Steam Turbine Inlet Temperature Research Articles

Analysis of a direct vapor generation system using cascade steam-organic Rankine cycle and two-tank oil storage

A direct vapor generation solar power system using cascade steam-organic Rankine cycle and two-stage oil tanks is proposed. It offers a significantly enlarged storage capacity due to the unique discharge operation mode. Synthetic oil Therminol® VP-1 is used as the heat carrier and storage medium. Compared with the direct steam generation system, the steam turbine inlet temperature is elevated from 270 °C to 311 °C. Thermodynamic analysis indicates that the optimal equivalent heat-to-power conversion efficiency ( η e q , o p t ) is 27.91% when benzene is used as the bottom fluid and the mass of oil is 1000 tonnes. η e q , o p t is raised by 7.72–11.60% for the selected four organic fluids as compared with the direct steam generation type. The temperature drop of oil during discharge can reach about 280 °C. Economic studies demonstrate that the proposed system is more cost-effective. Its equivalent payback period is less than 5 years for a 10 MW system with 2000 tonnes of oil. Further investigation shows that it is also more advantageous than a conventional thermal oil-based indirect solar power system due to the cost reduction in heat storage. • Thermal oil is innovatively combined with a cascade steam-organic Rankine cycle. • Challenges associated with high-pressure steam generation are overcome. • An efficiency of 30.25% is obtained at a solar field temperature of 311 °C. • The temperature drop of thermal oil during discharge is significantly elevated. • The equivalent payback period is generally less than 7.5 years.

A sustainable exergy model for energy–water nexus in the hot regions: integrated combined heat, power and water desalination systems

Water scarcity is a worldwide concern for Earth citizens. Finding new methods for water concentration is essential for the extension of life. The water issue is more intense in the regions with a warm to the tropical environment. Considering the cooling demand of these regions, which consequently requires excess energy to satisfy the cooling load, having a thermal system to support three concerns of the water, cooling, and power would be the key for the warm/hot weather areas. In the present study, a novel model by integration of gas turbine power cycle with a solar parabolic collector, a steam turbine, heat recovery, steam generator, multi-effect desalination, and absorption chiller is proposed. The suggested model is optimized through developing a comprehensive multi-objective function to maximize the exergy efficiency and minimize the cost. Using the genetic algorithm method, the model is optimized based on six design parameters such as condenser pressure, number of solar parabolic through collector rows, gas turbine and steam turbine inlet temperature, high and low pressure, high- and low-pressure pinch points. The final optimal design point of this cycle enables the overall exergy efficiency of $$36.16\%$$ and $$188.43\;\$ \;{\text{h}}^{ - 1}$$ of the total cost rate value; also, this integrated energy system provides the net electrical generation of $$5.18\;{\text{MW}}$$ and the cooling load rate of $$406.18\;{\text{KW}}$$ and generates $$2.57\;{\text{kg}}\;{\text{s}}^{ - 1}$$ of desalinated water. In this novel cycle solar energy is used for preheating the inflow of the combustion chamber. A dual pressure heat recovery exploits thermal energy of flue gas, which runs both desalination and multi-effect absorption system and circulates in simultaneous water and cooling load generation. Finally, by utilizing the genetic 1 algorithm, the optimal system is developed.

Laser Multi-Pass Narrow-Gap Welding – A Promising Technology for Joining Thick-Walled Components of Future Power Plants

Today, the average worldwide efficiency of coal-fired power plants stands at about 33 percent. The consistent use of state of the art technologies would enable an increase of the average efficiency of up to 47 percent and thus a sharp reduction of greenhouse gas emissions. The importance of improvements in this field becomes apparent when reviewing e.g. plans in Europe in 2017 for new power plants to be built across the continent. About 44 percent of the envisaged 153 gigawatts are still to be generated by fossil-fuel power plants [1]. One technical solution is to increase the steam turbine inlet temperature to 700°C. This, however, requires the use of nickel-based superalloys. Only these alloys satisfy all the requirements with regard to high-temperature, corrosion and oxidation resistance and creep behavior [2], [3]. Due to their relatively poor machinability, forgeability and high material costs compared to the steel-based alloys they are to replace, a more effective welding technology is needed to overcome the disadvantages of conventional welding technologies, i.e. large quantities of filler metal required and high energy input per unit length resulting in distortion and the potential reduction of high-temperature properties.

Parametric techno-economic studies of coal/biomass co-gasification for IGCC plants with carbon capture using various coal ranks, fuel-feeding schemes, and syngas cooling methods

Summary Because of biomass's limited supply (as well as other issues involving its feeding and transportation), pure biomass plants tend to be small, which results in high production and capital costs (per unit power output) compared with much larger coal plants. Thus, it is more economically attractive to co-gasify biomass with coal. Biomass can also make an existing plant carbon-neutral or even carbon-negative if enough carbon dioxide is captured and sequestered (CCS). As a part of a series of studies examining the thermal and economic impact of different design implementations for an integrated gasification combined cycle (IGCC) plant fed with blended coal and biomass, this paper focuses on investigating various parameters, including radiant cooling versus syngas quenching, dry-fed versus slurry-fed gasification (particularly in relation to sour-shift and sweet-shift carbon capture systems), oxygen-blown versus air-blown gasifiers, low-rank coals versus high-rank coals, and options for using syngas or alternative fuels in the duct burner for the heat recovery steam generator (HRSG) to achieve the desired steam turbine inlet temperature. Using the commercial software, Thermoflow®, the case studies were performed on a simulated 250-MW coal IGCC plant located near New Orleans, Louisiana, and the coal was co-fed with biomass using ratios ranging from 10% to 30% by weight. Using 2011 dollars as a basis for economic analysis, the results show that syngas coolers are more efficient than quench systems (by 5.5 percentage points), but are also more expensive (by $500/kW and 0.6 cents/kW h). For the feeding system, dry-fed is more efficient than slurry-fed (by 2.2–2.5 points) and less expensive (by $200/kW and 0.5 cents/kW h). Sour-shift CCS is both more efficient (by 3 percentage points) and cheaper (by $600/kW or 1.5 cents/kW h) than sweet-shift CCS. Higher-ranked coals are more efficient than lower-ranked coals (2.8 points without biomass, or 1.5 points with biomass) and have lower capital cost (by $600/kW without using biomass, or $400/kW with biomass). Finally, plants with biomass and low-rank coal feedstock are both more efficient and have lower costs than those with pure coal: just 10% biomass seems to increase the efficiency by 0.7 points and reduce costs by $400/kW and 0.3 cents/kW h. However, for high-rank coals, this trend is different: the efficiency decreases by 0.7 points, and the cost of electricity increases by 0.1 cents/kW h, but capital costs still decrease by about $160/kW. Copyright © 2016 John Wiley & Sons, Ltd.

Estimation of operating parameters of a reheat regenerative power cycle using simplex search and differential evolution based inverse methods

Abstract In this study, simplex search method (SSM) and a differential evolution (DE) based inverse algorithm are applied to estimate fuel flow rate (FFR), boiler pressure (BP) and steam turbine (ST) inlet temperature (STIT) of a ST based power cycle. First a theoretical model simulates the cycle performance in terms of net power, efficiency (energy and exergy) and total irreversibility at various FFRs, BPs and STITs. The forward model based results show that the net power increases linearly with FFR while also producing more irreversible losses at higher FFR. The cycle performance also improves at higher BP and STIT. The inverse analysis shows that the DE based method is more appropriate than the SSM where the searching range of parameters is specified and parameter estimation is done from the range of specified parameter values. In SSM, the estimation depends upon the chosen initial guess values and convergence criterion sometimes is not fulfilled with some guessed values of the parameters. Both the inverse methods, however give multiple combinations of parameters and thus provides sufficient scope at the hands of the designer to select the appropriate combinations of parameters required for meeting a particular power requirement.

Energy and exergy based performance analyses of a solid oxide fuel cell integrated combined cycle power plant

Abstract This article provides the energy and exergy based performance analysis of a solid oxide fuel cell (SOFC) – gas turbine (GT) – steam turbine (ST) combined cycle power plant. The system utilizes the GT exhaust heat for fuel and air preheating subsequently in a fuel recuperator (FR) and an air recuperator (AR) before finally producing steam in a heat recovery steam generator (HRSG) coupled with the ST cycle. It considers 30% external reforming in a pre-reformer (PR) by steam extracted from the bottoming ST plant. The study considers the effect of additional fuel burning in the combustion chamber (CC) as a means for increasing the net GT and ST power output. A detailed parametric analysis based on variation of compressor pressure ratio (CPR), fuel flow rate (FFR), air flow rate (AFR), current density, single level boiler pressure and ST inlet temperature (STIT) is also provided. Results indicate improved system performance at higher CPR. The optimum single level boiler pressure is found to be 40 bar with 50% additional fuel burning. Burning of additional fuel improves the GT and ST power output, however with reduction in the plant’s overall efficiency. Further comparison of performance with a similar other system where the AR is placed head of the FR indicates slightly better performance of the proposed system with FR ahead of AR (FRAOAR).

Modelling and exergoeconomic based design optimisation of combined power plants

In this research a Combined Cycle Power Plant (CCPP) which can provide 80 MW of electrical power has been studied. The design parameters of the plant were chosen as: compressor pressure ratio, compressor isentropic efficiency, gas turbine isentropic efficiency, and turbine inlet temperature, pinch difference temperature, steam turbine inlet temperature, steam turbine isentropic efficiency, condenser pressure, and pump isentropic efficiency. In order to optimally find the design parameters a thermoeconomic approach has been followed. An objective function representing the total cost of the plant in terms of dollar per second was defined as the sum of the operating cost related to the fuel consumption, and the capital investment for equipment purchase and maintenance costs. Finally, the optimal values of decision variables were obtained by minimising the objective function using Sequential Quadratic Programming (SQP) for, 50, 60, 70, and 80 MW of net power output.

AN EXERGY COST ANALYSIS OF A COGENERATION PLANT

The exergy analysis, including the calculation of the unit exergetic cost of all flows of the cogeneration plant, was the main purpose of the thermoeconomic analysis of the STAG (STeam And Gas) combined cycle CHP (Combined Heat and Power) plant. The combined cycle cogeneration plant is composed of a GE10 gas turbine (11250 kW) coupled with a HRSG (Heat Recovery Steam Generator) and a condensing extraction steam turbine. The GateCycleTM Software was used for the modeling and simulation of the combined cycle CHP plant thermal scheme, and calculation of the thermodynamic properties of each flow (Mass Flow, Pressure, Temperature, Enthalpy). The entropy values for water and steam were obtained from the Steam Tab software while the entropy and exergy of the exhaust gases were calculated as instructed by. For the calculation of the unit exergetic cost was used the neguentropy and Structural Theory of Thermoeconomic. The GateCycleTM calculations results were exported to an Excel sheet to carry out the exergy analysis and the unit exergetic cost calculations with the thermoeconomic model that was created for matrix inversion solution. Several simulations were performed varying separately five important parameters: the Steam turbine exhaust pressure, the evaporator pinch point temperature, the steam turbine inlet temperature, Rankine cycle operating pressure and the stack gas temperature to determine their impact in the recovery cycle heat exchangers transfer area, power generation and unit exergetic cost.

5143 Resource-based data availability for erbB2-driven breast cancer in Asian women: experts' opinion

In this study, simplex search method (SSM) and a differential evolution (DE) based inverse algorithm are applied to estimate fuel flow rate (FFR), boiler pressure (BP) and steam turbine (ST) inlet temperature (STIT) of a ST based power cycle. First a theoretical model simulates the cycle performance in terms of net power, efficiency (energy and exergy) and total irreversibility at various FFRs, BPs and STITs. The forward model based results show that the net power increases linearly with FFR while also producing more irreversible losses at higher FFR. The cycle performance also improves at higher BP and STIT. The inverse analysis shows that the DE based method is more appropriate than the SSM where the searching range of parameters is specified and parameter estimation is done from the range of specified parameter values. In SSM, the estimation depends upon the chosen initial guess values and convergence criterion sometimes is not fulfilled with some guessed values of the parameters. Both the inverse methods, however give multiple combinations of parameters and thus provides sufficient scope at the hands of the designer to select the appropriate combinations of parameters required for meeting a particular power requirement.

Cooling performance of grid-sheets for highly loaded ultra-supercritical steam turbines

In order to increase efficiency and achieve a further CO2-reduction, the next generation of power plant turbines will have steam turbine inlet temperatures that are considerably higher than the current ones. The high pressure steam turbine inlet temperature is expected to be increased up to approximately 700°C with a live steam pressure of 30 MPa. The elevated steam parameters in the high and intermediate pressure turbines can be encountered with Ni-base alloys, but this is a costly alternative associated with many manufacturing difficulties. Collaborative research centre 561 “Thermally Highly Loaded, Porous and Cooled Multi-Layer Systems for Combined Cycle Power Plants” at RWTH Aachen University proposes cooling the highly loaded turbines instead, as this would necessitate the application of far less Ni-base alloys.

Modeling, numerical optimization, and irreversibility reduction of a triple-pressure reheat combined cycle

The main methods for improving the efficiency of the combined cycle are: increasing the inlet temperature of the gas turbine (TIT), reducing the irreversibility of the heat recovery steam generator (HRSG), and optimization. In this paper, modeling and optimization of the triple-pressure reheat combined cycle as well as irreversibility reduction of its HRSG are considered. Constraints were set on the minimum temperature difference for pinch points ( PP m ), the temperature difference for superheat approach, the steam turbine inlet temperature and pressure, the stack temperature, and the dryness fraction at steam turbine outlet. The triple-pressure reheat combined cycle was optimized at 41 different maximum values of TIT using two different methods; the direct search and the variable metric. A feasible technique to reduce the irreversibility of the HRSG of the combined cycle was introduced. The optimized and the reduced-irreversibility triple-pressure reheat combined cycles were compared with the regularly designed triple-pressure reheat combined cycle, which is the typical design for a commercial combined cycle. The effects of varying the TIT on the performance of all cycles were presented and discussed. The results indicate that the optimized triple-pressure reheat combined cycle is up to 1.7% higher in efficiency than the reduced-irreversibility triple-pressure reheat combined cycle, which is 1.9–2.1% higher in efficiency than the regularly designed triple-pressure reheat combined cycle when all cycles are compared at the same values of TIT and PP m . The optimized and reduced-irreversibility combined cycles were compared with the most efficient commercially available combined cycle at the same value of TIT.

Influence of Different Forming and Heat Treatment Stages on the Properties of P92-Sheet

To improve the efficiency factor of combined cycle power plants from the state-of-the-art 58% towards 65% in 2025, the steam turbine inlet temperature is to be increased up to approximately 700 °C at a steam inlet pressure of 300 bar. Modern ferritic steels like P92 however do not withstand such harsh operating conditions, necessitating the need for a cooling system. With the help of sheet, a sandwich material consisting of two face sheets and a core of woven wire mesh, the cooling is to be accomplished in the steam turbine. Since P92-sheet needed for the face sheets of the grid sheet is not available in industry, the sheet was produced on laboratory scale. However, the used production process yielded partial inhomogeneous material properties, clarifying the need for the redevelopment of the former production process. In the new production process the cast round block was sawn to slices, which enabled a reduction of the number of required heatings above the austinitisation temperature. Using this new production process more homogeneous material properties were expected, which is evaluated using thickness measurements, chemical analyses among others. Furthermore, the effect of each process stage on the mechanical properties and microstructure were analysed.

Modeling, numerical optimization, and irreversibility reduction of a dual-pressure reheat combined-cycle

Abstract Optimizing the gas-turbine combined-cycle is an important method for improving its efficiency. In this paper, a dual-pressure reheat combined-cycle was modeled and optimized for 80 cases. Constraints were set on the minimum temperature-difference for pinch points (PPm), superheat approach temperature-difference, steam-turbine inlet temperature and pressure, stack temperature, and dryness fraction at the steam-turbine’s outlet. The dual-pressure reheat combined-cycle was optimized using two different methods; the direct search and the variable metric. A technique to reduce the irreversibility of the steam generator of the combined cycle was introduced. The optimized and the reduced-irreversibility dual-pressure reheat combined-cycles were compared with the regularly-designed dual-pressure reheat combined-cycle, which is the typical design for a commercial combined-cycle. The effects of varying the inlet temperature of the gas turbine (TIT) and PPm on the performance of all cycles were presented and discussed. The results indicated that the optimized combined-cycle is up to 1% higher in efficiency than the reduced-irreversibility combined-cycle, which is 2–2.5% higher in efficiency than the regularly-designed combined-cycle when compared for the same values of TIT and PPm. The advantages of the optimized and reduced-irreversibility combined-cycles were manifested when compared with the most efficient commercially-available combined cycle at the same value of TIT.

Modelling and numerical optimization of dual- and triple-pressure combined cycles

Optimization of the combined-cycle efficiency by optimizing the gas or steam cycle efficiencies does not guarantee an optimum combined cycle. In this paper, triple-pressure and dual-pressure non-reheat combined cycles are modelled and optimized for 50 and 300 cases respectively. The layout for the triple-pressure cycle was chosen to reduce NOX emission. Constraints are set on the pressure of the feed water heater, the minimum temperature difference for pinch points, the superheat approach temperature difference, the steam turbine inlet temperature and the dryness fraction at the steam turbine outlet. The combined-cycle efficiency is optimized using two different methods: the direct search method and the variable metric method. The effects of the inlet temperature of both the gas turbine and the steam turbine and of the minimum pinch point temperature difference on the performance of the optimum cycles are presented and discussed. The optimization results indicate that the layout for the triple-pressure cycle redefines the temperature differences for pinch points and adds a constraint on the intermediate pressure of the steam generator, which reduces the optimum efficiency by 2–3 percent when compared with the dual-pressure cycle under the same conditions. For the dual-pressure cycle, the optima of the most efficient cases were found to be 0.5-2 percent higher in efficiency than the optima of the regular design case, which is the usual design case for a commercial combined cycle. The optimum dual-pressure combined cycle was found to be almost as efficient as the most efficient commercially available triple-pressure reheat combined cycle, when compared at the same firing temperature.

97/04939 A review of NO x reduction on zeolitic catalysts under diesel exhaust conditions : Gilot, P. et al. Fuel, 1997, 76, (6), 507–515

Optimizing the gas-turbine combined-cycle is an important method for improving its efficiency. In this paper, a dual-pressure reheat combined-cycle was modeled and optimized for 80 cases. Constraints were set on the minimum temperature-difference for pinch points (PPm), superheat approach temperature-difference, steam-turbine inlet temperature and pressure, stack temperature, and dryness fraction at the steam-turbine’s outlet. The dual-pressure reheat combined-cycle was optimized using two different methods; the direct search and the variable metric. A technique to reduce the irreversibility of the steam generator of the combined cycle was introduced. The optimized and the reduced-irreversibility dual-pressure reheat combined-cycles were compared with the regularly-designed dual-pressure reheat combined-cycle, which is the typical design for a commercial combined-cycle. The effects of varying the inlet temperature of the gas turbine (TIT) and PPm on the performance of all cycles were presented and discussed. The results indicated that the optimized combined-cycle is up to 1% higher in efficiency than the reduced-irreversibility combined-cycle, which is 2–2.5% higher in efficiency than the regularly-designed combined-cycle when compared for the same values of TIT and PPm. The advantages of the optimized and reduced-irreversibility combined-cycles were manifested when compared with the most efficient commercially-available combined cycle at the same value of TIT.