A parametric study of the impact of membrane materials and process operating conditions on carbon capture from humidified flue gas

2013 ◽  
Vol 431 ◽  
pp. 139-155 ◽  
Author(s):  
Bee Ting Low ◽  
Li Zhao ◽  
Timothy C. Merkel ◽  
Michael Weber ◽  
Detlef Stolten
Keyword(s):  
Flue Gas ◽  
Parametric Study ◽  
Carbon Capture ◽  
Operating Conditions ◽  
Membrane Materials ◽  
The Impact

Optimisation of CO Turndown for an Axially Staged Gas Turbine Combustor

2020 ◽  
Author(s):  
Jacob E. Rivera ◽  
Robert L. Gordon ◽  
Mohsen Talei ◽  
Gilles Bourque
Keyword(s):  
Residence Time ◽  
Parametric Study ◽  
Gas Turbines ◽  
Flow Reactor ◽  
Operating Conditions ◽  
Independent Effect ◽  
Inlet Temperature ◽  
Operating Characteristics ◽  
Two Stage ◽  
The Impact

Abstract This paper reports on an optimisation study of the CO turndown behaviour of an axially staged combustor, in the context of industrial gas turbines (GT). The aim of this work is to assess the optimally achievable CO turndown behaviour limit given system and operating characteristics, without considering flow-induced behaviours such as mixing quality and flame spatial characteristics. To that end, chemical reactor network modelling is used to investigate the impact of various system and operating conditions on the exhaust CO emissions of each combustion stage, as well as at the combustor exit. Different combustor residence time combinations are explored to determine their contribution to the exhaust CO emissions. The two-stage combustor modelled in this study consists of a primary (Py) and a secondary (Sy) combustion stage, followed by a discharge nozzle (DN), which distributes the exhaust to the turbines. The Py is modelled using a freely propagating flame (FPF), with the exhaust gas extracted downstream of the flame front at a specific location corresponding to a specified residence time (tr). These exhaust gases are then mixed and combusted with fresh gases in the Sy, modelled by a perfectly stirred reactor (PSR) operating within a set tr. These combined gases then flow into the DN, which is modelled by a plug flow reactor (PFR) that cools the gas to varying combustor exit temperatures within a constrained tr. Together, these form a simplified CRN model of a two-stage, dry-low emissions (DLE) combustion system. Using this CRN model, the impact of the tr distribution between the Py, Sy and DN is explored. A parametric study is conducted to determine how inlet pressure (Pin), inlet temperature (Tin), equivalence ratio (ϕ) and Py-Sy fuel split (FS), individually impact indicative CO turndown behaviour. Their coupling throughout engine load is then investigated using a model combustor, and its effect on CO turndown is explored. Thus, this aims to deduce the fundamental, chemically-driven parameters considered to be most important for identifying the optimal CO turndown of GT combustors. In this work, a parametric study and a model combustor study are presented. The parametric study consists of changing a single parameter at a time, to observe the independent effect of this change and determine its contribution to CO turndown behaviour. The model combustor study uses the same CRN, and varies the parameters simultaneously to mimic their change as an engine moves through its steady-state power curve. The latter study thus elucidates the difference in CO turndown behaviour when all operating conditions are coupled, as they are in practical engines. The results of this study aim to demonstrate the parameters that are key for optimising and improving CO turndown.

Numerical Characterization of a Novel Staged Combustion Concept Applied to Oxy-Fuel Carbon Capture Technology

2011 ◽  
Author(s):  
Adrian Goanta ◽  
Jan-Peter Bohn ◽  
Maximilian Blume ◽  
Xinmeng Li ◽  
Hartmut Spliethoff
Keyword(s):  
Flue Gas ◽  
Carbon Capture ◽  
Co2 Concentration ◽  
Operating Conditions ◽  
Major Drawback ◽  
Numerical Characterization ◽  
Recent Developments ◽  
Combustion Technology ◽  
Experimental Values

In oxy-combustion the fuel is burnt in a mixture of oxygen and recirculated flue gas to keep the temperature inside the furnace to levels similar to conventional combustion. This eliminates the atmospheric nitrogen from the process, leading to a flue gas consisting mainly of carbon dioxide and water vapor. Further on, the CO2 can be separated for storage purposes. A major drawback of the conventional oxy-fuel combustion technology consists in the high amount of flue gas that has to be recirculated in order to control the temperature level inside the furnace. A novel oxy-fuel firing concept based on a combination of pulverized coal burners operating under non-stoichiometric conditions is investigated as a solution for lowering the necessary flue gas recirculation rate, while keeping the temperature inside the furnace at feasible levels. This paper presents a numerical analysis of the most relevant aspects for this new firing concept, such as process specifics and limitations, burner design criteria, aerodynamic characterization of the near burner zone, flame ignition and temperature. First the process is defined via thermodynamic calculations which are necessary to establish the operating conditions and to generate sets of parameters for the design phase of the burners. Subsequently the parameters generated in the first phase are used as boundary conditions for the design of the burners via CFD simulations. The CFD code used in this study is updated for oxy-firing conditions with the recent developments in terms of gas phase reactions, char conversion modeling and radiative heat transfer in high temperature atmospheres with elevated CO2 concentration. Additionally, the most relevant aspects regarding the validation of the CFD code against in-flame experimental values are presented and discussed. The simulations show good agreement with the averaged experimental data collected along the flame centerline.

scholarly journals Improving the Carbon Capture Efficiency for Gas Power Plants through Amine-Based Absorbents

2020 ◽  
Vol 13 (1) ◽  
pp. 72
Author(s):  
Saman Hasan ◽  
Abubakar Jibrin Abbas ◽  
Ghasem Ghavami Nasr
Keyword(s):  
Climate Change ◽  
Flue Gas ◽  
Carbon Capture ◽  
Power Plants ◽  
Environmental Concern ◽  
Co2 Reduction ◽  
Operating Conditions ◽  
Circulation Rate ◽  
Co2 Removal ◽  
Reduction Of Co2

Environmental concern for our planet has changed significantly over time due to climate change, caused by an increasing population and the subsequent demand for electricity, and thus increased power generation. Considering that natural gas is regarded as a promising fuel for such a purpose, the need to integrate carbon capture technologies in such plants is becoming a necessity, if gas power plants are to be aligned with the reduction of CO2 in the atmosphere, through understanding the capturing efficacy of different absorbents under different operating conditions. Therefore, this study provided for the first time the comparison of available absorbents in relation to amine solvents (MEA, DEA, and DEA) CO2 removal efficiency, cost, and recirculation rate to achieve Climate change action through caron capture without causing absorbent disintegration. The study analyzed Flue under different amine-based solvent solutions (monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA)), in order to compare their potential for CO2 reduction under different operating conditions and costs. This was simulated using ProMax 5.0 software modeled as a simple absorber tower to absorb CO2 from flue gas. Furthermore, MEA, DEA, and MDEA adsorbents were used with a temperature of 38 °C and their concentration varied from 10 to 15%. Circulation rates of 200–300 m3/h were used for each concentration and solvent. The findings deduced that MEA is a promising solvent compared to DEA and MDEA in terms of the highest CO2 captured; however, it is limited at the top outlet for clean flue gas, which contained 3.6295% of CO2 and less than half a percent of DEA and MDEA, but this can be addressed either by increasing the concentration to 15% or increasing the MEA circulation rate to 300 m3/h.

scholarly journals Membrane Processes for Direct Carbon Dioxide Capture From Air: Possibilities and Limitations

2021 ◽  
Vol 3 ◽  
Author(s):  
Christophe Castel ◽  
Roda Bounaceur ◽  
Eric Favre
Keyword(s):  
Carbon Capture ◽  
Power Plants ◽  
Large Scale ◽  
Energy Requirement ◽  
Production Capacity ◽  
Operating Conditions ◽  
Alkaline Solutions ◽  
Membrane Unit ◽  
Membrane Processes ◽  
The Impact

The direct capture of CO2 from air (DAC) has been shown a growing interest for the mitigation of greenhouse gases but remains controversial among the engineering community. The high dilution level of CO2 in air (0.04%) indeed increases the energy requirement and cost of the process compared to carbon capture from flue gases (with CO2 concentrations around 15% for coal power plants). Until now, solid sorbents (functionalized silica, ion exchange resins, metal–organic frameworks, etc.) have been proposed to achieve DAC, with a few large-scale demonstration units. Gas-liquid absorption in alkaline solutions is also explored. Besides adsorption and absorption, membrane processes are another key gas separation technology but have not been investigated for DAC yet. The objective of this study is to explore the separation performances of a membrane unit for CO2 capture from air through a generic engineering approach. The role of membrane material performances and the impact of the operating conditions of the process on energy requirement and module production capacity are investigated. Membranes are shown to require a high selectivity in order to achieve purity in no more than two stages. The specific energy requirement is globally higher than that of the adsorption and absorption processes, together with higher productivity levels. Guidelines on the possibilities and limitations of membranes for DAC are finally proposed.

scholarly journals Screening of native microalgae species for carbon fixation at the vicinity of Malaysian coal-fired power plant

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Liyana Yahya ◽  
Razif Harun ◽  
Luqman Chuah Abdullah
Keyword(s):  
Power Plant ◽  
Flue Gas ◽  
Carbon Capture ◽  
Power Plants ◽  
Carbon Fixation ◽  
Operating Conditions ◽  
Emission Mitigation ◽  
Fixation Rate ◽  
Carbon Emission Mitigation ◽  
Gas Exposure

AbstractGlobal warming has become a serious issue nowadays as the trend of CO2 emission is increasing by years. In Malaysia, the electricity and energy sector contributed a significant amount to the nation’s CO2 emission due to fossil fuel use. Many research works have been carried out to mitigate this issue, including carbon capture and utilization (CCUS) technology and biological carbon fixation by microalgae. This study makes a preliminary effort to screen native microalgae species in the Malaysian coal-fired power plant’s surrounding towards carbon fixation ability. Three dominant species, including Nannochloropsis sp., Tetraselmis sp., and Isochrysis sp. were identified and tested in the laboratory under ambient and pure CO2 condition to assess their growth and CO2 fixation ability. The results indicate Isochrysis sp. as the superior carbon fixer against other species. In continuation, the optimization study using Response Surface Methodology (RSM) was carried out to optimize the operating conditions of Isochrysis sp. using a customized lab-scale photobioreactor under simulated flue gas exposure. This species was further acclimatized and tested under actual flue gas generated by the power plant. Isochrysis sp. had shown its capability as a carbon fixer with CO2 fixation rate of 0.35 gCO2/L day under actual coal-fired flue gas exposure after cycles of acclimatization phase. This work is the first to demonstrate indigenous microalgae species' ability as a carbon fixer under Malaysian coal-fired flue gas exposure. Thus, the findings shall be useful in exploring the microalgae potential as a biological agent for carbon emission mitigation from power plants more sustainably.

Flue Gas Recirculation of the Alstom Sequential Gas Turbine Combustor Tested at High Pressure

2011 ◽  
Author(s):  
Felix Guethe ◽  
Dragan Stankovic ◽  
Franklin Genin ◽  
Khawar Syed ◽  
Dieter Winkler
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Flue Gas ◽  
Operating Conditions ◽  
Limiting Factors ◽  
Combustion System ◽  
Flue Gas Recirculation ◽  
Wide Range ◽  
Gas Recirculation ◽  
The Impact

Concerning the efforts in reducing the impact of fossil fuel combustion on climate change for power production utilizing gas turbine engines Flue Gas Recirculation (FGR) in combination with post combustion carbon capture and storage (CCS) is one promising approach. In this technique part of the flue gas is recirculated and introduced back into the compressor inlet reducing the flue gas flow (to the CCS) and increasing CO2 concentrations. Therefore FGR has a direct impact on the efficiency and size of the CO2 capture plant, with significant impact on the total cost. However, operating a GT under depleted O2 and increased CO2 conditions extends the range of normal combustor experience into a new regime. High pressure combustion tests were performed on a full scale single burner reheat combustor high-pressure test rig. The impact of FGR on NOx and CO emissions is analyzed and discussed in this paper. While NOx emissions are reduced by FGR, CO emissions increase due to decreasing O2 content although the SEV reheat combustor could be operated without problem over a wide range of operating conditions and FGR. A mechanism uncommon for GTs is identified whereby CO emissions increase at very high FGR ratios as stoichiometric conditions are approached. The feasibility to operate Alstom’s reheat engine (GT24/GT26) under FGR conditions up to high FGR ratios is demonstrated. FGR can be seen as continuation of the sequential combustion system which already uses a combustor operating in vitiated air conditions. Particularly promising is the increased flexibility of the sequential combustion system allowing to address the limiting factors for FGR operation (stability and CO emissions) through separated combustion chambers.

scholarly journals Case studies of clinical hemodialysis membranes: influences of membrane morphology and biocompatibility on uremic blood-membrane interactions and inflammatory biomarkers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Heloisa Westphalen ◽  
Shaghayegh Saadati ◽  
Ubong Eduok ◽  
Amira Abdelrasoul ◽  
Ahmed Shoker ◽  
...  
Keyword(s):  
Membrane Surface ◽  
Cascade Reactions ◽  
Operating Conditions ◽  
Inflammatory Biomarkers ◽  
Membrane Properties ◽  
Dialysis Session ◽  
Blood Samples ◽  
Membrane Materials ◽  
The Impact

Abstract End stage renal disease (ESRD) patients depend on hemodialysis (HD) as a life-sustaining treatment, but HD membrane properties play a critical role in blood activation during HD and can lead to severe patient outcomes. This study reports on a series of investigations on the common clinical HD membranes available in Canadian hospitals to explore the key reasons behind their susceptibility to blood activation and unstable cytokine. Clinical HD membranes composed of cellulose triacetate (CTA) and polyvinylpyrrolidone: polyarylethersulfone (PAES: PVP) were thoroughly characterized in terms of morphology and chemical composition. Membrane-surface interactions with uremic blood samples after HD treatment were probed using Fourier Transform Infra-Red (FTIR) and Raman spectroscopic techniques in order to understand changes in chemistry on membrane fibers. In addition, as part of this innovative study, we utilized Molecular Modeling Docking to examine the interactions of human blood proteins and membrane models to gain an in-depth understanding of functional group types responsible for perceived interactions. In-vitro adsorption of fibrinogen on different clinical HD membranes was compared at similar clinical operating conditions. Samples were collected from dialysis patients to ascertain the extent of inflammatory biomarkers released, before, during (30 and 90 min) and after dialysis (4 h). Collected blood samples were analyzed using Luminex assays for the inflammatory biomarkers of Serpin/Antithrombin-III, Properdin, C5a, 1L-1α, 1L-1β, TNF-α, IL6, and vWF. We have likewise incubated uremic blood in vitro with the two membrane materials to determine the impact that membrane materials pose in favor of activation away from the hydrodynamics influences. The results of our morphological, chemical, spectroscopic, and in vitro incubation analyses indicate that CTA membranes have a smoother surface and higher biocompatibility than PAES: PVP membranes, however, it has smaller pore size distribution, which results in poor clearance of a broad spectrum of uremic toxins. However, the rougher surface and greater hydrophilicity of PAES: PVP membranes increases red blood cell rupture at the membrane surface, which promotes protein adsorption and biochemical cascade reactions. Molecular docking studies indicate sulfone functional groups play an important role in the adsorption of proteins and receptors. PAES: PVP membranes result in slower but greater adsorption of fibrinogen, but are more likely to experience reversible and irreversible fouling as well as backfiltration. Our major finding is that a single dialysis session, even with a more biocompatible membrane such as CTA, increases the levels of complement and inflammation factors, but to a milder extent than dialysis with a PAES membrane.

scholarly journals Parametric Study of Various Thermodynamic Cycles for the Use of Unconventional Blends

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4656
Author(s):  
Odi Fawwaz Alrebei ◽  
Philip Bowen ◽  
Agustin Valera Medina
Keyword(s):  
Working Conditions ◽  
Parametric Study ◽  
Gas Turbines ◽  
Carbon Capture ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Simple Cycle ◽  
Working Fluid ◽  
Specific Work ◽  
Cycle Efficiency

This paper aims to conduct a parametric study for five gas turbine cycles (namely, simple, heat exchanged, free turbine and simple cycle, evaporative, and humidified) using a CO2-argon-steam-oxyfuel (CARSOXY) mixture as a working fluid to identify their optimal working conditions with respect to cycle efficiency and specific work output. The performance of the five cycles using CARSOXY is estimated for wet and dry compression, and a cycle is suggested for each range of working conditions. The results of this paper are based on MATLAB codes, which have been developed to conduct the cycle analysis for CARSOXY gas turbines, assuming a stoichiometric condition with an equivalence ratio of 1.0. Analyses are based on the higher heating value (HHV) of methane as fuel. This paper also identifies domains of operating conditions for each cycle, where the efficiency of CARSOXY cycles can be increased by up to 12% compared to air-driven cycles. The CARSOXY heat exchanged cycle has the highest efficiency among the other CARSOXY cycles in the compressor pressure ratio domain of 2–3 and 6–10, whereas, at 3–6, the humidified cycle has the highest efficiency. The evaporative cycle has intermediate efficiency values, while the simple cycle and the free turbine-simple cycle have the lowest efficiencies amongst the five cycles. Additionally, a 10% increase in the cycle efficiency can be theoretically achieved by using the newly suggested CARSOXY blend that has the molar fractions of 47% argon, 10% carbon dioxide, 10% H2O, and 33% oxyfuel at low compressor inlet temperatures, thus theoretically enabling the use of carbon capture technologies.

Modeling of Superheater Operation in a Steam Boiler

2014 ◽  
Author(s):  
Marcin Trojan ◽  
Dawid Taler ◽  
Jan Taler ◽  
Piotr Dzierwa
Keyword(s):  
Flue Gas ◽  
Tube Wall ◽  
Numerical Technique ◽  
Operating Conditions ◽  
Outlet Temperature ◽  
Steam Boiler ◽  
Steam Temperature ◽  
Additional Increase ◽  
Internal Surfaces ◽  
The Impact

A numerical method for modeling actual steam superheaters is presented. The finite volume method was used to determine flue gas, tube wall and steam temperature. The numerical technique presented in the paper can especially be used for modeling boiler superheaters with a complex tube arrangement when detail information on the tube wall temperature distribution is needed. The method of modeling the superheater can be used both in the design, performance as well as in upgrading the superheaters. If the steam temperature at the outlet of the superheater is too low or too high, the designed outlet temperature can be achieved by changing a flow arrangement of the superheater. For example, the impact of the change of the counter to parallel flow or to mixed flow can be easily assessed. The presented method of modeling is a useful tool in analyzing the impact of the internal scales or outer ash fouling on the superheater operating conditions. Both ash deposits at the external and scales at the internal surfaces of the tubes contribute to the reduction of the steam temperature at the outlet of the superheater. Furthermore, scale deposits on the inner surface of the tubes cause a significant temperature rise and may lead to the tube damage. The higher temperature of the flue gas over a part of parallel superheater tubes increases the steam temperature and decreases steam mass flow rate through the tubes with excessive heating. This results in an additional increase in the steam temperature at the outlet of the superheater.

Absorber modeling for NGCC carbon capture with aqueous piperazine

2016 ◽  
Vol 192 ◽  
pp. 459-477 ◽  
Author(s):  
Yue Zhang ◽  
Brice Freeman ◽  
Pingjiao Hao ◽  
Gary T. Rochelle
Keyword(s):  
Flue Gas ◽  
Water Availability ◽  
Carbon Capture ◽  
Power Plants ◽  
Cooling Water ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Wide Range ◽  
Natural Gas Combined Cycle ◽  
Dry Cooling

A hybrid system combining amine scrubbing with membrane technology for carbon capture from natural gas combined cycle (NGCC) power plants is proposed in this paper. In this process, the CO2 in the flue gas can be enriched from 4% to 18% by the membrane, and the amine scrubbing system will have lower capture costs. Aqueous piperazine (PZ) is chosen as the solvent. Different direct contact cooler (DCC) options, multiple absorber operating conditions, optimal intercooling designs, and different cooling options have been evaluated across a wide range of inlet CO2. Amine scrubbing without DCC is a superior design for NGCC carbon capture. Pump-around cooling at the bottom of the absorber can effectively manage the temperature of the hot flue gas, and still be effective for CO2 absorption. The absorber gas inlet must be designed to avoid excessive localized temperature and solvent evaporation. When the inlet CO2 increases from 4% to 18%, total absorber CAPEX decreases by 60%; another 10% of the total absorber CAPEX can be saved by eliminating the DCC. In-and-out intercooling works well for high CO2, while pump-around intercooling is more effective for low CO2. Dry cooling requires more packing and energy but appears to be technically and economically feasible if cooling water availability is limited.

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