U.S. patent application number 09/874264 was filed with the patent office on 2001-10-11 for clothes washer and dryer system for recycling and reusing graywater.
This patent application is currently assigned to Mainstream Engineering Corporation. Invention is credited to Back, Dwight D., Cole, Gregory S., Scaringe, Robert P..
Application Number | 20010027580 09/874264 |
Document ID | / |
Family ID | 22566064 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010027580 |
Kind Code |
A1 |
Back, Dwight D. ; et
al. |
October 11, 2001 |
Clothes washer and dryer system for recycling and reusing
graywater
Abstract
A compact, portable clothes washer and dryer system requires no
direct water connection or drain line and includes a feed reservoir
for holding hot or cold water; a basket for receiving clothes and
said water from said feed reservoir; a filtration membrane unit
that generates permeate for rinsing said clothes and retentate; a
motor for operating said basket; a pump for circulating water from
said feed reservoir through said membrane unit and to said basket;
and a heating assembly for drying said clothes in said basket. The
system reduces water usage and gray water generation for washing
clothes. The system is particularly useful in dormitories, small
apartments, or other remote dwellings where water is scarce or
where there are no water feed lines or drains.
Inventors: |
Back, Dwight D.; (Melbourne,
FL) ; Scaringe, Robert P.; (Rockledge, FL) ;
Cole, Gregory S.; (Ormond Beach, FL) |
Correspondence
Address: |
CROWELL & MORING, L.L.P.
P.O. Box 14300
Washington
DC
20044-4300
US
|
Assignee: |
Mainstream Engineering
Corporation
|
Family ID: |
22566064 |
Appl. No.: |
09/874264 |
Filed: |
June 6, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09874264 |
Jun 6, 2001 |
|
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09157956 |
Sep 22, 1998 |
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6269667 |
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Current U.S.
Class: |
8/158 ; 68/18F;
68/20 |
Current CPC
Class: |
D06F 39/00 20130101;
Y10S 68/902 20130101 |
Class at
Publication: |
8/158 ;
68/18.00F; 68/20 |
International
Class: |
D06F 023/02; D06F
039/10 |
Claims
What is claimed is:
1. An integrated washer and dryer system, comprising: a feed
reservoir for holding hot or cold water; a basket for receiving
clothes; a motor for operating said basket; a filtration membrane
unit that generates permeate for rinsing said clothes; a pump for
circulating said water from said feed reservoir to said basket; and
a heating assembly for drying said clothes in said basket.
2. The washer and dryer system according to claim 1, wherein said
pump is arranged to circulate the water from said feed reservoir
through said membrane filtration unit to backflush a filter element
in said membrane filtration unit and then to said basket.
3. The washer and dryer system according to claim 1, wherein said
motor is a variable-speed motor.
4. The washer and dryer system according to claim 3, wherein said
motor is at least a two-speed motor.
5. The washer and dryer system according to claim 1, wherein said
heating assembly comprises a heating element.
6. The washer and dryer system according to claim 5, wherein said
heating element is a resistance heater.
7. The washer and dryer system according to claim 5, wherein said
heating assembly further comprises a fan or blower.
8. The washer and dryer system according to claim 1, wherein said
basket has a diameter of about 6 to 24 inches.
9. The washer and dryer system according to claim 1, wherein said
basket is made of stainless steel.
10. The washer and dryer system according to claim 1, wherein said
feed basket holds about 1 to 5 gallons of water.
11. The washer and dryer system according to claim 1, wherein said
system is closed loop and has no direct water feed lines or
drains.
12. The washer and dryer system according to claim 1, wherein said
unit is front-loaded.
13. The washer and dryer system according to claim 1, wherein said
filtration membrane unit comprises an ultrafiltration or
microfiltration membrane.
14. A process for washing and drying clothes in an integrated unit,
comprising: placing clothes in a basket; adding hot or cold water
to a feed reservoir: pumping said water from said feed reservoir
into said basket; washing said clothes in said basket, thereby
generating graywater; directing said graywater to said feed
reservoir; pumping said graywater from said feed reservoir through
a membrane filtration unit, thereby generating permeate and
retentate; directing said retentate to said feed reservoir;
directing said permeate to said basket and rinsing said clothes
with said permeate, thereby generating additional graywater;
directing said additional graywater to said feed reservoir; and
drying said clothes in said basket.
15. The process according to claim 14, wherein the step of pumping
the water comprises pumping the water from said feed reservoir
through said membrane filtration unit to backflush a filter element
in said membrane filtration unit.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] Clothes washers generate a considerable quantity of gray
water during a normal wash/rinse cycle. Typically, 25 to 45 gallons
can be generated in a single load, which amounts to billions of
gallons of gray water a week when extrapolated out to 100,000,000
households and 2 or 3 loads of laundry a week. Not only is the gray
water generated and sent to the sewer or septic tank, but an equal
quantity of fresh water must be supplied to the washing machine.
This is a tremendous burden on water treatment facilities, public
water suppliers, and the environment.
[0002] Another critical issue in clothes washers and dryers is
energy costs. The vast majority of electricity costs for clothes
washers is in heating water. It is likely that in the near future
regulations will be placed on appliance manufacturers to minimznize
the energy usage of their products. Some steps have been taken, or
are currently being taken, by some appliance manufacturers
including a trend toward front loading, reduced water clothes
washers. These systems still, however, can use up to 10-25 gallons
of water per wash/rinse cycle.
[0003] Graywater reuse has been a technology area under rapid
development during the past 25 years. The treatment and recycle of
graywater (e.g., water from clothes washers carwashes, dishwashers,
and showers) has been explored and put into limited practice for
commercial and military applications. There is no consensus as to
the optimum process for all applications, since the treatment and
recycle scheme depends strongly on the size of the application,
chemical and physical properties of the graywater, and logistic
requirements of the operation.
[0004] Currently, most graywater recycle applications have been
targeted for carwashes and commercial coin laundries, utilizing
depth filtration and carbon adsorption. For example, systems have
been demonstrated which use sand filters, centrifugal separators,
precipitation of surfactants and other organics, and adsorption
media. Other graywater reuse strategies such as chemical
precipitation and distillation require several chemicals to be
inventoried for treatment, and the processes in general are very
sensitive to the chemical environment and temperature, sometimes
requiring specific detergent formulas. Distillation, evaporation,
or precipitation can produce fouling on the interior parts of
equipment if not prefiltered or controlled properly, creating a
maintenance nightmare. Distillation also consumes a considerable
amount of power.
[0005] Adsorption and ion exchange could also be use to remove
surfactants and organics, however, the inventors have found that
the capacity of adsorption media for graywater constituents is
limited, so these systems would be large. The water could also be
recycled by chemically destroying the surfactants and organics in
the graywater, but these processes can produce more toxic
by-products, require the handling of hazardous co-reactants such as
peroxides or ozone, and are generally energy intensive (e.g., ozone
generation or electron beam power).
[0006] In light of the Environmental Protection Agency's (EPA)
"zero discharge" mandates, domestic water conservation movements,
municipal graywater recycle ordinances, and EPA thrusts toward
low-water and reduced-detergent washers, graywater recycle
strategies are beginning to emerge in limited applications across
the country. The general trend of graywater recycling efforts is in
the direction of membrane separation, with supporting prefiltration
and post-polishing steps depending on the specific application.
Prior attempts to integrate membrane filtration with gray water and
other wash stream recycle have not succeeded in demonstrating an
immediate reuse process. Laundry recycle processes were attempted
in the 70's and 80's, however, many of these processes never
completed a pilot scale demonstration owing to membrane fouling
caused by improper/ill-defined prefiltration, the unavailability of
larger lumen hollow fiber membranes, or the use of reverse osmosis
(TO) which generally fouls easily and requires higher operating
pressures and power requirements compared to ultrafiltration (UF)
or microfiltration (MF).
[0007] Current gray water recycle/reuse strategies rely on storage
of the cleaned water for eventual reuse, or, clean-up of the water
to a quality which is unnecessary and essentially "overkill" for a
clothes washing process. The above-referenced copending patent
application Ser. No. 08/600,460 discloses a process using
ultrafiltration or microfiltration whereby gray water can be
immediately re-used for further clothes cleaning extraction without
storage of the permeate.
[0008] The present invention makes use of this improved process in
a unique system which washes clothes with no external water
connections or drains, and dries the clothes all in the same
portable self-contained unit. The operation of the unique system
provides a self-cleaning feature to extend the life of the
filtration element. No water heater is needed because the user
controls whether the load will be warm/hot or cold by filling feed
reservoir with warm/hot or cold water.
[0009] The present invention also targets smaller clothes washing
loads than conventional clothes washers which will benefit persons
in dormitories, small apartments, or other remote living quarters.
Without washer recycling, the water volume needed would have been
impractical in such situations to carry to and from the portable
unit.
[0010] One object of this invention is therefore to provide a
system which uses a minimal amount of water for washing
clothes.
[0011] Another object of this invention is to provide a
self-contained washer/dryer unit which does not require a drain
line or water connection or vent.
[0012] Yet another object of this invention is to provide an
apparatus to wash and dry clothes in a small apartment, dormitory,
or other remote location which does not have the convenience of
water connections and drain lines.
[0013] A still further object of this invention is to provide a
process and system utilizing a membrane filtration element which
will automatically backflush and clean the membrane at each use,
thus eliminating the need to periodically disassemble the system
and either replace or clean the filter.
[0014] Another object of this invention is to provide a washer and
dryer system which uses less water for the wash and rinse cycles
than washers not using a membrane recycle system.
[0015] Still another object of this invention is to provide a
washer/dryer system which reduces energy costs by using hot water
feed for the wash cycle and reusing the same hot or warm water for
the subsequent rinse, thus eliminating the need to heat the rinse
water.
[0016] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description when considered in conjunction with the accompanying
drawings herein.
BRIEF DESCRIPTION OF THE DRAWING
[0017] The sole Figure is an overall schematic diagram of one
embodiment of the present invention comprised of a combined
washer/dryer system.
DETAILED DESCRIPTION OF THE INVENTION
[0018] According to a presently preferred embodiment of the present
invention, and as depicted in the sole Figure, the washer/dryer
combination which includes a horizontal-axis, perforated washer
basket 1 containing baffles and located inside a larger drum 2; an
ultrafiltration or microfiltration membrane filtration element 3; a
feed reservoir 4; a washer basket spin motor 5 which can operate
the washer basket at at least two speeds, low and high, and the
motor can also spin the washer basket in both directions; a pump 6
for circulating water through the filtration element; a
prefiltration element 7 located after pump 6 in the illustrated
embodiments but other contemplated embodiments can locate this
element elsewhere in the system; control valves 8a, 8b, and 8c; a
heating assembly 9 comprising a heating element with optional fan
or blower; optional pump 10; and other plumbing and fittings which
may vary depending on the size and design specific of the system.
If pump 6 is connected to the spin motor then valve 8c is needed.
However, if a separate pump motor is used, valve 8c is not
necessary.
[0019] To carry out this invention, the wash cycle commences by
connecting a feed reservoir 4 of fresh water, hot or cold, to the
feed line 11 on the system. Because the system does not require a
heater for the wash water, a reduction in amperage demand for the
unit is achieved. The user will choose whether to select hot or
cold water for the wash and rinse by filling the feed reservoir 4
with either hot or cold water from an external water supply (e.g.,
sink) at the beginning of the wash cycle. The user would also add
an appropriate amount of detergent to the feed reservoir or washer
basket. After adding dirty clothes to the washer basket, the user
would then activate the washer by pressing an "on" button or the
like which turns on motor 5 at low speed. The same motor 5 which
rotates the washer basket could also be used to power pump 6. Pump
6, powered by the basket spin motor, a separate motor, or the like
feeds the water from the feed reservoir 4 through the permeate port
line 15 and out line 12 and/or line 14 of a membrane filtration
element 3 to backflush the filter element and fill the washer
basket. When the reservoir 4 is emptied, the water contained in the
feed reservoir has now been moved to the washer basket.
[0020] After emptying the feed reservoir 4, the washer basket
begins to spin, or tumble, at low speed to agitate the clothes
during washing. After a specified period of time, typically 5 to 20
minutes, the wash cycle is completed. The water contents of the
washer basket 1 are then transported back to the feed reservoir 4
through the line 13 by the pump 10 or allowed to drain by gravity
through the valve 8b.
[0021] The next step in the clothes washing cycle is the rinsing
step. Pump 6 is activated and the water in the feed reservoir is
flowed through valve 8a to the retentate feed port 16 (and
hollow-fiber lumen interior flow path) and out of the membrane
cartridge through line 14 back to the feed reservoir 4. The
permeate generated while flowing the water from the feed reservoir
through the membrane cartridge 3 is then directed through line 12
to the washer basket containing the clothes. A motor, either
separate from or the same as the motor powering the pump 6, will
also spin the washer basket on high at about 200 to 600 rpm as
programmed by the user or the manufacturer.
[0022] In one embodiment, the washer basket 1 remains stationary
for about 5 to 30 minutes while it accumulates water from the
membrane cartridge permeate through line 12. Then, after a preset
period of time, the washer basket 1 spins for another 5 to 30
minutes with permeate continuing to be sprayed onto the clothes. A
pump 10 can be used to flow the water from the outer drum 2 to the
feed reservoir 4, or, the washer basket 1 and outer drum 2 can be
situated to gravity drain the water in the outer drum 2 into the
feed reservoir 4 through a valve 8b. Either valve 8b or pump 10 is
needed, but not both. The process of rinsing can be carried out in
a variety of embodiments consisting of any number or combination of
static fills, agitation, or permeate sprays coupled with washer
basket spins.
[0023] To complete the rinse cycle, valve 8c is closed and/or pump
6 is deactivated and the clothes are spun in the washer basket for
an additional period of time to remove excess water. This extracted
water continues to drain to reservoir 4 through line 13.
[0024] Another embodiment of this invention would allow for
additional rinse cycles whereby the washer basket 1 is refilled
with permeate, agitated, spun, and sprayed with permeate. This
process could be repeated one or more times in addition to the
single wash and single rinse illustrated above.
[0025] After completing the wash and one or more rinse cycles, the
clothes are dried using heating element 9 located within the washer
cabinet. This heater dries the clothes by using the heating element
in forced or natural convection while tumbling at low speed using
motor 5. In the preferred embodiment, the heating element would be
a resistance heater. Clothes will contain up to about 0.4 lb water
or less per lb of dry clothes after the last rinse cycle, and
typically after a rinse spin cycle the amount of water remaining on
the clothes will be less. For example, assume 0.2 lb water per lb
clothes remains after a particular wash and rinse cycle. Therefore,
the heater must remove about 1 to 1.5 lbs of water to dry the 5 to
7 lbs of clothes in the washer basket. The heat of vaporization of
water is about 1000 STU/lb, so drying 5 to 7 lbs of clothes will
require about 1000 to 1500 BTU or 0.30 to 0.44 kW-hr. The heating
element in the washer is sized accordingly to affect drying within
a reasonable period of time. For example, to dry the clothes in 45
minutes, the minimum size for a resistance heating element is about
400 to 600 W. using a 120 VAC circuit means the current draw would
be about 5 amps or less which can easily be handles by a typical 15
to 20 amp circuit.
[0026] After the drying process is completed, the feed reservoir,
which contains the gray water generated during the wash and rinse
process can now be removed from the washer system and discarded.
The preferred embodiment of the system will include appropriate
check valves or other control devices to maintain water in the
filtration column 3 at the completion of the wash and rinse
cycle.
[0027] This invention has particular advantages for use in
dormitories, small apartments, or other remote locations which do
not have water connections (drain line, water supply) readily
available. It is also advantageous with respect to the dryer which
does not require any venting lines. In particular, a washer/dryer
device which can wash 5 to 7 lbs of clothes would be advantageous
because the size of such a unit would be very compact with an
approximate 6" to 24", preferably 10" to 12", diameter washer
basket. A unit having this size and dimension would also require
about 1 to 5 gallons, preferably about 1 to 2 gallons, of water in
addition to the water inventory in the filtration element and
plumbing. Since 1 to 2 gallons of water weigh about 8 to 16 lbs,
the water feed reservoir 4 is permitted to be lightweight and
easily managed by even elderly users.
[0028] Particular advantages flow from using a cross-flow
ultrafiltration element with hollow-fiber lumens and a molecular
weight cutoff (MWCO) in the range of 10,000 to 500,0000, the
optimum MWCO depending upon the specific construction and matrix of
the membrane material. Microfiltration elements having a pore size
of about 1 micrometer or less could also be used as the membrane
filtration element. The preferred material of
[0029] construction for the perforated washer basket is stainless
steel; however, other materials compatible with bleach, detergent,
and temperatures at or above room temperature can also serve the
function.
[0030] The preferred washer basket orientation would be horizontal,
in light of the advantages with regard to water requirements. The
washer system would therefore contain a front loading door through
which the clothes would be loaded. This door or opening can consist
of a hinged, latched door, or a screw-on, or bayonet type lid.
[0031] The membrane element of this invention is best maintained by
periodically cleaning the system with a dilute bleach solution.
This is particularly true for cases where the user does not expect
to use the washer for a period of about 1 week or longer. Hence,
running an empty wash/rinse cycle with a dilute solution of bleach
would be in best practice to clean and also store the system.
[0032] The net result of this washer/dryer system is a major
reduction in water usage and power consumption. The combination
washer/dryer is also a non-venting system so that the water
vaporized from the clothes in the dryer can be condensed into the
cooler feed reservoir 4 or vented to the room.
[0033] In addition to the energy savings, this invention will
greatly reduce the burden on water treatment facilities and waste
disposal (i.e., energy and resources devoted to water treatment).
The water utilization by communities or local groups using these
systems will also be greatly diminished since much less water will
be required to wash the same weight of clothes. All of these
benefits indirectly decrease the energy costs for a community's
water treatment facility since LESS water must ultimately be
treated and supplied, decreasing the demand on water processing
equipment. There will also be energy savings related to lower
volumes of water treatment and surfactant (detergent) use. The cost
in water usage and disposal incurred by the user will also be
reduced.
[0034] The foregoing disclosure has been set forth merely to
illustrate the invention and is not intended to be limiting. Since
modifications of the disclosed embodiments incorporating the spirit
and substance of the invention may occur to persons skilled in the
art, the invention should be construed to include everything within
the scope of the appended claims and equivalents thereof.
* * * * *