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Author: Stephanie Anne Freeman Publisher: ISBN: Category : Languages : en Pages : 1468
Book Description
Absorption-stripping with aqueous, concentrated piperazine (PZ) is a viable retrofit technology for post-combustion CO2 capture from coal-fired power plants. The rate of thermal degradation and oxidation of PZ was investigated over a range of temperature, CO2 loading, and PZ concentration. At 135 to 175 °C, degradation is first order in PZ with an activation energy of 183.5 kJ/mole. At 150 °C, the first order rate constant, k1, for thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity is 6.12 x 10−9 s−1. After 20 weeks of degradation at 165 °C, 74% and 63%, respectively, of the nitrogen and carbon lost in the form of PZ and CO2 was recovered in quantifiable degradation products. N-formylpiperazine, ammonium, and N-(2-aminoethyl) piperazine account for 57% and 45% of nitrogen and carbon lost, respectively. Thermal degradation of PZ likely proceeds through SN2 substitution reactions. In the suspected first step of the mechanism, 1-[2-[(2-aminoethyl) amino]ethyl] PZ is formed from a ring opening SN2 reaction of PZ with HPZ. Formate was found to be generated during thermal degradation from CO2 or CO2-containing molecules. An analysis of k1 values was applied to a variety of amines screened for thermal stability in order to predict a maximum recommended stripper temperature. Morpholine, piperidine, PZ, and PZ derivatives were found to be the most stable with an allowable stripper temperature above 160 °C. Long-chain alkyl amines or alkanolamines such as N-(2-hydroxyethyl)ethylenediamine and diethanolamine were found to be the most unstable with an allowable stripper temperature below 120 °C. Iron (Fe2) and stainless steel metals (Fe2+, Ni2+, and Cr3+) were found to be only weak catalysts for oxidation of PZ, while oxidation was rapidly catalyzed by copper (Cu2+). In a system with Fe2+ or SSM, 5 kPa O2 in the inlet flue gas, a 55 °C absorber, and one-third residence time with O2, the maximum loss rate of PZ is expected to 0.23 mol PZ/kg solvent in one year of operation. Under the same conditions but with Cu2+ present, the loss rate of PZ is predicted to be 1.23 mole PZ/kg solvent in one year of operation. Inhibitor A was found to be effective at decreasing PZ loss catalyzed by Cu2+. Ethylenediamine, carboxylate ions, and amides were the only identified oxidation products. Total organic carbon analysis and overall mass balances indicate a large concentration of unidentified oxidation products.
Author: Stephanie Anne Freeman Publisher: ISBN: Category : Languages : en Pages : 1468
Book Description
Absorption-stripping with aqueous, concentrated piperazine (PZ) is a viable retrofit technology for post-combustion CO2 capture from coal-fired power plants. The rate of thermal degradation and oxidation of PZ was investigated over a range of temperature, CO2 loading, and PZ concentration. At 135 to 175 °C, degradation is first order in PZ with an activation energy of 183.5 kJ/mole. At 150 °C, the first order rate constant, k1, for thermal degradation of 8 m PZ with 0.3 mol CO2/mol alkalinity is 6.12 x 10−9 s−1. After 20 weeks of degradation at 165 °C, 74% and 63%, respectively, of the nitrogen and carbon lost in the form of PZ and CO2 was recovered in quantifiable degradation products. N-formylpiperazine, ammonium, and N-(2-aminoethyl) piperazine account for 57% and 45% of nitrogen and carbon lost, respectively. Thermal degradation of PZ likely proceeds through SN2 substitution reactions. In the suspected first step of the mechanism, 1-[2-[(2-aminoethyl) amino]ethyl] PZ is formed from a ring opening SN2 reaction of PZ with HPZ. Formate was found to be generated during thermal degradation from CO2 or CO2-containing molecules. An analysis of k1 values was applied to a variety of amines screened for thermal stability in order to predict a maximum recommended stripper temperature. Morpholine, piperidine, PZ, and PZ derivatives were found to be the most stable with an allowable stripper temperature above 160 °C. Long-chain alkyl amines or alkanolamines such as N-(2-hydroxyethyl)ethylenediamine and diethanolamine were found to be the most unstable with an allowable stripper temperature below 120 °C. Iron (Fe2) and stainless steel metals (Fe2+, Ni2+, and Cr3+) were found to be only weak catalysts for oxidation of PZ, while oxidation was rapidly catalyzed by copper (Cu2+). In a system with Fe2+ or SSM, 5 kPa O2 in the inlet flue gas, a 55 °C absorber, and one-third residence time with O2, the maximum loss rate of PZ is expected to 0.23 mol PZ/kg solvent in one year of operation. Under the same conditions but with Cu2+ present, the loss rate of PZ is predicted to be 1.23 mole PZ/kg solvent in one year of operation. Inhibitor A was found to be effective at decreasing PZ loss catalyzed by Cu2+. Ethylenediamine, carboxylate ions, and amides were the only identified oxidation products. Total organic carbon analysis and overall mass balances indicate a large concentration of unidentified oxidation products.
Author: Yuying Wu (Ph. D.) Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Piperazine is a promising second-generation solvent for amine scrubbing in post-combustion CO2 capture. However, the oxidative degradation of PZ can cause environmental problems and economic loss. This work presents the effects of two mitigation methods: carbon treating and N2 sparging, on the PZ oxidation in long-term operations. The species and their respective quantities adsorbed by the activated carbon were tested in a bench-scale device. The carbon was then tested in the High Temperature Oxidation Reactor (HTOR), where the solvent oxidizes at a reasonably fast rate. Pilot plant campaigns were also performed at the UT Austin SRP and the National Carbon Capture Center (NCCC) and the effects were verified. When dissolved Fe is removed by carbon treating or other methods, available soluble Fe in the system dissolves and replaces the dissolved Fe. Therefore, all available Fe and ligands need to be removed for the mitigation to be effective. The sources of soluble Fe include fly ash and the corrosion of stainless steel, and the ligands are degradation products. All PZ degraded solvents have two absorbance peaks at 320 nm and 538 nm. The 320 nm peak is caused by dissolved metals, especially Fe, complexed by degradation products. The 320 nm peak is related to the amine degradation level and can be used as a simple and efficient method to estimate the amine degradation rate. The pilot plant data suggest that NO2 can oxidize PZ significantly, possibly through radical reactions. 0.01 mmol/kg-hr absorption of NO2 increased the PZ oxidation rate from 1.2 mmol/kg-hr to 2.5 mmol/kg-hr
Author: Athanasios I. Papadopoulos Publisher: John Wiley & Sons ISBN: 1119106443 Category : Science Languages : en Pages : 686
Book Description
This comprehensive volume brings together an extensive collection of systematic computer-aided tools and methods developed in recent years for CO2 capture applications, and presents a structured and organized account of works from internationally acknowledged scientists and engineers, through: Modeling of materials and processes based on chemical and physical principles Design of materials and processes based on systematic optimization methods Utilization of advanced control and integration methods in process and plant-wide operations The tools and methods described are illustrated through case studies on materials such as solvents, adsorbents, and membranes, and on processes such as absorption / desorption, pressure and vacuum swing adsorption, membranes, oxycombustion, solid looping, etc. Process Systems and Materials for CO2 Capture: Modelling, Design, Control and Integration should become the essential introductory resource for researchers and industrial practitioners in the field of CO2 capture technology who wish to explore developments in computer-aided tools and methods. In addition, it aims to introduce CO2 capture technologies to process systems engineers working in the development of general computational tools and methods by highlighting opportunities for new developments to address the needs and challenges in CO2 capture technologies.
Author: Helei Liu Publisher: Springer ISBN: 303000922X Category : Technology & Engineering Languages : en Pages : 55
Book Description
This book presents a comprehensive review of the latest information on all aspects of the post-combustion carbon capture process. It provides designers and operators of amine solvent-based CO2 capture plants with an in-depth understanding of the most up-to-date fundamental chemistry and physics of the CO2 absorption technologies using amine-based reactive solvents. Topics covered include the physical properties, chemical analysis, reaction kinetics, CO2 solubility, and innovative configurations of absorption and stripping columns as well as information on technology applications. This book also examines the post-build operational issues of corrosion prevention and control, solvent management, solvent stability, solvent recycling and reclaiming, intelligent monitoring and plant control including process automation. In addition, the authors discuss the recent insights into the theoretical basis of plant operation in terms of thermodynamics, transport phenomena, chemical reaction kinetics/engineering, interfacial phenomena, and materials. The insights provided help engineers, scientists, and decision makers working in academia, industry and government gain a better understanding of post-combustion carbon capture technologies.
Author: Mohammad Reza Rahimpour Publisher: Elsevier ISBN: 0443192340 Category : Technology & Engineering Languages : en Pages : 581
Book Description
Advances and Technology Development in Greenhouse Gases: Emission, Capture and Conversion is a comprehensive seven-volume set of books that discusses the composition and properties of greenhouse gases, and introduces different sources of greenhouse gases emission and the relation between greenhouse gases and global warming. The comprehensive and detailed presentation of common technologies as well as novel research related to all aspects of greenhouse gases makes this work an indispensable encyclopedic resource for researchers in academia and industry.Volume 4 titled Carbon Capture Technologies is devoted to efficient technologies utilized for separation that are the heart of controlling carbon-made greenhouse gases (GHGs). The book starts with a review of carbon capture concepts with a focus on energy penalties as well as the operating pilots and plants followed by a meticulous investigation of different classes of capture methods. Section 2 surveys the absorption process including amines, physical absorbents, alkaline solvents, ionic liquids and deep eutectic solvents, nanoparticle-enhanced solvents, as well as a number of novel materials and structures, that are employed to eliminate GHGs utilizing absorption. Section 3 addresses adsorption-based strategies with a focus on the role of different solid adsorbents, introduces technologies that benefit from membranes, and considers different materials utilized in the fabrication of membranes. The final section deals with other as state-of-the-art alternatives in carbon capture. Moreover, each section reviews the economic assessments and environmental challenges. - Introduces carbon capture concepts and challenges - Describes various absorption and adsorption processes for carbon capture - Includes various membrane technologies for carbon capture
Author: Alexander Karl Voice Publisher: ISBN: Category : Languages : en Pages : 658
Book Description
Amine degradation in aqueous amine scrubbing systems for capturing CO2 from coal fired power plants is a major problem. Oxygen in the flue gas is the major cause of solvent deterioration, which increases the cost of CO2 capture due to reduced capacity, reduced rates, increased corrosion, solvent makeup, foaming, and reclaiming. Degradation also produces environmentally hazardous materials: ammonia, amides, aldehydes, nitramines, and nitrosamines. Thus it is important to understand and mitigate amine oxidation in industrial CO2 capture systems. A series of lab-scale experiments was conducted to better understand the causes of and solutions to amine oxidation. This work included determination of rates, products, catalysts, and inhibitors for various amines at various conditions. Special attention was paid to understanding monoethanolamine (MEA) oxidation, whereas oxidation of piperazine (PZ) and other amines was less thorough. The most important scientific contribution of this work has been to show that amine oxidation in real CO2 capture systems is much more complex than previously believed, and cannot be explained by mass transfer or reaction kinetics in the absorber by itself, or by dissolved oxygen kinetics in the cross exchanger. An accurate representation of MEA oxidation in real systems must take into account catalysts present (especially Mn and Fe), enhanced oxygen mass transfer in the absorber as a function of various process conditions, and possibly oxygen carriers other than dissolved oxygen in the cross exchanger and stripper. Strategies for mitigating oxidative degradation at low temperature, proposed in this and previous work are less effective or ineffective with high temperature cycling, which is more representative of real systems. In order of effectiveness, these strategies are: selecting an amine resistant to oxidation, reduction of dissolved metals in the system, reduction of the stripper temperature, reduction of the absorber temperature, and addition of a chemical inhibitor to the system. Intercooling in the absorber can reduce amine oxidation and improve energy efficiency, whereas amine oxidation should be considered in choosing the optimal stripper temperature. In real systems, 2-amino-2-methyl-1-propanol (AMP) is expected to be the most resistant to oxidation, followed by PZ and PZ derivatives, then methyldiethanolamine (MDEA), and then MEA. MEA oxidation with high temperature cycling is increased 70% by raising the cycling temperature from 100 to 120 °C, the proposed operational temperature range of the stripper. PZ oxidation is increased 100% by cycling to 150 °C as opposed to 120 °C. Metals are expected to increase oxidation in MEA and PZ with high temperature cycling by 40 - 80%. Inhibitor A is not expected to be effective in real systems with MEA or with PZ. MDEA is also not effective as an inhibitor in MEA, and chelating agents diethylenetriamine penta (acetic acid) (DTPA) and 2,5-dimercapto-1,3,4-thiadiazole (DMcT) are only mildly effective in MEA. Although MEA oxidation in real systems cannot be significantly reduced by any known additives, it can be accurately monitored on a continuous basis by measuring ammonia production from the absorber. Ammonia production was shown to account for two-thirds of nitrogen in degraded MEA at low temperature and with high temperature cycling, suggesting that it is a reliable indicator of MEA oxidation under a variety of process conditions. A proposed system, which minimizes amine oxidation while maintaining excellent rate and thermodynamic properties for CO2 capture would involve use of 4 m AMP + 2 m PZ as a capture solvent with the stripper at 135 °C, intercooling in the absorber, and use of a corrosion inhibitor or continuous metals removal system. Reducing (anaerobic) conditions should be avoided to prevent excessive corrosion from occurring and minimize the amount of dissolved metals. This system is expected to reduce amine oxidation by 90-95% compared with the base case 7 m MEA with the stripper at 120 °C.
Author: Paul Feron Publisher: Woodhead Publishing ISBN: 0081005156 Category : Technology & Engineering Languages : en Pages : 816
Book Description
Absorption-Based Post-Combustion Capture of Carbon Dioxide provides a comprehensive and authoritative review of the use of absorbents for post-combustion capture of carbon dioxide. As fossil fuel-based power generation technologies are likely to remain key in the future, at least in the short- and medium-term, carbon capture and storage will be a critical greenhouse gas reduction technique. Post-combustion capture involves the removal of carbon dioxide from flue gases after fuel combustion, meaning that carbon dioxide can then be compressed and cooled to form a safely transportable liquid that can be stored underground. - Provides researchers in academia and industry with an authoritative overview of the amine-based methods for carbon dioxide capture from flue gases and related processes - Editors and contributors are well known experts in the field - Presents the first book on this specific topic
Author: Paul Thomas Nielsen (III) Publisher: ISBN: Category : Languages : en Pages : 580
Book Description
Solvent oxidation in amine scrubbing systems for post-combustion CO2 capture is a significant issue. Piperazine (PZ) is a promising solvent due to its relative stability and performance. PZ oxidation rates and products were thoroughly characterized in the High Temperature Oxidation Reactor (HTOR) bench-scale cyclic degradation apparatus and compared to observed PZ oxidation from campaigns at the UT Austin SRP, CSIRO Tarong, and “Pilot Plant 2” (PP2) pilot-scale facilities. The HTOR simulated solvent conditions cycling between a 40-55 °C absorber and a 120-150 °C stripper. In both the bench and pilot-scale the intermediary degradation products piperazinol, piperazinone, and ethylenediamine were initially the most significant degradation products before reaching steady-state concentrations, with ammonia and formate the most significant final products produced from the decomposition of the intermediates. PZ oxidation increased as the solvent degraded due to the cycling of dissolved iron, aldehydes, and hydroperoxide contaminants, which could be oxidized in the absorber and subsequently oxidize PZ at high temperature. An N2 sparger was used to selectively remove dissolved oxygen (DO) in the HTOR before heating while still allowing for oxidation due to contaminant cycling. Ammonia was correlated to dissolved iron at 0.72 mmol NH3/kg PZ/hr/(mmol/kg Fe) [superscript 0.5]. An additional 0.4 mmol NH3/kg/hr was produced due to direct reaction of PZ with DO regardless of the level of contamination. Dissolved iron was solubility-limited in both the HTOR and pilot plants, but increased as the solvent degraded, resulting in the autocatalytic effect of PZ oxidation. HTOR data was used to model oxidation and solvent management costs for a full-scale amine scrubber. The model matched observed oxidation at SRP and Tarong. Maintaining 0.1 to 0.5 wt % contaminant accumulation optimized amine make-up, solvent reclaiming, and increased energy costs due to changes in solvent viscosity, at a minimum of $2.6/MT CO2 for PZ treating coal flue gas with a thermal reclaimer to remove contaminants. Feed rate and amine recovery in the reclaimer were the most impactful design variables, followed by operating temperature and hold-up in the stripper, prescrubbing of flue gas contaminants SO2 and NO2, and least significantly N2 sparging to remove DO.
Author: Omkar Ashok Namjoshi Publisher: ISBN: Category : Languages : en Pages : 548
Book Description
The thermal degradation of piperazine (PZ)-promoted tertiary amine solvents for CO2-capture has been investigated and quantified in this study, which takes place in the high temperature (>100 °C) section of the capture plant. PZ-promoted tertiary amine solvents possess comparable energy performance to concentrated PZ, considered a benchmark solvent for CO2 capture from flue gas without its solid solubility limits that hinder operational performance. PZ-promoted aliphatic tertiary amine solvents with at least one methyl group, such as methyldiethanolamine (MDEA), were found to be the least stable solvents and can be regenerated in the desorber between 120 and 130 °C. PZ-promoted tertiary amine solvents with no methyl groups, such as ethyldiethanolamine (EDEA), were found to have an intermediate stability and can be regenerated in the desorber between 130 and 140 °C. PZ-promoted tertiary morpholines, such as hydroxyethylmorpholine (HEM), were found to be stable above 150 °C. Tertiary amines with at least one hydroxyethyl or hydroxyisopropyl functional group form intermediate byproducts that can accelerate the degradation rate of the promoter by a factor from 1.5 to 2.3. Tertiary amines with 3-carbon and 5-carbon functional groups, such as dimethylaminopropanol or dimethylaminoethoxyethanol, form stable intermediate byproducts that do not readily react with the promoter. A degradation model for PZ-promoted MDEA that can be used for process design calculations using acidified solvent degradation to model the initial degradation rate over a range of CO2 loading and initial amine concentration was developed. Thermal degradation was modeled using second-order kinetics as a function of free amine and protonated amine. The degradation kinetics, along with the observed degradation products, suggest that the dominant pathway is by free PZ attack on a methyl substituent group of protonated MDEA to form diethanolamine (DEA) and 1-methylpiperazine (1-MPZ). The model predicts total amine loss from experimental CO2 degradation rate measurements within 20%. The modeling work was extended to other PZ-promoted tertiary amine solvents with bulkier substituent groups. PZ attack on ethyl or hydroxyethyl groups was 17% and 4% as fast, respectively, as attack on methyl groups.
Author: Stephanie Anne Freeman
Author: Stephanie Anne Freeman
Author: Yuying Wu (Ph. D.)
Author: Athanasios I. Papadopoulos
Author: Helei Liu
Author: Mohammad Reza Rahimpour
Author: Alexander Karl Voice
Author: Paul Feron
Author: Nevil Vincent Sidgwick
Author: Paul Thomas Nielsen (III)
Author: Omkar Ashok Namjoshi