accentuated y the small storag capacity of these boilers.

7 The usual type of constant water level -regulator, as exemplified by a float device opening a valve in the feed water pipe upon decrease in level and closing the same upon increase in the level tends to maintain a water level inversely with the rate of steaming.

with a consequent reduction in water level.

If the regulator has been set tom'aintain a low level, it will immediately open, permitting a supply of relatively cold water, caus= counteracting effect of the cold water, re- 1 sulting in further expansion and rise, with the possibility of carrying over entrained water.

I have devised a method of feed water regulation which avoids the difliculties above described, and is inherently stable, as I insure a water level which varies directly with the rating in the same direction as does the natural level resulting from the presence or absence of steam generation within the tubes. For the same increase in heat input' the magnitude of the natural increase in water level due to steam formation within the tubes decreases as the rating increases due to the greater velocity of water circulation at high rating. I, therefore, vary the water level with rating in such a way that if water level is plotted against rating, with rating as abscissae, the resulting curve is convex upward, approaching a maximum for high ratings. I have found that if the water level is regulated to follow such a curve, safety and stability are achieved. I have devised, therefore, a very simple arrangement which, when properly adjusted, regulates the feed water so that the water level closely follows the shape of the desired curve with rating.

For a better understanding of my invention and of my novel apparatus for controlling the feed water, reference should be had to the accompanying drawing of which Fig. 1 illustrates diagrammatically one form of regdulator adaptedto carry out my invention, an

Fig. 2 illustrates the variations of water level with boiler rating when regulated according to my invention.

Referring to Fig. 1 the boiler whose feed water supply is to be regulated is indicated filled with water from the boiler becau'seof the connections now to be described.' The space above the mercury in chamber 8 is in communication by means of a flexible tubing 9 with a smallchamber 10- in which is maintained a constant level of water derived from the condensation of the steam which enters the chamber 10 from the upper end of the boiler watercolumn 11 through a pipe 12. The chamber 8 pressure varies therefore directly with steam pressurevariations.

The space above the mercury in chamber 7 is connected through a flexible tubing 13 with twopipes .14 and 15, the former of which leads to the lower end of the boiler water column and the latter of which leads to the mud drum 3. The flow ofwater from the drum 2 to the mud drum 3 through the

pipes

14 and 15 is controlled by manually adustable valves 16 and 17 in

pipes

14 and 15 respectively. As the flow of water through pipes 14 and 15 'is in shuntwith part of the water circulating in the boiler, it willincrease and decrease as the rating increases and decreases respectively, and its actual magnitude at any rating will depend upon the setting of the valves 16 and 17. The pressure in chamber 7 will depend upon the flow of water through the

pipes

14 and 15, upon the water level in the drum 2' and upon the steam pressure. The difl'erential in pressure, therefore, between the chambers 7 and 8 will depend upon the difference in waterlevel between that in the chamber 10 and in the drum 2, and also upon the flow of water-through pipes-14 and 15.

i The apparatus now tobedescribedeflects the control of the valve 5 in response to variations in this pressure difl'erential to maintain the same constant. Insofar as the invention herein claimed is concerned, the particular means by which such control is effected is immaterial, as any suitable means for efl'ecting such control is within'the scope of'the present invention. The particular modification illustrated, comprising the casing 6 and associated parts, together with certain other features of invention, will form the subject matter of another one of my applications and is therefore disclaimed herecasing 6 is mounted on a ivot 18 and the left-hand .end is connected t rough -a member In the particular modification illustrated,

19 and spring 20 with a movable lever arm 21. The lever 21 is pivoted at 22 and carries an'adjustable weight 23 to oppose the force upon the lever created by the tipping of casingfi. The movement of lever 21' is arranged to control the valve 5 in the feed Water supply pipe. To effect the movement of the valve 5, I connect a throttle valve 24 to the lever 21, the position of which controls the pressure of fluid in a chamber 25 beneath a power piston 26. The piston 26 carries a piston rod 27, on the upper end of which is a dashpot 28, the piston 29 of which is connected to:the lever 21. A source of fluid' under pressure is connected through a pipe 30 and a restricted orifice 31 with the chamber 25, the fluid escaping from cham- -ber 25 past the throttle valve 24 and into pipe 32. Hingedly connected to the piston rod 27 is alever 33, one end of which is pivoted to a fixed support at 34, the other end of which through

suitable links

35 and 36 the difference in pressure between chambers 7 and 8 depends substantially entirely upon the level of the water in the boiler drum 2 and varies inversely therewith. As the steaming rate increases, an increasing flow of water occurs through

pipes

14 and 15 causing a decreasing pressure in chamber 7 due to the pressure drop of the water flowing past valve 16 toward valve 17. As the regu- Iator maintains a constant differential in pressure between chambers 7 and 8, it follows that as this differential variesinversely withthe level of the water in the boiler drum and varies directly with the flow of water through

pipes

14 and 15, the; level, of the Water in the boiler drum 2 must increase to compen-' 'sate for the effecton the regulator of the increasing flow of water through pipes-14 and 15 with increasing rating. At high rating, therefore, sure difference between the chambers as at low'rating, but this pressure difference at high rating will be due toa highwater there will be the sam presand-8 level anda large pressure drop due to flow,

and" at low rating this pressure difference Wlll be due to a low water level and a small pressure drop due to flow.. At High loads with a high load followed immediately by a reduction in water level a sudden decrease in.

fuel feed-to reduce the rating and prevent undue building upof pressure, causes the v collapse of someofthe steam in the boiler tubes and a consequent decrease in the water level in the boiler and likewise a decrease in the flow of water through

pipes

14 and 15. If the pressure drop in chamber 7 occasioned by the reduction in water level is exactly compensated for by the increase in pressure occasioned by the reduced water flow, the regulator will be unafiected and the valve 5 remain in its former position, allowin the same quantity of water to enter the boi er as it did for the higher load. But as the steam consumption has been reduced due to reduction in load, the excess water supply will tend to gradually increase the water level, but this increase in level will be immediately felt as a pressure difference u n the re lator, causing mercury to flow rom cham r 7 to chamber 8, thus tipping the casing in a clockwise direction and exerting an upward force upon the left-hand end of lever 21 causing a decrease in pressure in chamber 25 due to the artial opening of the fluid outlet by throtte valve 24. The decrease in pressure in chamber 25 lowers piston 26 and 7 thereby causes a partial closure of valve 5 to cut down the feed water in proportion to the reduced steaming rate.

Although I have described the chambers 7 and 8- as being directly in communication with pipes 13 and 9 respectively, I prefer to employ check valves as shown to avoid any possibility of mercury under excess pressure enterin pipes 13 and 9, as these pipes are prefera ly constructed of steel which would be attacked by mercury.

Referring now to Fig. 2, the curves show the change in water level with boiler rating convex upward as desired for stable regula-- tion. The steepness of these, curves of Fig. 2 may be regulated at will by the valves 16 and 17 of Fig. 1, an opening of 16 and a closing of valve 17 tendlng to reduce the steepness of the curves. The preferred adjustment of these valves will depend upon the capacity of the water drum of the particular boiler under control, a lar capacity rmitting of a wide variation in level, an therefore a steeper curve and conversely a small capacity requiring a small variation in level or a flatter curve. The weight 23 of Fig. 1

does not afiect the steepness of the curves of 4 Fig. 2, but varies the relationship between the water level and rating,that is, if curve A corresponds to the curve obtained from the weight 23 in the position shown, then a setting ot the wei ht 23 nearer to the pivot 22 than shown wi give a curve in the position of curve B of Fig. 2, whereas a setting oi the weight 23 further from the pivot 22 will give a curve like 0 of Fi 2.

I have now descri my novel method of regulating the feed water to boilers and one modification of my ap ara'tus designed to carry out the methode arran ment illustrated and described is that which Iconsider referable insofar as the boiler drummud rum diflerential is employed to efl'ect the action of a constant water level regulator. This differential when properly adjusted, as above described, will giveapropershapecurve for increase of water level with rating and may be made to follow the same type of curve as does the natural level resulting from the change in formation of steam within the boiler tubes.

When the regulator above described is so adjusted as to vary the water level to follow the exact magnitudes of the natural variations above described, a constant weiglft of water in the boiler at all loads is obtained. Such water level variations corresponding to a constant weight of water are within the scope of my invention and might be obtained by other means. For example, the variations in the weight of boiler and water might be used to act upon a regulator to maintain the same constant. The practical difficulties in such an arrangement are of course obvious,

but not perhaps insurmountable in view of the modern practice of hanging boilers from overhead su ports.

I believe it is broadly new to so regulate the feed water to the boiler as to increase the water level with rating, and I likewise believe it to be new to utilize the boiler drum-mud drum differential in conjunction with a constant water level regulator to so vary the water level. 1

I claim:

1. A boiler feed water regulator comprising water level responsive means adapted to I control the supply of feed water to maintain a constant water level, means responsive to the circulation of the water through the boiler and adapted to modify the action of said first mentioned means whereby increas- .ter supply pipe, a valve in said supply pipe,

means for permitting a by-pass flow from the water drum to the mud drum, a device res nsive to a force varying inversely with t e level of the water in the drum and to a force varyin directly as the rate of flow through said y-pass, and means for controlling said valve by said device in response to variation in said forces.

3. Apparatus as in claim 2 including means for manually adjusting the flow through said by-pass.'

4. In combination with a boiler having ply pipe, a valve in said supply pipe, a bypass pipe connection between said drums, ad- ]usta le valves in said by-pass pipe, a device comprising two chambers, a pipeconnecting I water and mud drums and a feed water supone of said chambers with said by-p'ass pipe intermediate said valves,'connecting means between said other chamber and the steam space of the water drum, and means for controlling the valve in said feed water supply pipe by the diflerential between the pressures in said chambers.

5. The combination according to claim 4 wherein the connection between the space above the water in the water drum and said other chamber includes a vessel adapted tc tion through the boiler and adapted to modify the action of said first mentioned means whereby the water level is maintained increasingly higher with increasing water circulation, and decreasingly lower with decreasing water circulation.

7 In combination with a boiler having a water drum and a feed water supply pipe,

a valve in said supply pipe, means for permitting a by-pass flow between two points of said boiler, a device responsive to a force varying inversely with the level of the water in the drum and to a force varying directly as the rate of flow through said by-pass, and means for controlling said valve by said device in response to variation in said forces.

8. In combination with a boiler having a water drum and a feed water supply pipe, a by-pass pipe connection between two points of said boiler between which there is a substantial pressure difference due to the circulation of-water through the boiler, adjustable valves in said by-pass pipe, a device comprising two chambers, a pipe connecting one of said chambers with said by-pass pipe intermediate said valves, connecting means between said other chamber and the steam space of said water drum, and means for controlling the valve in said supply pipe by the difl'erential between the pressures in said chambers.

9. The method of regulating the supply of feed water to a boiler which consists in so correlating the feed water supply with a sponsive to the circulation of the water within the boiler circulatory system and adapted to modlfy the action of said first mentioned means for maintaining increasingly higher CHARLES H. SMOOT.