Particulate Separator

Abstract

A separator for removing particulate contamination from a flowing medium of a different density. The separator incorporates means such as a venturi for directing and accelerating the particulate into a predetermined location in the flow and a screen assembly located downstream of the director. The screen assembly extends across the location in the flow where particles are directed to enable the primary flow path of the medium to bypass the screens if need be. The screen assembly can be comprised of one or more stages which separate and entrap particles. The screen assembly may be spring mounted to accommodate variable velocity flow and may include means for regenerating the screens.

Government Interests

The invention described herein was made in the performance of work under NASA Contract No. NAS 3-14375 and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958 (72 STAT. 435; 42 U.S.C. 2457).

Description

BACKGROUND OF THE INVENTION

Precision components used in fluid transfer systems have failure modes in service directly due to damage received from particles contaminating the fluid in the transfer system. Shutoff valves, check valves and regulators are especially sensitive to this type of damage. When prior art filters are used in such fluid transfer systems the particulate damage can be prevented. However, the potential damage due to high flow restrictions inherent in a plugged filter introduces another potential system failure and therefore the use of conventional filters is restricted to an absolute minimum number in normal service.

SUMMARY OF THE INVENTION

The present particulate separator is suitable to solve the problems mentioned in the above background, so long as the particulate has a density different than that of the flowing medium. The separator operates on a flow of medium by deflecting the particles to a predetermined location in the flow stream and then removing them from the stream by entrapping them between one or more pairs of screens where the upstream screen has a coarser mesh than the downstream screen. Since the screens need not extend completely across the flow path and since either a venturi or reverse venturi can be designed for almost complete pressure recovery, the present separator operates with an inherent low pressure drop. Under changing conditions of particulate contamination concentration, the separator will never plug up. However, the particulate retention capability will change under varying contamination concentration levels. Also, since the screens provide a high degree of particulate retention, the device will operate under varying G load conditions including a zero G condition.

It is therefore an object of the present invention to provide means for separating particulate from a flowing medium wherein the particulate has a density which differs from that of the flowing medium.

Another object is to provide a separator which when used properly is highly effective and economical.

Another object is to provide a separator whose inlet can be quickly and economically changed so that the separator separates either lighter or heavier particles than the medium flowing through the separator.

These and other objects and advantages of the present invention will become apparent after considering the following detailed specification which covers preferred embodiments thereof in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a particulate separator constructed according to the present invention;

FIG. 2 is a cross-sectional view of the separator of FIG. 1 with modified particulate entrapment means;

FIG. 3 is a cross-sectional view of a separator similar to that shown in FIGS. 1 and 2;

FIG. 4 is a cross-sectional view of a separator for separating light particles; and

FIG. 5 is a cross-sectional view of a separator similar to FIG. 4 but having particle entrapment and retention means for capturing heavy particles.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENTS

Referring to the drawings more particularly by reference numbers, number 10 in FIG. 1 refers to a dynamic separator constructed according to the present invention. The separator 10 is especially useful in the flow lines 11 of gas or fluid systems where the separator performs the function of a prefilter to remove quantities of contamination particles upstream of the conventional filters to increase the service life of a conventional filter. The separator 10 includes means which accelerate the medium so that the particulate matter having a different density than the flowing medium, moves to predetermined areas in the flow stream. In the separator 10 of FIG. 1 these means include a venturi 12 which causes heavy particulate to flow in the direction shown by the arrows 14 so they concentrate in the center of the flow stream. Light particles are concentrated in a concentric pattern about the outermost portions of the flow stream. Particle entrapment means 16 are shown placed in the trajectory of the heavy particles to trap them and to prevent them from traveling further with the medium flowing through the separator 10.

The particle retention means 16 as shown includes a conical coarse screen 18 which is connected about its edge 19 to a conical fine screen 20. A space 22 defined between the two screens 18 and 20 forms an entrapment volume for retention of the contamination particles. Since the first screen 18 is of a coarse mesh, particles flow through it due to their momentum and that of the flowing medium. Once through the coarse screen 18, the particles are stopped by the fine mesh screen 20 and are trapped between the two screens in the entrapment zone 22. The particles cannot escape from the entrapment zone 22 because there is no way of introducing the required momentum to the particles in a reverse direction. Even under conditions of reverse flow of the fine mesh of the screen 20 introduces a protective pressure drop which prevents the establishment of a corresponding force which could push the particles back through the coarse screen 18, hence, positive entrapment in the entrapment zone 22 is obtained.

When a large quantity of particles have been captured in the entrapment zone 22, the means 16 can clog and effective filtering no longer takes place. However, the particle entrapment means 16 is supported in the flow by a plurality of spaced arms 24 or other suitable means which provide an essentially unrestricted path for the flow of medium. The primary flow path of the medium whether the particle retention means 16 is saturated with particles or not, is that shown by arrows 26. This means that no matter how clogged the particle entrapment means 16 may become, the flow through the separator 10 is not significantly restricted so that no catastrophic failure such as the clogging of the entire flow line 11 is possible.

The separator 10 as shown in FIG. 1 is especially suitable when a known amount of contaminate is possible and it is desired to make the separator as economical and as simple as possible. Such applications include fuel and a hydraulic fluid filtering in single use spacecraft or in applications where it is easier to replace or clean the separator than to provide regeneration means.

Such regeneration means 28 are shown in FIG. 2 added to the particle entrapment means 16a of the separator 10. The version of the separator 10 shown in FIG. 2 is especially useful in systems which have relatively constant flow velocities. The regeneration means 28 include a vent line 30 connected at the apex 32 of the fine screen 20. The vent 30 is connected to a secondary paticulate disposal area 34. The regeneration function can be accomplished continuously in the secondary disposal area by a continuous bleed off flow or on an intermittent basis. When it is desired to regenerate the separator 10 on an intermittent basis, a shutoff valve 36 can be incorporated into the vent line 30. The arrangement as shown in FIG. 2 has as its primary usefulness prefilter service on coolant inlet lines such as those used to feed ocean water coolant into commercial power and manufacturing installations in which case the particle disposal area can be the ocean.

A further separator configuration is shown by the separator 10' in FIG. 3. The separator 10' is used when it is desired to have efficient operation over a greater range of flow velocities than would be possible with the separator 10 of FIGS. 1 and 2. In the separator 10', the particulate entrapment means 16b is mounted on a spring system such as, for example, the spring arms 38. The spring arms 38 permit the particle entrapment means 16b to move away from the venturi 12 under conditions of high flow and then return to a position closer to the venturi 12 under conditions of low fluid flow. The position of the entrapment is controlled by the force generated by the fluid dynamics on the screens 18 and 20 directly so no secondary force/position control of the means 16 is necessary. The spring arms 38 permit the screens 18 and 20 to operate with a minimum standoff distance from the venturi 12 under low flow conditions when the maximum turning angle (.phi.) of the particles with respect to the flow is required for efficient separation while still allowing efficient operation under high flow velocity conditions by moving to the extended position shown in dashed lines thereby increasing the area of primary flow and preventing the introduction of a high pressure drop in the flowing medium. Since the required particulate turning angle .phi. decreases with increases in particulate velocity, separator 10' permits operation with low pressure drop and high efficiency over a broad range of flow velocities. The separator 10' is especially applicable to applications such as a particulate separator for use in automobile mufflers of the catalytic type which are presently being proposed to enable internal combustion engines to meet air pollution control requirements. The use of the separator 10' to remove the particles can extend the life of the catalytic elements thereby introducing a significant cost savings.

The means 16b of FIG. 3 can also include regeneration means 28' as shown by the retention means 16c of FIG. 4. The regeneration means 28' are similar to those shown in FIG. 2 and include a vent 30' and an optional shutoff valve 36' which can be used when regeneration is desired on an intermittent basis rather than continuously. Regeneration means 28' also include a seal 40 which slides along a portion of the vent 30' to allow the particle retention means 16c to move between the retracted and extended positions in response to flow velocity changes. A frustroconical section 42 is mounted on the end of the vent 30' to prevent the seal 40 from decoupling from the vent 30'. The retention means 16c shown in FIG. 4 when a venturi is used as the particle acceleration means, are useful for all applications where self-cleaning or regeneration is required for service under variable flow velocity conditions. This condition typically occurs in some automotive smog control devices and various nuclear fluid systems.

It should be understood that the screens 18 and 20 will have a mesh size and difference which is dependent upon the particulate matter expected to be entrapped. For example, when it is desired to capture and retain particles in the 35 to 150 micron sizes, screen 20 would have a mesh of openings about 35 microns while the upstream screen 18 would have a mesh of 75 microns. This would provide very fine filtering in such applications as fuel and hydraulic flow particulate problems while much larger screens and series ganged separators of decreasing size can be provided for such applications as ocean water filtering for coolant inlet lines to commercial power and manufacturing installations.

Although in FIGS. 1 through 3 a simple venturi arrangement 12 is shown to accelerate the medium and particles and provide the inertia for the separation operation, other means for concentrating the contamination particles in a portion of the stream and recovering the pressure can be used. For example, in FIG. 4 a body 44 is supported by legs 46 in the center of the stream to form a reverse venturi which causes light particles to concentrate in the center of the stream for collection by means 16c. If heavy particles are present they are concentrated in a concentric pattern adjacent the side wall 48 of the flow tube 11. Particle entrapment means 50 such as those shown in the separator 51 of FIG. 5 can be provided concentrically about the separator 51 near the side wall 48. The means 50 also include a ring shaped coarse screen 52 on the upstream side and a connected ring shaped finer screen 54 on the downstream side to form an entrapment zone 56 therebetween. Since the particle entrapment means 50 are in intimate contact with the side wall 48 of the separator, regeneration means can be provided by simple ring manifold 58 which has openings 60 into the entrapment zone 56. Flow through the manifold can be continuous or controlled by a shutoff valve 62 for intermittent regeneration.

Thus there has been shown and described novel particulate separator means which fulfill all of the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification together with the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.

Claims

What is claimed is:

1. A separator for removing particulate contamination from a medium flowing in a predetermined direction in a conduit, the medium having a different density than the contamination, the separator including:

venturi means to accelerate the flowing medium to flow in a direction different than said predetermined direction so that the contamination is concentrated in a predetermined downstream area of the flow and to recover the pressure drop caused by the acceleration; and

means positioned in said predetermined downstream area of the flow to entrap and retain said particulate contamination, said last named means including a first screen, a second screen of finer mesh than said first screen and downstream therefrom and support means connected to said screens to support said first and second screens in said predetermined downstream area of the flow and spaced from the conduit whereby a primary flow path around said first and second screens is present, said first and second screens being connected together at at least one edge thereof and defining an entrapment zone therebetween in which the particulate is entrapped.

2. The separator defined in claim 1 wherein said first and second screens are conical in shape and connected at the circular edges thereof with said second screen having an enclosed conical angle which is less than the conical angle of the first so that said entrapment zone is defined therebetween, the apex of said first screen and the apex of said second screen being downstream from the connected edges thereof.

3. The separator defined in claim 2 including regeneration means, said regeneration means including a vent conduit extending from through the apex of said second screen to outside the flow conduit, said vent conduit being connected to said second screen.

4. The separator defined in claim 1 wherein said first and second screens are connected to and extend inwardly from the flow conduit and upstream, the connection of said first and second screens being upstream from their connections to the flow conduit.

5. The separator defined in claim 4 wherein the entrapment zone defined by said first and second screens extend to the flow conduit, the separator including means outside the flow conduit in flow communication with the entrapment zone to provide regeneration means for the screens.

6. The separator defined in claim 1 wherein said venturi means to accelerate the flowing medium include a reverse venturi.

7. The separator defined in claim 6 wherein said first and second screens are conical in shape and connected at the circular edges thereof with said second screen having an enclosed conical angle which is less than the conical angle of the first so that said entrapment zone is defined therebetween, the apex of said first screen and the apex of said second screen being downstream from the connected edges thereof.

8. The separator defined in claim 7 including regeneration means, said regeneration means including a vent conduit extending from through the apex of said second screen to outside the flow conduit, said vent conduit being connected to said second screen.

9. The separator defined in claim 6 wherein said first and second screens are connected to and extend inwardly from the flow conduit and upstream, the connection of said first and second screens being upstream from their connections to the flow conduit.

10. The separator defined in claim 9 wherein the entrapment zone defined by said first and second screens extend to the flow conduit, the separator including means outside the flow conduit in flow communication with the entrapment zone to provide regeneration means for the screens.

11. A separator for removing particulate contamination from a medium flowing in a predetermined direction in a conduit, the medium having a different density than the contamination, the separator including:

venturi means to accelerate the flowing medium to flow in a direction different than said predetermined direction so that the contamination is concentrated in a predetermined downstream area of the flow;

means positioned in said predetermined downstream area of the flow to entrap and retain said particulate contamination, said last named means including a first screen and a second screen of finer mesh than said first screen and downstream therefrom, said first and second screens being conical in shape and being connected at the circular edges thereof with said second screen having an enclosed conical angle which is less than the conical angle of the first so that an entrapment zone is defined therebetween in which the particulate is entrapped, the apex of said first screen and the apex of said second screen being normally downstream from the connected edges thereof; and

spring arms which support said first and second screens spaced from the conduit so that said screens are moved downstream in response to increased flow velocity of the medium and are returned upstream in response to decreased flow velocity of the medium.

12. The separator defined in claim 11 including regeneration means connected to the entrapment zone, said regeneration means including:

a vent conduit extending from through the apex of said second screen to outside the flow conduit; and

seal means connecting said vent conduit to said second screen and allowing relative upstream and downstream movement therebetween.

13. The separator defined in claim 12 including regeneration means connected to the entrapment zone, said regeneration means including:

a vent conduit extending from through the apex of said second screen to outside the flow conduit; and

seal means connecting said vent conduit to said second screen and allowing relative upstream and downstream movement therebetween.

14. The separator defined in claim 11 wherein said venturi means include a reverse venturi.