Abstrict A gas drying device (30) in which wet gas (31) is introduced into
a chamber (36) containing desiccant (38) in which the desiccant
(38) adsorbs moisture from the wet gas (31) to dry the wet gas (31)
and in which energy is utilized to energize and to remove the moisture
from the desiccant (38) to dry and to regenerate the desiccant (38)
for reuse to dry wet gas (31) includes a microwave generator (52)
and an antenna member (48) in communication with microwaves (50)
generated by the microwave generator (52) in which at least a portion
of the antenna (48) is disposed within the chamber (46). Also included
is a method for drying wet gas (31) in which wet gas (31) is introduced
into a chamber (46) containing desiccant (38) in which the desiccant
(38) adsorbs moisture from the wet gas (31) in drying the wet gas
(31) and microwave energy is applied to the adsorbed moisture to
remove the moisture from the desiccant (38) to regenerate the desiccant
(38) for reuse in drying wet gas (31) which includes the steps of
placing an antenna member (48) into communication with microwaves
(50) generated by a microwave generator (52) and disposing at least
a portion of the antenna member (48) into the chamber (46) containing
the desiccant (38).
Claims I claim:
1. A method for drying wet gas in which wet gas is introduced into
a chamber having an interior wall with a bottom interior wall portion
defining a bottom chamber portion and a top interior wall portion
defining a top chamber portion in which the bottom chamber portion
contains desiccant, whereby the desiccant adsorbs moisture from
the wet gas in drying the wet gas and subsequently microwave energy
is introduced into the chamber and purge gas is introduced into
the bottom chamber portion to remove moisture from the desiccant
and to regenerate the desiccant for reuse in drying wet gas, comprising
the steps of:
placing an antenna member having a top antenna end and a bottom
antenna end into communication with microwaves generated by a microwave
generator; and
disposing the bottom antenna end into the chamber and into the
desiccant contained in said chamber and in which the bottom antenna
end is spaced apart from the bottom interior wall portion of the
chamber defining the bottom chamber portion and containing the desiccant
from which the purge gas is introduced.
2. The method of drying wet gas of claim 1 includes the step of
orienting a waveguide relative to the microwave generator for receiving
microwaves from the microwave generator.
3. The method of drying wet gas of claim 1 includes the step of
disposing a portion of the antenna member within the waveguide.
4. The method of drying wet gas of claim 3 in which the step of
disposing a portion of the antenna within the waveguide includes
the step of enclosing substantially the entire the portion of the
antenna member within the waveguide.
5. The method of drying wet gas of claim 1 includes the step of
diposing at least one other antenna member in the chamber and spaced
from the antenna member.
6. The method of drying wet gas of claim 5 includes the step of
placing at least two other antenna members in the chamber and spaced
substantially equal distance from the antenna member.
7. The method of drying wet gas of claim 5 includes the step of
placing at least one other antenna member substantially parallel
to the antenna member.
8. The method of drying wet gas of claim 5 in which the step of
disposing at least one other antenna member in the chamber includes
the step of disposing the at least one other antenna member completely
within the chamber.
9. The method of drying wet gas of claim 5 includes the step of
disposing at least a portion of the at least one other antenna members
into the desiccant.
10. The method of drying wet gas of claim 5 includes the step of
disposing at least three other antenna members within the chamber
in which two of the at least three other antenna members are spaced
substantially equal distance to a third other antenna member of
the at least three other antenna members.
11. The method of drying wet gas of claim 10 in which the at least
the three other antenna members within the chamber are spaced from
the antenna member and each other and are oriented substantially
parallel to the antenna member and each other.
12. The method of drying wet gas of claim 1 includes the step of
introducing a purge gas into the chamber through an inlet in the
chamber to move moisture released from the desiccant out of the
chamber through an outlet in the chamber.
13. In a gas drying device in which wet gas is introduced into
a chamber having an interior wall with a bottom interior wall portion
defining a bottom chamber portion and a top interior wall portion
defining a top chamber portion in which only the bottom chamber
portion contains desiccant, whereby the desiccant adsorbs moisture
from the wet gas to dry the wet gas and in which purge gas is subsequently
introduced into the bottom chamber portion to remove the adsorbed
moisture from the desiccant to regenerate the desiccant for reuse
to dry wet gas, the improvement comprises:
a microwave generator; and
an antenna member having a top antenna end and a bottom antenna
end and in which the antenna member is in communication with microwaves
generated by the microwave generator with the bottom antenna end
disposed within the chamber and in communication with the desiccant
located therein and in which the bottom antenna end is spaced apart
from the bottom interior wall portion of the chamber defining the
bottom chamber portion and containing said desiccant from which
the purge gas is introduced.
14. The gas drying device of claim 13 which includes a waveguide
oriented with respect to the microwave generator to receive microwaves
generated by the microwave generator.
15. The gas drying device of claim 14 in which a portion of the
antenna member is disposed within the waveguide.
16. The gas drying device of claim 14 in which the waveguide is
disposed outside of the chamber.
17. The gas drying chamber of claim 16 in which a portion of the
antenna member is disposed outside of the chamber has at least a
part of the portion disposed within the waveguide.
18. The gas drying device of claim 14 in which the waveguide is
connected to the chamber and substantially encloses a portion of
the antenna member which is disposed outside of the chamber.
19. The gas drying device of claim 13 in which the antenna member
is secured to the chamber at an opening in said chamber.
20. The gas drying device of claim 19 in which an insulative material
is disposed between the antenna member and a wall of the chamber
at said opening.
21. The gas drying device of claim 20 in which the insulative material
is TEFLON.
22. The gas drying device of claim 20 in which the insulative material
is in the form of a bushing which engages the antenna member and
the wall of the chamber at said opening.
23. The gas drying device of claim 13 in which the antenna member
is composed of aluminum.
24. The gas drying device of claim 13 in which the antenna member
is in the shape of a rod.
25. The gas drying device of claim 13 in which the antenna member
is solid.
26. The gas drying device of claim 13 in which the antenna member
has an outside surface which is substantially smooth.
27. The gas drying device of claim 13 in which the chamber is elongated.
28. The gas drying device of claim 13 in which the chamber has
a length and the antenna member is disposed substantially along
the length of the chamber.
29. The gas drying chamber of claim 13 in which the chamber has
a cross section in which the antenna member passes through a central
portion of the cross section of the chamber.
30. The gas drying device of claim 13 in which said chamber has
at least a portion which is substantially cylindrical and a corresponding
cross section which is substantially circular.
31. The gas drying device of claim 19 in which the antenna member
extends substantially along the length of the cylindrical shape
and through the central portion of the corresponding circular cross
section.
32. The gas drying device of claim 30 in which the at least one
other antenna member is oriented substantially parallel to the antenna
member within the chamber.
33. The gas drying device of claim 13 in which at least one other
antenna member is disposed within the chamber.
34. The gas drying device of claim 33 in which the at least one
other antenna member is entirely disposed within the chamber.
35. The gas drying device of claim 33 in which the at least one
other antenna member is spaced apart from the antenna member within
the chamber.
36. The gas drying device of claim 33 in which the at least one
other antenna member includes at least two other antenna members
in which the at least two of the other antenna members are substantially
equally spaced from the antenna member.
37. The gas drying device of claim 33 in which the at least one
other antenna member includes at least two other antenna members
in which the at least two of the other antenna members are substantially
parallel to each other and the antenna member and spaced apart from
each other.
38. The gas drying device of claim 33 in which the at least one
other antenna member includes at least three other antenna members
in which the at least three other antenna members are spaced from
the antenna member and from each other and in which two of the three
other antenna members are substantially equally spaced from a third
other antenna member.
39. The gas drying device of claim 13 in which the chamber has
an outlet and an inlet in which a purge gas is introduced into the
chamber through the inlet to move moisture released from the desiccant
out of the chamber through the outlet.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of gas or air drying
devices and more particularly to regenerative gas or air drying
devices which utilize desiccant to dry air or other gases in a chamber
in one portion of the device in which wet air or gas is passed through
the desiccant contained in such chamber and the moisture is adsorbed
by the desiccant and in another portion of the device microwaves
are dispersed through another chamber containing saturated desiccant,
which had become saturated in previously drying wet air or gas,
to increase the temperature of the moisture that was adsorbed by
the desiccant to enhance the drying of the desiccant for reuse to
again dry wet air or gas.
2. Description of the Related Art Including Information Disclosed
Under 37 CFR .sctn..sctn.1.97-1.99
Drying devices receiving a gas under pressure such as air containing
a high level of moisture are well known. These gas drying devices
are commonly used in many industrial applications such as painting,
pneumatic control systems and air operated equipment. It is also
known in such devices to utilize a desiccant such as activated alumina,
carbons, silica gels or molecular sieves located in a chamber to
adsorb and remove the moisture from the inlet wet air or gas that
is under pressure. Such air drying devices frequently use a portion
of the dried air or purge gas from one desiccant chamber that is
drying air to regenerate the desiccant in another chamber that has
already removed moisture from the wet air in a previous cycle. The
portion of dried air or purge gas is often diverted to a heater
to elevate the temperature of the purge gas. Thereafter, the heated
purge gas is moved to the other desiccant chamber to dry out and
regenerate the saturated desiccant located therein.
Referring to FIG. 1 a known regenerative gas drying device is
shown receiving wet gas (shown as solid arrows) through inlet 10.
The wet gas enters a chamber 12 through screen 13 which is filled
with desiccant 14. As the wet gas migrates through chamber 12 moisture
in the gas is adsorbed by desiccant 14 thereby drying the gas. The
dried gas (shown as hollow arrows) exits chamber 12 through screen
15 and is carried to gas outlet 16 at which, the dried gas leaves
the drying device. However, not all of the dried gas exits the device
for use. A small portion of the gas or commonly called purge gas
is diverted into transport pipe 18 and is carried to heater 20.
The purge gas is heated at heater 20 and subsequently, is transported
to another chamber 22 and enters chamber 22 through screen 23. Chamber
22 is filled with desiccant as in the first chamber 12 however,
desiccant 14 in chamber 22 is saturated with moisture from a previous
air drying cycle. The heated purge gas dries saturated desiccant
14 in chamber 22. The high moisture air from the drying of desiccant
14 in chamber 22 is removed from chamber 22 through screen 25 and
exits the air drying device at exit valve 24.
Once desiccant 14 in chamber 12 is saturated from an air drying
cycle and desiccant 14 in chamber 22 is dried out, the cycle is
reversed by flipping diverter valves 25A and 25B. The wet gas is
dried and heated upon passing through chamber 22 and heater 20.
The dry and heated purge gas from chamber 22 is, in turn, used to
dry the saturated desiccant of the first chamber 12. These known
systems normally utilized approximately 7 percent of total dried
air for the purge gas to regenerate desiccant. The regenerative
gas drying device is cycled in this manner to continuously dry out
the wet gasses.
Many problems arise in using these known systems. A large percentage
of the dried air is utilized for purge which is needed to regenerate
the desiccant. In addition, the purge is heated by heaters which
utilize large quantities of energy and operate at very high temperatures.
The high temperatures can precipitate further fire hazards particularly
when such heaters are in close proximity to oil lubricated compressors
used in conjunction with these systems to pressurize the desiccant
chambers.
It is also known in gas drying systems to send microwave energy
into pressurized tanks to heat gases adsorbed by desiccant materials
located therein. In U.S. Pat. No. 4312640 to Verrando issued Jan.
26 1982 and U.S. Pat. No. 4312641 to Verrando et al. issued
Jan. 26 1982 microwave energy is passed through microwave pressure
windows and into tanks carrying sorbent or desiccant material. The
microwaves are used to release and remove a polar gas adsorbed by
sorbent or desiccant material in the tanks. The microwave energy
is prevented from being sent into the tanks in response to the desorbtion
of the moisture from the sorbent material. Purge gas is still moved
through the desorbed desiccant until the moisture level of the chamber
is adequately lowered.
In U.S. Pat. No. 4322394 to Mezey et al. issued Mar. 30 1982
microwave energy is used to dielectrically heat saturated solids
of noncarbon adsorbents for the removal of adsorbed materials. The
microwaves heat the adsorbents internally to bring the adsorbents
to a temperature for desorbing some of the adsorbate in the absence
of any activating or purge gas.
Disadvantageously, in these known systems the distribution of the
microwave energy within the pressurized tanks is limited. The microwave
energy sent through pressure windows adjacent the tank enhances
the ability of removal of the adsorbed material proximate to the
pressure windows. However, since these known air drying systems
do not provide a means for dispersing the microwaves throughout
the tank, the material adsorbed by the desiccant located away from
the pressure windows does not get sufficiently energized by the
microwave to efficently desorb the adsorbate material. Thus, efficient
desorbtion of wet gas is achieved more effectively at locations
proximate to the pressurized windows while desiccant further away
from the pressure windows does not receive as effective and beneficial
microwave energy for desorbtion.
SUMMARY OF THE INVENTION
Accordingly, it is the principal object of the present invention
to provide a desiccant regenerating device which utilizes microwave
energy by effectively introducing and distributing the microwave
energy within the desiccant chamber and to the moisture adsorbed
by the desiccant.
Another object of this invention is to provide a microwave generator
and an antenna member in communication with microwaves generated
by the microwave generator in which a least a portion of the antenna
is disposed within the chamber for holding desiccant.
Another object of this invention is to provide a method for drying
wet gas which is dried by introducing the same into a chamber containing
desiccant which adsorbs moisture from the wet gas and to subsequently
dry or regenerate the desiccant by applying microwave energy to
the adsorbed moisture of the desiccant to remove the same from the
desiccant in order to regenerate the desiccant for reuse in drying
wet gas by placing an antenna member into communication with microwaves
generated by a microwave generator and disposing at least a portion
of the antenna member into the chamber for holding the desiccant.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing advantages, features and objects of the invention
will be described in more detail and others will be made apparent
from the detailed description of the preferred embodiments given
below with reference to the several views of the drawing, in which:
FIG. 1 is a schematic view of the gas drying device of the prior
art;
FIG. 2 is a schematic view of the gas drying device of the present
invention;
FIG. 3A is a partial schematic view of the top portion of the desiccant
chamber including a portion of the waveguide;
FIG. 3B is a top view of FIG. 3A;
FIG. 4A is a cross section view of the outlet of the desiccant
chamber designated as "O" in FIG. 3B;
FIG. 4B is a cross section along A--A of FIG. 4A;
FIG. 5A is a partial schematic view of another embodiment of the
gas drying device, as seen in FIG. 2;
FIG. 5B is a cross section view along line 5B--5B of FIG. 5A;
FIG. 5C is a cross section view of another embodiment along 5B--5B
of FIG. 5A;
FIG. 6 is a table and graphic representation of the table for the
performance of the gas drying device in which one antenna member
is used, as seen in FIG. 2; and
FIG. 7 is a table and graphic representation of the table for the
performance of the gas drying device of the embodiment shown in
FIG. 5A.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 2 gas drying device 30 is shown in which wet
gas 31 (illustrated by solid arrows) enters through wet gas inlet
32 and is introduced through channel 34 and screen 35 into gas drying
chamber 36 containing desiccant material 38. The desiccant 38 contained
in chamber 36 adsorbs moisture from the wet gas 31 in order to dry
the wet gas. Dried gas 40 (illustrated by hollow arrows) exits the
chamber 36 through screen 42 and is carried to dry gas outlet 44
at which dry gas 40 leaves the gas drying device 30. These gas drying
devices 30 are commonly used to dry wet air, however, other gases
can be similarly or analogously treated with use of these types
of devices. In addition, the chambers that hold the desiccant often
have gas under pressure introduced into the chamber in either the
adsorption procedure and the regeneration procedure or both, however,
the present invention would also be contemplated to work not only
with chambers utilizing gas under pressure but also in ambient or
nonpressurized environments.
As the one drying chamber 36 dries out wet gas 31 another chamber
46 of drying device 30 removes moisture adsorbed by desiccant 38
contained in the other chamber 46. Desiccant 38 of other chamber
46 was saturated with moisture when wet air was previously passed
through other chamber 46 in an earlier gas drying cycle.
Disposed within both gas drying chambers 36 and 46 is an antenna
member 48 which is in communication with microwaves 50 which are
generated by microwave generator 52. Waveguide 54 is oriented with
respect to microwave generator 52 to receive the microwaves so generated
from generator 52 and carry them to a portion of the antenna member
48A disposed within the waveguide. The microwaves are carried along
the length of the antenna 48 which has a portion 48A extending outside
of the chamber 46 and disposed within waveguide 54. Antenna 48 extends
through chamber 46 having portion 48B mounted or disposed outside
of desiccant 38 and another portion 48C within the chamber immersed
within the desiccant. The microwave energy is conducted by antenna
48 and travel along its length into the chamber 46 carrying the
desiccant 38. The microwave energy carried into chamber 46 is adsorbed
by the moisture held by the desiccant 38 which substantially reduces
the time needed to remove the moisture adsorbed by the desiccant
38 within the chamber. Thus in the interest of maintaining a relative
continuous dry air flow through dry gas outlet 44 one chamber 36
is drying wet gas 31 while the other chamber 46 is in the process
of drying and regenerating desiccant 38 and vice versa.
Preferably the antenna 48 is a solid, rod shaped, elongated aluminum
member. The aluminum antenna rod 48 has an outside surface which
is substantially smooth to prevent arcing of the high frequency
microwaves which are conducted by the aluminum antenna rod. However,
it is contemplated that other shapes and configurations of antenna
members may be used, as well as, various commonly known materials
may be used in constructing the antenna member of the present invention.
As seen in FIGS. 2 3B, 5B and 5C the shape of the chambers 3646
are substantially cylindrical in shape with the antenna member 48
disposed substantially along the length of the cylindrical chambers.
Extending antenna rod 48 substantially throughout the length of
the chamber 48 enables the microwave energy so carried by the antenna
to be dispersed substantially throughout the length of the chamber.
The elongate antenna member 48 preferably is disposed and passes
through a central portion of the chamber 46. The central positioning
of the antenna member 48 ensures that the microwave energy so carried
by the antenna rod is evenly distributed through the chamber body
46. Thus, the high frequency microwave energy is able to efficiently
remove the moisture adsorbed by the desiccant 38 in the chamber
during the desiccant drying regeneration cycle in the gas drying
device 30.
Referring still to FIG. 2 as the dried gas 40 exits the gas drying
chamber 36 a small percentage of the dry gas or purge gas 41 is
diverted into a transport pipe 56 with the vast majority of the
dry gas being removed from the device 30 through the dry gas outlet
44 for many various uses. This small diverted portion of the dried
gas or purge gas 41 enters into inlet 58 and through screen 60 and
into chamber 46 containing saturated desiccant 38. Moisture in saturated
desiccant 38 is desorbed from desiccant 38 by dispersed microwave
energy from antenna 48 by the adsorbed moisture in the desiccant
absorbing the microwave energy and elevating the energy level of
the moisture until the moisture releases from the desiccant. The
dry purge gas 41 moving through the chamber 46 absorbs the released
moisture and moves the moisture from the desiccant 38 and carries
the absorbed moisture out of the chamber 46 through screen 62 and
outlet 64. The present invention has dramatically dropped the amount
of purge gas 41 needed to remove the desorbed moisture from desiccant
chamber 46. In some demonstrations of use of the invention set forth
below only 2 per cent of the exiting dry gas 40 was utilized for
purge gas 41. Thus, a larger volume of dry gas 40 is available for
use rather than for purge and further there is no need for the purge
to be preheated prior to introduction into chamber 46 where the
moisture in the desiccant is being heated by microwave energy.
Advantageously, the insertion of the antenna rod member 48 within
the regenerating chamber 46 operating in conjunction with the microwave
generator 52 and waveguide 54 provides for the use of a much smaller
percentage of purge gas for drying and regenerating the moisture
adsorbing desiccant than was required in known gas dry devices.
Furthermore, the problems associated with known gas drying devices
employing expensive, bulk and hazardous heating systems are avoided
in the present invention.
Referring now to FIG. 3A, the top of the gas drying device 30 is
shown with the waveguide 54 disposed outside of the cylindrical
desiccant chamber 46. The antenna rod 48 is centrally positioned
within the chamber 46 and having a top portion 48A of the antenna
extending outside of the chamber in the waveguide 54 area. The microwave
energy generated by the microwave generator 52 FIG. 2 communicates
with the top portion 48A of the antenna member 48 in which top portion
48A is disposed within waveguide 54. The microwave energy which
communicates with top antenna portion 48A is carried along the length
of the antenna and is dispersed throughout the desiccant chamber
46. Waveguide 54 is connected to the chamber 46 at the top support
member 66 of chamber 46. Antenna member 48 is supported through
opening "O" at the top support member 66 of chamber 46.
Top portion 48A of the antenna member 48 is enclosed by the waveguide
54 in order for the antenna to intercept microwave energy 50 transmitted
within the waveguide 54. It is desirable that the waveguide 54 and
chamber 46 are arranged, as seen in FIG. 3A, such that the microwaves
within waveguide 54 do not leak out of the waveguide and thereby
create a health hazard.
Referring to FIG. 3B, the desiccant chamber 46 is shown from a
top view as having a circular configuration along the width of the
chamber which would provide a cross section of chamber 46 as substantially
circular. Chamber 46 with this configuration is substantially cylindrical.
The top portion 48A of the antenna member is positioned in alignment
with a central location or approximately along the longitudinal
axis of the cylindrical portion of the desiccant chamber 46. The
top support member 66 stabilizes and maintains the antenna member
48 in the chamber 46 with top portion 48A extending into the waveguide
54 path. The microwaves transmitted throughout the waveguide are
coupled with the top portion 48A of the antenna member for distribution
in the desiccant chamber 46.
Referring now to FIG. 4A, the top portion of elongate antenna rod
48 is secured within an opening "O" of the top support
member 66 of the desiccant chamber 46. An insulative material 68
is disposed between the antenna member 48 and an inner wall 70 at
the opening of the top support member 66 of the chamber 46. The
insulative material 68 held within the inner wall 70 of the top
support member 66 acts as an O-ring by engaging and supporting the
antenna member 48 at the opening of the chamber 46. Preferably,
the insulative material 68 is a TEFLON material to employ a tight
and secure hold of the antenna rod 48 and to reduce the occurence
of arcing with the chamber from the microwave energy. TEFLON is
a trademark name for the chemical composition of polytetrafluoroethylene.
Other well known excellent insulative materials that are substantially
transparent to microwaves as Teflon can be used.
Referring to FIG. 4B, the cross sectional view of FIG. 4A illustrates
the elongate antenna rod 48 supportably held by the O-ring or bushing
of the insulative material 68. The tight fit of the antenna member
48 with the insulative TEFLON material 68 in conjunction with the
secure positioning of the insulative material within the opening
at the inner walls 70 of the chamber 46 enables the antenna member
to be supported with the top portion 48A disposed within the waveguide
54 FIG. 3A and 3B, and the other portions 48B and 48C held within
the chamber 46. The tight fit also maintains the desired pressures
that can be introduced to chamber 46.
Referring now to FIG. 5A, an alternative embodiment of the present
invention shows the desiccant chamber 46 of the gas drying device
30 having three other antenna members 49 disposed within the chamber.
Each of the other antenna members 49 is entirely disposed within
the desiccant chamber 46. The other antenna members 49 are oriented
in a position substantially parallel to the length of the centrally
located antenna 48 and spaced from antenna 48 within the chamber
46. The other antennas 49 and the centrally located antenna 48 are
all spaced from one another sufficiently to avoid arcing. The granules
of the desiccant material 38 support the other elongate antenna
rods 49 within the chambers. Preferably the other antenna rods 49
are of a similar configuration to that of the centrally located
antenna rod 48. The other antenna members 49 are solid elongate,
aluminum rods having a smooth outer surface to reduce arcing of
the microwave energy so dispersed throughout the chamber 46. The
distribution of the other antenna members 49 within the chamber
46 provides for accelerated and even dispersement of microwave energy
throughout the chamber 46 thereby enabling increased efficiency
in the removal of moisture adsorbed by the desiccant 38.
Referring to FIG. 5B, the cross sectional view of FIG. 5A illustrates
the three other elongate antenna members 49 spaced apart from the
centrally located antenna member 48. Preferably, the other antenna
member 49 are equally spaced from the central antenna member 48
and each other to provide an even distribution of the microwave
energy within the chamber 46 and as mentioned above at distances
that will avoid arcing. The other antenna members 49 are preferably
positioned in a parallel relationship with each other and with the
length of the central antenna 48. The desiccant granules 38 as
mentioned above, support each of the other elongate antenna members
49 within the chamber 46.
Referring to FIG. 5C, a further alternative embodiment of the present
invention is shown in which six other antenna members 49 are equally
spaced from each other and from the centrally located antenna member
48. Again, each of the six other antenna members 49 are oriented
in a parallel relationship along their lengths with each other and
parallel along the length of the central antenna member 48 within
the chamber 46. The increase in the number of other antenna rods
49 within the chamber 46 coupled with the evenly spaced and parallel
positioning of the other rods provides for rapid temperature increase
throughout the chamber for quick and efficient removal of moisture
from the desiccant 38 during regeneration of desiccant cycles within
the chamber 46.
Referring now to FIGS. 6 and 7 these are charts and corresponding
graphs of those charts for tests on the embodiment of the invention
as shown in FIG. 2 and the embodiment of the invention as shown
in FIG. 5A respectively. The test for each embodiment utilized a
chamber holding approximately 50 pounds of activated alumina as
desiccant in which 7 pounds of water was introduced to the desiccant.
The microwave generator was 600 watts. The interior diameter of
the chamber was 8 inches. This drying device was comparable to an
80 cubic feet per minute unit which utilized only approximately
1.5 cubic feet per minute purge gas which equated to slightly less
than a 2 per cent demand for purge.
Thus, FIG. 6 is a test on the present invention where there was
only one centrally located antenna member 48 disposed in chamber
46. Antenna member 48 for this test was a 3/8 inch in diameter solid
aluminum rod. The microwave generator 52 was initiated with the
desiccant at approximately room temperature of 75 degrees Fahrenheit.
As time progressed, through a period of 5 minutes, temperature readings
were periodically taken in the dessicant at the top portion, middle
portion and bottom portion in chamber 46. Temperature readings were
also taken at these times of the discharge at outlet 64. The chart
and corresponding graph reflect the temperatures at the different
locations at specific times subsequent to the commencing of the
microwave generator.
The same test parameters were set for the test portrayed in FIG.
7 except in addition to the centrally located antenna member 48
there were three other antenna members 49 in the configuration shown
in FIGS. 5A and 5B. The three other antenna members 49 were suspended
in the desiccant and were also 3/8 inch in diameter solid aluminum
rods. As can be seen in comparing the values between FIGS. 6 and
7 there was a dramatic increase in the temperatures of each of
the locations of the top, middle, bottom and discharge locations
in the embodiment of FIG. 7. Thus, the rate of heating was faster
with the addition of the other antenna members 49 thereby accelerating
the release of the adsorbed moisture.
While the advantages of the invention are preferably obtained with
the gas drying device 30 described above with reference to FIGS.
2-7 the method of the invention can be practiced with any other
gas drying devices for drying wet gas introduced into a chamber
containing desiccant in which the desiccant adsorbs moisture from
the wet gas in drying the wet gas and microwave energy is applied
to the adsorbed moisture to remove moisture from the desiccant to
regenerate the desiccant for reuse in drying wet gas. The preferred
method of practicing the invention comprises the steps of (1) placing
an antenna member into communication with microwaves generated by
a microwave generator, and (2) disposing at least a portion of the
antenna member into a chamber containing desiccant.
Referring to FIG. 2 the method of drying wet gas 31 is done in
the gas drying device 30 by orienting a waveguide 54 relative to
the microwave generator 52 for receiving microwaves 50 from the
generator 52. A portion 48A of the antenna member 48 is disposed
within the waveguide 54. The method includes the step of enclosing
the entire portion 48A of the antenna members 48 within the waveguide
54. Another portion 48B of the antenna member 48 is disposed within
the chamber 46 with portion 48C inserted into the desiccant 38 contained
in the chamber 46.
Referring to FIGS. 5A-5C, the method of the present invention is
preferably performed by the step of disposing at least one other
antenna member 49 in the desiccant chamber 46 which is spaced away
from and parallel to the centrally located antenna member 48. Additionally,
the other antenna members 49 are completely disposed within the
chamber 46 and are held in position by the desiccant 38. The other
antenna members 49 are placed in the chamber with at least two of
the three other antenna members 49 being spaced at a distance substantially
equal to a third other antenna member 49. Each of the other antenna
members 49 are equally spaced and oriented parallel to each other
and the centrally positioned antenna member 48. The preferred positioning
is to place centrally located antenna member 48 and evenly space
other antenna members 49 from centrally located antenna member 48
and substantially parallel to the same. This general approach will
enhance distribution of the microwave energy. |