GB2051596A - Gas-to-liquid condenser - Google Patents

Abstract

A condenser for conversion of gas into liquid in a chemical cleaning machine is disclosed, the condenser comprising a closed vessel (1) for flow therethrough of a liquid coolant (7). Arranged in the vessel (1) is a heat exchanger which is connected in a liquid- and gas-tight manner with the vessel (1). A divided entry chamber member (10) is mounted at the one end of the vessel (1) and a divided exit chamber member (19) at the other end of the vessel (1), the arrangement being such that the gas can be blown by a blower from the entry chamber member (10) through the heat exchanger and into the exit chamber (19). A condensate outlet duct (29) is provided. <IMAGE>

Description

SPECIFICATION Gas-to-liquid condenser The present invention relates to a gas-to-liquid condenser and has particular reference to apparatus for the conversion of gaseous media into liquid media in a chemical cleaning machine in which the media are contained in a closed circuit system and are not let out into the atmosphere.

Known dry-cleaning machines consist of a closable drum which is accessible from outside and into which textiles to be cleaned are introduced. After closure of the drum, a liquid solvent such as perchloroethylene is withdrawn for a supply container and introduced into the drum. Subsequently, the drum is set into rotation for a predetermined cleaning time and this is followed by a centrifuging process in order to remove as much solvent as possible from the stock being cleaned. However, appreciable quantities of solvent, which must be removed before the drum can be opened for withdrawal of the cleaned stock, are still present in the stock to a greater or less degree depending on the properties of the stock. The atmosphere in the drum consists of a mixture of solvent and air.For removal of this mixture from the drum, the drum is connected, after actuation of changeover flaps, to a ring duct in which a blower, a heater element and a cooling element are disposed. The blower serves to impel the gaseous mixture of air and solvent. After a certain period of time, a fresh air flap leading to the drum is opened, a deflecting plate in the ring duct is closed and a blow-off flap is opened so that the gaseous medium could escape into the open. A direct discharge into the atmosphere, however, is not possible because the gaseous medium still contains too high a proportion of solvent, which could be detrimental to health.

Two different systems are known for reducing the proportion of solvent in the gaseous medium to a level permitted by the authorities.

One known system utilises a pipe duct which leads from the blow-off flap of the ring duct to a liquid collector. The collector is connected with a blower which guides the gaseous medium into a container filled with active carbon, this container forming a filter.

After the gaseous medium has passed through the filter, the percentage of the solvent is reduced to the permissible level and the gaseous medium can now be discharged into the open, for example into a chimney. Known active carbon filters have the disadvantage that they are too high in price and require an appreciable amount of energy for their regeneration. Moreover, there are difficulties connected with determining when such a regeneration is required, because the condition of the active carbon, in particular its degree of saturation, cannot be readily checked due to different error possibilities in the machine. Accordingly, a special device is additionally required for determining the degree of saturation.

Furthermore, devices are known in which an active carbon filter is dispensed with. In order to remove the requisite amount of solvent from the gaseous medium and to partially recover the solvent, such devices operate on the basis of a cooling of about - 22" of the gaseous medium. Such devices have the disadvantage that technical complication is involved in their operation, because a cooling machine is needed. A further disadvantage is a high space requirement. It is also disadvantageous that additional energy is consumed.

There is accordingly a need for apparatus which in a simple manner, in particular without mechanical moving parts, with minimum expenditure of energy, and without high maintenance requirements or susceptibility to faults, maintains the degree of concentration of the solvent in the gaseous medium within the legally permitted limits.

According to the present invention there is provided a gas-to-liquid condenser comprising a vessel for liquid coolant, conduit means sealably mounted in the vessel for conducting gas through the vessel for heat exchange with the coolant, and entry and exit chamber means each mounted at a respective one of two opposite ends of the vessel and each defining a partly divided chamber, the condenser being so constructed as to permit the flow from the entry chamber means through the vessel to the exit chamber means of gas impelled by a blower.

The condenser may be so constructed that the interior space of the entry chamber means is subdivided by a sieve-like plate into two compartments, one of which is provided with an inlet port for the gas and the other adjoins a flange which connects the entry chamber means in a gas-tight manner with the vessel.

The conduit means mounted within the vessel preferably comprises two plates, which are connected in a gas-tight manner with the vessel at a spacing from each other and which are provided with apertures, while communicating with the apertures of the plates is a number of tubes which are mounted at a spacing from one another and firmly connected in a gas-tight manner with the plates.

Helical strips of, for example, metal are arranged within the tubes. The vessel is provided with an inlet port and an outlet port, which both communicate with the interior space of the vessel and through which the inflow and outflow of the coolant can take place. In addition, the condenser is constructed so that the interior space of the exit chamber means is partially divided by a baffle plate, which is fastened at its upper end and is generally tongue-shaped, into two compartments, one of which is provided with an outlet port for the gas and the other of which adjoins a flange which connects the exit chamber means in gastight manner with the vessel. An outlet port is provided in the exit chamber means at the lower part of the compartment which is disposed in front of the baffle plate. A pipe, which leads to a container for the condensed solvent, communicates with the outflow port.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawing, which is a schematic sectional view of a gas-to-liquid condenser according to the said embodiment.

Referring now to the drawing, there is shown a condenser comprising a vessel 1, which is of, for example, circular cross-section and is closed at its end by two plates 2 and 2a, which are connected firmly and in a gastight manner with the vessel. The plates 2 and 2a are each provided with a number of apertures into which extend pipes 3, the pipes being connected firmly and in a gas-tight manner with the plates 2 and 2a. The plates 2 and 2a and tubes 3 in their entirety form a heat exchanger, the effectiveness of which is increased by helically twisted metal strips 4, extending within the tubes 3.

Provided on the vessel 1 are an inlet pipe 5 and an outlet pipe 6, which serve for the feed and removal of a liquid coolant 7, in direction of the arrows 8 and 9, respectively. At one end of the vessel 1 there is provided an entry chamber member 10 provided at its end face with an inlet pipe 11, to which the gaseous medium is supplied through a pipe hose duct (not shown) in the direction of the arrow 1 2.

The interior of the member 10 is divided by a sieve-like plate 1 3 into two compartments 14 and 15, with the effect that inflowing gaseous medium is distributed in the compartment 14 in the direction of the arrows 16, flows through the plate 13, and passes into the tubes 3 in the direction of the-arrows 17. The member 10 is provided with a flange 18 by means of which it is pushed onto the vessel 1, the flange 18 being connected to the vessel in a gas-tight manner by any desired means.

At the other end of the vessel I is an exit chamber member 1 9 provided with an outlet pipe 20 through which the gaseous medium can issue in the direction of the arrow 21 and flow into a further pipe or hose duct (not shown). The member 19 is divided into two chambers 23 and 24 by a baffle plate 22 which is generally tongue-shaped in profile.

The baffle plate 22 is connected, at its upper edge only, with the member 1 9 and has a laterally increasing spacing from the side walls of the member 19, while defining a greater passage area at its lower end. The member 1 9 is provided at its end adjacent the vessel 1 with a flange 25, which is pushed onto the vessel and connected in a gas-tight manner therewith. A gaseous medium issuing from the tubes 3 in direction of the arrows 26 after cooling in the heat exchanger impinges in direction of the arrows 26 onto the baffle plate 22 and partially condenses into a liquid, which runs down in drop form from the baffle plate 22 in the direction of the arrow 27.The liquid flows out of the compartments 23 and 24 via an outlet pipe 28, which is connected with a hose duct 29 leading, in the direction of the arrow 30, to a collecting vessel (not shown) for the liquid, i.e. the solvent.

The condenser hereinbefore described may be manufactured as follows: After provision of apertures in the plates 2 and 2a, the ends of the tubes 3 are introduced into these apertures and are connected firmly and in a gas-tight manner with the plates. The resulting unit forms the heat exchanger. Helically twisted metal strips 4 are introduced into the tubes 3 in such a manner that their edges bear firmly against the inside of the tubes. The heat exchanger is pushed into the cylindrical vessel 1, previously provided with the inlet pipe 5 and outlet pipe 6, and the plates 2 and 2a are connection in a gas- and liquid-tight manner with the inside wall of the vessel 1. The entry chamber member 10 is provided with the plate 1 3 and is connected by its flange 1 8 in a gas-tight manner with the vessel 1.It is, however, possible to place the plate 2 not directly against the rim of the vessel 1, but in the interior space of the vessel to a depth corresponding to the desired depth of the compartment 1 5. In this case, the plate 1 3 would close off the rim of the vessel 1 and the member 10 would be shortened so as to consist only of the compartment 14 and flange 1 8. In both embodiments, the flange 18 is connected in a gas-tight manner with the vessel 1. The baffle plate 22 is inserted into the exit chamber member 1 9 and at its upper rim is firmly connected to this member, the member being provided with the outlet pipe 28. Thereafter, the flange 25 of the member 1 9 is connected in a gas-tight manner with the vessel 1. All of the abovementioned parts are made of stainless steel.

After connecting pipes or other duct elements to the five inlet and outlet ports, the condenser is ready for use.

In operation, after completion of the cleaning and centrifuging process in a chemical cleaning machine, the drum of the machine is stopped and valve flaps are switched in such a manner that the interior space of the drum is brought into communication with a ring duct, through which the gaseous medium for the drum is blown by a blower. This gaseous medium consists of air containing a high proportion of the liquid solvent, for example, perchloroethylene. The condenser is incorporated in the ring duct and the gaseous medium flows through this. Before the start of this operation, the coolant 7, which preferably consists of mains water, is fed in direction of the arrow 8 into the vessel 1 and leaves the vessel in the direction of the arrow 9, so as to provide a constant current of coolant to wash around the tubes 3 of the heat exchanger.

The gaseous medium impelled through the ring duct enters in the direction of the arrow 1 2 into the compartment 14 of the entry chamber member 10 and is distributed therein in the direction of the arrows 16, the gaseous medium then passing through the apertures of the plate 1 3 and into the compartment 1 5. From there, the gaseous medium flows in the direction of the arrows 1 7 into the interior of the tubes 3 and is cooled by the coolant 7, this process being enhanced by the strips 4, which exert a braking effect and thus promote heat removal.

After flowing through the tubes 3, the gaseous medium gets into the compartment 23 of the exit chamber member 1 9 and impinges in the direction of the arrows 26 on the baffle plate 22. During this process, a part of the gaseous medium condenses, becomes liquid and flows from the baffle plate 22 in the direction of the arrow 27 into the outlet pipe 28. From there it flows through the hose duct 29 in the direction of the arrow 30 into a collecting container.

The residual gaseous medium now contains a lower proportion of liquid medium, i.e.

solvent, although this proportion is still too high. Therefore, the gaseous medium is conducted around the sides of and underneath the baffle plate so as to pass into the compartment 24 from where it issues through the outlet pipe 20 in the direction of the arrow 21 for return to the ring duct. The gaseous medium is thus recycled in the circuit and reenters the condenser in the direction of the arrow 1 2 for further cooling, further condensation on the baffle plate 22 and further extraction as liquid solvent. The circuit through the condenser is continued until the proportion of solvent in the cleaned stock has attained a percentage which is so low that health risks no longer exist. This operation may typically take a few minutes. Thereafter, the drum of the machine can be opened and the cleaned stock withdrawn.It is self-evident that the feed of the coolant 7 can now be stopped.

The advantages of such a condenser are that it is of relatively simple construction and only mains water is needed as coolant for its operation, whereby consumption of other kinds of energy is obviated. A further advantage is that by contrast with equipment which operates with under-cooling, rotating parts are not needed, which means that the condenser can function substantially without interruption.

The simple mode of construction is advantageous in that it permits manufacture at a favourable price compared with equipment which operates with active carbon filters or with under-cooling. The condenser itself may be relatively small in size and thus requires only a small area for installation compared with the known equipment. It can be arranged above the cleaning machine and thus requires no additional space.

The invention is not restricted to the embodiment hereinbefore described, for example, the profiles of the vessel, plates and tubes can be of any suitable shape, although a round shape is the most advantageous.

Claims (10)

1. A gas-to-liquid condenser comprising a vessel for liquid coolant, conduit means sealably mounted in the vessel for conducting gas through the vessel for heat exchange with the coolant, and entry and exit chamber means each mounted at a respective one of two opposite ends of the vessel and each defining a partly divided chamber, the condenser being so constructed as to permit the flow from the entry chamber means through the vessel to the exit chamber means of gas impelled by a blower.

2. A condenser as claimed in claim 1, wherein the chamber defined by the entry chamber means is divided by a perforated partition element into two compartments, one of the compartments communicating with a gas inlet port and the other compartment adjoining flange means connecting the entry chamber means to the vessel in a gas-tight manner.

3. A condenser as claimed in either claim 1 or claim 2, the conduit means comprising two spaced-apart plates each provided with a plurality of apertures and connected in a gastight manner to the vessel, and a plurality of spaced-apart pipes each connected in a gastight manner to the two plates and each extending within a respective aperture of each plate.

4. A condenser as claimed in claim 3, the conduit means further comprising a respective helical element extending in and along each of the pipes.

5. A condenser as claimed in any one of the preceding claims, wherein the vessel is provided with a coolant inlet port and a coolant outlet port each communicating with the interior space of the vessel.

6. A condenser as claimed in any one of the preceding claims, wherein the chamber defined by the exit chamber means is partially divided into two compartments by a tapered tongue element fastened at its wider end, one of the compartments communicating directly with a gas outlet port and the other compartment adjoining flange means connecting the exit chamber means to the vessel in a gas tight manner.

7. A condenser as claimed in claim 6, wherein said other compartment communicates with a liquid outlet port in the region of the free end of the tongue element.

8. A condenser as claimed in claim 7, wherein the liquid outlet port communicates with a pipe leading to a container for condensate.

9. A gas-to-liquid condenser substantially as hereinbefore described with reference to the accompanying drawing.

10. A cleaning machine for use with a solvent medium carried in a gas current, the machine comprising a condenser as claimed in any one of the preceding claims.