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J H Horlock - One of the best experts on this subject based on the ideXlab platform.
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Simplified analyses of some vapour power cycles
2016Co-Authors: J H HorlockAbstract:A range of vapour power cycles is analysed, using the assumption originally made by Schaff that along a turbine expansion line the diffoence between the (local) enthalpy (h) and the liquid enthalpy at the same pressure (hL) may remain unchanged (fl = h- h, is constant). The thermodynamics of the assumption are critically examined and it is found to be valid only over strictly limited ranges of properties (usually low-pressure levels). However, if such limitations are accepted, the analyses provide understanding of the effects of various key parameters on thermal eflciency, and of measures (such as Feed Heating, reheat, dual pressure boilers, etc.) that are taken to raise that eflciency. Key words: vapour power cycles, thermodynamics, thermal efficiency, Schaffs assumption, steam turbine NOTATION S sup p 1 i e d t turbine (isentropic efficiency) TR true Lower case letters are used for specific properties. specific heat at constant pressure enthalpy the irreversibility mass fraction (bled steam) pressure areas on the T-s diagram heat quantity gas constant entropy temperature work output increases in enthalpy of Feed water (defined in text) Schaffs constant = h- h, thermal (cycle) efficiency mass flow ratio (high pressure to low pressure) defined in equation (43) as Afl/fls = (BR- B S Y P S defined in equation (13) as (4- W ( h 3- h2) 1, 2, 3, 4, 5, 6, states in gas cycl
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Simplified analyses of some vapour power cycles
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 1996Co-Authors: J H HorlockAbstract:A range of vapour power cycles is analysed, using the assumption originally made by Schaff that along a turbine expansion line the difference between the (local) enthalpy (h) and the liquid enthalpy at the same pressure (hL) may remain unchanged (β = h – hLis constant). The thermodynamics of the assumption are critically examined and it is found to be valid only over strictly limited ranges of properties (usually low-pressure levels). However, if such limitations are accepted, the analyses provide understanding of the effects of various key parameters on thermal efficiency, and of measures (such as Feed Heating, reheat, dual pressure boilers, etc.) that are taken to raise that efficiency.
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The Use of Feed Heating in the Steam Cycle of a Combined Cycle Power Plant
Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 1991Co-Authors: J H HorlockAbstract:A simplified analysis is given for determination of the overall efficiency of a recuperative combined gas turbine/steam power plant, with and without Feed Heating. It is shown that for prescribed state properties in the (higher) gas turbine plant and specified pressures in the (lower) steam cycle, Feed Heating leads to reduced plant overall efficiency. However, if the temperature of the gas leaving the heat-recovery steam generator is limited (to avoid corrosion in the heat-recovery steam generator) then the disadvantage resulting from the introduction of Feed Heating is small.
Dominika Janowczyk - One of the best experts on this subject based on the ideXlab platform.
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Heat integration analysis and optimization for a post combustion CO2 capture retrofit study of SaskPower’s Shand Power Station
International Journal of Greenhouse Gas Control, 2019Co-Authors: Stavroula Giannaris, Brent Jacobs, Wayuta Srisang, Corwyn Bruce, Dominika JanowczykAbstract:Abstract Post-combustion CO2 capture processes require thermal energy (from steam) for amine regeneration. In coal-fired power stations, steam can be extracted from within the steam cycle – resulting in a power production penalty. Heat integration is the study of minimizing energy consumption while maximizing heat recovery; required for successful CCS retrofits. In October 2014, the world’s first fully integrated carbon capture facility, SaskPower’s Boundary Dam Unit 3 (BD3), went on line. Various modifications to the turbine and Feed Heating system at BD3 contributed greatly to overall project costs. Novel heat integration strategies can reduce these costs. SaskPower’s Shand Power Station (Shand) is a 305 MW, single unit, subcritical, lignite coal-fired power plant producing approximately 1100 kg of CO2/MWh. Shand’s capacity is twice that of BD3’s - an ideal candidate for a CCS scale-up project. Using the design of the BD3 facility as a basis, heat integration analysis of the existing steam cycle at Shand was conducted using GateCycle™with aims to minimize costly modifications to the Feed Heating system. A baseline model was built using Shand’s heat balance and served as the design case. Configurations of steam extractions to the deaerator (DEA), extractions to the reboiler, and utilization of a flue gas cooler (FGC) working in conjunction with a condensate pre-heater (CPH) train were investigated. Optimization of steam extraction to the reboiler and a novel configuration of the condensate preHeating train integrated within the LP Feed Heating system were also accomplished.
Lourdes Garciarodriguez - One of the best experts on this subject based on the ideXlab platform.
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preliminary assessment of solar organic rankine cycles for driving a desalination system
Desalination, 2007Co-Authors: Agusti M Delgadotorres, Lourdes GarciarodriguezAbstract:Abstract A detailed analysis of low power (100 kW) solar-driven Rankine cycles in the medium temperature range has been carried out. Toluene, octamethylcyclotetrasiloxane (D4) and hexamethyldisiloxane (MM) has been considered as working fluids of organic Rankine cycle (ORC). Direct solar vapor generation configuration of solar ORC has been analysed and characterized with LS3 and IND300 parabolic trough collector (PTC) models. The analysis has been carried out for condensation temperatures in the ORC between 35oC and 115oC so that thermal power rejected can be used in different ways related to desalination processes (preHeating of reverse osmosis Feed, Heating of Feed of conventional or membrane distillation processes). The results obtained indicate a great importance of the regeneration process and such that is greater in the case of D4 and MM than toluene. On the other hand, vapor superHeating implies an ORC thermal efficiency grown only if is accomplished by regeneration process with minimum certain values of recuperator effectiveness. From global efficiency point of view, in a 100 kW gross mechanical output solar ORC with identical condensation temperatures toluene presents the best behaviour follows by D4 and MM. The difference between toluene and D4 and MM is particularly important if the regeneration process is not considered. In a system with LS3 PTC an a recuperator´s effectiveness of 0.8, global efficiency values up to 22.3%, 19.3% and 18.3% with toluene, D4 and MM as working fluids can be reached respectively if condensation temperature is set to 35oC. These values came down to 15.3%, 12.8% and 11% respectively if condensation temperature is set to 115oC. If solar system is consisting of IND300 PTC global efficiency values are smaller than previously mentioned. In that case, global efficiency values up to 17.3%, 15.7% and 15% with toluene, D4 and MM as working fluids can be reached respectively if condensation temperature is set to 35oC. With a condensation temperature of 115oC the values are 11%, 10% and 8.8%.
Zoe Bignell - One of the best experts on this subject based on the ideXlab platform.
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Aerodynamic Analysis of Steam Turbine Feed-Heating Steam Extractions
Journal of Engineering for Gas Turbines and Power, 2014Co-Authors: Budimir Rosic, C. M. Mazzoni, Zoe BignellAbstract:Feed-Heating in steam turbines, the use of steam extracted from the turbine to heat the Feed-water, is known to raise the plant efficiency and so is included in most steam turbine power plant designs. The steam is extracted through an extraction slot that runs around the casing downstream of a rotor blade row. The slot is connected to a plenum, which runs around the outside of the turbine annulus. Steam flows to the Feed-heaters through a pipe connected usually to the bottom of the plenum. The steam extraction is driven by a circumferentially nonuniform pressure gradient in the plenum. This causes the mass flow rate of steam extracted to vary circumferentially, which affects the main passage flow downstream of the extraction point. The flow in the extraction plenum and the influence of the steam extraction on the mainstream aerodynamics is analyzed numerically in this paper. A complete annulus with the extraction slot and plenum together with the downstream stator and rotor blade rows is modeled in this study. The results reveal a highly nonuniform steam extraction around the annulus with the highest extraction rates from the bottom nearest the extraction pipe and the lowest at the top of the annulus. This difference in extraction rates modifies the flow angle and loss circumferential distribution downstream of the stator blade row. This study finds out that the distribution of steam extraction around the annulus and its influence on the main passage flow could be greatly improved by changing the shape and increasing the volume of the extraction slot and plenum.
Stavroula Giannaris - One of the best experts on this subject based on the ideXlab platform.
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Heat integration analysis and optimization for a post combustion CO2 capture retrofit study of SaskPower’s Shand Power Station
International Journal of Greenhouse Gas Control, 2019Co-Authors: Stavroula Giannaris, Brent Jacobs, Wayuta Srisang, Corwyn Bruce, Dominika JanowczykAbstract:Abstract Post-combustion CO2 capture processes require thermal energy (from steam) for amine regeneration. In coal-fired power stations, steam can be extracted from within the steam cycle – resulting in a power production penalty. Heat integration is the study of minimizing energy consumption while maximizing heat recovery; required for successful CCS retrofits. In October 2014, the world’s first fully integrated carbon capture facility, SaskPower’s Boundary Dam Unit 3 (BD3), went on line. Various modifications to the turbine and Feed Heating system at BD3 contributed greatly to overall project costs. Novel heat integration strategies can reduce these costs. SaskPower’s Shand Power Station (Shand) is a 305 MW, single unit, subcritical, lignite coal-fired power plant producing approximately 1100 kg of CO2/MWh. Shand’s capacity is twice that of BD3’s - an ideal candidate for a CCS scale-up project. Using the design of the BD3 facility as a basis, heat integration analysis of the existing steam cycle at Shand was conducted using GateCycle™with aims to minimize costly modifications to the Feed Heating system. A baseline model was built using Shand’s heat balance and served as the design case. Configurations of steam extractions to the deaerator (DEA), extractions to the reboiler, and utilization of a flue gas cooler (FGC) working in conjunction with a condensate pre-heater (CPH) train were investigated. Optimization of steam extraction to the reboiler and a novel configuration of the condensate preHeating train integrated within the LP Feed Heating system were also accomplished.