[0001] The present invention generally refers to the rinsing and drying of articles that
have been subjected to a washing process.
[0002] As it is known, a number of articles and workpieces are to be subjected to washing
(for removing residuals, oils, fats, etc.) in order to obtain a cleaned surface in
view of their intended use.
[0003] After the washing, such articles or workpieces are to be subjected to a neutralization
through one or more rinsings to eliminate the traces of detergents. Finally, to prevent
wet or damp areas from remaining on the surfaces of the rinsed articles, which could
start chemical attacks (such as oxidations), or leave stains or circles (due to deposits
of a hard water or to other reasons), the articles must be dried using particular
techniques.
[0004] At present the above final operations of rinsing and drying are carried out in the
atmospheric environment, that is in presence of the air components (oxygen, moist,
several vapors, etc.), as well as in presence of the dusts always present in the air.
[0005] In spite of using proper ruses and the utmost care, even with long treatment times,
a satisfactory result is not always ensured.
[0006] The object of the present invention is to obtain quickly and reliably dried articles
that have been submitted to washing and rinsing processes, having a surfaces stainless
and devoid of stains.
[0007] The above objects are achieved through a process as claimed in claim 1 and an apparatus
as claimed in claim 5.
[0008] For a better understanding of the invention, preferred but non limiting embodiments
of the apparatus and the process will be disclosed hereinbelow with reference to the
attached drawings, in which:
Fig. 1 is a schematic diagram illustrating the general construction of an apparatus
according to the invention; and
Fig. 2 is a schematic view of an alternate embodiment of the tank.
[0009] With reference to Fig. 1, an apparatus according to the invention comprises at least
a rinsing tank 1 adapted to contain the articles to be subjected to the washing and/or
rinsing and/or drying tratments, which is designed to withstand the stresses due to
pressures both higher and lower than the atmospheric pressure as well as to resist
to oxidative agents.
[0010] The tank 1 can be hermetically closed by means of a cover 2 that is manually or automatically
operated. Prefereably the apparatus comprises two of such tanks so that in one of
them a lot of articles can be rinsed while in the other another lot of articles is
being dried.
[0011] Through a valve 15 the tank 1 communicates with a vapor generator 3 having a capacity
adequate to the plant requirements. The heating source 30 of the vapor generator can
be one of the conventional sources, such as an electric heater, a heat exchanger,
a furnace burning a liquid, solid or gasous fuel, a heat pump, a sun-powered heater,
a gas compressor, etc.
[0012] To the tank 1 it is further connected a vapor cooling and condensing device 4. The
condenser 4 comprises a container housing a coil 21 and can be selectively communicated
with the tank 1 through a valve 17.
[0013] A pumping assembly 7 comprising a pump and two valves 13 and 14, is connected to
the bottom of the tank 1 through a valve 12. This pumping assembly is used for pumping
the rinsing liquid into the tank 1 and for its extraction. Valve 13 communicates the
assembly with a reservoir of rinsing liquid 19.
[0014] When the rinsing fluid is a pollutant or otherwise harmful, the apparatus is preferably
equipped with a storage tank 8 communicating with the tank 1 through a valve 11 and
a conduit length opening in the the upper portion of the tank sidewall.
[0015] The apparatus of the invention further comprises auxiliary components such as a cooling
device 5 and a pump-ejector assembly 6.
[0016] The cooling device 5 is of conventional design and comprises a cylinder-piston assembly
27, a refrigerating coil 28 and a fan 29 and communicates through a valve 21 with
the cooling and condensing device 4.
[0017] The pump-ejector assembly 6 includes an ejector 23, a pump 24 and a (second) condenser
25. The ejector 23 communicates with the cooling and condensing device 4, whereas
a valve 18 is interposed between the second condenser 25 and the cooling device 5.
[0018] The pump-ejector assembly 6 is used, when required, for extracting from the tank
1 the condensed fluids and possible gases that are not condensable when the tank is
under vacuum conditions. The assembly 6 is preferably provided for ensuring the expulsion
of air that might have passed through the seals.
[0019] Although not shown in the drawings, the apparatus of the invention comprises additional
automation devices such as valves, solenoid valves, automatic hydraulic cylinders,
etc. All the valves and the devices of the apparatus are controlled and operated by
a central control unit, preferably provided with a PLC or a programmed microprocessor.
[0020] When the apparatus of the invention is arranged in an automated washing plant, its
working is properly coordinated with the working of the main plant.
[0021] According to an alternate embodiment, as schematically shown in Fig. 2, a plate 22
is provided within the tank 1A, this plate being cooled by a coil 26 at programmed
times, thus acting as a condenser. Both the additional plate 22 and the main condenser
4 can be used for enhancing the drying stage. When using pollutant fluids, the cooling
is preferably carried out within the tank 1 in order to strongly reduce the level
of harmful vapors and to generate a gas trap for retaining the vapors within the tank
during the loading and unloading of the articles.
[0022] The process of the invention will now be illustrated with reference to the above
disclosed apparatus.
[0023] The operating cycle is started by introducing the articles into the empty tank 1
after removing or opening the cover 2. The articles can be positioned in the rinsing
tank 1 either manually or automatically and the tank contains supporting means or
devices (not shown) accomodating the shape and types of the articles to be rinsed.
[0024] After the articles have been properly arranged in the rinsing tank, the cover 2 is
tightly sealed and the tank is filled with a rinsing liquid (or a vapor) from the
pump assembly 7 and the valve 11 is opened so that the air is expelled from the tank
1 and forced into the air storage tank 8 (if present).
[0025] After the tank 1 has been filled with the rinsing liquid and all the air has been
expelled or transferred into the air storage tank 8, the valve 11 is closed.
[0026] After the tank 1 has been loaded as desired with the rinsing fluid, the articles
are subjected to a conventional rinsing cycle as desired or requested.
[0027] Then the rinsing liquid is slowly drained from the tank through the pump assembly
7 and returned to the reservoir 19. The drainage is slowly accomplished in such a
manner that the descending liquid surface "washes" the articles located in the tank
1.
[0028] During the progressive drainage of the rinsing liquid from the tank 1, valve 15 is
opened for admitting into the tank 1 a vapor under pressure from the generator 3,
the vapor occupying the vacant space left by the rinsing liquid being drained. The
temperature of the vapor from generator 3 is higher than that of the rinsing liquid,
and preferably the vapor is similar to the rinsing liquid. In all cases the vapor
is not of a type capable of reacting with the rinsing liquid or causing other negative
phoenomena.
[0029] This vapor flows through the portions of the articles emerging from the surface of
the liquid being drained and transfers thermal energy to the articles. Since the emerging
portions of the articles are initially at the same temperature of the rinsing liquid
(i.e. colder than the incoming vapor), the vapor condensates over the emerging portions
of the articles and the droplets run down the article surfaces with an additional
rinsing or microwashing of said surfaces.
[0030] This process takes place in a continuous manner on the surfaces that progressively
emerge from the liquid.
[0031] After the liquid has been completely drained from the tank 1, the incoming hot vapor
raises the temperature of the article surfaces so that their temperature tends to
equal that of the incoming vapor.
[0032] The valve 15 is then closed thus stopping the admission of the vapor, and by opening
tha valve 17 the tank 1, now emptied of any liquid, is communicated with the cooling
and condensing device (condenser) 4, schematically represented in Fig. 1 by a tank
housing a coil 21 in which a refrigerator flows. The vapor from the tank 1 progressively
expands in the condenser 4 and the condensated vapor is collected within the tank,
thus creating a vacuum within the tank 1. Since the articles are at a suitable temperature
and are covered by a liquid film, the vacuum causes the boiling of the liquid film.
The thermal content of the articles can be enough to continue the boiling process
until the complete vaporization of the liquid covering the articles, also thanks to
the degree of the vacuum produced.
[0033] In case the articles are not completely dry at the end of the above vacuum forming
stage, due to an insufficient amount of thermal energy stored by them, another drying
cycle is carried out. Hot vapor is again admitted into the tank 1, then this additional
admission is stopped and vacuum is again generated in the tank 1, so that the liquid
film over the articles completely condensates and the article surfaces become completely
dried. If necessary two or more drying steps are carried out until the article surfaces
are completely dried.
[0034] When the articles are only to be dried, instead of being subjected to a full rinsing
and drying treatment, the above sequence of operations is corrispondently shortened.
More particularly, the articles are arranged within the tank 1 and the cover 2 is
airtigh closed. Then the tank 1 is communicated with the storage tank 8 by opening
the valve 11 so that the air within the tank 1 can migrate into tank 8, and the valve
15 towards the vapor generator 3 is opened. Then the valve 11 in the conduit communicating
the tank 1 with the tank 8 is closed, while maintaning open the valve 15 that allows
the admission into the tank 1 of vapor that heats the articles.
[0035] Once a desired level of heating (i.e. thermal energy stored by the articles) has
been reached, the admission of vapor is stopped and the tank 1 is communicated with
the condenser 4, and in case with the ejector 6. This way an adequate vacuum level
is generated in the tank 1 for boiling the liquid film covering the articles as a
result of the condensation on their surfaces.
[0036] After a certain time interval, the whole liquid film covering the articles has been
evaporated, that is if the thermal energy stored by the articles is large enough.
In case the film is not completely evaporated, because of the small level of the thermal
energy stored in the articles, the cycle is repeated.
[0037] It is pointed out that in the initial stage of heating the articles, the vapor condensates
over the articles since it is warmer than the articles, thus forming a liquid film
that achieves a rinsing by dripping along theirs surfaces, and although modest this
rinsing is very effective, particularly at the interface liquid-vapor.
[0038] In the above described process the vacuum within the tank 1 has been generated by
the communication with the condenser 4. On the other hand, such vacuum could be generated
by cooling a surface 22 located within the tank 1, as shown in Fig. 2. This approach
can be either an alternative to the condenser or an addition to the condenser.
[0039] The invention accomplishes the following advantages over the prior art apparatuses
and processes.
- The time interval between two subsequent cycles are reduced.
- The articles are dried in an environment that is extremely clean and not oxidative.
- The drying temperature is kept low.
- The articles are cleaned at a very high degree (such as that required for example
in ball bearings, lenses of optical devices, in mechanical components using very thin
capillary tubes, etc.).
[0040] The process is ecological in that she emission of pollutants into the environment
is null or negligible, as a function of the type of fluid that is used.
[0041] The apparatus works with any type of fluid or other substance that is evaporable
at a pressure lower or higher than the atmospheric pressure.
[0042] When the articles do not require a particularly accurate washing, the process of
the invention can replace the whole washing cycle, while maintaining unaltered the
working principle.
1. A process for rinsing articles that have been subjected to a washing treatment, characterized
in that it comprises the steps of:
a) positioning the articles to be treated within a tank (1) and hermetically closing
said tank (1);
b) filling said tank (1) with a rinsing liquid, while at the same time expelling the
air present in the tank (1);
c) slowly draining the rinsing liquid from said tank (1) while at the same time admitting
into said tank (1) a flow of hot vapor so that the vapor condensates over the surfaces
of the articles progressively emerging from the descending rinsing liquid, whereby
an additional washing is obtained by the dripping of the liquid film covering said
articles;
d) maintaing the flow of hot vapor after the complete drainage of the rinsing liquid
and until said articles store a given amount of thermal energy;
e) stopping the flow of hot vapor and creating a vacuum within said tank (1) for causing
boiling of the liquid film covering the articles until they are completely dry;
f) opening said tank (1) and removing said rinsed and dried articles.
2. A process as claimed in claim 1, characterized in that said vacuum is generated by
communicating said tank (1) with a cooling and condensing device (4).
3. A process as claimed in claim 1, characterized in that said vacuum is generated by
cooling a surface (22) located within the tank (1A).
4. A process as claimed in the preceding claims, characterized in that said articles
in the rinsing tank (1) are initially cooled by the rinsing liquid so that when said
rinsing liquid is slowly drained their emerging portions act as condensation bodies
for the incoming hot vapor and are covered by a liquid film that drips down the article
surfaces achieving a microwashing of said surfaces.
5. An apparatus for rinsing articles that have been subjected to a washing treatment,
characterized in that it comprises
- at least a rinsing tank (1) that can be hermetically closed by means of a cover
(2) for containing said articles;
- a vapor generator (3) connected to said tank (1) through a valve (15);
- a vapor cooling and condensing device (4) connected to said tank (1) through a valve
(17);
- a pumping assembly (7) connected to the tank (1) through a valve (12) for pumping
the rinsing liquid into said tank (1) and for extracting said rinsing liquid therefrom.
6. An apparatus as claimed in claim 5, characterized in that it further comprises a storage
tank (8) communicating with said tank (1) through a valve (11) for storing the air
expelled from the tank (1) when the rinsing fluid is polluting or harmful.
7. An apparatus as claimed in claim 5 or 6, characterized in that it further comprises
a cooling device (5) including a cylinder-piston assembly (27), a refrigerating coil
(28) and a fan (29) and communicating through a valve (21) with said cooling and condensing
device (4).
8. An apparatus as claimed in claims 5 to 7, characterized in that it further comprises
a pump-ejector assembly (6) for extracting from the tank (1) condensed fluids and
gases that have not condensated when the tank is in a vacuum condition, said pump-ejector
assembly (6) including an ejector (23), a pump (24) and a second condenser (25), with
said ejector (23) communicating with said cooling and condensing device (4), and a
valve (18) being located between the second condenser (25) and the cooling device
(5).
9. An apparatus as claimed in claims 5 to 8, characterized in that a plate (22) that
can be cooled by a coil (26) is provided within the tank (1A).
10. An apparatus as claimed in claims 5 to 9, characterized in that it comprises two tanks.