Author: Ching-Ting Liu Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Current obstacles that prevent commercial implementation of amine-scrubbing CO2 capture are the high costs. Reducing capital costs by appropriate selection of construction materials, which requires knowledge of material corrosion performance for the process, will improve the economic feasibility of this technology. Corrosion was evaluated in three pilot plant campaigns using aqueous piperazine with the Advanced Stripper (PZAS). 316L stainless steel (SS) experienced higher corrosion than 304 SS and 2205 duplex SS, and the corrosion rate showed strong dependence on the temperature. 304 and 2205 performed well at all locations and should be good construction materials for PZAS. Degraded PZ exacerbated 316L corrosion, and removal of PZ degradation products using a carbon adsorption bed significantly reduced corrosion. Carbon steel (CS) corrosion showed a weak temperature effect because the corrosion was more dependent on the protective siderite film. The protectiveness of the films was related to fluid velocity. Ni-based alloys corroded in PZ, and the rate increased with temperature. Corrosion of C1010 CS and SS (304, 316L, 430) was measured at absorber and water wash conditions on the bench-scale. Corrosion rate decreases with increasing PZ. With more than 0.003 m PZ in solution, CS has acceptable corrosion performance. Corrosion of CS increases with increasing partial pressure of CO2, suggesting loading is another dominant parameter for carbon steel corrosion. Temperature has a less significant effect than PZ concentration and loading. CS corrosion increases with increasing flow velocity at both absorber and water wash conditions. SS had little corrosion at this lower temperature. Performance of siderite (FeCO3) protective films on CS was studied at representative stripper conditions on the bench-scale. Siderite films can deposit on the surface of CS in CO2-loaded PZ solution at temperatures >100 °C and protect CS from corrosion. The protection may fail in degraded PZ. Ethylenediamine (EDA) is one of the major contributors for the loss of film protectiveness or can be the surrogate for the effect of PZ degradation on siderite film protection. A link between protectiveness and the apparent density of siderite films was discovered. The apparent density of siderite films decreases with increasing flow velocity and decreasing CO2 loading, resulting in higher corrosion of CS
Author: Kent Billington Fischer Publisher: ISBN: Category : Languages : en Pages : 448
Book Description
Post-combustion carbon capture and storage with amine absorbents is a key technology needed to provide low-cost decarbonized electricity. Improving understanding of corrosion by amines may reveal a solvent system compatible with carbon steel, which would reduce plant capital costs. Corrosion of stainless and carbon steel in aqueous monoethanolamine (MEA) and piperazine (PZ) has been measured. High temperature amine corrosion was measured in a bench-scale pressure vessel and iron solubility in amines was screened in stirred reactors. Corrosion was measured at two PZ pilot plants and one MEA pilot plant, using coupons and electrical resistance probes. Corrosion products were characterized by SEM and powder X-ray diffraction. Carbon steel (C1010) often performs well in 5 molal PZ up to 150 °C due to the formation of a passivating FeCO3 layer. This layer is promoted at high temperature, high CO2 loading, low solution velocity, and in amines with low Fe2+ solubility. FeCO3 formation is favorable at high temperature because Fe2+ solubility decreases and the kinetics of FeCO3 formation are faster. This also means that FeCO3 is not observed at low temperature. Despite this, carbon steel performs well at low temperature due to slower kinetics of metal oxidation. Depassivation and high corrosion of stainless steel (316L) can occur in amine solutions at high temperature (150 °C) when conditions are relatively anoxic and reducing. Performance of stainless at high temperature in PZ suggests that it can be pushed into and out of the passive state by small process changes, such as different flue gas O2 concentrations. However, stainless performs well in both MEA and PZ in pilot plants at ≈120 °C. Fe3+ corrosion products are generated in the absorber, then reduced to Fe2+ in the high temperature, anoxic conditions of the stripper. In this way, carried-over Fe3+ is responsible for oxidation of amine and corrosion at high temperature. Certain highly corrosive amines also have high Fe2+ solubility. Ethylamines like MEA are likely the correct chain length to form stable complexes with Fe2+ in solution. Stable Fe2+-amine complexes cause high Fe2+ solubility, which prevents FeCO3 formation and leads to high corrosion
Author: Manjula Nainar Publisher: ISBN: Category : Amines Languages : en Pages : 312
Book Description
This work explores the promise of aqueous solutions of blended monoethanolamine (MEA) and piperazine (PZ) as a cost-effective solvent for carbon dioxide (CO2) capture from industrial flue gas streams with respect to addressing corrosion, which is regarded as one of the most severe operational problems in typical CO2 capture plants. Two types of corrosion experiments were carried out in bench-scale setups, electrochemical tests for short-term exposure and weight loss tests for long-term exposure. The results show that the blended MEA/PZ solutions are more corrosive than the MEA solutions. The corrosion rate of carbon steel increases with concentration of PZ, total amine concentration, CO2 loading of solution, solution temperature, the presence of heat stable salts, and the presence of the proprietary oxidative degradation inhibitor (Inhibitor A provided by the University of Texas at Austin). Among the tested heat-stable salts, formate is the most corrosive salt, followed by acetate, oxalate, and thiosulfate in the absence of oxygen (O2), while acetate is the most corrosive salt followed by formate, oxalate, and thiosulfate in the presence of O2. Based on the level of corrosion rate found in the MEA/PZ system, corrosion control is required during plant operation to suppress the corrosion rate of carbon steel to below an acceptable level. Sodium metavanadate (NaVO3) and copper carbonate (CuCO3) were proven to be effective corrosion inhibitors with inhibition performance of up to 94-98%. Dissolved O2 is required in the solution to maintain active Cu2 or V5+, which, thus, prevents the metallic copper (Cu) from plating out or the formation of other oxidative states of vanadate. The performance of these two inhibitors can be deteriorated by the presence of heat-stable salts in the solutions.
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: 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: Immanuelraj Soosaiprakasam Publisher: ISBN: Category : Carbon dioxide mitigation Languages : en Pages : 292
Book Description
Corrosion is one of the most severe operational problems in CO2 absorption processes, which use aqueous solutions of alkanolamines, especially when carbon steel is used for plant construction. Corrosion inhibitors are widely applied used in this process to suppress severe corrosion to an acceptable level. However, currently available corrosion inhibitors are heavy metals, which are toxic to human health and the environment, making solvent handling and waste disposal more difficult and costly. This work evaluated a low-toxic corrosion inhibitor, copper carbonate (CuCO3), as a replacement for toxic corrosion inhibitors. An inhibition evaluation was performed on copper carbonate by examining its parametric effects on the corrosion rate and corrosion behavior of carbon steel.
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: Ching-Ting Liu
Author: Kent Billington Fischer
Author: Manjula Nainar
Author: Helei Liu
Author: Prakashpathi Gunasekaran
Author: Stephanie Anne Freeman
Author: Ameerudeen Najumudeen
Author: Donald E. Tackett
Author: Immanuelraj Soosaiprakasam
Author: Yuying Wu (Ph. D.)