Browsing by Author "Di Lorenzo, Giuseppina"
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Item Open Access Aeroderivative gas turbine back-up capability with compressed air injection(Elsevier, 2020-08-08) Abudu, Kamal; Igie, Uyioghosa; Roumeliotis, Ioannis; Szymanski, Artur; Di Lorenzo, GiuseppinaThe transition to more renewable energy sources of power generation is associated with grid instability and the need for backup power, due to their intermittency. This provides an opportunity for gas turbine engines, especially the aeroderivative (AD) types that generally have higher ramp rates than heavy-duty engines. Nonetheless, higher ramp rates are still necessary to meet more stringent grid requirements, with increased renewables subscription. The study examines ramp rate improvements and performance enhancement through compressed air injection at the back of the high-pressure compressor (HPC). Two configurations of AD engines are considered in the investigation. In-house gas turbine performance simulation software has been used to simulate the steady-state and transient operations for design and off-design performance. Compressed air injection in the study is facilitated by an assumed compressed air storage or an external compressor. The steady-state analysis for power augmentation shows that for the two-spool engine with fixed speed low-pressure compressor (LPC), a 16% increase in power is obtained with 8% of flow injection. The other engine that is intercooled and consists of a variable speed LPC with power turbine shows a 21% increase in power for the same injection amount. Above 8% injection, the HPC of both engines tends towards an adverse rise in pressure ratio. However, up to 15% of flow injection is allowed before the surge point. It is seen generally that the operating point of the LPC moves away from surge, while the opposite is the case for the HPC. For transient simulations focused on ramp rates, the better improvements are shown for the intercooled engine that runs at variable speed. This is a ramp rate improvement of 100% with air injection, while that of the other engine increases by 85%Item Open Access Assessing biomass-fired gas turbine power plants: a techno-economic and environmental perspective(Cranfield University, 2013-07) Ihiabe, Daniel; Di Lorenzo, Giuseppina; Pilidis, PericlesFossil fuels continue to deplete with use as they are irreplaceable. In addition, the environmental impact with the continuous use of these conventional fuels has generated global concern due to the production of harmful emission gases. An alternative source of energy has become inevitable. Technological advancements in the area of biomass use for both aviation and power generation are at different levels of development. There is however the need for an integrated approach to assess gas turbine engine behaviour in terms of performance, emission and economics when they are running on biofuels. The current research work is concerned with finding alternative fuel resources for use on stationary gas turbine engines for power generation with the necessary identification of suitable biofuels using a multidisciplinary approach. A techno-economic, environmental and risk assessment (TERA) model comprising the performance, emissions, economics and risk modules has been developed. There had been several simulations of two gas turbine engines (GTEs) to ascertain the effects of both ambient and operating conditions and the effect of fuel types on the engines. These simulations were done with the use of an in-house code-the Turbomatch and a code developed for the steam cycle which is employed for the combined cycle simulation. Cont/d.Item Open Access Engineering management of gas turbine power plant co2 for microalgae biofuel production(Cranfield University Press, 2013-09-19) Mathew, Domoyi; Pilidis, Pericles; Di Lorenzo, GiuseppinaFossil fuel accounts for over 80% of the world`s primary energy, particularly in areas of transportation, manufacturing and domestic heating. However, depletion of fossil reserves, frequent threats to the security of fossil fuel supply, coupled with concerns over emissions of greenhouse gases associated with fossil fuel use has motivated research towards developing renewable and sustainable sources for energy fuels. Consequently, the use of microalgae culture to convert CO2 from power plants flue gases into biomass that are readily converted into biofuel offers a window of opportunities to enhance, compliment or replace fossil- fuel-use. Interest in the use of microalgae biomass for biofuel production is high as it affords the potential for power plant CO2 sequestration – (1kg of dry algae biomass uses about 1.83kg CO2). Similarly, its capacity to utilise nutrients from a variety of wastewater, sets it apart from other biomass resources. These outlined benefits all emphasis the need for extended R&D efforts to advance commercial microalgae biofuel production. The paper is aimed at investigating the environmental performance of the microalgae biofuel production process using LCA.Item Open Access Gas Turbine Application to CO2 Pipeline: A Techno-Economic and Environmental Risk Analysis(Cranfield University, 2014-12) El-Suleiman, Abdussalam; Pilidis, Pericles; Di Lorenzo, GiuseppinaGas Turbines (GTs) are used extensively in pipelines to compress gas at suitable points. The primary objective of this study is to look at CO2 return pipelines and the close coupling of the compression system with advanced prime mover cycles. Adopting a techno-economic and environmental risk analysis (TERA) frame work, this study conducts the modelling and evaluation of CO2 compression power requirements for gas turbine driven equipment (pump and compressor). The author developed and validated subroutines to implement variable stators in an in-house GT simulation code known as Variflow in order to enhance the off-design performance simulation of the code. This modification was achieved by altering the existing compressor maps and main program algorithm of the code. Economic model based on the net present value (NPV) method, CO2 compressibility factor model based on the Peng-Robinson equation of state and pipeline hydraulic analysis model based on fundamental gas flow equation were also developed to facilitate the TERA of selected GT mechanical drives in two case scenarios. These case scenarios were specifically built around Turbomatch simulated GT design and off-design performance which ensure that the CO2 is introduced into the pipeline at the supercritical pressure as well as sustain the CO2 pressure above a minimum designated pressure during transmission along an adapted real life pipeline profile. The required compression duty for the maximum and minimum CO2 throughput as well as the operation site ambient condition, guided the selection of two GTs of 33.9 MW and 9.4 MW capacities. At the site ambient condition, the off design simulations of these GTs give an output of 25.9 MW and 7.6 MW respectively. Given the assumed economic parameters over a plant life of 25 years, the NPV for deploying the 33.9 MW GT is about £13.9M while that of the 9.4 MW GT is about £1.2M. The corresponding payback periods (PBPs) were 3 and 7 years respectively. Thus, a good return on investment is achieved within reasonable risk. The sensitivity analysis results show a NPV of about £19.1M - £24.3M and about £3.1M - £4.9M for the 33.9 MW and 9.4 MW GTs respectively over a 25 - 50% fuel cost reduction. Their PBPs were 3 - 2 years and 5 - 4 years respectively. In addition, as the CO2 throughput drops, the risk becomes higher with less return on investment. In fact, when the CO2 throughput drops to a certain level, the investment becomes highly unattractive and unable to payback itself within the assumed 25 years plant life. The hydraulic analysis results for three different pipe sizes of 24, 14 and 12¾ inch diameters show an increase in pressure drop with increase in CO2 throughput and a decrease in pressure drop with increase in pipe size for a given throughput. Owing to the effect of elevation difference, the 511 km long pipeline profile gives rise to an equivalent length of 511.52 km. Similarly, given the pipeline inlet pressure of 15 MPa and other assumed pipeline data, the 3.70 MTPY (0.27 mmscfd) maximum average CO2 throughput considered in the 12¾ inch diameter pipeline results in a delivery pressure of about 15.06 MPa. Under this condition, points of pressure spikes above the pipeline maximum operating allowable pressure (15.3 MPa) were obtained along the profile. Lowering the pipeline operating pressure to 10.5 MPa gives a delivery pressure of about 10.45 MPa within safe pressure limits. At this 10.5 MPa, over a flat pipeline profile of same length, the delivery pressure is about 10.4 MPa. Thus, given the operating conditions for the dense phase CO2 pipeline transmission and the limit of this study, it is very unlikely that a booster station will be required. So also, compressing the CO2 to 15 MPa may no longer be necessary; which eliminates the need of combining a compressor and pump for the initial pressure boost in order to save power. This is because, irrespective of the saving in energy, the increase in capital cost associated with obtaining a pump and suitable driver far outweighs the extra expense incurred in acquiring a rated GT mechanical drive to meet the compression duty.Item Open Access Gas turbine compressor washing economics and optimisation using genetic algorithm(American Society of Mechanical Engineers (ASME), 2022-08-09) Musa, Gali; Igie, Uyioghosa; Di Lorenzo, Giuseppina; Alrashed, Mosab; Navaratne, RukshanStudies have shown that online compressor washing of gas turbine engines slows down the rate of fouling deterioration during operation. However, for most operators, there is a balancing between the performance improvements obtained and the investment (capital and recurring cost). Washing the engine more frequently to keep the capacity high is a consideration. However, this needs to be addressed with expenditure over the life of the washing equipment rather than a simple cost-benefit analysis. The work presented here is a viability study of online compressor washing for 17 gas turbine engines ranging from 5.3 to 307MW. It considers the nonlinear cost of the washing equipment related to size categories, as well as nonlinear washing liquid consumption related to the variations in engine mass flows. Importantly, the respective electricity break-even selling price of the respective engines was considered. The results show that for the largest engine, the return of investment is 520% and the dynamic payback time of 0.19 years when washing every 72 hours. When this is less frequent at a 480-hour interval, the investment return and payback are 462% and 0.22 years. The optimisation study using a multi-objective genetic algorithm shows that the optimal washing is rather a 95-hour interval. For the smallest engine, the investment was the least viable for this type of application.Item Open Access Improving microalgae biofuel production: an engineering management approach(Cranfield University, 2014-07) Mathew, Domoyi Castro; Di Lorenzo, Giuseppina; Pilidis, PericlesThe use of microalgae culture to convert CO2 from power plant flue gases into biomass that are readily converted into biofuels offers a new frame of opportunities to enhance, compliment or replace fossil-fuel-use. Apart from being renewable, microalgae also have the capacity to utilise materials from a variety of wastewater and the ability to yield both liquid and gaseous biofuels. However, the processes of cultivation, incorporation of a production system for power plant waste flue gas use, algae harvesting, and oil extraction from the biomass have many challenges. Using SimaPro software, Life cycle Assessment (LCA) of the challenges limiting the microalgae (Chlorella vulgaris) biofuel production process was performed to study algae-based pathway for producing biofuels. Attention was paid to material use, energy consumed and the environmental burdens associated with the production processes. The goal was to determine the weak spots within the production system and identify changes in particular data-set that can lead to and lower material use, energy consumption and lower environmental impacts than the baseline microalgae biofuel production system. The analysis considered a hypothetical transesterification and Anaerobic Digestion (AD) transformation of algae-to- biofuel process. Life cycle Inventory (LCI) characterisation results of the baseline biodiesel (BD) transesterification scenario indicates that heating to get the biomass to 90% DWB accounts for 64% of the total input energy, while electrical energy and fertilizer obligations represents 19% and 16% respectively. Also, Life Cycle Impact Assessment (LCIA) results of the baseline BD production scenario show high proportional contribution of electricity and heat energy obligations for most impact categories considered relative to other resources. This is attributed to the concentration/drying requirement of algae biomass in order to ease downstream processes of lipid extraction and subsequent transesterification of extracted lipids into BD. Thus, four prospective alternative production scenarios were successfully characterised to evaluate the extent of their impact scenarios on the production system with regards to lowering material use, lower energy consumption and lower environmental burdens than the standard algae biofuel production system. A 55.3% reduction in mineral use obligation was evaluated as the most significant impact reduction due to the integration of 100% recycling of production harvest water for the AD production system. Recycling also saw water demand reduced from 3726 kg (freshwater).kgBD- 1 to 591kg (freshwater).kgBD- 1 after accounting for evaporative losses/biomass drying for the BD transesterification production process. Also, the use of wastewater/sea water as alternative growth media for the BD production system, indicated potential savings of: 4.2 MJ (11.8%) in electricity/heat obligation, 10.7% reductions for climate change impact, and 87% offset in mineral use requirement relative to the baseline production system. Likewise, LCIA characterisation comparison results comparing the baseline production scenarios with that of a set-up with co-product economic allocation consideration show very interesting outcomes. Indicating -12 MJ surplus (-33%) reductions for fossil fuels resource use impact category, 52.7% impact reductions for mineral use impact and 56.6% reductions for land use impact categories relative to the baseline BD production process model. These results show the importance of allocation consideration to LCA as a decision support tool. Overall, process improvements that are needed to optimise economic viability also improve the life cycle environmental impacts or sustainability of the production systems. Results obtained have been observed to agree reasonably with Monte Carlo sensitivity analysis, with the production scenario proposing the exploitation of wastewater/sea water to culture algae biomass offering the best result outcome. This study may have implications for additional resources such as production facility and its construction process, feedstock processing logistics and transport infrastructure which are excluded. Future LCA study will require extensive consideration of these additional resources such as: facility size and its construction, better engineering data for water transfer, combined heat and power plant efficiency estimates and the fate of long-term emissions such as organic nitrogen in the AD digestate. Conclusions were drawn and suggestions proffered for further study.Item Open Access Life cycle evaluation of an intercooled gas turbine plant used in conjunction with renewable energy(Elsevier, 2016-08-12) Isaiah, Thank-God; Dabbashi, Siddig; Bosak, Dawid; Sampath, Suresh; Di Lorenzo, Giuseppina; Pilidis, PericlesThe life cycle estimation of power plants is important for gas turbine operators. With the introduction of wind energy into the grid, gas turbine operators now operate their plants in Load–Following modes as back-ups to the renewable energy sources which include wind, solar, etc. The motive behind this study is to look at how much life is consumed when an intercooled power plant with 100 MW power output is used in conjunction with wind energy. This operation causes fluctuations because the wind energy is unpredictable and overtime causes adverse effects on the life of the plant – The High Pressure Turbine Blades. Such fluctuations give rise to low cycle fatigue and creep failure of the blades depending on the operating regime used. A performance based model that is capable of estimating the life consumed of an intercooled power plant has been developed. The model has the capability of estimating the life consumed based on seasonal power demands and operations. An in-depth comparison was undertaken on the life consumed during the seasons of operation and arrives at the conclusion that during summer, the creep and low cycle life is consumed higher than the rest periods. A comparison was also made to determine the life consumed between Load–Following and stop/start operating scenarios. It was also observed that daily creep life consumption in summer was higher than the winter period in-spite of having lower average daily operating hours in a Start–Stop operating scenario.Item Open Access Life-cycle assessment of self-generated electricity in Nigeria and Jatropha biodiesel as an alternative power fuel(Elsevier, 2017-06-21) Somorin, Tosin Onabanjo; Di Lorenzo, Giuseppina; Kolios, Athanasios J.Insufficient available energy has limited the economic growth of Nigeria. The country suffers from frequent power outages, and inconvenient black–outs while residents and industries are forced to depend on self-generated electricity. Life-cycle assessment methodology was used to assess the environmental burdens associated with self-generated electricity (SGE) and proposed embedded power generation in Nigeria. The study shows that SGE from 5 kVA diesel generators contributes to greenhouse gas (GHG) emissions of 1625 kg CO2 eq./MWh, along with other environmental burdens. Based on a point estimate of diesel electric generators in Nigeria, SGE can contribute 389 million tonnes CO2 eq. to climate change every year. This can reposition Nigeria as one of the top 20 emitters of CO2 globally. A mandatory diesel fuel displacement with Jatropha biodiesel can reduce annual GHG emissions from SGE by 76% provided combined cycle power plants are adopted for embedded power generation. The magnitude of these benefits would depend on material inputs, seed yield as well as the environmental status of the reference fuel. Minimal use of fertilizers, chemicals and resources and fossil fuel substitution with renewable options can minimize adverse environmental burdens.Item Open Access Process modelling and simulation of degradation of 2-amino-2-methyl-1-propanol (AMP) capture plant(Elsevier, 2017-08-18) Osagie, Ebuwa; Biliyok, Chechet; Di Lorenzo, Giuseppina; Manovic, VasilijeThe presence of contaminants in the flue gas stream such as O2, CO2, SOX, and NOX can cause solvent degradation in solvent-based CO2 capture processes. In this study, the major degradation products reactions of the AMP-based CO2 capture process has been included in the Aspen Plus® V8.4 simulation software using equilibrium reactions. Assessing the solvent degradation, solvent concentration and flowrate were varied. The results showed that the AMP losses reduced by decreasing solvent flowrate and concentration. Largest energy savings are observed when increasing concentration up to 34 wt. %.Item Open Access Selective-exhaust gas recirculation for CO2 capture using membrane technology(Elsevier, 2017-11-10) Russo, Giuseppe; Prpich, George; Anthony, Edward J.; Montagnaro, Fabio; Jurado Pontes, Nelia; Di Lorenzo, Giuseppina; Darabkhani, Hamidreza GohariMembranes can potentially offer low-cost CO2 capture from post-combustion flue gas. However, the low partial pressure of CO2 in flue gases can inhibit their effectiveness unless methods are employed to increase their partial pressure. Selective-Exhaust Gas Recirculation (S-EGR) has recently received considerable attention. In this study, the performance of a dense polydimethylsiloxane (PDMS) membrane for the separation of CO2/N2 binary model mixtures for S-EGR application was investigated using a bench-scale experimental rig. Measurements at different pressures, at different feeding concentrations and with nitrogen as sweep gas revealed an average carbon dioxide permeability of 2943 ± 4.1%RSD Barrer. The bench-scale membrane module showed high potential to separate binary mixtures of N2 and CO2 containing 5–20% CO2. The permeability was slightly affected by feed pressures ranging from 1 to 2.4 bar. Furthermore, the separation selectivity for a CO2/N2 mixture of 10%/90% (by volume) reached a maximum of 10.55 at 1.8 bar. Based on the results from the bench-scale experiments, a pilot-scale PDMS membrane module was tested for the first time using a real flue gas mixture taken from the combustion of natural gas. Results from the pilot-scale experiments confirmed the potential of the PDMS membrane system to be used in an S-EGR configuration for capture of CO2.Item Open Access Techno-economic and environmental assessment of gas turbines utilizing biofuels(Cranfield University, 2015-03) Onabanjo, Tosin; Di Lorenzo, GiuseppinaThe continued global reliance on fossil fuels with impact on resource depletion, human health, atmospheric pollution and environmental degradation has necessitated a global drive to integrate renewable fuels such as biodiesels. Biodiesels are described as “fuels composed of fatty acid methyl or ethyl esters and obtained from vegetable oils or animal fats”. Their use in energy generation could diversify the world’s energy mix, reduce fossil fuel dependence, reduce emissions and energy cost to bring about other economic benefits, especially for developing economies and rural communities with lack of adequate access to modern energy. A techno-economic and environmental life cycle assessment is however required to ensure that these fuels are fit for use in engines and meet any regulatory standard and sustainability criteria. This thesis has evaluated the use of Jatropha- and microalgae-biodiesel for power generation in two industrial gas turbines with open and combined cycle configuration. This was achieved using a techno-economic and environmental life cycle impact assessment framework. Comparative fuel assessments have been carried out between biodiesels and fossil fuels. Furthermore, the concept of microbial fuel degradation was examined in gas turbines. The thesis have identified Jatropha biodiesel as a worthwhile substitute for conventional diesel fuel, because it has close performance and emission characteristics to conventional diesel fuel with added advantage of being renewable. The consequent displacement of conventional diesel fuel with Jatropha biodiesel has significant environmental benefits. For economic viability and sustainability of gas turbine operated power plants, energy producers require a minimum monetary amount to recover the added cost of operating 100% Jatropha biodiesel. Other integration mechanisms are also available for utilizing the fuel in engines without compromising on plant’s economic performance. In worst case scenarios, where there are no government incentives, local conditions such as high life cycle cost of electricity, open opportunities for distributed and independent power generation from renewable fuels like Jatropha-biodiesel. Furthermore, this thesis has identified salient energy conversion processes that occur in gas turbine fuels, especially with biodiesels and developed a bio-mathematical model, Bio-fAEG to simulate these processes in gas turbines. This platform is a first step in quantifiable assessment and could enable a better understanding of microbial initiated processes.Item Open Access Techno-economic evaluation of the 2-amino-2-methyl-1-propanol (AMP) process for CO2 capture from natural gas combined cycle power plant(Elsevier, 2018-02-04) Osagie, Ebuwa; Biliyok, Chechet; Di Lorenzo, Giuseppina; Hanak, Dawid P.; Manovic, VasilijeIt is widely accepted that emissions of CO2, which is a major greenhouse gas, are the primary cause of climate change. This has led to the development of carbon capture and storage (CCS) technologies in which CO2 is captured from large-scale point sources such as power plants. However, retrofits of carbon capture plants result in high efficiency penalties, which have been reported to fall in the range of 7–12% points in the case of post-combustion capture from natural gas-fired power plants. Therefore, a reduction of these efficiency losses is a high priority in order to deploy CCS at a large scale. At the moment, chemical solvent scrubbing using amines, such as monoethanolamine (MEA), is considered as the most mature option for CO2 capture from fossil fuel-fired power plants. However, due to high heat requirements for solvent regeneration, and thus high associated efficiency penalties, the use of alternative solvents has been considered to reduce the energy demand. In this study, a techno-economic assessment of the post-combustion CO2 capture process using 2-amino-2-methyl-1-propanol (AMP) for decarbonisation of a natural gas combined cycle (NGCC) power plant was performed. The thermodynamic assessment revealed that the AMP-based process resulted in 25.6% lower reboiler duty compared to that of the MEA-based process. This was primarily because the AMP solvent can be regenerated at a higher temperature (140 °C) and pressure (3.5 bar) compared to that of MEA (120 °C and 1.8 bar). Furthermore, the efficiency penalty due to the retrofit of the AMP-based process with the natural gas combined cycle power plant was estimated to be 7.1% points, compared to 9.1% points in the case of integration with the MEA-based process. Regardless of the superior thermodynamic performance, the economic performance of the AMP-based process was shown to be better than that of the MEA-based process only for make-up rates below 0.03%. Therefore, use of AMP as a solvent in chemical solvent scrubbing may not be the most feasible option from the economic standpoint, even though it can significantly reduce the efficiency penalty associated with CO2 capture from NGCCs.