Air Bottoming Cycle: Use of Gas Turbine Waste Heat for Power Generation

1996 ◽  
Vol 118 (2) ◽  
pp. 359-368 ◽  
Author(s):  
O. Bolland ◽  
M. Fo̸rde ◽  
B. Ha˚nde

This paper presents a thermodynamic analysis of the Air Bottoming Cycle (ABC) as well as the results of a feasibility study for using the Air Bottoming Cycle for gas turbine waste heat recovery/power generation on oil/gas platforms in the North Sea. The basis for the feasibility study was to utilize the exhaust gas heat from an LM2500PE gas turbine. Installation of the ABC on both a new and an existing platform have been considered. A design reference case is presented, and the recommended ABC is a two-shaft engine with two compressor intercoolers. The compression pressure ratio was found optimal at 8:1. The combined gas turbine and ABC shaft efficiency was calculated to 46.6 percent. The LM2500PE gas turbine contributes with 36.1 percent while the ABC adds 10.5 percent points to the gas turbine efficiency. The ABC shaft power output is 6.6 MW when utilizing the waste heat of an LM2500PE gas turbine. A preliminary thermal and hydraulic design of the ABC main components (compressor, turbine, intercoolers, and recuperator) was carried out. The recuperator is the largest and heaviest component (45 tons). A weight and cost breakdown of the ABC is presented. The total weight of the ABC package was calculated to 154 metric tons, and the ABC package cost to 9.4 million US$. An economical examination for three different cases was carried out. The results show that the ABC alternative (LM2500PE + ABC) is economical, with a rather good margin, compared to the other alternatives. The conclusion is that the Air Bottoming Cycle is an economical alternative for power generation on both new platforms and on existing platforms with demand for more power.

2018 ◽  
Vol 58 (2) ◽  
pp. 719
Author(s):  
Lourens Jacobs ◽  
Nancy Nguyen ◽  
Ryan Beccarelli

Woodside is an Australian oil and gas company and a leading global operator of offshore gas platforms and onshore LNG processing facilities. It is a public company listed on the Australian Securities Exchange headquartered in Perth, Western Australia. Woodside operates the Goodwyn A gas platform on behalf of the North West Shelf (NWS) Project. Woodside assessed Li-ion battery technology and considered the technology mature and ready to be utilised on offshore and onshore operating assets. Woodside operates dedicated islanded gas turbine power generation at each of its onshore and offshore facilities. It was concluded that a large battery energy storage solution (BESS) can deliver several advantages if connected to such an islanded power generation system. The most significant benefit materialises by using a BESS as backup (or spinning reserve) for the gas turbine generators (GTGs). Woodside decided to pioneer the Li-ion BESS technology in a first of its kind application on the NWS Project offshore Goodwyn A gas platform. The Goodwyn A BESS is designed for a 1 MW power and 1 MWh energy capacity, which is considered sufficient to provide the spinning reserve for the Goodwyn A platform. Currently, Goodwyn A operates four 3.2 MW GTGs to provide a typical load of 7–8 MW, with one GTG providing the N+1 spinning reserve. When the BESS is connected to the power generation system, Goodwyn A will operate three GTGs, with the BESS proving the backup in case one of the GTGs trip. The BESS will provide the full 1 MW for a minimum of 1 h, which will give the operators enough time to start the standby GTG or adjust the facility loads (load shedding). The result will be a decrease in overall fuel gas consumption (due to better efficiencies on the remaining GTGs in operation) and a related reduction in CO2 emissions. The project supports the overall objective of the North West Shelf Project to improve the energy intensity of its facilities by 5% by 2020. Woodside believes that developing capability and experience on the installation of BESSs, using Goodwyn A as an early adopter, will facilitate similar and larger installations on other Woodside operated offshore and onshore assets. This is one of the technologies Woodside believes will play an important role to ensure a lower carbon future globally.


Author(s):  
Z. P. Tilliette

For power generation, steam cycles make an efficient use of medium temperature (•□ 300–600°C) heat sources. They can be adapted to dry cooling, higher power ratings and output increase in winter by addition of an ammonia bottoming cycle. Active development is carried out in this field by “Electricite de France.” It is shown that a satisfactory result, for heat sources of about 770°C, is obtained with a topping closed gas cycle of moderate power rating, rejecting its waste heat into the main steam cycle. Attention has to be paid to the gas turbine cycle waste heat recovery and to the coupling of the gas turbine and steam cycles. This concept drastically reduces the importance of new technology components.


Author(s):  
Hideto Moritsuka

In order to estimate the possibility to improve thermal efficiency of power generation use gas turbine combined cycle power generation system, benefits of employing the advanced gas turbine technologies proposed here have been made clear based on the recently developed 1500C-class steam cooling gas turbine and 1300C-class reheat cycle gas turbine combined cycle power generation systems. In addition, methane reforming cooling method and NO reducing catalytic reheater are proposed. Based on these findings, the Maximized efficiency Optimized Reheat cycle Innovative Gas Turbine Combined cycle (MORITC) Power Generation System with the most effective combination of advanced technologies and the new devices have been proposed. In case of the proposed reheat cycle gas turbine with pressure ratio being 55, the high pressure turbine inlet temperature being 1700C, the low pressure turbine inlet temperature being 800C, combined with the ultra super critical pressure, double reheat type heat recovery Rankine cycle, the thermal efficiency of combined cycle are expected approximately 66.7% (LHV, generator end).


Author(s):  
K. K. Botros ◽  
G. R. Price ◽  
R. Parker

Hybrid PSOFC/GT cycles consisting of pressurized solid oxide fuel cells integrated into gas turbine cycles are emerging as a major new power generation concept. These hybrid cycles can potentially offer thermal efficiencies exceeding 70% along with significant reductions in greenhouse gas and NOX emissions. This paper considers the PSOFC/GT cycle in terms of electrical and mechanical power generation with particular focus on gas pipeline companies interested in diversifying their assets into distributed electric generation or lowering pollutant emissions while more efficiently transporting natural gas. By replacing the conventional GT combustion chamber with an internally reformed PSOFC, electrical power is generated as a by-product while hot gases exiting the fuel cell are diverted into the gas turbine for mechanical power. A simple one-dimensional thermodynamic model of a generic PSOFC/GT cycle has shown that overall thermal efficiencies of 65% are attainable, whilst almost tripling the specific work (i.e. energy per unit mass of air). The main finding of this paper is that the amount of electric power generated ranges from 60–80% of the total power available depending on factors such as the system pressure ratio and degree of supplementary firing before the gas turbine. Ultimately, the best cycle should be based on the “balance of plant”, which considers factors such as life cycle cost analysis, business and market focus, and environmental emission issues.


Author(s):  
Rodger O. Anderson

The generation of electrical power is a complex matter that is dependent in part both on the anticipated demand and the actual amount of power required on the grid. Therefore, the amount of power being generated varies widely depending on the time of day, day of the week, and atmospheric conditions such as cold spells and heat waves. While the amount of power varies, it is recognized that maximum efficiencies are achieved by operating power generation systems at or near steady state conditions. With this in mind, there has been an increased use of gas turbine systems that may be quickly added online to the grid to provide additional power because gas turbine systems are typically well suited for being brought online quickly to provide spinning reserve or electrical generation. However, gas turbines are recognized as not being as efficient as other plant systems such as large steam plants because the gas turbine is an open cycle system where approximately 60 to 70 percent of the energy is lost as exhaust waste heat energy. One recognized method of increasing gas turbine efficiencies is to add a steam bottoming cycle to the exhaust system. However, these closed cycle systems are costly and they compromise the gas turbine’s quick starting capability. This paper discusses an open bottoming cycle that is simple, cost effective and well suited for peaking power generation service. It not only substantially improves the gas turbine simple cycle plant heat rate, but also provides the opportunity to greatly reduce the NOX emissions levels with the application of a low temperature SCR.


Author(s):  
R. Bhargava ◽  
M. Bianchi ◽  
G. Negri di Montenegro ◽  
A. Peretto

This paper presents a thermo-economic analysis of an intercooled, reheat (ICRH) gas turbine, with and without recuperation, for cogeneration applications. The optimization analyses of thermodynamic parameters have permitted to calculate variables, such as low-pressure compressor pressure ratio, high-pressure turbine pressure ratio and gas temperature at the waste heat recovery unit inlet while maximizing electric efficiency and “Energy Saving Index”. Subsequently, the economic analyses have allowed to evaluate return on the investment, and the minimum value of gross payout period, for the cycle configurations of highest thermodynamic performance. In the present study three sizes (100 MW, 20 MW and 5 MW) of gas turbines have been examined. The performed investigation reveals that the maximum value of electric efficiency and “Energy Saving Index” is achieved for a large size (100 MW) recuperated ICRH gas turbine based cogeneration system. However, a non-recuperated ICRH gas turbine (of 100 MW) based cogeneration system provides maximum value of return on the investment and the minimum value of gross payout period compared to the other gas turbine cycles, of the same size and with same power to heat ratio, investigated in the present study. A comprehensive thermo-economic analysis methodology, presented in this paper, should provide useful guidelines for preliminary sizing and selection of gas turbine cycle for cogeneration applications.


Author(s):  
Christophe Duwig ◽  
Björn Nyberg ◽  
Marcus Thern

Environmental and political concerns, together with new legislations, are pushing for a fuel shift in the power industry and more generally for many thermal applications. Adding to the coming decrease of oil and natural availability (or price increase), it opens avenues for new fuels. Among those, alcohols are strong candidates. In fact, short alcohols are easily produced and stored and require only moderate modifications of existing combustion systems. For example, operating an existing gas turbine (GT) on methanol requires moderate modifications (mainly in the combustion system). However, methanol can be used more efficiently. Unlike methane or other hydrocarbons that decompose at high temperature (1000K), methanol undergoes an endothermic decomposition at low temperatures (400K to 600K) to give CO and H2. It therefore opens avenue for coupling the GT with a chemical recuperation system. In other words, the methanol will be cracked using the waste heat of the flue gases with a gain in fuel heating value hence the original fuel is thermally upgraded. The present study will investigate the upgraded fuel combustion properties. The laminar flame speed of the upgraded fuel/air mixtures will be presented and compared to methane and methanol under conditions relevant to GT combustion. Several upgraded fuel compositions will be considered depending on the water content in the feed methanol. Further, we consider a recuperated micro GT (Turbec T100) based cycle fueled with methanol. The numerical study focuses on different thermodynamic cycles. Firstly, a reference case is considered assuming a direct fueled GT. Further, cycles including the cracker are studied keeping the power constant. The fuel efficiency gain due to the cracker will be investigated as function of the water content in the feed methanol. Finally, a case including CO2-removal will be presented and it will be shown that the cracker enables an efficient carbon capture and sequestration scheme.


Author(s):  
Jason John Dennis ◽  
Thomas Bexten ◽  
Nils Petersen ◽  
Manfred Wirsum ◽  
Patrick Preuster

Abstract One of the main challenges currently hindering the transition to energy systems based on renewable power generation is grid stability. To compensate for the volatility of wind- and solar-based power generation, storage facilities able to adapt to seasonal and short term differences in energy production and demand are required. Liquid Organic Hydrogen Carriers (LOHCs) represent a viable method of chemically binding elemental hydrogen, offering opportunities for largescale and safe energy storage. In times of energy shortage, flexible and dispatchable power generation technologies such as gas turbines can be fueled by hydrogen stored in this manner. Hydrogen can be released from its liquid carrier via an endothermic dehydrogenation reaction using waste heat provided by the gas turbine. This gaseous hydrogen can be supplied to the gas turbine combustion chamber using a hydrogen compressor. In the present study a steady state model is developed in order to analyse the heat-integrated combination of a 7.7 MW hydrogen-fired gas turbine and a H18-DBT/H0-DBT LOHC system. For the best-performing parameter set the effective storage density of the LOHC oil comes to 1.5 kWh/L. This value is situated in-between that of compressed hydrogen at 350 bar (1.01 kWh/L) and liquid hydrogen (2.33 kWh/L). Concurrently, the corresponding energy required for hydrogen compression reduces the overall system efficiency to 22.00 % (ηGT = 30.15%). The resulting optimal electricity yield, being a product of these two values, amounts to 0.33 kWhel/L.


1970 ◽  
Author(s):  
N. K. H. Scholz

The effect of the main design parameters of the aero gas turbine engine cycle, namely combustion temperature and compression pressure ratio, on the specific performance values is discussed. The resulting development trend has been of essential influence on the technology. Relevant approaches are outlined. The efforts relating to weight and manufacturing expense are also indicated. In the design of aero gas turbine engines increasing consideration is given to the specific flight mission requirements, such as for instance by the introduction of the by-pass principle. Therefore direct application of aero gas turbine engines for ship propulsion without considerable modifications, as has been practiced in the past, is not considered very promising for the future. Nevertheless, there are possibilities to take advantage of aero gas turbine engine developments for ship propulsion systems. Appropriate approaches are discussed. With the experience obtained from aero gas turbine engines that will enter service in the early seventies it should be possible to develop marine gas turbine engines achieving consumptions and lifes that are competitive with those of advanced diesel units.


Author(s):  
Daniele Fiaschi ◽  
Lidia Lombardi ◽  
Libero Tapinassi

The relatively innovative gas turbine based power cycles R-ATR and R-REF (Recuperative – Auto Thermal Reforming GT cycle and Recuperative – Reforming GT cycle) here proposed, are mainly aimed to allow the upstream CO2 removal by the natural gas fuel reforming. The 2nd part of the paper is dedicated to the R-REF cycle: the power unit is a Gas Turbine (GT), fuelled with reformed and CO2 cleaned gas, obtained by the addition of several sections to the simple GT cycle, mainly: • Reformer section (REF), where the reforming reactions of methane fuel with steam are accomplished: the necessary heat is supplied partially by the exhausts cooling and, partially, with a post–combustion. • Water Gas Shift Reactor (WGSR), where the reformed fuel is, shifted into CO2 and H2 with the addition of water. • CO2 removal unit for the CO2 capture from the reformed and shifted fuel. No water condensing section is adopted for the R-REF configuration. Between the main components, several heat recovery units are applied, together with GT Cycle recuperator, compressor intercooler and steam injection into the combustion chamber. The CO2 removal potential is close to 90% with chemical absorption by an accurate choice of amine solution blend: the heat demand for amine regeneration is completely self-sustained by the power cycle. The possibility of applying steam blade cooling (the steam is externally added) has been investigated: in these conditions, the RREF has shown efficiency levels close to 43–44%. High values of specific work have been observed as well (around 450–500 kJ/kg). The efficiency is slightly lower than that found for the R–ATR solution, and 2–3% lower than CRGTs with CO2 removal and steam bottoming cycle, not internally recuperated. If compared with these, the R-REF offers higher simplicity due to absence of the steam cycle, and can be regarded as an improvement to the simple GT. In this way, at least 5–6 points efficiency can be gained, together with high levels of CO2 removal. The effects of the reformed fuel gas composition, temperature and pressure on the amine absorption system for the CO2 removal have been investigated, showing the beneficial effects of increasing pressure (i.e. pressure ratio) on the specific heat demand.


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