Techno‐economic assessment on the fuel flexibility of a commercial scale combined cycle gas turbine integrated with a CO2 capture plant

Post‐combustion carbon capture is a valuable technology, capable of being deployed to meet global CO2 emissions targets. The technology is mature and can be retrofitted easily with existing carbon emitting energy generation sources, such as natural gas combined cycles. This study investigates the effect of operating a natural gas combined cycle plant coupled with carbon capture and storage while using varying fuel compositions, with a strong focus on the influence of the CO2 concentration in the fuel. The novelty of this study lies in exploring the technical and economic performance of the integrated system, whilst operating with different fuel compositions. The study reports the design of a natural gas combined cycle gas turbine and CO2 capture plant (with 30 wt% monoethanolamine), which were modelled using the gCCS process modelling application. The fuel compositions analysed were varied, with focus on the CO2 content increasing from 1% to 5%, 7.5% and 10%. The operation of the CO2 capture plant is also investigated with focus on the CO2 capture efficiency, specific reboiler duty and the flooding point. The economic analysis highlights the effect of the varying fuel compositions on the cost of electricity as well as the cost of CO2 avoided. The study revealed that increased CO2 concentrations in the fuel cause a decrease in the efficiency of the natural gas combined cycle gas turbine; however, rising the CO2 concentration and flowrate of the flue gas improves the operation of the capture plant at the risk of an increase in the flooding velocity in the column. The economic analysis shows a slight increase in cost of electricity for fuels with higher CO2 contents; however, the results also show a reduction in the cost of CO2 avoided by larger margins

Investigation of particle radiation and its effect on NO prediction in a pilot-scale facility for both air and oxy-coal combustion

Radiation heat transfer plays an important role in pulverised coal combustion, influencing the overall combustion efficiency, pollutant formation and flame ignition and propagation. In this paper, the radiation properties of the particles as well as gas property models on the overall influence of the prediction of the formation of NOx pollutants in a pulverised coal combustion have been investigated. The non-grey weighted sum of grey gases (WSGG) model has been employed to calculate the radiation of the gas phase coupled with the radiation interaction from the particulate phase. The Mie theory, as well as constant or linear models, have been employed to describe the particle radiative properties. The prediction results, calculated from the data from a 250 kW pilot scale combustion test facility (CTF), are compared against experimental measurements under air-fired condition and a range of oxyfuel conditions. The results show that the choice of radiation solution can have a considerable impact on the radiative heat transfer results, in which the Mie theory shows a significant improvement in the incident wall heat flux compared to the constant or linear models. Also, the more accurate solution employed for radiation of gases and particles considerably improves the NOx prediction in the flame region

Assessment of ethanol autoxidation as a drop-in kerosene and surrogates blend with a new modelling approach

Bioethanol has been considered as a more sustainable alternative for fossil fuels, and it has been used as a drop-in fuel mixture. In this paper, the autoxidation properties of real kerosene as well as single, binary and ternary surrogates with the presence of ethanol are investigated for the first time. A simplified python code is proposed to predict the pressure drop of the PetroOXY method that was used for assessing the fuel autoxidation properties. The experimental results show that the addition of an ethanol concentration reduces the induction period of real kerosene while increasing that of surrogate mixtures. Also, the maximum pressure during the PetroOXY test increases with the increase of ethanol concentration. The model is able to predict the induction period of ethanol accurately by employing an automated reaction mechanism generator. A strategy to increase the autoxidation stability of ethanol by adding 1 g/L antioxidant has been evaluated. The efficiency of the antioxidants for ethanol is in the following order: PY > Decalin > DTBP > Tetralin > BHT > MTBP > BHA > TBHQ > PG

Oscillating coal and biomass flames: A spectral and digital imaging approach for air and oxyfuel conditions

The transient nature of a flame can be quantified by performing spectral and oscillatory analysis of its parameters, such as the flame's luminance and temperature. This paper presents an assessment of the effect of an oxyfuel environment on the combustion of two different solid fuels, a high volatile bituminous coal and a white wood biomass, in a 250 kWth pilot-scale combustion test facility. A digital flame monitoring system was fitted to the experimental furnace, and was used to record high speed videos of the flame. Transient signals for both digital luminance and temperature were obtained after the instantaneous frames were extracted from the original videos. Spectral analysis was performed over the transient signal in order to analyse the temporal coherence of the flame through a weighted oscillation frequency value. An additional parameter, the oscillation index, which accounts for the amplitude of the oscillation of the flame, was computed to complement the information recovered from the flame. The oscillation trends obtained from these experiments assess the dynamic response of the flame to different combustion environments within the furnace. In general, it was found that oxyfuel flames showed a discernible temporal repeatability and a lower magnitude of the oscillation of their flame parameters, and therefore are registered as being more stable than their counterpart under air combustion conditions. In addition, the biomass flames exhibit less sensitivity to the oxyfuel combustion environment than what was found with coal, which may allow future oxy-biomass regimes to operate under a much wider envelop of firing conditions

Quantum Rotation of HCN and DCN in Helium-4

We present calculations of rotational absorption spectra of the molecules HCN and DCN in superfluid helium-4, using a combination of the Diffusion Monte Carlo method for ground state properties and an analytic many-body method (Correlated Basis Function theory) for the excited states. Our results agree with the experimentally determined effective moment of inertia which has been obtained from the $J=0\to 1$ spectral transition. The correlated basis function analysis shows that, unlike heavy rotors such as OCS, the J=2 and higher rotational excitations of HCN and DCN have high enough energy to strongly couple to rotons, leading to large shifts of the lines and accordingly to anomalous large spectroscopic distortion constants, to the emergence of roton-maxon bands, and to secondary peaks in the absorption spectra for J=2 and J=3.Comment: accepted by Phys. Rev. B; changes: included referee suggestions, removed typos, added 10 ref

Alterations to nuclear architecture and genome behavior in senescent cells.

The organization of the genome within interphase nuclei, and how it interacts with nuclear structures is important for the regulation of nuclear functions. Many of the studies researching the importance of genome organization and nuclear structure are performed in young, proliferating, and often transformed cells. These studies do not reveal anything about the nucleus or genome in nonproliferating cells, which may be relevant for the regulation of both proliferation and replicative senescence. Here, we provide an overview of what is known about the genome and nuclear structure in senescent cells. We review the evidence that nuclear structures, such as the nuclear lamina, nucleoli, the nuclear matrix, nuclear bodies (such as promyelocytic leukemia bodies), and nuclear morphology all become altered within growth-arrested or senescent cells. Specific alterations to the genome in senescent cells, as compared to young proliferating cells, are described, including aneuploidy, chromatin modifications, chromosome positioning, relocation of heterochromatin, and changes to telomeres

Climatic effects on sugarcane ripening under the influence of cultivars and crop age

The lack of information about the effects of cultivars, crop age and climate on the sugarcane (Saccharum ssp.) crop yield and quality has been the primary factor impacting the sugar-ethanol sector in Brazil. One of the processes about which we do not have a satisfactory understanding is sugarcane ripening and the effects of cultivars, crop age and climate on that. Sugarcane ripening is the process of sucrose accumulation in stalks, which is heavily influenced by several factors, mainly by climatic conditions such as air temperature and water deficits. Because it is a complex process, studies of the variables involved in sugarcane ripening can provide important information, resulting in a better use of commercial cultivars, bringing advantages to growers, processing units, breeding programs and scientific community. In this review, we discuss the available knowledge of the interaction between climate conditions and sugarcane ripening, under the influence of genotypic characteristics and crop age. In several studies, the main conclusion is that sugarcane ripening depends on a complex combination of climate variables, the genetic potential of cultivars and crop management. Soil moisture and air temperature are the primary variables involved in sugarcane ripening, and their combination stimulates the intensity of the process. In addition, the need for studies integrating the effects of climate on plant physiological processes and on the use of chemical agents to stimulate sugarcane ripening is highlighted

Liquid 4He: contributions to first principles theory of quantized vortices, thermohydrodynamic properties, and the lambda transition

Liquid 4He has been studied extensively for almost a century, but there are still a number of outstanding weak or missing links in our comprehension of it. This paper reviews some of the principal paths taken in previous research and then proceeds to fill gaps and create an integrated picture with more complete understanding through first principles treatment of a realistic model that starts with a microscopic, atomistic description of the liquid. Newly derived results for vortex cores and thermohydrodynamic properties for a two-fluid model are used to show that interacting quantized vortices may produce a lambda anomaly in specific heat near the superfluid transition where flow properties change. The nature of the order in the superfluid state is explained. Experimental support for new calculations is exhibited, and a unique specific heat experiment is proposed to test predictions of the theory. Relevance of the theory to modern research in cosmology, astrophysics, and Bose-Einstein condensates is discussed.Comment: 155 pages, 28 figure

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters