Modeling of a supercritical power plant with an oxy type pulverized fuel boiler, a carbon dioxide capture unit and a ‘four-end’ type membrane air separator

The analysis of a 600 MW supercritical power plant with parameters of life steam at 30 MPa/ /650o C and of reheated steam 6 MPa/670o C was made. Power plant is equipped with the following units: oxy type pulverized fuel boiler, ‘four-end’ high temperature membrane air separator and carbon dioxide capture system which were modeled. With the assumption of a constant gross power of the analyzed power plant, the thermal efficiency of the boiler and the steam cycle efficiency were calculated. These parameters were designated as a function of the recovery rate of oxygen in the air separation unit. This allowed to determine gross and net efficiency of electricity generation

The characteristics of a modern oxy-fuel power plant

This paper presents the thermodynamic and economic analyses of four variants of a supercritical oxy-type plant. These variants differed in terms of air separation units (ASU, variants: V1—cryogenic; V2—hybrid; equipped with a three-end (V3a) or four-end (V3b) high-temperature membrane) and boilers (V1 and V3a—lignite-fired fluidized-bed; V2 and V3b—hard-coal-fired pulverized-fuel). The gross power of steam turbine unit (STU) was 600 MW. The live and reheated steam parameters were 650 °C/30 MPa and 670 °C/6.5 MPa, respectively. The influence of the ASUs’ operating parameters on the ASUs’ auxiliary power rate and boiler efficiency (V3a and V3b only) was studied. The ASUs’ operating parameters for maximum net efficiency were then determined. The decrease in the net efficiency compared to a reference plant (with a classic fluidized-bed or pulverized-fuel boiler) fluctuated in the range 7.2 (V3b)–11.2 (V1) p.p. An analysis of the waste heat utilization was performed (fuel drying—V1 and V3a; STU steam-water heat exchangers replacing). Thus, the efficiency decreases fluctuated in the range 4.3 (V3b)–10.2 (V1) p.p. The economic analysis showed that in order for the variants to be economically viable, the unit CO2 emission cost should be greater than 42.2 (V1) or 22.0 (V3b) EUR/MgCO2

Techno-economic feasibility assessment of calcium looping combustion using commercial technology appraisal tools

Calcium looping combustion (CaLC) is a new class of lowCO2emission technologies for thermochemical conversion of carbonaceous fuels that can help achieve the emissions reduction targets set out in the Paris Agreement. Compared to mature CO2 capture technologies, which cause net efficiency penalties higher than 7% points, CaLC results in a net efficiency penalty of 2.9% points. However, a thorough economic assessment of CaLC needs to be undertaken to evaluate its economic viability. The levelised cost of electricity is commonly used to assess the economic performance of clean energy systems. However, this method does not account for commercially important parameters, such as tax, interest, and depreciation charges. This study aimed to improve the reliability and accuracy of economic assessments of clean energy systems by implementing the net present value (NPV) approach. This approach was applied to assess the economic performance of two concepts of the CaLC-based power plant with either the conventional steam cycle (SC) or the supercritical CO2 cycle (s-CO2) for heat utilisation along with the bottom-up approach to total capital cost estimation. A parametric study for both concepts was also conducted to assess the impact of the key thermodynamic parameters on the economic performance. Although the s-CO2 case with revised assumptions was shown to result in a 1%-point lower net efficiency compared to the SC case, its break-even cost of electricity was lower by 0.81 €/MWh. Further improvements of the techno-economic performance can be sought by optimisation of the s-CO2 cycle structure

From post-combustion carbon capture to sorption-enhanced hydrogen production: A state-of-the-art review of carbonate looping process feasibility

Carbon capture and storage is expected to play a pivotal role in achieving the emission reduction targets established by the Paris Agreement. However, the most mature technologies have been shown to reduce the net efficiency of fossil fuel-fired power plants by at least 7% points, increasing the electricity cost. Carbonate looping is a technology that may reduce these efficiency and economic penalties. Its maturity has increased significantly over the past twenty years, mostly due to development of novel process configurations and sorbents for improved process performance. This review provides a comprehensive overview of the calcium looping concepts and statistically evaluates their techno-economic feasibility. It has been shown that the most commonly reported figures for the efficiency penalty associated with calcium looping retrofits were between 6 and 8% points. Furthermore, the calcium-looping-based coal-fired power plants and sorption-enhanced hydrogen production systems integrated with combined cycles and/or fuel cells have been shown to achieve net efficiencies as high as 40% and 50–60%, respectively. Importantly, the performance of both retrofit and greenfield scenarios can be further improved by increasing the degree of heat integration, as well as using advanced power cycles and enhanced sorbents. The assessment of the economic feasibility of calcium looping concepts has indicated that the cost of carbon dioxide avoided will be between 10 and 30 € per tonne of carbon dioxide and 10–50 € per tonne of carbon dioxide in the retrofit and greenfield scenarios, respectively. However, limited economic data have been presented in the current literature for the thermodynamic performance of calcium looping concepts

Application of Hyphenated Techniques in Speciation Analysis of Arsenic, Antimony, and Thallium

Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices

Advanced power cycles for coal-fired power plants based on calcium looping combustion: a techno-economic feasibility assessment

Carbon capture and storage is crucial to decarbonising the power sector, as no other technology can significantly reduce emissions from fossil fuel power generation systems. Yet, the mature CO2 capture technologies result in net efficiency penalties of at least 7% points. Emerging technologies, such as calcium looping combustion, can reduce the net efficiency penalty to 2.4% points. Further reductions can be achieved by replacing the conventional steam cycle with advanced power cycles. This study aimed to assess the techno-economic feasibility of the coal-fired power plant based on calcium looping combustion with different advanced Brayton cycles. These included single power cycles, such as recompression supercritical CO2, simple supercritical CO2 cycle, and xenon cycle, as well as combined power cycles based on helium, nitrogen and recompression supercritical CO2 cycles. The net efficiency and break-even electricity price, which was estimated using the net present value method, were used as the key techno-economic performance indicators. A parametric study was also conducted to assess the impact of the key thermodynamic parameters. This study showed that the case based on a single recompression supercritical CO2 cycle had the best overall techno-economic performance, while the recompression supercritical CO2 combined cycle case had the best techno-economic performance among combined cycle cases. The former was characterised with a net efficiency of 38.9%, which is higher than that of the reference coal-fired power plant without CO2 capture (38.0%). Such performance was achieved at a break-even electricity price of 71.2 €/MWel,neth, corresponding to a cost of CO2 avoided of 16.3 €/tCO2

Supercritical CO2 cycle for coal-fired power plant based on calcium looping combustion

Calcium looping combustion (CaLC), which comprises an indirectly-heated calciner, is characterised with lower energy intensity and economic penalties compared to that of mature CO2 capture technologies. As CaLC is a standalone power boiler, integration of advanced power cycles can lead to further improvement in net efficiency and reduction in the cost of electricity. Therefore, this study aimed to propose routes for the integration of the supercritical CO2 cycle (sCO2) with CaLC and to evaluate their benefits with respect to the conventional steam cycle. Such processes were modelled in Aspen PlusTM. Moreover, the effect of the operating conditions on the techno-economic performance of the considered cases was evaluated. This study has shown that implementation of the optimised recompression sCO2 cycle with a clean gas cooler resulted in the net efficiency and break-even price of electricity of 37.3%HHV and 75.13 €/MWh, respectively. These are 0.7%HHV points lower and 26% higher, respectively, than that of the conventional coal-fired power plant without CO2 capture. Such performance, however, is superior to retrofits of coal-fired power plants with mature CO2 capture technologies as well as CaLC with a conventional steam cycle, proving the benefits of linking CaLC with advanced power cycles

Blocks adjustment -- reduction of bias and variance of detrended fluctuation analysis using Monte Carlo simulation

The length of minimal and maximal blocks equally distant on log-log scale versus fluctuation function considerably influences bias and variance of DFA. Through a number of extensive Monte Carlo simulations and different fractional Brownian motion/fractional Gaussian noise generators, we found the pair of minimal and maximal blocks that minimizes the sum of mean-squared error of estimated Hurst exponents for the series of length N=2^p, p=7,...,15. Sensitivity of DFA to sort-range correlations was examined using ARFIMA(p,d,q) generator. Due to the bias of the estimator for anti-persistent processes, we narrowed down the range of Hurst exponent to 1/2<=H< 1.Comment: 20 pages, 14 figures, accepted for publication in Physica A: August 9, 200

Assessment of wafer-level transfer techniques of graphene with respect to semiconductor industry requirements

Graphene is a promising candidate for future electronic applications. Manufacturing graphene-based electronic devices typically requires graphene transfer from its growth substrate to another desired substrate. This key step for device integration must be applicable at the wafer level and meet the stringent requirements of semiconductor fabrication lines. In this work, wet and semidry transfer (i.e. wafer bonding) are evaluated regarding wafer scalability, handling, potential for automation, yield, contamination and electrical performance. A wafer scale tool was developed to transfer graphene from 150 mm copper foils to 200 mm silicon wafers with-out adhesive intermediate polymers. The transferred graphene coverage ranged from 97.9% to 99.2% for wet transfer and from 17.2% to 90.8% for semidry transfer, with average cop-per contaminations of 4.7x10$^{13}$ (wet) and 8.2x10$^{12}$ atoms/cm$^2$ (semidry). The corresponding electrical sheet resistance extracted from terahertz time-domain spectroscopy varied from 450 to 550 ${\Omega}/sq$ for wet transfer and from 1000 to 1650 ${\Omega}/sq$ for semidry transfer. Although wet transfer is superior in terms of yield, carbon contamination level and electrical quality, wafer bonding yields lower copper contamination levels and provides scalability due to existing in-dustrial tools and processes. Our conclusions can be generalized to all two-dimensional (2D) materials