US1172243A - Boiler feed-water regulator. - Google Patents

Description

R. W! ANDREWS.

BOILER FEED WATER REGULATOR.

APPLICATION FILED 0013. 1913.

Ll'?2 2%3. Patented Feb. 13, 19h).

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M'a fi.%eML/ Maw 4- W 6 im'miif To all whom it may concern barren snares ROGER w. ANDREWS; or PITTSBURGH,

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PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO ERIE PUMP & EQUIPMENT COMPANY, OE ERIE, PENNSYLVANIA,

A CORPORATION OF PENNSYLVANIA.

BOILER r1:sin-warren,v REGULATOR.

Application filed October 3,

Be it known that I, Roonn VV.'ANoREWs, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have inventedcertain new and useful Improvements in Boiler Feed-Tater Regulators, of which the following is a specification.

This invention relates to regulators to be used in connection with boilers in order to control the level of the water in the boiler.

It has long been common in the practice of steam engineering to maintain, as uniform as possible, the height of the water level in stationary boilers; and this is frequently done by means of automatic devices, requiring substantially no attention of the boiler operator, as this is much better practice than to depend upon the boiler operator himself to maintain manually a uniform water level. I have found, however, that the maintaining of a uniform water level in the boiler is desirable only when the load upon the boiler is uniform; that in case of boilers carrying varying loads, it is desirable, not only because of the greater econ omy, but also because of the greater boiler capacity, to vary the elevation' of the Water level in the boiler more or less in accordance with the load which the boiler is carrying. In this way the fire may be kept substantially constant and in the most efiicient condition. \Vhen the load upon 'the'boiler is light, it is better to allow more water to enter the boiler and to' use the surplus heat of the fire in heating this surplus water, rather than to allow the heat to evaporate more water and blow the steam off at the safety valve, or to let the fire die down. If the heat, instead of being wasted at the safety valve, is used in heating incoming water, so that when the heavy load comes upon the boiler, it will find the boiler substantially Specification of Letters Patent.

Patented Feb. 15, 19116.

1913. Serial No. 793,159.

increases the amount of steam produced.

Heretofore, it'has been customary to increase proportionately the water flow during heavy load periods; this has lowered the temperature of the water in the boiler and thus retarded evaporation, and by raising the water level reduced the steaming area. In view of these facts, the object of this invention is to determine a method by which to adapt the water level in the boiler to the load upon theboiler, so as to increase the efliciency and capacity of the boiler, and to provide means for properly carrying out the method.

In general the method which I prefer consists in supplying, during light loads, more water to the boiler at first than isused, substantially as much as is used with normal or average loads, and then, as thelight load continues, gradually reducing the amount until a Water level is reached corre sponding to the load, when the inflow equals the outflow; and, in case of heavy loads, in supplying less water at first than is used, and then, if the heavy load continues, in gradually increasing the amount supplied until a level is reached which corresponds to the heavy load, when the inflow again equals the outflow. The means by which this preferred method of supplying water to the boiler is carried out, in this instance, are illustrated by the accompanying drawings, in which Figure 1 is an elevation, partly in section, of a boiler and a feed-water regulator which embodies the I features of my invention. Fig. 2 is a section of the special form of feed-water valve used in connection with the regulator; and Fig. 3 is a section of a portion of the regulator along the line 3-3 of Fig. 1.

V In the drawings the boiler is indicated by the reference number 4. The normal or average water level in the. boiler is indicated by the dotted line 5 the minimum water level by the dotted line 6, and the maximum water level by the dotted line 7.

The feed-water regulator comprises an expansion tube 8 mounted on the supports 9 and 10, which are fixed in any suitable mannor; to the T-base 11. The base 11 is supported inany suitable manner in such a way as to bring the central portion of the expansion tube 8 at about the same elevation as the average or normal water level in the boiler; the lowerend of the expansion tube at about the same elevation as the minimum water level; and the upper end of the ex.- pansion tube at about the same elevation as the maximum water level.

Pivoted to the upper end of the support 10 by means of the pin 13, or in any other suitable manner, is a lever 15. The upper end of the expansion tube 8 is pivoted at the point 12 to the short arm of the lever 15; and connected to the outer end of the long arm of the lever is any suitable member such as a r0d 17 which supports the long arm 18 of a second lever 19, which is adapted to operate the feed-water valve 20 of the supply pipe 21. A weight 14 eliminates at all times any looseplay in the connections between the expansion tube 8 and the valve 20, and also causes the valve to operate when allowed to do so by the contraction of the expansion tube 8.

The location of the upper end of the expansion tube 8, with reference to the fulcrum 13 of the lever 15, may be adjusted by means of the nuts 16; and the relation of the position of the valve cylinder 2l to the outer end of the long arm of the lever 15 may be adjusted by means of the nuts 16. If for any reason the Weight 14 should not be sufliciently heavy to actuate the cylinder of the valve 20 when the tube 8 contracts, the long arm of the lever 15 will press downward on the spring 22, which is supported by the collar 23, fixed to the rod 17, and this pressure will assist the weight in operating the valve; the spring preventing injury to the thermostatic device in case through some inadvertence the valve could not be forced downward. Braces 30 fixed to the base prevent buckling of the expansion tube.

A consideration of the apparatus described will show that as the expansion tube expands the outer end of the long arm of the lever 15 will be raised, the weighted arm of the lever 19 will be raised, and the valve 20 will be opened. The lower end of the expansion tube 8 is connected to the boiler below the minimum water level of the boiler by means of the pipes 24; and the upper end of the expansion tube is connected to the boiler at or above the maximum water level by means of the pipes 25 and 26: so that Water from the boiler can pass freely into the lower end of the expansion tube and steam from the boiler can pass freely into the upper end of the expansion tube. As a consequence of this, the water in the expansion tube will at all times be at substantially the same level as the water in the boiler; and hence the upper end of the expansion tube which contains steam will be at the same temperature as the steam, while the lower end of the tube which contains water will be at a lower temperature. Even though the water when it enters the tube may be at substantially the same temperature as the steam, yet it will rapidly radiate heat until it cools to a lower temperature; and as there is no material interchange of the water in the tube and in the boiler, the water in the tube will necessarily, at substantially all times, be somewhat materially lower in temperature than the water or the steam in the boiler. Now it is evident under these circumstances that, as the water-level in the boiler lowers, the water in the tube will be replaced by steam, a greater length of the tube will become of the temperature of the steam, and the tube will expand. As a consequence of this, as the water-level in the boiler lowers the tube will expand and the valve 20 will be opened further than before, and more water will pass into the boiler, offsetting more or less the tendency of the water-level in the boiler to sink. On the other hand, if the load is light, less steam being used, the water-level in the boiler will tend to rise, the tube will receive more water. will become cooler, and will contract; the valve then will be closed more than before and the supply of water will be diminished, so that the tendency of the water in the boiler to rise will also diminish. There will thus be a tendency to maintain somewhat uniform the elevation of the water level. However, by the use of a short expansion tube, or a tube with low coefficient of thermal expansion, or by proper adjustment of the connections between the tube and the valve, the variations in the valve openinqudue to changes in length of the expansion tube, may be made slight; and in case of a heavy load on the boiler the inflow of water may thus be made less than the consumption of water, so that the water in the boiler will sink; and in case of a light load the inflow may be made greater than the consumption of water, and the water will rise. This is so because with an average load, the inflow equals the outgo and the water level is maintained constant; and it but slight changes are made in the valve opening by the thermostatic tube with heavy loads the average inflow would be not very materially increased, so that the inflow would be less than the outflow; and with light loads the inflow would be not materially decreased, so that the inflow would become greater than the outflow.

In order to more fully control this and to properly relate the supply of water to the variable needs of the boiler, a balancedvalve in this instance is used with the regulator. The use of such valve is entirely practicable for the reason that a slight leakage through the valve is immaterial, and

hence a double cylinder valve may be used, such as is indicated in Fig. 2, so that the pressure tending to open the valve will always equal the pressure tending to close the valve. By the use of such a valve, the force required to operate the valve is very materially reduced, and the variations in force required, due to variations in steam pressure or water pressure, are eliminated. So that not only is the action of the valve more uniform, but other disadvantages which accompany the use of the ordinary check-valve, or similar valves, are eliminated. For instance, when changes in load cause changes from contraction to expansion of the tube 8, the force tending to operate the valve changes from an upward pull to a downward push, and, assuming the valve to be an ordinary check-valve closing downward, the pressure on the valve would oppose the operation of the regulator in case of expansion, but assist it in case of contraction. By the use of the balancedwalve, this varying force is entirely eliminated, and as a consequence the position of the valve with reference to the length of the tube is more definite. I have discovered also that a differential valve is sometimes desirable; that is, one in which the rate of opening of the valve varies differently from the rate of motion of the valve cylinder. Also that it is sometimes desirable to use a valve such as may be called a graduated valve; that is, one in which the variations in the opening are by steps or graduated. For instance, if the water is allowed to sink during times of heavy loads, if the load is excessive or is continued for an undue length of time, the amount of water in the boiler may decrease to a dangerous point. To avoid this the valve port is so formed that the port opening increases very rapidly about the time that the water reaches the minimum safe limit, so as to make it impossible for the water to sink below the. danger line.

The specific form of valve port which I prefer is indicated in Fig. 2. The port has a narrow slot 27, which restricts the inflow materially as the valve approaches the closed position, and when desirable will close it entirely, it being understood that the valve as shown in Fig. 2 is closed. The port also has a difiierential portion indicated at 28 which causes the rate of opening to increase materially faster than the rate of motion of the cylinder; and it has an enlarged part 29 which allows the increased flow to eliminate danger of the water sinking below the danger line, by materially increasing the inflow when the expansion tube is heated abnormally.

By the use of this regulator and valve, it will be found that not only is there a continuous feed to the boiler at all times when the boiler is under load, but instead of the variations in feed being co-incident with the variations in steamrequirements. there is a predetermined amount of lag introduced Into the operation of the valve which rc lieves the boiler at times of heavy load. and allows the storage of heat energy during periods of light loads. The arrangement is also such that incase of a very light load or no load the valve will be nearly or entirely closed, and when heavy loads are long continued or excessive, the inflow becomes greater than the outflow and sufficient water to be safe is thereby insured. In case. however. of constant loads not only will the feed be continuous, but it will be constant and equal to the amount of water used.

In practice it has been found desirable to have the bend 31 in pipe 25 as indicated. with pipe 25 slanting downward toward its point of connection with the water column. as shown, so as to drain the condensed water from pipe 2:1 into the boiler-instead of into the expansion tube 8, thus preventing a tendency of the condensed water to increase the temperature or the height of the water in tube 8.

I claim as my invention;

1. The combination of a boiler. a feed water pipe, a balanced valve in said pipe. and a feed water regulator; said regulator being adapted to vary the level of the. water in said boiler and comprising an expansion tube: one end of the operative portion of said tube and the desired maximum water level in said boiler being approximately in the same horizontal plane. and the other end of said tube and the desired minimum 'ater level being approximately in the same horizontal plane: the upper end of said tube being conuectedto said boiler above the maximum water level. and the lower end of said tube being connected to said boiler be low the minimum water level: one end of said tube being rigidly supported. and operating mean connecting the other end of said tube with said valve and in such relation thereto as to supply less water to the boiler than the load requires when the load" is increasing and to supply more water to the boiler than the load requires when the load is decreasing. said relation being such as to hold said valve substantially closed when the water in said boiler is at the maximum level. and to hold said valve open the maximum amount when the water is at the minimum level.

2. The combination of a boiler. a feed water pipe connected to said boiler. a valve in said pipe. and a feed water regulator: said regulator being adapted to vary the level of the water in said boiler and comprising an expansion tube: one end of said tube and the desired maximum water level of said boiler being approximately in the same horizontal plane, and the other end of said tube and-the desired minimum water level being approximately in the same horizontal plane; said tube being connected to said boiler above and below the mean water level; one end of said tube being rigidly supported; and operating means connecting the other end of said tube in such relation with said valve as to begin to supply water.

to said boiler when the water level commences to fall from its maximum level, but in an amount less than that demanded by the load during the first part of the opening movement of the valve and in an amount greater than that demanded by "the maximum load during the latter part of the opening movement of the valve and at the time that the water level has reached its minimum level.

3. The combination of a boiler, a feed water pipe. a valve in said pipe, and a feed water regulator: said regulator comprising an expansion tube; said tube being inclined. and being positioned with the center of the operative portion thereof .in'substantially the same horizontal plane as the mean water level in said boiler; the upper'end of said tube beingconnected to said boiler above the mean water level. the lower end of said tube being connected to said boiler below the mean waterlevel; one end of said tube being rigidly supported, and operating means connecting the other end of said tube with said valve; said tube and said means being arranged so as to commence to open said valve as the level falls from its maximum point. but to supply water to the boiler in an amount less than that demanded by the load on the boiler, and to hold said valve wide open when the minimum water level is reached.

' a. The combination of a boiler. a feed water pipe connected to said boiler, a difl'erential valve in said pipe, and afeed water regulator being adapted to vary the height of the water in the boiler, and comprising an expansion tube; said tube being inclined and being positioned with the center of the operative portion thereof in approximately the same horizontal plane as the mean water level in said boiler. and being operatively connected to said boiler above and below the mean water level therein; one end of said tube being rigidly supported, and operating means connecting the other end .ot'said tube with said valve; the ports in said valve being long and relatively narrow with non-parallel sides, so as to deliver less water to the boiler than the load demands when the valve is first opened by said tube, ut to deliver as much as the maximum load demands when said valve is. fully horizontal plane, the other end of the operative portion of said tube and the desired 7 minimum water level being in approximately the same horizontal plane, the upper end of said tube being connected to said boiler above the mean water level, the lower end of said tube being connected to said boiler below the mean water level, one end of said tube being rigidly supported, and operating means connecting the other end of said tube with said valve, the ports of said valve being of such shape as to supply water to said boiler at a rate less than that demanded by the load as the water begins to sink below its maximum level, but at a rate equal to that demanded by the load if the level sinks to a minimum safe level. said relation being such as to begin to open said valve when the water in said boiler commences to fall from its maximum level, and to hold said valve open the maximum amount when the water is at the minimum level.

6. The combination of a boiler; a feed water pipe connected to said boiler; a valve in said pipe, and a. feed water regulator comprising a tube; said tube being connected to said boiler above and below the average waterlevel therein; said tube being inclined with its central portion substantially in the same plane as the average water level; one end of said tube being rigidly supported, and operating means connecting the other end of said tube in such relation with aid valve as to begin to open said valve when the water level commences to fall fronLits maximum level and to open said valve the maximum amount when the water level has reached the minimum level, but so as to cause the amount of water supplied by said valve to lag behind the outflow when the outflow is varying and to equal the outflow when the outflow becomes constant, whereby for each load on the boiler there is produced a corresponding water level.

In testimony whereof I afiix my signature-

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