A DEVICE FOR CREATION OF AN OXIDATION AND PRECIPITATION ZONE OR A REDUCTION ZONE IN AN AQUIFER

Abstract: The invention refers to a device for creating in an aquifer an oxidation and precipitation zone or a reduction zone between a number of injection wells arranged around one or more extraction wells for purified water, said injection wells each comprising an outer water-pervious tube (1). For preventing such a device from being clogged the invention suggests that at the upper end of the outer tube (1) is mounted a circulation vessel (2) from which extends downwardly within the outer tube (1) a first conduit (3), ending at the height of the upper portion of the aquifer and provided with a pressure inlet means (5) so as to form an upper ejector, and a second conduit (4), which at its lower end supports an externally sealingly mounted balloon body (7), which is inflatable into sealing engagement with the inner surface of the outer tube (1), said second conduit closely above said body carrying a pressure inlet means (6), so as to form a second ejector.

Description: A Device for Creation of An Oxidation and Precipitation Zone or A Reduction Zone in an Aquifer. The present invention refers to a device for carrying- out of the process according to claim 1 of the publication print WO 92/00918, i.e. for creating in an aquifer an oxi¬ dation and precipitation zone or a reduction zone between a number of injection wells arranged around one or more ex¬ traction wells for purified water, which zone is intended for in situ precipitation or reduction of substances not desired in the ground water, the desired zone being created intermittently between each pair of adjacent injection wells by (i) introducing oxygen, oxygen-containing gas or an oxygen-releasing substance into the water in both wells when creating an oxidation and precipitation zone, or in¬ troducing into the water in both wells an oxygen-consuming substance when creating a reduction zone, and (ii) pumping the water in one of the wells from below upwards while pumping the water in the other well from above downwards whereby a circulation circuit is formed in the aquifer between the two wells, said injection wells each comprising an outer tube which at least at the ground-water carrying portion of its length is apertured and water-pervious. The prior device suggested according to the WO 92/00918 has shown to operate satisfactorily in a number of applica¬ tions . In some cases where the ground-water has been "troublesome" and severely mingled with conteminants it has turned out that the ejectors have become rather severely clogged such that the process has been slowed down. Par- ticularly the re-directing zones in the gaps between the various tubes have been clogged. The outer tube exhibits only one internal surface in contact with the water while the inner tube is surrounded by the "troublesome" water both internally and externally. In the annular spaces be¬ tween the tubes there are thus formed deposits both at the outer and inner surfaces so that they will be heavily clogged and the flow restricted. Furthermore, it has turned out to be difficult to flush away or otherwise get rid of said deposits due to the relatively small tube diameter of the injection wells. The object of the present invention thus is to elimi¬ nate said disadvantage by means of a differently designed device for this purpose. The invention is essentially dis¬ tinguished in that at the upper end of the outer tube is mounted a circulation vessel from which extends downwardly within the outer tube on one hand a first conduit, ending at the height of the upper portion of the aquifer and slightly above its mouth being provided with a pressure in¬ let means so as to form an upper ejector, and at the other a second conduit, which ends at or below the middle of the aquifer and at its lower end supporting an externally seal- ingly mounted balloon body, which is inflatable into seal¬ ing engagement with the inner surface of the outer tube, said second conduit closely above said body carrying a pressure inlet means, so as to form a second ejector, both pressure inlet means and the balloon body being connected with one or more suitable pressure sources. The invention will be described further below with ref¬ erence to the accompanying drawing, in which in Fig. 1 is illustrated a diagrammatic axial section through a pair of wells and Fig. 2 is a longitudinal section through a device according to the invention. In the drawings it is thus shown an outer tube 1 which preferably is cylindrical and introduced into the ground which at least in the ground-water carrying portion which starts at the ground-water level 11, and over portion of its length is apertured and thus water-permeable. In the upper portion of said tube 1 is at/or above the ground sur¬ face mounted a circulation vessel 2 from which extends downwardly within the outer tube 1 a first conduit 3 which ends at the height of the upper portion of the aquifer. Slightly above its mouth said conduit 3 is provided with a pressure inlet means 5 so as to form an upper ejector. Fur¬ thermore, downwardly within the outer tube 1 extends a sec¬ ond conduit 4, which ends at or below the middle of the ap¬ ertured portion of the tube 1 in the ground. In its lower portion said conduit carries an externally sealingly mounted balloon body 7 which is inflatable into sealing en¬ gagement with the inner surface of the outer tube 1. Slightly above the body 7 this second conduit 4 supports a pressure inlet means 6 so as to form a second ejector. Both pressure inlet means 5, 6 and the balloon body 7 are con¬ nected with suitable pressure sources. In the case of form¬ ing an oxidation zone said pressure fluids consist of air supplied from e.g. a compressor, while in a reduction proc¬ ess the pressure fluid for the ejectors consists of water or water solution from a suitable, not-illustrated pump, while the balloon body 7 still is connected with a source of pressurized air through a hose 10. The circulation vessel 2 has a smoothly rounded shape for improved through-flow and hence reduced risks for the occurrence of deposits on the inner surface of said vessel. The vessel 2 furthermore can be provided with a bent vent pipe 8 the opening cross section being controll¬ able by means of a valve device 9. The conduits 3 and 4 preferably consist to a great ex- tent of plastic hoses. Fig. 1 illustrates an example of the location of wells with well pipes A and B between which are to be formed an oxidation and precipitation zone or a reduction zone and in which tubes the inventive device now is intended to be used in order to create the desired and active circulation cir¬ cuits in the aquifer. The device described above operates as follows. Presup¬ posing that the balloon body 7 is inflated and thus seal- ingly engages the inner surface of the outer tube 1 pres- surized air or water is supplied to the upper ejector or pressure inlet means 5 and water is then pumped upwardly into the circulation vessel 2 for being deaerated. The out¬ let valve 9 of the vent pipe 8 of the vessel 2 is re¬ stricted to a suitable extent . The water then is pressed downwardly through the conduit 4 into the lower portion of the tube 1 below the balloon body 7. From there, the water is pressed into the surrounding ground. Inversely, air or water/water solution may be supplied at the lower ejector or pressure inlet means 6 for pressing water upwardly through the conduit 4 to the vessel 2 for being deaerated. The water then flows back through the con¬ duit 3 for being pressed out into the ground water in the ground above the body 7. Should non-desired deposits occur within the tube and the conduits 3 and 4, a flushing may easily be carried out after emptying the balloon body 7 of air.

Claims: C l a i m s 1. A device for carrying-out of the process according to claim 1 of the publication print WO 92/00918, i.e. for cre¬ ating in an aquifer an oxidation and precipitation zone or a reduction zone between a number of injection wells ar¬ ranged around one or more extraction wells for purified wa¬ ter, which zone is intended for in situ precipitation or reduction of substances not desired in the ground water, the desired zone being created intermittently between each pair of adjacent injection wells by (i) introducing oxygen, oxygen-containing gas or an oxygen-releasing substance into the water in both wells when creating an oxidation and pre- cipitation zone, or introducing into the water in both wells an oxygen-consuming substance when creating a reduc¬ tion zone, and (ii) pumping the water in one of the wells from below upwards while pumping the water in the other well from above downwards whereby a circulation circuit is formed in the aquifer between the two wells, said injec¬ tion wells each comprising an outer tube which at least at the ground-water-carrying portion of its length is aper- tured and water-pervious, c h a r a c t e r i z e d i n that at the upper end of the outer tube (1) is mounted a circulation vessel (2) from which extends downwardly within the outer tube (1) on one hand a first conduit (3) , ending at the height of the upper portion of the aquifer and slightly above its mouth being provided with a pressure in¬ let means (5) so as to form an upper ejector, and at the other a second conduit (4) , which ends at or below the middle of the aquifer and at its lower end supporting an externally sealingly mounted balloon body (7) , which is in¬ flatable into sealing engagement with the inner surface of the outer tube (1) , said second conduit closely above said body carrying a pressure inlet means (6) , so as to form a second ejector, both pressure inlet means (5, 6) and the balloon body (7) being connected with one or more suitable pressure sources. 2. A device according to claim 1, c h a r a c t e r i - z e d in that the circulation vessel (2) has smoothly rounded shape form improved through-flow and hence reduced risk of precipitations on the inner surface of the vessel. 3. A device according to claim 1 or 2, c h a r a c t e r ¬ i z e d i n that the circulation vessel (2) has a bent vent tube (8) , the mouth cross section being controllable by means of a valve device (9) . 4. A device according to any of claims 1-3, c h a r a c ¬ t e r i z e d i n that the conduits (3, 4) to a great portion of their length consist of a plastic hose. 5. A device according to any of claims 1-4, c h a r a c - t e r i z e d i n that in an oxidation process the pres¬ sure fluid consists of air which is supplied from a com¬ pressor while in a reduction process the pressure fluid to the inlet means (5, 6) consist of water or similar suitable fluid from a suitable pump.

Inventors: MARTINELL RUDOLF H, MARTINELL, RUDOLF, H.
Applicants: MARTINELL RUDOLF H, VYRMETODER AB, MARTINELL, RUDOLF, H.
Application year: 1996
Main classification: C02F1
IPC codes: B09C1, C02F1, E03B3