A Supercritical CO2 Brayton Cycle Micro Turbine for Waste Heat Conversion: Optimization Layout in Cogenerative Applications

2021 ◽  
Author(s):  
Fabrizio Reale ◽  
Raniero Sannino ◽  
Raffaele Tuccillo
Keyword(s):  
Gas Turbines ◽  
Supercritical Co2 ◽  
Waste Heat ◽  
Mechanical Energy ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Thermal Source ◽  
Brayton Cycle ◽  
Micro Turbine

Abstract Waste heat recovery (WHR) can represent a good solution to increase overall performance of energy systems, even more in case of small systems. The exhaust gas at the outlet of micro gas turbines (MGTs) has still a large amount of thermal energy that can be converted into mechanical energy, because of its satisfactory temperature levels, even though the typical MGT layouts perform a recuperated cycle. In recent studies, supercritical CO2 Brayton Cycle (sCO2 GT) turbines were studied as WHR systems whose thermal source was the exhausts from gas turbines. In particular, subject of this study is the 100 kW MGT Turbec T100. In this paper, the authors analyze innovative layouts, with comparison in terms of performance variations and cogenerative indices. The study was carried out through the adoption of a commercial software, Thermoflex, for the thermodynamic analysis of the layouts. The MGT model was validated in previous papers while the characteristic parameters of the bottoming sCO2 GT were taken from the literature. The combined cycle layouts include simple and recompression sCO2 bottoming cycles and different fuel energy sources like conventional natural gas and syngases derived by biomasses gasification. A further option of bottoming cycle was also considered, namely an organic Rankine cycle (ORC) system for the final conversion of waste heat from sCO2 cycle into additional mechanical energy. Finally, the proposed plants have been compared, and the improvement in terms of flexibility and operating range have been highlighted.

Numerical Study of a Micro Gas Turbine Integrated With a Supercritical CO2 Brayton Cycle Turbine

2018 ◽  
Author(s):  
Fabrizio Reale ◽  
Vincenzo Iannotta ◽  
Raffaele Tuccillo
Keyword(s):  
Gas Turbines ◽  
Waste Heat ◽  
Numerical Study ◽  
Organic Rankine Cycle ◽  
Energy Systems ◽  
Rankine Cycle ◽  
Energy System ◽  
Small Scale ◽  
Brayton Cycle ◽  
Integrated Energy System

The primary need of reducing pollutant and greenhouse gas emissions has led to new energy scenarios. The interest of research community is mainly focused on the development of energy systems based on renewable resources and energy storage systems and smart energy grids. In the latter case small scale energy systems can become of interest as nodes of distributed energy systems. In this context micro gas turbines (MGT) can play a key role thanks to their flexibility and a strategy to increase their overall efficiency is to integrate gas turbines with a bottoming cycle. In this paper the authors analyze the possibility to integrate a MGT with a super critical CO2 Brayton cycle turbine (sCO2 GT) as a bottoming cycle (BC). A 0D thermodynamic analysis is used to highlight opportunities and critical aspects also by a comparison with another integrated energy system in which the waste heat recovery (WHR) is obtained by the adoption of an organic Rankine cycle (ORC). While ORC is widely used in case of middle and low temperature of the heat source, s-CO2 BC is a new method in this field of application. One of the aim of the analysis is to verify if this choice can be comparable with ORC for this operative range, with a medium-low value of exhaust gases and very small power values. The studied MGT is a Turbec T100P.

Thermodynamic Optimization and Off-Design Performance Analysis of a Toluene Based Rankine Cycle for Waste Heat Recovery From Medium-Sized Gas Turbines

2012 ◽  
Author(s):  
Carlo Carcasci ◽  
Riccardo Ferraro
Keyword(s):  
Gas Turbines ◽  
Waste Heat ◽  
Water Cycle ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Industrial Applications ◽  
Working Fluid ◽  
Main Process ◽  
Thermal Source ◽  
Medium Temperature

In the last years, the accelerated consumption of fossil fuels has caused many serious environmental problems such as global warming, the depletion of the ozone layer and atmospheric pollution. Similarly, low-temperature waste heat which is discharged in several industrial processes, contributes to thermal pollution and damages the environment. Furthermore, many industrial applications use low enthalpy thermal sources, where the conventional systems for the conversion of thermal energy into electrical energy, based on a Rankine water cycle, work with difficulty. Thus, the Organic Rankine Cycle can be considered a promising process for the conversion of heat at low and medium temperature whenever the conventional water cycle causes problems. Using an organic working fluid instead of water, the ORC system works like the bottom cycle of a conventional steam power plant. This kind of cycle allows a high utilization of the available thermal source. Moreover, the choice of the working fluid is critical, because it should meet several environment standards and not only certain thermophysical properties. This paper illustrates the results for the simulations of an Organic Rankine Cycle based on a gas turbine with a diathermic oil circuit. The selected working fluid is toluene. The design is performed with a sensitivity analysis of the main process parameters, the organic Rankine cycle is optimized by varying the main pressure of the fluid at different temperatures of the oil circuit. The off-design is performed by varying the temperature of the air condenser.

Waste Heat Recovery From Closed Brayton Cycle Using Organic Rankine Cycle: Thermodynamic Analysis

2009 ◽  
Author(s):  
Mortaza Yari
Keyword(s):  
Waste Heat ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Exergy Destruction ◽  
Evaporator Temperature ◽  
Destruction Rate

This study examines the performance of a gas-cooled nuclear power plant with closed Brayton cycle (CBC) combined with an organic Rankine cycle (ORC) plant, as well as the irreversibility within the system. Individual models have been developed for each component, through applications of the first and second laws of thermodynamics. The overall system performance is then analyzed by employing individual models and further application of thermodynamic laws for the entire cycle, to evaluate the thermal efficiency and entropy production of the plant. The effects of the turbine inlet temperature, compressor pressure ratio, evaporator temperature, and temperature difference in the evaporator on the combined cycle first-law, second-law efficiency and exergy destruction rate are studied. Finally optimization of the combined cycle in a systematic way has been developed and discussed. It was found that the combined cycle first-law efficiency is about 9.5–10.1% higher than the simple CBC cycle. Also, the exergy destruction rate for the GT-MHR/ORC combined cycle, is about 6.5–8.3% lower than that of the GT-MHR cycle.

scholarly journals A Software Tool for Automatic Geometry Generation of a Micro Turbine

2020 ◽  
Vol 22 (2) ◽  
pp. 465-478
Author(s):  
Simon P. Hoffmann ◽  
Frank U. Rückert ◽  
Danjana Theis ◽  
Alexander G. Ruffino ◽  
Daniel Lehser-Pfeffermann ◽  
...  
Keyword(s):  
Power Plants ◽  
Waste Heat ◽  
Mechanical Energy ◽  
Organic Rankine Cycle ◽  
Software Tool ◽  
Electrical Energy ◽  
Rankine Cycle ◽  
Combustion Engines ◽  
Solar Power Plants ◽  
Micro Turbine

AbstractHeat recovery plays an important role in increasing the efficiency of renewable energy facilities like biomass furnaces, solar power plants or biofuel combustion engines. As the overall efficiency of the facilities can be increased by recovering the energy. The available waste heat can be converted directly into mechanical energy, pressure or subsequently converted into electrical energy by coupling the expansions machine with a generator. The waste heat can be converted by Organic Rankine Cycle (ORC). Therefore, an expansion machine, e.g. a turbine is required. Also small amounts of waste heat can be recovered, if so-called micro turbines are used. Design and construction of such micro turbines always follow fixed rules. Aim of this work is to explain the rules how to design a micro turbine. Furthermore, our workflow and a software tool which follows these rules should be presented.

Biomass combined cycles based on externally fired gas turbines and organic Rankine expanders

2011 ◽  
Vol 225 (8) ◽  
pp. 1066-1075 ◽  
Author(s):  
C M Invernizzi ◽  
P Iora ◽  
R Sandrini
Keyword(s):  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Inlet Temperature ◽  
System A ◽  
Combined Cycles

This article investigates the possibility to enhance the performance of a biomass organic Rankine cycle (ORC) plant by adding an externally fired gas turbine (EFGT), yielding a combined EFGT + ORC system. A typical ORC configuration is first modelled and validated on data available from an existing unit 1.5 MW reference plant. Then, different working fluids belonging to the methyl-substituted benzene series and linear methylpolysiloxanes have been evaluated for the ORC section on the basis of both thermodynamics considerations and design issues of the regenerator and the turbine. Results of the simulations of the combined cycle (CC) referred to a furnace size of about unit 9 MW, assuming a maximum GT inlet temperature of 800 °C, show a maximum efficiency of 23 per cent, obtained in the case where toluene is adopted as a working fluid for the bottoming section. This value is about 4 points per cent higher than the efficiency of the corresponding simple ORC. Finally, to conclude, some preliminary considerations are given regarding the techno-economic feasibility of the combined configuration, suggesting the need of a further investigation on the possible technological solution for the furnace which represents the main uncertainty in the resulting costs of the CC.

Thermoeconomic Analysis of a Combined Natural Gas Cogeneration System With a Supercritical CO2 Brayton Cycle and an Organic Rankine Cycle

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Zhen Pan ◽  
Mingyue Yan ◽  
Liyan Shang ◽  
Ping Li ◽  
Li Zhang ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Inlet Temperature ◽  
Total System ◽  
Brayton Cycle ◽  
Exhaust Gas ◽  
Total Cost ◽  
Cogeneration System ◽  
Isentropic Efficiency

Abstract This paper proposes a new type of Gas Turbine Cycle-supercritical CO2 Brayton/organic Rankine cycle (GT-SCO2/ORC) cogeneration system, in which the exhaust gas from gas-fired plants generates electricity through GT and then the remaining heat is absorbed by the supercritical CO2 (SCO2) Brayton cycle and ORC. CO2 contained in the exhaust gas is absorbed by monoethanolamine (MEA) and liquefied via liquified natural gas (LNG). Introducing thermodynamic efficiencies, thermoeconomic analysis to evaluate the system performance and total system cost is used as the evaluation parameter. The results show that the energy efficiency and exergy efficiency of the system are 56.47% and 45.46%, respectively, and the total cost of the product is 2798.38 $/h. Moreover, with the increase in air compressor (AC) or gas turbine isentropic efficiency, GT inlet temperature, and air preheater (AP) outlet temperature, the thermodynamic efficiencies have upward trends, which proves these four parameters optimize the thermodynamic performance. The total system cost can reach a minimum value with the increase in AC pressure ratio, GT isentropic efficiency, and AC isentropic efficiency, indicating that these three parameters can optimize the economic performance of the cycle. The hot water income increases significantly with the increase in the GT inlet temperature, but it is not cost-effective in terms of the total cost.

Efficiency Improvement of Natural Gas Combined Cycle Power Plant With CO2 Capturing and Sequestration

2012 ◽  
Author(s):  
Abdullah Al-Abdulkarem ◽  
Yunho Hwang ◽  
Reinhard Radermacher
Keyword(s):  
Natural Gas ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Simulation Software ◽  
Combined Cycle ◽  
Co2 Removal ◽  
Efficiency Improvement ◽  
Absorption Chillers ◽  
Natural Gas Combined Cycle

Although natural gas is considered as a clean fuel compared to coal, natural gas combined cycles (NGCC) emit high amounts of CO2 at the plant site. To mitigate global warming caused by the increase in atmospheric CO2, CO2 capture and sequestration (CCS) using amine absorption is proposed. However, implementing this CCS system increases the energy consumption by about 15–20%. Innovative processes integration and waste heat utilization can be used to improve the energy efficiency. Four waste heat sources and five potential uses were uncovered and compared using a parameter defined as the ratio of power gain to waste heat. A new integrated CCS configuration is proposed, which integrates the NGCC with the CO2 removal and CO2 compression cycles. HYSYS simulation software was used to simulate the CO2 removal cycle using monoethanolamine (MEA) solution, NGCC, CO2 compression cycle, CO2 liquefaction cycles and Organic Rankine Cycle (ORC). The developed models were validated against experimental data from the literature with good agreements. Two NGCC with steam extraction configurations were optimized using Matlab GA tool coupled with HYSYS simulation software. Efficiency improvement in one of the proposed CCS configurations that uses the available waste heat in absorption chillers to cool the inlet-air to the gas turbine and to run an ORC, and uses the developed CO2 liquefaction and pumping instead of multistage compression is 6.04 percent point, which represents 25.91 MW more power than the conventional CCS configuration.

scholarly journals Technologies for Waste Heat Recovery in Off-Shore Applications

2013 ◽  
Author(s):  
Leonardo Pierobon ◽  
Fredrik Haglind ◽  
Rambabu Kandepu ◽  
Alessandro Fermi ◽  
Nicola Rossetti
Keyword(s):  
Thermal Efficiency ◽  
Heat Recovery ◽  
Net Present Value ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Present Value ◽  
Payback Time ◽  
Low Weight

In off-shore oil and gas platforms the selection of the gas turbine to support the electrical and mechanical demand on site is often a compromise between reliability, efficiency, compactness, low weight and fuel flexibility. Therefore, recovering the waste heat in off-shore platforms presents both technological and economic challenges that need to be overcome. However, onshore established technologies such as the steam Rankine cycle, the air bottoming cycle and the organic Rankine cycle can be tailored to recover the exhaust heat off-shore. In the present paper, benefits and challenges of these three different technologies are presented, considering the Draugen platform in the North Sea as a base case. The Turboden 65-HRS unit is considered as representative of the organic Rankine cycle technology. Air bottoming cycles are analyzed and optimal design pressure ratios are selected. We also study a one pressure level steam Rankine cycle employing the once-through heat recovery steam generator without bypass stack. We compare the three technologies considering the combined cycle thermal efficiency, the weight, the net present value, the profitability index and payback time. Both incomes related to CO2 taxes and natural gas savings are considered. The results indicate that the Turboden 65-HRS unit is the optimal technology, resulting in a combined cycle thermal efficiency of 41.5% and a net present value of around 15 M$, corresponding to a payback time of approximately 4.5 years. The total weight of the unit is expected to be around 250 ton. The air bottoming cycle without intercooling is also a possible alternative due to its low weight (76 ton) and low investment cost (8.8 M$). However, cycle performance and profitability index are poorer, 12.1% and 0.75. Furthermore, the results suggest that the once-trough single pressure steam cycle has a combined cycle thermal efficiency of 40.8% and net present value of 13.5 M$. The total weight of the steam Rankine cycle is estimated to be around 170 ton.

scholarly journals Combined Closed Cycle (C3) Systems for Underwater Power Generation

1992 ◽  
Author(s):  
Aristide Massardd ◽  
Gian Marid Arnulfi
Keyword(s):  
Power Generation ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Combined Cycle ◽  
Working Fluid ◽  
Mass Reduction ◽  
Efficiency Increase

In this paper three Closed Combined Cycle (C3) systems for underwater power generation are analyzed. In the first, the waste heat rejected by a Closed Brayton Cycle (CBC) is utilized to heat the working fluid of a bottoming Rankine Cycle; in the second, the heat of a primary energy loop fluid is used to heat both CBC and Rankine cycle working fluids; the third solution involves a Metal Rankine Cycle (MRC) combined with an Organic Rankine Cycle (ORC). The significant benefits of the Closed Combined Cycle concepts, compared to the simple CBC system, such as efficiency increase and specific mass reduction, are presented and discussed. A comparison between the three C3 power plants is presented taking into account the technological maturity of all the plant components.

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