GB1588119A

GB1588119A - Vapour condenseres

Info

Publication number: GB1588119A
Application number: GB5224476A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1976-12-15
Filing date: 1976-12-15
Publication date: 1981-04-15

Description

(54) IMPROVEMENTS IN AND RELATING TO VAPOUR CONDENSERS (71) I, PHILIP NEVILLE JUDSON, a British Subject of 27 Fincham's Close, Linton, Cambridge, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following state ment :- Field of the invention This invention concerns condensers of the type used to condense vapours and the like.

Background to the invention Any cooled vessel can be used as a con denser and thus a piece of tube which is cooled by contact between its external surface and the surrounding air and into which hot vapour is passed will under appropriate circumstances act as a condenser. Greater efficiency is achieved by artificially cooling the tube and in the conventional Liebig condenser, the tube is surrounded by a second tube and the space between the two tubes is filled with water which is supplied to the space under pressure so as to be forced to flow therethrough and to constitu e a cooling jacket surrounding the inner tube.

Such condensers have a limited thermal capacity and it is possible for the condensing operation to cease partially or completely if there is a drop in the pressure of the water supplied to the water jacket. Typical con nections to the water jacket are simple push fit connections and a rise in water pressure can lead to a flooded laboratory.

Since such a condenser is usually attached to the cold water supply main, considerable variation in pressure can be expected during a 24-hour period and problems such as those outlined can become of paramount import ance if an experiment has to be carried out under controlled conditions for a long period of time or if the experimental ap paratus has to be left unattended.

Disadvantages of known apparatus Conventional Liebig condensers require a large volume of water since they operate on a continuous flow basis, require to be located near to a tap on the cold water supply main and also require a suitable drain capable of handling the quantity of water which is to be discharged from the apparatus. It is not always convenient to provide such services and in any case the waste of water is undesirable.

Object of the invention With these defects in mind, it is an object of the present invention to provide an alternative form of condenser for condensing hot vapours etc. which does not need to be connected to a water supply nor be located near to a drain and the operation of which does not involve the waste of considerable quantities of water.

The invention According to the present invention apparatus for condensing hot vapours and the like comprises a condensing region which includes at least one surface (the condensing surface) on which hot vapours will condense and through which heat is transferred to a heat transfer fluid such as water or oil, at least one thermally conductive heat sink and a circulatory heat transfer path for the heat transfer fluid wherein said fluid is heated at the condensing surface and is cooled at the heat sink.

As employed herein the term "heat sink" is intended to mean any body which is adapted to receive and readily dissipate heat by radiation and convection.

The heat sink may be joined to and supported by apparatus incorporating the condensing region. Alternatively the apparatus containing the condensing region may be supported by the heat sink.

The heat transfer path preferably includes a first section for transferring heated fluid from the condensing region to a fluid path through the heat sink and a second section for transferring fluid from the opposite end of the fluid path through the heat sink, after it has been cooled by passing therethrough, to return it to the condensing region to pick up heat once again from the said condensing surface. The joints between the apparatus containing the condensing region and the heat sink may comprise, at least in part, members defining said first and second sections of the heat transfer path.

Preferably the heat sink is detachable from the remainder of the apparatus. This will permit an alternative heat sink to be fitted or the existing heat sink to be cleaned or the apparatus containing the condensing region to be repaired or cleaned or replaced.

In one embodiment of the invention the condensing region comprises at least part of the length of an inner cylindrical member and the heat transfer path includes an annular region around the internal cylindrical member which is bounded by an outer cylindrical member bonded at opposite ends to the said internal cylindrical member, pipe connections extending laterally from the outer cylindrical member at opposite ends thereof to communicate with a fluid path through the heat sink.

By forming both the inner and outer cylindrical members in the said one embodi ment. from glass, the interior of the condensing region can be observed.

The area of the condensing surface in the said one embodiment of the invention may be increased as in the so-called double surface Liebig condenser, by providing a tube of small diameter within the interior of the inner cylindrical member which communicate through apertures in the wall of the latter with the body of fluid in the annular region.

The invention will now be described by way of example with reference to the accompanying drawings.

In the drawings Fig. 1 is a side elevation in cross-section of a condenser embodying the invention, Fig. 2 is a perspective view of the unit shown in Fig. 1, and Fig. 3 is a plan view in cross-section on the line A-A of the unit shown in Fig. 1.

Description of embodiment shown in the drawings Figs. 1 to 3 of the drawings refer to an embodiment of the invention comprising a modified Liebig condenser having an inner tube 10, inlet and outlet pipes 12 and 14 which extend both on the same side of the condenser and an outer tube 16 which forms with the inner tube 10, a water jacket.

Gland nuts 18 and 22 and seals 20 and 24 serve to join the inlet and outlet pipes 12 and 14 to connecting tubes 26 and 28 which are threadedly engaged in threaded ports in a central web 30 of a heat sink having cooling vanes 32 which extend from the central web 30 as can best be seen in Fig. 2.

The central web includes a lengthwise drilling 34 which is closed at the lower end by a bung 36 and at its upper end by a filler cap 38 which incorporates a pressure relief safety valve having a spring 40.

When in use the passage 34, connecting tubes 26, 28 and jacket 16 are filled with a liquid such as water or oil. Typically a space is left in the region of the drilling 34 denoted by the reference numeral 42 so as to allow for expansion of the water or oil.

Heat from hot vapours entering the lower end of the tube 10 is transmitted through the walls of the tube to the fluid in the jacket 16 surrounding the central tube. In known manner the heated liquid in the jacket 16 rises and transfers via connecting tubes 12 and 26 to the upper end of the passage 34.

The heat sink is formed from material having a high thermal conductivity such as aluminium or copper or steel including stainless steel and heat from the liquid is immediately transferred to the heat sink which radiates the heat and causes the temperature of the liquid to drop as it is displaced through the passage 34 to return to the condenser j acket via the lower connecting tubes 38 and 14.

Screw-threaded joints between the web 30 of the heat sink and the connecting tubes 26 and 28 are shown in Fig. 1 but alternatively (not shown) the joints may be made by pressing in tubes which are turned to a close fit or by welding or brazing instead of using screw-threaded joints.

Where the length of the condenser is approximately 200 mm it has been found that for the average ambient temperatures, (i.e.

in the range 15 to 20"C) a heat sink having a surface area of 2000 scum2 is required.

The heat sink may be blackened to improve efficiency and further cooling may be achieved by inducing a forced draught as by a fan 44 (see Fig. 2).

A temperature sensor such as a thermocouple 46 as shown in Fig. 2 may be attached to the heat sink and used to determine the operating temperature of the heat sink and as a corollary the operating temperature of the condenser. An electrical signal derived from the temperature sensor may be used after amplification to control the operation of the fan such as 44 and if the temperature is still exceeded to control the shutting down of the plant (not shown) producing the vapour to be condensed.

The joints between the inlet and outlet tubes to the jacket 16 and the connecting tubes (12, 26 and 14, 28) may be conventional ball and socket or conical joints instead of the sealed gland joints as shown in Fig. 1.

Alternatively flexible tubing may be incorporated which is a simple push fit over the two tubes (12 and 26 at the upper end and 14 and 28 at the lower end).

All parts of the apparatus other than the heat sink and gland seals may be made of any suitable material which is not corroded by water and is able to withstand moderate heat and the corrosive atmosphere of a laboratory.

Such materials as polyvinylchloride, nylon, h.d. polyethylene, polypropylene, aluminium, copper, stainless steel, protected steel and glass may be used. In practice the condensing tube 10 and jacket 16 will be made of glass.

The filler cap may be threaded as shown or may be formed as a push fit in the drilling 34, and in that event may not include the pressure relief safety valve, since the bung 36 can be designed to be blown out of the drilling in the event of an excess pressure inside.

Also, the drilling 34 may be in a rod which is essentially of circular cross-section but which includes at least one flat surface against which the heat sink can be held in close contact as by screws, or rivets or by brazing or welding.

Instead of forming the passage 34 by drilling, the heat sink may be formed by an extrusibn process and the passage 34 formed simultaneously as part of the extrusion process, so that no separate drilling is required.

Although not shown the heat transfer path between the condensing surface and the heat sink may include one or more heat transfer pipes of the type described in British Patent Specification No. 1027719.

In order to improve the efficiency of the device shown in Figs. 1 to 3, forced circulation of the heat transfer fluid in the heat transfer path (formed by the jacket 16, passage 34 and connecting tubes 26 and 28) may be employed, by incorporating one or more pumps in the for example one of the connecting tubes 26 and 28.

WHAT I CLAIM IS:- 1. Apparatus for condensing hot vapours comprising a condensing region which includes at least one surface (the condensing surface) on which hot vapours will condense and through which heat is transferred to a heat transfer fluid such as water or oil, at least one thermally conductive heat sink and a circulatory heat transfer path for the heat transfer fluid wherein said fluid is heated at the condensing surface and is cooled at the heat sink.

2. Apparatus as claimed in claim 1 in which the heat sink is joined to and is supported by apparatus incorporating the condensing region.

3. Apparatus as claimed in claim 1 in which that section of the apparatus containing the condensing region is supported by the heat sink.

4. Apparatus as claimed in claim 1 in which the heat transfer path includes a first section for transferring heated fluid from the condensing region to a fluid path through the heat sink and a second section for transferring fluid from the opposite end of the fluid path through the heat sink to return it to the condensing region.

5. Apparatus as claimed in claim 4 in which the joints between the section of the apparatus containing the condensing region and the heat sink comprise at least in part, members defining said first and second sections of the said heat transfer path.

6. Apparatus as claimed in any of the preceding claims in which the heat sink is detachable from the remainder of the apparatus.

7. Apparatus as claimed in claim 1 in which the condensing region comprises at least part of the length of an inner cylindrical member and the heat transfer path includes an annular region around the internal cylindrical member which is bounded by an outer cylindrical member bonded at opposite ends to the said internal cylindrical member, the said annular region being filled with the heat transfer fluid, pipe connections extending laterally from the outer cylindrical member at opposite ends thereof serving to communicate the said annular region with a fluid path through the heat sink.

8. Apparatus as claimed in claim 7 in which the inner and outer cylindrical members are formed from glass so that the interior of the condensing region can be observed.

9. Apparatus as claimed in claim 7 or 8 further comprising a tube of smaller diameter within the interior of the inner cylindrical member which communicates through apertures in the wall of the latter with the body of fluid in the annular region thereby increasing the surface area of the condensing surface within the interior of the inner cylindrical member.

10. Apparatus as claimed in any of the preceding claims further comprising fan means for inducing a draught of air over the heat sink to improve the cooling characteristics thereof.

11. Apparatus as claimed in any of the preceding claims further comprising temperature sensing means for producing an electrical signal which is proportional to the temperature of the heat sink.

12. Apparatus as claimed in claim 11 wherein the electrical signal is employed to control the operation of the fan to cause the latter to operate and induce a cooling draught in the -event that the temperature of the heat sink exceeds a predetermined value.

13. Apparatus as claimed in any of the preceding claims wherein the heat sink is formed from aluminium or an aluminium alloy.

14. Apparatus as claimed in any one of claims 1 to 13 wherein pump means is provided to circulate the heat transfer fluid from the jacket to the heat sink and vice versa.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. h.d. polyethylene, polypropylene, aluminium, copper, stainless steel, protected steel and glass may be used. In practice the condensing tube 10 and jacket 16 will be made of glass. The filler cap may be threaded as shown or may be formed as a push fit in the drilling 34, and in that event may not include the pressure relief safety valve, since the bung 36 can be designed to be blown out of the drilling in the event of an excess pressure inside. Also, the drilling 34 may be in a rod which is essentially of circular cross-section but which includes at least one flat surface against which the heat sink can be held in close contact as by screws, or rivets or by brazing or welding. Instead of forming the passage 34 by drilling, the heat sink may be formed by an extrusibn process and the passage 34 formed simultaneously as part of the extrusion process, so that no separate drilling is required. Although not shown the heat transfer path between the condensing surface and the heat sink may include one or more heat transfer pipes of the type described in British Patent Specification No. 1027719. In order to improve the efficiency of the device shown in Figs. 1 to 3, forced circulation of the heat transfer fluid in the heat transfer path (formed by the jacket 16, passage 34 and connecting tubes 26 and 28) may be employed, by incorporating one or more pumps in the for example one of the connecting tubes 26 and 28. WHAT I CLAIM IS:-

1. Apparatus for condensing hot vapours comprising a condensing region which includes at least one surface (the condensing surface) on which hot vapours will condense and through which heat is transferred to a heat transfer fluid such as water or oil, at least one thermally conductive heat sink and a circulatory heat transfer path for the heat transfer fluid wherein said fluid is heated at the condensing surface and is cooled at the heat sink.

15. Apparatus for condensing hot vapours

constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in Figs. 1 to 3 of the accompanying drawings.