US1949437A - Means for controlling the flow of fluids - Google Patents

Description

Patented Mar. 6, 1934 rso srarss ATENT OFFIfiE MEANS FOR CONTROLLING THE FLOW OF FLUIDS 15 Claims.

This invention relates to means for controlling the flow of fluids through orifices and, particularly, the flow of water through valve orifices. One of the objects or" the invention is to provide means for feeding water to boilers, particularly those used. for steam power purposes, in such a manner as to increase the economy of operation and the power capacity of the boiler and the furnace.

The efiiciency of the furnace of a boiler is dependent, to a large extent, upon the rate at which the fuel is consumed, and the maximum efficiency will occur at some definite rate of fuel consumption. Hence, one of the objects of my invention is to maintain substantially constant the most efilcient rate of fuel consumption, it being understood that, in case of batteries of boilers, this is accomplished in part by using more or fewer boilers, according to the amount of steam required. Other objects of the invention will be set forth herein as the method and apparatus of my invention are described.

Of the accompanying drawing, Fig. l is an elevation of a boiler system, comprising feed water regulating means, which embody the features of my invention, portions of the apparatus being in section; and Fig. 2 is an enlarged sectional view of a sylphon bellows which may be used in carrying out my invention.

In order to maintain fairly constant the intensity of the fire in the furnace, it has been usual to provide apparatus for feeding water to the boiler which will maintain substantially constant the water elevation in the boiler when the load on the boiler is substantially uniform, but to vary the Water level elevation as the load varies, ordinarily increasing the elevation as the load decreases and decreasing the elevation as the load increases. When a large quantity of water is fed to a boiler at one time, its steaming capacity is considerably reduced and, in order to maintain the load on the boiler, it is necessary to increase materially the rate of combustion of fuel. To avoid this, it has been the practice to allow the water level in the boiler to sink as the load increases, so as to avoid passing into the boiler an undesirable amount of water.

In order to accomplish this, and for other reasons, I prefer to use a feed water regulator system which comprises a thermostatic tube 5. The tube is mounted on any suitable supporting means, such as the beam 6, and the tube is operatively connected, by a pipe 7, to the steam space of the boiler 4 and, by a pipe 8, to the water space of the boiler, in such a manner that the water level in the tube will be at all times substantially at the same elevation as the water level in the boiler. One end of the thermostat is fixed to the beam 6 and the other end is movably associated therewith and is also connected to a lever 10 which is arranged to operate the feed water valve 15. This is accomplished by means of a link 11 connecting the lever 10 with the lever 12. The lever 12 is fixed to a movable shaft 36, passing into the valve casing 13. Within the casing is an arm 14 also fixed to the shaft 36. This arm is operatively connected with the valve 15.

The valve 15 is mounted in the water supply pipes 30 and 31. The pipe 30 receives water under pressure from any suitable source, and passes it through the ports of the valve 15 and the pipe 31 into the boiler.

In operation, as the water in the boiler is consumed the water level lowers, more steam will pass into the tube 5, and the tube will expand, allowing the long arm of the lever 10 to sink and the weight 32 will thus be able to elevate more the valve 15, thus increasing the flow of water through its ports. As is well understood, this will pass water into the boiler and the water level therein will be prevented from sinking more than is desirable; and, as is understood, theprocess will be reversed when the water in the boiler rises.

The opening further of the ports of the valve 15 and allowing more water therethrough results, ordinarily, in reducing the drop in pressure through the valve, so that it often happens that the flow through the valve is not sufiicient to meet the particular needs of the boiler. It will be understood that boilers are often run in batteries in which all of the boilers are supplied by a single feed water pump, so that the pressure of the water at the inlet of the feed water valve is substantially uniform for all of the boilers and may not be altogetheradapted to each particular boiler. Consequently, it often is desirable to control the drop in pressure through the valve by means depending upon the condition of the individual boiler.

In this invention, I provide for this control by the use of means which tend to prevent a decrease of the drop in pressure through the valve when the flow therethrough is increased, or to prevent an increase in the pressure drop when the how through the valve is decreased. The means which I prefer for this purpose comprise a control valve 16 which, in this instance, is mounted in the same valve casing 13, and the arrangement is such that the water must flow through the ports of this valve before reaching the ports of the valve 15. It will be understood that, with this arrangement, in order to prevent a decrease in pressure drop through the valve 15, it is necessary only to increase the opening of the ports of the valve 16. This, I accomplish in the following manner:

Mounted in the casing 41, which is in communication with the valve casing 13, I provide a difierential pressure motor. In this instance, I prefer to use a sylphon bellows 19. The outer surface of this bellows is subject to the pressure of the water in the chamber 34 and, thus, to the pressure at the inlet of the valve 15. The outlet chamber 37 of the valve 15 is connected, by means of a pipe 29, with the chamber 39, which is in communication with the interior of the sylphon bellows 19. Also, the free end of the bellows 19 is connected to the valve 16 by means of a lever 17 fixed to the shaft 38. This shaft is movably mounted in the casing 41.

As a consequence of this arrangement, when the valve 15 is elevated so as to increase the capacity of its ports, the drop in pressure through the valve 15 will be decreased and, hence, the free end of the sylphon bellows 19 will be elevated, thus forcing the valve 16 upwardly and increasing the capacity of its ports. This will provide greater pressure in the chamber 34, and will thus maintain substantially constant the fall in pressure from the chamber 34 to chamber 37 through the valve ports 15. Attention is called to the fact that both or" these valves are opened by raising the valves.

It will be understood that the pressure inside of the sylphon bellows 19, which is connected to the outlet side of the valve 15, will not change materially, as the pressure on the outlet of the valve 15 is substantially the same as the pressure in the boiler. The only change will be in the increase in pressure drop due to friction in the pipe 31. Hence, the result in the decrease in pressure in the chamber 34 will be to expand the sylphon bellows l9 and this, in turn, will open more the ports of the valve 16 until the pressure in the chamber 34 is restored to balance.

The pressure on the inside of the sylphon bellows 19 being normally less than the pressure on the outside of the bellows, there will be a tendency for the bellows to contract. To restrict this tendency, I provide a lever 18 which is fixed to the shaft 38 outside of the casing 41, and on this is mounted the weight 33. The position of this weight 33 on the lever may be varied, so as to vary as desired the effect of the apparatus in controlling the pressure drop across the ports of the valve 15.

It is sometimes desirable, however, to control the pressure drop through the feed water valve according to the load on the particular boiler. With boilers in batteries, there is often a tendency for the load to swing between certain boilers of the battery dependent on the rate at which the water is being fed to the boilers. If too much water is fed to one boiler, the load will drop off of this boiler and, owing to the greater density of the water, the water level will lower; and, in such a case, the feed water regulator, such as herein described, will still further increase the feed and, thus, further decrease the load until a large portion of the load has been removed from this boiler and transferred to others.

For this and other reasons, I have found it ad- I visable sometimes to increase the feed to the boiler as the load increases, and to decrease the feed when the load decreases, at rates greater than that provided for by the automatic feed water regulator. While I have already described one method by which I accomplish this, I also provide another method. Either of these methods may be used independently or" each other, or both may be used together. For simplicity, I have illustrated apparatus for carrying out both methods simultaneously.

If the load on a boiler is increased, there will be a tendency for the steam pressure in the steam main of that boiler to decrease. For instance, the pressure at the point 28 in the steam pipe 2'7 will decrease somewhat as the load on the boiler increases. To make this more pronounced, however, I prefer to provide in this pipe a restricted orifice 26. With this orifice, in case of an increase in load, the pressure drop through the orifice 26 will be increased and there will be less pressure at the point 28. In order to take advantage of this increased drop in pressure through the orifice 26, I connect the pipe 27 with a casing 22 by means of the pipe 25, so that the variations in pressure at the point 28 are transmitted to the interior of the casing 22. In this casing, I mount a sylphon bellows 24, the interior of which also communicates with the chamber 39. In case of an increased load, as the pressure drop through the orifice 26 increases, there will be a lowered pressure in the chamber 22, and the sylphon bellows will therefore tend to expand. In order to take advantage of this expansion, the free end of the bellows is connected, by means of an arm 23, to a movable shaft 40 in the casing 22, and a lever 21 and a link 20 connect the shaft 40 with the lever 18. Hence, as the bellows 24 expands, the arm 21 will tend to pull downwardly the arm 18 and to open more the valve 16 until the pressure in the chamber 34, acting on the sylphon bellows 19, is sufficient to restore the balance.

Although the valve 16 will open wider as the load increases, yet it will not open at a sufficient rate to supply water as fast as the water is fiowing from the boiler, so long as the load is in creasing. As a consequence, when the heavy load becomes constant, the water will be lower than it was before the load began to increase.

Owing to the fact that the fiow through an orifice varies as the square root of the pressure drop across the orifice, the control of the feed by means of the pressure change across the orinos 15 is limited to rather nominal changes in load, as it is necessary to maintain the pressure in the pipe 30 sufficiently high to take care of the maximum demand, and it is undesirable to have this pressure greatly in excess of the boiler pressure; so that the control of the feed to the boiler by means of the pressure change through the orifice 26 is limited to a certain range in load. For any other range, the flow of feed water to the boiler is controlled by the feed water regulator.

It will thus be seen that, by means of the apparatus which I provide in carrying out my method of controlling the feed of water to the boiler, the feed is controlled normally by means of a feed water regulator in an ordinary manner. But, in order to prevent undesirable variations in the pressure drop through the feed water valve by this method of regulation, I have provided means for opposing changes in the pressuredrop, owing to changes in the opening of the feed water valve; and the means which I provide may depend upon the actual drop through the valve itself or may depend upon variations in pressure in the steam main of the boiler, or may depend upon both of these factors simultaneously. However, I do not desire to belimited to the particular means which I have illustrated for carrying out my invention, as other apparatus could be used, such as float feed water regulators; and various modifications could be made in the apparatus which I have disclosed, by those skilled in the art, without departing from the spirit of my invention as disclosed by the following claims. 1

I claim as my invention:

1. In a steam boiler system, a feed-water valve, and means continuously aflected by variations in the load on the boiler and by the pressure drop through said valve for affecting the flow of water through said valve.

2. In a steam boiler system, a water pipe adapted to receive and transmit water under pressure, a casing connected in said pipe, a chamber in said casing, a partition across said chamber, a main and a control valve in said partition, means for varying the opening of said main valve, means depending on the drop in pressure through said main valve for varying the opening of said control valve, and means continuously depending on the pressure variations in the boiler main for varying the opening of said control valve.

3. In a steam boiler system, having a steam main, the combination of a water conduit, a main valve and a control valve mounted in said conduit, a sylphon bellows for operating said control valve, communicating means connecting one side of said sylphon bellows with the inlet of said main valve, communicating means connecting the other side of said bellows with the outlet of said main valve, a second sylphon bellows, communicating means connecting one side of said second bellows with the outlet of same main valve, and communicating means connecting the other side of said second bellows with said steam main, said second bellows being operatively associated with said control valve.

4. In a boiler system, having a steam main and a fluid control system, comprising, a valve, and means for controlling the drop in pressure of the fluid passing through said valve, said means including a fluid operable motor, said motor being operatively associated by fluid communicating means with both sides of said valve, a second fluid operable motor, said second motor being operatively associated by fluid communicating means with one side of said valve and with said main and being operatively associated with said first mentioned motor.

5. A boiler system, comprising a steam main, 2. feed-water valve, means actuated by variations in pressure drop through said valve tending to maintain constant the said pressure drop, and means actuated by the steam pressure in said main continuously tending to vary the pressure drop through said valve in proportion to the said steam pressure.

6. In a steam boiler system having a steam main, the combination of a water conduit, a main valve and a control valve mounted in said conduit, a fluid operable motor for operating said control valve, communicating means connecting said motor with the inlet of said main valve, a second fluid operable motor, communicating means connecting both of said motors with the outlet of same main valve, and communicating means connecting the said second motor with said steam main, said second motor being operatively associated with said control valve.

7. In a steam boiler system having a steam .main anda feed water valve, means responsive to the differential fluid pressures in the inlet and outlet of the valve and also to the differential in fluid pressure in the main and the valve outlet, for affecting the flow through the valve, independently of the valve opening.

8. In a boiler system having a steam main, a fluid feed control system comprising a supply pipe and a feed valve mounted in the pipe, and means forcontrolling the drop in pressure of the fluid passing through the valve, said means comprising a fluid pressure operable motor, and a control valve mounted in the pipe and operatively connected with the motor, said motor being directly connected by means transmitting fluid pressure to the motor directly from the main and from the outlet of the feed valve, the respective fluid pressures thereby produced in the motor tending to move the plunger of the control valve in opposite directions.

9. In a boiler system having a steam main, a water supply pipe, a feed valve mounted in the pipe, and means forvarying the drop in pressure through the valve without varying its opening, said means comprising a fluid pressure operable 'motor having an operating chamber, a conduit providing direct communication between the main and the chamber so as to increase the fluid pressure in the motor chamber as the pressure in the main increases, said motor also being operatively associated by fluid communicating means with the outlet of the valve, the two fluid pressures thus effective in the motor being arranged to oppose each other in the motor.

10. In a boiler system, a steam main, a feed water pipe and a feed valve mounted therein, and means for controlling the drop in pressure through the valve, said means including a fluid pressure operable motor, and a second valve mounted in the pipe and operatively connected with the motor, said motor being directly connected by fluid communicating means with the main and with the inlet of the feed valve, the fluid pressures thereby produced in the motor tending to move the plunger of the second valve in the same direction, and yielding means opposing said movement.

11. In a boiler system, a steam main and a Water supply main, a valve in the water main, and means for controlling the drop in pressure of the water passing through the valve without varying the valve opening, said means including a fluid operable motor, and a conduit providing direct communication between the motor and the main and between the motor and the valve inlet, so as to increase the fluid pressure in the motor as the pressure in the main or the inlet increases, said pressures acting cumulatively to operate the motor.

12. In a boiler system, a water supply pipe, a feed water valve in the pipe, a steam main, and means for controlling the drop in pressure through the valve, said means comprising a fluid pressure motor having an operating chamber, a pipe providing direct communication between the chamber and the main, a conduit providing communication between the motor and one side of the valve, a second valve in the pipe, said motor being operatively connected with the second valve.

13. In the art of flow control, the method which comprises continuously producing an effect representative of rate of flow of efiluent from a reservoir, continuously producing an effect representative of the difference between the pressures on opposite sides of a variable orifice in the path of fluid supplied to the reservoir, and varying the pressure on the supply side of the orifice to continuously balance the efiects independently of the area of the variable orifice.

14. In the art of flow control, the method which comprises continuously producing an effect representative of rate of flow of efiluent from a. reservoir and which varies directly as the rate varies, continuously producing an effect represen-

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