US3104936A - Process for the chemical cleaning of textiles - Google Patents

Description

Sept. 24, 1963 H. FUHRING PROCESS FOR THE CHEMICAL CLEANING OF TEXTILES 2 Sheets-Sheet 1 Filed Feb. 3, 1960 INVENTOR. f E/A/k/CI/ Farm/1V6 19 7' TOR IVEfS United States Patent 3,194,936 PRGCEdS FER TEE CHEME CAL CLEANH l G 0F TEXTHLES Heinrich Fiihring, Augsburg, Qermany, assignor to Boehler and Ferdinand Weber, trading as the firm llochler Weber Kommanditgesellsehait, Augsburg, Germany Filed Feb. 3, 1966, Ser. No. 6,529

Claims priority, application Germany Feb. 6, 1959 3 tllaims. (Cl. 8-142) The invention concerns a process for the chemical cleaning of textiles.

An object of the invention is to reduce the consumption of solvent and to shorten the time required for its recovery in chemical cleaning machines.

In the operation of conventional discharge systems it is found that during the first half of a recovery period, i.e. half the time which is required for the condensation of the total amount of solvent, about 80% of the solvent is recovered Whilst only about 20% can be recovered during the second half period. From this it is evident that the operation of the recovery device of a known chemical cleaning apparatus is very uneconomical in the second half period of the total recovery time.

It was previously customary in solvent recovery to suck out the solvent-air mixture contained in the drum and to lead it over a cooler in which a portion of the aspirated mixture could condense whereupon the uncondensed vapors are heated and introduced afresh into the drum. In this case it has been shown that approximately in the first third of the recovery time the maximum solvent proportion, for example 80%, is recovered. The condensed water-solvent mixture arrives from the cooler to a water separator for separation of the water from the solvent. Furthermore it has been shown that the still uncondenscd portions of the solvent, thus for example 20%, could be recovered subsequently only slowly and tediously. The time required for the recovery of this remainder has a very unfavorable bearing on an economic work expenditure of the whole cleaning machine. It therefore, for example, 80% of the solvent is obtained within the first third of the recovery time the recovery of the remaining proportion of, for example, 20% needs more than twice the initially mentioned recovery time. In accordance with the invention it was recognized that it is advantageous to abandon the recovery of the circulating solvent, once the maximum proportion economically recoverable in this way has been extracted, andthat the not inconsiderable solvent remainder shouldbe recovered in other ways with the object of substantially shortening the total recovery time.

er and above this it has been found that there are further noticeable disadvantages in the customary considerable heating of the air-solvent mixture. On condensation of this heated mixture a large amount of work of condensation is performed. Moreover, the textile fibers sufier, as a result of the heat which is introduced, an unfavorable action which makes them straw-like or felted, hence it is worth trying to use the lowest temperature possible in chemical cleaning of textiles. This aim was previously difficult or indeed impossible to achieve by reason of the unavoidable prolongation'of the recovery time.

According to the present in 'ention, a process for the recovery of solvent used for the chemical cleaning of textiles includes the steps of cooling the solvent accruing to a considerable extent in a first condensation phase, interrupting the main solvent-recovery operation, and passing a solvent residue with fresh air admixture through active carbon during a subsequent cleaning phase and main solvent-recovery phase.

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The air-solvent mixture, present in a drum which is adapted to receive the textiles to be cleaned, may be sucked out by a strong vacuum and is led over a cooler system whence the vapors not condensed in the cooler are led to the active carbon in which the solvent-residue components are stored, and if necessary recovered, during the subsequent working phase of the system. The air mixture, after leaving the cooler, may be led over a heater after formation of the vacuum, whereupon the operation is interrupted and the cleaning drum is flushed with fresh air. The amount of fresh air admitted may be continuously increased after completion of the main recovery operation.

The vacuum may be produced in the drum at the com mencement of the solvent-recovery phase by means of a separate high-vacuum pump.

Lightly heated recoverable condensate in the cooling system may be subjected to a line sprayin An apparatus suitable for use in the chemical cleaning of textiles and for the recovery of solvent, by a process including, a circulatory system comprising an air-admission duct, a drum, a suction duct, a vacuum pump and a cooler all forming part of a solvent-residue-recovery system additionally comprising an adsorber with a charge of active carbon and at least one control member which is adapted to switch the adsorber' into and out of the solvent-residue-recovery system. This can for example be a closed cooling system using honeycomb-plate or tube coolers; alternatively an open cooling system using spraying nozzles may also be suitable and in fact specially advantageous.

The control member may be a duct-closure means in the form of a ilap valve which in one terminal position is adapted to close a communication duct arranged between the cooler and the adsorber and in the other terminal position is adapted to close a communication duct disposed between the cooler and air-inlet duct of the drum. The control member may be used in the forma tion of the vacuum, the control of the circulation as well as the regulation of the fresh-air admission by complete or partial closing of the drum inlet.

A wholly or partially closable fresh-air connection diict may be disposed in the region of the control member and adapted to discharge air into the drum inlet, an air heater may additionally be provided between the air connection duct and the drum.

The adsorber may be constructed as a single-charge device and may be connected to a waste-gas duct closable by means of a flap valve.

The adsorber may have an individual cooler connected between it and the drum. The adsorber may further be connected, by Way of a communication duct, to a Water separator of the cleaning machine. V

A spray device may be disposed in a front chamber of the cooler which latter may be provided with internal bafiles.

The adsorber may include twin active-carbon beds which can be switched alternately to solvent reception and to regeneration.

An infrared-ray device, the rays of which are advantageously adjustable in the direction of the drum, may be arranged in the air-admission duct. A very fine spraying device may be connected in front of the cooling system to irrigate the aspirated mixture with fine droplets and help dissipate the heat present in the mixture.

The invention will he described further, by way of example, with reference to the. accompanying drawing, in which:

FIG. 1 is a schematic side elevation of a chemical cleaning installation incorporating a spray device;

FIG. 2 is a schematic side elevation of an adsorber with twin active-carbon beds;

FIG. 3 is a variant of the cleaning installation shown in FIG. 1, utilizing a closed cooler system and a separate high-vacuum pump; and- FIG. 4 is a work diagram illustrating the recoverable amount of solvent for each unit of time.

In FIG. 1 there is shown, purely schematically, a drum 1 having a loading door 2 and a sight glass 3 for checking the liquor level. Drivingmotors 4 and 5 (for Washing and centrifuging) are likewise illustrated only schematically. The apparatus serving for the solvent recovery comprises a suction duct 6 having a liquid interceptor 7' disposed therein, a multistage vacuum pump 8 with driving motor 9 and acooler 12 connected thereto.

Anair admission duct 28, which discharges into the drum 1, is connected with thecooler 12 and has aheater 11 disposed therein. Bafiles orpartitions 27 are provided within thecooler 12 which act to condense the air-solvent mixture. Aspray device 25, provided in the front chamber 12' of thecooler 12, irrigates the mixture leaving the vacuum pump 8 with water in a process known as open cooling.

At one end of thecooler 12 there is disposed acontrol member 15 which, in its dotted-line upper position, closes a waste-gas duct 29 and in its lower position 15' closes aninlet 32 of the air-admission duct 28. Adischarge duct 31 extending upwardly is connected to the waste-gas duct 29 and is closable by means of afurther control member 18 in its position 13'.

In this position of the control member, the vapors flowing through the waste-gas duct 29 can pass to an active-carbon bed 19 of anadsorber 17 which is advantageously preceded by acooler 23. Anexchange duct 33 of theadsorber 17 is cap-able of being closed by means of a flap valve 29. Acondensate drain 22 leads from thecooler 23 of theadsorber 17, or from any desired point of this adsorber, to awater separator 14 which is connected through a communication duct 13- to themain cooler 12 of the cleaning plant.

An air-admission duct 39 discharges into thedrum inlet 28 in the region of thecontrol member 15. Theairadmission duct 30 can be closed or opened by means of aclosure valve 16. V

The operation of the cleaning plant according to the embodiment shown in FIG. 1 takes place in the following manner:

=At the commencement of the solvent-recovery process it is recommended that thecontrol member 15 be set in theposition 15 and the air-admission duct 3% closed by means of theflap valve 16. The vacuum pump 8 now draws the air-solvent mixture out of the drum 1 through the suction duct 6 wherein any fibers, flue or similar solid I components which might be present are held back by thefilter 7. As a result of theduct 28 being closed, a vacuum is formed in the drum 1. The aspirated mixture arrives in thefront chamber 12 of thecooler 12 in which the mixture is sprayed with Water by means of thespray device 25. In this way the added water droplets are finely distributed on the solvent and a supercooling of the mix ture occurs which promotes its condensation on thepartitions 27. In this way a considerable part of the. aspirated mixture is precipitated, the condensate passing through theduct 13 to the water separator'l-d. The noncondensed mixture arrives in theadsorber 17; thereupon thecontrol member 15 can be set in a middle position, whereby circulation of the uncondensed mixture takes place, since a part of this mixture can be re-circulated to the drum through the inlet duct '28 and theheater 11.

The more the flap valve is brought into theposition 15 the more extensive is the circulation and the stronger is the drum heated if theheater 11 is operated. In order to stopthe recirculation theflap valve 15 is brought into theposition 15 and the non-condensed mixture led through the waste-gas duct 29 into theadsorber 17 whoseflap valve 13 is in theposition 18. In this receiving phase the air-admission duct 3t is still completely or nearly closed. A strong vacuum therefore exists in the drum 1. If aseparate cooler 23 is connected in front of theadsorber 17, condensation of the mixture led through the Waste-gas duct 29 can take place afresh therein. The condensate flows through thedrain 22 to thewater separator 14 or thecommunication duct 13. The remainder of the solvent-air mixture, which is still uncondensed, is then led' into the bed ofactive carbon 19 wherein the solvent components are retained. The released air passes through theconnection 33 to the atmosphere.

Now thethrottle flap valve 16 in the air-admission duct 30 is opened so that fresh air can flow into the drum 1. This fresh air can be gently heated in theheater 11.

In this way the complete drying out of the textile goodsin the drum 1 as a result of the vacuum is avoided and, in addition, turbulence of the solvent present in the drum 1 is efiected. In previously known cleaning plants. a considerable running time is required in order to carry out a solvent degassing in the drum 1; in the system here described owing to a wider opening of the air-admission duct 31}, all gas residues are driven out of the drum within the shortest time possible and are either condensed in the cooler 12 or led into the active-carbon bed 19 ofadsorber 17.

Instead of the single-charge adsorber 17 shown in FIG. 1, it is also possible to provide an active-carbon plant, known per se, into which are led the non-condensed solvent residues recovered from several charges, for example from a days working. This adsorber can then be regenerated during the night or during pauses in the work. In the use of this larger active-carbon plant, however, a larger starting quantity of solvent is needed since, during the time of its operation, not inconsiderable portions remain in the active carbon from the preceding operation. I

As shown in FIG. 2 it is also possible to replace theadsorber 17 shown in FIG. 1 by a twin plant of which each unit 1-7, 17' can be switched alternatively to solvent reception and to regeneration. This control is effected by theclosure flap valves 18 and 18 in combination with a flap valve 24 in an exhaust flue for the waste gases.

Adsorber 17, 17 may also be provided withsteamadmission connections 21, shown in FIG. 1, through which steam is led in for the regeneration of theactive carbon 19.

FIG. 3 shows-a variant of the cleaning plant shown in FIG. 1 wherein, instead of the spray nozzle cooling 25, a so-called closed cooling is efiected by a cooler 10. Such closed-cooling systems are known so that a detailed description is not necessary. For the rest it should be noted that the function of the cleaning plant shown in FIG. 3 is similar to that shown in FIG. 1.

In the embodiment shown in FIG. 3 aseparate highvacuum pump 34 sucks up the solvent-air mixture through thesuction duct 33, which is closable by means i of aclosure member 37, and feeds it by Way of an ad'-mission duct 35 into the cooler 12. The purpose of this high-vacuum pump 34- is to provide, in the first instance, a vacuum in the drum 1 when thecontrol member 15 is disposed in theposition 15 and the air-admission duct 30 is closed at the commencement of the recovery oper-' ation; thus no air can arrive in the drum inlet 28.- The aspirated mixture is then for the greater part condensed in the cooler, 1d, e.g. in the manner shown in FIG. 1, bya'spray nozzle 25 or by similar cooling means, whereupon the non-condensed portion of the mixture can enter theadsorber 17 by way of the waste-gas duct 29. As soon as the desired vacuum has been obtainedin the drum 1 the high-vacuum pump 34 is cut off and a onestage vacuum pump 8' is put into operation. In this case, either by opening the control member 15 a recirculation can be obtained, or, with thecontrol member 15 closed, fresh air can be led into thedrum inlet 23.

As soon as the maximum of solvent has been recovered in each case, fresh air is introduced into the drum 1 and the residual solvent, blown out of the drum 1, is condensed by means of :the cooler or led into theactivecarbon bed 19 ofadsorber 17. In this case the control member assumes the position 15'.

In FIG. 4 there is illustrated a diagram showing the relationship between recoverable amounts of solvent and recovery time. In this case, starting for example from a total recovery time of minutes, it is evident that in about 4 minutes of recovery time the bulk of the recoverable quantity of solvent has already been retrieved. With advancing recovery time the recoverable quantity of solvent drops. In order that a tolerable loss exists in the recovery of the solvent it has previously been necessary to use the whole recovery time of 20 minutes from which it can be seen that approximately in the time range between 9 and 20 minutes only a slight recovery takes place. This uneconomical recovery time represents a loss of Working time of the total cleaning procedure.

In contradistinction the invention utilizes merely the optimal recovery period, approximately in the time interval of O to about 9 minutes, so that the residual recovery time up to 20 minutes is saved since, in consequence of the intensive scavenging of the drum 1 by means of fresh air, an intensive and sudden emptying of the drum occurs while the still recoverable quantities of solvent are fed into the active carbon. Although this quantity of solvent is lost to the working cycle actually in progress, it can be immediately recovered again on the next cycle. This illustration underlines the significance of the present invention with the help of which it is possible to operate with substantially shorter total Working times since it is no longer necessary to recover the Whole recoverable solvent in the circulatory system.

It is, for example, possible to provide an infrared radiation device instead of theair heater 11 shown in FIGS. 1 or 3. This device could exhibit a variety of features. If thevalve 15 is disposed in theposition 15 the fresh air introduced through the duct can be heated. If theflap valve 15 is in the dotted position or intermediate position then the mixture led into circulation can likewise be heated by means of the infrared radiator. Finally there is the very advantageous possibility of heating the drum charge by direct radiation when theflap valve 15 is closed and the air duct is closed during the formation of the vacuum, in order in this manner to accelerate the vaporizing operation in the drum.

Another advantageous feature of the invention consists in providing the aforementioned fine spraying device 3 8 of FIG. 3 in front of the closed cooler system, with the help of which finest mist droplets are sprayed into the mixture sucked in by the blower 8' or 8. In this case an intensive vaporization of the sprayed mist is effected whereby heat is withdrawn from the induced mixture and condensation is brought about. By means of this pr condensation with the help of a fine spraying device, the degree of etliciency of the closedcooler system 10 is increased and, moreover, a favorable humidity is obtained in the air. Over and above this there is the result that water from the condenser is returned to the spray device and a closed circulation of spray Water is obtained with noticeable economy.

I claim:

l. A process for recovering solvent from a dry-cleaning pl ant during a drying phase of a working cycle in which textiles treated with solvent in a drum during a preceding washing phase are dried by an air stream circulating through the drum, comprising the steps of aspirating solvent-laden air from said drum, recirculating the aspirated air through said drum in a substantially closed circuit, extracting solvent from the circulating air by cooling the latter before returning it to said drum, so proceeding for a period sufficient to recover more than half the original quantity of solvent until the rate of solvent recovery declines substantially from a peak value, and thereupon removing the remaining solvent from the drum at an accelerated rate by flushing said drum with fresh air and conducting the flushing air with its entrained solvent from the drum through an adsorber for said solvent.

2. A process as defined in claim 1 wherein the flushing air is cooled just before entering said adsorber.

3. A process as defined in claim 1 wherein the adsorber is regenerated during the working cycle.

References Cited in the file of this patent UNITED STATES PATENTS 1,669,235 Fenton May 8, 1928 1,775,699 Silver Sept. 16, 1930 2,009,365 Wait July 23, 1935 2,072,332 Hatfield Mar. 2, 1937 2,660,869 McDonald Dec. 1, 1953 2,836,045 Smith May 27, 1958 2,845,786 Chrisman Aug. 5, 1958 Washing phase of a subsequent

Claims (1)

1. A PROCESS FOR RECOVERING SOLVENT FROM A DRY-CLEANING PLANT DURING A DRYING PHASE OF A WORKING CYCLE IN WHICH TEXTILE TREATED WITH SOLVENT IN A DRUM DURING A PRECEDING WASHING PHASE ARE DRIED BY AN AIR STREAM CIRCULATING THROUGH THE DRUM, COMPRISING THE STEPS OF ASPIRATING SOLVENT-LADEN AIR FROM SAID DRUM, RECIRCULATING THE ASPIRATED AIR THROUGH SAID DRUM IN A SUBSTANTIALLY CLOSED CIRCUIT, EXTRACTING SOLVENT FROM THE CIRCULATING AIR BY COOLING THE LATTER BEFORE RETURNING IT TO SAID DRUM, SO PROCEEDING FOR A PERIOD SUFFICIENT TO RECOVER MORE THAN HALF THE ORIGINAL QUANTITY OF SOLVENT UNTIL THE RATE OF SOLVENT RECOVERY DECLINES SUBSTANTIALLY FROM A PEAK VALUE, AND THEREUPON REMOVING THE REMAINING SOLVENT FROM THE DRUM AT AN ACCELERATED RATE BY FLUSHING SAID DRUM WITH FRESH AIR AND CONDUCTING THE FLUSHING AIR WITH ITS ENTRAINED SOLVENT FROM THE DRUM THROUGH AN ADSORBER FOR SAID SOLVENT.

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