US1674456A - Boiler-feed-water-regulating apparatus - Google Patents

Description

Patented June 19, 1928.

UNITED STATES CHARLES H. SMOOT, F MAPLEWOOD, NEW JERSEY.

BOILER-FEED-'WATER-REGULATING APPARATUS.

Application led February 15, 1927. Serial No. 168,447.

My .invention is concerned with the control of the feed water in boiler p-lants and consists in automatic means for regulating the supply of water to the boilers that insures efficient and safe steam generation at all times.

The advent of the modern practice of operating boilers under widely varying loads and at higl'i .pressures and high degrees of superheat has made the problem of the feed water control of paramount importance. The constant excess pressure regulator which supplies a constant flow of feed water to the boilers by holding constant the diffe-rence between the pump discharge pressure and that within the drum is only eilicient for boilers operating at constant rating while the usual water level regulator alone is only efficient for small variations in load.

I have devised apparat-us that is adapted to vary the supply of feed water to the boiler drum in proportion to the rating or load by a regulation of the excess feed water pressure by a balance of a function of the boiler rating against such excess pressure. I1`urthern'1o1e, l have devised a novel water level regulator free from moving parts and of simple construction which is arranged to act as a micrometer adjustment to my excess pressure regulator. My invention `further provides means which, during or immediately following a sudden changel in load acts to temporarily vary the feed water supply in a direction opposite to that. in which t-he change in load occurred and in which the feed water supply will finally be effected. By this arrangement a sudden rush of comparatively cold water into the boiler drum is prevented during sudden increase in load and allowed during sudden decrease in load in each case aiding the furnace and boiler to become .adjusted to the new demands.

For a better understanding of my invention and the advantages pertaining'thereto, reference should be had to the accompanying drawing in which I have illustrated diagrammatically oneembodiment of my invention. Referring to the drawing, the drum 1 of a boiler furnace 2 is supplied with feed water from a conduit 3 by the pump 4. The pump 4 is driven by an engine 5 receiving motive fluid through pipe 6 and controlled through throttle 7 by regulating apparatus hereinafter tobe described. The

drum 1 is shown as connected to the main' steam header 8 through a superheater 9.

The regulating apparatus consists essentially in a pivoted lever 10 which is acted upon by various forcesall of which are functions of the feed water supply or of the furnace rating or load. In response to an unbalance of these forces the lever 10 effects the regulation of the throttle 7 through a leakage port 11 and auxiliary power device 1 At 13 is a device which transmits to the lever 10 the differential between the pump discharge pressure as measured at 14 and the pressure within the drum 1. The pressure at 14 is transmitted through pipe 15 to a chamber 16 one side of which is closed by a. diaphragm 17 and the pressure in the drum 1 is transmitted through pipe 18 to a chamber 19 closed by a diaphragm 20. A rod 21 rigidly attached at one end toy the diaphragm 17 and at the other end to the diaphragm passes through a cross beam 22 to which it is held by nuts 23. Attached to the beam 22 are two upright rods `24 which are interconnected above the chamber 16 by a. second cross beam 25 and which terminate in enlarged' end portions 26. The beam 25 is held in place on the upright rods by springs 27 interposed between the beam and the ends 26 forcing the beam against nuts 28. A rod 29 connects the beam 25 with the lever 10 and transmits to the lever a downward pull equal to the excess feed water pressure as measured by the difference in the pressures upon the diaphragms 17 and 20. The springs 27 are of such strength that they are not appreciably compressed by this excess pressure and during normal operation of the system can be considered as rigid bodies. The function of these springs is to protect the apparatus in case the downward pull through the rods 24 becomes excessive as by the breaking of p-ipe 18. For this purpose a stop 30 is provided which limits the travel of the beam 25 and rod 29 and permits further downward movement of rods 24 to occ-ur only by compression of the springs 27.

At 31 is adevice which ip the specific arrangement illustrated exerts a steady downward push upon the lever 10 during steady load and upon an increase in load operates to'momentarily decrease this force and subsequently, if the new load becomes steady, to

increase this force until it reaches a value greater than thatbefore the load changed; the difference ifn thefsteadyfiorces before and aftei' theload change having a definite relation to the load change. Conversely, with a decrease in load the device 31 irst increases and then decreases the force upon the lever 10. The device 31 consists in three chambers 32, 33 and 34, two of which, 32 and 33, are partially filled with a heavy liquid, such as glycerine and are connected together below the level of the liquid through a small port, shown .at 35, the slze of which may be adjusted by a. screw 36. The third chamber 34 is free from liquid and is "not in communication with either of the other two except as both chambers 33 and 34 are connected to a conduit 37. The conduit 37 transmits to both chambers 33 and 34 simultaneously a controlling pressure which is preferably arranged .to vary automatically with the load or rating.

In the particular arrangement illustrated the pressure within the pipe 37 is controlled to vary inversely with the steam pressure in the header 8 by apparatus hereinafter to be described. The chamber 32 is closed on one side by a diaphragm 38 to which is attached a rod 39 and the chamber 34 is closedby a diaphragm 40 to which is attached a rod 41. Each diaphragm transmits through the rod attached thereto,`the pressure exerted upon it by the enclosed liquid or air to a lever 42 which is pivoted at 43 and linked tno lever 10 through rod 44. The pivot 43 1s placed nearer to t-he point at which the rod 41 pushes upon the lever 42 than to the point of contact between rod 39 with the lever, with the result that equal pressures upon the diaphragms 38 and 40 tend to turn the lever 42 in a counter clock wise direction, thus the new value of the load. This pressure difference Will gradually vanish as the new load becomes steady. The time taken for the equalization of these pressures depends upon the setting of the screw 36. The element 31 forms no part of my present 1nvention except as to its particular application to the feed Water control as it is described and broadly claimed in my copending-application Serial Number 103,182, filed April 19, 1926.

At 45 is a closed vessel forming part of my new water level regulator. The vessel 45 is continuously fed with water from a pipe 46 leading from the feed water pipe A partition 47 divides the-'lowerfpartof t-he vessel into two chambers, the water space of one of which is connected through pipe 48 with the wateiyspace of the drum 1; the water space of the other chamber being connected'through pipe -49 with a chamber 50. The common space above the partition is in communication with the steam space of the drum 1 through pipe 51. A valve 52 in the feed pipe 3 permits adjustment of the amount of water luy-passed through the vessel 45. In operation the setting of the valve 52 is such as to insure a supply of water to the vessel 34 sufficient to flow over the partition 47 and thus to maintain a constant water level in the part of the vessel in communication with chamber 50. A pipe 53 eonnects the water space of the drum 1 with a chamber 54 which chamber is separated by a diaphragm 55 from the chamber 50. The pressure within the chamber 54 varies with the height of the water and with the pressure of the'steam in the drum 1 while the pressure in the chamber 50 varies with this steam pressure only as the height of the water in communication with this chamber is always that of the partition 47. The differential pressure therefore tending to move the diaphragm 55, depends only upon the difference between the level of the water in the drum 1 and the fixed level of the water in the vessel 45. This differential pressure is transmitted to the lever 10 through a rod 56 attached to the diaphragm 55 and operates to adjust the regulat-ion when the level of the water within the boiler drum varies from the desired value.

The position of the lever 10, which is determined by the excess pressure acting through the device 13,'by the load acting through the device 31, and by the water level in the drum acting through the diaphragm 55, itself determines the leakage through the port 11 and so controls the ressure exerted upon `a piston 57 by an auxiliary fluid such as oil or steam which enters the regulator 12 through a restriction 58 in asupply pipe 59. The pressure upon the piston 57 moves the piston against the opposing force of a spring 60 and eects the control of the throttle 7 by means of a lever 61 as shown.

Controlling pressure is delivered through pipe 37 to the device 31 from a chamber 62 which is provided with a port 63 and which receives air under pressure from a pipe 64. A cup valve 65 covers the port 63 and is held in position by a weight 66 acting through a lever 67. The force of the weight 66 tending to close the port 63 is opposed by the pressure of the steam in achamber 68 acting upon a diaphragm 69, as well as by the pressure of the air within the chambers 62 acting upon the valve 65. The chamlll() ber 68 is in communication with the steam main 8 through a conduit 70. A branch 71 provided with a valve 72 permits leakage to the atmosphere and a valve 7 3 in the pipe 37 permits adjustment of the ratio of the pressure at31 to that within the chamber 62.

' Upon change in load, the pressure in the header 8 will vary, and consequentlv the lever 67 and valve (35 will be correspondingly shifted to permit more or less leakage through port. 63 until the pressure of the air in the chamber ($2 acting upon the valve 65 balances the difference between the forces due to the weight 66 and to the steam pressure acting upon diaphragm (if). The pressure delivered to the device 31 is thus maintained an inverse function of the steam pressure. The particular arrangement illustrated forms no part of my present invention, it being merely a. simplified representation of the principles embodied in the master controller described and claimed in my Reissue Iatent #16.507, dated Dec. 21, 1926. It is immaterial to my present invention which of the variations which occur with changes of load, whether directly resulting therefrom or indirectly as a result of either manual or automatic control of combustion, is employed to produce the force to balance that due to the excess feed water pressure. Any such suitable variation is included within the expression function of boiler rating as that term is employed herein and in the claims.

Assuming now that the lever 10 is in its neutral position with a constant load upon the boiler and a definite excess feed water pressure delivered by the pump, the leakage through the port 11 will be such as to maintain stationary the piston 57. If now for any reason the pump delivers less pressure than before the pressure in the chamber 16 will decrease, resulting in a decrease of the pull transmitted through rod 29 to the lever 10. The forces on the lever will then become out of balance and the lever Will move to decrease the leakage through port 11 and to thereby open the throttle 7 until the pump has been speededup to return the discharge pressure to that desired. If, instead of the excess pressure, it is the load that decreases, then the first effect will be a decrease in the pressure upon the diaphragm 40 with a consequent increase in the downward push transmitted through rod 44 to lever 10and a resulting temporary speeding up of the engine 5 and pump 4 to supply more water to the boiler drum. If the load. now remains at this lower value, the pressure upon the diaphragm 38 will gradually decrease as liquid leaks through the port 35 into the chamber 33, and the, final effect when the pressures Within the chambers 32 and 34 have become equal is a reduction in the downward push upon the lever 10 in proportion to the load decrease, resulting in a slower speed of the pump 4 and a proportionate reduction in the feed Water flow. This feature of my apparatus permits rapid adjustment of the boiler furnace to sudden changes in load, for when a sudden demand for steam occurs the temperature of the water in the boiler is more quickly raised to the boiling point if the supply of fresh water is temporarily reduced until the combustion in the furnace has had an opportunity to be increased sailiciently to handle the new demands. Similarly with a sudden reduction in load the reduction in steam production desired is aided by the temporary increase in the water supplied to the drum with its consequent temperature reduction. If at any time the level in the boiler varies from that desired, the differential pressure upon the diaphragm 55 independently adjusts the regulation of the feed water pressure.

The entire apparatus thus operates to supply a definite excess feed water pressure with each load upon the boiler, a greater load corresponding to a greater excess pressure; to momentarily decrease or increase the excess pressure while the load increases or decreases respectively; and to maintain a constant level of water within the boiler drum.

The adjustment of the regulation afforded A other types of water level regulators could be used but I prefer the one described for its simplicity and reliability.

My invention is not limited to the specific embodiment illustrated either as to the arrangement or as to the construction of the various elements, and parts of my invention can be advantageously used if desired without the corresponding use of other parts.

In the particular embodiment illustrated the regulation is effected by the control of the speed of the feed Water pump but it 1s of course immaterial whether the actual element controlled be the pump or a valve in the feed water supply line.

It will be apparent to those skilled in the art that my invention is equally applicable whether one or a plurality of boilers are supplied by the feed water pump. In the case when a plurality of boilers are supplied by a single pump it is purely a matter of choice as to how much, if any, of the tial pressure device for measuring the `excess feed Water pressure, a device respon-V sive to a force which is a function of the boiler rating, means for subjecting said balance to the opposing actions of said vdevices, and means for controlling said excess pressure by said balance.`

E2. Apparatus as in claim 1 including means responsive to variations of water level in the boiler and effecting adjustment of the regulation.

3. In a boiler plant, a feed water regulator including relative quick acting means acting to decrease and increase the water supply during periods of increasing `and decreasing loa-d respectively and relatively slower acting and more powerful means acting to increase and decrease the water supply with increase and` decrease respectively in the load.

4. In a boiler plant, a feed water regulator, including in combination a bala-nce, means for acting upon it by a force varying with the excess feed Water pressure, means for acting upon it by a second force which is the resultant of opposing forces, and relatively rapid and slow acting means each responsive to variations in a function of the boiler rating for creating such opposing forces.

5. Apparatus as in claim` 4 including means for effecting an automatic adjust' ment of the regulation by apparatus responsive to changes of water level in the boiler.

6. In a boiler having a water and steam drum and a feed water supply pipe leading thereto, the combination comprising a regulator for varying the feed 'water to said tor for v the www;

boiler drum in accordance with the load, a vessel in communication`with the steam space of the boiler drum and also with the feed water pipe, a partition in said vessel extending td 'a V level higher than `that of the water in the drum, avalve in said feed pipe for ley-passing water to said vessel in amounts sufficient to cause a continuous flow over said partition, a pipe connecting the vessel with the water space of the drum for draining the water from said vessel and a device responsive to the difference in level of said partit-ion and of the water in said drum for adjusting said feed water regulator.

7. Apparatus for controlling the excess feed water pressure including a pivoted lever subjected at one end to the excess feed water pressure and at the other end to a force which varies with the load in such a way that. as the load increases from one steady value to a second steady value, said force first decreases and then increases by an amount proportional to said load increase, and means for controlling said excess pressure by said lever.

8. In a boiler plant, the combination in a water feed regulator, of a regulating member operatively related withthe Water supply-means to vary the rate of supply by -its movement, and means for controlling such movement in accordance with the resultant of forces, two being opposite to each other and created by relatively slow and quick acting apparatus responsive to variations in a function of the boiler rating, and two others being created by apparatus responsive respectively to the pressure of the water supplied and the pressure Within the boiler drum.

In testimony whereof, I have signed my name to this specification.

CHARLES H. SMOOT.

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