Irradiator For Water Purification

Abstract

An irradiator for sterilizing fluids, particularly contaminated effluents such as sewage. A housing is provided with a plurality of tubular partitions defining a flow path for causing sewage and the like to flow, alternately, back and forth past a series of source tubes containing radioactive material whereby the sewage provides shield means surrounding the radioactive source and becomes sterilized as it passes into and out of the housing.

Description

BACKGROUND OF THE INVENTION

It has been known for some time that radiation from a radioactive material is extremely dangerous because of its capability of destroying life. Lately, it has been recognized that this destructive capability can be advantageously utilized for destroying unwanted bacteria, viruses, spores and other types of microorganisms in addition to breaking down biodegradable material and non-biodegradable detergents.

Particular examples of the prior art are exemplified by U.S. Pat. No. 3,602,712 and U.S. Pat. No. 3,603,788.

SUMMARY OF THE INVENTION

The present invention relates to an irradiator for treating fluids and particularly for sterilizing liquids. The irradiator may be used as part of the final treatment of water prior to delivery thereof to the consumer, and also has particular advantages in treating effluents, such as raw sewage, as part of the final treatment prior to discharge of said sewage into streams, rivers and other bodies of water.

An object of the invention is to provide an irradiator for the treatment of fluids, particularly liquids, the apparatus including a housing having inlet and outlet ports for allowing passage of fluid therethrough, the housing being provided with means for locating a source of radioactive material therein and including flow path means for directing fluid to flow alternately in opposite directions for making a series of passes past the radioactive material for ensuring complete and proper sterilization.

Another object of the invention is to provide flow path means within the housing which comprise a plurality of individual plate members disposed in spaced relation to each other for defining a plurality of flow chambers, flow openings being provided in the plate members for interconnecting the flow chambers with each other.

A further object of the invention is the provision of providing plate members having a tubular configuration and being disposed concentrically within the housing, and providing flow openings in alternately opposite ends of adjacent ones of the partitions for interconnecting adjacent flow chambers together in such a manner that liquid flowing therein is subjected to turbulent flow to preclude sedimentation from accumulating within the flow chambers and also for ensuring substantially equal exposure of the fluid to radiation.

A still further object of the invention is to provide source tubes for radioactive material, the tubes being particularly constructed to provide access to the interior thereof without the necessity of interrupting liquid flow through the flow chambers.

Another object of the invention is to provide an irradiator which is particularly adapted for the use of cesium-137 as the source of radioactive material, this material being particularly useful because of its long half-life, its availability as a waste material from other processes, and the fact that it does not generate its own radioactive waste such as occurs with cobalt-60.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic, top plan view, showing the irradiator and associated pipes for moving fluid therethrough.

FIG. 2 is a vertical section taken on line 2--2 of FIG. 1.

FIG. 3 is a fragmentary perspective view of one tube-shaped partition forming part of the invention.

FIG. 4 is a fragmentary plan view, partly in section, showing a source tube for radioactive material and the manner that it is connected to the top plate of the irradiator.

FIG. 5 is a vertical section, taken on the line 5--5 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, an irradiator, generally indicated by the numeral 10, is, preferably, surrounded by shielding material 11 constructed of concrete, lead, or other types of known shielding material.

Irradiator 10 includes an outer housing 12 comprised of a tubular shell 14, a bottom cover plate 16 and a top cover plate 18. An inlet port 20 is centrally located in bottom cover plate 16 and an outlet port 22 is provided at an upper portion of housing 12 for allowing passage of fluid into and out of the housing. Fluid, such as raw sewage, is collected in a supply reservoir 24 from a supply pipe 26 after the sewage has, preferably, been filtered in a known manner for removing large solids therefrom.

As is shown in FIG. 2, the sewage to be treated flows, by gravity, through pipe 28 which leads to inlet port 20 at the bottom of the irradiator 10. The sewage is then caused to flow through irradiator 10, through flow path means which will be described hereinafter, until the sewage reaches outlet port 22 and continues through pipe 30 to a collection reservoir 32. The treated sewage may then pass through drain pipe 34, preferably to a final filter and subsequent discharge from the treatment system.

Fluid, such as water or sewage to be sterilized, passes through irradiator 10 along a tortuous flow path defined by a series of pipe members shown as being comprised of a series of six tube-shaped partitions 41, 42, 43, 44, 45 and 46 concentrically disposed within housing 12 and extending between bottom cover plate 16 and top cover plate 18.

As is exemplified by the showing of partition 41 in FIG. 3, each of the plate members or tube-shaped partitions 41-46 has one end portion thereof provided with a series of circumferentially spaced apertures or notches 50 located at the extreme end of the partition 41 and opening axially outwardly thereof. As is shown in FIG. 2, partitions 41, 43 and 45 are provided with such apertures or notches at the top end portion thereof adjacent top cover plate 18 while partitions 42, 44 and 46 are provided with such apertures or notches at their bottom end thereof adjacent bottom cover plate 16. As a result, a series of flow chambers are provided between adjacent ones of partitions 41-46 with an exit chamber 52 being provided between partition 46 and outer member 14 of housing 12, exit chamber 52 communicating with outlet port 22 so that treated fluid can pass through pipe 30 to collection reservoir 32. It is to be understood that apertures or notches 50 subject the fluid to turbulent flow not only at the top portion of housing 12 but also adjacent bottom cover plate 16 to provide homogeneous mixing of the fluid as well as precluding sedimentary deposits from building up on bottom plate 16.

Fluid passing through irradiator 10 is sterilized by being subjected to radiation from radioactive material 60 contained within a plurality of source tubes 62 which are shown in FIGS. 1 and 2 as being located to define a pair of inner and outer circular arrays of parallel tubes separated from each other by at least a pair of spaced plate members or partitions 42 and 43 which, as previously described, define a portion of the flow path through the housing 12. All of the source tubes 62 are constructed in like manner, the details of which will be apparent from a description of a particular source tube 63 as is shown in FIG. 5. Radioactive material 60 is packaged in a container 64 and a closed canister 66. A lifting pad 68 is located within source tube 63 and connected to a lifting plug 70 by at least a pair of cable members 72 so that the radioactive material 60 can be placed within or removed from the source tube. Lifting plug 70 is supported above top cover plate 18 by a pair of threaded collar members 74 and 76, the latter being welded, at 78, to the cover plate 18 thereby providing a closure cap, generally indicated by the numeral 80, for closing an opening 82 which is formed in cover plate 18 to allow source tube 63 to depend from cover plate 18 into the housing 12. Collar member 74 is fixedly connected to source tube 63, such as by welding or the like, so that the entire source tube 63 may be removed from housing 12 if found to be necessary or desirable.

While the invention is not so limited, it is preferred that radioactive material 60 consist of cesium-137. This material is particularly advantageous because of its relatively long half-life, its copius radiation, the fact that it is presently an undesirable waste material requiring expensive storage facilities, and the fact that it does not itself produce other radioactive wastes such as with cobalt-60.

Referring again to FIG. 2, it will be seen that irradiator 10 is preferably covered by a pool of water or other liquid shielding 86 which, for example, may be 6 to 10 feet deep and provide access to the closure cap 80 on the source tubes. In addition, lead lines 87 are readily connected between irradiator 10 and control equipment 88 which may be, for example, gamma ray monitors, meters, etc.

It is to be understood that the preferred embodiment herein disclosed is to be considered as exemplary of the invention and not as limitations thereof. For example, the plate members or partitions 41-46 have been shown as being circular in cross section but these partitions could also be formed as squares, rectangles or as flat plate members extending across a rectangular housing, all of which will provide a tortuous flow path for directing fluid in opposite directions past the source tubes and, simultaneously, allow the fluid being treated to provide shielding for the radioactive material with only a small amount of interference from the plate members or partitions.

While preferred forms and arrangement of parts have been shown in illustrating the invention, it is to be clearly understood that various changes in details and arrangement of parts may be made without departing from the spirit and scope of the invention, as defined in the appended claimed subject matter.

Claims

I claim:

1. Apparatus for irradiating fluids containing solids, said apparatus comprising a sealed housing having an inlet port and an outlet port for allowing flow of fluid into and out of said housing, shielding means enclosing said housing, said shielding means including a pool of water overlying said housing with said housing being viewable therethrough, said housing including a top wall readily accessible through said pool, said top wall having a plurality of openings therethrough, removable closures closing said openings, and a source of radioactive material carried by at least certain of said closures and positioned within said housing for irradiating fluid flowing through said housing, said removable plugs defining means for effecting the individual removal and replacement of said sources of radioactive material during the operation of the apparatus and while being shielded by said pool.

2. The apparatus of claim 1 wherein each opening is aligned with a source tube connected to said top wall and sealed relative to the interior of said housing, and each source of radioactive material is disposed within one of said source tubes and shielded from fluid within said housing thereby.

3. The apparatus of claim 2 wherein each source of radioactive material is depended from an associated one of said closures and is suspended in spaced relation to walls of said housing thereby.

4. The apparatus of claim 2 wherein each source of radioactive material is in the form of a capsule, a seat is suspended from an associated closure, and said capsule is seated on said seat for ease of removal and replacement within said pool.

5. The apparatus of claim 4 wherein cable means suspends each seat from a respective closure.

6. The apparatus of claim 1 wherein said housing therein has a plurality of baffles therein defining a predetermined flow path between said inlet port and said outlet port, said sources of radioactive material being disposed within said flow path for uniformly acting on all fluids passing thereby.

7. The apparatus of claim 1 wherein fluid flow through said housing is solely gravitational flow.

8. The apparatus of claim 1 wherein fluid flow through said housing is solely gravitational flow with there being a supply reservoir connected to said inlet port and a collection reservoir connected to said outlet port.