FR2465888A1 - DEVICE FOR RECOVERING THE HEAT EXHAUSTED FROM THE EXHAUST PIPE OF AN ENGINE - Google Patents

Abstract

DEVICE FOR RECOVERING THE HEAT DISCHARGED BY THE EXHAUST PIPE OF AN ENGINE, IN PARTICULAR FROM A SHIP ENGINE, CHARACTERIZED IN THAT IT INCLUDES: A TANK 1 FILLED WITH MATERIAL CAPABLE OF STORING HEAT, SUCH AS SAND 12; A PLURALITY OF TUBES 10 EXTENDING THROUGH ITS TANK AND FLOODED IN THE SAND, THESE TUBES BEING CONNECTED, BY ANY APPROPRIATE MEANS, TO ONE END OF THE EXHAUST PIPE 23 OF THE ENGINE, AND, AT ITS OTHER END, TO A DUCT 28 TO EVACUATE THE EXHAUST GAS FROM THE ENGINE HAVING PASSED THROUGH THE SAID TUBES, AND FROM MEANS FOR TRANSPORTING THE HEAT FROM TANK 1 TO A REMOTE SYSTEM CONSUMING THE RECOVERED CALORIFIC ENERGY, IN PARTICULAR A HEAT EXCHANGER 19.

Description

This invention relates to a device for recovering heat

  discharged through the exhaust pipe of an engine, especially a ship's engine. We know that heat is generated during engine operation. In general, a large part of this heat is evacuated with the exhaust gases and fumes, without being used. An object of the present invention is to provide a device which collects at least part of the

  heat, which would otherwise be removed without being used.

Consequently, the invention relates to a device for recovering heat, characterized in that it comprises a tank filled with sand or any other material capable of storing heat, a plurality of tubes extending through the tank and embedded in sand, these tubes being, by one of their ends, connected, or adapted to be able to be connected, in a suitable manner to the exhaust pipe of the engine and being, by their other end, connected, or adapted to be able to be connected , to one

pipe to evacuate the exhaust gases from the engine transported through

to tubes, and means for transporting heat from the reservoir to a

heat exchanger or other remote consumer system.

  In the device according to the present invention, a major part of

the heat, which otherwise is removed with the exhaust gases and per-

due to the atmosphere, is transferred through the sand tubes or the appropriate heat storage medium that surrounds the tubes. During normal operation of an engine, such as a ship's engine, the

sand can thus reach a high temperature, possibly reaching sensible-

500'C. The heat stored in the sand can be extracted from it.

different ways.

  According to one embodiment of the device according to the invention, the tubes extend between two tubular plates; collectors are provided between the wall of the tank and the respective tubular plates, through which the engine exhaust gases are respectively brought and discharged; and

the means for transporting heat from the reservoir to a heat exchanger

  heat exchanger or another user system consist of conduits between each of the collectors and the exchanger or other user system, so as to form a circuit comprising respectively the manifold for the exhaust gases delivered, a first conduit, the exchanger heat or other user system, a second pipe, the collector for the exhaust gases to be evacuated, and the tubes between the collectors, a fan being provided in one of the pipes to circulate the gases through said circuit.

  According to another embodiment of a device according to this invention

  tion, the means for transporting heat from the tank to a heat exchanger or to another consumer system comprise one or more other tubes embedded in the sand, or in any other storage material

heat, these other tubes being connected, by their opposite sides, res-

  pectively on a first and a second pipe connecting the tubes to the heat exchanger or to any other consumer system, so that the tubes, the first pipe, the heat exchanger and the second pipe constitute a closed circuit, a fan being provided in said closed circuit for circulating therein a heat transfer medium or medium which is

maintained in this circuit.

In the heat exchanger or in any other consumer system

heat energy part of the device 1 according to the invention, or which is coupled to this device, the heat is, for example, transmitted to the water

  a heating system or a system supplying hot water.

When applied on board ships, the device according to the pre-

  sente invention makes unnecessary a conventional central heating installation, which allows a substantial energy saving. Given

  that the sand has a high heat capacity, even when the mo-

  tor is stopped and the heat ceases to be supplied, a time elapses

  relatively large before all the heat stored in the dis-

positive according to the invention is dissipated. On board a ship, it is therefore pos-

  may continue to operate the central heating system for a considerable time after the engine has stopped. This is particularly important in the case of ships carrying flammable liquids, such as petroleum and the like. In order to avoid explosions, no "open fire" should exist on board such ships during loading and unloading operations, which means that in addition to the engine, a central heating installation operating, for example, with a liquid fuel burner, must also be stopped. Most of the time, this causes discomfort for the crew, especially when loading operations

and unloading take considerable time. This drawback disappears

arises when the device according to the present invention is used in an ins-

central heating tallation. The tubes of the device according to the invention can be made of steel,

that is, from the same material as the engine exhaust pipe.

According to a preferred embodiment of the device according to this invention, the latter comprises a bypass and means for causing the 0 a-: motor exhaust to pass, in whole or in part, outside

  had reservoir through said bypass. These means can include

  take means to measure the temperature of the exhaust gases

  liv: rs, and means for diverting the gases coming from the tank towards the bypass, when a temperature is measured below a value chosen in advance. These means can also include a valve rorntee in the conduit going to the tank, downstream from the point where the branch line is connected; this valve is actuated so as to

  obstruct the entire line, and it is equipped with a weight arranged in such a way

  ccn with respect to its point of articulation that, when a small quantity of gas is delirium, the weight keeps the valve in closed position, and that, when larger quantities of gas are delivered, the valve opens

against the action of weight.

  When the engine is running slowly, the heat emission is relatively

  relatively low, and the exhaust gases have a relatively low temperature.

  tively weak. LDsque exhaust gases with such a temperature

low erasure pass through the device in which the sand is at a temperature

  relatively higher ture, heat is not delivered to the sand, but on the contrary, it is evacuated by the exhaust gases. This drawback is avoided by passing the exhaust gases not through the tubes,

  but through a diversion. When the mechanism is con-

  controlled by reference to temperature, this control can be performed automatically

  using appropriate electronic circuits. When using a valve, the operation is automatic, depending on the pressure

  exerted by exhaust gases.

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The shape of the reservoir of the device according to the invention is not critical.

  Any form is conceivable, and in practice it will be determined by the

available space. On board a ship, the device according to the present invention can be applied not only in combination with an engine, but all other engines, such as the auxiliaries on board, can be connected to the device. In general, the device according to this invention can be

connected to more than one engine producing hot exhaust gases.

  In order to obtain better heat transfer from the tubes to the surrounding environment, the tubes can be provided with external fins. It is even preferable to provide, transverse to the tubes, one or more

steel flakes, or metallic grids, in the surrounding environment.

If desired, the tubes of the device according to the present invention

  may have the appearance of a loop.

  A suitable heat storage material consists of a

  sand with a maximum particle size of 0.8 mm. Preferably, we use

  reads fine sand with a particle size of the order of 1 60 microns.

  Given the small particle size of the sand, we can reach very

  high temperatures without the risk of the sand rising.

  Other features and advantages of this invention will emerge

  of the description given below, with reference to the attached drawing, which illustrates

various non-limiting examples of embodiment. In the drawings:

  - Figure 1 is a sectional view of a first embodiment

  tion of a device according to the invention; - Figure 2 illustrates, in section, a second embodiment of a Z5 device according to the invention; and, - Figure 3 illustrates the variant of the device of the invention provided

of a derivation.

  The embodiment of the device according to the invention shown in

  Figure 1 comprises a closed enclosure, or reservoir 1, provided with a

  feed line 2 provided with a collar 3 at its end, and a

  discharge pipe 4 provided with a collar 5 at its end. We say-

poses, inside the enclosure 1, a pair of tubular plates 6, 7, so that these tubular plates and the wall of the tank delimit

  respectively a collector 8 and a collector 9. The collector 8 is posi-

  in the enclosure 1, directly downstream of the supply line 2,

  and the manifold 9 is positioned in the immediate vicinity of the evacuation pipe.

cuation 4.

  A plurality of tubes or pipes 10 extend between the tubular plates

  6 and 7, these tubes having their ends fixed in appropriate openings of the tube plates. The tubes 10 form a connection between the collector 8 and the collector 9. The tubes 10, which are for example made of steel, like the enclosure 1., are provided with fins 11. The space surrounding the tubes 10 and their fins 11, in enclosure 1, is filled with sand 12 or

any other appropriate means or medium which can store heat.

  In the wall of the tank between the tubular plates 6 and 7, there is provided a degassing opening or a section of degassing tube (not shown) comprising a suitable closing valve. A plurality of tubes or pipes 13 are immersed in the sand 12 between the tubes 10 provided with fins. The tubes 13 are also provided with fins 14. The pipes 13 are coupled, at one end, to a pipe 15 which passes through the wall of the enclosure 1, and they are coupled, at their opposite end, to a pipe 16 which also passes through the wall of the enclosure 1. A fan 17, driven

  by a motor, is mounted in a pipe 15, outside the enclosure 1.

  The motor 18 is, for example, an electric motor. A suitable medium, such as air, for example, circulates through tubes 13 and pipes 15 and

  16, under the effect of the fan 17. -The conduits 15 and 16 constitute respec-

the supply and exhaust ducts of the heat exchanger

19. In this exchanger, the medium delivered and evacuated respectively by the

  intermediate of the conduits 1 5 and 1 6 is in heat exchange contact with another suitable medium, for example water, which passes through the conduits 20 and 21 going towards the exchanger and coming from this exchanger, respectively. The

  conduits 20 and 21 may, for example, be part of the piping system

tion of a central heating installation.

  Tubes without fins can be used in place of the fin tubes, in the device according to the invention. In this case, the transfer of heat from the tubes to the material storing the heat can be initiated by providing metal grids or steel flakes arranged transversely to the tubes or pipes, and in contact with the latter, these grids or flakes being

  spaced from each other appropriately.

  The entire tank or enclosure 1 may be surrounded by a

  insulating lining 22, for example made of glass wool. The tank is connected

  strung on an exhaust pipe 23 of an engine, not shown. The exhaust pipe 23 is provided with an expansion chamber 24, having for example

  the shape of bellows, and it has a flange 25 at its end. The con-

  pick 23 is fixed, by its flange 25, to the flange 3, at the end of the supply line 2 of the enclosure 1, by means of screws or nuts

26. In order to minimize resistance to exhaust gases

  ment of the device according to the invention, the diameter of the supply line

tion 2 must be equal to or greater than the diameter of the pipe 23. Furthermore, the total area of the cross section of the tubes 10 must be greater than the area of

the cross section of the pipe 23. Consequently, when the diameter in-

  dull line 23 is equal to 15 cm, and that the tubes have a diameter

1 5 meter internal 5 cm, more than nine tubes can be mounted in the dispo-

sitive according to the invention.

  The discharge pipe 4 is fixed, by its flange 5, to the flange 27, at the end of the discharge pipe 28, which also includes an expansion chamber 29. The flange 5 and the flange 27 are fixed l 'one to

  the other by any appropriate means, such as, in particular, screws and nuts 30.

  Line 28 is used to evacuate the exhaust gases which have abandoned their

  heat in the device according to the invention.

  In the exemplary embodiment of the invention shown in Figure 1, the exhaust gases, which are delivered via line 23, and which pass from the manifold 8, through the tubes 10, to the manifold 9, to then be evacuated through line 28, communicate their heat to the tubes 10 and to the fins 11, which realizes the transfer of this heat to the sand 12. During the normal operation of an engine, such as, for example , a ship's engine, the sand can reach a high temperature, over 500'C. The medium which circulates in the circuit constituted by the conduits 13, 15 and 16, for example air, is heated by the sand 12 via the fins 14 on the tubes 13, and it transfers the heat collected to the water supplied and discharged respectively through the conduits 20 and 21 of the heat exchanger 19. The water can be, for example, that of a central heating installation. Such an installation can be provided with

  conventional command and control means, such as thermostats and si-

  milaires, which ensure that the heat transfer medium is pumped to the heat exchanger 19, by the fan 17, only when required by the central heating installation S. The heat exchanger 19 can also be connected

directly or indirectly to a hot water supply installation.

Figure 2 illustrates a variant of the invention. In this figure, the same references have been made for components similar to those of the embodiment described above; with reference to Figure 1. This! 0 ': ariante differs from the first embodiment in that it does not include are you ..- S 1 3 and the conduits 15 and i16. 31 etc: in front of the thermal changer 19, which is directly connected to the collector 8. Furthermore, the device comprises a pipe 32 arranged

between the heat exchanger 19 and the collector 9. The fan 17 is

  laid in line 31. During operation, when the heat exchanger 19 lerman-de c '; their, the exhaust gases serving as heat transfer medium circulate in line 31, heat exchanger 19 and line 32. When the ramoteur is in operation and that exhaust gases are delivered in

  the conduits 23 and 2, towards the manifold 8, at least part of these gases pass through

pours the exchanger 19. If no part of the exhaust gas crosses the coriduits 23 and 2, the gas is sucked into the manifold 8 through the tubes 10, and it is circulated. In this case, the heat exchanger 1 9 is supplied with heat energy from the sand 12 around the tubes, this heat having been stored before after having been brought by

the exhaust gas.

  Figure 3 illustrates yet another exemplary embodiment of a dis-

  positive according to the invention, which comprises means for closing the part of

heat storage of the device to exhaust gases from the engine

  tor to which this device is connected, in the / as o these exhaust gases do not contain enough calories. Here again, the same references have been made to the components identical to those of the embodiment shown in Figure 1. The difference between the device shown in Figure 1 and that illustrated in Figure 3 is that a bypass 33 is connected between the supply line 2 of the enclosure 1 and the discharge line 4 of the same enclosure. During normal operation, when the quantity of hot gases delivered is sufficient, these gases pass through

  predominantly enclosure 1, and they do not flow through the drift

  tion- 33, since the resistance to flow, in enclosure 1, is lower than that of line 33. In line 2, at a location closer to enclosure 1 than the point o connects line 33, a valve 34 is provided. This valve 34, which can be actuated and controlled

  by a mechanism shown schematically by block 35, is closed when the temperature

  the exhaust exhaust gas supply is too low; the exhaust gas

  are then diverted through line 33.

The control mechanism 35 can be of any known type, such as, in particular, a servo-rrechanism, controlled as a function of a ter.perature measured by a temperature detector placed in the pipe Z, upstream of the valve 34. As a variant, this valve 34 can be provided with a weight, so that the valve is maneuvered when closed by the weight, for a

  predetermined low exhaust gas pressure. In this case, the me-

control mechanism 35 can be deleted, the desired result being then achieved. If the exhaust gas engine is running at full speed, a large amount of high temperature gas is delivered, which keeps the valve in its fully open position. When the engine is running at low speed, little gas at a relatively low temperature is delivered, and the valve is held by the weight in the closed position,

the gases delivered do not allow its opening.

  In the drawings, the reservoir 1 has been shown in the form of a

cylindrical enclosure. The shape of this enclosure, as well as its position (hori-

  zontal or vertical), are not of essential importance. When the device is used on board a ship, for example, any suitable space can be used to install the device, and the shape of the device can

  be adapted to the space available.

  The invention is not limited to a device connected to a single motor

  we can indeed consider coupling a plurality of motors (auxiliary motors

  liaries and others) of the device according to the invention.

  The following example, which is of course not limiting,

illustrates the invention.

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In an enclosure filled with approximately 2 m3 of fine sand having a maximum particle size of 0.8 mm, twenty tubes were laid, in a loop, with a total length of 5 m per tube. Each tube has an internal diameter of 22 mm. When the device is connected to the exhaust gas outlet of a ship engine having a temperature of 1500C, it has been found, after a certain period of operation, that the

  exhaust gases, at the other end of the device, exhibited a tem-

80C temperature. This proves that practically all the heat provided by

the exhaust gas is absorbed in the device according to the invention.

Instead of using sand alone as a material which stores heat, in the device according to the invention, it is also possible to use, for example, sand mixed with aluminum powder or fine grains, or

aluminum shavings.

  It remains to be understood that this invention is not limited to the embodiments described and shown, but that it encompasses

all variants.

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Claims (6)

  1 - Device to recover the heat dissipated by the exhaust pipe-   pement of an engine, in particular of a ship engine, characterized in that it comprises: a tank (1) filled with a material capable of storing heat, such as sand (12); a plurality of tubes (10) extending in said reservoir and embedded in the sand, these tubes being connected, by any suitable means, to one end of the engine exhaust pipe (23),   and, at its other end, to a pipe (28) for evacuating the exhaust gases pement of the motor having passed through said tubes, and means for trans-   heat from the tank (1) to a remote system consuming mant the heat energy recovered, in particular a heat exchanger (19).   2 - Device for recovering heat according to claim 1, characterized in that the tubes extend between two tubular plates (6, 7) and in that it comprises two collectors (8, 9) positioned between the wall of the tank and the respective tube plates, through which the gases   engine exhaust are respectively delivered and evacuated. 3 - Device according to claim 2, characterized in that the means for transporting heat from the tank to a heat exchanger (1 9) or to another system consuming energy include   pipes (15,16 - 31,32) between each of the collectors (8, 9) and the sample   heat sink (19) or the system consuming energy, which forms a circuit which comprises, respectively: the manifold (8) for the exhaust gases delivered, a first pipe (15 - 31), the exchanger heat or equivalent (19), a second pipe (16 - 32), the manifold (9) for the exhaust gases to be evacuated, and the tubes (10) between the collectors, a fan (17) being provided in the one of the lines to force the gases to pass through said circuit. 4 - Device according to one of the preceding claims, characterized in that the means for transporting the heat from the tank (1) to that in the heat consuming system, such as the heat exchanger (19), comprise one or more other tubes (13) embedded in the sand (12) or other medium storing the heat, these other tubes being connected, by their opposite sides, respectively to the first (15) and the second (16)   pick connecting the tubes to the exchanger, so that the tubes, the first 1! pipe, the heat exchanger and the second pipe form a closed circuit, a fan (17) being provided in said closed circuit to ensure the circulation in this circuit of a heat transfer medium which is maintained there.   - Device according to one of claims 1 to 4, characterized in that   that it is used on board a ship, and that the heat exchanger does   part of the nayire heating installation.   6 - Device according to one of claims 1 to 5, characterized in that   that it includes a bypass line (33) and means (34-35) for supplying at least part of the exhaust gases from the engine to avoid the tank through said line (33). 7 - Device according to claim 6, characterized in that said   : -y-s <r: .pr enn :. means for measuring the temperature of the exhaust gases   penrmes d: d Cvréset these! means to divert these gases from the tank to the d.rivation, when the measured temperature falls below a i 5 determinate value.   - Dispostifl according to claim 6, characterized in that said means comprise a valve (34) mounted in the pipe (Z) leading to the tank, downstream from the branch point of the bypass (33), this valve being able to be actuated so as to completely close off all of the   Z0 pick (2), and in that said valve (34) is equipped with a weight which is arranged, relative to its axis of articulation, so as to keep the valve in posi- closing when a small amount of gas is delivered, the valve opening fully, against the action of the weight, when large   quantities of gases are delivered, under the effect of the pressure of these gases.