Availability analysis of post-combustion carbon capture systems: Minimum work input

This paper describes the availability analysis of a generic, post-combustion carbon capture plant. The analysis first establishes the minimum work input required in an ideal plant with a flue gas inlet temperature equal to the sink temperature. The analysis shows that the ideal work input is surprisingly low and that, roughly equal amounts of work are required to first separate and then compress the CO2 contained in a typical flue gas stream. The analysis is then extended to include the effects of variable inlet temperature and extraction efficiency. This extended analysis shows that there is a considerable quantity of available energy in the flue gas of a normal power station. Indeed, in principle, carbon capture is theoretically possible without any external work input for fuels of low carbon/hydrogen ratio such as heavy fuel oil and natural gas. When burning coal, the minimum work input would be significantly reduced if the flue gases' availability were utilized. The final section of the paper compares the actual work input of a variety of carbon capture schemes found in the literature, with the minimum work input for an ideal process. This comparison shows that the techniques presently found in the literature have a low second-law efficiency.

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Seawater Scrubbing for the Removal of Sulfur Dioxide in a Steam Turbine Power Plant

ASME 2005 Power Conference ◽

10.1115/pwr2005-50051 ◽

2005 ◽

Cited By ~ 1

Author(s):

Akili D. Khawaji ◽

Jong-Mihn Wie

Keyword(s):

Power Plant ◽

Sulfur Dioxide ◽

Steam Turbine ◽

Flue Gas ◽

Operating Cost ◽

Cooling Water ◽

Cost Savings ◽

Fuel Oil ◽

So2 Emissions ◽

Heavy Fuel Oil

The most popular method of controlling sulfur dioxide (SO2) emissions in a steam turbine power plant is a flue gas desulfurization (FGD) process that uses lime/limestone scrubbing. Another relatively newer FGD technology is to use seawater as a scrubbing medium to absorb SO2 by utilizing the alkalinity present in seawater. This seawater scrubbing FGD process is viable and attractive when a sufficient quantity of seawater is available as a spent cooling water within reasonable proximity to the FGD scrubber. In this process the SO2 gas in the flue gas is absorbed by seawater in an absorber and subsequently oxidized to sulfate by additional seawater. The benefits of the seawater FGD process over the lime/limestone process and other processes are; 1) The process does not require reagents for scrubbing as only seawater and air are needed, thereby reducing the plant operating cost significantly, and 2) No solid waste and sludge are generated, eliminating waste disposal, resulting in substantial cost savings and increasing plant operating reliability. This paper reviews the thermodynamic aspects of the SO2 and seawater system, basic process principles and chemistry, major unit operations consisting of absorption, oxidation and neutralization, plant operation and performance, cost estimates for a typical seawater FGD plant, and pertinent environmental issues and impacts. In addition, the paper presents the major design features of a seawater FGD scrubber for the 130 MW oil fired steam turbine power plant that is under construction in Madinat Yanbu Al-Sinaiyah, Saudi Arabia. The scrubber with the power plant designed for burning heavy fuel oil containing 4% sulfur by weight, is designed to reduce the SO2 level in flue gas to 425 ng/J from 1,957 ng/J.

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A Pb/Zn Based Chemical Looping System for Hydrogen and Power Production With Carbon Capture

Volume 4: Cycle Innovations; Fans and Blowers; Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Oil and Gas Applications ◽

10.1115/gt2011-46602 ◽

2011 ◽

Author(s):

Niall R. McGlashan ◽

Peter R. N. Childs ◽

Andrew L. Heyes

Keyword(s):

Power System ◽

Flue Gas ◽

Power Output ◽

Carbon Capture ◽

Oxygen Carrier ◽

Fluid Phase ◽

Chemical Looping Combustion ◽

Inlet Temperature ◽

Chemical Looping ◽

Lower Efficiency

This paper describes an extension of a novel, carbon-burning, fluid phase chemical looping combustion system proposed previously. The system generates both power and H2 with ‘inherent’ carbon capture using chemical looping combustion (CLC) to perform the main energy release from the fuel. A mixed Pb and Zn based oxygen carrier is used, and due to the thermodynamics of the carbothermic reduction of PbO and ZnO respectively, the system generates a flue gas which consists of a mixture of CO2 and CO. By product H2 is generated from this flue gas using the water-gas shift reaction (WGSR). By varying the proportion of Pb to Zn circulating in the chemical loop, the ratio of CO2 to CO can be controlled, which in turn enables the ratio between the amount of H2 produced to the amount of power generated to be adjusted. By this means, the power output from the system can be ‘turned down’ in periods of low electricity demand without requiring plant shutdown. To facilitate the adjustment of the Pb/Zn ratio, use is made of the two metal’s mutual insolubility, as this means they form in to two liquid layers at the base of the reduction reactor. The amount of Pb and Zn rich liquid drawn from the two layers and subsequently circulated around the system is controlled thereby varying the Pb/Zn ratio. To drive the endothermic reduction of ZnO formed in the oxidiser, hot Zn vapour is ‘blown’ into the reducer where it condenses, releasing latent heat. The Zn vapour to produce this ‘blast’ of hot gas is generated in a flash vessel fed with hot liquid metal extracted from the oxidiser. A mass and energy balance has been conducted for a power system, operating on the Pb/Zn cycle. In the analysis, reactions are assumed to reach equilibrium and losses associated with turbomachinery are considered; however, pressure losses in equipment and pipework are assumed to be negligible. The analysis reveals that a power system with a second law efficiency of between 62% and 68% can be constructed with a peak turbine inlet temperature of only ca. 1850 K. The efficiency varies as the ratio between power and H2 production varies, with the lower efficiency occurring at the maximum power output condition.

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Bi-Objective Optimization of Vessel Speed and Route for Sustainable Coastal Shipping under the Regulations of Emission Control Areas

Sustainability ◽

10.3390/su11226281 ◽

2019 ◽

Vol 11 (22) ◽

pp. 6281 ◽

Cited By ~ 2

Author(s):

Yuzhe Zhao ◽

Yujun Fan ◽

Jingmiao Zhou ◽

Haibo Kuang

Keyword(s):

Carbon Emissions ◽

Emission Control ◽

Fuel Oil ◽

Low Carbon ◽

Heavy Fuel Oil ◽

Fuel Price ◽

Small Vessels ◽

Coastal Shipping ◽

Optimum Speed ◽

Vessel Speed

To comply with the regulations of emission control areas (ECAs), most operators have to switch to low-sulfur fuels inside the ECAs. Besides, a low-carbon objective is essential for long-term environmental protection; thus, is regarded as important as making profit. Therefore, the operators start making speed and route decisions under the two objectives of minimizing carbon emissions and maximizing profit. Drawing on existing methods, this paper formulates the profit and carbon emissions in sustainable coastal shipping, investigates the speed and route principles, and determines the best tradeoff between profit and carbon emissions. It is found that vessel speed should be set between emissions-optimum speed and profit-optimum speed, and the route must be selected in light of the speed decision. Next, the optimal choices of speed and route were examined under different scenarios and vessel types. The results show that the operation measures and objectives depend greatly on fuel price, vessel load, and vessel parameters. The operator should speed up the vessel if he/she wants to make more profit or if the scenario is favorable for profit making; e.g., low fuel price and high vessel load (LFHL). Large vessels should pursue more profit under LFHL conditions, without having to sail further outside the ECA. But this rule does not apply to small vessels. In addition, the operator should slow down the vessel inside the ECA and sail further, outside the ECA, with the growth in the price spread between marine gas oil (MGO) and heavy fuel oil (HFO), especially at a low HFO price. The research findings help operators to design operational measures that best suit the limit on sulfur content in fuel and the situation of the shipping market.

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Preliminary Calculations on Post Combustion Carbon Capture From Gas Turbines With Flue Gas Recycle

Volume 1B: Combustion, Fuels and Emissions ◽

10.1115/gt2013-94968 ◽

2013 ◽

Cited By ~ 2

Author(s):

Muhammad Akram ◽

Bhupendra Khandelwal ◽

Simon Blakey ◽

Christopher W. Wilson

Keyword(s):

Gas Turbine ◽

Flue Gas ◽

Gas Turbines ◽

Carbon Capture ◽

Hot Water ◽

Low Carbon ◽

Air Inlet ◽

Carbon Combustion ◽

Set Up ◽

The University

Carbon capture is getting increased attention recently due to the fact that it seems to be the only answer to decrease emissions. Gas turbines exhaust have 3–5 % concentration of CO2 which is very low to be captured by an amine carbon capture plant effectively. The amine based plants are most effective at around 10 – 15% CO2 in the flue gas. In order to increase the concentration of CO2 in the exhaust of the gas turbine, part of the exhaust gas needs to be recycled back to the air inlet. On reaching the concentration of CO2 around 10% it can be fed to the amine capture plant for effective carbon capture. A 100 kWe (plus 150 kW hot water) CHP gas turbine Turbec T100 is installed at the Low Carbon Combustion Centre of the University of Sheffield. The turbine set up will be modified to make it CO2 capture ready. The exhaust gases obtained will be piped to amine capture plant for testing capture efficiency. Preliminary calculations have been done and presented in this paper. The thermodynamic properties of CO2 are different from nitrogen and will have an effect on compressor, combustor and turbine performance. Preliminary calculations of recycle ratios and other performance based parameters have been presented in this paper. This paper also covers the aspects of turbine set up machinery which needs to be modified and what kind of modifications may be needed.

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A Comparison of Alternative Fuels for Shipping in Terms of Lifecycle Energy and Cost

Energies ◽

10.3390/en14248502 ◽

2021 ◽

Vol 14 (24) ◽

pp. 8502

Author(s):

Li Chin Law ◽

Beatrice Foscoli ◽

Epaminondas Mastorakos ◽

Stephen Evans

Keyword(s):

Natural Gas ◽

Carbon Capture ◽

Alternative Fuels ◽

Fossil Fuels ◽

Ghg Emissions ◽

Fuel Oil ◽

Heavy Fuel Oil ◽

Long Distance ◽

Reference Case ◽

Marine Fuel

Decarbonization of the shipping sector is inevitable and can be made by transitioning into low- or zero-carbon marine fuels. This paper reviews 22 potential pathways, including conventional Heavy Fuel Oil (HFO) marine fuel as a reference case, “blue” alternative fuel produced from natural gas, and “green” fuels produced from biomass and solar energy. Carbon capture technology (CCS) is installed for fossil fuels (HFO and liquefied natural gas (LNG)). The pathways are compared in terms of quantifiable parameters including (i) fuel mass, (ii) fuel volume, (iii) life cycle (Well-To-Wake—WTW) energy intensity, (iv) WTW cost, (v) WTW greenhouse gas (GHG) emission, and (vi) non-GHG emissions, estimated from the literature and ASPEN HYSYS modelling. From an energy perspective, renewable electricity with battery technology is the most efficient route, albeit still impractical for long-distance shipping due to the low energy density of today’s batteries. The next best is fossil fuels with CCS (assuming 90% removal efficiency), which also happens to be the lowest cost solution, although the long-term storage and utilization of CO2 are still unresolved. Biofuels offer a good compromise in terms of cost, availability, and technology readiness level (TRL); however, the non-GHG emissions are not eliminated. Hydrogen and ammonia are among the worst in terms of overall energy and cost needed and may also need NOx clean-up measures. Methanol from LNG needs CCS for decarbonization, while methanol from biomass does not, and also seems to be a good candidate in terms of energy, financial cost, and TRL. The present analysis consistently compares the various options and is useful for stakeholders involved in shipping decarbonization.

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Swirling Flame Combustion of Heavy Fuel Oil: Effect of Fuel Sulfur Content

Journal of Energy Resources Technology ◽

10.1115/1.4048942 ◽

2020 ◽

Vol 143 (8) ◽

Author(s):

Xinyan Pei ◽

Abdul Gani Abdul Jameel ◽

Chaoqin Chen ◽

Ibrahim A. AlGhamdi ◽

Kamal AlAhmadi ◽

...

Keyword(s):

Temperature Distribution ◽

Sulfur Content ◽

Flue Gas ◽

Flame Temperature ◽

Fuel Oil ◽

Gaseous Emissions ◽

So2 Emissions ◽

Heavy Fuel Oil ◽

Ultra Low Sulfur Diesel ◽

Swirling Flame

Abstract In the present work, an experimental investigation on the effect of sulfur content in heavy fuel oil (HFO) on the gaseous emissions under swirling flame conditions was carried out. The sulfur content in HFO was varied by blending with ultra-low sulfur diesel and four fuel samples containing 3.15, 2.80, 1.97, and 0.52% sulfur (by mass) were prepared. Pure asphaltenes were added to the blends to ensure that the asphaltene content in the fuel remained the same. The fuels were then fired in a high-swirl stabilized, turbulent spray flame. The combustion performance of the fuels was evaluated by measuring flame temperature distribution, gaseous emissions (SOx, NOx, CO, CO2, and flue gas pH), and particulate matter (PM) emissions (morphology, composition, and pH). The results showed a significant reduction in the SO2 emissions and acidity of the flue gas when the sulfur content in the fuel was reduced, as expected. The reduction was more than would be expected based on sulfur content, however. For example, the flue gas SO2 concentration reduced from 620 ppm to 48 ppm when the sulfur content in the fuel was reduced from 3.15 to 0.52% (by mass). Sulfur balance calculations indicate that nearly 97.5% of the sulfur in the fuel translates into gaseous emissions and the remaining 2.5% appears in PM emissions. Ninety-five percent of the gaseous sulfur emissions are SO2, whereas the rest appears as SO3. Varying the sulfur content in the fuel did not have a major impact on the flame temperature distribution or NOx emissions. The morphologies and the size distribution of the PM also did not change significantly with the sulfur content as the asphaltenes content of the fuels remained the same.

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Decarbonizing Maritime Transport: The Importance of Engine Technology and Regulations for LNG to Serve as a Transition Fuel

Sustainability ◽

10.3390/su12218793 ◽

2020 ◽

Vol 12 (21) ◽

pp. 8793 ◽

Cited By ~ 2

Author(s):

Elizabeth Lindstad ◽

Gunnar S. Eskeland ◽

Agathe Rialland ◽

Anders Valland

Keyword(s):

Fossil Fuels ◽

Combustion Engine ◽

Ghg Emissions ◽

Fuel Oil ◽

Maritime Transport ◽

Low Carbon ◽

Heavy Fuel Oil ◽

Gas Emissions ◽

Global Warming Impact ◽

Ghg Reduction

Current Greenhous gas emissions (GHG) from maritime transport represent around 3% of global anthropogenic GHG emissions and will have to be cut in half by 2050 to meet Paris agreement goals. Liquefied natural gas (LNG) is by many seen as a potential transition fuel for decarbonizing shipping. Its favorable hydrogen to carbon ratio compared to diesel (marine gas oil, MGO) or bunker fuel (heavy fuel oil, HFO) translates directly into lower carbon emissions per kilowatt produced. However, these gains may be nullified once one includes the higher Well-to-tank emissions (WTT) of the LNG supply chain and the vessel’s un-combusted methane slip (CH4) from its combustion engine. Previous studies have tended to focus either on greenhouse gas emissions from LNG in a Well-to-wake (WTW) perspective, or on alternative engine technologies and their impact on the vessel’s Tank-to-wake emissions (TTW). This study investigates under what conditions LNG can serve as a transition fuel in the decarbonization of maritime transport, while ensuring the lowest possible additional global warming impact. Transition refers to the process of moving away from fossil fuels towards new and low carbon fuels and engine technologies. Our results show: First, the importance of applying appropriate engine technologies to maximize GHG reductions; Second, that applying best engine technologies is not economically profitable; Third, how regulations could be amended to reward best engine technologies. Importantly, while the GHG reduction of LNG even with best engine technology (dual fuel diesel engine) are limited, ships with these engines can with economically modest modification switch to ammonia produced with renewable energy when it becomes available in sufficient amounts.

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Semi-Closed CCGT Cycle With High Temperature Reactants Combustion

Volume 1 ◽

10.1115/esda2004-58472 ◽

2004 ◽

Author(s):

S. M. Camporeale ◽

F. Casalini ◽

A. Saponaro

Keyword(s):

High Temperature ◽

Large Range ◽

Soot Formation ◽

Fuel Oil ◽

Stable Operation ◽

Inlet Temperature ◽

Stable Form ◽

Nox Emissions ◽

Heavy Fuel Oil ◽

Mild Combustion

In the last years many research studies have been focused on the features of MILD combustion that is a stable form of combustion, obtained with high temperature reactants and high exhaust gas recirculation and characterized by low flame temperature and, consequently, low Nox emissions. This form of combustion is also characterized by low light emissions (for this reason it is also called “flameless” combustion) and a large range of stable operation. MILD combustion has been already applied in industrial furnaces where ceramic regenerators provide to raise the temperature of the entering diluted air, the main advantages being high efficiency and low emissions. The introduction of MILD combustion in power plants would allow for increasing the temperature of the entering reactants beyond the self-ignition temperature without increasing the NOx emission. The main goals of this technique are low combustion exergy losses, large range of stable combustion, and low NOx emissions. Some experiments have shown that the flameless conditions can be obtained using diluted reactants, even using heavy fuel oil. Good results in terms of NOx emissions and soot formation have been obtained for heavy oil combustion in a 10% oxygen concentration of reactants and combustion chamber inlet temperature of about 900K. In order to meet these conditions, a semiclosed CCGT cycle with high recirculation ratio, suitable for the use of heavy fuel oil, is proposed here, assuming state-of-the-art technologies for gas turbine and steam plant and steam cooling of the turbine blades. The thermodynamic analysis shows that the overall plant efficiency of the new scheme is close to 60% that is about the efficiency that can be obtained in modern CCGT power plant fuelling natural gas.

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