Method and apparatus for enriching a liquid with a gas

A liquid enriched with a high concentration of free gas, in particular, water enriched with free oxygen, is produced by mixing the gas and liquid in an overpressurized system to form a mixture and then abruptly reducing the pressure of the mixture. Alternatively, the pressure reduction may be accomplished using a series of pressure reduction containers which sequentially reduce the pressure on the gas-enriched liquid in a slow incremental fashion, thereby allowing a high concentration of free gas to be maintained within the liquid phase.

FIELD OF THE INVENTION 
The invention relates to a liquid enriched with an extraordinarily high 
concentration of a gas phase component, and in particular, to water 
enriched with a high concentration of oxygen gas. The invention further 
relates to a method of enriching a liquid with a gas so as to obtain a 
high concentration of the gas within the liquid. In particular, the 
invention relates to a method of enriching water with a high level of 
gaseous oxygen. The invention further relates to apparatuses for enriching 
a liquid with a high concentration of a gas, and in particular, for 
enriching water with an elevated concentration of gaseous oxygen. 
BACKGROUND OF THE INVENTION 
It is known that all of the vital functions contributing to the human 
metabolism require oxygen, and that it is necessary for the human organism 
to obtain sufficient oxygen through breathing. However, methods have been 
developed for purposefully supplying the human organism with an amount of 
oxygen in addition to that obtained through breathing. Such additional 
oxygen can be supplied for generally improving normal function and 
wellbeing, on the one hand, but can also be used particularly as a 
treatment, or as a supplement to treatments for sick individuals. To 
accomplish this, it is known to use enriched water, that is, water 
enriched with free, gaseous oxygen. 
In one known method of enriching water with gaseous oxygen, oxygen gas is 
supplied to water via a perlite disposed on the bottom of an open 
container that is filled with water. Perlite is a porous volcanic mineral. 
The oxygen is forced through the perlite at low pressure, and bubbles 
through the water in the container before subsequently escaping into the 
environment or the atmosphere at the liquid-air interface. Passing the 
oxygen through the water causes it to be enriched with oxygen. As a result 
of this enrichment, the concentration of "free" oxygen in the water is 
about 35 mg/L. The term `free`, as it is used here with respect to the 
oxygen gas, and throughout this application with respect to free gas, is 
meant to include gas molecules which are released within the liquid phase 
as their physical interactions with liquid molecules in the fluid are 
broken. 
This known method has some drawbacks, however. For example, the 
concentration of free oxygen obtained in the water is only about 35 mg/L, 
which is a relatively low amount. Furthermore, after bubbling through the 
liquid, a portion of the supplied oxygen escapes into the atmosphere and 
cannot be reused, thereby resulting in a high gas consumption for the 
amount of oxygen-enriched water that is actually obtained. 
While there may be beneficial effects to the human organism of using water 
enriched at the known, relatively low concentrations described above, 
better treatment results could be obtained if higher levels of oxygenation 
could be achieved. Further, if less oxygen were lost to the atmosphere, 
the costs of producing oxygen-enriched water could be reduced. 
Besides use for human consumption, for general well being and in 
therapeutic methods as referred to above, oxygen enriched water has other 
known uses, such as in water purification processes, cleaning processes, 
and the like. Further, it may be desirable to enrich other liquids with 
other gases for other uses, at higher concentrations than are currently 
achievable, and with less wasted gas during the process of enrichment. 
As discussed above, therefore, a need has existed for water more highly 
enriched with oxygen, a method of achieving the higher enrichment, and an 
apparatus for achieving the higher enrichment. A need has further existed 
for other liquid/gas-enriched products, as well as a method and apparatus 
for producing them. 
SUMMARY OF THE INVENTION 
It is a principal object of the present invention to meet the 
above-described needs and overcome the above-described drawbacks of the 
prior products, methods, and apparatus. 
In that regard, it is an object of the invention to provide an enriched 
fluid comprising a liquid phase having dispersed therein a high 
concentration of a gas phase component that is maintained within the 
liquid under normal storage conditions. In this enriched liquid, the 
concentration of free gas is over 60 mg/L. In particular, the liquid phase 
is water, and the gas phase component is oxygen. 
It is also an object of this invention to provide a method for enriching a 
liquid with gas such that the liquid has a high concentration of free gas, 
while simultaneously reducing the amount of gas consumed in the process of 
enrichment. 
It is a further object of the invention to provide an apparatus for 
enriching a liquid with a gas such that the liquid has a high 
concentration of free gas, and gas consumption is reduced. 
It is also a particular object of the invention to provide a method and an 
apparatus for producing water enriched with a high concentration of oxygen 
gas, this concentration being higher than those previously achieved in the 
art, while simultaneously reducing the amount of oxygen consumed. 
The objectives stated above are accomplished in accordance with the 
invention by first enriching a liquid with a gas in a closed overpressure 
system, and following the enriching of the liquid, abruptly expanding the 
gas-enriched liquid by subjecting it to an abrupt drop in pressure. In the 
invention, because the gas is supplied to the liquid in a closed 
overpressure system, any excess gas is prevented from escaping from the 
liquid into the open atmosphere, and can be recaptured for subsequent use 
in further enrichment of the liquid. According to a further aspect of the 
invention, any excess gas that does not enrich the liquid during a first 
enriching process, remains inside the overpressure system, and can 
advantageously be reused at least once in the enriching process. 
Supplying the gas to the liquid under pressure effects an enrichment of gas 
in the liquid. This enrichment occurs under high pressure, and is 
primarily accomplished during the supply of gas to the liquid. The gas is 
maintained in the liquid by means of a close spatial connection or 
physical "bond" between the molecules of the gas and the liquid. However, 
the high concentration of free gas in the liquid is not obtained merely by 
introducing the gas into the liquid. Rather, the high concentration of 
free gas in the gas-enriched liquid is achieved by creating a rapid drop 
in pressure, for example, by conducting the gas-enriched liquid out of the 
overpressure system into a lower pressure area where abrupt expansion 
occurs. The gas-enriched liquid then expands because of the lowered 
pressure. As the gas-enriched liquid expands, the gas molecules that were 
physically bonded to the liquid molecules in the overpressure system are 
released. This release increases the concentration of free gas in the 
liquid, e.g., free oxygen in water. 
By using the novel practice of this invention, liquids enriched with 
concentrations of over 60 mg/L, and preferably, over 140 mg/L of free gas 
may be obtained. Most preferably, the amount of free gas is over about 200 
mg/L. These concentrations were not previously obtained using the 
gas-enrichment processes known in the prior art. 
According to one embodiment of the invention, gas-enriched liquid is 
conducted out of the closed overpressure system which can be selectively 
set to effect an accelerated, practically immediate expansion. This 
immediate expansion generates an especially high concentration of free gas 
in the liquid. It has been determined that the rapidity of expansion and 
the attainable concentration of free gas are directly proportional, so 
that the faster the expansion, the higher the concentration of free gas 
that is obtained in the enriched liquid. Therefore, by setting the rate of 
expansion of the gas-enriched liquid, the desired concentration of free 
gas in the liquid may advantageously be selected. 
According to another embodiment of the invention, the gas-enriched liquid 
that is conducted away from the closed overpressure system is expanded in 
a lower pressure system provided with an outlet, with a pressure drop 
occurring along the path of this transfer due to the different pressures 
dominating the overpressure system and the lower pressure system. This 
lower pressure system comprises one or more pressure release vessels or 
containers in series, each having at least one outlet. Where the lower 
pressure system comprises more than one pressure release vessel, the gas 
enriched liquid and headspace gas move from one vessel to another via the 
one or more outlets. As the gas-enriched liquid is conducted through this 
pressure drop, it expands, causing the gas in the liquid to be freed. The 
pressure ratios in the closed overpressure system and the lower pressure 
system having the outlet can be set, preferably so as to depend on one 
another. For example in a preferred embodiment, the pressure in the closed 
overpressure system can be set in the range of about 1.5 to 6 bar, while 
the pressure in the lower pressure system having the outlet can be set in 
the range of about 0.2 to 2.5 bar. The pressures are set so that a 
distinct pressure drop occurs in the gas-enriched liquid moving between 
the two systems, leading to an expansion of the liquid during which the 
gas is released. 
In one aspect of this preferred embodiment of the invention, the liquid is 
moved from the closed overpressure system into a lower pressure system 
comprising a pressure release vessel having an outlet. During the 
transfer, this lower pressure system is maintained at the same pressure as 
the pressure in the closed overpressure system. After this transfer to the 
outletted vessel at a constant pressure, the pressure in that container is 
subsequently reduced in small increments. As a result, there is no rapid 
expansion of the fluid; rather it is allowed to expand in slow, 
incremental fashion. Once the liquid is moved to the pressure release 
vessel having an outlet, the pressure in that vessel is then decoupled or 
cut off from the closed overpressure system with respect to the pressure 
ratios between them, and the pressure in the lower pressure system is 
reduced slowly. In the process, the gas-enriched liquid expands slowly. 
During the slow expansion of the fluid, the gas is not liberated in the 
form of small bubbles inside the liquid to the same extent as occurs with 
the abrupt expansion. More of the gas molecules remain tightly bonded to 
the liquid, and as a result, the gas remains in the liquid longer. This 
property is especially evident when the gas-enriched liquid is filled into 
a container such as a tank. When stored in such containers even over long 
periods of time, for example several weeks, the gas is not liberated. The 
gas is also not liberated when the liquid is transported in such 
containers and exposed to jarring motions. 
In this preferred embodiment, the pressure in the lower pressure system 
having the outlet is reduced to a pressure of, for example, one bar. The 
reduction in pressure to this level ensures the slow expansion of the 
liquid with only a small-scale release of the gas dissolved therein. The 
pressure in this system can be reduced until it closely corresponds to the 
external or atmospheric pressure outside of the pressure system. The 
system is then effectively depressurized. Under these static conditions, 
the liquid can then be conducted out of the pressure system and filled 
into containers such as tanks. Once the pressure vessel is emptied, it may 
again be subjected to the elevated pressure level of the closed 
overpressure system and refilled with more gas-enriched liquid from that 
first phase of the process. In effect, the pressure system having an 
outlet operates as a pressure lock that enables transfer of portions of 
the liquid volume out of the closed pressure system into a system which 
exposes the gas-enriched liquid to a pressure gradient, thereby 
stabilizing the fluid system. As a result, the amount of free gas 
contained in the liquid product is increased. 
In another aspect of this embodiment, the apparatus includes a reservoir 
container for holding a liquid, which is connected to a high-pressure gas 
supply line to form a closed overpressure system. Closure or blocking 
mechanisms, such as sliding valves, are provided in the lines connecting 
the reservoir container and the gas supply source. 
The reservoir container is further connected to conduct gas-enriched liquid 
to a chamber having a pressure that is lower in comparison to the 
reservoir container, which connection can be opened and closed 
selectively. A pressure regulator at the high-pressure gas supply can be 
used to adjust the pressure in the closed overpressure system. 
According to another aspect of the apparatus, a lower portion of the 
container holds the liquid and the gas is supplied to an upper portion of 
the container. An external enrichment arrangement in the form of a closed 
loop is provided, having a first line connected to the container for 
drawing gas from the upper portion; a second line connected to the 
container for drawing liquid from the lower portion; a junction for 
combining the first and second lines into a common line carrying both 
liquid and gas; a supply device for receiving the liquid and gas from the 
common line and performing a first mixing to form a gas-enriched liquid; 
and a swirling device connected to an output of the supply device for 
performing a second mixing and providing gas-enriched liquid back to the 
container at an upper portion thereof. 
Instead of the external enrichment arrangement closed loop where the liquid 
is enriched with gas outside the reservoir container, an internal 
enrichment device, i.e., internal to the container, may be provided, 
according to an alternate embodiment. Likewise, there could be separate 
containers for unenriched liquid and the gas-enriched liquid instead of 
the one container, according to an alternative embodiment. 
According to further aspects of the invention, the supply device is a 
centrifugal pump, the swirling device is a cyclone swirling chamber in 
which a net, screen or the like can be additionally installed, and the 
container has an overpressure release valve at a top thereof. The 
centrifugal pump may include a high-pressure injector. 
According to another aspect of the invention, adjustable valves, e.g., 
sliding valves, are provided on the first line, the second line and 
between the swirling device and the container, to control the flow of gas, 
liquid and gas-enriched liquid through the enrichment arrangement closed 
loop. Pressure sensing devices, pressure sensors, are also provided in the 
common line and at the output of the supply device, for example, as well 
as at the container, for sensing the respective pressures. Adjustment of 
the valves may also be used to obtain the desired pressures as measured by 
the pressure sensors. 
According to a further aspect of the invention, the chamber having a 
pressure that is lower in comparison to the reservoir container comprises 
a hollow ball valve, having slot-shaped openings which can be opened and 
closed, on a line leading from the container to the chamber. A pressure 
sensor measures the pressure inside the hollow ball valve. Pressure and 
flow speed sensors are provided at an outlet from the hollow ball valve, 
along with a gas measurement sensor for detecting the amount of free gas 
in liquid thereat. 
The sensors and valves may form part of an automatic control system 
operated by a digital computer, for example, whereby desired levels of 
gas-enrichment may be set and conveniently monitored, based on pressures 
and flows in the apparatus. Alternatively, the system may be manually 
adjusted by manual actuation of the valves based on manual reading of the 
sensors' indications. 
According to an aspect of the invention, the gas and the liquid are mixed 
in the supply device, and in the process, the liquid is enriched with the 
gas in the above-described manner, such that the gas is bonded to the 
liquid. That is, a measurably high concentration of "free" gas in the 
liquid has not yet been attained. The gas-enriched liquid is returned to 
the reservoir container following the mixing process. The chamber in which 
the dominating pressure is lower in comparison to the reservoir container 
is connected to the reservoir container to receive liquid therefrom. The 
connection is embodied such that it can be opened and closed. When opened, 
gas-enriched liquid exits the reservoir container and enters the chamber 
due to the different pressure ratios. The gas-enriched liquid is expanded 
according to the invention, and the gas that was previously bonded in the 
liquid is freed. 
Another preferred embodiment of the invention is characterized by an 
apparatus in which the liquid is moved from the closed overpressure system 
into a lower pressure system comprising a series of pressure reduction 
containers used to lower the pressure of the gas-enriched liquid. This 
embodiment comprises a supply device for supplying the gas to the liquid, 
a reservoir for the gas-enriched liquid; and a connection between the 
reservoir and the supply device to form a closed overpressure system. In 
addition, the lower pressure system includes at least one pressure 
reduction vessel or container whose internal pressures can be set at 
different levels to create a pressure gradient over the direction of flow 
of the gas-enriched liquid. Each of the pressure reduction containers may 
be closed or otherwise controlled with a cut-off mechanism. 
In this embodiment, the lower region of the first pressure reduction 
container is connected to the reservoir container to allow passage of the 
gas-enriched liquid. This connection is fitted with a closure means that 
allows the passage of the gas-enriched liquid to be controlled or blocked. 
The liquid level in the reservoir container is maintained at a volume 
level that is higher than the level in the pressure container. The 
difference in hydrostatic pressure allows movement of the gas-enriched 
liquid from the reservoir container to the pressure reduction container. 
This is advantageous in that a pump or other motion-based device is not 
required to move the liquid. 
As the gas-enriched liquid moves through the system, the conditions in the 
pressure reduction container are maintained so as to prevent a decrease in 
pressure, which would result in release of the gas. To maintain these 
static conditions, the pressure reduction container is directly connected 
to the source of the gas, for example an external gas tank as previously 
described. This gas supply source is an integral component of the closed 
overpressure system, which also includes the reservoir container. The 
connection to the gas supply source provides a means of equalizing the 
pressure between the reservoir container and the pressure reduction 
container before the gas-enriched liquid is moved into the pressure 
reduction container. Once this equal pressure has been established, the 
connection to the gas supply source is closed, and the block between the 
reservoir container and the pressure reduction container is removed. 
Because of the difference in volume levels, a portion of the liquid in the 
reservoir container is transported by hydrostatic pressure out into the 
pressure reduction container. This liquid is advantageously not subject to 
any changes in pressure during this transfer process, and therefore no 
bound gas in the liquid is released. 
After the pressure reduction vessel is filled, the input connection from 
the reservoir vessel is closed, and the gradual pressure reduction begins. 
A pressure discharge valve is preferably situated in the pressure 
reduction container, most preferably in the upper region. This pressure 
discharge valve is used to reduce the overpressure in the pressure 
reduction container at a slow, incremental pace. A manometer may be 
disposed within the pressure reduction container to monitor the rate of 
pressure change. 
The pressure reduction container is further equipped with a liquid outlet 
to allow collection of the gas-enriched liquid into storage containers 
once the pressure in the pressure reduction container has been reduced to 
atmospheric pressure. 
In a further preferred embodiment, the reservoir container and the gas 
supply of the overpressure system may be connected to a lower pressure 
system comprising a series of two pressure reduction containers. These are 
in turn connected to each other by a gas-pressure equalization line, which 
can be blocked by means of a pressure discharge valve. 
Gas and gas-enriched liquid can thus alternately be supplied from either 
the reservoir container or the gas supply into either of these pressure 
reduction containers. By using this series of pressure reduction vessels, 
the volume of liquid that can be processed by the apparatuses of the 
invention is increased significantly. 
In another aspect of this embodiment, a liquid-level regulating device is 
provided to monitor the level of the gas-enriched liquid in the reservoir 
container. This device is advantageously used to ensure that a sufficient 
liquid volume is always present in the reservoir container, to permit 
continuous filling of the one or more pressure reduction containers 
according to the invention. 
Alternatively, more than two pressure reduction containers may be used in 
sequence. The volume capacity of the reservoir container should however be 
of a correspondingly increased dimension to provide adequate input to the 
pressure reduction vessels. Transfer of the gas-enriched liquid through 
the system of pressure reduction vessels is accomplished in stepwise 
fashion. The first vessel is brought to the same pressure as the reservoir 
container by introduction of the supply gas, and is then filled with 
liquid. The pressurized gas fills the headspace above the liquid in the 
pressure reduction vessel. Any free headspace gas present in this first 
pressure reduction vessel as a result of the overpressure in the reservoir 
is then introduced to the next pressure reduction vessel in the series via 
the gas-equalization line when the pressure discharge valve is opened. An 
advantage of this arrangement is that no additional supply of gas is 
necessary for building the pressure in the remaining pressure reduction 
vessels in the sequence once the pressure has been adjusted in the first 
vessel. Rather, gas that has been used in one of the pressure reduction 
vessels can also be used in the other pressure reduction vessels, thereby 
enabling consumption of gas to be maximized. 
The apparatus of the invention can preferably be operated continuously, 
thereby allowing continuous removal of gas-enriched liquid from the one or 
more pressure reduction containers. 
Regardless of which embodiment of the pressure-adjusting apparatus is used, 
the reservoir container may be embodied as a tank, for example, that is 
initially filled, in the absence of pressure, to about 2/3 capacity with 
the liquid. The gas intended to enrich the liquid is introduced into the 
upper third of the tank. The gas is introduced under high pressure, and 
the tank, along with adjacent enrichment components, form a closed 
overpressure system. Water, for example, is used as the liquid, and oxygen 
supplied from a commercially available, high-pressure oxygen source is 
supplied as the gas. The pressure in the closed overpressure system can be 
adjusted with a pressure regulator provided at the oxygen source, as well 
as with a pressure relief valve provided on the reservoir container tank. 
As mentioned above, the liquid and the gas can be mixed by, for example, a 
supply device disposed in the container. However, in the preferred 
embodiment, the reservoir container is connected via a closed loop system 
to conduct liquid and gas to an external supply device, in which they are 
mixed together, resulting in the bonded enrichment of the liquid with the 
gas. As already mentioned, in an embodiment, the supply device is 
preferably a centrifugal pump having a high-pressure injector, which is 
connected via a closed loop system to the reservoir container. A 
centrifugal pump having a high-pressure injector is capable of suctioning 
and further conducting a gas in addition to a liquid, or a liquid/gas 
mixture. The centrifugal pump suctions liquid and gas, and swirls them 
together as they pass quickly through the pump. Thus, the liquid is 
enriched with the gas, but this is a bonded enrichment; in other words, a 
close (strong) bonding of the gas to the liquid is achieved. 
According to an aspect of the invention, on the suctioning side of the 
centrifugal pump, the loop system includes a gas line that exits the upper 
region of the reservoir container, and a liquid line that exits the lower 
region of the reservoir container, the lines being guided to a common line 
directly in front of the centrifugal pump. The gas line and the liquid 
line are connected to the reservoir container such that they can remove 
gas and liquid, respectively, from the different regions of the reservoir 
container. Because these lines are guided together to a common line, a 
liquid/gas mixture is supplied to the centrifugal pump. A vacuum is 
simultaneously formed in the gas line, for example, due to the suction of 
the liquid through the centrifugal pump. A suction of the gas through the 
centrifugal pump is therefore simultaneously achieved. On the discharge 
side of the centrifugal pump, a swirling device may be disposed in a line 
between the centrifugal pump and the reservoir container. A further mixing 
of liquid and gas can advantageously be achieved with the swirling device. 
A cyclone swirling chamber, for example, in which a net, a screen or the 
like can additionally be installed, can be used as a swirling device. As 
the gas-enriched liquid passes through the device, it is swirled, 
effecting further mixing of the liquid and the gas. An advantage of this 
embodiment is that the degree of enrichment of the gas in the liquid is 
increased. The swirling device simultaneously represents a 
pressure-reducing device. While a vacuum exists on the suction side of the 
supply device, causing the media of gas and liquid to be auctioned into 
the supply device, an overpressure exists on the other side of the supply 
device. This overpressure can be reduced in the swirling device. This is 
achieved, for example, by an effective widening of the cross section of 
the line between the supply device and the container in the swirling 
device. 
According to an exemplary embodiment of the invention, the chamber having a 
lower pressure than the reservoir container comprises a hollow ball valve 
that is disposed in a line for gas-enriched liquid leading out of the 
reservoir container. The interior of the hollow ball valve forms a 
pressure system having an outlet. Inside its hollow ball, the hollow ball 
valve has a space in which a specific pressure can be realized, thereby 
allowing the ball to open or close the valve outlet. The pressure 
dominating here is significantly less than the pressure in the 
overpressure system of the reservoir container. The pressure drop is 
achieved because when the valve is in the closed position, the interior of 
the hollow ball valve is cut off from overpressure system. To allow entry 
of the gas-enriched liquid, the hollow ball valve is only opened slightly, 
forming a very narrow, nozzle-shaped opening. The openings for the passage 
of the liquid, which are formed between the interior of the hollow ball 
valve and the lines that lead away when the valve opens, are preferably 
slot-shaped. Because of this slot-shaped feature, the liquid is forced 
rapidly into the interior of the hollow ball valve under high pressure. 
The gas-enriched liquid enters the interior of which is under a 
substantially lower pressure, and can expand abruptly. According to the 
invention, during this expansion, the gas that was previously bonded to 
the liquid is converted into "free" gas in the liquid. This free gas in 
the liquid is a physically bonded gas that nevertheless forms no chemical 
compound with the molecules of the liquid, and is therefore "free." The 
hollow ball valve can be opened to a greater or lesser extent, which 
widens the slot-like opening between the interior of hollow ball valve and 
the lines leading away, so the pressure inside the hollow ball valve can 
thereby be set directly. To monitor the pressure, a pressure sensor 
(manometer) is also preferably disposed inside the hollow ball valve. A 
pressure sensor that measures and indicates the pressure dominating in the 
reservoir container is preferably associated with the reservoir container, 
as well. 
In a preferred embodiment, a flow-speed measurement device is disposed in a 
line that carries away gas-enriched liquid, downstream of the hollow ball 
valve in the flow direction of the liquid. In addition to the different 
pressures in the reservoir container and the inside of the hollow ball 
valve, the flow speed of the liquid through the hollow ball valve is a 
variable on which the concentration of the free gas in the liquid is 
dependent. This flow speed is monitored with the flow-speed measuring 
device. The value of the flow speed is a function of the set pressures and 
the size of the openings. Moreover, a gas measurement device, with which 
the concentration of free gas in the gas-enriched liquid can be measured 
and monitored, is disposed in the line that carries away the gas-enriched 
liquid, downstream of the hollow ball valve in the flow direction of the 
liquid. For optimum measurement by this gas measurement device, a specific 
liquid flow speed is set, which is monitored with the flow-speed 
measurement device. 
A line leading out of the hollow ball valve terminates in an outlet that 
can be opened and closed, and out of which liquid enriched with free gas 
can be removed. The liquid is drawn off, for example, into diffusion-tight 
containers. 
A gas-enriched liquid, in particular, water enriched with oxygen, which can 
be produced by the exemplary method and apparatus according to the 
invention, is advantageously characterized by a concentration of free gas 
of over 60 mg/L. In particular, water enriched in accordance with the 
invention may have a concentration of free oxygen of over 140 mg/L, and 
most particularly over 200 mg/L.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention will now be described in more detail by way of example with 
reference to the embodiment shown in the accompanying figure. It should be 
kept in mind that the following described embodiment is only presented by 
way of example and should not be construed as limiting the inventive 
concept to any particular physical configuration. 
The apparatus illustrated in FIG. 1 comprises a closed reservoir container 
1 for holding a gas-enriched liquid 2. Reservoir container 1 is provided 
with a pressure sensing and indicating device (manometer) 3 for displaying 
the pressure in reservoir container 1, and with an overpressure valve 4. 
Reservoir container 1 is connected to an enrichment arrangement, a closed 
loop system, for enriching a liquid with a gas. The enrichment loop 
includes a supply device 5 for mixing a gas with a liquid. Supply device 5 
comprises, for example, a centrifugal pump. On the intake side of the 
centrifugal pump supply device 5, a common line having a manometer 3 is 
provided for feeding a liquid and a gas to the pump 5 from the reservoir 
container 1. Gas line 6 leads away from the upper region of reservoir 
container 1, and liquid line 7 leads away from the lower region of 
reservoir container 1, these lines joining at the common line feeding the 
supply device 5 immediately upstream of supply device 5 in the flow 
direction. An adjustable slide valve 8 is disposed in liquid line 7, 
upstream of the joining point with gas line 6, and an adjustable slide 
valve 8 is provided in gas line 6, upstream of the joining point with 
liquid line 7. 
A line 9 for a gas/liquid mixture leads back to reservoir container 1 from 
supply device 5, so that the supply device 5 is disposed in a closed loop. 
A swirling device 19 is disposed in line 9 between the supply device 5 and 
the reservoir container 1. This swirling device 19 can be, for example, a 
cyclone swirling chamber. A slide valve 8 is likewise disposed in line 9 
downstream of the swirling device 19. 
The gas that is used to enrich the liquid is stored in the upper region of 
reservoir container 1. The gas can be introduced into reservoir container 
1 via a line 11 from an external gas tank 10, for example. Gas tank 10 is 
a high-pressure gas tank having a pressure regulator 12 in line 11 at the 
outlet of the tank 10. The pressure of the gas in reservoir container 1, 
and therefore the closed system formed by reservoir system 1, supply 
device 5 and lines 6, 7 and 9, can be set to a desired overpressure value 
(e.g., a pressure greater than atmospheric pressure) with pressure 
regulator 12. For example, a pressure of 1.5 to 6.0 bars may be set. 
Overpressure relief valve 4 on container 1 also serves to control the 
pressure in the container 1 by preventing the pressure from exceeding a 
certain set value, for example. 
A line 13 for carrying gas-enriched liquid away from the reservoir 
container 1 is connected to the lower region of reservoir container 1. 
Line 13 leads to a chamber 14 in which the dominating pressure is lower 
than the dominating pressure in the reservoir container 1. This chamber is 
embodied by a schematically-illustrated hollow ball valve 14, for example, 
which is inserted into line 13. A manometer 3 associated with hollow ball 
valve 14 measures the pressure inside hollow ball valve 14. 
Further components are disposed in line 13, downstream of hollow ball valve 
14 in the flow direction. In particular, a flow-speed measurement device 
15 and the sensor 16 of a gas-measurement device 17 are disposed in line 
13. Line 13 ultimately terminates in an outlet 18, with which a manometer 
3 and a slide valve 8 are associated. 
The apparatus shown in the drawing is used for enriching a liquid with a 
gas according to the following method. A quantity of water is supplied to 
the container 1 absent pressure to a level of, for example, two-thirds 
fall. The gas is then supplied to container 1 to establish an overpressure 
environment therein to a pre-selected pressure. 
The gas and liquid now stored in reservoir container 1 at a selected 
overpressure are supplied via lines 6 and 7, respectively, to the common 
line and thereby to supply device 5. The two media, liquid and gas, are 
mixed in supply device 5. In the process, the liquid is enriched with the 
gas such that the gas is bonded to the liquid. The concentration of free 
gas, that is, only physically-bonded gas, in the liquid, however, is still 
low at this point. The liquid and gas are mixed further in the swirling 
device 19 disposed in line 9, and the further mixed liquid and gas is 
supplied back to reservoir container 1. In this way, the liquid and gas 
are mixed in a closed loop overpressure system comprising the reservoir 
container 1, the supply device 5, the swirling device 19, and lines 6, 7 
and 9. Since the system is closed, any excess gas which does not bond with 
the liquid will be advantageously contained in container 1 and be usable 
for further enrichment, according to an object of the invention. 
Subsequent to enrichment through the closed loop overpressure system, 
liquid 2 enriched with bonded gas is provided to the interior of hollow 
ball valve 14 via line 13. The liquid 2 is forced at high pressure through 
slot-like, narrow openings between the interior of hollow ball valve 14 
and line 13, as a result of the different pressures in reservoir container 
1 and hollow ball valve 14. As the gas-enriched (bonded) liquid 2 enters 
the lower pressure interior of hollow ball valve 14, it expands abruptly, 
thereby freeing the gas bonded in the liquid 2. Because of the abrupt 
expansion, concentrations of free gas in liquid 2 of over 60 mg/L can be 
attained. 
For example, if water is enriched with oxygen, a concentration over 200 
mg/l can be achieved according to the above-described apparatus and 
method. The expansion in hollow ball valve 14 is monitored by flow-speed 
measurement device 15 and the gas concentration is monitored by 
gas-measurement device 17 with sensor 16. The liquid enriched with free 
gas can be removed from the apparatus at outlet 18, and, for example, can 
be drawn off into transportable containers. 
FIG. 2 shows an alternative exemplary embodiment of an apparatus for 
executing the method of this invention, which incorporates at least one 
pressure-reduction container. In this embodiment, pressure-reduction 
containers 119 and 119' are disposed downstream of the reservoir container 
1 (not shown in FIG. 2). Both containers are connected to the reservoir 
container by way of liquid flow line 13, which terminates in the lower 
region of each container. Gas line 6' is connected to the reservoir 
container 1, and further connects the upper regions of the pressure 
reduction vessels 119 and 119' to permit gas flow between them. Sliding 
valves 8 are inserted into both liquid flow line 13 and gas flow line 6' 
as blocking elements for flow control. Liquid flow line 13 includes a 
branch 13', which leads to the second pressure reduction container 119'. 
This branch establishes a liquid conducting connection between the second 
pressure reduction container 119' and the reservoir container 1. This 
connection is maintained even if the liquid-conducting connection between 
the first pressure reduction container 119 and reservoir container 1 is 
broken by operation of the respective sliding valve 8. Line 13 terminates 
in an outlet 18. 
The two pressure reduction containers 119, 119' are also connected to one 
another, by way of a gas equalizer line 20, so as to conduct gas. Gas 
equalizer line 20 terminates in the upper region of each of the pressure 
reduction containers 119 and 119', respectively. A sliding valve 8 and a 
gas flow-through indicator 23 are disposed in the gas equalizer line 20. 
In addition, each pressure-reduction container 119 and 119' has a 
pressure-discharge valve 22 in this upper region. 
The two pressure reduction containers 119 and 119' are disposed spatially 
below the height of the liquid level in reservoir container 1. 
In this alternative embodiment as is shown in FIG. 2., it is intended that 
the release of gas in the liquid be prevented. In contrast to the first 
embodiment of the invention, the gas dissolved in the liquid is not to be 
released during the expansion of the liquid. Here, the gas is allowed to 
remain bonded to the liquid, so the liquid is particularly stable after it 
has been filled into containers and during transport. 
In this alternative embodiment, the reservoir container 1 (not shown) is 
under a specific overpressure. When the sliding valve 8 is opened, the 
first pressure reduction container 119 is filled with a gas by way of gas 
line 6', and thus brought under the same overpressure. The pressure ratios 
are read using manometer 3. After this pressure has been generated, the 
sliding valve 8 in gas line 6' is again closed. The sliding valves 8 in 
line 13 are then opened. Because of the hydrostatic pressure and the 
arrangement of pressure-reduction container 119 below the height of the 
liquid level in reservoir container 1, liquid 2 flows through line 13 into 
the first pressure reduction container 119. The liquid flows into this 
pressure reduction container 119 until an equal liquid level is attained 
between reservoir container 1 and pressure reduction container 119, with 
residual gas preferably remaining in the pressure reduction container 119. 
Afterward, sliding valves 8 in line 13 are again closed. When sliding valve 
8 in the upper region of container 119 is open, the gas that is still 
present is conducted out of this container and into the second 
pressure-reduction container 119' by way of gas-equalizer line 20. While 
the gas is being carried off, the pressure drops in the first 
pressure-reduction container 119. The gas is carried off slowly and 
incrementally, so the pressure reduction is effected in a correspondingly 
slow fashion. An abrupt expansion of the liquid in pressure-reduction 
container 119 is prevented; instead, the liquid expands slowly. The gas 
escapes from pressure-reduction container 119 until the desired low 
pressure has been established in this container. Sliding valve 8 in 
gas-equalizer line 20 is then closed, and the sliding valves 8 provided in 
line 13 between pressure-reduction container 119 and outlet valve 18 are 
opened. The liquid can now be carried off via outlet 18 and, for example, 
filled into tanks. 
While the liquid is being carried off from pressure-reduction container 
119, pressure reduction container 119' is simultaneously filled with 
liquid from reservoir container 1 in a corresponding manner. Previously, 
this pressure-reduction container 119' has been brought under the same 
high pressure as in reservoir container 1 with the gas from 
pressure-reduction container 119 and, possibly, with additional gas, via 
gas line 6'. Liquid is subsequently introduced into pressure-reduction 
container 119' via branch 13'. To reduce the pressure in this 
pressure-reduction container 119', gas-equalizer line 20 is re-opened, 
whereupon gas remaining in pressure-reduction container 119' can be 
introduced into the first pressure-reduction container 119. 
These alternating steps of filling and emptying the pressure-reduction 
containers 119, 119' can be effected continuously. This permits a 
continuous removal of liquid at outlet 18. A liquid-level regulating 
device, not shown in detail, in reservoir container 1 ensures that a 
liquid level necessary for producing the necessary hydrostatic pressure 
ratios is always present in reservoir container 1. 
With a corresponding increase in the volume of reservoir container 1, 
further pressure-reduction containers similar to 119, and 119' can be 
provided. 
The operation may be performed manually, or under the control of an 
automatic control system including a digital computer, for example, as 
would be apparent to one skilled in the art. It will be apparent to one 
skilled in the art that the manner of making and using the claimed 
invention has been adequately disclosed in the above-written description 
of the preferred embodiment taken together with the drawing. 
It will be understood that the above described preferred embodiment of the 
present invention is susceptible to various modifications, changes, and 
adaptations, and the same are intended to be comprehended within the 
meaning and range of equivalents of the appended claims. 
For example, instead of the external enrichment arrangement, an internal to 
the container enrichment arrangement could be used. Further, besides the 
hollow ball valve, other ways could be used for effecting the abrupt 
pressure drop, as would be apparent to one skilled in the art.