EP0360866A1 - Method and installation for cleaning parts - Google Patents

Abstract

PCT No. PCT/SU88/00075 Sec. 371 Date Dec. 4, 1989 Sec. 102(e) Date Dec. 4, 1989 PCT Filed Mar. 29, 1988 PCT Pub. No. WO89/09099 PCT Pub. Date Oct. 5, 1989.The proposed method resides in that the surface of a workpiece is treated with a molten solvent which at first is crystallized at the surface of the workpiece and then is melted to result in a used solution which is cooled and settled to form two layers, viz., an upper layer containing petroleum products, light mechanical impurities and a quantity of the solvent, and a lower layer containing the solvent, heafy mechanical impurities and a quantity of petroleum products, after which petroleum products are separated from the upper layer, whereas, the crystals of the solvent are melted and added to the lower layer from which the solvent is separated and conveyed for cleaning the workpieces. An apparatus for carrying out the method comprises a system (12) for regenerating the used solution connected to a system (20) for separating constituents of the upper layer (18), and a system (21) for separating constituents of the lower layer (19).

Description

Field of the invention

The invention relates to the field of cleaning articles by ridding them of technological impurities, and more specifically, it relates to a cleaning process of articles by ridding them of petroleum products and mechanical impurities, and an installation for the realization of this method.

The invention can be applied with the greatest effect to the cleaning of the surface of articles contaminated with mineral oils, vegetable oils and animal fats, pasta, preservatives, cutting liquids and other technological impurities, referred to more far petroleum products and mechanical impurities.

State of the art

In modern production technology, a large number of auxiliary materials are involved. Mineral and vegetable oils and animal fats, pasta, preservatives, cutting liquids, etc. can be referred to. They remain on the surface of the items and require cleaning before assembly or application of a protective coating. In the descaling operations of the articles, use is made of hydrocarbon solvents, chlorinated and / or fluorinated hydrocarbon solvents, aqueous solutions of electrolytes, surface-active substances and complex mixtures based thereon. After the cleaning operation of the articles, they are, together with the impurities, all released into the environment in the form of industrial spills, vapors, waste incineration products. distillation, sludge to be buried. The price of irretrievable losses of chemical substances and the damage caused by environmental pollution are immense.

There is known a method of degreasing articles (SU-A-1093732). This method comprises treating the surface of the articles with aqueous solutions containing surface active substances and process activators, for example, ammonium persulfate, monoethanolamine phosphate, sulfamic acid, acid, and the like. oxalic acid, naphthalenesulfonates and water. Regeneration of spent solutions is carried out by decantation, removal of the oil products emerging on the surface of the solution and filtering of mechanical impurities.

In this process, the regeneration of the spent solution consists only in the settling and filtering of inhomogeneous systems. The spent solvent, polluted with soluble impurities, is not regenerated at all. Thus, aqueous solutions, and organic solvents and petroleum products are released into the environment.

A method of cleaning the surface of articles by removing petroleum products and mechanical impurities (SU-A-541857) is known in that the article to be cleaned is preheated to 60 ° C, is treated with a detergent containing white spirit, hydroxyl alkylphenols or fatty alcohol, water, sodium alkylsulfonate and gas oil. With this, the article is maintained for 10 to 15 minutes at a temperature of 50 to 60 ° C and the article is washed with an aqueous solution heated to 60 ° C and containing 0.1 to 0.3% tripolyphosphate and 0 1 to 1% of hydroxylated alkyl phenol. The spent solution is regenerated by heating it to a temperature of 80 to 90 ° C, and the supernatant petroleum product is removed, while the aqueous detergent solution is reused several times for cleaning.

However, during the cleaning operation of the articles, the solvent partially reacts with the impurities removed by washing. Petroleum products, greases and solid mechanical impurities, removed periodically from the process, contain solvent, products of its chemical reaction with impurities and must be buried.

The aqueous phase, after saturation in soluble components of the petroleum products, must also be buried.

There is known a method of removing hard surfaces from articles using organic substance compositions (SU-A-957672). The process consists in treating the hard surfaces with polyfluorinated ethers or with chlorinated and / or fluorinated alkanes with addition of perfluoro-alcohols, perfluoro-ethers and perfluoro acids in an amount of 0.02 to 1% by weight. Volatile solvents distribute the dissolved substance on the surface and, by volatilizing rapidly, release (disperse) the film of petroleum products from the surface. The consumption of the composition is equal to a few cm ³ per 100 p. square of surface. In the known process, the problem of separating spent solutions into initial constituents has not been solved for use in recycling and the consumption of detergents is rather high, whereas the volatile base, the fluorocarbon liquids, evaporate in the process. atmosphere, destroy the ozone layer of the atmosphere.

Also known is a method of cleaning the surface of articles (GB-A-2104104). According to this process, the The surface of the articles is cleaned with a circulating solvent composed of a liquid chlorinated hydrocarbon and a surfactant whose constituents are selected so that they do not mix and react with the technological impurities. The spent solution is regenerated by evaporation of the liquid chlorinated hydrocarbon. After condensation, the surfactant is added to the purified solvent and returned for repeated cleaning of the article. Impurities washed away after evaporation of the solvent must be separated from the surfactant substance for reuse. In the process, this operation is not performed while the process itself is applied only in a limited area: the cleaning of the surface of articles after application of protective coatings, but then there may be decomposition of the chlorinated solvent in the presence of water and metal chlorides with the formation of very toxic substances.

In order to carry out the known methods, it is possible to use the cleaning device for the surface of carousel-type articles, which is composed of standard assemblies corresponding to the type of the detergent solution or to the requirements of the technological operation (D-V Kampschulte et al., FRG, Somingen, "Ultrasonic and Ultrasonic Cleaning and Degreasing Facility"). The installation comprises a cleaning chamber equipped with a mechanical and ultrasonic activation device, cleaning, a distillation device, a device for separating solid mechanical impurities, condensers for trapping and condensing the vapors of the reactor. solvent. This plant is characterized by a low solvent utilization factor due to the decomposition and reaction of the solvent with the mechanical impurities removed by washing and the water and the burial of distillation residues containing a significant amount of solvent. Solvent losses in such plants are 0.1 to 0.5 kg per m ² of surface cleaned articles.

A method of cleaning articles by removing petroleum products and mechanical impurities, carried out in an installation (SU-A-1189515), comprising cleaning the surface of the articles with a circulating solvent, drying the cleaned articles, is known. the regeneration of the spent solution and the separation of impurities removed by washing. According to this method, the articles are heated to a required temperature and are treated with the circulating solvent. After cleaning, the article is dried under vacuum. Dried items are cooled and removed from the facility. The solvent vapors formed during drying are condensed and returned to the surface cleaning cycle of the articles. The spent solvent is regenerated by distillation. A distillate and a distillation residue are then formed containing nonvolatilized solvent, petroleum products and mechanical impurities removed by washing. The distillate is returned to the cleaning cycle and the liquid components of the distillation residue are filtered and reused.

This process is also characterized by large losses of solvent, caused by its high volatility, its evacuation with the distillation residue and also due to its chemical reaction with impurities washed out and water.

The plant for carrying out this method (SU-A-1189515) comprises a conveyor for moving the articles and, aligned, an inlet chamber, neutral chambers, a cleaning chamber equipped with a control system. solvent circulation, a drying chamber connected to a vacuum system, a condenser for trapping solvent vapors, a distiller, a distillate accumulator, a petroleum product collector and a filter for separating mechanical impurities. All rooms in the facility are hermetically closed with valves.

Presentation of the invention

The object of the invention is to create a method for cleaning articles consisting of removing them from petroleum products and mechanical impurities and an installation for its production that would make it possible to change the state of aggregation of the solid-state cleaning medium to the gaxous, to adjust the reciprocal solubility in the system "technological pollution - cleaning medium" and by this, to increase the efficiency of the cleaning of the articles, to reduce the losses of the cleaning medium and the amount of impurities removed by washing diffusing in the environment.

This problem is solved by the fact that in a method of cleaning articles consisting of removing petroleum products and mechanical impurities and comprising treating the surface of the articles with a circulating solvent, drying the cleaned articles, regenerating the spent solvent. , the capture of the solvent vapors contained in the air-vapor mixture and the separation of petroleum products and mechanical impurities, according to the invention, the surface treatment of the articles is carried out in a bath of molten solvent with crystallization of that on the surface of the articles followed by the melting of the crystals of the solvent, the spent solution is cooled to a temperature close to that of melting of the solvent and is decanted with formation of two layers: a layer containing the petroleum products, the low-weight mechanical impurities and a part of the solvent and a lower layer containing the solvent, the heavy mechanical impurities and a part of the petroleum products, then the upper layer is poured and cooled until complete crystallization of the solvent it contains, the petroleum products are separated, the solvent crystals are melted and mixed with the lower layer from which the solvent which is sent to the cleaning of the articles is separated, while the light mechanical impurities of the upper layer and the heavy mechanical impurities of the lower layer are dried and the solvent is separated which is also used to clean the articles.

Thus, the method makes it possible to increase the efficiency of the cleaning (the residual pollution of the surface of the articles after the cleaning composes 0.01 to 0.05 mg / cm ² ), to carry out a regeneration of the used solutions with the recycling of the solvent, to exclude losses from petroleum products, to separate petroleum products and mechanical impurities and to reduce their release into the environment.

It is recommended to use as solvent organic substances, solid under normal conditions, fluorinated and / or chlorinated, chemically inert, insoluble in petroleum products and can not dissolve the latter at temperatures below the melting temperature of the solvent.

The application of such solvents makes it possible to reduce their loss thanks to the absence of a chemical reaction between them and the impurities removed by washing, their low solubility in petroleum products and also thanks to the low values of the vapor pressure at above the solid solvent. In addition, the use of such solvents allows the impurities to be separated without changing the chemical composition or the properties of the solvents. Thus, one achieves practically a process entirely without rejections. For example, the solvent losses according to the proposed method do not exceed 4 g per m ² of treated article surface and at least 94% of the initial petroleum products introduced in the cleaning operation are extracted from the spent solutions. dirty items.

It is preferable to subject a part of the solvent to distillation, then to send the distillate formed for rinsing the articles and after this rinsing to direct the distillate again for distillation, while the distillation residue, containing the petroleum products. and a substantial amount of solvent must be combined with the spent solution.

The application of these operations makes it possible to increase the efficiency of the cleaning and also to reduce the losses of solvent and petroleum products. Residual fouling, after rinsing the surface of the articles with the solvent distillate, is 0.01 to 0.001 mg / cm.

The problem of preventing the release of solvent vapors into the atmosphere can be solved in that the air and vapors of the chlorinated and / or fluorinated organic solvent, after drying of the articles, are cooled to complete crystallization. solvent and then the solvent crystals are separated from the air.

It is preferable that sclvant crystals, separated from the air, be melted and used to rinse the articles. This operation makes it possible to increase the rate of use of the solvent.

It is also desirable to separate the products tankers of the upper layer of the solution used by filtering. The filtering is sufficiently effective when in the upper layer is an insignificant amount of mechanical impurities and the solvent crystals are sufficiently large.

In practice, it is possible to separate petroleum products from the top layer by centrifugation. Centrifugation is preferred for separating petroleum products from finely dispersed crystals and mechanical impurities.

The problem is also solved with the aid of an installation for carrying out the method comprising a chamber for cleaning the articles connected to a regeneration system of the spent solution, comprising a distiller and a distillate accumulator communicating with the latter, a chamber rinsing articles connected via a pump to the distillate accumulator, drying chamber of articles, means for moving articles through the chambers, a vacuum vacuum system and a trapping system solvent vapor, in which, according to the invention, the regeneration system of the spent solution is provided with a cooler for the spent solution, connected to a decanter for the separation of the spent solution in two layers: a layer upper and lower layer, said decanter is connected to a system for separating the constituents of the upper layer and to a system of of the constituents of the lower layer, the system for separating the constituents of the upper layer comprising, in series, a crystallizer and a device for separating the petroleum products, one of the outputs of the petroleum product separation device being connected to a collector of petroleum products, and his other outlet is connected to a solvent collector, having a heater and having a lower outlet which, via a pump, is connected to the inlet of the cooler of the spent solution, while the separation system of the components of the lower layer comprises, in series, a pump, a siphon washer and an evaporator with an incorporated heater, an upper outlet of the siphon washer being connected, via the heater, to the cleaning chamber, and a lower outlet, to the an evaporator of which one of the outlets is connected to the decanter and another to the collector of the solvent.

To obtain an even better cleaning of the articles, to obtain a distillate free of petroleum products and to reduce the losses of the solvent and the petroleum products, it is rational that the distiller has three tubes, one of which is connected, via from one pump, to the cooler inlet, another to the top outlet of the siphon and the third to the distillate accumulator.

It is useful for the solvent vapor collection system to be connected to the drying chamber and to include, in series, a refrigerator-crystallizer, a siphon and a filter connected to the vacuum system, which prevents the release of solvent vapors. in the atmosphere and ensures technology without residues.

It is recommended that the lower parts of the refrigerator-crystallizer, siphon and filter be heated and communicate with the distillate accumulator. This makes it possible to increase the rate of use of the solvent.

It is advantageous that the device for separating petroleum products comprises a container with a filter element, a mechanism for the unloading of solvent crystals and light mechanical impurities and tubing: heterogeneous mixture inlet, petroleum product outlet, solvent crystal outlet and light mechanical impurities and tubing output connected to the vacuum system. This virtually ensures the complete separation of petroleum products from solvent crystals and mechanical impurities. The petroleum products then contain no more than 0.2% (by weight) of solvent and can be used again for different purposes.

Practically, it is possible that the device for separating the petroleum products is designed in the form of a centrifuge provided with inlet tubes of the heterogeneous mixture, the exit of the petroleum products and the exit of the solvent crystals and the mechanical impurities.

Brief description of the drawings

• La figure 1 représente la vue générale d'une installation pour réaliser le procédé de nettoyage des articles consistant à les débarrasser des produits pétroliers et des impuretés mécaniques, selon l'invention;
• La figure 2 est un dispositif de séparation des produits pétroliers, selon l'invention;
• La figure 3 est un dispositif de séparation des produits pétroliers par centrifugeage, selon l'invention.

The present invention is enlightened by the following detailed description of a concrete example of its embodiment with reference to the appended drawings in which:

• FIG. 1 represents the general view of an installation for carrying out the cleaning process of the articles consisting in removing them from petroleum products and mechanical impurities, according to the invention;
• Figure 2 is a device for separating petroleum products, according to the invention;
• Figure 3 is a product separation device centrifugal oil tankers, according to the invention.

Best mode of realization of the invention

The articles, fouled by petroleum products and by mechanical particles, having the temperature of the production room, are treated with a molten solvent in circulation. At the initial stage of the treatment, the solvent, falling on the cold surface of the article, crystallizes by changing volume and displaces the solid mechanical impurities adhered to the surface of the article thereby reducing their adhesion to the surface . In further processing of the molten solvent articles, the articles are heated, the solvent is melted and the petroleum products and mechanical impurities are removed from the surface. Residual fouling at this stage amounts to 0.01 to 0.05 mg / cm ² _.

Then, the spent solution, representing a mixture of solvent, petroleum products, heavy and light mechanical impurities, is cooled to a temperature higher than that of the melting of the solvent of 1 to 10 ° C, there is then reduction of the solubility in the solvent-petroleum products system and two layers are formed: an upper layer, containing petroleum products, light mechanical impurities and partially dissolved solvent in the petroleum products, and a lower layer containing the solvent, the heavy mechanical impurities and petroleum products partially dissolved in the solvent.

The top layer is poured and cooled to room temperature. As a result, the solvent crystallizes. Petroleum products are separated from solvent crystals and light mechanical impurities by filtering or centrifugation. The solvent is then melted, separated from the light mechanical impurities and added to the lower layer. The lower layer is separated from the heavy mechanical impurities, while the solvent is returned to the cleaning of the articles. The light mechanical impurities of the upper layer and the heavy mechanical impurities of the lower layer are combined and dried so as to separate the solvent which is evaporated. The solvent is then condensed and used again to clean the items. Thus, the efficiency of the cleaning of the articles is increased by reducing the adhesion of the mechanical particles to the surface during the crystallization of the solvent on the surface of the articles and ensures a production without residues due to the cooling of the layer superior, the crystallization of the solvent as well as through the separation of petroleum products from the solvent that is returned for a new cleaning operation.

As the solvent for treating the articles, chlorinated and / or fluorinated organic materials which are solid under normal conditions, chemically inert and reciprocally insoluble with the petroleum products are used at a temperature lower than that of the melting of the solvent. They must be explosion-proof and flammable, non-toxic and allow, by using phase transformations during the variation of the temperature, to easily separate the petroleum products and the mechanical impurities. In addition, low vapor pressures above the solid solvent at room temperature make it possible to reduce the losses of solvent by discharges into the atmosphere.

In order to increase the efficiency of the cleaning and to reduce the residual pollution of the surface, the articles are rinsed with the solvent distillate. To this end, a Part of solvent, taken from the lower layer and free of heavy mechanical impurities, is subjected to distillation and the distillate is sent to rinse the articles. At the end of this stage, the residual pollution of the surface of the articles amounts to 0.01 to 0.001 mg / cm ² . After rinsing the articles, the solution contains the solvent and an insignificant amount of petroleum products dissolved therein. The solvent is again sent to the distillation, while the residue, formed as a result of the distillation of the solution and representing a mixture of petroleum products (95 to 70% of the mass) and solvent (5 to 30% of the mass), is combined in the spent solution and is then regenerated.

Thus, high cleaning efficiency of articles is achieved, solvent losses are reduced by regenerating the residue of the distillation operation and the efficiency of the distillation is also increased.

After rinsing, the articles are dried at a temperature higher than that of melting the solvent, under vacuum or with hot air.

The air and the vapors formed during the drying of the articles of chlorinated and / or fluorinated organic solvent are cooled to a normal temperature. The crystallization of the solvent then occurs.

Solvent crystals are filtered from the air, melted and used to rinse the articles. Thus, the solvent vapors are efficiently recovered by a simple technique and are used again during the cleaning operation of the articles.

The total losses of the solvent during the realization of the method described above do not exceed 0.004 kg per square meter of cleaned surface of articles, is extracted during the process at least 94% of petroleum products.

The proposed installation, carrying out the method of cleaning the surface of the articles, comprises a chamber 1 for cleaning articles 2, a chamber 3 for flushing where there are injectors 4 and ultrasonic sources 5, a chamber 6 for drying articles 2, having heating elements 7, which is connected to a solvent vapor collection system 8 and to a vacuum system 9. The chambers 1,3 and 6 are separated from each other and from the outside environment by valves 10. The installation comprises a means 11 for moving the articles in the chambers 1,3 and 6.

The cleaning chamber 1 of the articles 2 is connected to the regeneration system 12 of the spent solution, comprising a distiller 13, connected to a distillate accumulator 14, a cooler 15 of the spent solution connected to a decanter 16 provided with a heater 17 incorporated. The decanter 16 serves to separate the spent solution in two layers: upper 18 and lower 19, and is connected to a system 20 for separating the components (petroleum products, solvent dissolved in a small amount in the petroleum products, light mechanical impurities) of the upper layer 18, and a system 21 for separating the components (solvent, petroleum products dissolved in a small amount in the solvent, heavy mechanical impurities) of the lower layer 19. The system 20 for separating the components of the upper layer 18 comprises, connected in series, a crystallizer 22 and a device 23 for separating the petroleum products, an outlet 24 of the device 23 for separating the petroleum products which is connected to a collector 25 for the products tankers, an outlet 26 connected to a manifold 27 of solvent provided with an incorporated heater 28. The lower outlet 29 of the manifold 27, via a pump 30, is connected to the inlet 31 of the cooler 15 of the used solution. The system 21 for separating the components of the lower layer 19 comprises, connected in series, a pump 32, a siphon washer 33 and an evaporator 34 with an incorporated heater 35, an upper outlet 36 of the siphon washer 33, is connected by via a solvent heater 37 to the jets 4 of the cleaning chamber 1 while a lower outlet 38 is connected to the evaporator 34. An outlet 39 of the evaporator 34 is connected to the decanter 16 and a 40, to the collector 27 of the solvent.

The regeneration system 12 of the spent solution comprises the distiller 13 which comprises a heater 41 for a load 42, a refrigerator 43 and three pipes 44, 45, 46, one of which, 44, located at the bottom, is connected, by means of a pump 47, at the inlet 31 of the cooler 15. The tubing 45 is connected to the accumulator 14 of the distillate, and the tubing 46 is connected to a lower outlet 48 of the chamber 3 for rinsing the items 2 and at the upper outlet 36 of the trap 33.

The drying chamber 6 of the articles is connected to the rinsing chamber 3 and to the solvent vapor capture system 8 which comprises, connected in series with each other, a crystallizer-refrigerator 49, a siphon 50 and a filter 51. The chamber 6 and the solvent vapor capture system 8 are connected to the vacuum system 9. It is not only possible, but technologically recommended, to connect the drying chamber 6 and the solvent vapor capture system 8 together. help an air line 52.

The lower parts 53, 54, 55 of the refrigerator-crystallizer 49, the siphon 50 and the filter 51 are provided with heaters 56 and are connected to the accumulator 14 of the distillate, which, via a pencil 57, is connected to the jets 4 of the rinsing chamber 3.

According to one of the versions, shown in Figure 2, the device 23 for separating petroleum products from the upper layer 18 is constituted by a container 58 provided with a filter element 59, an unloading mechanism 60 solvent crystals and light mechanical impurities, and inlet manifolds 61 for the heterogeneous mixture, the outlet of the petroleum products 24, connected to the collector of the petroleum products 25, the outlet 26 of the solvent crystals and the mechanical impurities light, itself connected to the solvent collector 27, as well as an outlet 62 connected to the vacuum system 9.

In the version shown in FIG. 3, the separation device 23 for the petroleum products of the upper layer 18 consists of a centrifuge 63 which is provided with an inlet pipe 64 for the admission of the heterogeneous mixture, connected to the crystallizer. 48, as well as two outlet pipes 24 and 26, respectively connected to the collector of the petroleum products 25 and the solvent collector 27.

The cleaning equipment for cleaning petroleum products and mechanical impurities works as follows.

Before starting the cleaning of the items, the installation is put into operation. For that, we connect the heaters 7, 17, 37, 41 and the coolant is allowed in the cooler 15, the refrigerator-crystallizer 49 and the refrigerator 43. After reaching the required temperatures, it advances inside the chamber 1 by means of the moving means 11, the articles 2. By moving successively through the chambers 1, 3, 6, the articles 2 undergo the operation of cleaning and rinsing with the heated solvent projected by the sprinklers 4, and the ultrasonic treatment performed by the ultrasonic scures 5 to obtain hot air drying under vacuum.

By drying the surface of the articles 2, the air saturates with solvent vapors and passes into the solvent vapors capture system 8. The chambers 1, 3, 6 are sealed with respect to each other and with respect to the environment, using the valves 10.

The spent solution, consisting of a mixture of solvent, petroleum products and light and heavy mechanical impurities, passes through the cleaning chamber 1 to the cooler 15 of the regeneration system 12 of the spent solvent where it is cooled to a temperature close to that of the melting of the solvent and then the mutual solubility of the solvent and the petroleum products is reduced and an emulsion is formed; then, the emulsion passes into the decanter 16 where it settles and separates into two layers: on the one hand the upper layer 18 containing petroleum products, a small amount of solvent dissolved therein and light mechanical impurities, and on the other hand, the bottom beaker 19 containing solvent, a small amount of petroleum products dissolved therein and heavy mechanical impurities. The upper layer 18 is poured into the separation system 20 of the components of the upper layer 18 where, passing through the crystallizer 22, the solvent crystallizes at a temperature lower than that of its fusicn: then, the heterogeneous mixture formed is sent to the device 23 for separating the petroleum products where the solvent crystals and the light mechanical impurities are separated from the petroleum products liquids by filtering or centrifugation. The separated petroleum products arrive at the petroleum product collector through outlet 24 and the solvent crystals with the light mechanical impurities arrive at the collector 27 of the solvent where the solvent crystals are produced using heater 28. By the bottom outlet 29 of the collector 27, the molten solvent, using the pump 30, feeds the inlet 31 of the cooler 15 of the used solution.

The lower layer 19 is sent using the pump 32, from the decanter 16 to the system 21 for separating the components of the lower layer 19 where, in the siphon washer 33, the solvent is separated from the heavy mechanical impurities. Then, the solvent arrives at the heater 37 through the outlet 36 of the siphon washer 33, is heated to the required temperature and is sent via the injectors 4 to the chamber 1 for cleaning articles, while the mechanical impurities heavy, through the outlet 38 of the siphon scrubber 33, pass into the evaporator 34. The light impurities of the collector 27 arrive at the evaporator through the outlet 40.

In the evaporator 34, the impurities are heated by the heater 35 to a temperature higher than that of the melting of the solvent, the solvent is then evaporated and its vapors are sent through the outlet 39 to the decanter 16. The residues solid, light and heavy mechanical impurities are discharged from the evaporator 34 and used.

The solvent, after rinsing the articles, containing a small amount of petroleum precursors, passes through the lower outlet 48 of the rinsing chamber 3 to the tubing 46 of the distiller 13 and then into the charge 42. Here, by the exit upper 36 of the siphon washer brings the solvent portion free of mechanical impurities. The solvent is heated to boiling and is evaporated on the heated batch 42. The solvent vapors are condensed on the refrigerator 43 to form the distillate. Through the tubing 45, the distillate is directed to the accumulator 14 of the distillate. The distillation residue, essentially containing petroleum products and solvent, is sent, through the lower pipe 44 and through the pump 47, to the inlet 31 of the refractor 15 of the system 12 of the regeneration of the used solution.

The solvent vapor capture system 8 is connected to the drying chamber 6 of the articles, it is also recommended to supply hot air through the air line 52 for effective drying of the articles. The solvent vapors as well as the air after drying the articles pass successively through the crystallizer refrigerator 49, the siphon 50 and the filter 51, are cooled, the solvent vapors crystallize and are captured by the siphon 50 and on the filter 51. The system 8 is connected to the vacuum system 9 to create the vacuum.

The solvent crystals captured in the apparatuses 49, 5C and 51 respectively fall in the lower portions 53, 54 and 55 thereof and, as the crystals accumulate, they are melted by the heaters 56, and then are emptied by the lower parts 53, 54 and 55 into the accumulator 14 of the distillate from which the distillate is brought to injectors 4 of the rinsing chamber 3 using the pump 57.

According to one of the versions (FIG. 2), the heterogeneous mixture, consisting of liquid petroleum products, solid solvent crystals and light mechanical impurities, passes from the crystallizer 22 to the filter 59 located in the container 58 through the inlet pipe 61. Once the mixture is in the vessel 58 and using the vacuum system 9 connected to the pipe 62, a depression is created so as to separate the petroleum products.

The petroleum products reach the manifold 25 through the outlet pipe 24 and the solid residue, composed of solvent crystals and light mechanical impurities, is discharged from the filter 58 by means of the mechanism 60 through the outlet pipe 26 into the collector 27.

According to another version (FIG. 3), the heterogeneous mixture passes from the crystallizer 22 to the tubing 64 of the centrifuge 63 where the liquid petroleum products are separated from the solid solvent crystals and the mechanical impurities. The separated petroleum products arrive through the tubing 24 to the manifold 25 and the mechanical mixture is discharged through the tubing 26 into the manifold 27.

This ensures a high quality of cleaning and a reduction of environmental discharges thanks to the solvent crystallization operations on the surface of the cleaning articles, the more complete regeneration of the solvent and the separation of the impurities in closed technological circuit.

To have a more complete notion of the advantages of the invention, we refer to a concrete example application thereof.

Articles with a total area of 1 m ² , polluted by industrial oils of various uses, by metal filings and dust, are placed in the cleaning chamber where they are treated for 5 minutes by a jet of molten solvent (T 120 ° C) circulating. At the beginning of the treatment, the molten solvent which falls on the cold surface of the article crystallizes, modifies its volume, displaces the solid particles bonded to the surface of the article and thus reduces their adhesion to this surface. The treatment following the spraying with the molten solvent is a heating operation of the article which results in the melting of the solvent and the removal of impurities from the surface of the article. The solvent used is a fluorinated organic substance comprising eleven carbon atoms, having a melting temperature close to 90 ° C. and which is insoluble in the industrial oil below its melting point, while chemically inert in contact with the washed items and impurities.

The cleaned article is transferred to the rinsing chamber and is rinsed with the molten distillate of fluorinated organic substance. After rinsing, the residual pollution of the surface amounts to G, CC1 mg / cm ² . Then, the article is conveyed to the drying chamber and is dried with hot air at a temperature of 120 to 125 ° C for 5 minutes.

Solvent vapors that evaporate from the surface of the article are recovered. For this purpose, an air-vapor mixture is directed to the refrigerator-crystallizer and is cooled to a temperature of 15 to 20 ° C. Then, the vapors crystallize and settle partially on the bottom of the refrigerator-crystallizer. The formed mixture, consisting of crystals of solvent and air, is sent to the siphcn for additional extraction of the air crystals, and then to the baghouse where the complete separation of the solvent crystals and the air takes place. The filter membrane used in the filter, for example, is felt.

The solvent crystals recovered from the air-vapor mixture in the refrigerator-crystallizer, inside the siphon and in the filter, were melted and integrated with the solvent distillate.

After cleaning the article, the spent solution is regenerated in the following manner. It is cooled to the melting point. Then, the reciprocal solubility in the fluorinated solvent-industrial oil system is reduced and an industrial oil emulsion is formed in the solvent. This emulsion is decanted and two layers are then formed: the upper layer mainly containing industrial oil, solvent (2 to 3% of the mass) dissolved therein and light mechanical impurities, and the lower layer mainly containing solvent, industrial oil (0.2 to 0.3% by weight) dissolved therein and heavy mechanical impurities.

The upper layer is drained and slowly cooled to a temperature of 15 to 20 ° C. Then, the solubility of the solvent in the oil is abruptly reduced and a suspension of large solvent crystals is formed. The industrial oil suspension is filtered off. A filter is then used, the pore size of the filter membrane of which is 100 _μm . The separated industrial oil is collected in a collector while it does not contain more than 0.2% of its solvent mass. The solvent crystals are removed from the filter membrane, melted and the impurities are separated.

After cleaning the article, the solvent is returned to the spent solution, while the light impurities are directed to the evaporator and the solvent is separated therefrom. The evaporated solvent is condensed and is mixed with the spent solution, while the impurities are discharged from the evaporator and then reused.

The bottom layer of heavy mechanical impurities sent to the evaporator is separated in the scrubber, while the solvent is again used for cleaning the articles. A particular portion of solvent is distilled to obtain an industrial oil-free solvent and is then used to rinse the articles. After rinsing, the solvent is again returned to distillation. The distillation residue, which represents a mixture of 95 to 70% of the mass of industrial oil with 5 to 2C% of the solvent mass, is added to the spent solution and regenerated according to the scheme described above. The solvent, evacuated with the distillation residue, is renewed by distillation of a portion of solvent free of mechanical impurities, taken from the lower layer.

Ainsi, l'application du procédé et de l'installation pour nettoyer la surface des articles permet d'atteindre une haute efficacité de nettoyage, d'éviter les rejets de solvant et des produits pétroliers lavés dans l'environnement.The main features of the method using, for cleaning the surface of articles, the described solvent and others, are given in the table.

Thus, the application of the method and the installation for cleaning the surface of the articles makes it possible to achieve high cleaning efficiency, to avoid the release of solvent and petroleum products washed in the environment.

Industrial applicability

The invention can be used, with the greatest success in mechanical engineering, in the construction of control and measuring apparatus and in other technical fields, for cleaning articles before assembly and application of coatings. protectors.

Claims (13)

1. A method of cleaning articles comprising removing petroleum products and mechanical impurities comprising treating the surface of the articles with a circulating solvent, drying the cleaned articles, regenerating the spent solution, capturing the vapors of solvent from the air-vapor mixture and the separation of the petroleum products and mechanical impurities, characterized in that the surface treatment of the articles is carried out with the aid of the molten solvent, its crystallization taking place on the surface of the and is followed by the melting of the solvent, then the spent solution is cooled to a temperature close to that of melting of the solvent and the decantation of the cooled solution is carried out so as to form two layers: on the one hand a layer superior, containing the petroleum products, the light mechanical impurities and a part of the solvent, and on the other hand a lower layer, contained the solvent, the heavy mechanical impurities and a portion of the petroleum products, after which the upper layer is cooled until crystallization of the solvent contained therein, the petroleum products are separated therefrom, the solvent crystals are then melted and in the lower layer which is then separated the solvent, which is returned to the cleaning of the articles, while the light mechanical impurities of the upper layer and the heavy mechanical impurities of the lower layer are dried to separate the solvent which is then reused when cleaning items. 2. Method according to claim 1, characterized in that a quality of solvent such as chlorinated and / or fluorinated organic substances, solid under normal conditions, chemically inert, is used. insoluble in petroleum products and can not dissolve these at a temperature below the melting temperature of the solvent. 3. Method according to claim 1, characterized in that a part of the spent solvent is subjected to a distillation, that the distillate thus formed is sent to rinse the articles, and that after rinsing the articles, it sends again the distillate on distillation, adding the distillation residue formed during the distillation to the spent solution. 4. Method according to claim 2, characterized in that after the drying of the articles, the air and the vapors of the chlorinated and / or fluorinated organic solvent are cooled until the crystallization of the solvent is complete, and the solvent crystals are separated from the air. 5. Method according to claim 4, characterized in that melts the solvent crystals separated from the air using the molten solvent to rinse the articles. 6. Process according to claim 1, characterized in that the petroleum products are separated from the upper layer by filtration. 7. Process according to claim 1, characterized in that the petroleum products are separated from the upper layer by centrifugation. 8. Device for carrying out the method according to claim 1, comprising a chamber (1) for cleaning the articles (2), connected to a system (12) for regenerating the spent solution, comprising a distiller (13) and a storage accumulator (12). distillate (14) communicating with the latter, a chamber (3) flushing articles, connected via a pump (57) to the distillate accumulator (14), a drying chamber (6) for articles, means (11) for moving articles through the chambers (1). , 3 and 6), a vacuum system (9) and a system (8) for capturing solvent vapors, characterized in that the waste solution regeneration system (12) comprises a cooler 15) of the spent solution connected to a decanter (16) for separating the used solution into two layers: upper and lower, which is connected to a system (20) for separating the components of the upper layer (18) and to a system (21) of separating the components of the lower layer (19), the system (20) for separating the components of the upper layer (18) comprises, connected in series, a crystallizer (22) and a device (23) for separating the petroleum products an outlet (24) of which is connected to a collector (25) of the petroleum products and another outlet (26) is connected to a collector (27) of the solvent, provided with a heater (28) and having a lower outlet (29), which via a pump (30), is connected to the inlet (31) of the cooler (15) of the spent solution, and that the separation system (21) of the components of the lower layer (19) comprises, connected in series, a pump (32), a siphon scrubber (33) and an evaporator (34) with an incorporated heater (35), an upper outlet (36) of the scrubber (33) being connected via a heater (37) to the cleaning chamber (1), and a lower outlet (38) being connected to the evaporator (34), one of the outlets (39) of which is connected to the decanter (16) and another outlet (40) connected to the collector (27). ) of the solvent. 9. Device according to claim 8, characterized in that the distiller (13) is provided with three tubes (44, 45, 46), one of which (44) is connected, by means of a pump (47), at the inlet (31) of the cooler (15), another (46) is connected to the upper outlet (36) of the siphon washer (33) and to the lower outlet (48) of the chamber (3) rinsing articles (2), and the third (45) is connected to the accumulator (14) of the distillate. 10. Device according to claim 8, characterized in that the system (8) for capturing the solvent vapor is connected to the drying chamber (6) and comprises, connected in series, a refrigerator-crystallizer (49), a siphon (50) and a filter (51), themselves connected to the vacuum system (9). 11. Device according to claim 10, characterized in that the lower parts (53, 54, 55) of the refrigerator-crystallizer (49), the siphon (50) and the filter (51) are heated using a heater (56) and are connected to the distillate accumulator (14). 12. Device according to claim 8, characterized in that the device (23) for separating petroleum products from the upper layer (18) comprises a container (58) provided with a filter element (59), a mechanism (60). ) for removing solvent crystals and light mechanical impurities, and tubing (24, 26, 61, 62): inlet (61) of the heterogeneous mixture, outlet (24) of the petroleum products, outlet ( 26) solvent crystals and light mechanical impurities, and output (62) connected to the vacuum system (9). 13. Device according to claim 8, characterized in that the device (23) for separating petroleum products from the upper layer (18) consists of a centrifuge (63) provided with tubings (24, 26 and 64): inlet (64) of the heterogeneous mixture, outlet (24) petroleum products and output (26) solvent crystals and mechanical impurities.

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