preliminary design of a mw class demo system for co2 capture with mcfc in a university campus cogeneration plant

Abstract One of the most promising, short-term options for efficiently capturing CO 2 from combustion exhaust gases – potentially from any combustion process source - is based on the operating principle of Molten Carbonate Fuel Cells (MCFC): their electrochemical reactions promote the transport of both CO 2 and O 2 molecules from the cathode side (which can be fed with combustion effluents) to the CO 2 -rich atmosphere of the anode side (fed with internally reformed natural gas), by means of a CO 3 2- -ion conducting electrolyte. In the present work, the preliminary design of a 1 MW el MCFC demo plant operating downstream a Combined Heat and Power (CHP) Internal Combustion Engine (ICE) installed at the Politecnico di Milano campus is investigated, with the aim of promoting a valid solution for high efficiency, de-carbonised heat and electricity production. The study envisages two purification strategies for the CO 2 -rich stream at the MCFC anode outlet: i) the CO 2 is separated and compressed in a cryogenic unit and the unconverted fuel is either recycled at the anode inlet or burned and sent to the MCFC cathode inlet ii) the anode exhausts are burned in a catalytic oxy-combustor, increasing both the thermal energy available in the cogeneration unit and the CO 2 concentration in the stream sent to the storage site. Subsequently to a thermodynamic analysis carried out with a 0D model calibrated upon experimental data available for a commercial MCFC unit, the main components are designed by taking into account all the operating constraints of the machines and the CO 2 capture limitations associated to the size of the MCFC modules currently available on the market. Moreover, an economic analysis is performed in order to assess the feasibility of such an installation within the university campus cogeneration grid. As a main finding, the use of MCFCs to capture CO 2 at a distributed generation scale allows reaching interesting energy and environmental performances, highlighted by promising values of the Specific Primary Energy Consumption for CO 2 Avoided (SPECCA=0.9-1.9 MJ/kgCO 2 ) and Carbon Capture Ratios (CCR=68-84%). Within a mid-term perspective for MCFC specific cost, the economic analyses reveal acceptable values for the cost of electricity and the cost of CO 2 avoided, respectively close to 130 €/MWh el and 100 €/tCO 2

Application of Molten Carbonate Fuel Cells in Cement Plants for CO2 Capture and Clean Power Generation

Abstract Cement production process features intrinsically large CO 2 emission due to the decomposition of limestone by calcination reaction and to fuel combustion, necessary for sustaining the endothermic calcination process and the formation of clinker. Conventional approaches to CO 2 emission reduction in cement plants are based on post-combustion capture with chemical solvents, requiring a substantial energy consumption for regeneration, or oxycombustion in the cement kiln, involving a deep redesign of the plant. The aim of this work is investigating the application of Molten Carbonate Fuel Cells in cement plants for CO 2 capture from the plant exhaust gases, using the fuel cells as active CO 2 concentrators of combustion flue gases and eventually obtaining a purified CO 2 stream through a cryogenic process. A novel configuration with MCFCs added along the exhaust line has been assessed by means of process simulations. The results show a remarkable potential in terms of equivalent avoided CO 2 emissions (exceeding 1000 g/kWh), high share of CO 2 avoided (up to about 70%) and low energy penalties

Time-resolved reflectance spectroscopy as a management tool for late-maturing nectarine supply chain

The absorption coefficient of the fruit flesh at 670 nm (mu(a)), measured at harvest by time-resolved reflectance spectroscopy (TRS) is a good maturity index for early nectarine cultivars. A kinetic model has been developed linking the mu(a), expressed as the biological shift factor to softening during ripening. This allows shelf life prediction for individual fruit from the value of mu(a) at harvest and the fruit categorization into predicted softening and usability classes. In this work, the predictive capacity of a kinetic model developed using mu(a) data at harvest and firmness data within 1-2 d after harvest for a late maturing nectarine cultivar ('Morsiani 90') was tested for prediction and classification ability. Compared to early maturing cultivars, mu(a) at harvest had low values and low variability, indicating advanced maturity, whereas firmness was similar. Hence, fruit were categorized into six usability classes (from 'transportable-hard' to 'ready-to-eat-very soft') basing on mu(a) limits established analyzing firmness data in shelf life after harvest. The model was tested by comparing the predicted firmness and class of usability to the actual ones measured during ripening and its performance compared to that of models based on data during the whole shelf life at 20 degrees C after harvest and after storage at 0 degrees C and 4 degrees C. The model showed a classification ability very close to that of models based on data of the whole shelf life, and was able to correctly segregate the 'ready-to-eat-transportable', 'transportable' and 'transportable-hard' classes for ripening at harvest and after storage at 0 degrees C, and the 'ready-to-eat-very soft' and 'ready-to-eat-soft' classes for ripening after storage at 4 degrees C, with lower performance of models for fruit after storage at 4 degrees C respect to those of the other two ripening

The Calcium Looping Process for Low CO2 Emission Cement and Power

Abstract Calcium looping appears as one of the most promising technologies for CO2 capture in short-medium term plants featuring the combustion of fossil fuels. Ca-looping (CaL) is a regenerative process which takes advantage of the capacity of Calcium Oxide-based sorbents in capturing the CO2 from combustion gases by means of sequential carbonation-calcination cycles. CaL technology appears very promising for CO2 capture from cement plants, since the CaO-rich purge stream which must be extracted from the process can be a valuable raw material for clinker production. The aim of this study is to investigate from the technical and economic side the benefits arising from the integration between a coal-fired power plant with CaL process for CO2 capture and a cement plant using the CaL purge to substitute part of the raw meal. The main parameters affecting the CaL process are varied and the effects on both the plant performance and the final cost of clinker and electricityare discussed

Studies on classification models to discriminate ‘Braeburn’ apples affected by internal browning using the optical properties measured by time-resolved reflectance spectroscopy

This work aimed at studying the feasibility of time-resolved reflectance spectroscopy (TRS) to nondestructively detect internal browning (IB) in ‘Braeburn’ apples through the development of classification models based on absorption (ua) and scattering (us') properties of the pulp.This research was carried out in two seasons: in 2009, apples were measured by TRS at 670 nm and inthe 740–1040 nm spectral range on four equidistant points around the equator, whereas in 2010 appleswere measured by TRS at 670 nm and at 780 nm on eight equidistant points. The values of the absorption coefficients measured in the 670–940 nm range increased with IB devel-opment. On the contrary, us'780 was higher in healthy fruit than in IB ones. The ua780 also significantlyincreased with IB severity, showing high values when IB affected the pulp tissues compared to the coreones. Also ua670 changed with IB development, but it was not able to clearly discriminate healthy fruitfrom IB ones because its value was also affected by the chlorophyll content of the pulp. The absorption and scattering coefficients were used as explanatory variables in the linear discriminant analysis in order to classify each apple tissue as healthy or IB; then the models obtained were used forfruit classification. The best classification performance was obtained in 2010 using ua780 and us'780and considering the IB position within the fruit: 90% of healthy fruit and 71% of IB fruit were correctly classified. By using all the ua measured in the 670–1040 nm range plus the us'780, IB fruit classification was slightly better while healthy fruit classification was worse. The better result of 2010 was due tothe increased number of TRS measurement points that allowed better exploration of the fruit tissues. However, the asymmetric nature of this disorder makes detection difficult, especially when the disorderis localized in the inner part of the fruit (core) or when it occurs in spots. A different TRS set-up (position and distance of fibers, time resolution) should be studied in order to reach the deeper tissue within the fruit in order to improve browning detection

One-dimensional model of entrained-flow carbonator for CO2 capture in cement kilns by Calcium looping process

In this work, a 1D model of an entrained-flow carbonator of a Calcium looping process for cement plants is presented and the results of a sensitivity analysis on the main governing process parameters is discussed. Several design and operating parameters have been investigated through a wide sensitivity analysis, namely: adiabatic vs. cooled reactor, high gas velocity gooseneck reactor vs. low velocity downflow reactor, solid-to-gas ratio, sorbent capacity, reactor inlet temperature and solids recirculation. The effect of these design and process parameters on the CO2capture efficiency and on Calcium looping process heat consumption is assessed. The results of the calculations showed that with a proper combination of solid-to-gas ratio in the carbonator and sorbent carbonation capacity (e.g. ∼10 kg/Nm3and ∼20% respectively), carbonator CO2capture efficiencies of about 80% (i.e. total cement kiln CO2capture efficiencies higher than 90%) can be obtained in a gooseneck-type carbonator with a length compatible with industrial applications in cement kilns (∼120 to 140 m). Further experimental investigations on this reactor concept, especially about fluid-dynamic behavior and the chemical properties of raw meal as CO2sorbent, are needed to demonstrate the technical feasibility of the proposed process

Techno-economic Analysis of MEA CO2Capture from a Cement Kiln - Impact of Steam Supply Scenario

This paper present the techno-economic assessment of an MEA-based CO2capture from a cement plant and the importance of the steam supply on the costs. The evaluations present the energy performances of the CO2capture process based on a cement plant with a clinker capacity of 3,000 t/d. The cost evaluation lead to a cost of cement of 45 â¬/tcementwithout capture, while the cost of cement with CO2capture is estimated to 81 â¬/tcement, resulting in a CO2avoided cost of 83 â¬/tCO2,avoided. As the steam consumption accounts for close to half of the CO2avoided cost, the impact of six alternative steam supply scenarios are considered. The evaluations show that the CO2avoided cost can decrease by up to 35% depending on the steam supply and electricity price. However the possibility of these steam supply alternatives are specific to the considered cement plant, emphasizing therefore that CO2avoided cost from cement shall rather be given as a range depending on the steam supply than as a unique value as often illustrated in the literature

Frequency Dependence of Piles' Dynamic Stiffness

Technical BriefTechnical Brief 6: The evaluation of the dynamic behavior of deep foundations for Turbomachinery Modules is not a simple task due to uncertainties in the evaluation of the soil shear modulus and the approximations introduced with published literature formulas for complex stiffness (impedance) functions of piles. The direct measurement of the dynamic response of full scale piles can be an efficient method to reduce considerably these uncertainties and to get a reliable evaluation of the dynamic response of deep foundations. The above should also positively impact both the risks and the engineering schedule in the execution phase of the projects, reducing the dynamic analysis cases. The authors present herein the results of full-scale dynamic tests on piles, which have been performed by applying sinusoidal forces to their top

Dissecting the different biological effects of oncogenic Ras isoforms in cancer cell lines: could stimulation of oxidative stress be the one more weapon of H-Ras? Regulation of oxidative stress and Ras biological effects

Ras proteins are small GTPase functioning as molecular switches that, in response to particular extracellular signalling, as growth factors, activate a diverse array of intracellular effector cascades regulating cell proliferation, differentiation and apoptosis. Human tumours frequently express Ras proteins (Ha-, Ki-, N-Ras) activated by point mutations which contribute to malignant phenotype, including invasiveness and angiogenesis. Despite the common signalling pathways leading to similar cellular responses, studies clearly demonstrate unique roles of the Ras family members in normal and pathological conditions and the lack of functional redundancy seems to be explainable, at least in part, by the ability of Ras isoforms to localize in different microdomains to plasma membrane and intracellular organelles. This different intracellular compartmentalization could help Ras isoforms to contact different downstream effectors finally leading to different biological outcomes. Interestingly, it has also been shown that Ha- and Ki-Ras exert an opposite role in regulating intracellular redox status. In this regard we suggest that H-Ras specific induction of ROS (reactive oxygen species) production could be one of the main determinants of the invasive phenotype which characterize cancer cells harbouring H-Ras mutations. In our hypothesis then, while K-Ras (not able to promote oxidative stress) could mainly contribute to cancer progression and invasiveness through activation of MAPK and PI3K, H-Ras-mediated oxidative stress could play a unique role in modulation of intercellular contacts leading to a loss of cell adhesion and eventually also to a metastatic spread