FR2594149A1 - Process making it possible to monitor the contamination of the solvent in dry-cleaning installations and monitoring appliance comprising novel types of sensors making it possible to carry it out - Google Patents

Abstract

Process making it possible to monitor the contamination of the solvent in dry-cleaning installations. According to this process, a simultaneous measurement of the density and of the transmission index of the solvent on the circuit itself is carried out making it possible to recycle it on the processing machine. For this purpose, an appliance consisting of an assembly 2 mounted on the outlet pipe 8 and the pipe 10 feeding the solvent to the processing machine 3 is used, this assembly 2 comprising, on the one hand, a sensor 14 making it possible to measure the density of the solvent sample taken and, on the other hand, a sensor 15, itself making it possible to measure the transmission index of the light beam through said sample.

Description

PROCESS FOR CONTROLLING SOIL ~
SOLVENT ON DRY CLEANING INSTALLATIONS AND
MONITORING APPARATUS HAVING NEW TYPES OF
SENSORS ALLOWING ITS IMPLEMENTATION.

 The present invention relates to a process for controlling the soiling of the solvent on dry cleaning installations for textile articles. It also relates to a monitoring device comprising new types of sensors allowing the implementation of this process.

 The technique of dry cleaning textile articles has been known for a very long time and will therefore not be described in detail. In general, this technique consists in bubbling the textile articles to be cleaned in a rotary drum containing an appropriate solvent, generally perchlorethylene, then in separating the cleaning solvent from the articles, in particular by spinning and finally, in drying the articles. treated textiles, always placed in the drum, by circulating in it a current of hot air intended to entrain the residual solvent contained in the articles.

 In such installations, the solvent follows a closed circuit and is recycled after each treatment.

Of course, the solvent is gradually loaded with fats and dyes and it must be regenerated periodically.

 The soiling of the solvent results, on the one hand, from what one might call its "normal wear and tear", the solvent gradually loading with fat and other impurities as the successive cleaning cycles are carried out, and on the other hand, accidental bleeding of dyes.

 Consequently, there arises on all these installations the problem of controlling the soiling of the solvent. To date, the main means of verification has been a simple visual inspection by the operator who, for example, detects normal wear and tear when halos appear on articles after cleaning. It is obvious that such a visual inspection is not sufficient.

 Another solution consists in checking the filters provided on the solvent recycling circuit. Such a measurement however lacks precision and does not give the degree of fouling of the solvent.

 The only precise and reliable solution allowing to control with certainty the staining of the solvent is, to date, the control in laboratory where one determines the rate of nonvolatile residues and the acid number.

It is obvious that such a solution is not applicable industrially.

 However, we have found, and this is what is the subject of the present invention, a simple, precise process which makes it possible to instantly control the rate of soiling of solvents, and this, on the cleaning installation itself without any intervention operator.

In general, the invention therefore relates to a method making it possible to continuously control the soiling of the solvent on dry cleaning installations for textile articles, said method being characterized by the fact that a simultaneous measurement of the density and the transmission index of the solvent on the same circuit allowing it to be recycled in the
cleaning machine.

Thanks to such a measure, it is possible to deter
undermine the decrease in solvent density, its coloring and
its opacity which results as well from normal wear
than an accidental disgorgement.

In accordance with the process according to the invention, the measurement
re density is achieved by determining a value
threshold on the difference in densities between a sample
of clean solvent and a sample of solvent used
dried on the machine, this information being provided either
on a voltage logger or a set of vi
light sualisation or any other equivalent system
to alert the user, for example by a
audible alarm.

The measurement of the transmission index, in accordance
to the invention, is carried out by subjecting a sample of solvent taken from the recycling circuit of the
machine with light beams at different lengths
waves and which are picked up by receiving elements
of the photoresistor type mounted in comparator, each
on a comparator amplifier circuit on which
can set a switching threshold commander
the switching on of a threshold display diode De
preferably the wavelengths are chosen for
check the three most frequent colors for the
solvent colored by dislodgement or aging, at
know blue (jeans), red (most common case),
yellow (beginning of browning of the solvent).

For the implementation of the invention, use will be made
new types of sensors including the structure and
operation will emerge more clearly from the description which follows and which are also the subject of the invention.

The invention will however be better understood thanks to the embodiment given below given by way of non-limiting example and which is illustrated by the appended diagrams in which
- Figure 1 is a schematic view of a dry cleaning installation equipped with an apparatus for controlling the soiling of the solvent and which is produced according to the invention;
- Figure 2 is a diagram of an optical sensor that includes such an apparatus and which allows the implementation of the method according to the invention;
- Figure 3 is the electronic diagram of a comparator which is associated with such an optical sensor unit
- Figure 4 is a sc-thematic view of a pressure sensor block used for the implementation of the method according to the invention.

 FIG. 1 is a schematic view of a dry cleaning installation, designated by the general reference (1), installation which will not be described in detail by the fact that it is conventional and which is equipped with an apparatus, designated by the general reference (2), produced in accordance with the invention and which makes it possible to control the soiling of the solvent.

 Generally, in such an installation, the solvent circuit used to carry out the cleaning treatment inside the enclosure (3) containing the articles to be treated works in a closed circuit. This solvent circuit essentially consists of a reservoir (4), a pump (5), a filter (6), these various elements being interconnected by means of pipes (7,8,9 , 10) which, in the following description will be designated respectively by the expressions "return line (7)", outlet line (8) "," connecting line (9) "," supply line (10 ) "which therefore constitute the solvent recycling circuit.

 According to the invention, on this recycling circuit, and particularly between the outlet pipe (8) and the supply pipe (10), is mounted an assembly (2) which allows, according to the invention, perform a simultaneous measurement of the density and the transmission index of the solvent. This assembly (2) is mounted in parallel between the outlet pipe (8) (or possibly directly on the tank (4)) and the supply pipe (10), this by means of a branch circuit (11). Such a bypass circuit (11) essentially consists of a vertical column connected to the pipes (8) and (10) by means of conventional valves (12, 13) and which make it possible to take samples at determined time intervals.

 The sampling column (11) is, at least in the area of the device (2) making it possible to carry out the transmission measurement according to the invention, made of a material capable of being traversed by light rays (tubes of glass for example).

 According to the invention, such an assembly (2) comprises, on the one hand, a sensor (14) making it possible to measure the density of the sample of solvent removed and a sensor (15) making it possible, for its part, to measure the transmission index of light rays through said sample.

 The density is measured by means of a pressure sensor which is also part of the invention, and which is illustrated in more detail in FIG. 4. Such a pressure sensor (14) is essentially in the form of a block (16) designed so as to be able to make it possible to carry out a differential measurement between a sample of solvent taken from the recycling circuit of the installation and a sample of pure solvent having a well-defined density (for example pure perchlorethylene having a density of 1.620 at 20 ° C.).

 To do this, this sensor is, on the one hand, designed so that it can be mounted on the sampling column (21) so as to have, above its orifice (17) a height H of determined dirty solvent therefore allowing to measure the pressure P1 exerted by said solvent on the pressure gauge (228 and, on the other hand, comprises, associated with its orifice (18), a second column (19), of the same height H, containing a perfectly pure solvent (perchlorethylene for example) and which also acts on the gauge (22) but in opposite direction. The circuits connecting the gauge (22) to the two columns include a three-way valve (23) on the soiled solvent side and a two-way valve (24) mechanically coupled to the three-way valve.

In one position, the valves (23,24) put each of the columns (21-19) in communication with one another under pressure on the sensor, the second position allowing on the one hand the evacuation of the column (21) through the orifice ( 11) and, on the other hand, the isolation of the column (19) of the sensor.

 A flexible membrane (20) is provided at the top of this column (19) in order, on the one hand, to avoid evaporation and, on the other hand, to allow setting to atmospheric pressure. The two columns thus formed are preferably made of copper, thermally bridged and heat-insulated to allow temperature equality. As an indication, if the column (19) has a height of 1.20 m, the column (21) containing the dirty solvent will have a similar height. The pressure exerted by the column (20), if it contains perfectly pure perchlorethylene, having a density of 1.620 at 206C, will therefore exert a pressure of 194.4 millibars.

 The other column (21) containing the more or less dirty solvent will exert a different pressure, for example if the sample has a density of 1.612, the pressure exerted will be 193.4 millibars. As a result, the differential measurement will make it possible to detect a voltage of 72.5 millivolts. It is therefore possible, under these conditions, to obtain a threshold value on the difference in densities, the information being supplied on a voltage recorder.

 The measurement of the transmission index making it possible to determine the coloration and the opacity of the solvent resulting both from normal wear and from accidental disgorging is carried out by means of the optical sensor (15), an embodiment is illustrated in FIGS. 2 and 3. Such a measurement is carried out by mounting said sensor (15) on the sampling column (11). In this embodiment, the sensor (15) comprises three light elements (22a, 22b, 22c) of LED technology, these three light elements being supplied by constant current and emitting respectively in red (650 nm), orange- yellow (580 nm), and green (510 nm).

 Three receiving elements of the photoresistor type (23a, 23b, 23c) are placed opposite each of the transmitters.

 The photoresistors are mounted in a bridge, each in a comparator amplifier circuit (see Figure 3a), on which a switching threshold can be set.

 The comparators control the lighting of a threshold display diode.

 The transmitter-receiver pairs (22a, 23ai 22b, 23bA 22c, 23c) are tightly mounted in a brass block (24) connected to the copper conduits (19, 21) of the pressure sensor (14). Of course, the measurement is carried out only on the only sample of soiled solvent. The sample of solvent to be measured is interposed between the emitter and the receiver and therefore causes absorption of light. Thanks to such a sensor, it is therefore possible to measure the percentage of transmission at different wavelengths corresponding to three colors. the most frequently present during soiling of the solvent, namely blue (jeans), red (most common case), yellow (beginning of browning of the solvent), these colors being detected respectively around 500 to 550 nm for red ( which corresponds to the green ray), while blue is very well detected around 600 at 680 nm, which corresponds to red, the browning of the solvent being detected by the simultaneous weakening of the three colors.

 Thanks to such an installation, it is therefore possible to permanently control the drop in density of a solvent, its coloration and its opacity which results both from normal "wear" and from accidental disgorgement.

 Of course, the invention is not limited to the exemplary embodiment described above, but it covers all the variants produced in the same spirit.

 Thus, for example, it could be envisaged to carry out only one control of the density or on the contrary a single control of the coloring.

Claims (7)

 1 / Method for controlling the soiling of the solvent on dry cleaning installations for textile articles, characterized in that a simultaneous measurement of density and of the solvent transmission index is carried out on the same circuit allowing to recycle it in the cleaning machine.  2 / A method according to claim 1, characterized in that the density measurement is carried out by examining a threshold value on the difference in densities between a sample of clean solvent and a sample of solvent used on the machine, this information being supplied either on a voltage recorder or to a light display unit or any other equivalent system enabling the user to be alerted, for example, by an audible warning device.  3 / A method according to claim 1, characterized in that the measurement of the transmission index is carried out by subjecting a sample of solvent taken from the recycling circuit of the machine to light beams at different wavelengths and which are picked up by photoresistor type receiver elements mounted in comparator, each on a comparator amplifier circuit on which a switching threshold can be controlled controlling the switching on of a threshold display diode.  4 / A method according to claim 3, characterized in that the wavelengths are chosen to control the three most common colors for the dye, namely blue (jeans), red (most common), yellow (beginning of solvent browning).  5 / Apparatus for implementing the method according to one of claims 1 to 4, characterized in that it is constituted by an assembly (2), mounted between the outlet pipe (8) and the pipe supply (10) of the solvent to the treatment machine (3), this assembly (2) comprising, on the one hand, a sensor tel4) making it possible to measure the density of the sample of the solvent withdrawn and, on the other hand, a sensor (15) for its part, measuring the index of transmission of light rays through said sample.  6 / pressure sensor (14) allowing the implementation of the method according to one of claims 1 to 4, characterized in that it is in the form of a block (16) for performing a measurement differential between a sample of solvent taken from the recycling circuit (8) of the installation and a sample of pure solvent having a well-defined density, said sensor being designed to be mounted on a sampling column (linked to the pipes (8, 10) of the recycling circuit in order to have, above its orifice (17), a height H of determined dirty solvent therefore making it possible to measure the pressure P1 exerted by said solvent and comprising, on the other hand, associated at its orifice (18), a second column (19), of the same height H containing a perfectly pure solvent.  7 / sensor (14) for measuring the transmission index of the solvent on the same circuit allowing it to be recycled in the cleaning machine for the implementation of the method according to one of claims 1 to 4, characterized by the fact that it comprises three light elements (22a, 22b, 22c) of LED technology, these three light elements being supplied by constant current and emitting respectively in red (650 nm), yellow-orange (580 nm) and green (510 nm), said sensor being mounted on a sampling column (11) disposed as a bypass on the solvent recycling circuit.