Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
  • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
  • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
  • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
  • F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
  • F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
  • F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours

Definitions

• the present invention relates to method and system for generating power using a combined cycle, in
• Power plants such as gas turbines, produce power by combusting fuel.
• the power is usually produced in the form of electricity. This is usually referred to as the first (power) system.
• waste heat recovery system (the second (power) system) to generate additional power from the hot flue gasses produced by the first system.
• the combination of the first and second system is usually referred to as a combined cycle.
• the first system is a gas turbine operated by a Brayton cycle and the second system is a Rankine cycle, such as an organic Rankine cycle (ORC) .
• ORC organic Rankine cycle
• the flue gasses produced by a gas turbine may typically have a temperature greater than 450°C, e.g. in the range of 450°C - 650°C.
• ORC fluids comprising pentane, propane, cyclohexane, cyclopentane, butane,
• fluorohydrocarbon a ketone such as aceton or an aromatic such as toluene or thiophene .
• EP1764487 disclose the use of organic working fluids for use in an organic Rankine cycle for energy recovery, especially for utilization of heat sources having a temperature up to approx. 200°C, preferably up to approx. 180°C.
• the system includes a heat exchanger configured to be mounted inside an exhaust stack that guides hot flue gases .
• the heat exchanger is configured to receive a liquid stream of a first fluid and to generate a vapor stream of the first fluid.
• the heat exchanger is configured to include a double walled pipe, where the first fluid is disposed within an inner wall of the double walled pipe and a second fluid is disposed between the inner wall and an outer wall of the double walled pipe.
• the double walled pipe is used to shield the working fluid from direct exposure to the high temperature of the flue gasses and suggests to keep the temperature of the working fluid below 300°C.
• the second power system comprising a waste heat recovery heat exchanger
• the method further comprising:
• waste heat recovery fluid consists of fluorinated ketones
• system for generating power comprises:
• a first power system comprising a fuel burning stage arranged to burn fuel to generate primary power and a flue gas stream at a flue gas temperature greater than 450°C,
• the second power system comprising a waste heat recovery heat exchanger and a waste heat recovery fluid
• the waste heat recovery heat exchanger comprises a first fluid path arranged to receive and convey at least part of the flue gas stream, and a second fluid path arranged to receive and convey the waste heat recovery fluid
• the heat exchange wall being suitable to to be exposed to the flue gas stream at a flue gas temperature in the range of 450°C - 650°C, and the heat exchange wall being suitable to to be exposed to the waste heat recovery fluid at a temperature in the range of 350°C - 500°C,
• the working fluid comprised by the second power system consists of fluorinated ketones.
• the waste heat recovery fluid is temperature stable up to a temperature of 500°C.
• the term temperature stable is used to indicate that the molecules don't decompose under the influence of the temperature.
• the waste heat recovery fluid substantially consists of fluorinated ketones, preferably consists of
• the waste heat recovery fluid substantially consists of dodecafluoro-2-methylpentan-3- one .
• the waste heat recovery fluid comprises more than 90 mol% dodecafluoro-2-methylpentan-3-one , preferably more than 95 mol% dodecafluoro-2-methylpentan-
• the waste heat recovery fluid may be essentially pure dodecafluoro-2-methylpentan-3-one , where the skilled person will understand that the term pure is used to indicate a level of purity that is practically
• the waste heat recovery fluid essentially consisting of pure dodecafluoro-2-methylpentan-3-one may be obtained from 3M at a purity of more than 99 mol%.
• Fluorinated ketones in particular dodecafluoro-2- methylpentan-3-one , can advantageous be used as waste heat recovery fluid, for instance in a Rankine cycle, as it can be exposed to temperatures above 450°C.
• an intermediate working fluid such as an intermediate hot oil loop
• direct heat exchange between the flue gasses and the working fluid is made possible. This reduces cost and increases the efficiency of the cycle.
• fluorinated ketones in particular dodecafluoro-2-methylpentan-3-one , may also be used in an intermediate loop.
• direct heat exchange is used in this text to indicate that the exchange of heat takes place without intermediate fluid or cycles .
• direct heat exchange is not used to indicate that the fluids
• exchanging heat are mixed or brought into contact as is done in a direct heat exchanger (in which the fluids to exchange heat are mixed) .
• Heat exchange between the waste heat recovery fluid and the flue gas stream is typically done by an indirect heat exchanger in which the fluids are kept separated by a heat exchange wall through which the heat is
• a waste heat recovery fluid as defined above in particular consisting of dodecafluoro- 2-methylpentan-3-one, is stable at relatively high temperatures, i.e. in the range of 350-500°C. This avoids degradation of circulating fluids.
• waste heat exchange fluid produces power (mechanical work) in a relatively efficient way, i.e. at a 9-11% efficiency from a flue gas stream in the indicated temperature range (compared to 6 - 9% when using water) .
• the suggested waste heat recovery fluid is non-corrosive to all metals and hard polymers.
• the Global Warming Potential (GWP) of the waste heat recovery fluid is low, compared to known waste heat recovery fluids, such as chlorofluorocarbon (CFC, also known as Freon) , due to the ozone depletion potential.
• CFC chlorofluorocarbon
• Figure 1 schematically shows a system according to an embodiment
• Figure 2 schematically shows an system according to an alternative embodiment.
• a method and system in which a first and second power system are operated, wherein the second power system is powered by the heat of the flue gas stream of the first power system.
• the second power system comprises a waste heat recovery heat exchanger through which a pressurized waste heat recovery fluid is circulated, wherein the waste heat recovery fluid comprises fluorinated ketones, in
• the first power system comprises a gas turbine operated by a Brayton cycle.
• the flue gass stream produced by such a first power system typically have a temperature greater than 450°C,
• operating the second power system comprises circulating a working fluid through a heat engine cycle, in particular a Rankine cycle.
• Rankine cycles are an efficient way to transform heat into power.
• the waste heat recovery fluid may be circulated through the waste heat recovery heat exchanger as part of an intermediate heat transfer cycle. This embodiment will be described in more detail below with reference to Fig.
• the working fluid circulated through the heat engine cycle is the waste heat recovery fluid.
• the waste heat recovery heat exchanger is part of the heat engine cycle.
• the above identified waste heat recovery fluid is suitable for being cycled through a waste heat recovery heat exchanger which is exposed to a flue gas stream at a flue gas temperature greater than 450°C.
• the pressurized vaporous waste heat recovery fluid as obtained from the waste heat recovery heat exchanger has a temperature in the range of 350°C - 500°C, preferably in the range of 450°C - 500°C.
• the waste heat recovery fluid is stable up to
• the heat engine cycle comprises a condenser in which the waste heat recovery fluid is condensed against an ambient cooling stream, the ambient cooling stream being an ambient air stream or an ambient (sea) water stream.
• the working fluid may be cooled to a temperature in the range 15°C - 80°C in the condenser .
• the waste heat recovery fluid can be used in a cycle in which it experiences a temperature difference of more than 320°C, even more than 400°C or even more than 450°C. This allows cooling the waste heat recovery fluid against the ambient and heating the waste heat recovery fluid against a flue gas stream having a temperature greater than 450°C.
• operating the second power system comprises circulating the waste heat recovery fluid as working fluid through a heat engine, such as a Rankine cycle.
• the Rankine cycle comprises the following steps, which are performed simultaneously: 1) Passing the pressurized waste heat recovery fluid through the waste heat recovery heat exchanger to receive heat from the flue gas stream thereby obtaining a pressurized vaporous waste heat recovery fluid.
• the pressurized vaporous waste heat recovery fluid may have a temperature in the range of 350°C - 500°C and pressure of more than 40 bar, e.g. 50 bar.
• the expanded lower pressure vaporous waste heat recovery fluid may have a pressure of less than 3 bar, e.g. 1 bar and the temperature between 50°C - 150°C, e.g. 100°C.
• the liquid waste heat recovery fluid may have a pressure of less than 3 bar, e.g. 1 bar and a temperature between 15°C - 100°C, e.g. 50°C.
• the pressurized liquid waste heat recovery fluid may have a pressure of more than 40 bar, e.g. 50 bar and temperature in the range of 15°C - 100°C.
• Fig. 1 schematically shows a system for generating power.
• the system comprises a first power system 1 and a second power system 2.
• the first power system 1 comprises a fuel burning stage, here schematically depicted as a gas turbine.
• the gas turbine comprises a compressor 11, a fuel chamber 12 and an turbine 13.
• the turbine 13 drives the compressor 11 and excess power is used to drive shaft 14 which is coupled to a generator 15, such as an electric generator, to generate primary power.
• a flue gas stream 16 leaves the turbine 13 via an exhaust 17 at a flue gas temperature greater than 450°C.
• FIG. 1 shows a schematic view of an exemplary primary power system and that many variations are known to the skilled person.
• Fig. 1 further schematically shows a second power system 2.
• the second power system 2 is arranged to generate secondary power from the heat of the flue gas stream 16.
• the second power system 2 comprises a waste heat recovery heat exchanger 21.
• the waste heat recovery heat exchanger 21 is positioned in the exhaust 17.
• the waste heat recovery heat exchanger 17 comprises a first fluid path arranged to receive and convey at least part of the flue gas stream 16.
• the waste heat recovery heat exchanger 17 comprises a second fluid path arranged to receive and convey the waste heat recovery fluid.
• the waste heat recovery heat exchanger 17 may be any suitable type, including a plate heat exchanger.
• the waste heat recovery heat exchanger 17 is a shell and tube heat exchanger, wherein the first fluid path is at the shell side and the second fluid path is at the tube side.
• the first and second fluid paths are separated by a heat exchange wall, e.g. the walls forming the tubes of the shell and tube heat exchanger.
• Fig. 1 shows a single tube but it will be understood that more than one tube may be present, each tube wall forming a heat exchange wall.
• the heat exchange wall is a single layer wall.
• the heat exchange does not comprise internal cooling facilities, intermediate isolation layers, double walls and the like.
• the system as described here and shown in Fig. 1 comprises a working fluid in a cycle (21, 22, 23, 24, 25,
• the working fluid consisting of fluorinated ketones, in particular dodecafluoro-2-methylpentan-3-one .
• the second power system comprises a heat engine comprising waste heat recovery heat exchanger 21, (turbo-
• An outlet of the heat recovery heat exchanger 21 is in fluid communication with an inlet of expander 23 via first conduit 22; an outlet of the expander 23 is in fluid communication with an inlet of condenser 25 via second conduit 24; an outlet of the condenser 25 is in fluid communication with an inlet of pump 27 via third conduit 26; an outlet of the pump is in fluid
• the condenser 25 comprises an ambient inlet to receive an ambient cooling stream 61 and an ambient outlet to discharge a warmed ambient cooling stream 62.
• the first power system 1 generates primary power and flue gas stream 16, while the second power system 2 cycles the waste heat recovery fluid as working fluid through the above described Rankine cycle.
• the expander 23 drives drive shaft 29 which is coupled to a secondary generator 30, such as an electric generator, to generate secondary power.
• Fig. 2 schematically shows an alternative embodiment wherein the waste heat recovery fluid is not used as working fluid in a heat engine, but is used in an intermediate loop 3 to transfer heat from the waste heat recovery heat exchanger 21 to a heat engine wherein a different fluid is circulated as working fluid, such as water/steam.
• the second power system 2 comprises the heat engine and the intermediate loop 3.
• operating the second power system 2 comprises circulating the waste heat recovery fluid (consisting of fluorinated ketones, in particular consisting of dodecafluoro-2-methylpentan-3- one) through the intermediate loop 3 and circulating a working fluid through a heat engine, such as a Rankine cycle, to generate the secondary power, the heat engine comprising a heat source heat exchanger 42 and a heat sink heat exchanger 25, wherein the method comprises
• Fig. 2 shows an intermediate loop 3 in which the waste heat recovery fluid is circulated.
• the intermediate loop 3 comprises the waste heat recovery heat exchanger 21, a condenser 42 (being the heat source heat exchanger of the heat engine) and a pump 44, being connected by intermediate loop conduits 41, 43 and 45.
• An outlet of the heat recovery heat exchanger 21 is in fluid communication with an inlet of condenser 42 via first intermediate loop conduit 41; an outlet of the condenser 25 is in fluid communication with an inlet of pump 44 via second intermediate loop conduit 26; an outlet of the pump 44 is in fluid communication with an inlet of the waste heat recovery heat exchanger 21 via intermediate loop third conduit 45.
• the first power system 1 generates primary power and flue gas stream 16, while the second power system 2 cycles the waste heat recovery fluid through the above described intermediate loop 3 transferring heat from the flue gas stream 16 to the heat engine via the condenser (being the heat source heat exchanger 42) of the heat engine.
• a working fluid is circulated, driving expander 23, which drives drive shaft 29 coupled to a secondary generator 30, such as an electric generator, to generate secondary power.
• Efficiency of the second power system is computed as the ratio of net power generated to the total amount of heat available with the exhaust gas:
• W TE is the work done by turbo-expander 23
• n haust is the mass flow of the flue gas stream 16
• C P exhaust is heat capacity of flue gas stream 16
• Tambient is the ambient temperature.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Engine Equipment That Uses Special Cycles (AREA)
• Treating Waste Gases (AREA)

Priority Applications (7)

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Cited By (1)

Citations (9)

Family Cites Families (10)

• 2016
  • 2016-11-10 RU RU2018120240A patent/RU2720873C2/ru active
  • 2016-11-10 JP JP2018524358A patent/JP6868022B2/ja active Active
  • 2016-11-10 AU AU2016353483A patent/AU2016353483A1/en not_active Abandoned
  • 2016-11-10 WO PCT/EP2016/077225 patent/WO2017081131A1/en active Application Filing
  • 2016-11-10 US US15/775,196 patent/US20180340452A1/en not_active Abandoned
  • 2016-11-10 EP EP16793905.7A patent/EP3374605B1/en active Active
  • 2016-11-10 CN CN201680065552.8A patent/CN108368751B/zh not_active Expired - Fee Related
• 2019
  • 2019-11-19 AU AU2019268076A patent/AU2019268076B2/en not_active Expired - Fee Related

Patent Citations (9)

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