WO1991010832A1

WO1991010832A1 - Silencer system for hydrokinetic amplifier

Info

Publication number: WO1991010832A1
Application number: PCT/US1991/000276
Authority: WO
Inventors: Carl D. Nicodemus
Original assignee: Helios Research Corp.
Priority date: 1990-01-17
Filing date: 1991-01-14
Publication date: 1991-07-25
Also published as: AU7239491A

Abstract

A system for reducing the noise associated with the operation of a hydrokinetic amplifier (10) in which a pressurized gas is introduced into the amplifier in the region of its diffuser (16). In the preferred system, the pressurized gas is introduced into the amplifier at a distance below the minimum cross-sectional area 20 of its mixing chamber 12 no greater than approximately seven times the diameter of the minimum cross-sectional area. The gas is preferably pressurized in the hydrokinetic amplifier itself and delivered to an accumulator or reservoir (21). A control valve (26) permits the pressurized gas to flow into the region of the diffuser only when the hydrokinetic amplifier is operating. In the preferred system, the valve is responsive to the pressure of the liquid output of the hydrokinetic amplifier.

Description

SILENCER SYSTEM FOR HYDROKINETIC AMPLIFIER

TECHNICAL FIELD

This invention relates to hydrokinetic amplifiers. Such devices (see U.S. Patent No. 4,569,635 and other patents referred to below) are used for pressure amplification. While hydrokinetic amplifiers have some similarity to steam injectors, the former include critical structural differences and achieve significantly greater pressure amplification.

BACKGROUND

A hydrokinetic amplifier, as explained more fully in U.S. Patent No. 4,569,635, forms a free liquid jet clear of internal walls and surrounds the liquid jet within a mixing chamber with a high velocity vapor that can condense or dissolve into the liquid. The vapor efficiently accelerates the liquid and transfers a large portion of its substantial momentum to accelerate the liquid jet through a minimum cross-sectional area which defines an exit for the mixing chamber. In the acceleration process, the vapor merges with the accelerated liquid whose increased kinetic energy is then converted to pressure in a diffuser.

Further, as explained more fully in U.S. Patent No. 4,673,335, gases can be admitted to the mixing chamber of a hydrokinetic amplifier at surprisingly large flow rates to merge with the liquid and vapor and become compressed in the pressurized liquid output, making the hydrokinetic amplifier an effective gas compressor. In some applications, this combined output mixture of compressed gas and liquid is collected in a pressurized reservoir where the gas serves as a compressible medium and the pressurized liquid is used for cleaning purposes. In U.S. Patent No. 4,781,537, a hydrokinetic amplifier is disclosed in which an input port for the introduction of secondary fluid is positioned so that the secondary fluid merges with the primary liquid jet at a point beyond the the amplifier's minimum cross-sectional area, but before the primary jet reaches the diffuser; and both the secondary fluid and the primary liquid jet combine and proceed into the diffuser. As described in the latter patent, this further input port makes it possible to add material to the primary pressurized liquid flow generated by the amplifier. The secondary flow of the additional material varies inversely with the fluid flow resistance to the amplifier's output flow, while the amplifier's primary inflows of operating liquid and vapor remain unchanged.

During the operation of hydrokinetic amplifiers, such as those being used in the manner just described above for compressing gases and for controlling the flow rate of a secondary liquid, the vapor (e.g., steam) condenses into the liquid (e.g., water) so rapidly that the steam increases to supersonic velocities and imparts this momentum to the liquid stream which is, in turn, accelerated to very high velocities (e.g., approximately 300 feet per second). This high velocity is converted to high pressure in the diffuser portion of the amplifier. This just-described operation of the hydrokinetic amplifier generates considerable noise, and this noise is often considered to be unacceptably loud. In some instances, persons operating cleaning equipment powered by hydrokinetic amplifiers have characterized the noise as frightening.

SUMMARY OF THE INVENTION

I have discovered that if pressurized gas is introduced into the region of the diffuser when the hydrokinetic amplifier is operating, its noise is remarkably reduced without any commercially significant effect on the efficiency of its operation. Since gases can be compressed in an operating hydrokinetic amplifier, I have also discovered that it is possible to use the amplifier itself to generate the pressurized gas which can be used to quiet its operation. The compressed gas is gathered in an accumulator or reservoir and is introduced into the region of the diffuser when the amplifier is operating.

According to the invention, pressurized gas is only delivered to the diffuser after the hydrokinetic amplifier has achieved sufficient primary liquid/vapor velocities to sustain its operation. That is, attempts to introduce the silencing gas prior to attainment of these operating velocities can interfere with the normal function of the hydrokinetic amplifier and prevent its proper operation. Therefore, introduction of the pressurized gas into the region of the amplifier's diffuser is preferably controlled by a valve which is only opened to allow delivery of the pressurized gas when the amplifier's primary liquid output has attained a predetermined pressure indicative of sustained operation.

In the preferred embodiments, the control valve is responsive to a pressure sensor positioned in the conduit which delivers the pressurized output of the hydrokinetic amplifier to an appropriate reservoir. The sensor may be selected from any one of a variety of forms. For instance, if designed to produce an electronic signal whenever the amplifier's output reaches a predetermined pressure, then the control valve can be solenoid-operated. On the other hand, the control valve may be a hydraulically operated pilot valve responsive to a rise in liquid pressure in the output conduit, the sensor being in the form of a small tube interconnecting the conduit and the pilot valve.

However, in certain installations where the hydrokinetic amplifier is set up for continuous operation, e.g., when it is used to deliver pressurized liquid to a spray bar for cleaning the web of papermaking machinery, it is possible to omit use of the pressure sensor; and the control valve is manually opened after the spray bar system has been adjusted for optimum operation. Further, in some noncontinuous installations, it may also be possible to omit use of the pressure sensor and still control the introduction of the silencing pressurized gas with a control valve that is automatically operated. Such installations may use a solenoid-operated control valve in combination with a timing circuit which delays operation of the control valve for a timed interval sufficient to allow the hydrokinetic amplifier to start up and attain its operation-sustaining velocities and output pressure.

DRAWINGS

Figure 1 is a partially schematic, cross-sectional view of a portion of a hydrokinetic amplifier of the type contemplated for use with the noise-reducing system shown in block form in Fig. 2.

Figure 2 is a schematic block diagram of a preferred arrangement of apparatus comprising a noise- reducing system according to the invention incorporated with a known tank system used for supplying pressurized liquid for industrial cleaning purposes.

DETAILED DESCRIPTION

As shown in the drawings, a primary liquid input enters hydrokinetic amplifier 10 through a liquid input nozzle 11 to form a primary liquid jet directed into a mixing chamber 12, which is partially cut away in Fig. 1 to shorten the view. Vapor surrounds and accelerates the primary liquid jet after entering hydrokinetic amplifier 10 via vapor nozzle 13. The vapor merges with the primary liquid jet and accelerates it through nozzle 15 and the minimal cross- sectional area 20 which form the exit of mixing chamber 12. Minimal cross-sectional area 20 can be reduced axially to a single line within nozzle 15, or it can extend axially for a distance (as illustrated in Fig. 1) , terminating at end 14 to discharge and direct the accelerated primary liquid jet toward a diffuser 16 and the latter's pressure-increasing diverging region 17. As indicated above (and as fully explained in U.S. Patent No. 4,569,635), hydrokinetic amplifier 10 combines the primary liquid and vapor to produce an extremely-high velocity liquid jet which is converted in diffuser 16 to a pressure-amplified liquid output.

As indicated in Fig. 2, the pressurized output of amplifier 10 is delivered to and accumulated in a reservoir in the form of pressurized tank 21 from which it is delivered on demand to liquid output apparatus 22 (e.g., a spray bar or a plurality of gun-type nozzles used for industrial cleaning) .

Hydrokinetic amplifier 10 also has another port 23 which opens into its mixing chamber 12. (Although port 23 has been omitted from Fig. 1, it is schematically indicated in Fig. 2 and is explained fully in above-mentioned U. S. Patent No. 4,673,335 which is incorporated herein by reference.) Once normal operating conditions are achieved within mixing chamber 12, port 23 is used to admit a compressible gas (e.g., air) into mixing chamber 12. The normal operating action of hydrokinetic amplifier 10 pressurizes the gas which passes through the inlet and outlet orifices of diffuser 16 along with the pressurized liquid, being accumulated in tank 21.

Pressurized gas 24 accumulates in the top of tank 21 and flows through conduit 25 to a control valve 26. Typically, normal operating pressures present in tank 21 range from 200 psi to 500 psi. When open, valve 26 allows pressurized gas 24 to flow through conduits 25 and 27 and into hydrokinetic amplifier 10 through port 19.

Control valve 26 is moved to its "open" position only when a pressure sensor 28 indicates that the liquid output from said hydrokinetic amplifier exceeds a predetermined liquid pressure. Otherwise, as indicated above, the premature introduction of pressurized gas 24 may disrupt, or at least may adversely affect, the operation of amplifier 10. However, as soon as the pressure present in output passageway 29 reaches a level (based upon pragmatic testing of the system) at which amplifier 10 can be expected to sustain continuous operation, the noise-reducing pressurized gas 24 is permitted to flow into port 19 and diffuser 16.

When hydrokinetic amplifier 10 ceases operation, the pressure present in output passageway 29 is reduced significantly; and control valve 26 is closed immediately, readying amplifier 10 for restart and simultaneously preventing loss of pressurized gas 24 from reservoir 21. At the same time, a check valve 30 prevents backflow of the pressurized operating fluid from reservoir 21.

Fig. 1 illustrates a preferred location for port 19, namely, so that pressurized gas 24 surrounds the accelerated liquid jet in passageway 18 at a position immediately below minimum cross-sectional area 20. The pressure at this point within hydrokinetic amplifier 10 is sometimes below atmospheric. It is believed that the pressurized gas, when entering at this preferred position, is accelerated to supersonic speeds by the difference between the very low pressure in this area of the amplifier and the relatively high pressures at the top of reservoir 21, and that the entering gas adds its velocity to that of the primary liquid jet prior to the latter's entrance into diffuser 16. Therefore, although the pressurized gas passes almost immediately into the upper portion of diffuser 16, its entry at this preferred location further enhances pressure amplification of the primary liquid output in addition to reducing the amplifier's noise of operation.

However, passageway 18 is not the only position where pressurized gas can be introduced into hydrokinetic amplifier 10 for noise-reduction purposes. Fig. 2 indicates another possible location, namely, inlet 31 (shown schematically in dotted lines) at which it has been found that the introduction of pressurized gas provides good noise reduction. Inlet 31 is positioned at a distance below minimum cross-sectional area 20 equivalent to approximately seven times the diameter of minimum cross-sectional area 20.

In any event, it is believed that good noise reduction can be achieved by designing the gas inlet so that the pressurized gas will enter and generally surround the primary liquid jet below the minimum cross-sectional area of the mixing chamber but at no greater a distance therefrom than that indicated by location 31 as just defined above. While these just-described locations for the inlet are preferred, it is possible to introduce pressurized gas into diffuser 16 at points below inlet 31 and still achieve noticeable noise reduction. For instance, in installations where the hydrokinetic amplifier is being operated so that its liquid output is below its rated capacity, significant noise reduction is still achieved when the pressurized gas is introduced proportionally lower (i.e., towards the exit) in the diffuser.

As suggested above, pressure sensor 28 can be selected from any number of possible devices, including those producing an output in the form of an electrical potential or a hydraulic pressure, or it can even be nothing more than a small tube running between conduit 29 and a pilot valve which opens or closes the passageways 25 and 27 between reservoir 21 and port 19 in response to the pressure present in the tube. Of course, control valve 26 is designed to be compatible with, and responsive to the signal generated by, pressure sensor 28, being a solenoid if the signal is an electric potential, etc.

Further, it is possible to reduce noise without using the preferred automatic system just described above. All that is necessary is that pressurized gas be introduced into the hydrokinetic amplifier after the amplifier attains an operation-sustaining output pressure, and that the pressurized gas be joined with the amplifier's liquid/vapor stream in the region of the diffuser, namely, at a location either (a) within the diffuser or (b) above the diffuser but below the amplifier's minimum cross-sectional area. As already noted above, this can be done by manually opening a valve to introduce the pressurized gas, or it can be done automatically using a time-delay circuit to operate a solenoid-controlled valve. Also, the gas does not have to be pressurized in the economical manner provided by the preferred system disclosed above. An appropriately pressurized gas, from whatever source, will suffice to reduce the amplifier's undesirably frightening noise.

Claims

I CLAIM:

1. A system for reducing noise associated with the operation of a hydrokinetic amplifier having (a) a mixing chamber with an exit defining a minimum cross-sectional area and (b) a diffuser positioned below and spaced from said minimum cross-sectional area, said amplifier combining a liquid jet and vapor in said mixing chamber and accelerating the liquid jet through the minimum cross-sectional area to produce a pressure-amplified liquid output, said system comprising:

- a source of pressurized gas; and

- a conduit for introducing said pressurized gas into said amplifier in the region of the diffuser when said amplifier is operating.

2. A system according to claim 1 further comprising a valve for controlling the flow of said pressurized gas through said conduit, said valve permitting pressurized gas to flow through said conduit only when said liquid output reaches a predetermined amplified pressure.

3. A system according to claim 2 wherein said valve is manually operated.

4. A system according to claim 2 further comprising a device for sensing the amplified pressure of said liquid output, and wherein said valve is responsive to said pressure-sensing device.

5. A system according to claim 1 wherein said conduit delivers said pressurized gas to the amplifier at a position immediately below the minimum cross-sectional area of said mixing chamber.

6. A system according to claim 1 wherein said conduit delivers said pressurized gas to the diffuser at a distance below the minimum cross-sectional area of said mixing chamber equivalent to approximately seven times the diameter of said minimum cross-sectional area.

7. A system according to claim 1 wherein said conduit delivers said pressurized gas to the amplifier at a distance below the minimum cross-sectional area of said mixing chamber no greater than approximately seven times the diameter of the minimum cross-sectional area.

8. A system according to claim 1 wherein said source of pressurized gas is said hydrokinetic amplifier which further comprises a fluid-input orifice in said mixing chamber, said gas initially entering said mixing chamber through said fluid-input orifice to be pressurized along with the liquid output of said hydrokinetic amplifier.

9. A system according to claim 8 wherein said source of pressurized gas further comprises an accumulator for storing gas pressurized by said hydrokinetic amplifier.

10. A system according to claim 9 wherein said accumulator further comprises a reservoir in which the pressurized liquid output of said hydrokinetic amplifier is collected.

11. A method for reducing noise associated with the operation of a hydrokinetic amplifier which combines a liquid jet and vapor in a mixing chamber and accelerates the liquid jet through a minimum cross-sectional area to a diffuser positioned below and spaced from said minimum cross-sectional area, said amplifier producing a pressure-amplified liquid output, said method comprising the steps of: pressurizing a gas; and introducing said pressurized gas into said amplifier in the region of the diffuser when said amplifier is operating.

12. The method of claim 11 wherein said pressurized gas is introduced into said amplifier at a position immediately below the minimum cross-sectional area of said mixing chamber.

13. The method of claim 11 wherein said pressurized gas is introduced into said amplifier a distance below the minimum cross-sectional area of said mixing chamber no greater than approximately seven times the diameter of said minimum cross-sectional area.

14. The method of claim 11 comprising the further steps of: sensing the pressure of the liquid output of said hydrokinetic amplifier; and introducing said pressurized gas into said amplifier only when said liquid output pressure exceeds a predetermined value.

15. The method of claim 14 wherein said introducing step further comprises using a gas delivery arrangement which includes a valve responsive to said liquid output pressure.

16. The method of claim 11 wherein said pressurizing step further comprises admitting said gas into the mixing chamber of the hydrokinetic amplifier to be pressurized along with the liquid output.

17. The method of claim 16 comprising the further step of accumulating said pressurized gas in a reservoir prior to said introducing step.

18. Silencing apparatus for a hydrokinetic amplifier which combines a liquid jet and vapor in a mixing chamber and delivers the jet through a minimum cross-sectional area to a diffuser spaced from said area to produce a pressure-amplified liquid output, comprising:

- an opening in said mixing chamber to admit a gas to be pressurized along with said liquid; a reservoir downstream of said hydrokinetic amplifier for collecting said pressurized liquid and gas; and a passageway interconnecting said reservoir and said hydrokinetic amplifier for introducing pressurized gas from said reservoir into the region of said diffuser.

19. Apparatus according to claim 18 wherein said passageway includes a valve responsive to the pressure of said liquid output.

20. Apparatus according to claim 19 wherein said apparatus further comprises a conduit for delivering said liquid output to the reservoir and said valve is responsive to pressure in said conduit.