WO1996006799A1

WO1996006799A1 - Portable oxygen generator

Info

Publication number: WO1996006799A1
Application number: PCT/CA1995/000507
Authority: WO
Inventors: Tino Salonia
Original assignee: Geno2X Corp
Current assignee: Geno2X Corp
Priority date: 1994-08-31
Filing date: 1995-08-31
Publication date: 1996-03-07
Anticipated expiration: 1997-02-28
Also published as: CA2131266A1; AU3338895A

Abstract

A portable oxygen generating system using the principle of exothermic catalytic decomposition of an aqueous hydrogen peroxide comprising: a feed tank (1) having a mouth (10) to receive liquid hydrogen peroxide, a cap (12) to seal the mouth (10) during operation and an outlet pipe (3); an on/off valve (5) to control discharge from the feed tank; a regulator valve (7) to stop discharge from the feed tank when pressure in the system is equal to a predetermined pressure; a reactor (9) containing a catalyst of lead strips (30) in which hydrogen peroxide is decomposed; a cooling coil (13) to cool and condense the reaction products; a separator tank (17) to hold liquid water and gaseous oxygen: a return pipe (19) to the feed tank to balance pressure in the system; a drain (20) with a drain valve (21) to discharge water; and a product line (22) to supply oxygen for use by an operator of the system.

Description

Title Of The Invention

PORTABLE OXYGEN GENERATOR Technical Field

This invention relates to a portable oxygen generator and, in particular, a portable oxygen generator which produces gaseous oxygen by a process of decomposition of aqueous hydrogen peroxide using a catalyst of embossed metallic lead strips Background Art

Oxygen gas is used in scientific, medical and industrial procedures and there is a need for a relatively light and portable generating system. The development of a portable system has been disclosed in U. S. patent 4,792,435, entitled OXYGEN GENERATING SYSTEM which issued December 20, 1988 to Nakajima Do osho Company Limited of Tokyo, Japan in respect of an invention made by Nakajima, Masahiko, of Tokyo, Japan. As described in the abstract of this patent, the invention disclosed is an oxygen generating system for continuously generating oxygen gas by the catalytic decomposition of an aqueous hydrogen peroxide that includes a catalyst having a platinum group catalyst component earned on a highly porous sintered ceramic support of a large pore size and a reaction chamber for accommodating the catalyst. The system further includes a control device for controlling the operation of the hydrogen peroxide supplying based on a detection signal from a pressure sensor for detecting the pressure of the generated oxygen gas. The oxygen generating system is compact and reduced in weight due to the catalytic decomposition of hydrogen peroxide at high concentration, which can be earned out effectively and safely under an increased temperature.

Other relevant prior art includes U. S. patents:

3,887,696 6/1975 Bernard et al.

3,917,461 11/1975 Kuhl et al.

4,315,732 2/1982 Rowbottam et al.

4,466,556 8/1984 Sochting

4,488,951 12/1984 Nolan et al.

4,601,884 7/1986 Coeckelsberghs et al and Japanese patents.

42155 10/1977

26445 7/1978

49843 11/1981 and United Kingdom patent 2056310 dated 3/1981

Aqueous hydrogen peroxide is produces a large amount of oxygen per unit volume and is know as a means of reducing the size and the weight of an oxygen generator as compared, for example, to a high pressure oxygen gas cylinder. Japanese Utility Model Publication No. 26445/1980 discloses an oxygen gas generating system adapted to catalytically decompose aqueous hydrogen peroxide by using a manganese compound as a catalyst. This has been pointed out by Nakajima that the decomposing reaction proceeds explosively if the concentration of hydrogen peroxide exceeds about 5 w/w %. However, higher concentrations are necessary to achieve practical utility in a portable supply of aqueous hydrogen peroxide. A platinum type catalyst for decomposing aqueous hydrogen peroxide at a higher concentrations was disclosed in Japanese Patent Publication No. 42155/1977 However, Nakajima teaches that this catalyst is not satisfactory given the required reaction area and defoliation problems and that pnor to his patent that no effective practical means were available Thus, he teaches that the catalyst layer on the support tends to be deteπorated with the increase of the gas pressure inside the support and to be washed out by the aqueous hydrogen peroxide.

It is also known to have a system of controlling the flow rate of hydrogen peroxide by adjusting a valve for supplying aqueous hydrogen peroxide depending on the pressure of the generated oxygen gas by means of a mechanical link. (See Japanese Patent Publication No. 49843/1981). Nakajima discloses a pressure sensor for detecting the pressure of the oxygen gas and a water level sensor for detecting the water level in the gas/water separator attached to the separator. The sensors disclosed are semiconductor sensors or mechanical diaphragm sensors. A control unit controls a pump depending on the signal from the pressure sensor Disclosure of Invention The present invention provides an improved construction of a portable oxygen generator employing the pπnαple of the decomposition of hydrogen peroxide in the presence of a catalyst in a reactor. The system compπses a feed tank having an intake mouth to receive liquid hydrogen peroxide pnor to operation, a cap to seal the mouth duπng operation and an outlet pipe, an on\off valve to permit an operator to control discharge from the feed tank; a regulator valve to stop discharge from the feed tank when pressure in the system is equal to a predetermined pressure and to permit discharge when pressure in the system is less than said predetermined pressure; a reactor in which hydrogen peroxide is decomposed in the presence of a catalyst to oxygen and water, said reactor being in communication with said feed tank through said discharge pipe, said on\off valve and said regulator; a cooling coil in communication with said reactor to condense the water to a liquid and cool the oxygen from the reactor; a separator tank in communication with said cooling coil to receive an hold the liquid water and oxygen from the cooling coil and being in communication with the feed tank to balance pressure in the feed tank with the pressure in the separator tank; a drain leading from a bottom portion of said separator tank to discharge liquid water and having a drain valve to open or close said drain as may be desired from time to time; a product line leading from a portion of the separator tank above the anticipated level of liquid water to supply oxygen for use by an operator of the system.

The oxygen generating system preferably has a reactor pipe having a round cross section. The catalyst preferably compπses lead stπps and each lead stπp preferably has a rectangular cross section and a length approximately equal to the length of the reactor. The lead strips are laid longitudinally within the reactor and packed in juxtaposition across the cross section of the reactor to leave gaps between the lead strips for the flow of hydrogen peroxide and water and oxygen through the reactor. Brief Description of Drawings

In the figures which illustrate a preferred embodiment of this invention:

Figure 1 is a process flow diagram of the oxygen generator of this invention; Figure 2 illustrates a front sectional view of the oxygen generator;

Figure 3 illustrates a left side sectional view of the oxygen generator;

Figure 4 illustrates a right side sectional view of the oxygen generator;

Figure 5 illustrates a top sectional view of the oxygen generator;

Figure 6 illustrates a lead stnp used in a reactor of this invention; and Figure 7 illustrates a cross section of the reactor illustrating the packing of the lead strips within the reactor. Best Mode (or Modes) for Carrying Out the Invention

The flow diagram of Figure 1 may be referred to for understanding the general structure and operation of the invention. A feed tank (1) is filled with an aqueous hydrogen peroxide at a high concentration of about 35 % by weight. The hydrogen peroxide is fed by gravity through a pipe (3), a feed valve (5) and a regulator (7) to a reactor (9). The decomposition of the peroxide occurs in the reactor (9) so that water vapour and oxygen pass out of the reactor (9) through pipe (11) to the cooling coils (13). The cooling coils (13) condense the water to a liquid and the oxygen and water pass through pipe (15) into a separator or expansion tank (17) The liquid water collects in the base of the tank (17) and the oxygen fills the atmosphere of the tank (17). A return pile (19) permits the oxygen to recirculate to the feed tank (1) to pressurize the system. A draw off pipe (20) with an on\off valve (21) is provided to remove water from the system. A product pipe (22) with an on\off valve (23) is provided to draw off the oxygen for use. A pressure gauge (25) is provided on the product pipe (22) to measure the pressure of the oxygen being supplied to a user. Relief valves (27) and (29) are provided to protect against over pressuπng of the system. It will be understood by persons skilled in the art that all parts exposed to hydrogen peroxide will be constructed and passivated in a known manner to withstand pressures generated by the system and to avoid the corrosion.

The construction and layout of portable unit of this invention is shown in Figures 2-5. The operating equipment is contained in a housing (2) erected over a base (4) The base (4) supports all the equipment by means of conventional support structures generally depicted as (6) which are not descnbed further. A handle (8) is pivotally attached over the housing (2) to facilitate transportation of the unit.

Since the unit is intended to operate as a portable unit it is not designed to operate from a continuous supply of hydrogen peroxide although a person skilled in the art would be able to adapt the invention to a continuous supply. Consequently, the feed tank (1) has a wide mouth (10) so that liquid hydrogen peroxide may be poured into the tank (1) while the on\off valve (5) is closed. A screw cap (12) seals the mouth (10) of the feed tank (1) prior to operation. Further the product valve (23) and the drain valve (21) should be closed at the commencement of operation. Once the on off valve (5) is opened the peroxide is fed by gravity through pipe (3) and regulator (7) to the reactor (9) to decompose the peroxide to oxygen and water. As the water vapour and oxygen pass through the cooling coils (13), into the separator tank (17) and back along pipe (19) the pressure in the system begins to rise. The regulator valve (7) is preset to shut off the flow of hydrogen peroxide through pipe (3) to the reactor (9) at a predetermined operating pressure. Once flow is interrupted, the decomposition reaction stops and the system reaches equilibrium at the desired operating pressure The reactor (9) used in the preferred embodiment is a schedule 40 gauge pipe containing a catalyst of lead strips (30) (see Figure 6 and 7). Each end of the reactor (9) has a screw cap (14 and 16) to permit the reactor to be opened and closed to replace the lead strips (30). Each cap seals a reactor end about its respective connecting pipe when the system is operational. A screen (32) is provided within each cap to prevent the lead strips from sliding out of the reactor. As illustrated in Figure 6 the lead strips (30) are rectangular in cross section and about as long as the interior of the reactor (9). As shown in Figure 7 the strips (30) are packed longitudinally within the reactor (9) to fill its interior cross section insofar as rectangular strips may fill a round pipe. The gaps (34) between the strips (30) allow the peroxide to pass between them to effect decomposition in the presence of the lead catalyst. It may be determined when the strips are ready for replacement by the monitoring the reaction time of the system, i.e. how long it takes to reach operating pressure at start-up.

This invention is useful in medical, scientific and industrial applications where a portable source of oxygen is required. It will be appreciated by those skilled in the art that the description of the preferred embodiment is intended to be illustrative, rather than limiting of the construction and operation of this invention. Modifications and adaptations of this invention including the selection of materials and the layout of components may be determined by such skilled persons.

Claims

1. A portable oxygen generating system for generating oxygen gas in a batch process by the exothermic catalytic decomposition of an aqueous hydrogen peroxide comprising: a feed tank (1) having an intake mouth (10) to receive liquid hydrogen peroxide prior to operation, a cap (12) to seal the mouth (10) duπng operation and an outlet pipe

(3); an on\off valve (5) to stop discharge from the feed tank when the system is non-operational and to permit discharge when it is desired to make the system operational; a regulator valve (7) to stop discharge from the feed tank when pressure in the system is equal to a predetermined pressure and to permit discharge when pressure in the system is less than said predetermined pressure; a reactor (9) in which hydrogen peroxide is decomposed in the presence of a catalyst to oxygen and water, said reactor being in communication with said feed tank through said discharge pipe (3), said on\off valve (5) and said regulator (7), a cooling coil (13) in communication with said reactor to condense the water to a liquid and cool the oxygen from the reactor; a separator tank (17) in communication with said cooling coil to receive an hold the liquid water and oxygen from the cooling coil and being in communication with the feed tank to balance pressure in the feed tank with the pressure in the separator tank; a drain (20) leading from a bottom portion of said separator tank to discharge liquid water and having a drain valve (21) to open or close said drain as may be desired from time to time; a product line (22) leading from a portion of the separator tank above the anticipated level of liquid water to supply oxygen for use by an operator of the system.

2. The oxygen generating system of claim 1 in which the reactor is a pipe having a round cross section and the catalyst compnses lead strips (30), each lead stπp having a rectangular cross section and a length approximately equal to the length of the reactor, wherein said lead stπps are laid longitudinally within the reactor and packed in juxtaposition across the cross section of the reactor to leave gaps (34) between the lead strips for the flow of hydrogen peroxide and water and oxygen through the reactor.

3. The oxygen generator of claim 2 in which the reactor is capped at each end by screens (32) to retain the lead strips and removable caps (14 and 16) to permit replacement of the lead strips during non-operation and to seal the ends of the reactor during operation.