GB2060859A

GB2060859A - Apparatus for collecting the heat discharged through an exhaust pipe of an engine

Info

Publication number: GB2060859A
Application number: GB8029032A
Authority: GB
Original assignee: MERLANG HOLDING SA
Current assignee: MERLANG HOLDING SA
Priority date: 1979-09-19
Filing date: 1980-09-09
Publication date: 1981-05-07
Also published as: FR2465888B1; LU82778A1; NL7906986A; FR2465888A1; JPS56113011A; DE3034122A1; BE885259A

Abstract

The apparatus comprises a reservoir (1) filled with a suitable heat- storage material (12), e.g. sand, a plurality of tubes (10) extending through the reservoir and embedded in the medium, which tubes are or can be connected at one end to the exhaust pipe (23, 2) of the engine and at the opposite end to a conduit (4, 28) for discharge of the engine's exhaust gases transported through the tubes. Means (13, 15-18; 31, 32, 17, 18) are provided for transporting heat from the reservoir to a remote heat exchanger (19) or other consumer, e.g. for central heating. <IMAGE>

Description

SPECIFICATION Apparatus for collecting the heat discharged through an exhaust pipe of an engine This invention relates to an apparatus for collecting the heat discharged through an exhaust pipe of an engine, in particular a ship's engine.

In engines, heat is generated during operation. Commonly a large part of this heat is discharged through the exhaust fumes without its being utilized. It is an object of the present invention to provide an apparatus which collects at least a portion of the heat which otherwise is discharged without utilization.

According to the invention, for this purpose there is provided an apparatus characterized by a reservoir filled with sand or like heatstorage material, a plurality of tubes extending through the reservoir and embedded in the sand, which tubes are at one end in connection with, or adapted to be connected to, the exhaust pipe of the engine, in a suitable manner, and at the opposite end are in connection with or arranged to be connected to, a conduit for discharge of the engine's exhaust gases transported through the tubes, and means for transporting heat from the reservoir to a remote heat exchanger or other consumer.

In the apparatus according to the invention, a major part of the heat which otherwise is discharged through the exhaust gases and is lost in the outer air, is transferred through the tubes to the surrounding sand or other suitable heat-storage medium. During normal operation of an engine, for example, a ship's engine, the sand can thus reach a high temperature of as high as approximately 500"C.

The heat stored in the sand can be withdrawn from it in various ways.

In one embodiment of the apparatus according to the invention, in which the tubes extend between two tube plates, with headers being provided between the wall of the reservoir and the respective tube plates, through which headers the exhaust gases of the engine are supplied and discharged, respectively, the means for transporting heat from the reservoir to a heat exchanger or other consumer consist of conduits between each of the headers and the heat exchanger or other consumer, thereby forming a circuit comprising, respectively, the header for supplied exhaust gases, a first conduit, the heat exchanger or other consumer, a second conduit, the header for exhaust gases to be discharged, and the tubes between the headers, there being provided a blower in one of the conduits for passing gases through the circuit.

In another embodiment of the apparatus according to the invention, the means for transporting heat from the reservoir to a heat exchanger or other consumer consist of one or more other tubes embedded in the sand or other heat-storage material, which other tubes are connected on opposite sides respectively to a first and a second conduit connecting the tubes to the heat exchanger or other consumer, in such a manner that the tubes, the first conduit, the heat exchanger and the second conduit form a closed circuit, and a blower being provided in said closed circuit for circulating through the circuit a heat transporting medium which is maintained in said circuit.

In the heat exchanger or other consumer forming part of, or coupled to, the apparatus according to the invention, the heat supplied is given up, for example, to water of a heating system or a hot-water providing system.

If applied on board ships, the apparatus according to the invention renders a conventional central heating installation superfluous and thus provides a substantial saving in energy. As sand has a high heat capacity, even if the engine is stopped and heat is no longer supplied, it will last a relatively long time before all the heat stored in the apparatus according to the invention has been discharged. On board a ship, therefore, it will be possible to continue operating the central heating system for a considerable time after the engine has been stopped. This is of particular importance in the case of ships for transporting inflammable liquids, such as petrol and the like.In order to prevent explosions, when such ships are loaded or unloaded no "open fire" may be present, which means that beside the engine, a central heating installation operating for example with an oil burner must also be switched off. This means in many cases inconvenience to crew, in particular if loading or unloading takes a considerable time. When the apparatus according to the present invention is used in a central heating installation, this disadvantage does not present itself.

The tubes in the apparatus according to the invention may suitably consist of steel, that is to say, of the same material as the exhaust pipe of the engine itself.

In one suitable embodiment of the apparatus according to the invention, the apparatus is provided with a bypass conduit and with means for causing the exhaust gases from the engine to pass, in full or in part, outside the reservoir through said bypass conduit. Such means may comprise means for measuring the temperature of the exhaust gases supplied and means for diverting the gases from the reservoir to the bypass conduit upon the measurement of a temperature below a selected value.It is also possible for the means to comprise a valve mounted in the conduit to the reservoir downstream of the branch-off point of the bypass conduit, which valve is tiltable so as to shut off the entire conduit, the valve being equipped with a weight arranged relatively to its tilting axis in such a manner that when a small quantity of gas is supplied the weight keeps the valve in its closed position and when larger amounts of gas are supplied such amounts force open the valve against the weight.

At times when the engine is running slowly relatively little heat is created and the exhaust gases will have a relatively low temperature. If such low-temperature exhaust gases are passed through the apparatus in which sand with a relatively higher temperature is present, heat would not be supplied, but on the contrary carried off by the exhaust gases. This is prevented by passing the exhaust gases not through the tubes but through a bypass conduit. When the mechanism is controlled with reference to the temperature, this can be effected automatically by means of suitable electronics. When a valve is used, operation is effected automatically depending on the pressure exerted by the exhaust gases.

The form of the reservoir of the apparatus according to the invention is not essential.

Any form is conceivable and in practice the form will be determined by the space available. On board a ship, the apparatus according to the invention can be applied not only in conjunction with the engine, but other engines, such as auxiliary engines, may also be connected to the apparatus. Generally speaking the apparatus may be connected to more than one engine providing hot exhaust gases.

In order to provide a better transfer of heat from the tubes to the surrounding medium, the tubes may be provided with external fins.

It is even better to arrange, transversely to the tubes, one or more steel mats or metal grids in the surrounding medium.

If desired, the tubes in the apparatus according to the invention may have a loop shape.

A satisfactory heat storage material is sand having a maximum particle size of 0.8 mm.

Preferably, fine sand is used having a particle size in the order of 1 60 microns. Owing to the small particle size of sand, very high temperatures can be reached without causing the sand to "pop".

Some embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a cross-sectional view of one embodiment of the apparatus according to the invention; Figure 2 shows a different embodiment of the apparatus according to the invention in cross-sectional view; and Figure 3 shows an embodiment of the apparatus according to the invention provided with a bypass conduit.

The embodiment of the apparatus according to the invention shown in Fig. 1 comprises a reservoir or vessel 1 provided with a supply conduit 2 having a flange 3 at its end, and a discharge conduit 4 having a flange 5 at its end. In the interior of vessel 1, a pair of tube plates 6 and 7 are arranged so that the tube plates and the wall of the reservoir respectively define a header 8 and a header 9.

Header 8 is positioned in vessel 1 directly downstream of supply conduit 2 and header 9 is positioned immediately adjacent to discharge conduit 4.

Extending between tube plates 6 and 7 are a plurality of tubes or pipes 10 secured with their ends in appropriate openings in the tube plates. Pipes 10 form a connection between header 8 and header 9. Pipes 10, which for example, just as vessel 1, consist of steel, are provided with fins 11. The space within the vessel around pipes 10 with fins 11 is filled with sand 1 2 or another suitable heat-storage medium.

In the wall of the reservoir, between tube plates 6 and 7, there is further provided a degassing opening or degassing stub tube (not shown) having a suitable shut-off valve.

Between the finned pipes 10 a plurality of other pipes or tubes 1 3 are embedded in the sand 1 2. Pipes 1 3 are provided with fins 14.

Pipes 1 3 are coupled on one end to a conduit 1 5 passed through the wall of vessel 1, and are coupled at the opposite end to a conduit 16, also passed through the wall of vessel 1.

Mounted in conduit 1 5 outside vessel 1 is a blower 17, which is driven by a motor 18.

Motor 1 8 is, for example, an electric motor suitable for a blower. A suitable medium, for example air, is circulated through tubes 1 3 and conduits 1 5 and 1 6 by means of blower 1 7. Conduits 1 5 and 1 6 respectively form supply and discharge conduits of heat exchanger 19. In heat exchanger 19, the medium supplied and discharged through conduits 1 5 and 1 6 is in heat-exchange contact with a suitable other medium, for example water, which is passed through conduits 20 and 21 to and from the heat exchanger.

Conduits 20 and 21 may, for example, form part of the piping system of a central-heating installation.

Instead of finned pipes, pipes without fins may be used in the apparatus according to the present invention. In that case, transfer of heat from the pipes to the heat-storage material may be promoted by providing metal grids or steel mats arranged transversely to the pipes or tubes, and in contact therewith, in suitably spaced inter-relationship.

The entire reservoir or vessel may be surrounded by an insulating blanket 22, e.g. of glass wool. The reservoir is coupled with an exhaust conduit 23 of an engine not shown.

Exhaust conduit 23 is provided with an expansion member 24, e.g. in the form of a bellows, and has a flange 25 at its end. Conduit 23 is secured with flange 25 to the flange 3 at the end of supply conduit 2 of vessel 1 by means of suitable bolts and nuts 26. In order to minimize the resistance for exhaust gases of the apparatus according to the invention, the diameter of supply conduit 2 should be equal to, or larger than, the diameter of conduit 23. Furthermore, the total cross-sectional area of pipes 10 should be larger than the cross-sectional area of conduit 23. Consequently when the interior diameter of conduit 23 is 15 cm and pipes 10 have an interior diameter of 5 cm, more than 9 pipes should be mounted in the apparatus according to the invention.

Discharge conduit 4 is secured by its flange 4 at its end to the flange 27 at the end of discharge conduit 28, which also includes an expansion member 29. Flanges 5 and 27 are connected together by suitable means, for example, bolts and nuts 30. Conduit 28 serves for discharging the exhaust gases which have given up heat in the apparatus according to the invention.

In the apparatus according to the invention, of which one embodiment is shown in Fig. 1, the exhaust gases which are supplied through conduit 23 and are passed from header 8 through pipes 10 to header 9 and thence discharged through conduit 28, give up heat to pipes 10 and fins 11 on pipes 10, whence heat is transferred to the sand 1 2. During normal operation of, for example, a ship's engine, the sand may reach a high temperature of more than 500,C. The medium circulated in the circuit constituted by conduits 13, 1 5 and 16, for example air, is heated by sand 12 through fins 14 on pipes 13, and transfers the heat collected to water supplied and discharged through conduits 20 and 21 in heat exchanger 1 9. The water may for example be the water in a central heating installation.

Such an installation may be provided with conventional control means such as thermostats and the like, which ensure that heat transporting medium is pumped to heat exchanger 1 9 by blower 1 7 only if required the central heating installation. It is also possible for heat exchanger 1 9 to be coupled directly or indirectly to hot-water supply facilities.

Fig. 2 shows a somewhat modified embodiment of the apparatus according to the invention. Parts of this embodiment equal to parts of the embodiment shown in Fig. 1 are designated by the same reference numerals. The difference from the embodiment of Fig. 1 is that pipes 1 3 and conduits 1 5 and 1 6 have been omitted. Instead, there is provided a conduit 31 extending to heat exchanger 19 and directly connected to header 8. Furthermore there is provided a conduit 32 between heat exchanger 1 9 and header 9. Blower 1 7 is arranged in conduit 31. In operation, if the heat exchanger 1 9 demands heat, the exhaust gas is circulated as a heat transporting medium through conduit 31, heat exchanger 19 and conduit 32.When the engine operates and exhaust gases are supplied through conduit 23 and conduit 2 to header 8, at least a portion thereof will be passed through heat exchanger 19. If no exhaust gases are supplied through conduits 23 and 2, gas is drawn into header 8 through tubes 10 and circulated. Heat exchanger 1 9 is in that case provided with heat from the sand 1 2 around tubes 10, which heat was stored therein earlier after being supplied by the exhaust gases.

Fig. 3 shows an embodiment of the apparatus according to the invention which comprises means for closing the heat storage portion of the apparatus to exhaust gases from the engine to which the apparatus is connected, in case these exhaust gases contain insufficient heat. Parts of the embodiment shown which correspond to parts of the embodiment of Fig. 1 are designated by the same reference numerals. The difference between the apparatus of Fig. 1 and that of Fig.

3 is that a bypass conduit 33 is connected between the supply conduit 2 of vessel 1 and the discharge conduit 4 of vessel 1. During normal operation, when sufficiently hot gases are supplied, these gases are passed predominantly through vessel 1 and not through bypass 33, as the flow resistance of vessel 1 is less than that of conduit 33. Mounted in conduit 2, however, at a point closer to vessel 1 than the point where conduit 33 branches off, is a valve 34. Valve 34, which can be operated by means of a mechanism indicated as a block, is closed in case the temperature of the exhaust gases supplied is too low. The exhaust gases are then bypassed through conduit 33.

Operating mechanism 35 may be any suitable member, such as a servo mechanism controlled in dependence on a temperature measured by a temperature sensor in conduit 2 upstream of valve 34. Alternatively, valve 34 may be provided with a weight in such a manner that at a pre-determined low pressure of exhaust gases supplied the valve is shut by the weight. Mechanism 35 can then be omitted, while the purpose contemplated is achieved all the same. If the engine whose exhaust gases are supplied runs at full capacity, a large amount of high-temperature gas is supplied, whereby the valve is forced into its open position. If the engine runs at a low rate, little gas of a relatively low temperature is supplied, and the valve is forced by the weight into its closed position, while the gas supplied is unable to open the valve.

In the figures, reservoir 1 is shown as a cylindrical vessel. The form of the vessel, and also its position (horizontal or vertical) are not of any essential importance. When the apparatus is used on board a ship, for example, any suitable space can be used for installing the apparatus, and its form may be adapted to the space available.

It is not required that only one engine is connected to the apparatus according to the invention. It is conceivable that a plurality of engines (auxiliary engines and the like) are coupled to the apparatus according to the invention.

In a practically suitable apparatus, in a vessel filled with approximately 2 m3 fine sand having a maximum particle size of 0.8 mm, twenty tubes having an overall length of 5 m per tube were arranged in loop shape.

Each tube had an interior diameter of 22 mm.

When the apparatus was connected to the outlet of a ship's engine in which the exhaust gases had a temperature of 150do, it was found after a certain period of operation that the exhaust gas at the other end of the apparatus had a temperature of 8"C. This proves that virtually all of the heat from the outlet gases was absorbed in the apparatus according to the invention.

Instead of using sand alone as the heatstorage material in the apparatus according to the invention, it is also possible to use, for example, sand admixed with aluminum powder or fine grains or chips of aluminum.

Claims

1. Apparatus for collecting the heat discharged through an exhaust pipe of an engine, in particular a ship's engine, characterized by a reservoir filled with sand or like heat-storage material, a plurality of tubes extending through the reservoir and embedded in the sand, which tubes are at one end in connected with, or adapted to be connected to, the exhaust pipe of the engine, in a suitable manner, and at the opposite end are in connection with, or arranged to be connected to, a conduit for discharge of the engine's exhaust gases transported through the tubes, and means for transporting heat from the reservoir to a remote heat exchanger or other consumer.

2. Apparatus as claimed in claim 1, wherein the tubes extend between two tube plates, which headers being provided between the wall of the reservoir and the respective tube plates, through which headers the exhaust gases of the engine are supplied and discharged, respectively.

3. Apparatus as claimed in claim 2, wherein the means for transporting heat from the reservoir to a heat exchanger or other consumer consist of conduits between each of the headers and the heat exchanger or other consumer, thereby forming a circuit comprising, respectively, the header for supplied exhaust gases, a first conduit, the heat exchanger or other consumer, a second conduit, the header for exhaust gases to be discharged, and the tubes between the headers, there being provided a blower in one of the conduits for passing gases through the circuit.

4. Apparatus as claimed in claim 1 or 2, wherein the means for transporting heat from the reservoir to a heat exchanger or other consumer consist of one or more other tubes embedded in the sand or other heat-storage material, which other tubes are connected on opposite sides respectively to a first and a second conduit connecting the tubes to the heat exchanger or other consumer, in such a manner that the tubes, the first conduit, the heat exchanger or other consumer and the second conduit form a closed circuit, and a blower being provided in said closed circuit for circulating through the circuit a heat-transporting medium which is maintained in said circuit.

5. Apparatus as claimed in claims 1-4, wherein the apparatus is used on board a vessel and the heat exchanger forms part of the vessel's heating system.

6. Apparatus as claimed in claims 1-5, and further comprising a bypass conduit and means for causing at least a portion of the exhaust gases from the engine to bypass the reservoir through said bypass conduit.

7. Apparatus as claimed in claim 6, wherein said means comprise means for measuring the temperature of the exhaust gases supplied and means for diverting the gases from the reservoir to the bypass conduit upon the measurement of a temperature below a selected value.

8. Apparatus as claimed in claim 6, wherein said means comprise a valve mounted in the conduit to the reservoir downstream of the branch-off point of the bypass conduit, which valve is tiltabie so as to shut off the entire conduit, the valve being equipped with a weight arranged relatively to its tiiting axis in such a manner that when a small quantity of gas is supplied the weight keeps the valve in its closed position and when larger amounts of gas are supplied such amounts force open the valve against the weight.

9. Apparatus for collecting the heat discharged through the exhaust pipe of an engine, in particular a ship's engine, substantially as hereinbefore described with reference to Fig. 1, Fig. 2 or Fig. 3 of the accompanying drawings.

10. The features herein described, or their equivalents, in any novel selection.