FR2625914A1 - DEVICE CONSTITUTING A SOLVENT REGENERATOR - Google Patents

Abstract

The invention relates to a device which regenerates heavy solvents and particularly perchloroethylene used in dry cleaning. The device is comprised of a heating container (1), a condensor (2), containing coolig tubes (3), the assembly being covered by a cover (7), a solvent/water separator loop (4), a regenerated solvent tank (6). The boiling solvent vapours overflow from the container and are condensed on the cooling tubes before flowing into the separator loop and then into the regenerated solvent tank. The device operates at the precise boiling point of the solvent to be regenerated in order to obtain only its condensates and no other products which are mixed (such as fatty acids for the perchloroethylene which appear at 122 degrees, whereas the boiling point of the solvent is 121 degrees).

Description

The present invention relates to a device for the regeneration of non-flammable heavy solvents called solvent regenerator.

 It is applicable in particular to the field of pressing for the regeneration of perchlorethylene or PER.

 Known solvent distiller systems consist of a heating tank connected to a chimney opening into a condenser with cooling circuit by cold water or by refrigeration unit. The tank has an electrically heated or steam oil bath, which raises the temperature of the solvent until it builds up a pressure which pushes the vapors down the chimney to the condenser.

These devices are equipped with safety valves which protect against any overpressure which could occur if the chimney did not play its role. They are fitted with a hatch so that they can be cleaned after the solvent has been distilled.

 These devices are difficult to clean because of this reduced opening system, and at ground level. In addition, they do not allow good regeneration of the solvent.

 Indeed, solvents such as PER used for cleaning clothes, when soiled contain two kinds of impurities: lean dirt (earth dust), and fatty products (fats, fatty acids from perspiration on the clothes).

 The former are removed from the solvent in traditional devices, but the latter are not.

 Indeed, studies have shown that in the case of PER (whose boiling point is 12100), as long as lton maintains this product at its boiling temperature, condensates are obtained which are pure; as soon as there is no more PER and the temperature rises by one degree, condensates of an unpleasant odor are obtained which are fatty acids.

 However in traditional devices, the vapor pressure is obtained by raising the temperature of the solvent to its boiling point plus a few degrees; that is to say for the PER at around 12,500. Thus throughout the distillation the vapors are formed of PER and fatty acids and the distilled product is never pure; as it is used and successively distilled, it takes on an unpleasant odor that can be found on cleaned clothes, due to the fact that fatty acids accumulate.

 In addition, raising the temperature of the solvent above its boiling point causes chemical destabilization which constitutes acids, such as hydrochloric acid in the case of PER. These added to fatty acids then lower the pH of the solvent, make it aggressive in terms of the materials constituting the machines where it is used and cause corrosion, as well as on certain garments treated in dry cleaning.

 The device according to the invention overcomes these drawbacks to obtain a pure regenerated solvent. In addition, its design makes it very accessible for cleaning regeneration waste.

 The device constitutes a solvent regenerator comprising a heating tank, a condenser containing cooling tubes, the whole covered with a cover, a solvent / water separating lyre, and a regenerated solvent tank.

the heating tray is fully open on the top. It is fitted with a condenser outside on its upper part and all around, which has a shape of gutter fitted with a coil arranged in the bottom (or a double bottom). The condenser flows through a solvent / water separator into the regenerated solvent tank.

 Figure (I) shows the device according to the invention the solvent regenerator.

The solvent regenerator is a device for obtaining a regenerated solvent without fatty acids, it consists of - a tank (I) which contains the dirty solvent - a condenser (2) in the shape of a gutter, which contains the cooling tubes connected to the water inlet and outlet collectors (3) coming from the sector or from a cooling tower, it carries a translucent cover giving the internal lighting provided with a window to monitor
the generation. On the underside of a small side the "lyre separator (4) solvent / water connected to the two vents (5) inside - of an electrical resistance placed under the tank - of a tank (6) of regenerated solvent which is below the tank he is carrying, connected to the "lyre" to receive the clean solvent. The whole fixed on a metal frame can be put on casters for easy movement.

 In a preferred embodiment of the invention the container is cut folded welded in a stainless steel sheet 15/100 thick, it is rectangular 800x400x625 mm, folded on three angles and welded over the entire height of the fourth angle.

The bottom of the tank is attached in the form of a cover but slid upside down to close the rectangle of the tank in such a way that it leaves a 7 cm vacuum under the tank, this place serving to house the electrical resistance. The cover serving as a bottom thus placed which was previously cut folded in a sheet of stainless steel 15/100 then inserted in its housing is also welded to the edge on board of the tank. On the upper part of the tank, the solvent condenser (2) is adjusted on the external poufour, cut folded in a 15/100 sheet steel then welded. It is in the form of a gutter with a flat bottom, the height of which side adjoining the tank, welded to the edge-to-edge on the top is 7 cm, the flat bottom of I6 cm wide and the other vertical edge parallel to the first of 25 cm folded up are on the inside to form a U giving rigidity to the assembly and for subsequently receiving the cover closing blind seal. In a preferred form of the invention, placed on the bottom of the gutter at its periphery of copper tubes of 12 / 14 welded to their water intake manifold (3) are the re # idifying part. To obtain better condensation of the solvent and water vapors, these tubes are additionally arranged two one on the other, going up against the edge adjoining the tank and two others also going up on the opposite side. the other way to ensure cooling. on the flat bottom of the gutter, grouped on a short side, a condensate / water evacuation pipe (4) is welded to the sheet, two vents (5) in the corners are made using tubes welded to the sheet protruding above and below to be connected to the "lyre" (4) of solvent / water separation.

 The whole is closed by a cover, only the small side of the gutter where the vents are located, the evacuation pipe, the water collectors, is closed by a plate (7 of plastic cut and screwed from which only the the water inlet and outlet protrude. The cover is made of a translucent plastic material, its shape is rectangular, the top rounded in the direction of the width and over the entire length,. in its center a glass of 50 x 30 cm allows internal visibility, the U-shaped periphery which comes to be embedded on the edge of the gutter where it rests Finally, all the hot surfaces are lined with a glued insulating material.

 Two stainless steel square electric shielded plates of 39 cm side thickness 6 cm power 4000 watts are placed under the tank and ensure the temperature rise. The capacity of the tank is 200 liters, but the filling must be done to a maximum of 150 liters so as not to have an overflow because of the dilatation of the solvent during the rise in temperature.

The consumption for regeneration is around 20 Xwa, that is to say very reduced compared to traditional devices: this is due to the fact that the dead weight is very low since there are no more oil bath and double walls to be heated, and that the tank is made of a thinner sheet (15/100) since there is no longer any imperative to resist
at a pressure. The consumption of cooling water can be zero If a water cooling tower is coupled.

The regenerated solvent tank is mounted on a frame made of welded cut steel angle and supported by four casters, it serves as a support for the heating tank. The tank is executed in a 3 mm aluminum sheet cut folded welded, it is connected to the "lyre" forming water / solvent separator and has in its lower part a valve for evacuation of the regenerated solvent, its size is 100x75x25 cm.

 The lyre ", or water / solvent separator, consists of a 27/30 mm stainless steel tube called" lyre "here because of its shape.

The U-shaped tube has three openings, two on one leg, one on the other. On the side with two openings, the highest is the water outlet (8), the lowest in the middle of the leg the solvent / water inlet (9) which is connected to the drain pipe of the gutter just above by a flexible plastic pipe; on the other leg, the opening is made just halfway up opposite the two solvent inlet / water outlet openings, this single opening on one side is the outlet (10) pure solvent which is connected to the regenerated tank located below. The two tips of the
U are both connected to the gutter vents by a flexible plastic pipe.

 In another more elaborate embodiment of the invention, lton can add a solenoid valve (11) to the outlet of the drain pipe of the gutter which cuts the circuit going to the "lyre" and to the regenerated tank. to send it in a small container intended to receive fatty acids; which could appear and condense in the gutter (in small quantity) between the moment of cutting of the heat source and its cooling. This solenoid valve can be controlled by the same device that cuts the power supply.

 The apparatus described here is therefore intended to regenerate heavy non-flammable solvents and in particular perchlorethylene used in the field of dry cleaning.

 In the embodiment according to Figure (1) the solvent is located in the tank (1) heated by the electrical resistance which is placed below. the liquid brought to the boil evaporates and its heavy vapors will overflow from the tank to condense on the cooling tubes in which cold water (3) circulates inside the condenser (2). The condensates returned to the liquid state will flow into the "lyre" separator solvent / water (4).

The water is evacuated by the water outlet (8) and the pure solvent by the solvent dump (10) before flowing into the tank (6) of regenerated solvent. The end of the regeneration will be carried out either manually by the user who, when he sees the appearance of the vapors, will cut the power supply; either automatically by a device which will detect a temperature rise by means of a probe and cut off the power supply. With in both cases, the possibility of using a solenoid valve which will divert any fatty acid condensates which may appear between the moment of cut-off of the electrical supply and the cooling of the resistance from the regenerated solvent circuit.

 The dimensions of the regenerator can be changed to modify the capacity so as to adapt the device to the needs of each user.

 The operation is carried out by boiling the solvent without pressure: the solvent is in the tank which is heated from below by means of an electrical resistance. The temperature gradually rises to the boiling point of the solvent (121 o C for iron). Vapors are formed above the surface of the liquid which will rise and overflow from the heating tank. This one is equipped outside on its upper part and all around a gutter where is arranged a coil inside which circulates cold water. The vapors which overflow from the heating tank will invade the gutter and condense on the cold coil. The gutter is pierced on one of its sides so as to drain the regenerated product in a system of tubes or "lyre" which allows to separate by difference densities of the heavy solvent, water that may be in the contaminated solvent and water that has condensed due to the humidity of the ambient air.

 Thus, as long as there is solvent in the tank, the regeneration will take place, until we will see that the vapors which were colorless will start to take the form of a white mist. 04 finds by means of a temperature probe that the boiling point of 1210 C goes to 1220 C then 1230 C, etc. if the heat source is not stopped.

 It is at this very precise moment that the electrical resistance must be stopped so as to leave lean dirt and especially fatty acids at the bottom of the heating tank. In this way, a regenerated solvent which is pure is obtained.

 The cut-off point of the heating system can be achieved manually, i.e. by monitoring the color of the vapors, since it is possible to determine precisely that for a fixed quantity of solvent, it will take an invariable time of regeneration before seeing vapors of another color appear (for example, for a quantity of 150 liters, with an electric power of 8000 watts, it will take an hour to reach a boil and another two hours for the end point solvent evaporation before fatty acids) or the cut can be done automatically by a device that will cut the power to the heating resistor as soon as the temperature inside the tank exceeds the point by one degree solvent boiling.

The present invention makes it possible to recover and condense the solvent vapors without putting them under pressure, that is to say only at the boiling point of the product, and thus to separate in two stages the production of iron vapor and of acids. fatty, which is impossible in traditional appliances which need a pressure to push the vapors into a chimney odor and thus operate at a temperature above the boiling point resulting
PER plus fatty acids throughout the cycle.

Claims (10)

1- Device constituting a solvent regenerator intended to regenerate heavy non-flammable solvents and in particular parchlorethylene used in dry cleaning, comprising a heating tank (I), a condenser (2) containing cooling tubes (3), the whole covered with a cover, with a separator (4) solvent / water separator (4), with a regenerated solvent tank (6) characterized in that the heating tank is equipped with a gutter fitted with a coil forming the condenser. 2- Device according to the preceding claim characterized in that the heating tank is fully open on top so as to allow evaporation of the solvent over its entire surface. 3- Device according to the preceding claims characterized in that the condenser is located outside of the heating tank, on its upper part, and all around. 4- Device according to the preceding claim characterized in that the condenser occupies a position which allows to bring the vapors therein without exerting pressure on them, that is to say at the boiling point of the solvent to be regenerated , and thus to have only condensates of the regenerated product and not of other products having a slightly higher boiling point. 5- Device according to claims3 and 4 above characterized in that the condenser has the shape of a gutter which allows the regenerated solvent to flow to the separator. 6- Device according to the preceding claim characterized in that the gutter is arranged with a coil disposed in the bottom or in that the gutter has a double bottom for circulating cold water intended to condense the vapors. 7- Device according to claim I characterized in that the solvent / water separator is a U-shaped tube with three openings, two on one leg, one on the other, in that on the side with two highest openings is the water outlet, the lowest in the middle of the leg the solvent / water inlet, and in that on the other leg, the opening at half height with respect to the two openings of the first, is the pure solvent outlet. 8- Device according to the preceding claim characterized in that the two ends of the legs of the U forming the separator are connected to the interior of the regenerator and serve as vents, so as not to create an air vacuum when the solvent s flows into the regenerated tank.  9- Device according to claim I characterized in that it comprises a temperature control apparatus intended to stop the electrical resistance as soon as the regeneration of the solvent is complete, and before obtaining condensates of different nature, - thus leaving the solvent its original purity. 10- Device according to claims 5 and 7 characterized in that it comprises a solenoid valve at the outlet of the drain pipe of the gutter, controlled by the temperature control apparatus, which cuts the circuit going to the lyre separator to send it to a container intended to receive condensates of a different nature from the solvent, which could appear between the moment of switching off the heat source and its cooling.