US3415262A

US3415262A - Aspiration elimination for diverting valves

Info

Publication number: US3415262A
Application number: US500939A
Authority: US
Inventors: William C Chatman
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1965-10-22
Filing date: 1965-10-22
Publication date: 1968-12-10
Anticipated expiration: 1985-12-10

Description

Dec. 10, 1968 w. c. CHATMAN ASPIRATION ELIMINATION FOR DIVERTING VALVES Filed Oct. 22, 1965 INVENTOR Wizlz'an 6'. 6mm;

BY field ,4 mm,

IQTI'ORNEYS United States Patent ABSTRACT OF THE DISCLOSURE A fluid diverting valve for selectively diverting fluid in which the adverse affect of aspiration generated in the valve is substantially prevented. A portion of the main fluid is continuously conveyed to a source of ambient fluid to substantially prevent entrainment of the ambient fluid with the main fluid.

Fluid diverting valves which will permit the switching of a stream of fluid into different outlet conduits without the assistance of moving parts within the valve have become well known in the prior art. The stream of fluid is fed under pressure into the valve through a power nozzle forming a power jet or main stream. The main stream is directed into an interaction chamber having a plurality of outlet ports radiating from the side of the chamber opposite the power nozzle. Either a system of fluid control jets, known as stream interaction control or a system for controlling the pressure distribution in the boundary region of the main stream, known as boundary layer control, serves to direct the main stream into the desired outlet port.

In the stream interaction system control jet nozzles are properly situated radially with respect to the power jet with the nozzles directed towards the power jet. Upon actuation of any one of the control jets a relatively small stream of fluid is directed against the side of the main stream deflecting the main stream away from the control jet. It may be readily seen that it is possible to divert a high power jet into the desired outlet port with a low power control jet.

In the boundary layer control system the configuration of the side walls of the interaction chamber is critical and with proper design it is possible to cause the main stream to lock-on to a side wall adjacent the outlet port into which the main stream is directed. Fluid control jets similar to those used in the stream interaction system serve to initially divert the main stream into any one of the desired outlet ports, the main stream locking-on to the side wall in each position. Once the main stream has locked-on to the side wall, it will remain in that flow configuration without the further assistance of the control jet. Thus, control jets are required only to initially divert the main stream to a different position and a diflerent outlet port and need not continue to operate once the new flow configuration has been established.

The main stream passing through the interaction chamber to one of the outlet ports entrains ambient air in the chamber thus requiring that the ambient air be continuously replenished. Replenishing air is commonly drawn into the chamber from outlet conduits not in use by the vacuum created as the air adjacent the main stream is entrained and carried away with the main stream through the outlet port. This phenomenon, called aspiration, has certain drawbacks when certain types of fluid are passing through the diverting valve. For example, if the fluid reacted on contact with air, or a mixture of the fluid and air were highly combustible, serious consequences are possible. Because of this, it has been impractical to use fluid diverting valves with some types of fluids.

It is therefore, an object of this invention to provide means whereby fluid diverting valves of the kind described above may be used with all types of fluids.

Another object of the invention is to provide means whereby the flow of replenishing air drawn through the outlet conduits as a result of the aspiration eflect is reduced or eliminated.

The above and other objects of the invention will become apparent in the following detailed description of one embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a partial sectional plan view of a conventional fluid diverting valve of the stream interaction control type;

FIGURE 2 is a partial sectional plan view of a conventional fluid diverting valve of the boundary layer control type; and

FIGURE 3 is a partial sectional plan view of a fluid diverting valve according to the present invention.

Referring now to the drawings, FIGURE 1 shows a conventional two-way diverting valve 1 in which fluid enters the valve through conduit 2 and passes through power nozzle 4. Situated immediately beyond the power nozzle 4 is an interaction chamber 6 in which are located two control nozzles 8, 10 on opposite sides of the valve and at substantially right angles with respect to the central axis of the power nozzle 4. The end of the interaction chamber 6 directly opposite the power nozzle 4 contains a splitter 12 and two

outlet ports

14, 16 connected to

dis charge conduits

18, 20.

Control valves

22, 24 in

pipes

26, 28 connected to control nozzles 8, 10 serve to regulate the control jets as desired.

The operation of the diverting valve is quite simple. Fluid is constantly flowing into the valve through inlet 2 and power nozzle 4. When neither of the control jets are in operation the fluid flow will be divided into equal portions by splitter 12, the two portions of the fluid flow passing through

outlet ports

14, 16 and

conduits

18, 20. By opening valve 22 fluid under pressure is projected in the form of a jet against the side of the main stream in the interaction chamber causing the fluid to be diverted towards outlet port 16 and conduit 20. With suflicient flow from the control jet the main stream will be diverted such that there will be no fluid flow through outlet port 14 and conduit 18. By the same token, when valve 22 is closed and valve 24 is opened, a control jet passing through nozzle 10 will divert the main stream into outlet port 14 and conduit 18.

FIGURE 2 is in many respects similar to FIGURE 1 and like parts have been given the same numerical designation. The major difference with respect to the valve shown in FIGURE 2 which is of the stream interaction type is that the interaction chamber 6 is appropriately shaped for reasons which will become apparent later.

Valves

22, 24 and

pipes

26, 28 have been eliminated and in their place are

supply passage ways

30, 32 which are covered by pivotally mounted

flapper valves

34 and 36.

With this arrangement the main stream is diverted by opening one or the other of the

flapper valves

34, 36. When flapper valve 34 is opened the vacuum created by entrainment of ambient air in the main stream will generate an air stream through supply passage way 30 causing an increase in air pressure on that side of the main stream relative to the opposite side, and thus divert the main stream towards outlet port 16 and conduit 20. Conversely, when flapper valve 34 is closed and flapper valve 36 is opened, an air flow will be generated in supply passage 32 causing the main stream to be diverted into outlet port 14 and conduit 18.

The interaction chamber 6 must be properly designed to permit the creation of this pressure differential in the boundary layer surrounding the main stream. The air pressure created by the entrainment of air is considerably more on the side of the main stream on which the flapper valve is open; while the air pressure on the side of the power jet on which the flapper valve is closed is considerably less, thus causing the diversion of the main stream in the direction of the lowest ambient air pressure. Once the power jet has been diverted, the pressure differential between the opposite sides of the power jet will remain constant even though the flapper valve which had been opened to cause diversion in the main stream is closed. Thus, once the main stream has been diverted into outlet port 14 and conduit 18, the flapper valve 36 may be closed. Ambient air will continue to be supplied to the high pressure side of the main stream through unused outlet port 16. The high vacuum side of the power jet then lies near the outside wall of the interaction chamber 6 adjacent the outlet port 16 and after flapper valve 34 is again closed an aspirated flow of ambient air will be drawn towards the main stream through unused outlet port 14 and conduit 18.

The aspiration of ambient air through the outlet port not in use, which is characteristic of both types of diverting valves (FIGS. 1 and 2), has certain disadvantages when particular types of fluid are passing through the diverting valve. When high temperature regeneration gas containing carbon monoxide is the fluid being passed through this valve, it has been found that when 100 percent of the gas flow is going through one of the channels, ambient air flow equalling approximately 5 percent will flow in a reverse direction through the other channel. In the design of a diverting valve of this type, it is impossible to obtain the exact geometry which is required to eliminate aspiration or back-flow unless one is willing to settle for a small amount of leakage through the other outlet port which frequently would also be a disadvantage. One may readily understand that a 5 percent mixture of ambient air with carbon monoxide in a conduit would present a serious problem since afterburning in the conduit with attendant drastic temperature increases would be the result. The materials needed for construction of a conduit capable of withstanding the high temperatures resulting from afterburning would be costly thus making the use of this type of diverting valve, as a practical matter, impossible. The aspiration affect could be eliminated by use of a butterfly valve in the conduit not in use; however, this again increases the cost of producing the valve substantially.

The present invention as shown in FIGURE 3 is a simple and economically sound method of eliminating, or at least substantially reducing, the amount of aspirated air flow through the unused outlet port. In FIGURE 3 which shows the present invention applied to the diverting valve of FIGURE 1, parts common with FIGURE 1 have been given the identical numerical designation. Added to the diverting valves shown in FIGURE 1 is a controlled bypass conduit 38 leading from the inlet conduit 2 to the outlet conduit 18. Fluid flow is controlled in this bypass conduit by a valve 40. With this arrangement, while the main stream is diverted into outlet port 16 and conduit 20, a controlled amount of the same fluid is permitted to flow from inlet conduit 2 through bypass 38 into the unused outlet conduit 18 where it is drawn by the aspiratin g affect caused by the main stream described previously towards the interaction chamber 6. When the fluid from the bypass reaches the boundary layer adjacent the main stream, it is entrapped in the main stream flow.

By manipulation of valve 40, it is possible to control the amount of fluid which is to be cycled into the aspiration flow. Theoretically, it should be possible to have sufiicient bypass flow such that all of the aspirated flow towards the power jet is in the form of fluid from the bypass; but certain disadvantages may result from this, and therefore it is preferred that the bypass flow be slightly less than the volume required for the aspirated flow. Under these conditions, the bypass flow upon reaching the unused outlet conduit will mix with a small amount of air drawn through the outlet conduit and the mixture will flow towards the main stream where it becomes entrained.

Considering this improvement in a specific situation, if carbon monoxide is the fluid flowing through the diverting valve of FIGURE 3 and the aspirated flow entrapped by the main stream amounts to 5 percent of the total fluid flow through the interaction chamber, then the bypass conduit 38 may be set by adjustment of valve 40 to permit 4 /2 percent of the total carbon monoxide entering the diverting valve to be channeled into the outlet circuit 18 where it will combine with one-half percent air drawn through the outiet conduit 18, making a total of 5 percent fluid flow through outlet port 14 towards the interaction chamber 6. With this arrangement, the material flowing back through the unused outlet port is predominantly the same material as is passing through the diverting valve with 90 percent of the aspiration requirement being met by the flow through the bypass conduit. With this arrangement the amount of afterburning is within tolerable limits. If the bypass flow is increased to more than 90 percent of the aspiration requirement, then afterburning is virtually eliminated.

The arrangement of the bypass conduit shown in FIG- URE 3 as is applied to the device shown in FIGURE 1 is equally suited for use with the modified diverting valve shown in FIGURE 2. It is important, particularly with respect to the boundary layer type diverting valve of FIG- URE 2, that the bypass conduit flow not interfere with the critical boundary layer pressure differential. The inlet to the bypass conduit must be an adequate distance upstream from the power nozzle 4 to avoid any interference with fluid flow through the power nozzle. Also, the outlet of the bypass conduit must be sufficiently beyond the interaciton chamber 6 to avoid any interference with the pressure differential therein. The flow of fluid through the bypass conduit must be carefully controlled since a bypass fluid flow equivalent to more than aspiration demands may easily upset the boundary layer pressure diflerential in the interaction chamber.

It may be readily understood that more than one controlled bypass conduit may be incorporated in a single diverting valve. Thus, the valve shown in FIGURE 3 may have a second bypass arrangement on the side of the valve opposite the one shown in the figure. With this additional bypass, it is possible to reduce or eliminate the aspirated flow of air in outlet conduit 20 when the main stream is directed into outlet port 14. It is important, particularly in a diverting valve having a plurality of bypass conduits, that the bypass conduit leading to the outlet conduit into which the main stream is directed be closed in order not to interfere with the boundary layer pressure differential.

With the above description and illustration of one specific embodiment of the present invention, it should be clear that variations and modifications of the details of construction specifically illustrated and described may be resorted to without departing from the direct spirit and scope of the present invention.

What I claim is:

1. A fluid diverting valve comprising an interaction chamber, a power nozzle for issuing a main fluid stream at one end of said interaction chamber, an inlet conduit connected to said power nozzle, the opposite end of said interaction chamber having a plurality of outlet ports positioned to receive said main fluid stream, outlet conduits connected to each of said outlet ports, a plurality of control nozzles for selectively issuing control fluid streams directed agianst said main stream in said interaction chamber whereby said main stream may be displaced into any one of said outlet ports, and at least one bypass conduit connecting said inlet conduit with one of said outlet conduits whereby a portion of said main fluid stream may be conveyed from said inlet conduit into said outlet conduit to substantially prevent entrainment of the ambient fluid in said interaction chamber aspirated by said main fluid stream.

2. A fluid diverting valve comprising an interaction chamber, a power nozzle for issuing a main fluid stream at one end of said interaction chamber, an inlet conduit connected to said power nozzle, the opposite end of said interaction chamber having a plurality of outlet ports positioned to receive said main fluid stream, outlet conduits connected to each of said outlet ports, a plurality of valve controlled passages adjacent said main fluid stream communicating with the atmosphere for initiating a pressure differential in the boundary layer surrounding said main fluid stream whereby said main stream may be displaced into any one of said outlet ports, and at least one bypass conduit connecting said inlet conduit with one of said outlet conduits whereby a portion of said main fluid stream may be conveyed from said inlet conduit into said outlet conduit to substantially prevent entrainment of the ambient fluid in said interaction chamber aspirated by said main fluid stream.

3. A fluid diverting valve comprising an interaction chamber, a power nozzle for issuing a main fluid stream at one end of said interaction chamber, an inlet conduit connected to said power nozzle, the opposite end of said interaction chamber having two outlet ports positioned to receive said main fluid stream, outlet conduits connected to each of said outlet ports, two control nozzles on opposite sides of said main fluid stream in said chamber for selectively issuing control fluid streams directed against said main stream whereby said main stream may be displaced into either of said inlet ports, and bypass conduits connecting said inlet conduit with each of said outlet conduits whereby a portion of said main fluid stream may be conveyed from said inlet conduit into either of said outlet conduits to substantially prevent entrainment of the ambient fluid in said interaction chamber aspirated by said main fluid stream.

4. A fluid diverting valve comprising an interaction chamber, a power nozzle for issuing a main fluid stream at one end of said interaction chamber, an inlet conduit connected to said power nozzle, the opposite end of said interaction chamber having two outlet ports positioned to receive said main fluid stream, outlet conduits connected to each of said outlet ports, two valve controlled passages on opposite sides of said main fluid stream in said chamber communicating with the atmosphere for initiating a pressure differential in the boundary layer surrounding said main fluid stream whereby said main stream may be displaced into either of said outlet ports, and bypass conduits connecting said inlet conduit with each of said outlet conduits whereby a portion of said main fluid stream may be conveyed from said inlet conduit into either of said outlet conduits to substantially prevent entrainment of the ambient fluid in said interaction chamber aspirated by said main fluid stream.

5. In a fluid diverting valve for selectively diverting fluid, a fluid interaction chamber having an inlet and a plurality of outlets, one of said outlets connected to a source of ambient fluid, means for ejecting a main fluid stream through said inlet into said chamber, and means for selectively diverting said main fluid stream into one of said outlets, means circumventing said interaction chamber for continuously conveying a portion of said main fluid stream from said inlet to said source of ambient fluid to substantially prevent entrainment of said ambient fluid with said main fluid stream in said outlet.

6. A fluid diverting valve according to claim 5 in which said means for selectively diverting said main fluid stream into one of said outlets comprises a plurality of control fluid streams under pressure directed against said main stream in said chamber.

7. A fluid diverting valve according to claim 5 in which said means for selectively diverting said main fluid stream into one of said outlets comprises a plurality of valve controlled passages adjacent said main fluid stream for initiating a pressure diflerential in the boundary layer surrounding said main fluid stream.

8. A fluid diverting valve according to claim 5 in which said inlet is connected to an inlet conduit and each of said outlets is connected to an outlet conduit and said means for continuously conveying a portion of said main fluid stream to said source of ambient fluid comprises at least one bypass conduit between said inlet conduit and one of said outlet conduits whereby a portion of said fluid may flow from said inlet conduit into said outlet conduit to be drawn into said chamber.

References Cited UNITED STATES PATENTS 3,181,546 5/1965 Boothe l37-81.5 3,187,763 6/1965 Adams 137-81.5

M. CARY NELSON, Primary Examiner.

W. CLINE, Assistant Examiner.