Distillation chamber for extracting solvent from sludge, in particular for dry-cleaning machines

Abstract: Distillation chamber for extracting solvent from sludge, in particular for dry-cleaning machines, having a bottom (2) shaped like a half-cylinder with a horizontal axis. The bottom is provided, in a downward position, at one end, with an outlet (6) for extracting dried sludge. A shaft (4) is axially and rotatably mounted in the chamber and spatula-like sectors (17), suitable for stirring the sludge and for pushing it toward the outlet upon the rotation of the shaft, are fixed to the shaft itself.

Description: The present invention relates to a distillation chamber for extracting solvent from sludge, in particular for dry cleaning machines. As known, significant amounts of perchloroethylene are absorbed by filtration powders during the working cycle of dry-cleaning machines. The sludge to be treated also contains other residues of the washing operation, and the solvent content is such as to subject their storage and disposal to stringent statutory provisions and make them sometimes not only expensive but impossible. In order to recover the perchloroethylene from the powders, it is known to subject said powders to distillation, but the efficiency of conventional systems leaves solvent residues in the powders in amounts in the range of even more than 10%. It is also known that since at a temperature lower than 120°C the solvent does not evaporate and at temperatures above 150°C the solvent degrades, the sludge must be dried at a temperature comprised between said two values. Known from FR-A-2,584,617 is a device for regenerating solvent having a solvent reservoir, and a distillation device including a vaporization chamber and a condensation chamber arranged on opposite sides of a common wall. Means are provided for establishing a pressure difference within the vaporization chamber and condensation chamber, whereby the condensation chamber is maintained at a higher pressure than the vaporization chamber. Also known from US-A-3,169,537 is a distillation chamber for extracting solvent from sludge as defined in the preamble of claim 1. By heating the sludge to extract the perchloroethylene, sometimes the extraction temperature is reached in some regions and not in others, and a certain thickness of solid mud also stratifies on the bottom; it has been shown that it is necessary to stir the mud before and during distillation in order to operate optimally. Furthermore, when it is necessary to remove the powders and the remaining mud at the end of extraction, the operator intervenes directly, opening the distillation chamber onto the environment and subjecting himself and said environment to pollution. The interest in acting so as to reduce the perchloroethylene content to a level which allows the user of the washing apparatus to contract firms specialized in distillation waste treatment and which avoids contamination of the operators and of the environment, is evident. SUMMARY OF THE INVENTION The technical aim of the present invention is indeed to solve the above described problems, i.e. to provide a distillation chamber which allows the evaporation of the perchloroethylene from the sludge without reaching, in any point, temperatures close to the solvent degradation temperature and with no danger of pollution of any kind. Within the scope of this technical aim, an object of the present invention is to achieve said aim with a simple structure which is relatively easy to execute in practice, safe in use and effective in operation as well as relatively modest in cost. This aim and this object are achieved by a distillation chamber for extracting solvent from sludge as defined in the appended claims. Further peculiarities will become apparent and evident from the detailed description of a preferred but not exclusive embodiment of a distillation chamber according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figure 1 is a lateral sectional view, taken along a diametrical plane, of a distillation chamber according to the invention; figure 2 is a plan view of the paths of the spatula-like means in the low vertical position; figure 3 is a sectional front view, taken along a vertical plane, of the distillation chamber. With particular reference to the above figures, the reference numeral 1 generally indicates the distillation chamber according to the invention. The chamber 1 has a parallelepipedal shape in an upward region 2, has a semi-cylindrical shape with an elongated horizontal axis in a downward region 3, and is fixed to a base B. The numeral 19 indicates the heating chamber of the substance to be distilled, of the steam or diathermic-oil type. A horizontal shaft 4 is mounted axially and rotatably with respect to the chamber and is rotationally actuated in the direction of the arrow A by a motor-reduction unit assembly 5. Said chamber 1 has, at one end, in a downward position, a circular extraction outlet 6 which has sealing closure means 7 constituted by a sort of frustum-shaped plug which is coupled, in a downward position, to a vertical stem 8 which is threaded upward for vertical actuation by means of the handwheel 9 which is arranged outside the chamber 2 and is screwed to the top of the stem. Externally, the outlet 6 has a shaped lip 10 on which the mouth of a sludge collection bag 11 can be fixed, so as to form a seal, for example by means of a cord; said bag can also be of the disposable type, made of a material such as plastics. The ceiling of the chamber 1 is provided with an inlet 12 and an outlet 13 for the sludge drying air (the flow of the air is schematically indicated by white arrows) which are connected to a circuit 14 for separate drying and ventilation which allows to dry the sludge and avoid introducing into the dry-cleaning machine the unpleasant odors present in said sludge. The reference numeral 15 indicates the separator of the dry-cleaning machine, to which the distilled solvent is conveyed. Inlets can be provided in the ceiling of the chamber, and a microwave source can be connected thereto if this system is to be used to dry the sludge instead of the drying circuit 14. In this case the microwave source must be driven by sensors which detect the temperature inside the chamber to prevent an excessive temperature from leading to the degradation of the solvent. Spatula-like means 16 are fixed on the shaft 4 and are constituted by a plurality of sectors 17 (five in the example illustrated in the figures) which extend radially and are inclined and distributed with a constant pitch along the shaft so as to define a sort of interrupted scroll. The ends of the sectors 17 are provided with curved brush-like portions 18 which are suitable for scraping the bottom 3 of the chamber 1. Upon rotation of the shaft 4, the means 16 are suitable for stirring the sludge and for pushing it toward the outlet 6. The sectors define an interrupted scroll to decrease the effort for removing the dense layer which occurs at the beginning of the distillation step and to allow the reflow of the undried sludge during distillation. The operation of the distillation chamber according to the invention is evident: the rotation of the shaft 4 during the distillation steps causes, by virtue of the spatulas 16 fitted with brushes 18, the stirring of the sludge and the removal thereof from the bottom, accelerating the extraction of the solvent and preventing the reaching of the degradation temperature of said solvent. As the sludge dries, it is conveyed toward the extraction outlet 6. At the end of the drying step, the plug 7 is opened (by operating the handwheel 9) after fixing the mouth of the collection bag 11 on the shaped lip 10: by continuing to rotate the shaft 4, the brushes push the dried sludge into the bag. It is then possible to close the mouth of the bag, as in figure 3, and close the plug 7; the dried sludge will be removed from the chamber without the operator or the environment making contact therewith. It has thus been observed that the invention achieves the intended aim and objects. The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept. All the details may furthermore be replaced with other technically equivalent ones. In practice, the materials employed, as well as the shapes and dimensions, can be any according to the requirements, without thereby departing from the scope of the protection of the following claims. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Distillation chamber (1) for extracting solvent from sludge, in particular for dry-cleaning machines, comprising a semi-cylindrical bottom (3) with a horizontal axis provided, in a downward position, at one end, with an outlet (6) for extracting dried sludge, said chamber (1) being provided with an axially mounted and rotatably actuated shaft (4), and radially arranged sectors (16, 17) inclined to define an interrupted-scroll configuration and fixed to said shaft (4) for stirring sludge and pushing it toward said outlet (6) upon rotation of said shaft (4), characterized in that it comprises brushlike portions (18) connected to said sectors (17) for scraping said bottom (3) of said chamber (1), means (10) for sealingly fixing a sludge-collection bag (11) to said outlet (6), and a plug (7) engageable with said outlet (6), a threaded stem (8) connected to said plug (7), and a handwheel (9) screwed onto said stem (8) for opening said outlet (6) after having sealingly fixed a sludge-collection bag (11) thereto. Distillation chamber according to claim 1, characterized in that said radially arranged sectors (16) comprise at least five inclined sectors (16) defining a constant pitch along said shaft (4), said brush-like portions (18) being connected to the ends of said sectors (16). Distillation chamber according to claim 1, characterized in that said means (10) for sealingly fixing a sludge-collection bag (11) to said outlet (6) comprise an external lip (10) extending around said outlet (6). Distillation chamber according to claim 1, characterized in that said chamber (1) has a parallelepiped upper region (2) located opposite said semi-cylindrical bottom (3), said handwheel (9) being located externally on said upper region (2) opposite said outlet (6). Distillation chamber according to claim 1, characterized in that it comprises a drying and ventilation circuit (14) having an inlet (12) and an outlet (13) provided in the ceiling of said distillation chamber (1), and a separator (15) for distilled solvent provided on said ceiling between said inlet (12) and said outlet (13).

Inventors: ARBIZZANI TOMMASO, GHELARDINI GUALTIERO, ARBIZZANI, TOMMASO, GHELARDINI, GUALTIERO
Applicants: SODIBO SPA, SODIBO S.P.A.
Application year: 1991
Main classification: D06F43
IPC codes: D06F43, C02F11, F26B17