EP0384864A1 - Purification device for a machine for cleaning various articles with a hot solvent, and machine for using same - Google Patents

Abstract

Machine for cleaning various articles with a hot solvent medium with a purifying capacity (18): - provided at its base with an evaporator (19) associated with heating means (20) and extended by a bottom conduit (22) for removing the impurities separated off, - intended to be connected to the distillation compartment (4) by a controlled transfer means (21) opening below the level of the liquid phase (5) present in the said compartment, - and intended to open, via its substantially upper part (23), into the distillation compartment above the liquid phase present in the latter, but within the vapour phase. <IMAGE>

Description

The present invention relates to the field of cleaning of parts, objects or various articles, by means of a solvent medium, generally relatively hot and comprising a liquid phase and a vapor phase with which said parts are brought into contact by relative displacement, more generally imposed on the parts themselves according to a continuous path inside the machine, between an entry station and an exit station.

The object of the invention relates, more particularly, to machines of an industrial nature, used for pickling, cleaning and degreasing of industrial parts, of any acceptable size, adapted, for the needs of the cause, on a through conveyor the machine.

The invention relates, more particularly, to machines of the above type using, as the solvent medium, chlorinated, fluorochlorinated, alcohol and other solvent components, used with steam generation and steam condensation system.

In machines of the above type, it is necessary to produce a high generation of vapor from the solvent medium, in order to benefit from two important advantages. The first is to provide a vapor medium free of dirt, allowing a final rinsing of the cleaned parts as soon as they leave the liquid bath in which they were immersed. This rinsing function intervenes by the condensation of the vapor phase on the parts leaving the cleaning bath. The second consists of a regeneration function for the soiled liquid solvent medium, in order to be able to supply clean condensate to the liquid bath in which the parts to be cleaned are soaked.

To this end, traditional cleaning machines and, in particular, that disclosed by document DE-A-1 956 854 , comprise a compartment, called cleaning, and a compartment, called regeneration or distillation, in which the overflow of cleaning bath is spilled. Heating means, associated with this regeneration compartment, allow the production of a steam continuously which has the two advantages above.

Machines of the above type must have significant storage and heating means for the distillation compartment, so as to be able to produce a total regeneration of the quantity of solvent medium in a relatively short time, generally close to one hour.

When dirt and other impurities, extracted from parts, products, articles or objects passing through the bath of the cleaning compartment, accumulate in a too high percentage of concentration in the distillation compartment, the boiling point of the solvent medium, at inside the latter, increases significantly. If the heating power specific to this distillation compartment is not increased, the quantity of steam produced decreases at the same time as this steam becomes less and less clean.

In practice, it is not possible to allow the concentration of dirt and impurities in the solvent medium distillation compartment to increase beyond a certain value. It is also not conceivable, practically, to significantly increase the heating power of such a compartment, especially if the solvent medium is based on chlorinated solvents which contain stabilizing adjuvants which cannot be subjected to a temperature excessive and critical, such as 120 ° C for trichlorethylene. Indeed, it is known that beyond such a critical temperature, overheating of the solvent medium produces the formation of acids which can then deteriorate the entire machine and ultimately cause problems of security.

To solve this problem, it is usual to empty the distillation compartment of a cleaning machine when the concentration of impurities exceeds a critical threshold, for example around 30%. This emptying operation is unpleasant, unsanitary, cannot be completed in a timely manner brief and interrupts machine operation.

In addition, the polluted solvent medium must be either destroyed or transported to a recovery installation, in which an advanced distillation is carried out to regenerate the solvent medium, in order to reconstitute it subsequently for a new use. Transport and advanced distillation entail a very high processing cost.

To try to minimize this cost, it is known to add, to a cleaning machine of the above type, an additional distiller which is, in a way, constituted in the form of a distillation compartment of the same structure as that of the machine, but provided with own heating means and specific condensing means to produce, from the steam generated, a condensate which is recycled in the main machine.

The auxiliary distiller can be fed continuously and allows over-concentration of impurities and dirt, for example up to 70%.

It is understood that, when the maximum concentration level is reached, it is again necessary to proceed with the complete emptying of the auxiliary distiller which is in a state of stop of operation.

The solution, consisting in resorting to the existence of an additional distiller, is not satisfactory for the following various reasons.

It is clear that such an additional distiller requires, for its operation, heating means, cooling means, water separation means, recirculation means, which very significantly increase the installation price, operation and maintenance.

It is also important to note that the recirculation of the liquid solvent medium, from the additional distiller, is carried out by transfer of the condensates, that is to say from a liquid phase towards the cleaning machine. main. These recycled condensates do not have the same temperature as those of the main machine and their incorporation into the solvent medium in use, significantly disturbs the thermal equilibrium of operation of the main machine. It is then necessary to provide for the installation of temperature regulation means which significantly increase the price of the entire installation by requiring, in addition, the frequent presence of qualified supervisory personnel to bring about the variations in adjustment. necessary, depending on the modification of the conditions of the cleaning process and the regeneration process.

Since the recovery, from the additional distiller, is carried out by the condensates recovered, these must, obligatorily, pass through a water separator before being recycled in the main machine. Such a separator represents a source of losses of the solvent medium and of the additives which enter into its composition. The solvent recovered is therefore no longer gradually capable of properly assuming the task assigned to it.

It is also important to note that an additional distiller of the above type has, at the top, an air-vapor interface overcoming the condensation zone and which always generates a loss of solvent by diffusion in the 'air. In addition, there is a risk of pollution of the surrounding atmosphere in the event that the condensation conditions are not optimal.

Another drawback of an annex distiller open at the top is that it allows non-specially qualified personnel to pour, inside the annex distiller, various products which do not necessarily have all the compatibility required with the solvent medium. during treatment, in particular, a chlorinated solvent close to that during treatment, but not identical.

It is also important to remember that a cleaning installation thus constituted implies the circulation, for the operation of the main machine, of a quantity of medium. solvent significantly greater than that usually required, since it is necessary to be able to maintain the functions of condensation, distillation and recirculation in two separate machines, but operating, in a way, in series.

It is also useful to note that the presence of an annex distiller implies an increased occupancy on the ground and limits, consequently, the establishment of production units that really generate economic gains.

Due to the relatively large mass of solvent medium to be treated and the relocation in relation to the main machine, the additional distiller necessarily involves the provision of significant heating means which are a non-negligible increasing source of consumption, in significant proportions, the operating cost of the main machine. In addition, the distillation is not sufficiently advanced and the discharges of polluted solvents are significant.

The present invention aims to propose a new cleaning machine whose general structure is of the type of that of conventional machines, but which has improvements capable of solving the problem posed by the need to carry out an advanced regeneration phase of the solvent medium. to extract from the latter the impurities and dirt which accumulate as the machine operates.

Another object of the invention is to provide or equip a cleaning machine, with a view to achieving high regeneration, by means of continuous purification, without interruption of operation over time, or loss of yield due to fouling. of the machine.

An object of the invention is to propose improvements which can be made to existing machines for a clean cost price and a low installation cost.

Another object of the invention is to propose improvements which can be easily adapted to existing machines or, again, an initial installation when designing new cleaning machines.

An additional object of the invention is to make it possible to purify the solvent medium, without degrading its composition and, more particularly, that of the additives provided to give it characteristics of stability, resistance to heat, solubility, vaporization, condensation and non chemical attack.

Yet another object of the invention is to propose improvements capable of solving the problem mentioned above and offering, in addition, to the user, a certain guarantee against any risk of introduction or incorporation of products, solvents or no, incompatible with the charge of solvent medium used for its operation.

To achieve the above objectives, the purifier according to the invention is characterized in that it comprises a purifying capacity:
- provided at its base with an evaporator associated with heating means and extended by a low duct for removing separated impurities,
- intended to be connected to the distillation compartment of a machine to be cleaned by a controlled transfer means opening below the level of the liquid phase contained in said compartment,
- And intended to open, through its substantially upper part, into the distillation compartment, above the liquid phase contained by the latter, but inside the vapor phase.

• La fig. 1 est une coupe transversale d'une machine de nettoyage conforme à l'invention.
• La fig. 2 est une coupe transversale partielle illustrant une variante de réalisation.
• La fig. 3 est une coupe transversale partielle prise selon la ligne III-III de la fig. 2.
• Les fig. 4 et 5 sont des vues schématiques mettant en évidence différentes possibilités de réalisation de l'un des éléments constitutifs de la machine.
• La fig. 6 est une coupe transversale illustrant une autre variante de réalisation de la machine.

Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments of the subject of the invention.

• Fig. 1 is a cross section of a cleaning according to the invention.
• Fig. 2 is a partial cross section illustrating an alternative embodiment.
• Fig. 3 is a partial cross section taken along line III-III of FIG. 2 .
• Figs. 4 and 5 are schematic views showing different possibilities of making one of the constituent elements of the machine.
• Fig. 6 is a cross section illustrating another alternative embodiment of the machine.

The invention relates to improvements made to a machine 1 for cleaning parts, products, articles or various objects via a hot solvent medium. Generally and usually, a machine 1 comprises a tank 2 delimiting a first compartment 3 , called cleaning, and a second compartment 4 , called distillation, preferably extending parallel to the first.

The cleaning compartment 3 is used for immersion of the parts or objects to be cleaned and contains a given quantity 5 of a solvent medium in liquid phase which is maintained by the operation of the machine at a temperature compatible with its composition. The solvent medium is chosen to favor the action of cleaning, degreasing, cleaning. Generally, it is also planned to couple the bottom of the compartment 3 with ultrasonic generators 6 and heating means.

The cleaning compartment 3 can communicate, by an overflow overflow threshold 7 , with the compartment 4 which is also intended to contain a quantity of solvent medium 5 in the liquid phase. The compartment 4 is associated with heating means 8 which are, for example, constituted by one or more resistors provided with regulation means controlled by a temperature sensor influenced by the liquid phase of the soiled solvent medium contained in compartment 4 .

The compartments 3 and 4 open, by their upper part, inside the tank 2 and below a zone of condensation 9 which is vertically delimited, in particular by means of one or more cooling coils 10 bordering the upper peripheral wall of the tank 2 . In a known manner, the condensation zone 9 is surmounted by a guard zone 10 which is established up to the level of the open upper section 12 of the tank 2 .

The condensation zone 9 comprises at least one gutter 13 for recovering the condensates forming on the coil 10 , from the steam generated in the compartment 4 . The gutter 13 is connected, by a transfer pipe 14, to a water separator 15 comprising an outlet 16 and a pipe 17 for recirculating condensates in liquid phase in the cleaning compartment 3 .

According to the invention, the machine described above is provided with a purifying capacity 18 , the lower part of which is occupied by an evaporator 19 . The capacity 18 is provided with own heating means 20 and is connected, to the distillation compartment 4 , by a transfer means 21 consisting, in the present case, of a pipe opening, on the one hand, below the level of the liquid phase of the solvent medium 5 occupying the compartment 4 and, on the other hand, above the evaporator 19 . The purifying capacity 18 has a low discharge conduit 22 and is connected to the compartment 4 by an upper communication 23 opening above the level of the liquid phase 5 .

In the embodiment illustrated in FIG. 1 , the capacity 18 represents an annex module located outside the tank 2 and is connected to the latter by a pipe 21 and by a high pipe 23 .

According to one provision of the invention, the transfer means 21 is provided with means 24 for controlling the flow rate of the solvent medium established between the compartment 4 and the capacity 18 . Likewise, the means 21 communicate with a generator 25 forming part of the evaporator 19 and capable of producing a thin layer on a flow wall 26 leading to the evacuation duct 22 . The wall 26 has at least one inclination, relative to the horizontal, which can be constant or not and even vertical.

The capacity according to the invention operates as follows.

The overflow of the polluted solvent medium, occupying compartment 3 , is evacuated by pouring into the distillation compartment 4 to maintain the amount of liquid phase inside the latter. The heating means 8 generate, from this liquid phase, a vapor phase which is brought to occupy the upper part of the tank 2 where it is in contact with the coil 10 . The resulting condensation is recovered by the gutter 13 and the evacuated condensates are directed to the separator 15 so as to be free of the fraction of water which they have incorporated during the condensation phase. The condensates from the separator 15 are recycled to compartment 3 .

Either continuously, or when the pollution of the liquid phase of the solvent medium occupying compartment 4 increases beyond an unacceptable concentration, a transfer is ensured, via the line 21 , so as to supply the generator 25 to allow proper operation of the evaporator 19 . By the heating means 20 , the fluid medium, established in a thin layer on the wall 26 , evaporates while leaving the dirt or impurities which are evacuated through the conduit 22 . The vapor phase, produced in the purification capacity 18 , is returned, by communication 23 , to the distillation compartment 4 , but in the part of the latter occupied by the vapor phase generated from the quantity of soiled fluid medium occupying a such compartment. This additional vapor phase completes that of the main distillation compartment 4 and then follows the same condensation-recirculation cycle.

The improvements according to the invention involve a recycling capacity of small volume which does not imply increasing the load of solvent medium necessary for the operation of the machine.

The recycling of the steam produced inside the tank 18 takes place in the steam phase from the distillation compartment 4 and therefore does not disturb the thermal equilibrium of operation of the machine 1 .

Since the supply of the capacity 18 takes place at low flow rate from the liquid medium occupying the distillation compartment 4 , it is not necessary to add, to the capacity 18 , particularly high heating means. As the same overall mass of solvent medium, the heating means 20 can be considered in power as being part of the maximum power that it would normally be necessary to implement to operate the machine from the single compartment of distillation 4 . In any case, if this is necessary, due to the fact that the other elements of the machine have been calculated as accurately as possible, it would be possible to reduce the power of the heating means 8 by the amount corresponding to that of the means 20 to find the machine functioning identical to that which existed before the addition of the purifier 19 .

The particularly advantageous heat balance is also due to the fact that the purifier 19 is preferably of the thin film type, allowing the formation of a vapor phase by maintaining a constant temperature, regulated by means heater 20 of relatively low power. The purifier 19 is also preferably of the steam type to avoid any hot spot. Such a thin film evaporator facilitates the evaporation of the solvent medium and increases the percentage of concentration of impurities, beyond 80%.

In addition to the above advantages, it should be considered that the improvements according to the invention do not require the presence of an additional machine, large in volume and in surface area occupied, nor the connection and connection to sources of clean power complicating the overall installation.

It is important to note, also, the absence requirement for a clean water separator, since the steam generated in capacity 18 is returned to the steam zone of the distillation compartment 4 .

In addition to the above advantages, it is clear that the solvent medium is not subjected to any rise in temperature beyond the critical operating temperature and can therefore be recycled many times without risk of degradation of its composition.

The presence of the completely closed capacity 18 moreover prohibits that, by clumsy, unfortunate or careless handling, any charge of product, incompatible with the nature of the solvent medium necessary for the machine, is introduced into the latter.

Furthermore, the presence of the capacity 18 does not increase the air-vapor interface of the whole machine and does not increase the consumption of solvent by diffusion into the air, nor the risks of atmospheric pollution.

In order to obtain regular operation of the capacity 18, it is important, within the meaning of the invention, to ensure a controlled supply of the generator 25 . To this end, the means 24 can consist of an adjustable flow limiter, interposed on the pipe 21 . The adjustable flow restrictor could also be replaced by a variable flow pump immersed in compartment 4 .

Fig. 2 shows an alternative embodiment according to which the capacity 18 , always arranged by external adaptation to the tank 2 , comprises an evaporator 19 which is constituted by a body of revolution produced, for example, in the form of a tubular cylindrical envelope forming the wall 26 by its inner surface, as shown in FIG. 3 . The wall 26 is associated with a generator 25 which distributes the liquid to be purified along the wall. This generator can be constituted in the form of a mobile comprising, at least, a scraper 28 driven in rotation, for example in the direction of the arrow f₁ , by a suitable motor member. This arrangement ensures self-cleaning of the capacity 18 by permanent and continuous scraping of the thin layer, in this case the wall 26 , and avoids a reduction in time of the yield of the capacity 18 and, consequently, of the whole machine.

Fig. 4 shows that the evaporator 19 can also be constituted by a body 29 of cylindrical shape on the outer peripheral wall of which is caused to rub a scraper 30 belonging to a mobile moving in rotation coaxially with the cylinder 29 .

Fig. 5 shows another alternative embodiment in which the evaporator comprises a body 31 having a surface 32 of revolution, for example in a cylindrical segment, relative to which can be moved a scraper 33 capable of being driven by an alternating angular movement according to arrow f₂ by any suitable motor means.

Fig. 6 illustrates the details of an improvement made to the variants shown in FIGS. 2 to 5 . The modification consists in mounting, substantially at the upper part of the generator 25 , a cap 50 integral with the latter and driven in rotation by a pin 51 connected to a motorized drive means. The cap 50 is advantageously a body of revolution, of frustoconical shape, its large base disposed towards the generator 25 , its peripheral envelope 52 being substantially planar. The wall 26 , delimiting the evaporator and constituting, by its internal face, the thin layer, defines, at the periphery of the cover 50 , a chamber 53 , called pre-evaporation, connected by a communication 23 to the vapor phase 9 and by transfer means 21 to the liquid phase 5 . The transfer means 21 are arranged so as to open out at the upper part of the cover 50 , near its peripheral envelope 52 .

Thanks to this arrangement, one obtains, during the rotation of the generator 25 associated with the cover 50 , perfect spreading of the soiled solvent medium 5 on the casing 52 to form a film substantially increasing the evaporation of the recycled fluid medium and, correspondingly , the separation of dirt in chamber 53 . The fraction of the non-separated solvent medium then flows along from the wall 26 and the impurities and dirt are discharged through the bottom conduit 22 . The self-cleaning of the thin layer is ensured by scraper elements 28 arranged at the periphery and over the entire height of the generator 25 . It is also possible to provide, on the cover 50 and in its lower part or on the walls of the chamber 53 , scraping means, with a view to ensuring, also, self-cleaning of the chamber 53 .

It is advantageous, in such a case, for the transfer, between compartment 4 and the evaporator 19 , to involve a control means constituted by a variable flow pump 41 immersed in the liquid phase of compartment 4 and whose outlet s opens above the evaporator 19 by the generator 25 .

The example according to fig. 6 corresponds, more particularly, to a new design of a cleaning machine, while the previous examples are particularly suitable for separate manufacture and possible adaptation on already built machines and in actual use.

The invention is not limited to the examples described and shown, since various modifications can be made thereto without going beyond its scope.

Claims (10)

1 - Purifier for machine for cleaning various articles with a hot solvent medium, machine of the type comprising a tank ( 2 ) comprising a condensation zone ( 9 ) and delimiting, on the one hand, a first compartment ( 3 ), called cleaning, opening by its upper part in the tank ( 2 ) under the condensing zone ( 9 ) and into which opens a pipe ( 17 ) for recirculating condensates from the condensing zone ( 9 ) and, on the other hand, a second compartment ( 4 ), called the distillation compartment, opening by its upper part in the tank under the condensation zone, communicating with the first compartment by an overflow weir threshold ( 7 ), intended to contain a liquid phase of dirty solvent ( 5 ) and provided at its base with heating means,
characterized in that it has a purifying capacity ( 18 ):
- provided at its base with an evaporator ( 19 ) associated with heating means ( 20 ) and extended by a low pipe ( 22 ) for removing the separated impurities,
- intended to be connected to the distillation compartment ( 4 ) by a controlled transfer means ( 21 ) opening below the level of the liquid phase ( 5 ) contained in said compartment,
- And intended to open, through its substantially upper part ( 23 ), in the distillation compartment, above the liquid phase contained by the latter, but inside the vapor phase. 2 - Purifier according to claim 1, characterized in that the capacity ( 18 ) is provided with an evaporator ( 19 ) constituted by an inclined wall ( 26 ) associated with a generator ( 25 ) for flow of the solvent medium in a thin layer . 3 - Purifier according to claim 2, characterized in that the capacity ( 18 ) is provided with an evaporator ( 19 ) constituted by a body of revolution associated with a spreading mobile ( 25 ) moved in rotation coaxially with the body and comprising at least one scraper ( 28 ) of the wall of this body. 4 - Purifier according to claim 3, characterized in that the spreading mobile ( 25 ) comprises, substantially at its upper part, a cap ( 52 ) of frustoconical shape defining, with the wall 26 , a pre-evaporation chamber. 5 - Purifier according to one of claims 1 to 4, characterized in that the capacity ( 18 ) is external to the tank. 6 - Purifier according to one of the preceding claims, characterized in that the controlled transfer means ( 21 ), between the distillation compartment ( 4 ) and the capacity ( 19 ), is provided with flow control means ( 24 ) . 7 - Purifier according to claim 6, characterized in that the flow control means ( 24 ) comprise an adjustable flow limiter. 8 - Purifier according to claim 6, characterized in that the flow control means ( 24 ) comprise a variable flow pump ( 41 ). 9 - Purifier according to claim 1 or 6, characterized in that the transfer means ( 21 ) opens above the evaporator. 10 - Machine for cleaning various articles with a hot solvent medium, characterized in that it comprises a purifying capacity ( 18 ) according to one of claims 1 to 9.

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