Suchergebnisse

Adsorption is an environmentally benign separation technology with no associated toxic emissions that presents potential to reduce the energy penalty of CO2 capture processes. Several adsorption based post-combustion CO2 capture processes have reached the pilot scale demonstration stage. These adsorption processes differ in the adsorbent used, mainly zeolites, carbon materials, solid amine sorbents, and supported alkali carbonates, but also in the process configuration: the method of regeneration (temperature, vacuum, concentration swing or a mixture of those) and the type of adsorbers used (fixed beds, rotary beds, moving beds, and fluidized beds). However, their lower stage of development compared to the benchmark technology, amine absorption, has prevented up to date their commercial development. In this work, adsorption-based post-combustion CO2 capture processes, based on sustainable carbon adsorbents in a multibed configuration, have been designed and assessed through process simulation in order to compare them to the benchmark technology using a common reference, i.e., an advanced supercritical coal power plant of 800 MWe, and similar specifications to enable a fair comparison. The cyclic adsorption processes have been modelled and simulated up to cyclic steady state (CSS) using a dynamic non-equilibrium non-isothermal mathematical model that takes into consideration competitive adsorption between the main flue gas components: N2, CO2 and H2O. Such model had been previously validated against experimental results. The CSS results entailed assessing the capture rate and the CO2 purity of the product for each particular adsorbent and process configuration combination, allowing identifying those that can meet the minimum capture rate (85%) and CO2 purity specifications (95%). Such processes were then compared to the benchmark technology in terms of overall energy consumption. Among the process configurations evaluated up to date, the configuration that employs a vacuum, temperature and concentration swing regeneration strategy, together with low temperature heat, is the most promising. This process, which makes use of a sustainable biomass based carbon, presents a lower specific energy penalty per avoided CO2 than the benchmark technology. Furthermore, greater energy savings could be expected from the development of adsorbents with superior adsorption performance in terms of working capacity and adsorption kinetics. ; Marta G. Plaza acknowledges the award of a Ramon y Cajal contract (RyC-2015-17516) from the Spanish Government ; Peer reviewed

3rd ANQUE-ICCE International Congress of Chemical Engineering ; According to the last report of the IPCC, global CO2 emissions must be net zero by 2040-2050 in order to have chances to limit global warming to 1.5 °C. Delayed action will rise the risks of climate change [1]. Despite the decarbonization efforts, coal remains the main energy source for electricity generation globally. Moreover, there are still coal power plants under construction and in planning stage, and it is unlikely that these facilities will shut down in a timeframe consistent with the climate goals. CO2 capture and storage technologies will be necessary to mitigate the emissions from existing facilities. In this work the feasibility of adsorption technology to capture the CO2 emitted by an advanced supercritical coal power plant of 800 MW is assessed through process simulation, and compared to the benchmark technology: amine scrubbing. Different adsorption technologies are being considered for postcombustion CO2 capture: fixed beds, moving beds, fluidized beds, and rotary beds, where the adsorbent can be regenerated by temperature (TSA), pressure (VSA), concentration (CSA) swing or a combination of them. Different types of adsorbents are also under consideration, with solid amines, carbons, and zeolites at the forefront positions. In this work cyclic multibed processes with indirect heat transfer that make use of carbon adsorbents are considered. Indirect heat transfer entails reducing cycle time and save thermal energy within the process [2]. Several process configurations have been evaluated: TCSA, VTSA, and VTCSA. In the CSA processes evaluated, steam is used in direct contact with the adsorbent to recover the adsorbed CO2. The potential of such processes is assessed through simulation. First, a cyclic process configuration is proposed and simulated with Aspen Adsorption up to cyclic steady state (CSS), using a detailed non-equilibrium non-isothermal model that considers competitive adsorption between the main flue gas components (i.e., N2, CO2 and H2O) that has been validated against experimental results [3]. Process configurations capable of capturing at least 85% CO2 with purity above 95% (dry basis) are then identified and up-scaled to treat the full flow rate of flue gas from the reference power plant. Aspen Plus is then used to calculate the energy demand of the overall process based on the CSS results. Up to date, among the configurations evaluated, the most promising is VTCSA making use of a biomass based carbon adsorbent. This process can meet the purity and capture constraints making use of waste heat and mild vacuum, with a lower specific energy penalty per avoided CO2 than the benchmark technology. ; Marta G. Plaza acknowledges the award of a Ramon y Cajal contract (RyC-2015-17516) from the Spanish Government ; Peer reviewed

The implementation of carbon capture, use, and storage in the cement industry is a necessity, not an option, if the climate targets are to be met. Although no capture technology has reached commercial scale demonstration in the cement sector yet, much progress has been made in the last decade. This work intends to provide a general overview of the CO2 capture technologies that have been evaluated so far in the cement industry at the pilot scale, and also about the current plans for future commercial demonstration. ; S.M. acknowledges the award of an Introduction to Research fellowship (grant number: JAEICU-19-INCAR-26) from the JAE Intro ICUs Programme of the Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC). M.G.P. acknowledges support from the Ramon y Cajal Programme (grant number: RyC-2015-17516) of the Government of Spain, co-financed by the European Social Fund. Financial support from the Government of the Principado de Asturias (PCTI, grant number: IDI/2018/000115), co-financed by the European Regional Development Fund (ERDF), is also acknowledged. ; Peer reviewed

The present work evaluates the feasibility to capture at least 85% of the CO2 emitted by an advanced supercritical pulverized coal power plant of 800 MWe, delivering a CO2 product with a purity of 95% (dry basis) or higher, using an adsorption-based postcombustion capture process based on carbon honeycomb monoliths regenerated by steam stripping. Process performance has been evaluated through the dynamic simulation of the cyclic adsorption process. The fixed bed adsorption model, which was validated against experimental results, is based on the mass, momentum, and energy conservation equations, and it accounts for competitive adsorption between the three main flue gas components: N2, CO2, and H2O. The evaluated TSA process meets the targets for the capture rate and product purity, with a heat duty of 3.59 MJ kg–1 CO2, which is close to the specific reboiler duty of the benchmark amine-based absorption process. Materials and process development will lead to lower duties. A sensitivity analysis was carried out, and it has shown that slightly faster adsorption kinetics for CO2 could drop the specific heat duty of the process to 2.89 MJ kg–1 CO2, which is lower than that of the benchmark technology. From the process point of view, the use of waste heat from the power plant could further reduce the energy penalty of the integrated CO2 capture process. ; Work carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme (FP7) (2007−2013; Grant Agreement No. 608555) ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed

The EU FP7-funded HiPerCap project aims to develop novel post-combustion CO2 capture technologies and processes which are environmentally benign and have high potential to lead to breakthroughs in energy consumption and overall cost. Three different separation technologies are being evaluated on a fair basis: absorption, membranes and adsorption. In this work, some of the results related to the development of adsorption-based fixed bed systems are presented. The design and optimization of a multibed adsorption-based separation process requires the use of powerful simulators that can describe the non-steady state process. However, prior to use a mathematical model for process design this should be validated against experimental data. A VTSA experiment has been carried out in order to provide information on the cyclic performance of a microporous biochar. The working capacity of the adsorbent is reduced due to incomplete regeneration during cyclic operation, although it stabilizes at 0.5 mol CO2 kg-1 and 0.4 mol H2O kg-1 once cyclic steady state is reached. A non-isothermal non-adiabatic dynamic model of the VTSA cycle was built in Aspen Adsorption, which makes use of the Ideal Adsorbed Solution theory to account for competitive adsorption between N2, CO2 and H2O. The model satisfactorily describes the history of the temperature of the adsorbent, the pressure, the total mass flow rate of the effluent, and the working capacity at cyclic steady state of the VTSA experiment. The validated model will be used as a starting point for process development. ; Work carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme (FP7) (2007-2013; Grant Agreement No. 608555). ; Peer reviewed

The effect of post-treatment upon the H2O adsorption performance of biomass-based carbons was studied under post-combustion CO2 capture conditions. Oxygen surface functionalities were partially replaced through heat treatment, acid washing, and wet impregnation with amines. The surface chemistry of the final carbon is strongly affected by the type of post-treatment: acid treatment introduces a greater amount of oxygen whereas it is substantially reduced after thermal treatment. The porous texture of the carbons is also influenced by post-treatment: the wider pore volume is somewhat reduced, while narrow microporosity remains unaltered only after acid treatment. Despite heat treatment leading to a reduction in the number of oxygen surface groups, water vapor adsorption was enhanced in the higher pressure range. On the other hand acid treatment and wet impregnation with amines reduce the total water vapor uptake thus being more suitable for post-combustion CO2 capture applications. ; This work was carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme FP7 (2007–2013; Grant Agreement Number: 60855) and from the Gobierno del Principado de Asturias (PCTI-GRUPIN14-079). N.Q. acknowledges a fellowship from the Gobierno del Principado de Asturias (Programa Severo Ochoa). ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed

The main drawbacks of developing carbon adsorbents from pine sawdust, an abundant biomass feedstock, are the low carbon yield of the process and the poor mechanical properties of the resulting carbons. In an attempt to overcome these limitations, the effect of the addition of coal tar pitch was assessed. Adsorbent pellets were produced from pine sawdust and coal tar pitch by activation with CO2. The preparation process was optimized by using as decision variables the carbon yield and the adsorption performance of the adsorbents in conditions representative of post-combustion capture applications (10% CO2 at atmospheric pressure and at 50 °C). Subjecting the composite pellets to a pre-oxidation treatment with air increased the carbon yield of the production process, and also improved the adsorption kinetics and capacity of the final adsorbents. The prepared adsorbents present a high carbon yield, a superior mechanical resistance and a competitive adsorption performance. ; This work was carried out with financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF). M.G.P. acknowledges funding from the CSIC (JAE-Doc program), co-financed by the European Social Fund, and I.D. acknowledges funding from the Government of the Principado de Asturias. The authors are grateful to Industrial Química del Nalón S.A. for supplying the coal tar pitch sample. ; Peer reviewed

The adsorption behavior of humid mixtures that are representative of postcombustion conditions on a microporous biochar was evaluated. The adsorption isotherms of H2O(v) were measured at 30, 50, and 70 °C up to the saturation pressure and fitted to the extended Cooperative Multimolecular Sorption (CMMS) model. Dynamic experiments were carried out in a fixed-bed adsorption unit with mixtures of N2, CO2, and H2O(v). Experimental results indicate that H2O is little affected by CO2 adsorption. On the other hand, the CO2 adsorption capacity can be reduced by the adsorption of H2O. The extent of this reduction is dependent on the amount of H2O adsorbed, which, in turn, is strongly dependent on the relative humidity of the gas phase and the adsorption time. A dynamic fixed-bed adsorption model that makes use of Ideal Adsorbed Solution (IAS) theory has been shown to be adequate to describe the adsorption behavior of CO2 from the ternary mixtures in the full range of conditions evaluated. ; Work carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme (FP7) (2007-2013; Grant Agreement No. 60855). ; Peer reviewed

The influence of N2 on CO2 adsorption was evaluated using a microporous biochar with a narrow pore size distribution. The adsorption isotherms of pure CO2 and N2 were measured at 0, 30, 50, and 70 °C up to 120 kPa and fitted to the Toth adsorption model. Dynamic breakthrough experiments were carried out in a fixed-bed adsorption unit using binary mixtures with compositions representative of different postcombustion streams (8–30% CO2) from ambient temperature to 70 °C. Dynamic adsorption experiments were simulated to validate the mathematical model of the adsorption process, as a necessary step for its later use for process design. The Ideal Adsorption Solution (IAS) theory, based on the pure component adsorption models, was used to account for competitive adsorption with satisfactory results. The information gathered in the present work will be used to extend the validity of the model to the adsorption of postcombustion streams containing H2O in part 2. ; Work was carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme FP7 (2007-2013; Grant Agreement number: 60855). M.G.P. acknowledges funding from the CSIC (JAE-Doc program cofinanced by the European Social Fund). N.Q. acknowledges funding from the Government of the Principado de Asturias (Severo Ochoa Program). The authors also appreciate the support from the technical consultants of AspenTechnology Inc., M.M. and E.L. ; Peer reviewed

13th International Conference on Greenhouse Gas Control Technologies, GHGT-13, 14-18 November 2016, Lausanne, Switzerland ; The development of adsorption-based technologies for post-combustion CO2 capture requires finding an adsorbent with adequate equilibrium and transport properties. Structured adsorbents are appealing for fixed-bed TSA processes, because they present lower pressure drop and higher thermal conductivity than conventional adsorbent beds, which facilitates the use of higher flowrates and shorter cycle times, maximizing throughput. In this work, the equilibrium of adsorption of the main flue gas components, CO2, N2, O2 and H2O over two carbon honeycomb monoliths with different textural development has been measured in a pressure and temperature range of interest for post-combustion CO2 capture: between 0 °C and 70 °C and up to 120 kPa for CO2, N2, and O2, and between 30 °C and 70 °C up to the corresponding saturation pressure for H2O. The maximum adsorption capacity and isosteric heat of adsorption follows the order: H2O > CO2 > N2 ≈ O2. The carbon monoliths present equilibrium selectivity towards CO2 and H2O over N2 and O2 at typical flue gas conditions. Moderate activation is preferred to maximize the CO2 adsorption capacity and selectivity in these conditions. The Toth model was employed to fit the equilibrium data for the adsorption of CO2, N2, and O2 with highly satisfactory results. The adsorption isotherms of H2O presents the characteristic "s" shape of hydrophobic adsorbents, with low uptakes at low relative pressures, which will facilitate H2O desorption during cyclic operation. These were fitted using the extended CMMS model, which describes satisfactorily the experimental data in the full relative humidity range. The adsorption kinetics were preliminary evaluated by measuring the rate of mass uptake from a mixture with 10% CO2 (balance N2) at 30 °C, 50 °C and 70 °C, and the data were fitted to the linear driving force model to obtain the kinetic rate constants. ; Work carried out with financial support from the HiPerCap Project of the European Union 7th Framework Programme FP7 (2007-2013; Grant Agreement number: 60855). N.Q. acknowledges a fellowship from the Gobierno del Principado de Asturias (Programa Severo Ochoa). ; Peer reviewed