CA1041914A

CA1041914A - Fluid treating apparatus

Info

Publication number: CA1041914A
Application number: CA216,139A
Authority: CA
Inventors: William J. Sayer
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-12-17
Filing date: 1974-12-16
Publication date: 1978-11-07
Also published as: FR2254359B1; JPS5094569A; FR2254359A1; DE2459356A1

Abstract

APPLICATION FOR UNITED STATES PATENT

FLUID TREATING APPARATUS

ABSTRACT OF THE DISCLOSURE
Fluid treating apparatus particularly for treating gases such as air including a multi-element filter assembly having a means for moving the fluid through the assembly located between elements of the assembly.

Description

BACKGROUND OF THE INVENT ION

The invention relates generally to fluid treatment and more specifically to apparatus for filtering gases such as air.
The prior art discloses a wide variety of air filtering systems employing various combinations of known filtering clemcnts. For example, U.S. Patent No. 3,438,180 to ~. F.
glouda, discloses air cleaning apparatus in which air passes through a wire mesh screen, an electrostatic filter and a charcoal pack. In U.S. Patent No. 3,172,747 to K. ~. Nodolf, the air is drawn by a fan through a pre-filter, an electrostatic filter, and a charcoal filter. U.S. Patent No. 3,672,126 to W. H. Goettle discloses a pump which draws air through a porous pre-filter, an electrostatic filter, a charcoal filter and a porous filter similar to the pre-filter. U.S. Patent No.

2,945,554 to E. M. Berly discloses the use of a "baa filter"
(Figs. 4 and 8) in an air cleaning device.

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SUMMARY OF THE I~VENTION

In accordance with the teachings of the present invention, it h~s been discovered that the proper selection and order of known filter elements results in a fluid treating apparatus having a longer life of the individual filter elements and having a longer life of the fluid pump or fan. For example, in the case of a charcoal filter element the inventive co~bina-tion results in preventing contaminating particles from - reaching the charcoal surfaces thereby allowing these surfaces to absorb gases thereby increasing efficiency. With regard to the fan or pump, longer life results from a reduction of air-borne particles encountered by the device. Further, a utilization of the pump in a pull/push arrangement amid the filter elements results in higher efficiency than as if the pump were located upstream or downstream of all the filter elements. Down time for cleaning or replacing filter elements is minimized by the teaching of the invention. The resulting apparatus provides a highly efficient filter assembly which operates at a lower cost than prior art filter apparatus.
Broadly stated, the present invention is a fluid treating apparatus in a fluid duct through which the fluid to be treated flows in a predetermined direction comprising: first filter means disposed in the duct to filter substantially all of the fluid passing through the duct, the first filter means including at least one high efficiency filter, fluid moving means located downstream of the first filter means for moving fluid through the duct, second filter means disposed in the duct downstream of the fluid moving means, the second filter means including a - ~ - 2 -~.
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These and other advantages of the present invention will be better understood as the present disclosure is read and understood.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of a generalized fluid treating apparatus according to the present invention.
Figure 2 is a schematic diagram of a preferred embodiment of the fluid treating apparatus according to the present invention.

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~ 14 1 ¦ DE:SCRIPTION OF T~ rRl~FERRED E~IRODIMENI'S
2 ¦ ReferrincJ now to Figurc 1 of the drawings whcrein

3 ¦ a generalized schematic diagram of the fluid treating apparatus

4 ¦ according to the prcsent invention is shown. A fluid flow duct 2

- 5¦ has input filter means 4 located in the duct 2 so as to filter 61 substantially all of the fluid pa3sing therethrough. While the 7¦ present invention is not restricted to the processing of gases ~¦ or air, the exemplary embodiments, for convenience, will be 9¦ described in the context of air treatment. Means 6 for moving 10¦ air through the duct 2 in the direction of the arrows is located 11 ¦ in duct 2 between the input filter means 4 and output filter 12¦ means 8. ~eans 6 can be a suitable air pump or fan selected in 13¦ view of the air volume requircnents of the system. The output 1~ ¦ filter means 8 is located in the duct 2 so as to filter 15 ¦ substantially all of the fluid passing therethrough.
16¦ The location of the air moving means 6 between the 171 input and final filter means (~ and 8) contributes to the 18 efficiency of the system and protects the pump or fan from dirt 19 thereby extending the pump or fan life.

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~¦ Figurc 2 5hows one ~refcrred en~bodimcnt of the 21 invention whereiIl the input filter means 4 includes an electro-31 static filter lO and a bag filter 12. Filter lO can be a sin~Jle - 41 cell unit or preferably double cell. The location of filter lO
5¦ first in the assembly permits its removal for washing, which 61 is frequently required by electrostatic filters. The bag filter 71 12 incrcases the efficiency of filtration and provides a bac~-up 81 to electrostatic filter lO to permit continued operation of the 9¦ system when the filter lO is rcmoved for cleaning, thus protectin 10¦ .the fan or pump 6 fro~ dirt buildup and preventing particles from 11¦ reaching the final filter means 8. The bag filter 12 is also 12¦ useful in keeping partic_es out of the system when the electro-13 ¦ static filter 10 is not operating due to a lack of electric power.
~ 14 I Typical co~mercial electrostatic filters remove 70 to 1 15 1 80% of airborne particles. Such filters are well known in the 16 ¦ art and can be purchased. ~igh efficiency electrostatic filters 17 ¦ are available which provide greater than 80% efficiency.
18¦ An electrostatic filter is preferred in the input 19¦ filter means 4 due to its ease of cleaning and reUsability.
20¦ However, if desired, the input filter means 4 can comp~ise other 21 ¦ types of high efficiency filters either singly or in pairs.
22¦ For example, in a low cost system one or two bag filters can be 23 used. The National ~ureau of Standards defines hi~h efficiency 24 filter as one having greater than 804 efficiency.
~he final filter means 8 preferably comprises a solid 26 matrix niedium filter followed by a high efficiency filter, such as 27 an ac~ivatcd charcoal filter 14 followed by a high efficiency 28 particulate (lIEP~) filter 16. Alternately, the charcoal filter 29 may be replaced or augmented by a suitable diatomaceous clay filter or any other type of solid matrix filtering mcdium includ 31 ing a ~IEPA filter. Solid matrix filtering media include cardboard 32 paper, charcoal, clay, fiber glass, wool and other such materials.

" '' ' ' I ¦ The location of charcoal filter 14 downstream from the input 2 ¦ ~ilter means 4 prolongs the life of the charcoal filter by 3 ¦ prevcnting particles from reaching the filter which tend to cover 4 ¦ the surface of a charcoal filter and leave it ineffective. The 5 ¦ location of thc pump or fan 6 before the charcoal filter 14

6 ¦ prevents charcoal particles from reaching the pump or fan 6.

7 ¦ The charcoal filter 14 functions to remove odors from the air

8 ¦ supply and to remove sub-micron particles und~r about 0.3 micron.

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1l ¦ The ~lEPA filter 16 acts as a final clean-up of any 12 ¦ air coming through the system and further acts to catch any I3 pieces of charcoal that might be dislodged from the charcoal I4 filter 14 if a charcoal filter is used or to catch any particles from the pump or fan 6. Filter 16 is preferably a high efficiency 16 particulate filter having 85% or greater efficiency, although 17 lesser efficiency can be tolerated if degraded system performance l8 i9 acceptable. One type of ilEPA filter, manufactured by 19 Continental Air Filters has an efficiency of 99& for 0.3 micron or larger particles.
21 The system as shown in Figure 2 has been tested in 22 Palo Alto, California. A typical outside air particle count at 23 that location is 50,000 to 300,000 particles/ft3. Applying such 24 outside air to the inlet of the duct of the Figure 2 system, the ~artlcle count at the outlet is less than 100 particles/ft3 and 26 typically close to zero/ft . For outside particles greater 27 than 5 microns ~a typical count of 400 - 3000/ft3) the outlet 28 count is substantially zero. For outside particles greater than 29 10 microns ta typical count of 0 - 1000/ft3) the outlet count is substantially zero.

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~ 14 I ¦ The present invention is usable in nearly any 2¦ environment in which clean air is required. One such application 3¦ is in an air conditioninq systcm for a home, office, hospital, 4¦ vehicle, aircraft or vessel (particularly a submarine where 51 clean air for humidification and ioni~ation is extremely important). I'he invention is also applicable in industrial 71 processcs, particularly for "clean rooms~ in semiconductor manu-81 facture, drug manufacture, food processing (to extend shelf life 9 I of products), computer opcrations and the like. The invention 10 ¦ is also of use in providing clean air for combustion processes .

11 I including engines, both upstream ar.d/or downstream of such

12 ¦ processes.

13 ¦ It will be apparent that the present lnvention i~

14 ¦ useful in virtually any application where clean air is required.

15 ¦ Modifications of thc present invention will be 1~ ¦ apparent to those of ordinary skill in the art. The invention is 2Z theref=re to b li~lted only by the =ope oi the spponded =laims.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Fluid treating apparatus in a fluid duct through which the fluid to be treated flows in a pre-determined direction comprising: first filter means disposed in said duct to filter substantially all of the fluid passing through said duct, said first filter means including at least one high efficiency filter, fluid moving means located downstream of said first filter means for moving fluid through said duct, second filter means disposed in said duct downstream of said fluid moving means, said second filter means including a solid matrix filter, and a high efficiency filter downstream of said second filter means to act as a final filter for fluid flowing through said duct.

2. The apparatus of Claim 1 wherein said first filter means further comprises two high efficiency filters.

3. The apparatus of Claim 2 wherein the upstream high efficiency filter in said first filter means is an electrostatic filter.

4. The apparatus of Claim 1 wherein said solid matrix medium filter is a charcoal filter.

5. The apparatus of Claim 2 wherein said two high efficiency filters in said first filter means comprise first and second bag filters.