DEVICE FOR THE DOSED ABSORPTION OF HEAT FROM EXHAUST GASES

Abstract: A device for absorbing heat from hot exhaust gases, in particular aboard a vessel, comprising an evaporator 5 which, via a condensate-supply conduit 9 and a vapor-­ discharge conduit 11, is connected to a condenser 13 through which the medium to be heated flows.

Description: Device for the dosed absorption of heat from exhaust gases The invention relates to a device for the dosed absorption of heat from a hot exhaust gas flow, in particular aboard a vessel. Heating a liquid intended for heating purposes aboard a vessel using a heat exchanger in the engine exhaust conduit, leads in practice to many problems. In particular corrosion due to sulfur condensation occurring on the exhaust-gas side of the heat exchanger causes serious damage to, and even leakage of, such heat exchangers. In order to prevent at reduced heat requirements superheating of the liquid (resulting in a deterioration of the quality thereof and even boiling with considerable increase in pressure), complicated control means are used: on the liquid side, by carrying off the excess heat via a water-cooled dump cooler so that the heat exchanger remains fully loaded but resulting in the danger of sulfur condensate being formed at a partial load of the engine, and on the gas side, by leading the exhaust gases via a valve through a bypass; this measure, however, entails the risk of sulfur condensate being formed at a low heat requirement, especially locally. The object of the invention is to provide a device as described above having a simple construction especially on the exhaust-gas side, which can be easily controlled. To this effect the heat exchanger comprises an evaporator which, via a condensate-supply conduit and a vapor-discharge conduit, is connected to a condenser through which the medium to be heated flows. The highly efficient evaporator can be of a simple and light construction, and the control of the installation can be effected in a simple manner by means of a control valve provided in the condensate conduit. When heat is required, appropriate control means will open said valve to a greater or lesser extent, which is practically immediately followed by the production of vapor which is condensed in the condenser; the condensationheat then being released heats the medium flowing along the condenser. When the valve is closed, all liquid present in the evaporator will evaporate and be subsequently condensed in the condenser, whereupon all liquid present in the installation will be present between the condenser and the control valve. Thus, when no heat is being absorbed, the evaporator will acquire the temperature of the exhaust gases so that no condensate will be formed on the exhaust-gas side. By then dosing - also during full capacity - the supplied liquid and by distributing same effectively over the heating surface, condensation can be prevented completely, obtaining the advantage of a simple construction at the exhaust-gas side. As the system operates in a fully closed circuit the maximum temperature of the heat delivered at the condenser is determined by the specific characteristics of the liquid and the pressure in the circuit. Preferably, the vapor-discharge conduit has an overpressure relief device adapted to said pressure. In a preferred embodiment, the evaporator comprises a vertical cylindrical casing, closed on the underside, the exhaust-gas side having cooling fins provided thereon in a symmetrical arrangement, the inner side being provided with evaporator plates which are in proper heat-conducting contact with the cylinder, above which terminates the condensate-supply conduit. The invention is elucidated with reference to the drawing which diagrammatically shows an embodiment according to the invention. In the figure, the reference numeral 1 denotes the exhaust pipe of a ship's diesel engine, not shown here, which changes into a widened portion 2 which joins the exhaust pipe portion 3 having a regular cross section. The direction of the exhaust gases is indicated by the arrows 4. The widened portion 2 contains an evaporator 5 consisting of a cylindrical casing 6 provided with external fins (not shown) and filled with several superposed evaporator plates 7. These are arranged and provided with openings in such a way that the liquid supplied via the opening 8 located thereabove flows evenly along the entire surface of evaporation. The opening 8 forms the end of a conduit 9 placed in the vapor conduit at a point where the exhaust gases pass, so as to prevent condensate from being formed in this conduit. Apart from the conduit 9 which, as will be still further described, supplies liquid, at point 10 the end of a conduit 11 terminates into the evaporator and this conduit serves to discharge the vapor formed. The conduit 9 ends, at point 12, in a condenser 13 into which, at point 14, terminates the vapor conduit 11. The condenser 13 is not shown in detail, and may be, for example, of a construction known per se having a set of tubes 15 connected between the points 12 and 14. The supply pipe 16 and the discharge pipe 17 of the medium to be heated, in this case being hot water for a vessel, are connected to the condenser. The condensate conduit 9 contains an ON-OFF valve 18 with an exhaust-gas thermostat 19 which puts the apparatus out of operation when there is no or insufficient heat in the exhaust gases. There is further the control valve 20 with the associated sensor 21 controlling the valve 20 as a function of the heat requirement, as well as two valves, 22 and 23, which are provided, respectively, for filing and for dosing of the quantity of liquid in the system. The pressure-relief valve 24 is connected to the vapor conduit 11. The device operates as follows: According to the need for hot water in the circuit 16-17, the valve 20 is more or less opened, When the valve 20 is in the open position, the condensate passes in the direction of the arrow 25 towards the evaporator 5, flows via the opening 8 upon the evaporator plates 7 and is quickly converted into vapor which flows through the conduit 11, in the direction indicated by the arrow 26, to the condenser 13. The vapor is condensed herein. The condensation heat being released heats the water flowing in the circuit 16-17. Opening the valve 20 more or less by means of a control means 21 not further specified, makes it possible to control the water temperature quickly and accurately. When the desired temperature is reached the valve 20 closes, and all the liquid present past the valve 20 will evaporate in the evaporator, which is 'heated dry', is subsequently condensed in the condensorand stored in the condensate conduit 9 before the valve 20 so as to be ready for immediate use.

Claims: Claims: 1. A device for the dosed absorption of heat from a not exhaust gas flow using a heat exchanger (2) provided therein, in particular aboard a vessel, characterized in that said heat exchanger (2) consists of an evaporator (5) which, via a condensate-supply conduit (9) and a vapor-discharge conduit (11), is connected to a condenser (13) through which the medium to be heated flows. 2. A device according to claim 1, characterized by a control valve (18) in the condensate conduit (9). 3. A device according to claim 1 or 2, characterized in that the evaporator (5) comprises a cylindrical, verticcl casing (6) closed on the underside and with cooling fins on the exhaust-gas side, evaporator plates (7) being provided in heatconducting contact with the outer wall (6), above which the condensate-supply conduit (8) terminates. 4. A device according to claims 1-3, characterized in that the vapor-discharge conduit (11) is connected to an overpressure relief device (24). 5. A device according to claims 1-4, characterized in that the terminal part (8) of the condensate-supply conduit (9) is positioned in the vapor-discharge conduit (11) in such a way that there is at no point direct contact between the exhaust gases and the condensate conduit (8).

Inventors: VAN DER ZANDE, CHRISTOFFEL ADRIANUS
Applicants: B.V. V/H. GEBR. DE HAAN
Application year: 1984
Main classification: F02G5
IPC codes: F02G5, F22B1