GB2165932A

GB2165932A - Recuperative waste water trap

Info

Publication number: GB2165932A
Application number: GB08426591A
Authority: GB
Inventors: Robert Alan Chard
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-10-19
Filing date: 1984-10-19
Publication date: 1986-04-23
Also published as: GB2165932B; GB8426591D0

Abstract

A waste water trap or chamber 1 capable of holding waste water is provided with a means of transferring heat from the waste water to cooler water (although other cooler fluids may be used) through a thermal conducting material 4 which separates the two fluids. <IMAGE>

Description

SPECIFICATION Recuperative waste water trap This invention relates to waste water traps or chambers capable of holding waste water.

Waste water usually passes through a trap before discharge to drains. In most cases the waste water is at a higher temperature than the available water supply, having been heated for washing or some other purpose. The recovery of some of the heat which is normally lost in the waste water has two benefits, firstly there is a saving of energy and secondly the temperature of the waste water is reduced. This invention can be used to reduce the cost of water heating by causing fresh water to be warmed, thereby reducing the amount of fuel which is required to heat the water. This invention can be used in conjunction with showers or similar apparatus where there is a continuous flow of waste water whilst the apparatus is in use although it will be noted that some forms of construction of the invention are suitable for use with intermittent flows of waste water.

An object of the present invention is to recover heat from waste water. Another object is to reduce the temperature of waste water.

According to the present invention a waste water trap of chamber capable of holding waste water is provided with a means of transferring heat to cooler water (although other fluids may be used) through a thermal conducting material which separates the two fluids. By way of example different forms of the invention are schematically illustrated in the accompanying drawings.

Fig. 1 shows a trap or chamber in which waste water enters the body 1 through an inlet 2, and leaves through an exit 3. In this example the thermal conducting material 4 which separates the two fluids is a thermal conducting tube. Cooler fluid enters the heat exchange maens through an inlet 5 and leaves after being heated through an exit 6. In this example the flow of cooler fluid is counter to the flow of waste water, this need not be so, but has the advantage that there is a greater temperature difference between the two fluids, thereby promoting good heat transfer. In this example only a single tube has been shown to illustrate the heat exchange means. A more elaborate heat exchange surface can be provided to increase- the heat recovery by providing a greater surface area through which the heat may pass.The shape of the heat transfer surface may be arranged to reduce the flow obstruction within the trap or chamber. The shape of the heat exchange surface may be arranged to prevent or reduce the risk of suspended matter (eg hair) being trapped.

Fig. 2 shows a trap or chamber in which the heat transfer means is a jacket 7 which embraces the trap or chamber externally. In this example the thermal conducting material 4 is the wall of the trap or chamber. This method of construction has the advantage that only the wall of the trap or chamber need be made from the thermal conducting material although the whole trap or chamber could be made from this material. The external jacket is shown extending up to the level of the waste water within the trap or chamber although it could embrace the whole of the trap or chamber or be formed in two or more sections which embrace differenct parts of the trap or chamber. One example of such an arrangement is shown in Fig. 3 where two external jackets are shown. When the heat transfer means comprises two or more separate parts the flow of cooler fluid can be through them in series or parallel.In the example in Fig. 3 the cooler fluid can be routed through the external jackets serially by connecting the exit of the first jacket 6 to the inlet of the second jacket 5A. If parallel flow is used then a flow restriction can be provided at the entry of any or all of the separate heat transfer means to distribute the flow of cooler fluid more evenly between the external them.

Fig. 4 shows an example in which the heat transfer means projects upwards within the trap or chamber. This example shows the cooler fluid inlet 5 extended so as to improve the heat transfer by projecting the cooler fluid directly onto the heat transfer surface. Projecting the heat transfer means upwards has the advantage that it can be made readily removable. It may be made to replace the lower plug or access means which is normally provided to facilitate the removal of foreign matter. Fig.

5 shows an example in which the heat transfer means takes the form of a jacket within the trap or chamber. In this example the upper edge of the heat transfer surface 8 has been shown shaped in a way designed to reduce the possibility of foreign matter being trapped and to reduce the flow obstruction. In this example the cooler fluid inlet 5 is shown low in the body of the heat exchange means whilst the outlet is shown high. The inlet can be diametrically opposite the outlet as shown in this example. This arrangement serves a dual purpose. Firstly the cooler fluid is made to pass more evenly around the body of the trap or chamber, secondly any air or other gas which might otherwise collect within the heat exchange means and so prevent cooler fluid coming into contact with part of the heat exchange surface is permitted an easy escape.

Fig. 6 shows an example in which the heat transfer means is in the form of a spirally coiled tube, although the tube can be bent into other shapes. Any external shape of tube could be used.

Fig. 7 shows how the wall of the trap or chamber itself can be made from a spiral of thermal conducting tube which is appropriately sealed 9 between the outer walls of the tube to form a containing wall. The seal between the tubes can be formed within the trap or chamber 10 or external to the trap or chamber 11. In this example round tube has been shown although tube of other shapes can be used.

Fig. 8 shows how different parts of the trap or chamber can be incorporated within the heat transfer means to increase the surface area available for heat exchange.

Fig. 9 shows an example in which the volume of waste water has been increased by making the trap or chamber physically large.

This arrangement retains waste water in the body of the invention for a longer period of time thereby allowing more heat to be recovered. The heat transfer means used can be any one or combination of those already described.

One or more vertical baffles can be provided within the body of the trap or chamber extending upwards from the floor of the trap or chamber or downwards from the roof. Fig. 10 shows an example in which a series of vertical baffltes extending upwards from the base of the trap or chamber are provided. These baffles may have decreasing vertical height when considered in the order that they will be encountered by waste water flowing through the trap or chamber, thus it will be noted that the vertical height of baffle 12 is greater than the vertical height baffle 13. These baffles serve to separate the waste water into compartments. The advantage of this arrangement is that the whole of the waste water is prevented from mixing and so resides in a series of compartments of decreasing temperatures.

The heat transfer means used can be any one or combination of those already described.

Fig. 11 is a horizontal section of the apparatus shown in Fig. 10 between the points A-A. This shows the waste water flowing mainly in a straight path as indicated by the arrows. Fig. 12 shows a horizontal section through a trap or chamber with a different arrangement of baffles 17, 18, 19, 20 extending upwards from the floor of the trap or chamber. For clarity the heat transfer means has not been shown in Fig. 12 but any one or combination of those already described can be used. Baffle 17 is the highest, baffle 18 is the next highest, baffle 19 is smaller than baffle 18 but higher than baffle 20, baffle 20 is the lowset. In this arrangement the waste water is made to flow in different directions as it passes from one compartment to the next.

Fig. 13 shows a different arrangement of baffles where one, 15, extends downwards from the roof of the trap or chamber whilst two, 14 and 16, extend upwards. The purpose of the baffles extending upwards from the floor of the trap or chamber above the surface of the waste water is to divide the waste water into a series of compartments thereby peventing the whole mass of trapped waste water from mixing and attaining a uniform temperature. The purpose of the baffles which extend downwards from the roof of the trap or chamber combined with the baffles extending upwards from the floor of the trap or chamberis to make the waste water describe a ''U'' shape thereby bringing it into better contact with the heat transfer means.It should be noted that in this example one of the baffles extending upwards 14 does not teach the surface of the waste water this illustrates how the whole of the heat transfer means can be kept in contact with the waste water. The construction of the trap or chamber can be modified so that the heat transfer means passes through the baffles below the surface of the trapped waste water. There can be any number of baffles, the limiting factor on both the number and height of the baffles is the obstruction to flow which is caused.

Fig. 14 shows a horizontal section through a trap or chamber as described by Fig. 2. Fig.

14 shows the cooler fluid inlet 5 and outlet 6 diametrically opposite each other. In some applications it is convenient to have these pipe connections closer together as shown in Fig.

15. This is acomplished by fitting a single vertical baffle 21 or series of vertical baffles 21, 22, 23, 24 within the space occupied by the cooler fluid. In this example four baffles have been shown for illustration, more or less baffles can be used.

Fig. 16 is a vertical section through such a trap or chamber and shows the baffles 22, 23, 24 and the appropriate sections which are cut out to enable the cooler fluid to flow through. Baffle 22 is complete and has no cutout. Baffles 21 and 24 have cutouts at their upper end whilst baffle 23 has a cutout 25 at its base. The overall effect of these baffles is to cause the cooler fluid to rise and fall as it passes around the body of the trap or chamber. In this example four baffles have been illustrated other numbers can be used. In the examples of the invention which have a jacket type of construction the cooler fluid has entered through a tube at right angles to the main body of the trap or chamber. If the cooler fluid inlet 5 is set at an angle as shown in Fig. 17 when the cooler fluid is forced to swirl around the space between the inner and outer walls 27 and 26 respectively. An alternative arrangement is shown in Fig. 18 where a deflector 28 is provided to cause the cooler fluid to swirl around the jacket.

To promote better heat transfer it is desirable to cause the waste water within the trap or chamber to swirl, whether or not this is appropriate depends on the particular construction adopted. Fig. 19 shows one way in which turbulence may be promoted by fitting one or more baffles 29 within the entry 30 to the trap or chamber. The heat transfer means has been omitted from Fig. 19 for clarity but can be any one or combination of those previ ously described. These baffles must not be so large that excessive obstruction to flow is caused or suspended matter is trapped. A helical projection 31 can be provided for this purpose within the body of the trap or chamber itself, a small section being shown in Fig.

19. Swirling within the body of the trap of chamber can be promoted by a variety on means. Fig. 20 shows an example where the heat transfer means is a spiral of tube which has an extension or extensions 32 which are inclined relative to vertical so that waste water flowing through the trap or chamber is made to swirl. The construction ot the apparatus itself can be such that the flow of water entering causes the waste water already within the apparatus to swirl. This can be achieved by setting an inlet for waste water away from the centre of the body of the trap or chamber and inclining the entry with respect to vertical. Fig. 21 shows this when viewed from above, Fig. 22 is a vertical section, showing how the lower portion of the entry tube 30 has been set at an angle with respect to vertical.The whole inlet tube can be made tangential to the body of the trap or chamber as shown in Fig. 23. It should also be noted that the waste water outlet has been shown in Fig. 23 as a tube projecting upwards from the base of the trap or chamber.

Whatever form of heat transfer means is used it may be desirable to use some form of external thermal insulation. The heat transfer means and any insulation should be removable as far as is appropriate to facilitate or allow maintenance or cleaning. It is desirable that any part of the heat transfer means which is located within the trap or chamber should not present any significant obstruction to the flow of waste water.

The examples in the drawings have mainly shown a bottle trap, this is not essential since any configuration which serves to trap or hold some waste water can be used for the purposes of the present invention.

This invention can be incorporated within the body of some types of sanitary appliances for example shower trays.

This invention can be incorporated within apparatus which uses heated water for example dishwashers washing machines and the like. Where more than one charge of heated water is used in the operating cycle of the apparatus into which this invention is incorporated appropriate modifications can be made to the control mechanism to permit heated waste water to be stored. The control mechanism can then direct the fresh cold fluid through the invention to recover heat.

Still larger versions of this invention can retain all the heated waste water from a building and together with an appropriate control mechanism enable incoming cold water to be heated.

Claims

1. A waste water trap or chamber capable of holding waste water which is provided with a means of transferring heat from the waste water to a cooler fluid.

2. A waste water trap or chamber capable of holding waste water in which any part or parts which are wetted by the waste water form a part of the heat transfer means.

3. A waste water trap or chamber capable of holding waste water according to claim 1 or claim 2 wherein said heat transfer means is within said trap or chamber.

4. A waste water trap or chamber capable of holding waste water according to claim 1 or claim 2 wherein said heat transfer means embraces said trap or chamber externally.

5. A waste water trap or chamber capable of holding waste water according to claim 1 or claim 2 wherein said heat transfer means projects upwards within said trap or chamber.

6. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein said heat transfer means consists of more than one surface through which heat transfer can take place.

7. A waste water trap or chamber capable of holding waste water according to any preceding claim which is fitted with one or more vertical baffles which extend upwards from the base of said trap or chamber so that the cross sectional area remaining for flow above any baffle is not smaller than the cross sectional area of the waste water outlet from said trap or chamber.

8. A waster water trap or chamber capable of holding waste water according to claim 7 wherein any said baffle or baffles extend above the surface of the waste water within said trap or chamber thereby causing the waste water to be held in a series of traps or chambers through which said waste water flows.

9. A waste water trap or chamber capable of holding waste water according to claim 8 containing more than one baffle wherein the height of said baffles decreases when said baffles are considered in the order in which they are encountered by the waste water flow.

10. A waste water trap or chamber capable of holding waste water according to any of claims 1 to 6 which is fitted with one or more vertical baffles extending downwards from the roof of said trap or chamber so that the cross sectional area remaining for flow beneath any baffle is not smaller than the cross sectional area of the waste water outlet from said trap or chamber.

11. A waste water trap or chamber capable of holding waste water according to claims 7 to 10 containing one or more vertical baffles which extend upwards from the base of said trap or chamber and one or more vertical baffles which extend downwards from the roof of said trap or chamber.

12. A waste water trap or chamber capable of holding waste water according to claim 11 wherein said baffles extending upwards and downwards alternate when considered in the order in which they are encountered by the waste water flow.

13. A waste water trap or chamber capable of holding waste water according to claim 1 or 2 or 4 or 5 or any claim dependant thereon which incorporates within the space occupied by the cooler fluid any baffle or baffles or the like which distribute the cooler fluid more evenly over the heat transfer surface or surfaces.

14. A waste water trap or chamber capable of holding waste water according to claim 4 or 5 or any claim dependant thereon wherein the cooler fluid enters tangentially.

15. A waste water trap or chamber capable of holding waste water according to claim 4 wherein a baffle or baffles are provided within the space occupied by the cooler fluid causing the cooler fluid to be deflected thereby causing said cooler fluid to describe a circular motion.

16. A waste water trap or chamber capable of holding waste water according to claim 4 which incorporates one or more vertical baffles within the space occupied by the cooler fluid said baffle or baffles causing the cooler fluid to rise and fall.

17. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein one or more baffles are provided within the space occupied by the waste water which cause said waste water to describe a circular motion within the body of said trap or chamber.

18. A waste water trap or chamber capable of holding waste water according to claim 17 wherein said baffle or baffles are attached to or form an integral part of the heat transfer means.

19. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein the waste water enters the body of said trap or chamber tangentially.

20. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein the kinetic energy of the waste water is used to cause the waste water within said trap or chamber to be agitated and or describe a circular motion within the body of said trap or chamber.

21. A waste water trap or chamber capable of holding waste water according to any preceding claim which includes a means of thermally insulating said trap or chamber or heat transfer means.

22. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein any part or parts are removable as appropriate to facilitate or allow maintenance or cleaning.

23. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein said heat transfer means is configured to reduce the obstruction to flow which might otherwise occur.

24. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein said heat transfer means is configured to reduce the likelyhood of suspended matter in the waster water being trapped within said trap or chamber.

25. A waste water trap or chamber capable of holding waste water according to any preceding claim wherein said heat transfer means is configured to prevent gases (normally air) being trapped within the space occupied by the cooler fluid.

26. A waste water trap or chamber capable of holding waste water substantially as described herein with reference to Figs. 1 to 18 of the accompanying drawings.

27. A heat transfer means according to any relevant preceding claim which can be retro-fitted to an existing waste water trap or chamber capable of holding waste water and thereby converting said trap or chamber into a form as herein described with reference to Figs. 1 to 18 of the accompanying drawings.