DYEING MACHINE AND PROCESS FOR WASHING TEXTILES IN A DYEING MACHINE

Abstract: Process for washing textile materials in a dyeing machine comprising steps in which the washing fluid is introduced into the bottom of the material treatment vessel up to a level preferably lower than that of the material to be washed, the material is then washed by circulation of the fluid and at the same time a constant quantity of clean washing fluid is added, while an identical quantity of polluted fluid is discharged so as to maintain the maximum possible concentration of pollutants in the said portion of discharged fluid throughout the entire washing period until the material has been washed to the desired degree depending on what degree of pollutant is desired in the discharge fluid. Dyeing machine incorporating a discharge device and a topping-up device that enable continuos washing operations to be carried out in accordance with said process. Its casing houses a collecting receptacle (4) positioned underneath the material carrier (2) but above the operating level of the washing fluid (15), and designed to allow recirculation of the non-evacuated washing fluid.

Description: DYEING MACHINE AND PROCESS FOR WASHING TEXTILES IN A DYEING MACHINE The present invention relates to a dyeing process and achine for washing textile materials capable of realizing large reductions in the amounts of washing fluid used and energy savings, besides reducing the time required to achieve the object of the operation. Dyeing machines, particularly those designed to contain textile materials in reels, skeins or rolls intended for dyeing, washing, bleaching or finishing operations are generally equipped with autoclaves for operating under pressure, having any shape, whether horizontal or vertical. A first known washing process involves carrying out successive operations of completely filling the vessel, e.g. an autoclave, circulating the washing fluid and emptying the vessel until the pollutants present on the aterial are removed for subsequent dilution. This process consumes large quantities of washing fluid and requires a great deal of energy and time . Another known, if antiquated, process consists in completely filling the vessel or autoclave, followed by circulating the washing fluid with the vessel full, with continuous and constant addition of a limited quantity of fluid upstream of the material while an identical quantity of polluted fluid is simultaneously tapped from the vessel at a position downstream of the material . It is an object of the invention to eliminate the problems of the known processes by drastically reducing the consumption of washing liquid, energy and process times as will be explained below with reference to the accompanying drawings in which: Figure 1 diagram-matically shows an apparatus in conformity with the principles of this invention that implements the process provided by the invention; Figure 2 is a diagram showing the curves of concentration of pollutant in the washing fluid for the two known types of washing apparatus and for the apparatus in conformity with the invention; Figure 3 diagrammatically shows an apparatus of a known type that works in accordance with the first known process cited above; and Figure 4 diagrammatically shows an apparatus of a known type that works in accordance with the second known process cited above. The two known types of dyeing machine illustrated diagrammatically in Figures 3 and 4 of the appended drawings will now be described: these are representative of the two fundamental types of dyeing machine, in whatever form they are constructed, and are equipped with the necessary devices for implementing the first and second known processes, respectively, as described above. As indicated earlier, the two known processes cited above, described below and illustrated in Figures 3 and 4 present major problems from the point of view of consumption and energy demand. The reason for this, in the first known process (see Figure 3), which involves repeated cycles of completely filling and discharging the washing liquid, is that although the efficiency (i.e. the amount of fluid necessary to achieve the object) of the washing operation is better than in the second, the abundant dilution of the pollutants by the large quantity of washing fluid present in the vessel or autoclave necessitates a long period of time to achieve that condition of equilibrium necessary to obtain maximum washing efficiency before the washing fluid is discharged through the valve 1, and before the subsequent operation of filling the vessel through the valve 2. Furthermore, the operations of filling and discharging the washing fluid have to be repeated several times in order for the final equilibrium concentration to be sufficiently low for the material itself to be regarded as washed. The repetition of these operations makes for a large consumption of fluid in order to achieve the object, besides a prolongation of the time required, as is shown by curve A in the diagram of Figure 2. In the second known process (Figure 4), the vessel, filled with fluid, undergoes, during circulation of the fluid, a continuous changing of the washing fluid by the introduction of fluid through the filling valve (2) and the simultaneous discharge of the same quantity through the continuous washing valve 1 positioned in the upper part of the vessel. Under these conditions the consumption of fluid is even higher than in the first process because of the continuous mixing of polluted fluid with the unpolluted fluid present in the vessel or autoclave. It is impossible in this situation to achieve high concentrations of pollutant in the discharged fluid, and therefore consumption and the amount of time necessary to achieve the object are further amplified, as shown by curve B of the diagram of Figure 2. In accordance with the process according to the invention the operation of washing textile materials, loaded onto a material carrier 2 and performed continuously, is carried out with a reduced level 15 of washing fluid inside a vessel 1, which may or may not be pressurized, the discharge fluid always being allowed to reach the maximum possible concentration of pollutants throughout the entire period of application of the process. The reduced quantity of fluid present in the vessel, the upper level of which remains preferably below the material to be washed, allows two results to be obtained: 1) the point of equilibrium concentration between the pollutant present in the washing fluid and that present in the material to be washed is reached much sooner (curve C) , and 2) the number of fluid/material contacts can be greatly increased owing to the large output of the main circulation pump 7 compared with the quantity of fluid m circulation, so improving the opportunities for transferring the pollutant from the material to the washing fluid. During the operation, some of the circulating fluid is taken off via the pipe 20 and the washmg- fluid discharge valve 9 and discarded. Simultaneously a control system 5 operating as a function, preferably, but not exclusively, of the level of washing fluid m the vessel or autoclave tops the vessel up with an identical quantity of washing fluid through the pipe 22 and the associated washmg-fluid supply valve 8 so that the amount of washing fluid is maintained at the constant desired level. It is also possible to provide a valve 18 to introduce compressed air m order to pressurize the vessel 1 and a valve 17 through which the washing fluid present m the vessel 1 can be rapidly and completely discharged and/or the pressuπzation air can be discharged. The process is run continuously until the desired concentration of pollutants m the material is achieved. Depending on the various different washing processes to be carried out, the efficiency of the washing operation can be further improved by fitting a collecting device underneath the material being washed m order to drain off only the most polluted phase of the circulating washing fluid. This device consists of a collecting receptacle 4 that makes it possible to evacuate the pollutant-containing fluid coming off the material before it comes into contact with the remaining fluid present at the bottom of the vessel. The said collecting receptacle 4 will m any case have an overflow for any circulating fluid m excess of the capacity of evacuation. The water can be remtroduced, if the demands of the current operation so require, through the washing valve 8 upstream, along pipe 23, or downstream of the washmg-fluid heating device 6 present inside the vessel 1 along pipe 24 depending on whether it is wished to use heated washing liquid or unheated washing liquid, respectively. The continuous process of evacuation and toppmg-up of the washing water, which is typical of the invention, permits the optional insertion of a heat recovery unit 14 to recirculate some of the heat energy present m the discharge fluid passing through the discharge pipe 21, and transfer it to the incoming washing fluid through the pipe 25, thus gaining considerable energy savings. The discharge line 21 may optionally be fitted with a suitable device 13 for measuring the level of pollutants present m the discharge flow, e.g. pH-meters, redox-meters, opacimeters, or others. When using the process described, this measuring device 13 can supply a value relating to the residual level of pollutants present m the material to be treated and therefore can be used advantageously to construct and incorporate a system that will automatically control the duration of the washing operation. Depending on the structure adopted for the apparatus that carries out the process of the invention, and depending on the specific requirements, the washing fluid can be taken directly, via the valve 12, from the water mam 26 through the meter 16 or, via a pump 11, from a special storage and preparatory receptacle 10 which has been supplied with a suitable quantity of fluid, optionally with suitable chemical additives, and is already heated to the necessary temperature for the treatment process. Practical operational tests have shown that the process carried out m accordance with the invention using the devices described permits a considerable reduction the time taken by the washing operation and m the amounts of fluid needed to accomplish the object. As curve C of Figure 2 shows, the curve of the concentration of pollutants in the process and apparatus of the invention assumes a different shape to that of the known processes. Pollutant removal is pushed towards the beginning of the operation, which means that equilibrium between pollutants present in the material to be treated is reached much sooner and the operation consumes less washing fluid.

Claims: CLAIMS 1. Process for washing textile materials m a dyeing machine, the process being characterized m that the washing fluid is introduced into the bottom of the material treatment vessel at atmospheric or superatmospheric pressure up to a level preferably lower than that of the material to be washed, the material is then washed by circulation of the fluid and at the same time a constant quantity of clean washing fluid is added, while an identical quantity of polluted fluid is simultaneously discharged so as to maintain the maximum possible concentration of pollutants m the said portion of discharged fluid throughout the entire washing period until the material has been washed to the desired degree depending on what degree of pollutant is desired m the discharge fluid. 2. Process according to Claim 1, characterized m that the most polluted phase of the circulating washing fluid is collected above the level of the washing fluid maintained m the treatment vessel, and remains separate from it, this pollutant-containing liquid being evacuated from the vessel before it comes into contact with the rest of the fluid present on the bottom of the vessel and is topped up with a corresponding quantity of new washing fluid. 3. Process according to Claims 1 and 2, characterized m that, where heated washing fluid is used, the pollutant-containing washing fluid needing to be evacuated is passed through a heat exchanger for recovery of some of its heat energy. 4. Process according to one or more of Claims 1-3, characterized m that the washing fluid may be introduced into the treatment vessel downstream or upstream of a washmg-fluid heating means. 5. Process according to one or more of Claims 1-4, characterized m that the degree of pollutants present m the discharge flow, which is useful for deciding when the washing operation can be terminated, is measured. 6. Dyeing machine characterized by the incorporation of a discharge device and a topping-up device that enable continuous washing to be carried out with the level of the washing fluid kept constant and low (15) compared with the capacity of the machine and all cases lower than the supporting surface of the material carrier (2), preferably conditions of static pressurization forming a gas cushion (17) . 7. Dyeing machine according to Claim 6, characterized m that its casing houses a collecting receptacle (4) positioned underneath the material carrier (2) but above the operating level of the washing fluid (15), this receptacle (4) communicating with a discharge device (9) and having overflows to allow recirculation of the non-evacuated washing fluid. 8. Dyeing machine according to either or both of Claims 6 and 7, characterized m that the discharge device (9) is connected to the collecting receptacle (4) or to the mam vessel (1) below the operating level (15) or to both of these components. 9. Dyeing machine according to one or more of Claims 6-8, characterized m that the washing fluid inlet device (8) is connected to the main vessel (1) either anywhere upstream of the heating device (6) or downstream of it or m both of these positions. 10. Dyeing machine according to one or more of Claims 6-9, characterized m that the flow of discharged washing fluid and that of top-up fluid are passed through a heat exchanger (14). 11. Dyeing machine according to one or more of Claims 6-10, characterized m that a measuring cell (13) is positioned on the flow of discharge fluid to supply a signal for use the automatic regulation of the duration of the washing operation. 12. Dyeing machine according to one or more of Claims 6-11, characterized m that a flowmeter is positioned on the pipe (22) relating to the flow of top-up fluid to supply a signal for use m the automatic regulation of the duration of the washing operation. 13. Dyeing machine according to one or more of Claims 6-12, characterized in that the flow of top-up fluid is taken from the water main or from a special preparatory vessel (10) via a pump (11) . 14. Dyeing machine according to one or more of Claims 6-13, characterized in that the output of the main pump (7) is varied during the washing cycle to optimize the removal of the pollutants. 15. Dyeing machine according to one or more of Claims 6-14, characterized in that a discharge connection (17) is positioned to allow rapid depressurization of the vessel by allowing the gas inside it to escape to the exterior, passing rapidly through the material as it does so. 16. Dyeing machine according to one or more of Claims 6-15, characterized in that it includes a control system connected preferably but not exclusively to the measurement of the level of the washing fluid in the vessel (1) to control the topping-up of washing fluid through the supply valve (8) of this fluid.

Inventors: POZZI ALBERTO, POZZI, ALBERTO
Applicants: POZZI ALBERTO, POZZI L MECC, COSTRUZIONI MECCANICHE LEOPOLDO POZZI S.P.A., POZZI, ALBERTO
Application year: 2000
Main classification: D06B5
IPC codes: D06B5, D06B23