Gas turbine power cycles for retrofitting and repowering coal plants with post-combustion carbon dioxide capture

A widely-proposed way to retrofit coal-fired power plants with post-combustion CO2 capture (PCC) is to supply all the electricity and heat required to operate the capture equipment from the existing steam cycle (an ‘integrated retrofit’), at the expense of a reduction in site power output. As an alternative, it is possible to add a gas turbine (GT) plant to maintain, or even increase, the net site power output. The GT can be integrated with the capture plant in various ways to supply all or part of the heat and power required for the capture and compression systems. But there is then the issue of how to capture the CO2 emissions from the added GT plant. In this study a novel retrofit configuration is proposed. The exhaust gas of the GT replaces part of the secondary air for the coal boiler and a common capture system is used for both coal- and natural gas-derived CO2. This new ‘GT flue gas windbox retrofit’ is based on the principles of previous hot windbox repowering proposals, with additional modifications to permit operation without extensive coal boiler modifications. To achieve this, the heat recovery steam generator (HRSG) attached to GT is designed to maintain the main steam turbine flow rates and temperatures, to compensate for a necessary reduction in coal feed rates, and this, with the GT output, maintains the net power output of the site A techno-economic analysis of coal plants retrofitted with GT power cycles shows that these ‘power matched’ retrofits can be competitive with integrated retrofits at lower natural gas prices (as is now the case in North America). In particular, the novel GT flue gas windbox retrofit provides a promising alternative for adapting integrated capture retrofits that are initially designed for flexible operation with zero to full (~90%) capture (as at the Boundary Dam 3 unit) for subsequent operation only with full capture. In this case the addition of a GT flue gas windbox retrofit will restore the full power output of the site with full CO2 capture and using the original capture plant. In general, techno-economic analysis shows that the economic performance of GT retrofit options depends on the site power export capacity. If there is no limit on power export then retrofits may advantageously also include an additional steam cycle, to give a combined cycle with the GT, otherwise retrofits with a single pressure HRSG producing process steam only are preferred

Carbon capture retrofit options with the on-site addition of gas turbine combined heat and power cycle

AbstractThis article examines the economic factors that may be important in determining the overall performance of coal plants retrofitted with an additional gas turbine combined heat and power cycle. A comparison is made with an integrated retrofit where steam is extracted from the power cycle

Maintaining the Power Output of An Existing Coal Plant with the Addition of CO 2 Capture: Retrofits Options With Gas Turbine Combined Cycle Plants

AbstractIt is likely that a significant number of existing pulverised coal-fired power plants will be retrofitted with post-combustion capture as part of a global rollout of carbon capture and storage. Previous studies have demonstrated that the energy penalty for post-combustion carbon dioxide (CO2) capture can be greatly minimised by effective integration of the capture system with the power cycle. Nevertheless, the power output of the site is, in most cases, reduced and the volume of electricity sales would drop. For other plants, the existing steam cycle may not be able to be integrated effectively for steam extraction, or space and access around/to the steam cycle may be impossible. As an alternative to steam extraction, it is possible to retrofit existing coal plants with a gas turbine combined cycle plant (CCGT) to maintain, or even increase, the site power output. The gas turbine can be integrated to the existing coal plant in various ways to supply all the heat, or a fraction of the heat, and the power required for the capture systems. An important consideration is whether carbon emissions from both, the combined cycle and the retrofitted coal plant are captured, or from the latter only.This paper examines these different options for carbon capture retrofits to existing coal plant and presents a novel configuration with the sequential combustion of gas turbine flue gas in the existing coal boiler while capturing carbon emissions from the combustion of coal and natural gas

Impact of moderate coronary atherosclerosis on long-term left ventricular remodeling after aortic valve replacement

Background: The role of coronary atherosclerosis (CA+) in ventricular remodeling after aortic valve replacement (AVR) for isolated aortic stenosis (AS) is not well defined. We sought to evaluate the impact of not revascularized moderate coronary atherosclerosis in long-term left ventricular (LV) remodeling after AVR. Methods: We assessed by coronariography the coronary artery disease in 66 patients referred for AVR and evaluated morphological and functional LV data by echocardiography both preoperatively and postoperatively (3 ± 1.2 years). Results: In patients without coronary atherosclerosis, hypertrophy regression was more intense and the absolute reverse remodeling was higher in LV mass index (–55.8 ± 36 g/m2 vs –28.4 ± 34 g/m2, p = 0.004), reduction of LV dimensions (LV end-diastolic diameter [LVEDD]: –4.1 ± 7.4 mm vs –2.2 ± 8.3 mm, p = 0.04), and regression of wall thickness (interventricular septum [IVS]: –3.3 ± 2.6 mm vs –1.6 ± 2.2 mm, p = 0.01; and posterior wall thickness [PWT]: –2.1 ± 2.1 mm vs 0.6 ± 2.1 mm, p = 0.012). Conclusions: After AVR for AS, not revascularized moderate coronary atherosclerosis determines a long-term lesser degree of LV hypertrophy regression and a worse absolute reverse remodeling of LV mass index, LVEDD, IVS and PWT. (Cardiol J 2011; 18, 3: 277–281

On the retrofitting and repowering of coal power plants with post-combustion carbon capture: An advanced integration option with a gas turbine windbox

Retrofitting a significant fraction of existing coal-fired power plants is likely to be an important part of a global rollout of carbon capture and storage. For plants suited for a retrofit, the energy penalty for post-combustion carbon capture can be minimised by effective integration of the capture system with the power cycle. Previous work on effective integration options has typically been focused on either steam extraction from the power cycle with a reduction of the site power output, or the supply of heat and electricity to the capture system via the combustion of natural gas, with little consideration for the associated carbon emissions. This article proposes an advanced integration concept between the gas turbine, the existing coal plant and post-combustion capture processes with capture of carbon emissions from both fuels. The exhaust gas of the gas turbine enters the existing coal boiler via the windbox for sequential combustion to allow capture in a single dedicated capture plant, with a lower flow rate and a higher CO2 concentration of the resulting flue gas. With effective integration of the heat recovery steam generator with the boiler, the existing steam cycle and the carbon capture process, the reference subcritical unit used in this study can be repowered with an electricity output penalty of 295 kWh/tCO2 – 5% lower than a conventional steam extraction retrofit of the same unit – and marginal thermal efficiency of natural gas combustion of 50% LHV – 5% point higher than in a configuration where the gas turbine has a dedicated capture unit

Sustained benefit of left ventricular remodelling after valve replacement for aortic stenosis

Background: Valve replacement for aortic stenosis (AS) determines negative ventricular remodelling. We used cross sectional and Doppler echocardiography to check how rapidly it occurs and to assess if these changes are sustained over time. Methods: We evaluated in 34 patients subjected to aortic valve replacement for AS morphological and functional (ejection fraction and E:A ratio) left ventricular data by echocardiography prior to surgery and 2 postoperative studies: early after surgery (pQ1) and at mid-term evolution (pQ2). Results: Left ventricular mass index was reduced at pQ1 (from 152 &#177; 47 g/m2 to 113 &#177; 31 g/m2; p < 0.01) as well as end-diastolic (from 51.3 mm to 48.3 mm; p < 0.03), end-systolic (from 32.2 mm to 29.4 mm; p < 0.02), interventricular septum (from 12.9 mm to 10.3 mm; p < 0.01), and posterior wall (from 12.5 mm to 11 mm; p < 0.01) dimensions. Left ventricular ejection fraction (from 61.2% to 65.2%; p < 0.04) and E:A ratio (from 0.94 to 0.98; p < 0.01) increased significantly at pQ1. There were no significant differences in measurements between pQ1 and pQ2. Conclusions: Aortic valve replacement surgery leads to a rapid negative left ventricular remodelling during the first 7 months, including a decrease in myocardial hypertrophy and an improvement in systolic and diastolic function. These beneficial hemodynamic changes are sustained for at least 3 years

Wpływ umiarkowanej miażdżycy tętnic wieńcowych na przebudowę lewej komory serca u chorych po wymianie zastawki aortalnej

Wstęp: Znaczenie miażdżycy tętnic wieńcowych (CA+) w procesie przebudowy lewej komory po wymianie zastawki aortalnej (AVR) z powodu izolowanej stenozy aortalnej (AS) jest wciąż przedmiotem badań. Celem pracy była ocena wpływu niepoddanych rewaskularyzacji umiarkowanych zmian miażdżycowych tętnic wieńcowych na odległy proces remodelingu lewej komory serca (LV) po AVR. Metody: Za pomocą koronarografii oceniono stopień nasilenia choroby wieńcowej u 66 pacjentów zakwalifikowanych do AVR i pozyskano dane echokardiograficzne dotyczące budowy i funkcji LV zarówno przed-, jak i pooperacyjnie (3 &#177; 1,2 roku). Wyniki: U pacjentów bez miażdżycy tętnic wieńcowych ustąpienie przerostu i całkowite odwrócenie remodelingu były większe niż w grupie chorych z miażdżycą, gdy porównano indeks masy LV (&#8211;55,8 &#177; 36 g/m2 v. &#8211;28,4 &#177; 34 g/m2; p = 0,004). Ponadto w grupie osób bez choroby wieńcowej obserwowano istotne zmniejszenie wymiarów LV [wymiar końcoworozkurczowy LV (LVEDD): &#8211;4,1 &#177; 7,4 mm v. &#8211;2,2 &#177; 8,3 mm; p = 0,04] oraz grubości ścian [przegrody międzykomorowej (IVS): &#8211;3,3 &#177; 2,6 mm v. &#8211;1,6 &#177; 2,2 mm; p = 0,01; i ściany tylnej (PWT): &#8211;2,1 &#177; 2,1 mm v. 0,6 &#177; 2,1 mm; p = 0,012]. Wnioski: Brak rewaskularyzacji umiarkowanych zmian miażdżycowych w nasierdziowych tętnicach wieńcowych u pacjentów poddanych AVR z powodu AS prowadzi w odległej obserwacji do zwolnienia procesu regresji przerostu lewej komory i zaburzenia odwrócenia remodelingu w analizie następujących parametrów: indeksu masy LV, LVEDD, IVS i PTW. (Folia Cardiologica Excerpta 2011; 6, 3: 162&#8211;167

Thalamic Foxp2 regulates output connectivity and sensory-motor impairments in a model of Huntington's Disease

Huntington's Disease (HD) is a disorder that affects body movements. Altered glutamatergic innervation of the striatum is a major hallmark of the disease. Approximately 30% of those glutamatergic inputs come from thalamic nuclei. Foxp2 is a transcription factor involved in cell differentiation and reported low in patients with HD. However, the role of the Foxp2 in the thalamus in HD remains unexplored.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. AG is a Ramón y Cajal fellow (RYC-2016–19466). This work was supported by grants from Ministerio de Ciencia e Innovación/ AEI/10.13039/501100011033/ and “FEDER”: AG: PID2021-122258OB-I00; MVSV: PID2020-112947RB-I00; AB: PID2019-105136RB-100; DT: PID2020-118120RB-I00; JA & MJR: PID2020-119386RB-100. Funded by H2020 Grant Agreement No. 945539 (Human Brain Project SGA3 to MVSV). IDIBAPS is funded by the CERCA program (Generalitat de Catalunya).Peer reviewe

X-ray tests of the ATHENA mirror modules in BEaTriX: from design to reality

The BEaTriX (Beam Expander Testing X-ray) facility is now operative at the INAF-Osservatorio Astronomico Brera (Merate, Italy). This facility has been specifically designed and built for the X-ray acceptance tests (PSF and Effective Area) of the ATHENA Silicon Pore Optics (SPO) Mirror Modules (MM). The unique setup creates a parallel, monochromatic, large X-ray beam, that fully illuminates the aperture of the MMs, generating an image at the ATHENA focal length of 12 m. This is made possible by a microfocus X-ray source followed by a chain of optical components (a paraboloidal mirror, 2 channel cut monochromators, and an asymmetric silicon crystal) able to expand the X-ray beam to a 6 cm × 17 cm size with a residual divergence of 1.5 arcsec (vertical) × 2.5 arcsec (horizontal). This paper reports the commissioning of the 4.5 keV beam line, and the first light obtained with a Mirror Module