US3145555A

US3145555A - Closed apparatus for the wet treatment and particularly dyeing of textiles with liquor heated to above 100 u deg. c.

Info

Publication number: US3145555A
Application number: US60752A
Authority: US
Inventors: Krantz Hubert
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-07-24
Filing date: 1960-10-05
Publication date: 1964-08-25
Anticipated expiration: 1981-08-25

Description

CLOSED APPARATUS FOR THE WET TREATMENT AND PARTICULARLY DYEING OF TEXTILES WITH LIQUOR HEATED TO ABOVE 100C Filed Oct. 5, 1960 NNN/W/W/WW/WW/W/W/Q ATTORNEY United States Patent 3,145,555 CLQSE AKPARATUS FOR THE WET TREATMENT AND PARTEEJULARLY DYEING @F TEXTILES WITH LEQUUR HEATED TQ ABOVE C. Hubert Krantz, Pestschliessfach 83f), Aachen, Germany Filed 0st. 5, 196%, Ser. No. 69,752 1% Claims. (QR. 68-489) The present invention relates to a wet treatment of textiles, and it particularly relates to an apparatus for a closed system for Wet treatment of textiles.

The present invention will be particularly described in its application to the dyeing of textile material in various forms, such as in the form of loose fibers, cross spools, cakes and the like in which the material is treated at a temperature above 100 C.

It is to be understood however that it has broader application to Wet treatments of various types of textile materials.

It is among the primary objects of the present invention to provide a shorter duration of the dyeing process, a better absorption of the dye and a greater uniformity with printing color applications.

It is also a further primary object of the present invention to dye various fibers of different chemical constitutions such as, wool, cotton, cellulose or synthetic fibers to the same shades particularly at high temperatures above 100 C.

In high temperature dyeing, the elevated pressure required to prevent excessive evaporation of the dye bath is achieved by either a pressure pump in addition to the stirring pump for the dye bath or a receptacle system is provided to take care of the increase in volume when the bath is heated. In the latter instance, normally there will be an elastic pressure cushion positioned above the bath which will create a pressure action against boiling and evaporation of the bath.

These closed expansion receptacles with the necessary additional space providing for a pressure cushion render the dyeing apparatus expensive, and they make it difficult to add additional dye liquor. This is particularly so where the expansion receptacle or a receptacle prow'ding the additional space is used for the addition of the dyes and where the dyes are introduced in one receptacle and then subsequently transferred into the circulating dye bath.

It has not been found readily possible to feed the dye into the circulating dye bath from a separate additional container or with the aid of an additional pump. Nor has it been found satisfactory to generate the necessary pressure applied to the circulating dye bath with an ad ditional pump which will also take care of the addition of the dye material. This latter expedient does not perrnit dispensing with the enclosed expansion container having the elastic cushion.

Furthermore, the continuous feed of liquor into the bath circuit which is necessary to maintain the desired pressure also renders necessary the withdrawal of a quantity of the hot dye liquor corresponding to the introduction of the cold dye liquor with loss of heat and decreased efficiency.

It is among the objects of the present invention to provide a novel high temperature dyeing system which Will be much more effective and efilcient in respect to heat consumption and which will provide a more efficient overdl apparatus and procedure.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is given by way of illustration and explanation only and not by Way of limitation, since various changes therein 3,145,555 Patented Aug. 25, 1964 may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accomplishing the above objects, it has been found most satisfactory according to a preferred embodiment of the present invention to provide an additional pump for the generation of pressure in a high temperature dyeing system.

In the preferred system according to the present invention, the discharge of a heated dye liquor from the circulating dye bath is restricted to the time and period during which the additional dye material is added or injected by a pump into the dye bath circuit. At the same time a corresponding amount of dye liquor is removed from the main bath circuit.

During the remainder of the dyeing operation, the feed of cold liquor into the main bath circuit, and the corresponding Withdrawal of heated liquor from the main bath circuit is discontinued.

In the preferred procedure according to the present invention, the saving of heat is achieved in the closed high temperature dyeing apparatus by providing an auxiliary pump for generating the excess pressure and for introducing dye and chemical additives into the circuit of the circulating pump.

This is achieved when no dye or additional dye liquor is being added, and when the auxiliary pump conveys the dye bath liquor from the auxiliary receptacle through a short circuit conduit with an overflow valve directing back into the auxiliary receptacle.

When this occurs, the opening pressure of the overflow valve in the short circuit conduit acts by way of a branch conduit to the treatment receptacle to apply pressure on the liquor circuit in the treatment receptacle.

To reduce the number of circuits, it is preferable that the conduit branching from the short circuit conduit to the treatment receptacle simultaneously form a discharge conduit through which an amount of liquor is discharged which corresponds to the additional amount of liquor added during the addition of the dye materials into the circulating dye bath.

This discharge conduit will accommodate the increase in volume as a result of heat expansion during the heating of the dye liquor as well as the additional amount of volume due to the addition of dye liquor which should be offset by the amount of liquor discharged from the treatment receptacle into the auxiliary receptacle.

So that the liquor discharging from the treatment receptacle will not lead to vapor formation in the open auxiliary receptacle, the discharge conduit is provided with a cooling jacket.

With the foregoing and other objects in view, the invention consists of the novel construction, combination and arrangement of parts as hereinafter more specifically described and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications can be resorted to which fall within the scope of the claims hereunto appended.

In the drawings wherein like reference characters denote corresponding parts throughout the several views:

The figure shows a schematic layout of the closed dyeing apparatus according to the present invention.

Referring to the drawing, there is shown an enclosed main processing vessel or container 1. The dye liquor in the vessel 1 is circulated by a propeller pump 3 which is driven by the reversible motor 2. This propeller pump 3 will remove liquor from the vessel 1 by the conduit 4 and feed it back by the conduit 5.

Depending upon the direction of flow and the direc tion of rotataion of the propeller 3, the dye liquor may be forced from the inside to the outside of the spools 6 which may be mounted in a complete system of ver- 35. tical groups upon the carrier '7 inserted in the vessel or container 1.

Adjacent the propeller pump 3 and between the feed and discharge conduits 4 and 5, there is provided a pressure conduit 8 associated with an auxiliary pump 9.

The auxiliary pump 9 has a suction or conduit 1% which is connected to the underside of the open auxiliary vessel 11.

This auxiliary vessel 11 may serve simultaneously as an expansion or starting vessel.

In the line 3, there is provided a check valve 12 as Well as a three Way valve 33.

The check valve 12 will prevent return tlow of dye liquor from the container 1 into the auxiliary vessel 11 in the event that the auxiliary pump should break down or become ineffective.

The three way valve 13 may be positioned so that liquor drawn oil by the auxiliary pump 9 from the vessel 11 is forced into the circulating circuit of dye liquor through the lines 4 and 5 which passes through the treatment vessel 1.

This will occur when the valve 13 is in the position shown in the figure.

Alternatively, the valve 13 may be set to return liquor to the auxiliary vessel 11 by way of the short circuit conduit 14 from the pump 9.

This short circuit conduit 14 is provided at its upper end with an overflow valve 15 which is connected by the conduit 16 to the auxiliary vessel 51.

To provide that the pressure should be applied to the treating bath in the vessel 1 when the pump 9 is disconnected from the circulating liquors in the conduits 4 and 5, an auxiliary conduit 17 is provided.

This conduit 17 leads to the treating vessel 1 at one end and connects with the short circuit conduit at the other end in advance of the overflow valve id.

The opening pressure of the overflow valve 15 is adjusted to a valve which is independent of the direction of rotation of the treating bath which at all times will assure an elevated pressure in the main vessel 1, and in the conduits 4 and 5, will be suflicient to prevent boiling and evaporation ofthe dye bath.

The conduit 17 leading from the short circuit conduit 14 to the treating container 1 simultaneously forms the discharge conduit for the amount of liquor which is discharged from the vessel 1 during the heating of the bath. This will take care of the increase in volume resulting during the heating of the bath and will also take care of the amount of liquor which is added to the bath during the processing.

Thus the conduit 17 serves to take care of discharging excessive volume from the vessel 1 either because of increase of volume upon heating or because of introduction of additional liquor into the dye bath circuit.

In order to prevent the hot discharge liquor which will flow into the vessel ll from causing boiling and evaporation of the content of the vessel ll, a cooling jacket 15 is utilized to cool the flow from the vessel 1 to the vessel 11.

The short circuit conduit 14 also has the advantage of avoiding addition of dye liquor to the circuit through the conduits 4 and 5 when no dye is to be added, and the pump 9 will then circulate the liquor back into the vessel 11 and at the same time no liquor will be passed into the vessel 11 from the upper part of the vessel 1 through the conduit 17.

This arrangement will save the heat of the liquor in the vessel 1 inasmuch as discharge from the vessel 1 into the vessel 11 will only take place when additional liquor is being added from the pump 5 and through the conduit 8 into the circuit of the conduits d and 5.

When no liquor will flow through the conduit 1'7 from the vessel 1 to the vessel 11. the flow of cooling medium in the jacket 13 may be discontinued.

Furthermore, the dyestulis and chemicals added during d the dyeing procedure in the auxiliary vessel ll have sul'licient period in the vessel 11 to assure thorough mixing and dissolution as a result of circulation by the pump 9 through the conduit 14.

The safety valve 19 at the outlet to the conduit l7 and at the upper part of the vessel 1 will be adjusted to a slightly higher opening pressure than the overflow valve 15. For example, whereas the valve 19 will be set at four to live atmospheres, the valve 15 will be set at four atmospheres.

The opening pressure of the valve 15, however, will be the decisive pressure to determine the pressure maintained in the circuit of the conduits 4 and 5.

In operation, the closed treating vessel 1 is filled with material 6 to be dyed and then is filled with the dye liquor by the auxiliary pump 9.

During this filling operation which may either be from the vessel 11 or from a separate dyeing liquor supply, the main vent valve 2% in the lid of the container 1 is open.

When the filling has been completed, the vent valve 2% will be closed.

The auxiliary pump 9 is then regulated to feed the conduit 14 instead of the conduit 8 by turning the valve 13.

At this time the heater 21 in the base of the container 1 is turned on and the circulating pump 3 is started.

Any volume increase caused by heating of the bath will cause a tlow from container 1 through conduit 17 past the valve 15 and into the expansion vessel 11.

The liquor being discharged will be cooled by the cooling jacket 18 to a temperature low enough so that the temperature will remain below the boiling temperature in the vessel 11.

As soon as the maximum temperature for the treating bath has been reached in the container 1, there will be no further overflow through the conduit 17 into the vessel 11.

The cooling medium for the flow into the jacket 18 may then be turned off. The elevated pressure on the treating bath in the vessel 1 which prevents boiling and evaporation is applied by the auxiliary pump 9.

The pressure of this pump is determined by the opening pressure of the overflow valve 15 which acts both upon the conduit 14 as well as the conduit 17.

During the circulation of the treated liquor in the container 1 by the circulating pump 3, it is possible to introduce into the auxiliary vessel 11 any necessary dyestufis and treating chemicals which will be well dissolved and mixed by reason of the circulation by the pump 9 and the conduit 14.

If additional dye liquor is to be introduced into the circuit of the conduits 4 and 5, and the discharge through the conduit 37 is not suificient, such excess may be discharged through the discharge outlet 22.

The essential feature of the present invention resides in the fact that the auxiliary pump 9 may be switched from feeding liquor into the tank 1 or in circulating liquor into the tank 11.

This arrangement is greatly superior to a system in which the pump 9 feeds cold liquor into the circuit of the lines 4 and 5 to maintain the pressure in the vessel 1.

The present arrangement avoids continuous feed of cold liquor into the pressure vessel and hot liquor is only discharged from the vessel 1 when additional dye liquor must be added.

This will greatly economize on heat consumption in the vessel 1 and only relatively small amounts of heated liquor will be discharged into the vessel 11.

As many changes could be made in the above wet treatment of textiles, and many widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

Having now particularly described and ascertained the nature of the invention, and in what manner the same is to be performed, what is claimed is:

l. A system for the high temperature circulating dyeing of yarns on spools of the type in which the hot dye liquor is discharged from the circulating dye bath only when additional cold fresh dye liquor is being added to the circulating liquor with the removal of a corresponding amount of dye liquor from the circulating liquor and in which the hot dye liquor is circulated without withdrawal of the hot liquor and without feed of additional cold fresh dye liquor into the circulating dye both during the circulating dyeing operation, said system comprising a main dyeing vessel having a transverse liquor header and a plurality of perforated tubular supports extending vertically upwardly from and in communication with said header, yarn spools on said perforated supports, parallel conduits extending into said vessel at the bottom thereof, one into the bottom of the vessel directly and the other into the header, a junction conduit between the parallel conduits, a reversible pump in said junction conduit to circulate the dye liquor through the parallel and junction conduits and into the main dyeing vessel, an auxiliary vessel, a circulating system to circulate fresh dye liquor from the bottom into the top of said auxiliary vessel, a pressure pump in said system either to discharge fresh dye liquor into said junction conduit from said auxiliary vessel or to discharge the fresh dye liquor in back to the auxiliary vessel through said circulating system and means to change the discharge of the pressure pump between the junction conduit and the circulating system.

2. A closed apparatus for wet treatment of textile material with hot treating liquor at above 100 C., including a closed vessel containing the textile material, inlet and outlet conduit connections within said vessel to pass hot liquor through the material when fed into the inlet connection and out through the outlet connection, inlet and outlet conduits feeding hot liquor respectively to said inlet and outlet connections, a reversible circulating pump to circulate liquor through said conduits, a junction con duit connecting the outside inlet and outlet conduits at their ends away from the treating vessel, said circulating pump being located in said junction conduit, a supplemental pressure pump, an auxiliary fresh-treating-liquorcontaining vessel, a suction conduit leading from the bottom of the auxiliary vessel to the presure pump to feed fresh liquor thereto and a first pressure conduit leading from the pressure pump, a check valve to prevent reverse flow in said first pressure conduit, a three-way valve on said pressure conduit beyond said check valve, a second pressure conduit leading from said three-way valve to said junction conduit, a third pressure conduit to short circuit treating liquor from said pressure pump back to the auxiliary vessel, said three-way valve being adjustable to connect the first and second pressure conduits in one position and to connect the first and third pressure conduits in an alternative position, a pressure overflow valve on the third conduit at the end of the third conduit to connect the third conduit to the auxiliary vessel when the pressure in the closed vessel is achieved in said third conduit, a connecting conduit connecting the closed vessel to the third conduit before the pressure overflow valve serving as discharge conduit for treating liquor from said closed vessel to the auxiliary vessel past the pressure overflow valve, said discharge taking place when the first and second pressure conduits are connected by said three-way valve and said short circuit of treating liquor taking place when the first and third pressure conduits are connected by said three-vvay valve.

3. A closed apparatus for wet treatment of textile material with hot treating liquor at about 100 C., including a closed liquor filled vessel under superatmospheric pressure containing textile material, a circulating pump to circulate the liquor in the treating vessel, a first circulating conduit system to connect said circulating pump to said treating vessel, an auxiliary vessel, a pressure pump to circulate fresh make-up liquor through said auxiliary vessel, a second circulating conduit system to connect the pressure pump to circulate fresh liquor through the auxiliary vessel and having a return connection to the auxiliary vessel, a valve connection to connect the pressure pump to thefirst circulating system to feed fresh liquor from the auxiliary vessel to the first circulating system and cut off circultaion in the second circulating system, and a discharge conduit from the treating vessel connected to and leading to the second circulating system before the return connection to the auxiliary vessel, a check valve to prevent reverse flow in said second circulating system adjacent the pressure pump and a pressure overflow valve in the second circulating system at the return connection of the second circulating system to the auxiliary vessel to open at the pressure of the closed vessel.

4. A closed apparatus for Wet treatment of textile material with hot treating liquor at about C., including a completely filled closed vessel containing the textile material to be treated with the hot treating liquor under pressure, internal conduits extending through said textile material to carry liquor passing through said textile material, a reversible circulating pump to circulate liquor through the closed vessel, external conduits respectively connecting said pump to said vessel and to said internal conduits to feed liquor from said pump through said internal conduits and through said vessel between the inlet and outlet of said pump, a supplemental pressure pump, an auxiliary fresh treating liquor containing vessel, said pressure pump serving to feed fresh liquor to the closed vessel and alternatively to short circuit treating liquor from said pressure pump back to the auxiliary vessel, additional external conduits connected to and leading from said pressure pump to receive liquor from the bottom of the auxiliary vessel and feed it to said pressure pump and from the pressure pump to the first mentioned external conduits and return conduit leading back to the upper part of the auxiliary vessel and valve means on said additional conduits to connect said pressure pump alternately to said additional external conduits and to said return conduits to said auxiliary vessel, a connecting conduit connecting the closed vessel to discharge treating liquor from said closed vessel to the auxiliary vessel, said discharge taking place when said pressure pump is feeding fresh liquor to the closed vessel and a pressure relief valve on said connecting conduit to relieve liquor from the first vessel to the auxiliary vessel through said connecting conduit.

5. A closed apparatus for wet treatment of textile material with hot treating liquor at above 100 C., including a closed liquor filled vessel under superatmospheric pressure containing textile material to be treated with hot treating liquor, a circulating pump to circulate the liquor in the treating vessel with the hot treating liquor, a first circulating conduit system to connect said circulating pump to said treating vessel, an auxiliary vessel, a pressure pump to circulate fresh make-up liquor through said auxiliary vessel, a second circulating conduit system to connect the pressure pump to circulate fresh liquor through the auxiliary vessel and having a return to the auxiliary Vessel, means including a valve to connect the pressure pump to the first circulating system to feed fresh liquor from the auxiliary vessel to the first circulating system and cut off circulation in the second circulating system, a discharge conduit from the treating vessel leading to the second circulating system before the return to the auxiliary vessel, a cooling jacket on said discharge conduit, a check valve to prevent reverse flow in said second circulating system adjacent the pressure pump and a pressure overflow valve in the scond system at the return of the second circulating system to the auxiliary vessel to open at the pressure of the closed vessel.

6. A closed apparatus for wet treatment of textile material with hot treating liquor at above 100 C., including a closed liquor filled vessel under superatmospheric pressure containing textile material to be treated with hot treating liquor, a circulating pump, a first circulating sys tern including first and second inlet and outlet conduits connecting the circulat'mg pump to said treating vessel, an auxiliary vessel, a pressure pump to circulate fresh make-up liquor through said auxiliary vessel, a second circulating conduit system to connect the pressure pump to circulate fresh liquor through the auxiliary vessel and having a return to the auxiliary vessel, means including a valve to connect the pressure pump to the first circulating system to feed fresh liquor from the auxiliary vessel to the first circulating system and cut off circulation in the second circulating system, said second circulating system including a third conduit from the auxiliary vessel to the pressure pump to supply fresh liquor to the pressure pump, a fourth conduit from the pressure pump to the valve, a fifth conduit from the valve to the first circulating system and a sixth return flow conduit from the valve to the auxiliary vessel, said valve alternately connecting said fourth conduit to said fifth conduit to supply fresh liquor to the first system and said fourth conduit to said fifth conduit to return fresh liquor to the auxiliary vessel and a discharge conduit from the treating vessel and a pressure overflow valve in the discharge conduit to open at the pressure of the closed vessel when fed by the pressure pump, said discharge conduit leading to said auxiliary vessel and said overflow valve being opened when said first valve permits flow from the fourth conduit to the fifth conduit.

7. A closed apparatus for wet treatment of textile material with treating liquor at a temperature exceeding 100 C. of the type having a closed liquor filled treating vessel containing textile material to be treated with circulating hot treating liquor and an auxiliary vessel containing a supply of fresh treating liquor, comprising a circulating pump to circulate the treating liquor through the textile material in the closed vessel, and a second pump for generating a superatmospheric pressure avoiding evaporation of the above 100 C. heated treating liquor in the closed vessel and for supplying additional quantities of treating liquor to the circulating treating liquor, a connecting conduit system having first inlet and second outlet connections between the circulating pump and the treating vessel, and a third connection from the auxiliary vessel to the second pump and fourth and fifth connections from the second pump respectively to the treating vessel and to the auxiliary vessel and valve means alternatively to connect said second pump to said fourth and fifth connections, a discharge connection from the trea ing vessel leading to the fifth connection, and a pressure control valve to maintain pressure in said fifth and dis- O Q charge connections to prevent discharge into said auxiliary except at pressure in the treating vessel.

8. A closed apparatus for wet treatment, particularly dyeing of textile material with treating liquor at a tem perature exceeding 0., comprising a circulating pump to circulate the treating liquor through the textile material in the closed apparatus, said closed apparatus including a closed tank, an auxiliary open vessel containing fresh liquor, and a second pump for generating a superatmospheric pressure avoiding an evaporation of the above 100 C. heated treating liquor in the closed apparatus and for supplying if needed additional quantities of dyestufi in the circulating treating liquor, a first outlet conduit of the second pump being connectable alternately either to a third conduit to feed fresh liquor to the circulated treating liquor, and to a second conduit leading back to the auxiliary vessel, valve means connected to said first, second and third conduits to provide for said alternate connection from the first conduit to the second and third conduits, an auxiliary relief fourth conduit from the closed tank to the auxiliary vessel, a pressure relief means on the auixilary conduit to feed liquor from the closed tank to the auxiliary conduit when the second pump is connected to the third conduit including an overflow valve to be opened at superatmospheric pressure avoiding the evaporation of the treating liquor, and a conduit system including said first, second, third and fourth conduits and also having inlet and outlet connection conduits to the closed apparatus, said connection conduits forming a circulating system including the closed tank and the circulating pump.

9. Apparatus as claimed in claim 8, wherein the auxiliary conduit simultaneously serves as return conduit for a volume of treating liquor pressed out from the closed apparatus into the auxiliary vessel by the corresponding volume of the added dyestuff introduced by the second pump into the circulating treating liquor.

10. Apparatus as claimed in claim 8, wherein the auxiliary conduit is provided with a cooling jacket.

References Cited in the file of this patent UNITED STATES PATENTS 1,327,662 Dudley Jan. 13, 1920 2,577,727 Abbott Dec. 11, 1951 FOREIGN PATENTS 335,306 Italy Feb. 4, 1936 514,045 Italy Feb. 8, 1955 527,097 Belgium Mar. 31, 1954 666,743 France May 28, 1929 OTHER REFERENCES German application, M 18,442, printed Jan. 19, 1956.

Claims

4. A CLOSED APPARATUS FOR WET TREATMENT OF TEXTILE MATERIAL WITH HOT TREATING LIQUOR AT ABOUT 100* C., INCLUDING A COMPLETELY FILLED CLOSED VESSEL CONTAINING THE TEXTILE MATERIAL TO BE TREATED WITH THE HOT TREATING LIQUOR UNDER PRESSURE, INTERNAL CONDUITS EXTENDING THROUGH SAID TEXTILE MATERIAL TO CARRY LIQUOR PASSING THROUGH SAID TEXTILE MATERIAL, A REVERSIBLE CIRCULATING PUMP TO CIRCULATE LIQUOR THROUGH THE CLOSED VESSEL, EXTERNAL CONDUITS RESPECTIVELY CONNECTING SAID PUMP TO SAID VESSEL AND TO SAID INTERNAL CONDUITS TO FEED LIQUOR FROM SAID PUMP THROUGH SAID INTERNAL CONDUITS AND THROUGH SAID VESSEL BETWEEN THE INLET AND OUTLET OF SAID PUMP, A SUPPLEMENTAL PRESSURE PUMP, AN AUXILIARY FRESH TREATING LIQUOR CONTAINING VESSEL, SAID PRESSURE PUMP SERVING TO FEED FRESH LIQUOR TO THE CLOSED VESSEL AND ALTERNATIVELY TO SHORT CIRCUIT TREATING LIQUOR FROM SAID PRESSURE PUMP BACK TO THE AUXILIARY VESSEL, ADDITIONAL EXTERNAL CONDUITS CONNECTED TO AND LEADING FROM SAID PRESSURE PUMP TO RECEIVE LIQUOR FROM THE BOTTOM OF THE AUXILIARY VESSEL AND FEED IT TO SAID PRESSURE PUMP AND FROM THE PRESSURE PUMP TO THE FIRST MENTIONED EXTERNAL CONDUITS AND RETURN CONDUIT LEADING BACK TO THE UPPER PART OF THE AUXILIARY VESSEL AND VALVE MEANS ON SAID ADDITIONAL CONDUITS TO CONNECT SAID PRESSURE PUMP ALTERNATELY TO SAID ADDITIONAL EXTERNAL CONDUITS AND TO SAID RETURN CONDUITS TO SAID AUXILIARY VESSEL, A CONNECTING CONDUIT CONNECTING THE CLOSED VESSEL TO DISCHARGE TREATING LIQUOR FROM SAID CLOSED VESSEL TO THE AUXILIARY VESSEL, SAID DISCHARGE TAKING PLACE WHEN SAID PRESSURE PUMP IS FEEDING FRESH LIQUOR TO THE CLOSED VESSEL AND A PRESSURE RELIEF VALVE ON SAID CONNECTING CONDUIT TO RELIEVE LIQUOR FROM THE FIRST VESSEL TO THE AUXILIARY VESSEL THROUGH SAID CONNECTING CONDUIT.