Technical field

[001 ] Invention relates to a cooling arrangement for a combined cycle internal combustion piston engine power plant comprising an internal combustion piston engine and a boiler system connected to receive heat produced in the internal combustion piston engine according to preamble of claim 1 .

Background art

[002] EP1028233 A2 discloses a combined cycle power plant, comprising at least one multi-cylinder combustion engine unit, the exhaust gases of which are fed into exhaust gas boiler producing steam. The steam is utilized in a steam turbine to produce electricity. The arrangement also comprises a steam turbine, to which an electric generator, a condenser, a heat exchanger, which may be utilized for cooling of the engine, and a feed water tank are attached. [003] Thus, a combined cycle power plants utilizing internal combustion engines are known as such. Such a power plant produces electricity by means of both an engine coupled generator and a steam turbine generator driven by steam produced by the heat of the exhaust gases of the engine.

[004] In prior art combined cycle power plants there is an exhaust gas boiler ar- ranged in connection with the exhaust gas channel of the engine. The steam generated is led to a steam turbine which is arranged to drive a generator to produce electricity. Steam used in the steam turbine at lower pressure is normally condensed by a condensing unit transferring heat to the surrounding. [005] It is an object of the invention to provide a cooling arrangement for a combined cycle internal combustion piston engine power plant by means of which the heat flows of the arrangement may be efficiently controlled.

Disclosure of the Invention

[006] Objects of the invention are substantially met by a cooling arrangement for a combined cycle internal combustion piston engine power plant comprising an internal combustion piston engine and a boiler system connected to receive heat produced in the internal combustion piston engine comprising a turbine-generator set, which cooling arrangement comprises a cooling fluid circuit provided with a first heat transfer arrangement adapted to cool the fluid in the cooling fluid circuit, and a second heat transfer arrangement for receiving heat from the engine, a condenser heat transfer arrangement for condensing the steam in the boiler system and a third heat transfer arrangement for receiving heat from the engine. It is characteristic to the invention that the first heat transfer arrangement, the second heat transfer arrangement, the condenser heat transfer arrangement and the third heat transfer arrangement are all connected in series to the cooling fluid circuit.

[007] According to an embodiment of the invention the cooling fluid circuit of the heat transfer arrangement is a closed circuit. [008] According to another embodiment of the invention the first heat transfer arrangement is arranged to transfer heat from the cooling fluid to the air surrounding the arrangement without mass transfer to the air.

[009] The third heat transfer arrangement for receiving heat from the engine may be applied in practice making use of various possible ways of connecting the en- gine to the cooling arrangement.

[0010] According to still another embodiment of the invention the second heat transfer arrangement is arranged to transfer heat from the combustion air of the engine to the cooling fluid in the cooling fluid circuit. [001 1 ] According to still another embodiment of the invention the condenser heat transfer arrangement is arranged to condense the steam in the boiler system and transfer heat to the cooling fluid in the cooling fluid circuit arranged downstream the second heat transfer arrangement. [0012] According to still another embodiment of the invention the condenser heat transfer arrangement is arranged parallel with the second heat transfer arrangement.

[0013] According to still another embodiment of the invention the third heat transfer arrangement comprises lubrication oil heat transfer unit, combustion air heat transfer unit and an engine jacket heat transfer unit connected in series to the cooling fluid circuit.

[0014] According to still another embodiment of the invention the third heat transfer arrangement comprises lubrication oil heat transfer unit, combustion air heat transfer unit and an engine jacket heat transfer unit connected parallel to the cooling fluid circuit.

[0015] According to still another embodiment of the invention the second heat transfer arrangement is provided with a temperature control system to control the heat transfer rate from the combustion air to the cooling fluid. [0016] According to still another embodiment of the invention the third heat transfer arrangement is provided with a temperature control system to control the heat transfer rate from the combustion air, lubrication air and engine to the cooling fluid.

[0017] According to still another embodiment of the invention the cooling arrangement comprises a pre-heater heat transfer arrangement connected at its first side to the cooling fluid circuit downstream the third heat transfer arrangement and that the pre-heater heat transfer arrangement is connected at its second side to the boiler system, downstream the condenser heat transfer arrangement to transfer heat from the cooling fluid to the condensate thus pre-heating the condensate. In this case the pre-heater is an engine dedicated pre-heater. [0018] According to still another embodiment of the invention the arrangement comprises a set of first heat transfer arrangements comprising more than one first heat transfer arrangements connected in parallel.

[0019] According to still another embodiment of the invention the arrangement comprises a set of second heat transfer arrangements comprising more than one second heat transfer arrangements connected in parallel, each of the second heat transfer arrangements arranged to receive heat from separate engine, and the arrangement comprises a set of third heat transfer arrangements comprising more than one third heat transfer arrangements connected in parallel, each of the third heat transfer arrangements arranged to receive heat from a separate engine.

[0020] According to still another embodiment of the invention the set of first heat transfer arrangements is connected via a first manifold to the set of second heat transfer unit so that a first selected number of the first heat transfer arrangements may operated i.e. be in use and a second selected number of the second heat transfer arrangements may operated.

[0021 ] According to still another embodiment of the invention the set of second heat transfer arrangements is connected to a condenser heat transfer arrangement via a second manifold so that cooling fluid heated in the second selected number of the second heat transfer arrangements may led to the condenser heat transfer arrangement.

[0022] According to still another embodiment of the invention the condenser heat transfer arrangement is connected via a third manifold to the set of third heat transfer arrangements so that cooling fluid heated in the condenser heat transfer arrangement may be led to the third selected number of the third heat transfer ar- rangements.

[0023] By means of the invention the steam turbine output may be maximized and plant parasitic load minimized. Additionally by means of the present invention the water consumption is minimized particularly compared to using cooling towers. One additional benefit for this solution, compared to conventional cooling towers and air cooled condensers, is that the optimal performance is guaranteed also in extremely low temperature ambient conditions as cooling fluid may be selected suitably for the circumstances, e.g. use of anti-freeze solution is possible in the cooling circuit. Additionally the solution requires a smaller plant footprint compared to using a cooling tower and air cooled condenser solutions. Brief Description of Drawings

[0024] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in which

- Figure 1 illustrates a combined cycle internal combustion piston engine power plant according to an embodiment of the invention,

- Figure 2 illustrates a combined cycle internal combustion piston engine power plant according to another embodiment of the invention,

- Figure 3 illustrates a combined cycle internal combustion piston engine power plant according to still another embodiment of the invention,

- Figure 4 illustrates a combined cycle internal combustion piston engine power plant according to another embodiment of the invention, and,

- Figure 5 illustrates a combined cycle internal combustion piston engine power plant according to another embodiment of the invention. Detailed Description of Drawings

[0025] Figure 1 depicts schematically a combined cycle internal combustion piston engine power plant 10. The combined cycle power plant comprises an internal combustion engine 100 and a boiler system 200 connected with each other. An exhaust gas channel 102 is in connection with the boiler system 200 so that the exhaust gas from the engine is cooled down in the boiler and steam is produced by means of the heat in the exhaust gas.

[0026] The boiler system 200 comprises a steam production unit 202, steam tur- bine - generator set 204, condenser heat transfer arrangement 206, condensate preheater 208 and a feed water tank 210, and a piping 212 with a circulating pump 214 connecting them and forming a cycle process. The steam production unit 202 comprises e.g. one or more economizer 202.1 , one or more evaporator 202.2 and one or more super heater 202.3 and one or more steam drum 202.4 arranged in a manner known as such.

[0027] The internal combustion engine 100 may be an engine known as such. Typically such an engine needs to be provided with a system by means of which heat may be transferred away from the engine. Due to the operation of the present invention said system is divided to a lower temperature level heat transfer arrangement 104 and to a higher temperature level heat transfer arrangement 106. The engine is couple to an electric generator 108. Advantageously the lower tem- perature level heat transfer arrangement 104 is adapted to cool the combustion air of the engine. The higher temperature level heat transfer arrangement 106 advantageously is adapted to cool the lubrication oil, engine jacket and also partly the combustion air. The engine is mechanically coupled to an electric generator 108 [0028] The combined cycle power plant is provided with a cooling arrangement 12 common to the boiler system and the internal combustion engine 100. The cooling arrangement 12 comprises a cooling fluid circuit 20 provided for transferring heat between at least the engine 100 and the boiler system 200. The cooling arrangement 12 is provided with a first heat transfer arrangement 14, which is adapted to cool the fluid in the cooling fluid circuit 20. The first heat transfer arrangement 14 may be realized in various manners as long as it may extract heat from the cooling fluid in such a manner that no mass transfer of the cooling fluid will take place. Preferably the first heat transfer arrangement 14 is so called radiator in which the cooling fluid is cooled by transferring heat to the surrounding air. The cooling liquid is led to the first heat transfer arrangement 14 at its highest temperature in the circuit 20 and is cooled down to the lowest temperature. The circulation of the cooling liquid is maintained by means of a pump 17, 19 or alike.

[0029] Next in the cooling fluid circle, the cooling arrangement 12 comprises, downstream from the first heat transfer arrangement 14, a second heat transfer arrangement 16 for receiving heat from the engine. The second heat transfer arrangement 16 is preferably arranged in connection with the lower temperature level heat transfer arrangement 104 of the engine, cooling the combustion air of the engine 100 by transferring heat from the combustion air of the engine to the cooling fluid in the cooling fluid circuit 20. In the figure 1 there is shown an engine driv- en pump 19 to facilitate the fluid flow through the second heat transfer arrangement 16. The second heat transfer arrangement 16 is provided with a by-pass 17 with a pump by means of the maximum cooling capacity for the condenser heat transfer arrangement 206 may be secured. [0030] After the second heat transfer arrangement 16 there is the condenser heat transfer arrangement 206 of the boiler system 200 arranged in the circuit 20. At this stage of the circuit 20 the cooling fluid receives heat from the steam condensing in the condenser heat transfer arrangement 206. The further heated cooling fluid is next led to a third heat transfer arrangement 18 arranged in the circuit 20. The third heat transfer arrangement 18 is arranged to transfer heat from the engine, particularly from the lubrication system, engine jacket and combustion air, to the cooling fluid.

[0031 ] In the embodiment of the figure 1 there is also a pre-heater heat transfer arrangement 208 operating as the condensate pre-heater 208. The pre-heater heat transfer arrangement 208 is at its second side to the boiler system 200 downstream the condenser heat transfer arrangement 206 to transfer heat from the cooling fluid to the condensate thus pre-heating the condensate. The pre-heater heat transfer arrangement 208 is here connected to the engine jacket cooling system to receive heat from the cooling fluid to the condensate via an engine jacket heat transfer unit.

[0032] The common cooling fluid circuit 20 is thus provided with heat transfer arrangements cooling the engine 100 and condensing the steam of the boiler system. The first heat transfer arrangement 14, the second heat transfer arrangement 16, the condenser heat transfer arrangement 206 and the third heat transfer ar- rangement 18 are all connected in series to the cooling fluid circuit 20. Additionally, the cooling fluid circuit 20 of the heat transfer arrangement 10 is a closed circuit. It should be noted that in this connection the third heat transfer arrangement 18 stands for one or more heat exchangers transferring heat from or to the engine which may be specified case by case. The ways of connecting such heat ex- changers of the engine in heat transfer communication with the common fluid circuit 20 may be selected according to a specific application and are apparent to those skilled in the art. . [0033] Figure 1 illustrates also a temperature control system 1 10 in the second heat transfer arrangement 16 provided to control the heat transfer rate of the second heat transfer arrangement 16 from the combustion air to the cooling fluid. There is also a temperature control system 1 12 in the third heat transfer arrange- ment 18 provided to control e.g. the heat transfer rate from the combustion air, lubrication air and engine to the cooling fluid.

[0034] In figure 2 there is shown another embodiment of the invention. It and its operation differs from that shown in figure 1 by following features. In this embodi- ment the second heat transfer arrangement 16 comprises an intermediate circuit so that the cooling fluid circuit 20 is physically separated from the engine. The third heat transfer arrangement 18 comprises separate heat transfer arrangements for lubrication oil, combustion air and engine cooling i.e. lubrication oil heat transfer unit 18.1 , combustion air heat transfer unit 18.2 and an engine jacket heat transfer unit 18.3 connected in series to the cooling fluid circuit 20. The circulation of the cooling liquid is maintained by means of a pump 20 or alike. There is also a temperature control system 1 12.1 , 1 12.2, 1 12.3 to independently control the heat transfer rate from the combustion air, lubrication air and engine to the cooling fluid. [0035] Figure 3 illustrates a further embodiment of the invention. In this embodiment the cooling arrangement 10 comprises a set of first heat transfer arrangements 14'. The more than one first heat transfer arrangements 14 are connected in parallel. The actual number of the first heat transfer arrangement is selected based on required cooling capacity and only two units are shown here for clarity reasons.

[0036] The arrangement further comprises a set of second heat transfer arrangements 16' comprising more than one second heat transfer arrangements 16 also connected in parallel. Each of the second heat transfer arrangements is preferably arranged to receive heat from separate engine. Thus the number of the second heat transfer arrangements corresponds to the number of engines coupled to the cooling arrangement. The second heat transfer arrangement may be realized according to a specific application and are apparent to those skilled in the art. Additionally the arrangement comprises a set of third heat transfer arrangements 18' comprising more than one third heat transfer arrangements 18 connected in paral- lei. Correspondingly each of the third heat transfer arrangements 18 is arranged to receive heat from a separate engine and the number of the third heat transfer arrangements 18 corresponds to the number of engines couple to the cooling arrangement. For clarity reason there are only two engines 100 and respective heat transfer arrangement 16, 18 shown in the figure 3.

[0037] There is a first manifold 24 provided in the arrangement connecting the set of first heat transfer arrangements 14' to the set of second heat transfer unit 16' so that a first selected number of the first heat transfer arrangements 14 may operated and a second selected number of the second heat transfer arrangements 16 may operated. In practice the first manifold makes it possible to select the number of the first heat transfer arrangements in operation independently from engines in operation. Cooling fluid is also subjected to mixing in the first manifold which evens the temperature differences in the cooling fluid when flowing into the second selected number of the second heat transfer arrangements 16. Further there is a second manifold 26 by means of which the set of second heat transfer arrangements 16' is connected to the condenser heat transfer arrangement 206. Thus the cooling fluid heated in the second selected number of the second heat transfer 16 arrangements may be led to the condenser heat transfer arrangement 206. In the figure 3, there is shown only one condenser heat transfer arrangement 206 in the boiler system, but the arrangement may be provided with several condenser heat transfer arrangements 206. Additionally, the arrangement comprises several boiler systems 200 common. Preferably each engine 100 is provided with a dedicated boiler system which is arranged to feed steam to a common steam turbine - generator set 204.

[0038] The condenser heat transfer arrangement 206 is in turn connected via a third manifold 28 to the set of third heat transfer arrangements 18' so that so that cooling fluid heated in the condenser heat transfer arrangement may led to the third selected number of the third heat transfer arrangements 18.. A return pipe 32 is arranged connect the condensate pre-heater 208 from its outlet to a fourth manifold 34 which closes the circuit being connected to inlets of the first heat transfer arrangements 14. There are also by-pass channels 25, 27, 29, provided in the arrangement, between the manifolds 24,26 and 28,32 respectively in order to control the cooling fluid flow in the arrangement. The by-pass channels are provided with means for controlling the fluid flow via the bypass channels. Preferably the means for controlling the fluid flow comprises a pump and/or a control valve

[0039] In order to set the first, second and the third selected number of heat transfer arrangement in operation the arrangement is provided with control means (not shown) in connection with each heat transfer arrangement.

[0040] Figure 4 depicts schematically a combined cycle internal combustion piston engine power plant 10 similar to that in figure 1 except that the condenser heat transfer arrangement 206 is arranged to condense the steam in the boiler system and transfer heat to the cooling fluid in the cooling fluid circuit 20 arranged parallel with the second heat transfer arrangement 16.

[0041 ] Figure 5 illustrates a further embodiment of the invention. It show schematically a combined cycle internal combustion piston engine power plant 10 similar to that in figure 2 except that the third heat transfer arrangement 18 comprises lubrication oil heat transfer unit, combustion air heat transfer unit and an engine jacket heat transfer unit connected parallel to the cooling fluid circuit 20.

[0042] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the invention, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such a combination is technically feasible.