Carbon Capture Unit Research Articles

Ensemble process for producing high-purity H2 via simultaneous in situ H2 extraction and CO2 capture

To produce fuel-cell-grade hydrogen (H 2 ) via fossil fuel reforming processes, an efficient H 2 purification method with a carbon capture unit is necessary. In this study, a sorption-enhanced water-gas shift membrane reactor (SE-WGS-MR) system combining a state-of-the-art MgO-based catalyst, carbon dioxide sorbent, and Pd/Ta membrane is developed to simultaneously capture carbon dioxide and purify H 2 . With the optimal sorption-enhanced configuration (SE-WGS), the carbon monoxide conversion is significantly enhanced to 86.6%, compared with 68.5% using the commercial catalyst only. Coupling of the Pd/Ta membrane with the WGS catalyst (WGS-MR) enable over 95% H 2 recovery, with the production of high-purity H 2 . Eventually, the ensemble of the three processes (SE-WGS-MR) afford 99.99% of carbon monoxide conversion and the extraction of high-purity H 2 with 99.5% recovery. This study demonstrates the potential of the single process integrating the catalytic reaction, adsorptive separation, and membrane purification for the production of H 2 with ultra-high purity and recovery. • Integration of WGS catalyst and CO 2 sorbent with a Pd/Ta membrane is examined • Coupling of the Pd/Ta membrane with the WGS catalyst enables over 95% H 2 recovery • Simultaneous CO 2 capture and H 2 purification shifts the CO conversion to 99.99% • The ensemble of the processes extracts ultra-pure H 2 with over 99.5% recovery Jin et al. propose an effective ensemble process for producing pure H 2 via simultaneous in situ H 2 extraction and CO 2 capture. Integration of MgO-based catalyst and CO 2 sorbent with a Pd/Ta composite membrane shifts the CO conversion to 99.99%, enabling the extraction of pure H 2 with over 99.5% recovery.

Potential enhancement in atmospheric new particle formation by amine-assisted nitric acid condensation at room temperature

Atmospheric aerosol plays a critical role in global climate and public health. Recent laboratory experiments showed that new particle formation is significantly enhanced by rapid condensation of nitric acid and ammonia at low temperatures. Amines are derivatives of ammonia with a significant presence in the atmosphere. For example, the wide implementation of amine-based Post-Combustion Carbon Capture (PCCC) units may significantly increase the ambient alkanolamine and polyamine levels. Using thermodynamic simulations, the condensation of alkylamines, alkanolamines and polyamines with nitric acid at various temperatures was systematically evaluated. Alkylamines will condense with nitric acid at temperatures comparable to that of ammonia. However, with additional hydrogen bonding groups, alkanolamines and polyamines may condense with nitric acid at room temperature, suggesting a new potential pathway to remove these amines from the atmosphere. Our results suggest the potentially critical role of amines in the atmospheric new particle formation via condensation with nitric acid to rapidly grow freshly nucleated clusters over their critical size at a higher temperature than ammonia. The condensed amines and nitric acid can also facilitate water uptake by aerosol particles at low relative humidity, which may alter their subsequent atmospheric transformations.

Negative Emission Power Plants: Thermodynamic Modeling and Evaluation of a Biomass-Based Integrated Gasification Solid Oxide Fuel Cell/Gas Turbine System for Power, Heat, and Biochar Co-Production—Part 1

This article is the first of a two-part series presenting the thermodynamic evaluation and techno-economics of developing negative-emission power plants. The aim of this research is to evaluate the potential of biochar co-production in negative-emission power plants based on biomass-fed integrated gasification solid oxide fuel cell systems with carbon capture and storage (BIGFC/CCS) units. The influence of two gasification agents, namely, air and steam-oxygen, on the proposed system is investigated. In Part I, we present the thermodynamic models. A sensitivity analysis is carried out to investigate the system response to stepwise increase in biochar co-production (up to 10% by weight). Providing a secondary oxy-combustor in the steam-oxygen gasification case has been shown to be a solution to meet the heat requirements of the allothermal gasification process. A comprehensive exergy analysis indicated significant efficiency improvement for the steam-oxygen gasification case. The results show that the biomass steam-oxygen gasification yields the higher electrical exergy efficiency (48.3%) and combined heat and power (CHP) exergy efficiency (54.6%) for the similar rates of biochar co-production. The specific power output per unit of CO2 stored is 2.65 MW/(kg/s) and 3.58 MW/(kg/s) for the air and steam-oxygen gasification cases, respectively, when the biochar is co-produced at 10% by weight for the given biomass flow of 20 kg/s. Moreover, the total CO2 stored due to the proposed system is calculated as 133.9 t/h, and it is estimated to remove 1.17 Mt of CO2 from the atmosphere annually (when the biochar-based carbon storage is also considered). The models are used for the techno-economic analysis presented in Part II of the series.

Technical and environmental performances of alternative treatments for challenging plastics waste

The recovery of resources from streams of mixed plastics waste is a technological and economic challenge since they contain various (and generally non-compatible) polymers, different (and often hazardous) additives, as well as multilayer structures and fiber-reinforced composites. Only a too limited part of these plastics - such as those coming from waste of electric and electronic equipment (WEEE), end-of-life vehicles (ELV) and construction and demolition waste (C&DW) - can be treated by mechanical techniques in the conventional recycling facilities, and a still smaller part is reintroduced into the market. Some innovative treatments have been recently proposed and appear suitable for these challenging waste streams. The paper describes technical characteristics of some of them, and compares their environmental performances with those of currently adopted management options. An environmental life cycle assessment was developed by taking into account the substitutability factor of obtained products and technological readiness level of the analyzed resource recovery processes. The focus is on new treatments of dissolution/precipitation, supercritical fluid extraction, catalytic pyrolysis, and waste-to-energy (WtE) equipped with carbon capture and storage unit (CCS). The results highlight the promising performances of some of these new options, quantify their potential environmental advantages, and suggest to take them into account in the definition of sustainable management schemes for the examined challenging plastics wastes. In particular, physical recycling by dissolution/precipitation process applied to one tonne of WEEE plastics, not treatable by mechanical recycling, can save up to about 2 tCO2,eq. with respect to landfill disposal and WtE with CCS, and more than 3 tCO2,eq. with respect to WtE without CCS. The performances of WtE with CCS appear of interest, particularly for WEEE and ELV mixed plastics, allowing to save up to 0.5 tCO2,eq. and 1.7 tCO2,eq., with respect to pyrolysis and WtE without CCS, respectively.

Sensitivity Analysis and Cost Estimation of a CO2 Capture Plant in Aspen HYSYS

A standard CO2 capture process is implemented in Aspen HYSYS, simulated, and evaluated based on available data from Fortum’s waste burning facility at Klemetsrud in Norway. Since amine-based CO2 removal has high costs, the main aim is cost-optimizing. A simplified carbon-capture unit with a 20-m absorber packing height, 90% CO2 removal efficiency, and a minimum approach temperature for the lean/rich amine heat exchanger (ΔTmin) of 10 °C was considered the base case simulation model. A sensitivity analysis was performed to optimize these parameters. For the base case study, CO2 captured cost was calculated as 37.5 EUR/t. When the sensitivity analysis changes the size, the Power Law method adjusts the equipment cost. A comparison of the Enhanced Detailed Factor (EDF) and the Power Law approach was performed for all simulations to evaluate the uncertainties in the findings from the Power Law method. The optimums calculated for ΔTmin and CO2 capture rate were 15 °C and 87% for both methods, with CO2 removal costs of 37 EUR/t CO2 and 36.7 EUR/t CO2, respectively. With 19 m of packing height to absorber, the minimum CO2 capture cost was calculated as 37.3 EUR/t and 37.1 EUR/t for the EDF and Power Law methods, respectively. Since there was a difference between the Power Law method and the EDF method, a size factor exponent derivation was performed. The derivation resulted in the following exponents: for the lean heat exchanger 0.74, for the lean/rich heat exchanger 1.03, for the condenser 0.68, for the reboiler 0.92, for the pump 0.88, and for the fan 0.23.

Atmospheric Dispersion of Gaseous Amine Emitted from Absorption-Based Carbon Capture Plants in Saskatchewan, Canada

Carbon capture and storage (CCS) is a key strategy to reduce carbon dioxide (CO2) emissions from industrial point sources. Gas absorption into aqueous amine solutions is an immediate technology for carbon capture that has been tested in many demonstration plants. One concern of using the amine-based carbon capture process is the environmental impacts and health risk caused by emissions of gaseous amines from the process to the atmosphere. This work applied the knowledge of air dispersion modelling to map out the atmospheric dispersion and resulting ground surface level concentration of gaseous amine, namely Monoethanolamine (MEA), from a coal-fired power plant (with a carbon capture unit) and in surrounding areas, in case of an accidental leaking of amine from the CCS system to the atmosphere. The chosen study area was centered on a coal-fired power plant in the province of Saskatchewan, Canada. The Environmental Protection (EPA) approved air pollution model (CALPUFF), together with meteorological and geophysical data were used for gaseous amine dispersion simulation. The results were presented, and the ground amine concentrations were found to vary with wind patterns (wind direction and wind speed). The maximum ground surface amine concentrations standard is 15.2 µg/m3. However, the results showed that when using the water wash unit, the MEA concentrations were well below the standard level, compared to those without the water wash unit. It is essential for CO2 capture plants located in highly populated areas to be equipped with water wash units.

Numerical Analysis of VPSA Technology Retrofitted to Steam Reforming Hydrogen Plants to Capture CO2 and Produce Blue H2

The increasing demand for energy and commodities has led to escalating greenhouse gas emissions, the chief of which is represented by carbon dioxide (CO2). Blue hydrogen (H2), a low-carbon hydrogen produced from natural gas with carbon capture technologies applied, has been suggested as a possible alternative to fossil fuels in processes with hard-to-abate emission sources, including refining, chemical, petrochemical and transport sectors. Due to the recent international directives aimed to combat climate change, even existing hydrogen plants should be retrofitted with carbon capture units. To optimize the process economics of such retrofit, it has been proposed to remove CO2 from the pressure swing adsorption (PSA) tail gas to exploit the relatively high CO2 concentration. This study aimed to design and numerically investigate a vacuum pressure swing adsorption (VPSA) process capable of capturing CO2 from the PSA tail gas of an industrial steam methane reforming (SMR)-based hydrogen plant using NaX zeolite adsorbent. The effect of operating conditions, such as purge-to-feed ratio and desorption pressure, were evaluated in relation to CO2 purity, CO2 recovery, bed productivity and specific energy consumption. We found that conventional cycle configurations, namely a 2-bed, 4-step Skarstrom cycle and a 2-bed, 6-step modified Skarstrom cycle with pressure equalization, were able to concentrate CO2 to a purity greater than 95% with a CO2 recovery of around 77% and 90%, respectively. Therefore, the latter configuration could serve as an efficient process to decarbonize existing hydrogen plants and produce blue H2.

Mitigation of NOx and CO2 from diesel engine with EGR and carbon capture unit

Mitigation of NOx and CO2 from diesel engine with EGR and carbon capture unit

Life cycle assessment of amine-based versus ammonia-based post combustion CO2 capture in coal-fired power plants

Considering two sets of subcritical and supercritical 500 MW coal fired power plants with and without CO2 capture unit, a comparative, cradle-to-gate life cycle assessment was performed to evaluate the environmental impact of CO2 capture through amine-based and ammonia-based absorption from the flue gasses. The aqueous solutions of monoethanolamine (MEA) was considered as the amine solvent. The effects of MEA concentration of 20, 30, and 40 wt% and CO2 capture efficiency on the environmental impact of different categories were investigated. The methods of IPCC 2013 GWP 100a, AWARE V1.02, ReCiPe 2016 Midpoint (H) V1.03, and TRACI 2.1 V1.05, were considered for this LCA. In terms of global warming, adding a CO2 capture unit presented significant benefits for the environment. However, for other impact categories such as water footprint, ozone depletion, ionizing radiation, marine eutrophication, smog and fossil fuel depletion the plants with CO2 capture unit showed higher impact compared to the plants without a CO2 capture unit. In terms of carbon and water footprints MEA-based CO2 capture unit presents better performance compare to the ammonia-based.

Poison Effects on Alkaline CO2 Electrolyzer Using Sustainion® Membrane

Sustainion® anion exchange membranes have shown superior performance among competition in water and carbon dioxide (CO2) electrolysis. For example, CO2 electrolyzer using Sustainion membrane demonstrated a current density of 600mA/cm2 and a lifetime of over 4000hrs with over 95% CO Faradaic efficiency [1]. The results are achieved with pure CO2. In industrial applications, CO2 feedstocks could be low to mid concentrations CO2 streams from a carbon capture unit or high concentration CO2 streams from biorefinery. CO2 feedstocks from industry often contains impurities such as O2, NOx, SOx, VOCs (volatile organic compounds), and VSCs (volatile sulfur compounds), etc. Some of these impurities could poison the catalysts and degrade the membranes, leading to the early failure of the electrolyzer. In this work we investigated the effects of CO2 concentration and several compounds on the performance of Dioxide Materials electrolyzers for the conversion of CO2 into CO.The results show that most VOCs have no effect on performance. However, acetaldehyde crosses through the membrane and leads to anode degradtation. H2S starts to have significant effect at the 15ppm level. We will present these results and discuss the potential mitigation and/or regeneration strategies. Liu, Z.; Yang, H.; Kutz, R.; Masel, R. I., CO2 Electrolysis to CO and O2 at High Selectivity, Stability and Efficiency Using Sustainion Membranes. Journal of The Electrochemical Society 2018, 165, (15), J3371-J3377.

Research on optimal dispatch method of virtual power plant considering various energy complementary and energy low carbonization

Virtual power plant (VPP), as a new generation of intelligent control technology integrating multi-link resources of “source-load-storage”, can break regional restrictions and realize energy interconnection and sharing in wide area. In order to utilize multi-energy synthetically and efficiently and promote low carbon energy development, the natural gas production and consumption system is built and reasonably regulated, which is composed of carbon capture unit, power to gas (P2G), manure treatment system (MTS), combined heat and power (CHP) unit and gas fired boiler (GB). P2G uses the captured CO2 as raw material to meet the natural gas demand of CHP and GB together with MTS. In order to deal with the difference of “source load” resources of VPP in the same region and solve the problem of power real-time balance caused by the fluctuation of distributed renewable energy (DRE), the multi-system and multi-unit coordinated operation framework is constructed. Based on the shiftable load characteristics of carbon capture power consumption and flue gas treatment power consumption, the fluctuation of renewable energy output power can be stabilized, and the flexible utilization of wind turbine and photovoltaic can be indirectly realized. Internal energy mutual benefit between VPP regions is priced independently to encourage multiple regions of VPP to participate in the joint scheduling. Aiming at maximization of the operation benefit, a VPP optimal scheduling model of energy sharing and interaction among multiple regions is established, and a coordinated optimal scheduling strategy of distributed energy multiple regions in VPP is proposed. In view of the characteristics of the above model, such as high-dimensional, nonlinear and difficult to solve, the populational variation basis vector is introduced into the compound differential evolution algorithm to solve the model. The simulation results show that the proposed model and method can achieve the coordinated and optimal dispatch of power and heat energy between regions in multiple regions VPP, improve the capacity of renewable energy power utilization, reduce the power curtailment cost of WT and PV by 82%, reduce the carbon emission of VPP, increase the carbon trading revenue by 75%, and increase the operation income of VPP by 9%.

Modeling a biogas upgrading PSA unit with a sustainable activated carbon derived from pine sawdust. Sensitivity analysis on the adsorption of CO2 and CH4 mixtures

Pressure Swing Adsorption (PSA) is one of the implemented technologies for removing carbon dioxide in biogas streams. Different adsorbents, mostly zeolite-based, and process configurations have been patented and commercially demonstrated. In this study, we have developed a numerical model to successfully describe the dynamic performance of biomass-derived activated carbon in biogas purification. It is the first step in designing a biomass-based carbon capture unit within the bioenergy and circular economy context.Microporous activated carbon pellets prepared from pine sawdust by physical activation with CO2 was the adsorbent material choice. The model was built with the fittings of single-component adsorption isotherms of CO2 and CH4 at different temperatures to the Langmuir-Freundlich model and the Ideal Adsorbed Solution Theory (IAST) to account for multicomponent adsorption. The kinetics of mass transfer in the solid phase was described by the Linear Driving Force model (LDF).The dynamic simulations were performed with the aid of the commercial software Aspen Adsorption and experimental data previously obtained in the laboratory used for the model validation [1]. The model was applied to address the separation performance of a biogas upgrading biomass-based PSA process by running a parametric study to determine the influence of key performance parameters. The sensitivity analysis concluded that a single stage 4-step PSA can produce methane with a purity above 95% and a recovery of around 60% in a configuration with P/F ratios (quotients of molar flows of CH4 in the purge and the feed streams) between 0.67 and 1 for an adsorption pressure of 3 bar.

Energy, exergy, exergoeconomic and exergoenvironmental analysis and optimization of quadruple combined solar, biogas, SRC and ORC cycles with methane system

The present work deals with a novel configuration of four cycles such as steam gas cycles and an organic Rankine cycle and a biogas Brayton cycle and a solar Brayton cycle are introduced for recovering energy from hot exhaust gas and its simulation and optimization are discussed. Also, a carbon-amine adsorption system has been utilized for separating and storing carbon dioxide from hot exhaust gases and convert it to methane. For this new system, exergy, economical exergy, energy, economic and environmental exergy evaluations have been performed. To analyze the different parts, their thermodynamic and economic models, EES and MATLAB software have been used to optimize the exergy-economic cycle in order to reduce costs and increase exergy. In this research, genetic algorithm has been used for optimization. At the optimal point, the values of exergy efficiency are equal to 61.7% and the cost of electricity generation is 6.36 cent per kilowatt hour. The results show that adding Rankine cycles to the gas cycles increments the exergy and energy efficiency to 73.7 and 71.8, respectively. Nevertheless, integrating the carbon capture unit with this system reduced the exergy and energy efficiency to 51.9% and 50.5%, respectively. Based on the economic results for the presented system, it is indicated that the simple return on investment and return on investment are both 1.5 years. In addition, internal rate and net present value of return were 0.68 and 3.13*09 $ respectively. This system can generate 327,160 kW of electricity in addition, the carbon capture system unit can prevent and convert 627,000 tons of carbon dioxide into methane fuel annually.

Experimental investigation on performance of absorbents for carbon dioxide capture from diesel engine exhaust

AbstractThe postcombustion CO2 capture technology (PCC) is the topic of surplus study because it offers ease of implementation in the existing systems. To the best of the authors' knowledge, this technique has never been used for the automobile sector which has a major contribution toward anthropogenic CO2. In this article, experimental investigation has been carried out on the chemical solvents to determine the efficacy of capturing CO2 from multi‐pollutant diesel engine exhaust. The captured CO2 is measured in terms of percentage by volume of the total exhaust gas from three primary amines solvents, that is, monoethanolamine (MEA), N,N‐dimethylethanolamine (DMEA), and ammonia at seven brake power values, and their capture efficiencies are compared. A proposed design for the implementation of carbon capture unit in the existing heavy‐duty diesel engine has also been presented with theoretical calculation on the weight of the storage tank. Energy balance analyses have been performed to determine the energy needed to regenerate the solvents. It is found that the regeneration energy required for solvents MEA, DMEA, and ammonia is 2.2, 0.7, and 1.1 kWh, respectively which is quite lower than the total energy available with exhaust gas. Experimental results show that capture efficiency at ambient conditions with absorbents MEA, DMEA, and chilled ammonia is 90.95, 57.66, and 80.08, respectively. It reveals that the PCC method can be implemented in an existing diesel engine with MEA as an efficient and safe solvent.

Integration between biomass gasification and high-temperature electrolysis for synthetic methane production

The energy system analysis of an integrated process producing synthetic natural gas (SNG) from woody biomass has been carried out. Two different process configurations have been proposed and modeled, considering the integration between biomass gasification, solid oxide electrolysis (SOEC) and catalytic reactors for methane synthesis. The two investigated process configurations differ in the size of the SOEC unit. In the first configuration, the electrolysis unit is sized to increase H2 content in the produced syngas to satisfy the methanation reaction stoichiometric requirement. In the second configuration, electrolysis provides to the gasifier the requested amount of oxygen. For this second configuration, an additional section composed of a water gas shift (WGS) reactor and a carbon capture and sequestration (CCS) unit is required to adjust the reacting gas composition and thus to ensure the proper stoichiometry for the methanation process. The two different configurations have been compared at the same gasification condition. The gasifier has been modeled and studied to choose the gasification parameters' appropriate values, as equivalence ratio and steam-to-biomass ratio, and their impact on gasification outlet temperature and syngas composition. The whole process has been analyzed from a thermodynamic standpoint. After a thermal integration between the streams of the plant, energy efficiency has been calculated for both configurations: the first one (SOEC sized on hydrogen requirement) presented an efficiency of 71.7 %, while the second one (SOEC sized on oxygen requirement) showed an efficiency of 66.8 %.

Understanding the Potential of Bio-Carbon Capture and Storage from Biomass Power Plant in Indonesia

Indonesia is currently experiencing a significant increase in population, industrialization and energy demand. As the energy demand increases, so does the production of climate-altering CO2 emission. Biomass power plants have emerged as a low carbon power generation alternative, utilizing agricultural and industrial waste. Biomass power plants have the potential of being a carbon-negative power generation technology in the near future by integrating carbon and capture storage (bio-CCS). The objective of this paper is to analyze and map potential CO2 emission in the processes of biomass power plants from gasification and firing or co-firing technology, then recommend suitable carbon capture technology based on the biomass power plant characteristics in Indonesia. The CO2 emission to be captured in the gasification process is 11-15% of the producer gas, while in co-firing it is 7-24% of the flue gas stream. Using biomass instead of coal in power plants reduces the electric efficiency and increases the plant’s in-house emission, but when analyzed in a wider boundary system it is apparent that the net GWP and CO2 emission of biomass power plants are way smaller than coal power plant, moreover when equipped with carbon capture unit. Biomass power plant that uses firing technology can reduce CO2 emission by 148% compared to typical coal power plant. Installing carbon capture unit in biomass firing power plants can further reduce the specific CO2 emission by 262%. If carbon capture technology is implemented to all existing biomass power plants in Indonesia, it could reduce the greenhouse gas emission up to 2.2 million tonnes CO2 equivalent annually. It is found that there are 3 significant designs for gasification technology: NREL design, Rhodes & Keith design and IGBCC+DeCO2 design. The first two designs are not suitable to be retrofitted into existing biomass power plants in Indonesia since they are based on a specific BCL/FERCO gasifier. While IGBCC+DeCO2 design still needs further study regarding its feasibility. While for firing, the most promising technology to be applied in the near future is solvent-based absorption because it is already on commercial scale for coal-based power plants and can be implemented for other source, e.g. biomass power plant. Bio-CCS in existing biomass power plant with firing technology is likely to be implemented in the near future compared to the gasification, because it applies the post combustion capture as an “end-of-pipe” technology which is generally seen as a more viable option to be retrofitted to existing power plants, resulting in potentially less expensive transition.

Design and thermodynamic analysis of a novel methanol, hydrogen, and power trigeneration system based on renewable energy and flue gas carbon dioxide

In this paper, a new trigeneration system is proposed to decrease atmospheric carbon dioxide emission and produce methanol, hydrogen, and power. The system is composed of an organic Rankine cycle, a direct methanol fuel cell, a carbon capture unit, a proton exchange membrane electrolyzer, and a methanol synthesis unit. A flue gas stream with a defined composition, solar energy, and the atmospheric air are the system's inlets. In the design step, special attention is paid to heat and mass integration between different components so that its waste can be lowered as much as possible. Then, mass balance law, energy conservation principle, exergy relations, and auxiliary equations are applied for each subsystem to investigate the system's thermodynamic performance. Also, the effect of changing operating parameters on the performance of each subsystem is studied. The obtained results show that the proposed system has the energy and exergy efficiencies of 66.84% and 55.10%, respectively. Furthermore, 94% of the total exergy destruction rate belongs to the water electrolyzer, while the contribution of the organic Rankine cycle is negligible. The performance of the methanol synthesis reactor depends strongly on its inlet temperature. Maximum equilibrium methanol concentration and carbon dioxide conversion are achieved at the inlet temperature of 210 °C. The parametric studies reveal that there is an optimum fuel cell current density in which its produced power density is maximized.

Solar Integrated Unit to Reduce Power and Cooling Penalty of a Natural Gas Combined Cycle Plant integrated with a Carbon Capture System

Integrating solar assisted plant with a carbon capture unit to provide the required reboiler heat duty has been recently investigated extensively to reduce the negative impact of carbon capture unit on plant performance. However, using solar assisted plant to provide the required energy in the reboiler of the stripper leads to increase plant’s condenser duty unfavorably. In the present study, two novel configurations have been proposed for a concentrated solar assisted power plant to generate the required reboiler duty in the stripper of a post-combustion carbon capture unit (PCCC-SAPP) in a (630 MWe) natural gas combined cycle (NGCC) power plant to reduce both the condenser duty and power penalty of the plant simultaneously. In the present study, both the solar plant and plant’s low-pressure steam (LPS) are contributing to deliver the required reboiler thermal energy in the first method while the extraction is from the cooling system load in addition to the solar plant in the second method. Solar contribution factor (SCF) is the main criteria which has been used to evaluate the findings. Condenser duty with its associated water requirements, power penalty, and the required solar field land area are the parameters which have been investigated in the preset study. It has been found that the second configuration method has better impact on the performance of the plant and its associated cooling system than the first configuration method where zero power penalty is consumed in the second configuration as well as reducing the condenser duty with its related water usage amounts. In addition, it was shown that raw water withdrawal and consumption amounts in term of (gal/min)/MWnet decrease with increasing SCF in the first configuration where raw water withdrawal and consumption amounts are 7.23 (gal/min)/MWnet, and 5.17 (gal/min)/MWnet at SCF equals to 0 while these amounts reach to 6.74 (gal/min)/MWnet and 4.82 (gal/min)/MWnet at SCF of 0.95 respectively. On the other hand, these amounts increase with increasing SCF in the second configuration where water withdrawal and consumption values approach 6.75 (gal/min)/MWnet, and 4.92 (gal/min)/MWnet at SCF equals to 0 while the amounts are equal to 7.93 (gal/min)/MWnet and 5.81 (gal/min)/MWnet at SCF equals to 0.95 respectively despite that condenser duty is increasing in the both methods. This comes from the fact that the net produced power is increasing in the first scenario with SCF while it keeps constant in the second scenario. Furthermore, the relationship between the solar field’s required land area and solar direct normal irradiation (DNI) was investigated in the present paper under four different SCF; 0.2, 0.4, 0.6, and 0.8. It was found that reducing the solar field’s required land area requires increase in the DNI and decrease in the SCF where the reboiler heat duty is constant in the PCCC and the relationship is almost exponential. The validation was performed with an American governmental report (NETL, 2015) showing that the presented results has a significant agreement with the report.

Thermodynamic investigation of intercooled reheat gas turbine combined cycle with carbon capture and methanation

In this work an intercooled reheat gas/steam combined power cycle with CO2 capture and methanation is studied. CO2 capture and methanation unit is integrated to capture CO2 from the exhaust of gas/steam combined cycle plant and converted it into methane (CH4) so that this methane can be used as additional fuel and hence reduces the amount of carbon emission into the atmosphere. An organic Rankine cycle is integrated between the high-pressure compressor and low-pressure compressor to utilize the heat extraction during the intercooling process. Suitable working fluids for the Organic Rankine cycle have been chosen taking thermophysical properties into consideration such as lower boiling point, critical temperature & pressure and global warming potential. The energy and the mass balance equations have been developed to analyse thermodynamic performance of the proposed combined cycle system. Parametric analysis of the cycle has been performed to evaluate the impact of several cycle variables such as cycle pressure ratio, turbine inlet temperature, condenser temperature, vapor turbine inlet pressure, etc. on the system performance. The study reveals that higher cycle pressure ratio of topping cycle results in less formation of steam in HRSG which further advocates that cycle pressure ratio might be kept low to achieve the high rate of steam generation which again results in increased work output of the cycle. The study reveals that the overall work output of combined system is increased from 220.9 MW to 370 MW by including carbon capture unit at a turbine inlet temperature (TIT) of 1475 K and a cycle pressure ratio of 20.

Reporting the ancient green construction technology of limecrete slabs adopted in Udaipur, Rajasthan

The characterization of limecrete slabs made of plant extract and hemp fibers of an old monument, Bichili haveli, located in Udaipur, Rajasthan, India was carried out to understand the traditional materials used and its production. Limecrete of ratio 1: 1: 3 (Lime: brickbats: sand) were produced with hemp fibers to acts as flexural members. The hardened limecrete shows the predominate phases of calcium carbonate such as calcite with other polymorphs (vaterite & aragonite), tobermorite and Calcium alumina-silica hydrates (CASH). The organic analysis has confirmed the presence of biomolecules which are originated by the addition of fermented plant extracts that acts as a natural admixture during the preparation of limecrete slabs. With the help of organic additives, limecrete also acts as a Carbon Capture and Utilization (CCU) unit and sequester 15–20% of atmospheric carbon di oxide (CO2). The current study reclaims the lost old technology which uses low energy-intensive materials like lime, brick powder & bats, plants extracts and hemp fibers at the same time 20% lesser cost than cement concrete. The experimental evidence from the present research proves that the limecrete slabs have enough strength and durability, also acts as CO2 capture materials in mitigating global emissions. Limecrete can be used for the restoration of the heritage building as well as in modern construction for low rise buildings.