WO1996021623A1

WO1996021623A1 - Decontamination reactor system and method of using same

Info

Publication number: WO1996021623A1
Application number: PCT/US1995/000316
Authority: WO
Inventors: William S. Coury
Original assignee: Coury William S
Priority date: 1995-01-10
Filing date: 1995-01-10
Publication date: 1996-07-18
Also published as: AU1677595A

Abstract

The present invention provides a reactor system for decontaminating a supply of contamined liquid, comprising a pressurizable reaction vessel (200) having an inlet for introducing a fluid, an outlet for expelling a fluid while retaining a pressure within said reaction vessel (200), a catalyst (106), and a granule support plate (108) for retaining said catalyst (106) within said reaction vessel (200), a pump (110) in fluid connection with the inlet for introducing a fluid into said reaction vessel (200), and a supply of gas (112) in fluid communication with said pump (110), whereby said pump (110) is operated so that the supplied gas and the contaminated liquid are intermixed and supplied under pressure to said inlet for introducing a fluid into the reaction vessel (200) and whereby the pressurized gas and liquid mixture is maintained at a sufficient pressure within said reaction vessel (200) to prevent the formation of bubbles of the gas within said reaction vessel (200).

Description

DECONTAMINATION REACTOR SYSTEM AND METHOD OF USING SAME

Background of the Invention

Field of the Invention:

The invention relates to a waste water decontamination reactor system and method of using same. In particular, the invention relates to a rector system for and method of maintaining a two-phase (liquid/solid) operating environment within an ozone supersaturated decontamination reactor, thereby maximizing the contact of contaminants with ozone and oxygen particles, while minimizing loss of catalytic material due to turbulence associated with expansion of free ozone and/or oxygen.

Background Art:

The prior art in the field of ozone-based decontamination is crowded. For instance, United States Patent No. 4,696,739 (hereinafter "the 739 patent") discloses a water purification apparatus having multiple countercurrent ozone extraction columns. The apparatus, however, involves a three-way (gas/liquid/solid) reaction vessel. See Col. 2, lines 56-64. The apparatus is designed to bubble the ozone through the liquid. Col. 1, line 51. Therefore, there exists a need for a reaction vessel which does rely upon a three-phase reaction.

The device disclosed in United States Patent No. 3,336,099 (hereinafter "the

'099 patent") is an apparatus for sanitizing liquids. The '099 patent apparatus includes baffles, to enhance the gas liquid contact. However, the '099 patent apparatus, like the 739 patent apparatus, permits the ozone/air to bubble in the reactor.

United States Patent No. 5, 114,576 discloses a first ozonation of waste water followed by a catalytic decomposition of the remaining ozone before discharge of the cleansed fluid. United States Patent No. 5,116,574 (hereinafter "the '574 patent") discloses multiple extraction systems with recycled exhaust gas to increase overall oz usage efficiency. The '574 patent also discloses the use of discrete modules to effect a fixed percent improvement for each module.

United States Patent No. 4,007,118 (hereinafter "the '118 patent") discloses a apparatus for ozone oxidation of waste water using catalytic media reactors where the granules are contained in a filter bag. The '118 patent also discloses the use of an upflow, dispersed catalyst bed where the granules are dispersed with ozone-containing gas, while the fines are collected downstream of the dispersed bed and recycled back t the bed. The '118 patent further discloses operating the catalytic reactors at pressures above atmospheric.

United States Patent No. 5,173,257 discloses the simultaneous use of gaseous ozone and dissolved ozone to sanitize solid particles and react with dissolved contaminants. United States Patent No. 5,190,659 discloses the use of a complex filter valve apparatus to automate the necessary steps of cleaning, backwashing and reusing an ozone-reactive filter. United States Patent No. 4,898,679 (hereinafter "the '679 patent") discloses the use of near freezing temperatures to increase the concentration ofozone in water. In the '679 patent, the supercharged water is then heated at the point of use and used to disinfect or decontaminate sludge, other contaminated fluids or equipment.

In all of the prior art, the simple task of ozonating water and later catalytically decomposing the ozone to continue the decontamination was complicated by the demands of handling a 3-phase system (gas/liquid/solid). Therefore, there exists a nee for an apparatus and method capable of performing decontamination in two phases wh maximizing ozone concentration. SUMMARY OF THE INVENTION

It is an object of the present invention to simplify the ozonation/deozonation process by eliminating the excess equipment currently required to handle catalyst fines. It is a further object of the present invention to eliminate automation as practiced in the prior art. It is a further object to eliminate reactive and non-reactive filtration systems and their associated maintenance. Another object of the present invention is to eliminate 3-phase systems (gas liquid/solids) from the ozonation/catalytic deozonation process. A further object is to provide a substantially gas-free ozonation reactor. It is a further object of the present invention to increase the oxidative power of ozonated water by supersaturating the water with ozone and oxygen under pressure before catalytic decomposition.

It is another object of the present invention to provide a method of decontaminating a supply of contaminated liquid, comprising the steps of directing a supply of gas and the supply of contaminated liquid to a pump in fluid communication with a pressurizable reaction vessel having a means for introducing a fluid, a means for expelling a fluid while retaining a pressure within the vessel, a catalyst, and a means for retaining the catalyst whhin the vessel, wherein the pump is in fluid connection with said means for introducing a fluid into said reaction vessel, operating said pump so that said supplied gas and the contaminated liquid are intermixed and forced under pressure through said means for introducing a fluid into the reaction vessel at a sufficient pressure such that whhin said reaction vessel the pressure prevents the formation of bubbles of the gas, and operating said reactor system for a period of time sufficient to decontaminate the liquid to a preselected level of decontamination.

To accomplish these objects, the present invention provides a reactor system for decontaminating a supply of contaminated liquid, comprising a pressurizable reaction vessel having a means for introducing a fluid, a means for expelling a fluid while retaining a pressure within the vessel, a catalyst, and a means for retaining the catalyst within the vessel, a pump in fluid connection with said means for introducing a fluid into said reaction vessel, and a supply of gas in fluid communication with said pump, whereby said pump is operated so that the supplied gas and the contaminated liquid ar intermixed and supplied under pressure to said means for introducing a fluid into the reaction vessel and whereby the pressurized gas and liquid mixture is maintained at a sufficient pressure within said reaction vessel to prevent the formation of bubbles of t gas within said reaction vessel.

Additional advantages of the invention will be set forth in part in the descriptio which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attaine by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restricti of the invention, as claimed.

The accompanying drawings, which are incorporated in and constitute a part o this specification, illustrate several embodiments of the mvention and together with the description, serve to explain the principles of the invention.

Brief Description of the Drawings

Figure 1 shows a schematic view of the reactor system of the present invention

Detailed Description of the Preferred Embodiments

The present invention may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and to the Figure.

Before the present devices and methods are disclosed and described, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

Throughout this application, various publications are referenced. The disclosures of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

The invention is preferably a plurality of modular gas extraction tanks in series.

Each modular gas extraction tank or vessel is connected, under pressure, to an upflo catalyst bed with an underflow feedback line connected to the bottom of each extraction tank. The upstream-most extraction tank overflows continuously back to a feed tank.

Each pressurized catalytic tank discharges to the next extraction tank through a static back-pressure device such as, but not limited to, an orifice or a partially open manually-operated valve. One skilled in the art would recognize that this system is simpler than prior art systems because it has no moving parts (except for the module pump), it has no automatic control devices, and all flows are controlled by both the pump pressure and gravity.

The fluid in the extraction tanks is a gas/liquid mixture having a broad distribution of bubble sizes. The smallest bubbles, whose size will vary depending upon user-defined reactor parameters, containing undissolved ozone and oxygen, are entrained by the downflow liquid velocity and enter the pump suction together. Larger bubbles rise to the top of the extraction tank and eventually exhaust to the atmosphere. Exhaustion is accomplished by any one of several well known techniques.

The small bubble/liquid mixture is pressurized and mixed in the pump. After mixing and pressurization, the bubbles dissolve into the liquid according to Henry's law. This process is well known and is called supersaturation by those of ordinary skill in the art. A number of well developed techniques for supersaturation have been developed the beer and soft drink industries. Any one of these techniques would be suitable for present invention. However, for ease of description, the preferred embodiment uses pump pressure and entrained gas as a technique. This embodiment is not meant to li the scope of the present invention.

Supersaturation increases the concentration ofozone and oxygen in the liquid mixture beyond that which would be predicted by Henry's Law. Supersaturated, pressurized fluid is contacted with the pressurized catalytic reactor at the bottom of t reactor tank. The supersaturated water is forced to flow up through a granule suppor plate perforated with a multitude of small, fluid permeable holes and then through the fluid-permeable catalyst bed.

Because ozone is approximately thirteen (13) times more soluble in water than oxygen, as the ozone catalytically decomposes to oxygen, microscopic bubbles are created on the individual granule's surfaces. This oxygen occludes on the granule and, depending upon the size of the granule and the amount of static pressure on the syste (e.g., at pressures below about 10 psig), causes the granule to float up and out of the bed. At pressures greater than about 10 psig, the oxygen released by the catalytic destruction ofozone remains supersaturated and, therefore, does not occlude to the granule. In this manner, the catalyst bed remains totally within the reactor. One skille in the art would recognize that the size, shape and density of the granules, the fluid density, velocity, viscosity and temperature are among the parameters which affect the critical pressure where undesirable "lifting" bubbles are first able to form. Therefore, 1 psig is simply an example of one transition pressure suitable for one set of conditions.

To completely simplify the catalytic ozonation process, the transition pressure must be experimentally determined. A proper transition pressure could be readily calculated or determined by one skilled in the art with only ordinary experimentation. The reactor must be operated at pressures above this transition pressure. Because operation above the transition pressure prevents the formation of any gaseous oxygen, the reactor performs as a two-phase (liquid/solid) system. Therefore, the upstream extraction process must not over-deliver gas to the pump inlet. If over-delivery occurs, then there is a likelihood that cavitation will occur within the reactor. However, the use of a sight glass located at the pump discharge allows the operator to experimentally determine the extraction conditions which maximize ozone supersaturation without generating, via undesirable cavitation, visible bubbles in the pressurized effluent.

In another embodiment, an alternate way of determining whether gas is present in the reactor (from cavitation or improper parameter selection), is to survey the discharge orifice for audible "popping" sounds. When free gas (i.e., undissolved gas) is present at the discharge orifice, the gas expands rapidly as it meets suddenly reduced pressure once passing through the orifice. The rapid expansion of the gas produces an audible "popping" sound as two-phase fluid passes through the pressure control device. However, when free gas is not present, no audible "popping" can be heard. Applicant believes that the supersaturated gas evolves from the solution slowly (after the drop in pressure) and thus does expand at a rate capable of producing an audible "popping" sound.

The optimal operating conditions for the reactor are substantially at, but just below, the visible bubble stage. At these conditions, the decontaminating fluid has the ma imum practical ozone concentration. Those skilled in the art could, with only routine experimentation, design two-phase fluid bed reactors that retain substantially all the catalytic granules in the reactor, even after the granules grind themselves into very fine particles. The prior art reactors, however, cannot achieve this because the presence of three phases (i.e., the presence of gas bubbles) creates turbulence as bubbles rose faster than the surrounding liquid. These bubbles then carry granule fines with them, thereby carrying catalyst out of the reactor vessel. Prior art practitioners then had to attempt to recapture the fines, dispose and replace or recycle fines, or attempt to hold the catalyst in filter bags and distribute fluid through the filter bags. The simple process of the present invention substantially eliminates all of this unnecessary complexity and efficiently solves the problems of the prior art systems. Referring now to Figure 1, the present invention provides a reactor system 10 for decontaminating a supply of contaminated liquid F. The reactor system 100 comprises a pressurizable reaction vessel 200 having a means for introducing a fluid 102. This means for introducing a fluid 102 may be made of any suitable material, su as metal or plastic, and may be shaped in a variety of shapes, such as a pipe.

The reactor system 100 also has a means for expelling a fluid 104 while retaini a pressure within the vessel 200. This means 104 must be capable of letting decontaminated fluid escape from the reaction vessel 200 while providing enough flo resistance to keep the pressure within the reaction vessel 200 at a suitable level.

Inside the reaction vessel 200 is a catalyst 106 and a means for retaining the catalyst 108 within the vessel 200. For instance, a granular catalyst 106 may be place upon a perforated plate 108, where the perforations (not shown) are large enough to permit substantially unrestricted flow of fluid therethrough while preventing the cataly 106 from occluding the means for introducing a fluid 102.

The reactor system 100 further uses a pump 110 in fluid connection with the means for introducing a fluid 102 into the reaction vessel 200. To this pump 110 is attached a supply of gas 112 in fluid communication therewith. This gas 112 is used, i combination with the catalyst 106, to decontaminate the liquid stream.

Operation of the reactor system 100 occurs in such a way that when the pump 110 is operated, the supplied gas 112 and the contaminated liquid F are intermixed. T gas liquid mixture is supplied under pressure to the means for introducing a fluid 102 into the reaction vessel 200. The pressure from the pump 110 is maintained within the reaction vessel 200 at a sufficient pressure within the reaction vessel 200 to prevent th formation of bubbles of the gas 112 within the reaction vessel 200. The means for expelling 104 must have sufficient flow resistance to maintain the pressure within the reaction vessel 200 while allowing decontaminated fluid to be expelled from the reacti vessel 200. In a further embodiment of the basic reactor system 100, a plurality of reaction vessels 200 and 200' may be fluidly connected in series to one another. Therefore, complete decontamination need not occur in a single stage. Instead, partially decontaminated fluid may be fed from one reaction vessel's (e.g., 200) means for expelling into the pump associated with the next reaction vessel (e.g., 200'). An additional supply of gas 112' is provided for this second reaction vessel 200*. Upon exiting the final reaction vessel (e.g., 200') in the embodiment of this system 100, the effluent may collected, recirculated or otherwise discharged.

In a preferred embodiment, the operating parameters of the reactor system 100 may be checked using a means for determining the presence or absence of free gas, 114 or 116, within the reaction vessel 200. The absence of free gas in the reaction vessel 200 is the most desirable operating condition. One such means 114 is a transparent portion, such as a viewing window, of said reaction vessel. Another such means 116 is a means for sensing a sound (also 116) and the sound sensing means 116 is located outside the reaction vessel 200', but in audio contact with the means for expelling a fluid 104' from the reaction vessel 200'. As pressurized liquid traverses the means for expelling 104', it is exposed to greatly reduced pressure. Free, but pressurized, gas bubbles tend to make an audible "popping" noise upon exposure to the reduced pressure. This popping can be detected with a means for sensing a sound 116. One such means 116 is a microphone (not shown) optionally in connection with an amplifier (not shown). The operator (not shown) can determine proper operating conditions w hin the reaction vessel 200 by listening for "popping" sounds.

Still referring to Figure 1, in a preferred embodiment, the means for expelling a fluid 104 while retaining pressure whhin the vessel 200 can be a fixed orifice plate 118. Such a plate 118 has a plurality of orifices 120 therethrough, with the number and diameter of the orifices 120 determined such that while pressurized fluid may escape through the orifices 120, the flow resistance created by the size of the orifices 120 is sufficient to retain a desired pressure inside the reaction vessel 200. Another means for expelling a fluid 104 while retaining pressure within the vessel 200 is a manually- operated valve (not shown). With such a valve, operation of the reactor system 100 occurs in batches, rather than continuously.

Depending upon the type of decontamination desired, various types of suppli gases 112 may be used. In a preferred embodiment, the supplied gas 112 is ozone ga Ozone gas (O₃) is known to those in the art as a powerful oxidizer and, when couple with a suitable catalytic material, is capable of degrading many organic contaminants. Another supplied gas 112 may be oxygen, which is less potent, but still effective as a decontaminating agent in the presence of an appropriate catalyst 106.

In the embodiment depicted in Figure 1, the catalyst 106 is granular. Howeve powdered catalysts (not shown), or catalysts of other shapes (not shown) are also use for practicing the present invention, so long as they may be retained in the reaction vessel 200 in such a way as to not occlude the means for introducing a fluid 102 into reaction vessel 200.

In a further preferred embodiment, the reactor system 100 can utilize a downstream granule capture and recovery device 122 in fluid communication with the means for expelling 104 a fluid while retaining pressure within the vessel 200. Thus, catalytic material inadvertently expelled from a reaction vessel 200 can be recovered a appropriately recycled to the interior (not shown) of the reaction vessel 200.

The reactor system 100 may be used in a general method of decontaminating a supply of contaminated liquid F. This method comprises the steps of first directing a supply of gas 112 and a supply of contaminated liquid F to a pump 110 in fluid communication with a pressurizable reaction vessel 200. The reaction vessel 200 has the parts described above. As stated above, this pump 110 is in fluid connection with the means for introducing a fluid 102 into the reaction vessel 200. Next, the pump 11 is operated so that the supplied gas 112 and the contaminated liquid F are intermixed and forced under pressure through the means for introducing a fluid 102 into the reaction vessel 200. The pump 110 must operate at a sufficient pressure so that, withi the reaction vessel 200, the pressure is high enough to prevent the formation of bubbles of the gas 112. The reactor system 100 is operated in this state for a period of time sufficient to decontaminate the liquid to a preselected level of decontamination.

The method can be practiced using a reactor system 100 having a plurality of reaction vessels 200, 200', etc. fluidly connected in series to one another, as described above.

In a preferred embodiment of the operating method, the further step of monitoring whether there are bubbles in the reaction vessel 200 can be accomplished using a means for determining the presence or absence of free gas (e.g., 114 or 116) within the reaction vessel 200. Such means are described above.

In another preferred embodiment, effluent (not shown) from the reactor vessel 200 can be passed through a downstream granule capture and recovery device 122 in fluid communication with the means for expelling a fluid 104 while retaining a pressure within the vessel 200. The recovered granular catalyst 106 can then be reintroduced to an appropriate reaction vessel 200.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

What is claimed is:

1. A reactor system for decontaminating a supply of contaminated liquid, comprising: a) a pressurizable reaction vessel having a means for introducing a fluid, a means for expelling a fluid while retaining a pressure within the vessel, catalyst, and a means for retaining the catalyst within the vessel; b) a pump in fluid connection with said means for introducing a fluid into said reaction vessel; and c) a supply of gas in fluid communication with said pump, whereby said pump is operated so that the supplied gas and the contaminated liquid intermixed and supplied under pressure to said means for introducing a fluid into the reaction vessel and whereby the pressurized gas and liqui mixture is maintained at a sufficient pressure within said reaction vessel to prevent the formation of bubbles of the gas within said reaction vess

2. The system of Claim 1, further comprising a plurality of said reaction vessels i fluid connection in series to one another.

3. The system of Claim 1 , further comprising a means for determining the presen or absence of free gas within said reaction vessel.

4. The system of Claim 3, wherein said means for determining is a transparent portion of said reaction vessel.

5. The system of Claim 3, wherein said means for determining is a means for sensing a sound and said means for sensing is located outside said reaction vessel, but in audio contact with said means for expelling a fluid from said reaction vessel.

6. The system of Claim 1, wherein said means for expelling a fluid while retaining pressure within said vessel comprises a fixed orifice plate.

7. The system of Claim 1, wherein said means for expelling a fluid while retaining a pressure within said vessel comprises a manually-operated valve.

8. The system of Claim 1, wherein said supplied gas is ozone gas.

9. The system of Claim 1, wherein said supplied gas is oxygen gas.

10. The system of Claim 1, wherein said catalyst is granular.

11. The system of Claim 10, further comprising a downstream granule capture and recovery device in fluid communication with said means for expelling a fluid while retaining a pressure within said vessel.

12. A method of decontaminating a supply of contaminated liquid, comprising the steps of: a) directing a supply of gas and the supply of contaminated liquid to a pump in fluid communication with a pressurizable reaction vessel having a means for introducing a fluid, a means for expelling a fluid while retaining a pressure whhin the vessel, a catalyst, and a means for retaining the catalyst within the vessel, wherein the pump is in fluid connection with said means for introducing a fluid into said reaction vessel; b) operating said pump so that said supplied gas and the contaminated liquid are intermixed and forced under pressure through said means for introducing a fluid into the reaction vessel at a sufficient pressure such that within said reaction vessel the pressure prevents the formation of bubbles of the gas; and c) operating said reactor system for a period of time sufficient to decontaminate the liquid to a preselected level of decontamination.

13. The method of Claim 12, further comprising a plurality of said reaction vessel fluid connection in series to one another.

14. The method of Claim 12, further comprising a means for determining the presence or absence of free gas within said reaction vessel.

15. The method of Claim 14, wherein said means for determining is a transparent portion of said reaction vessel.

16. The method of Claim 14, wherein said means for determining is a means for sensing a sound and said means for sensing is located outside said reaction vessel, but in audio contact with said means for expelling a fluid from said reaction vessel.

17. The method of Claim 12, wherein said means for expelling a fluid while retaini a pressure within said vessel comprises a fixed orifice plate.

18. The method of Claim 12, wherein said means for expelling a fluid while retaini a pressure within said vessel comprises a manually-operated valve.

19. The method of Claim 12, wherein said supplied gas is ozone gas.

20. The method of Claim 12, wherein said supplied gas is oxygen gas.

21. The method of Claim 12, wherein said catalyst is granular.

22. The method of Claim 21 , further comprising a downstream granule capture an recovery device in fluid communication with said means for expelling a fluid while retaining a pressure within said vessel.