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Author: Peter Harlick
Publisher:
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Languages : en
Pages :
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The objective of this work was to evaluate the fundamentals of the currently available CO2 separation technologies and provide a solution for the efficient capture of carbon dioxide from various point source emitting industries. In order to realize a robust approach to advancing the solution to this global issue, the versatility of the process to the range of compounds contained within the stream(s) to be processed must be maintained. It is clear that adsorption, membrane, and aqueous amine based processes are all capable. However, only aqueous amine scrubbing appears economically viable at the current stage of development. In order to challenge this, and potentially drive the separation costs lower, this work centered on hybridizing aqueous amine chemistry and dry adsorption based separations to produce a novel nano-porous material capable of efficient removal of CO2 from flue gas (5% CO2 balance N2 with moisture). In order to combine aqueous amine scrubbing with dry adsorption, a few approaches were considered and evaluated. These included, amine impregnation within the vast pore volume of PE-MCM-41, surface grafting of various amino silane compounds, and finally, a novel approach of volume based amine functionalization (3D grafting). Application of pore-expanded MCM-41 (PE-MCM-41) mesoporous silica coated with 3-[2-(2-aminoethyl-amino)ethylamino]propyltrimethoxysilane (TRI) has been extensively examined for the adsorption of CO2 from N2. A systematic study of the amine loading as a function of the relative amounts of TRI and water used during the grafting procedure, and the temperature of the grafting reaction was carried out. Extremely high levels of active amine content were achieved using prehydrated silica surfaces at grafting temperatures below reflux in order to facilitate thermally controlled water-aided surface polymerization of the aminosilanes. Abstract iii The CO2 adsorption capacities and rates were determined for all materials as a function of the amount of TRI and water per gram of support added to the grafting mixture. The optimal TRI grafted PE-MCM-41 adsorbent exhibited a 2.65 mmol/g adsorption capacity at 25 °C and 1.0 atm for a dry 5% CO2 in N2 feed mixture, which exceeded all literature reported values, for both meso- and microporous materials under the conditions used in this study. Further, the apparent adsorption and desorption rates with the amine functionalized materials were exceedingly high. When considering the grafted amine quantity, the adsorption capacity and rate were found to be mutually dependent on each other, exhibiting an apparent optimal combination. In comparison to zeolite 13X, the optimally loaded TRI-PE-MCM-41 was far superior in terms of dynamic adsorption and desorption performance. These results were further enhanced when the adsorbents were challenged with a humid stream of 5% CO2/N2. The TRIPE-MCM-41 exhibited a 10% increase in CO2 adsorption capacity, whereas the 13X zeolite did not retain any significant CO2 adsorption capacity. The novel concept of an internally variably staged permeator was introduced. A theoretical model was developed and used as the basis for simulation studies. The advantage of the internal variably staged design was shown to permit a very high extent of separation similar to a two stage permeator for purity, while maintaining similar flux rates as per a single stage permeator. This IVSP concept has also taken existing membrane materials and mechanically translated their process performance to a higher level. As such, the unit should prove effective for front end process stream cleanup requirements prior to an adsorption process with the novel TRI-PE-MCM-41 nano-porous adsorbent.
Author: Peter Harlick
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The objective of this work was to evaluate the fundamentals of the currently available CO2 separation technologies and provide a solution for the efficient capture of carbon dioxide from various point source emitting industries. In order to realize a robust approach to advancing the solution to this global issue, the versatility of the process to the range of compounds contained within the stream(s) to be processed must be maintained. It is clear that adsorption, membrane, and aqueous amine based processes are all capable. However, only aqueous amine scrubbing appears economically viable at the current stage of development. In order to challenge this, and potentially drive the separation costs lower, this work centered on hybridizing aqueous amine chemistry and dry adsorption based separations to produce a novel nano-porous material capable of efficient removal of CO2 from flue gas (5% CO2 balance N2 with moisture). In order to combine aqueous amine scrubbing with dry adsorption, a few approaches were considered and evaluated. These included, amine impregnation within the vast pore volume of PE-MCM-41, surface grafting of various amino silane compounds, and finally, a novel approach of volume based amine functionalization (3D grafting). Application of pore-expanded MCM-41 (PE-MCM-41) mesoporous silica coated with 3-[2-(2-aminoethyl-amino)ethylamino]propyltrimethoxysilane (TRI) has been extensively examined for the adsorption of CO2 from N2. A systematic study of the amine loading as a function of the relative amounts of TRI and water used during the grafting procedure, and the temperature of the grafting reaction was carried out. Extremely high levels of active amine content were achieved using prehydrated silica surfaces at grafting temperatures below reflux in order to facilitate thermally controlled water-aided surface polymerization of the aminosilanes. Abstract iii The CO2 adsorption capacities and rates were determined for all materials as a function of the amount of TRI and water per gram of support added to the grafting mixture. The optimal TRI grafted PE-MCM-41 adsorbent exhibited a 2.65 mmol/g adsorption capacity at 25 °C and 1.0 atm for a dry 5% CO2 in N2 feed mixture, which exceeded all literature reported values, for both meso- and microporous materials under the conditions used in this study. Further, the apparent adsorption and desorption rates with the amine functionalized materials were exceedingly high. When considering the grafted amine quantity, the adsorption capacity and rate were found to be mutually dependent on each other, exhibiting an apparent optimal combination. In comparison to zeolite 13X, the optimally loaded TRI-PE-MCM-41 was far superior in terms of dynamic adsorption and desorption performance. These results were further enhanced when the adsorbents were challenged with a humid stream of 5% CO2/N2. The TRIPE-MCM-41 exhibited a 10% increase in CO2 adsorption capacity, whereas the 13X zeolite did not retain any significant CO2 adsorption capacity. The novel concept of an internally variably staged permeator was introduced. A theoretical model was developed and used as the basis for simulation studies. The advantage of the internal variably staged design was shown to permit a very high extent of separation similar to a two stage permeator for purity, while maintaining similar flux rates as per a single stage permeator. This IVSP concept has also taken existing membrane materials and mechanically translated their process performance to a higher level. As such, the unit should prove effective for front end process stream cleanup requirements prior to an adsorption process with the novel TRI-PE-MCM-41 nano-porous adsorbent.
Author: Tushar Kanti Sen
Publisher: CRC Press
ISBN: 1138196851
Category : Science
Languages : en
Pages : 320
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Book Description
Air and water pollution occurs when toxic pollutants of varying kinds (organic, inorganic, radioactive and so on) are directly or indirectly discharged into the environment without adequate treatment to remove these potential pollutants. There are a total of 13 book chapters in three sections contributed by significant number of expert authors around the world, aiming to provide scientific knowledge and up-to-date development of various solid wastes based cost-effective adsorbent materials and its sustainable application in the removal of contaminates/pollutants from air, gas and water. This book is useful for the professions, practicing engineers, scientists, researchers, academics and undergraduate and post-graduate students’ interest on this specific area. Key Features: • Exclusive compilation of information on use of industrial and agricultural waste based adsorbents for air and water pollution abatement. • Explores utilization of industrial solid wastes in adsorptive purification and agricultural and agricultural by-products in separation and purification. • Discusses cost-effective solid wastes based emerging adsorbents. • Alternative adsorbents in the removal of a wide range of contaminants and pollutants from water is proposed. • Includes performance of unit operations in waste effluents treatment.
Author: Qiang Wang
Publisher: Royal Society of Chemistry
ISBN: 1788015452
Category : Technology & Engineering
Languages : en
Pages : 318
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Book Description
Inorganic solid adsorbents/sorbents are attractive materials for capturing carbon dioxide (CO2) from flue gases after fossil fuel combustion. Post-combustion Carbon Dioxide Capture Materials introduces the key inorganic materials used as adsorbents/sorbents with specific emphasis on their design, synthesis, characterization, performance, and mechanism. Dedicated chapters cover carbon-based adsorbents, zeolite- and silica-based adsorbents, metal–organic framework (MOF)-based adsorbents, and alkali-metal-carbonate-based adsorbents. The final chapter discusses the practical application aspects of these adsorbents used in carbon dioxide capture from flue gases. Edited and written by world-renowned scientists in each class of the specific material, this book will provide a comprehensive introduction for advanced undergraduates, postgraduates and researchers from both academic and industrial fields wishing to learn about the topic.
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Languages : en
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In chapter 1, the studies focused on the development of novel sorbents for reducing the carbon dioxide emissions at high temperatures. Our studies focused on cesium doped CaO sorbents with respect to other major flue gas compounds in a wide temperature range. The thermo-gravimetric analysis of sorbents with loadings of CaO doped on 20 wt% cesium demonstrated high CO2 sorption uptakes (up to 66 wt% CO2/sorbent). It is remarkable to note that zero adsorption affinity for N2, O2, H2O and NO at temperatures as high as 600 C was observed. For water vapor and nitrogen oxide we observed a positive effect for CO2 adsorption. In the presence of steam, the CO2 adsorption increased to the highest adsorption capacity of 77 wt% CO2/sorbent. In the presence of nitrogen oxide, the final CO2 uptake remained same, but the rate of adsorption was higher at the initial stages (10%) than the case where no nitrogen oxide was fed. In chapter 2, Ca(NO3)2 · 4H2O, CaO, Ca(OH)2, CaCO3, and Ca(CH3COO)2 · H2O were used as precursors for synthesis of CaO sorbents on this work. The sorbents prepared from calcium acetate (CaAc2-CaO) resulted in the best uptake characteristics for CO2. It possessed higher BET surface area and higher pore volume than the other sorbents. According to SEM images, this sorbent shows 'fluffy' structure, which probably contributes to its high surface area and pore volume. When temperatures were between 550 and 800 C, this sorbent could be carbonated almost completely. Moreover, the carbonation progressed dominantly at the initial short period. Under numerous adsorption-desorption cycles, the CaAc2-CaO demonstrated the best reversibility, even under the existence of 10 vol % water vapor. In a 27 cyclic running, the sorbent sustained fairly high carbonation conversion of 62%. Pore size distributions indicate that their pore volume decreased when experimental cycles went on. Silica was doped on the CaAc2-CaO in various weight percentages, but the resultant sorbent did not exhibit better performance under cyclic operation than those without dopant. In chapter 3, the Calcium-based carbon dioxide sorbents were made in the gas phase by flame spray pyrolysis (FSP) and compared to the ones made by standard high temperature calcination (HTC) of selected calcium precursors. The FSP-made sorbents were solid nanostructured particles having twice as large specific surface area (40-60 m2/g) as the HTC-made sorbents (i.e. from calcium acetate monohydrate). All FSP-made sorbents showed high capacity for CO2 uptake at high temperatures (773-1073 K) while the HTC-made ones from calcium acetate monohydrate (CaAc2 · H2O) demonstrated the best performance for CO2 uptake among all HTC-made sorbents. At carbonation temperatures less than 773 K, FSP-made sorbents demonstrated better performance for CO2 uptake than all HTC-made sorbents. Above that, both FSP-made, and HTC-made sorbents from CaAc2 · H2O exhibited comparable carbonation rates and maximum conversion. In multiple carbonation/decarbonation cycles, FSP-made sorbents demonstrated stable, reversible and high CO2 uptake capacity sustaining maximum molar conversion at about 50% even after 60 such cycles indicating their potential for CO2 uptake. In chapter 4 we investigated the performance of CaO sorbents with dopant by flame spray pyrolysis at higher temperature. The results show that the sorbent with zirconia gave best performance among sorbents having different dopants. The one having Zr to Ca of 3:10 by molar gave stable performance. The calcium conversion around 64% conversion during 102-cycle operations at 973 K. When carbonation was performance at 823 K, the Zr/Ca sorbent (3:10) exhibited stable performance of 56% by calcium molar conversion, or 27% by sorbent weight, both of which are less than those at 973 K as expected. In chapter 5 we investigated the performance of CaO sorbents by flame spray pyrolysis at higher temperature with much shorter duration period. Stable high conversions were attained after 40 cycles The results show that the sorbent could reach high CO2 capture capacity, be completely regenerated in short time and be quite stable even at these severe conditions. Several studies were devoted to identify sorbents which could effectively capture CO2 while survive in SO2 atmosphere. From the group of sorbents we checked, a couple of sorbents showed very promising behavior, namely CO2 uptakes higher than 60% (wt/wt sorbent) while they acquired higher than 95% of their original activity/performance characteristics in a short period of time.
Author: Shin-ichi Nakao
Publisher: Springer
ISBN: 3030188582
Category : Technology & Engineering
Languages : en
Pages : 83
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Book Description
This book summarises the advanced CO2 capture technologies that can be used to reduce greenhouse gas emissions, especially those from large-scale sources, such as power-generation and steel-making plants. Focusing on the fundamental chemistry and chemical processes, as well as advanced technologies, including absorption and adsorption, it also discusses other aspects of the major CO2 capture methods: membrane separation; the basic chemistry and process for CO2 capture; the development of materials and processes; and practical applications, based on the authors’ R&D experience. This book serves as a valuable reference resource for researchers, teachers and students interested in CO2 problems, providing essential information on how to capture CO2 from various types of gases efficiently. It is also of interest to practitioners and academics, as it discusses the performance of the latest technologies applied in large-scale emission sources.
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Languages : en
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Capturing CO2 emissions generated from fossil fuel-based power plants has received widespread attention and is considered a vital course of action for CO2 emission abatement. Efforts are underway at the Department of Energy's National Energy Technology Laboratory to develop viable energy technologies enabling the CO2 capture from large stationary point sources. Solid, immobilized amine sorbents (IAS) formulated by impregnation of liquid amines within porous substrates are reactive towards CO2 and offer an alternative means for cyclic capture of CO2 eliminating, to some degree, inadequacies related to chemical absorption by aqueous alkanolamine solutions. This paper describes synthesis, characterization, and CO2 adsorption properties for IAS materials previously tested to bind and release CO2 and water vapor in a closed loop life support system. Tetraethylenepentamine (TEPA), acrylonitrile-modified tetraethylenepentamine (TEPAN), and a single formulation consisting of TEPAN and N, N'-bis(2-hydroxyethyl)ethylenediamine (BED) were individually supported on a poly (methyl methacrylate) (PMMA) substrate and examined. CO2 adsorption profiles leading to reversible CO2 adsorption capacities were obtained using thermogravimetry. Under 10% CO2 in nitrogen at 25°C and 1 atm, TEPA supported on PMMA over 60 minutes adsorbed ~3.2 mmol/g{sorbent} whereas, TEPAN supported on PMMA along with TEPAN and BED supported on PMMA adsorbed ~1.7 mmol/g{sorbent} and ~2.3 mmol/g{sorbent} respectively. Cyclic experiments with a 1:1 weight ratio of TEPAN and BED supported on poly (methyl methacrylate) beads utilizing a fixed-bed flow system with 9% CO2, 3.5% O2, nitrogen balance with trace gas constituents were studied. CO2 adsorption capacity was ~ 3 mmols CO2/g{sorbent} at 40°C and 1.4 atm. No beneficial effect on IAS performance was found using a moisture-laden flue gas mixture. Tests with 750 ppmv NO in a humidified gas stream revealed negligible NO sorption onto the IAS. A high SO2 concentration resulted in incremental loss in IAS performance and revealed progressive degrees of "staining" upon testing. Adsorption of SO2 by the IAS necessitates upstream removal of SO2 prior to CO2 capture.
Author: John W. Patrick
Publisher: John Wiley & Sons
ISBN:
Category : Science
Languages : en
Pages : 352
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Book Description
Porosity in carbons often means different things to different people depending largely on the different applications of the various carbon materials. On the one hand, users involved in gas purification or respiratory protection are concerned primarily with microporosity, and at the other extreme, the user of carbon in the form of metallurgical coke is concerned with macroporosity because of its influence on the mechanical properties of the coke. Between these extremes there is a range of applications which rely on different aspects of the nature of the porous structure and the characterization required reflects the particular application in mind. This characterization of a wide diversity of porous structures presents some problems. However recent developments have produced some solutions, for example computerized image analysis has facilitated the measurement of pore shape and size. The eleven chapters in this book present an analysis of the current methods of characterization and the role of various aspects of carbon porosity in some representative and diverse applications.
Author: De-en Jiang
Publisher: John Wiley & Sons
ISBN: 1119091179
Category : Science
Languages : en
Pages : 397
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Book Description
Covers a wide range of advanced materials and technologies for CO2 capture As a frontier research area, carbon capture has been a major driving force behind many materials technologies. This book highlights the current state-of-the-art in materials for carbon capture, providing a comprehensive understanding of separations ranging from solid sorbents to liquid sorbents and membranes. Filled with diverse and unconventional topics throughout, it seeks to inspire students, as well as experts, to go beyond the novel materials highlighted and develop new materials with enhanced separations properties. Edited by leading authorities in the field, Materials for Carbon Capture offers in-depth chapters covering: CO2 Capture and Separation of Metal-Organic Frameworks; Porous Carbon Materials: Designed Synthesis and CO2 Capture; Porous Aromatic Frameworks for Carbon Dioxide Capture; and Virtual Screening of Materials for Carbon Capture. Other chapters look at Ultrathin Membranes for Gas Separation; Polymeric Membranes; Carbon Membranes for CO2 Separation; and Composite Materials for Carbon Captures. The book finishes with sections on Poly(amidoamine) Dendrimers for Carbon Capture and Ionic Liquids for Chemisorption of CO2 and Ionic Liquid-Based Membranes. A comprehensive overview and survey of the present status of materials and technologies for carbon capture Covers materials synthesis, gas separations, membrane fabrication, and CO2 removal to highlight recent progress in the materials and chemistry aspects of carbon capture Allows the reader to better understand the challenges and opportunities in carbon capture Edited by leading experts working on materials and membranes for carbon separation and capture Materials for Carbon Capture is an excellent book for advanced students of chemistry, materials science, chemical and energy engineering, and early career scientists who are interested in carbon capture. It will also be of great benefit to researchers in academia, national labs, research institutes, and industry working in the field of gas separations and carbon capture.
Author: Diana Iruretagoyena Ferrer
Publisher: Springer
ISBN: 3319412760
Category : Technology & Engineering
Languages : en
Pages : 234
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Book Description
This thesis presents a combination of material synthesis and characterization with process modeling. In it, the CO2 adsorption properties of hydrotalcites are enhanced through the production of novel supported hybrids (carbon nanotubes and graphene oxide) and the promotion with alkali metals. Hydrogen is regarded as a sustainable energy carrier, since the end users produce no carbon emissions. However, given that most of the hydrogen produced worldwide comes from fossil fuels, its potential as a carbon-free alternative depends on the ability to capture the carbon dioxide released during manufacture. Sorption-enhanced hydrogen production, in which CO2 is removed as it is formed, can make a major contribution to achieving this. The challenge is to find solid adsorbents with sufficient CO2 capacity that can work in the right temperature window over repeated adsorption-desorption cycles. The book presents a highly detailed characterization of the materials, together with an accurate measurement of their adsorption properties under dry conditions and in the presence of steam. It demonstrates that even small quantities of graphene oxide provide superior thermal stability to hydrotalcites due to their compatible layered structure, making them well suited as volume-efficient adsorbents for CO2. Lastly, it identifies suitable catalysts for the overall sorption-enhanced water gas shift process.
Author: Gang Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 422
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Book Description
VSA (Vacuum Swing Adsorption) is a promising technology for capturing CO2 which is known to contribute to global warming. Capture of CO2 from flue gas streams using adsorption processes must deal with the prospect of high humidity streams containing bulk CO2 as well as other impurities such as SOx, NOx, etc. However, most studies to date have ignored this aspect of CO2 capture. The major problem caused by water vapour is that water is a much stronger adsorbate than CO2 on most of the polar adsorbents thus drastically reducing the CO2 adsorption capacity. Although the water problem may be tackled by adding a pretreatment drier before the CO2VSA unit, this will result in a large increase of capital and operational cost. Therefore, there is a strong economic motivation to integrate the drying and CO2 recovery in a single VSA process for commercialization of CO2VSA technology.The main purpose of this project is to study the influence of water vapour on the adsorption of CO2 both in the light of fundamentals of adsorption and in the application of post-combustion carbon capture by vacuum swing adsorption experimentally and theoretically. Adsorption equilibria of a CO2/H2O binary mixture were measured on activated alumina F-200 at several temperatures and over a wide range of concentrations from 4% to around 90% relative humidity. In comparison with the single component data, the loading of CO2 was not reduced in the presence of H2O whereas at low relative humidity the adsorption of H2O was depressed. The binary system was described by a competitive/cooperative adsorption model where the readily adsorbed water layers acted as secondary sites for further CO2 adsorption via hydrogen bonding or hydration reactions. The combination of kinetic models namely a Langmuir isotherm for characterizing pure CO2 adsorption and a BET isotherm for H2O was extended to derive a binary adsorption equilibrium model for the CO2/H2O mixture. Models based on the ideal adsorbed solution theory of Myers and Prausnitz failed to characterize the data over the whole composition range and a large deviation of binary CO2/H2O equilibrium from ideal solution behavior was observed. The extended Langmuir-BET (LBET) isotherm, analogous to the extended Langmuir equation, drastically underestimated the CO2 loading. By incorporating the interactions between CO2 and H2O molecules on the adsorbent surface and taking into account the effect of nonideality, the realistic interactive LBET (R-LBET) model was found to be in very good agreement with the experimental data. In contrast, CO2 adsorption on zeolite 13X was entirely depressed at higher water humidity. Direct modification of 13X by silanes increased the hydrophobicity of the adsorbent but also reduced CO2 uptake.A laboratory-scale VSA apparatus was constructed and used to experimentally examine the capture of CO2 from a 10-12% synthetic flue gas stream over a range of water relative humidity. Breakthrough experiments with a binary CO2/H2O mixture in a near-adiabatic double layered 3A/13X column showed a peculiar dual roll-up phenomenon. Water adsorption generated a pure thermal wave which traveled ahead of the water concentration front and swept off the readily adsorbed CO2 leading to a thermal induced roll-up; the slow propagation of the water concentration wave displaced the CO2 by competitive adsorption resulting in n equilibrium induced roll-up. Cyclic VSA experiments with single layered 13X column and multilayered Al2O3/13X column configurations were conducted. The migration of the water and its subsequent impact on capture performance was evaluated. The formation of a water zone creates a "cold spot" which has implications for the system performance. Although the concentration of water leaving the bed under vacuum was high, the low vacuum pressure prevented condensation of this stream. The vacuum pump acted as a condenser and separator to remove bulk water. An important consequence of the presence of a water zone was to elevate the vacuum level thereby reducing CO2 working capacity. On the other hand, the internal purge of CO2 was found to be of critical importance to lower the water partial pressure during evacuation. The penetration of water in the column could be managed by keeping an appropriate volumetric purge-to-feed ratio or a higher vacuum level. This effect was predicted by our axial adiabatic working capacity model. At relatively high water content (> 4% v/v) in the feed, the use of a water prelayer was essential to prevent failure of the system. The overall performance of the VSA with wet feed decreased slightly compared with the performance for dry feed. Reasonable results have been achieved for a triple layered single column VSA in the case with the highest feed humidity of 8.5% v/v, with a product CO2 recovery of 58.2%, purity 52.4% and productivity 0.128 kg CO2/h/L adsorbent. Further scale-up of this process by using multi-columns and a more sophisticated cycle design is expected to further improve the performance. Thus although there is a detrimental effect of water on CO2 capture, long term recovery of CO2 is still possible in a single VSA process.
