Liquefaction apparatus and method

Liquefaction apparatus and method for removing liquid molecules from a vaporous or gaseous medium, use being made of an annular porous layer (5) of van der Waals-type material through which the medium is radially outwardly directed, the layer being rotatably driven to discharge by centrifugal force the liquid modules that are bound by van der Waals forces in the layer. The layer is mounted concentrically on the inner periphery of a rotatably driven cylindrical separator member (4) having an annular wall portion provided with a passage system at least the outlet portion of which terminates in a plurality of radial passages (17) through which the liquid molecules are centrifugally discharged. In one embodiment, the separator member is cooled by a cooling bath (18) the liquid of which is recirculated through a refrigeration-type heat exchanger (12). In a second embodiment, a portion of the liquid condensate (14)in which the separator member is at least partially submerged is cooled by passage through a refrigeration-type heat exchanger (12).

STATEMENT OF THE INVENTION 
An apparatus and method are provided for the liquefaction of a vaporous or 
gaseous medium, use being made of an annular porous layer of a van der 
Waals-type material arranged concentrically on the inner periphery of the 
annular wall of a rotatably-driven cylindrical or cup-shaped separator 
member. The medium to be liquefied is conducted radially outwardly through 
the layer, those liquid molecules that are bound by van der Waals forces 
in the layer being discharged radially outwardly by centrifugal force from 
the separator via corresponding radial outlet passages formed therein. 
BRIEF DESCRIPTION OF THE PRIOR ART 
Liquefaction apparatus for vaporous or gaseous media are well known in the 
prior art. For example, there are known processes where -- for the 
liquefaction of vaporous or gaseous media or as an extraction device for 
vapor or gas mixtures -- use is made of compressors that work according to 
the displacement principle in order to suction off the particular vapors 
or gases and to condense them to liquefaction pressure. 
This applies in a similar manner to compression cooling circuits that are 
based on the cold vapor principle. 
Basically, however, these known processes are very cost-intensive as 
regards both as the equipment and the actual performance of the process. 
Furthermore, the energy expenditure is relatively high and that likewise 
is counterproductive in terms of optimum economic operation. 
Accordingly, the present invention was developed to provide a process by 
means of which one can suction off and liquefy many different vaporous or 
gaseous media with the least possible energy expenditure. 
SUMMARY OF THE INVENTION 
A primary object of the present invention is to provide a method and 
apparatus for the liquefaction of vaporous or gaseous media, use being 
made of an annular porous layer of a van der Waals-type material arranged 
concentrically within a rotatable driven cylindrical or cup-shaped 
separator member, whereby the liquid molecules found by van der Waals 
forces in the porous layer are discharged radially outwardly of the 
separator member for collection in a liquid condensate bed. 
In contrast to the known compression process based on the displacement 
principle, according to the present invention, no vapor or gas volumes are 
suctioned off and compressed. Instead, independently of the density or the 
specific volume of the vapor of gas to be liquefied, only the vapor or gas 
molecules are adsorptively bound by means of van der Waals shearing forces 
and are liquefied and, subsequently, along with simultaneous heat 
evacuation, are transported to a higher pressure level by means of the 
centrifugal forces appearing during rotation. Here, the process exploits 
the ability of the molecular sieve/drying agent to bind adsorptively the 
molecules of vapors of water or the like, or industrial gases, whereby the 
effect of these drying agents/molecular sieves is based on a very large 
active surface according to which the liquid molecules, as mentioned 
before, are retained by the van der Waals forces. As molecular sieves, one 
can use, for example, aluminum oxide or silicon oxide compounds. The 
drying agent can be made up of silica gel. 
Using this process, it is possible, in particular, also to achieve the 
oil-free liquefaction of vapors or gases with a large specific volume in 
the low-pressure range. In this way, one can, or example, in certain 
temperature ranges, replace the environmentally harmful FCKW refrigeration 
agents by means of water as refrigeration agent. 
The liquid molecules that are bound in a drying agent/molecular sieve ring 
are discharged radially outwardly by the centrifugal forces appearing 
during rotation, so that they exit on the outside of the ring. But this 
does not apply to vapor/gas molecules that are absorbed into the 
crystalline structure of the drying agent/molecular sieve. Assuming that 
the separator is arranged in a closed chamber, the pressure on the outside 
of the ring increases and finally becomes equal to or greater than the 
liquefaction pressure of the transported liquid molecules. Basically, the 
effect of the process rests on the fact that the occurring centrifugal 
forces during the rotation of the ring are greater than the van der Waals 
forces with which the liquid molecules are retained along the inside 
surface of the ring. 
According to a more specific object of the invention, heat removal means 
are provided for continuously cooling the separator, since because of 
their kinetic energy, the absorbed steam/gas molecules produce a warming 
of the annular porous layer that reduces its effectiveness. 
According to another object of the invention, the annular porous layer of 
van der Waals-type material is mounted concentrically on the inner surface 
of a rotatably-driven cylindrical or cup-shaped separator member that 
contains passage means affording communication between the inner and outer 
peripheral surfaces thereof. The separator member is formed of a material 
having good heat conductivity, means being provided for cooling at least 
part of the separator member to maintain the effectiveness of the annular 
porous layer. The passage means terminates in a plurality of radial 
passages through which liquid molecules entrained in the annular layer are 
discharged outwardly by centrifugal force upon rotation of the separator 
member. 
According to one embodiment of the invention, cooling of the 
rotatably-driven separator member is achieved by partially submerging the 
same in a cooling liquid bath, heat exchanger means being provided for 
removing heat from the cooling liquid. According to another embodiment, 
the rotatably-driven separator member is partially submerged in the liquid 
condensate both, whereupon a portion of the liquid condensation is cooled 
by a separate heat exchanger.

DETAILED DESCRIPTION 
Referring first more particularly to FIG. 1, the liquefaction system of the 
present invention includes a housing containing a low pressure chamber 7 
in which is mounted a cup-shaped or cylindrical separator 4 that is 
rotatably driven by an alternating-current motor 6. Arranged 
concentrically within the separator member 4 is an annular porous layer 5 
formed of a van der Waals-type material, such as aluminum, oxide or S 
lithium compounds. Alternatively, a drying agent -- such as a silica gel 
-- could be provided. The separator member contains a annular gap 13 that 
extends concentrically about the annular layer 5, which annular gap 13 is 
connected with the low pressure chamber 7 via passage means including 
longitudinal ducts 26, and a plurality of radially outwardly directed 
passages 17. Mounted in the passage means between the longitudinal 
portions 26 and the radial portions 17 are spring-biased relief valve 
means 25, respectively, whereby the gap 13 and longitudinal passages 26 
define a high-pressure chamber 8. The separator member 5 is rotatably 
driven by a drive motor 6 which, as shown in FIG. 2, is supplied with 
alternating-current power from source 22. In the embodiment of FIG. 2, the 
lower portion of the separator member 4 and the entire drive motor 6 are 
submerged in a cooling liquid bath 18, thereby to cool the exterior 
portion of the separator member and to maintain the efficiency of the 
annular porous layer 5. In order to increase the cooling effect, the 
submerged portion of the separator may be provided with annular cooling 
ribs 16. In the embodiment of FIGS. 2-4, vaporous or gaseous media within 
the low pressure chamber 7 is drawn by suction into the interior of the 
rotatably driven separator member 4, whereupon as the fluid passes 
radially outwardly through the annular layer 5, a number of liquid 
molecules are bound on the porous surfaces of the layer 5 owing to van der 
Waals forces. Owing to centrifugal force produced by the rotating 
separator member, the liquid molecules are thrown centrifugally out of the 
annular layer 5, and are introduced into the annular gap 13 of the 
high-pressure chamber 8, whereupon the relief valves 25 open when the 
pressure of the liquid molecules exceeds the closing force of the spring 
biasing means. Consequently, the liquid molecules are then discharged 
radially outwardly through the outlet passageway 17 owing to the 
centrifugal force produced by the rotating separator member 4. As shown in 
FIG. 2, the liquid molecules are collected in a return duct 21 having an 
annular portion at its upper end arranged concentrically about the radial 
passages 17. Liquid molecules collected in the upper portion of the return 
duct are then deposited downwardly through the conduit 21 toward the 
condensed liquid bath 14. 
In accordance with an important feature of the present invention, cooling 
liquid from the cooling chamber 18 is pumped by first pump means 9a to 
first heat exchanger means 10, which comprises a conventional 
refrigeration type system. The cooling liquid is then returned to the 
cooling chamber 18, so that the heat exchanger 10 removes the heat 
produced by the liquefaction process. Similarly, a portion of the liquid 
condensate in the liquid condensate bath 14 is removed via outlet 20 and 
is pumped by second pump means 9b through the heat exchanger 12, which 
heat exchanger is operable to heat the condensed liquid to its vaporous or 
gaseous state, whereupon the vaporous or gaseous medium is returned to the 
low pressure chamber 7 via the spray nozzle means 19. The vaporous or 
gaseous material is then drawn by suction upwardly through annular 
demisting means 15 arranged concentrically about the cooling chamber 18 
and the downwardly directed duct means 21. Thus, the demisting means 15 
prevent liquid molecules from being drawn upwardly for recirculation 
through the separator member 4. 
In the practical example shown in FIGS. 2-4, the high-pressure chamber 8 is 
formed by the annular gap 13 as well as boreholes 26, in that a pressure 
level is developed that is above the liquefaction pressure so that the 
exiting steam or gas molecules are liquefied into a condensate. 
High-pressure chamber 8 and low-pressure chamber 7 are separated by relief 
valves 25 that act as throttle means and that are arranged in the area of 
transition between boreholes 26 and openings 17. The annular demisting 
package 15 provided in low-pressure chamber 7 serves as a liquid droplet 
separator. 
OPERATION 
During practical operation, the entire system is first evacuated and the 
cooling liquid is filled into cooling chamber 18 or into the pipes 
belonging to the cooling circuit and the heat exchanger 10. Next, the 
vaporous medium, in this case, wet steam, is injected into the 
corresponding pipeline system, the utility heat exchanger 12, and 
low-pressure chamber 7. 
Simultaneously with the start of drive motor 6, circulating pumps 9b and 9a 
are operated, one of which transports the condensed liquid 14 located in 
low-pressure chamber 7 through utility heat exchanger 12, while the other 
one transports the cooling liquid to the heat exchanger 10. Partial 
evaporation takes place in utility heat exchanger 12 which, for example, 
comprises the structural component of an air conditioning system, with a 
steady heat supply going to that exchanger. The existing wet steam is 
suctioned inwardly via the open side of rotation cylinder 4 and is 
adsorbed and liquefied in ring 5 in certain proportions. 
Amid heat evacuation, the developing condensate is expanded on the way via 
boreholes 26 and relief valve 25, not shown in FIG. 3, to a return duct 
and is then supplied to low-pressure chamber 7. During the expansion 
phase, there is a partial evaporation of the condensate, in a manner 
similar to what happens in an expansion valve within a compression cooling 
circuit. 
Expansion takes place from liquefaction pressure toward evaporation 
pressure and the developing condensate is cooled from liquefaction 
temperature down to evaporation temperature and in the process again 
absorbs the internal energy of the water to be evaporated. 
The developing waste and condensation heat is given off to the air, water, 
gas or other media via the coolant and heat exchanger 10. 
To prevent the formation of droplets in the suctioning area of rotation 
cylinder 4, low-pressure chamber 7, as described before, contains the 
annular demisting package 15 arranged above the spray means 19 via which 
is supplied the wet steam generated in the utility heat exchanger 12. 
Referring now to the embodiment of FIG. 5, the system is a single substance 
system with direct heat evacuation of the separator member 4', as 
distinguished from the two-substance system of FIGS. 2-4. 
In this embodiment, the housing 3' includes a horizontal partition wall 24 
that separates the interior of the housing into an upper low-pressure 
chamber 7' and a lower high-pressure chamber 8'. The rotatably driven 
cup-shaped separator member 4' includes a neck portion 2 that extends 
upwardly through an opening contained in the horizontal partition 24, 
thereby to provide continuous communication between the low-pressure 
chamber 7' and the interior of the separator member. A gland or O-ring 
seal member 1 is arranged concentrically about the rotary neck portion 2, 
thereby to seal the upper and lower chambers 7' and 8' from each other. 
The interior of the separator member 4' is covered by the annular layer 5' 
of the porous van der Waals-type material, the annular wall portion of the 
separator member containing radially-extending through bores 17. The lower 
portion of the separator member and the drive motor 6' are submerged 
within a liquid condensate bath 14'. A portion of the liquid condensate 
14' is transmitted by pump 9 to the refrigeration type heat exchanger 10 
which provides the desired cooling of the liquid condensate. Another 
portion of the liquid condensate is supplied via restrictor 11 to the heat 
exchanger 12, which heat exchanger converts the condensate liquid to the 
vaporous of gaseous state for reintroduction into the low pressure chamber 
7'. In the illustrated embodiment, water is selected as the medium under 
consideration. 
OPERATION 
In this practical example, one must first evacuate container 3' as well as 
the associated pipelines and secondary units, before there is any filling 
with water. After that, separator 4' is rotatably driven via motor 6', and 
the circulating pump 9 as well as the series-connected heat exchanger 10 
are placed in operation. After separator 4' and the annular layer 5' have 
reached the desired rpm, any liquid that is possibly present is 
transported radially via the molecular body of layer 5', out of the inside 
of separator 4', followed by the water vapor that is bound and liquefied 
by van der Waals forces. A pressure difference is built up between 
low-pressure chamber 7' or the inside of separator 4, on the one hand, and 
high-pressure chamber 8, on the other hand. Radially arranged openings 17' 
are provided in separator 4' to facilitate the exit of the condensate, 
released from layer 5' into the high-pressure chamber 8'. 
Circulating pump 9 constantly circulates a portion of the developing 
condensate quantity and this is again supplied via heat exchanger 10 to 
high-pressure chamber 8'. As a result, separator 4', or the other parts 
that are heating up, are cooled down, that is to say, the generated waste 
and condensation heat is evacuated. A part of the liquid stream, conducted 
through the heat exchanger 10, is branched off and is supplied, via a 
throttle 11, arranged in front of utility heat exchanger 12, to the 
latter. The heat supply to utility heat exchanger 12 results in constant 
evaporation and thus influx of steam/gas molecules to low-pressure chamber 
7'. The developing liquid molecules are moved, via suction pipe 2, to the 
interior of annular layer 5 and there they are absorbed in certain 
proportions as described. Depending on the operating conditions, the 
feeder stream is charged with a gas part between high-pressure chamber 8' 
and heat exchanger 10 to a certain extent. 
After heat evacuation in heat exchanger 10, all gas parts are condensed so 
that there is only liquid in the pipeline. 
Because only minor pressure differences result between high-pressure 
chamber 8' and low-pressure chamber 7' in the practical example shown in 
FIG. 5, requirements are made only for the sealing between gland 1 and 
partition 24, whereby the provision of expensive design measures is 
avoided. 
Besides, a possibly minor leakage in the area of the seal signifies merely 
an impairment of the efficiency but not an impairment of the operation as 
such. 
In contrast to a condensation according to the displacement principle -- 
where a gas or steam volume is sucked in and is condensed with alternating 
polytropic exponent to liquefaction pressure -- looking at the process 
according to the invention, assuming a certain efficiency, only the 
gas/steam molecules, that move at high speed in low-pressure chamber 7', 
are trapped by means of van der Waals forces. 
Influx of the steam/gas molecules to the inside annular surface of rotating 
layer 5 is comparable to the influence of gas/steam molecules in a jet 
apparatus. Because of the relatively high speed of the steam molecules (in 
case of water vapor in the range of +4.degree. C. slightly overheated, the 
average speed is more than 600 m/sec), the suction cross section present 
over the separator 4 is dimensioned more than adequate to make sure that 
the molecules to be adsorbed will constantly continue to flow. 
The precise surface, the type of drying agent or molecular sieve, as well 
as the rpm geometry of the rotating layer 5 will depend on the substance 
to be condensed and can be determined in advance theoretically although 
they can also be determined empirically regarding the ratio between 
impacting and adsorbed steam/gas molecules per unit of time. 
The thickness of layer 5 must be so dimensioned that one can prevent 
after-evaporation of the already liquefied steam/gas from the outside in 
the direction toward the inside of the rotating layer 5. At the same time, 
the thickness of layer 5 must be sufficient to ensure heat evacuation to 
the outside. The latter can be improved, for example, by using an alloy or 
sintering between the driving agent/molecular sieve material and a 
neutral, well heat-conducting substance, such as, for example, aluminum. 
The output to be indicated is determined by the steam/gas molecules that 
are accelerated to circumferential speed, the liquid friction losses on 
the outside or rotation cylinder 4, the power consumption of the secondary 
units, as well as the efficiency of motor 6 with possibly connected 
frequency transformer. 
The process, which was explained by way of example with the help of water 
vapor, can of course also be used for other industrial gases as well as 
higher-molecular substances. Other suitable vaporous or gaseous media 
include Benzol, nitrogen, oxygen, or hydrogen. The cooling fluid of 
chamber 18 of the embodiment of FIG. 2 may be a suitable non-volatile 
fluid, such as oil. The rotational velocity of the separator cylinder is 
such as to give the desired centrifugal force to the liquid molecules to 
be discharged. The centrifugal force should be in the range of 5.000 g 
(where g=9.81 m/sec.sup.2). The centrifugal force for example, is produced 
by a separator cylinder having a diameter of about 400 mm and a rotational 
speed of about 6000 min.sup.-1.