Liquid purification or separation – Processes – Separating
Reexamination Certificate
1999-10-27
2001-04-10
Popovics, Robert (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S252000, C210S255000, C210S262000, C210S908000, C261S076000, C261S078200, C095S169000, C095S170000, C095S204000, C095S223000, C095S237000, C096S207000, C096S215000
Reexamination Certificate
active
06214242
ABSTRACT:
This invention relates to a method of and device for stripping volatile organic and similar compounds from a non-volatile liquid such as water that is contaminated with such compounds, in order to enable the liquid to be reused for purposes where any remaining contamination is acceptable for such use.
BACKGROUND OF THE INVENTION
Water has long been recognized as one of the earth's most precious resources. Recent scientific reports have indicated that the population of the earth may double by the year 2050, placing severe stress on the supply of fresh water available for human use, crops, livestock and other needs where only relatively clean water is acceptable to meet the requirements. In many areas, the demand for fresh water already exceeds the supply, and the situation is only expected to worsen. Desalinization is not always an option, because it ordinarily requires that a nearby source of salt water be available. Cost also continues to be comparatively excessive. Desalinization is customarily confined to areas where fresh water is either scarce or unavailable.
Many industrial uses of water result in contamination with volatile organic compounds (VOC's) such as oils, gasoline, benzene, etc., to the extent that the degraded water is no longer fit for other purposes. A number of methods of treatment of VOC-contaminated waste water have been in use for a considerable period. They typically involve aerating the waste water to cause separation of the VOC's from the water by providing for their molecular attachment to air, discharging the separated VOC's and air and letting the water flow by gravity or by being pumped to a collection point for the now-decontaminated liquid Examples of apparatus for practicing the method are illustrated in U.S. Pat. Nos. 4,544,488, 5,266,208, 5,470,478, 5,685,976 and 5,069,796. This prior art demonstrates various types of towers and tanks in which forced air is passed upwardly through descending water moving by gravity from one perforated, shallow tray to another or through a bed of particulate material, ordinarily by bubbling the air through the water from below to create a froth of the contaminant, and then separately collecting the then-contaminated air and decontaminated water. Other of these systems utilize charcoal or carbon to finally adsorb the last-remaining organic materials when the water is to be stripped completely of contaminants. Typically, while such systems are effective to one degree or another, they generally suffer to some extent from being labor-intensive in requiring frequent disassembly and cleaning and from being complex in structure. Obviously, decontamination of a processed liquid cannot be performed satisfactorily by equipment that collects contaminant internally during processing and retains some of the contaminating substance within the equipment after processing. None of the equipment of the above-mentioned prior art systems can be said to be self-cleaning.
Additionally, it is typical to provide demisting apparatus with conventional air strippers, increasing the overall cost of the equipment and necessitating that the demisting means also require periodic disassembly and cleaning.
SUMMARY OF THE INVENTION
A method of and apparatus for stripping a volatile compound from waste water combine a high velocity stream of air and water to create a spray at a first inlet to a first expansion chamber to volatize the compound and commences air/water blending, and thereafter recombine the water and air flow through a second and further successive expansion chambers while recreating a blended spray at each such chamber, whereby additional volatile compounds are released from the water at each stage to steadily reduce the contamination of the water as stripping progresses. The decontaminated water and volatile compound-laden air are automatically demisted and separately collected after exiting the last expansion chamber. The apparatus is essentially self-cleaning and thus requires only nominal, occasional maintenance. Down time for disassembly and cleaning of the equipment is essentially eliminated, but in any event, is kept to a minimum. The structure is such that, even in the occasional instances where cleaning is required, it can be accomplished easily, quickly and efficiently.
While demisting apparatus is ordinarily required at the collection point of air and water of prior art air stripping systems, I provide for automatic demisting of the air within a collection or separation chamber itself, thereby eliminating the need for a conventional large equipment stack for that purpose.
It is a principal object of this invention to provide an air stripping method and apparatus that operates to more effectively reduce organic contaminants from water than known systems.
A major benefit from this invention is achievement of the principal object with an apparatus which is essentially self-cleaning.
Another object is to provide an apparatus that can be easily constructed from conventional, relatively low cost materials, without requiring use of easily-cloggable, fine nozzles and orifices.
Still another object is to provide a single vertical air stripping tank which can be divided into a plurality of separate, individual expansion chambers by means of a drop-in unitary set of spaced and interconnected impingement and focusing plates.
Another object is to enable the construction of the primary apparatus of my invention either as a single tall vertical unit or a low sequentially-segmented unit in which short interconnected segments are arranged parallel horizontally and stacked vertically.
Other objects and advantages will become apparent from the following description, in which reference is made to the accompanying drawings.
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patent: 3616599 (1971-11-01), Burnham, Sr.
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patent: 4378978 (1983-04-01), Andersson et al.
patent: 4696739 (1987-09-01), Pedneault
patent: 4824445 (1989-04-01), Minkkinen
patent: 5470478 (1995-11-01), Leva
patent: 2088240 (1982-06-01), None
patent: 2223960 (1990-04-01), None
Popovics Robert
Weigl William
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