A Novel Methodology for Online Analysis of Amine Solution Degradation Caused by Fly Ash

Freezing points for aqueous monoethanolamine (MEA), methyl diethanolamine (MDEA), and MEA−MDEA solutions were measured in the concentration range from 0 to 0.4 mass fractions of the alkanolamines. For the aqueous MEA−MDEA system, freezing points for 1:4, 1:2, 1:1, 2:1, and 4:1 molar ratios of MEA/MDEA were determined. The experimental values indicate that the MDEA−water interaction is stronger than the MEA−water interaction. Measurements were carried out by a new modified Beckmann apparatus, which has not previously been described. The apparatus and method proved to have good repeatability and accuracy. A correlation of the freezing points as functions of the solution composition was made. Measurements of aqueous MEA and aqueous MDEA were compared to experiments found in the open literature.

The products and pathway for the oxidative degradation of CO2-loaded and concentrated aqueous solution of monoethanolamine (MEA)/methyl diethanolamine (MDEA) mixture (i.e., MEA−MDEA−H2O−CO2 system) were evaluated and compared with those for the MEA−H2O−CO2 system in a stirred cell reactor at temperatures in the range of 55−120 °C, overall amine concentration in the range of 5−9 mol/L, MDEA/MEA ratio of 0−0.4, CO2 loading in the range of 0−0.53 mol/mol of total amine, and O2 pressure of 250 kPa in order to determine the role of MDEA in preventing MEA degradation. The results showed that fewer degradation products were obtained for the MEA−H2O−O2 system for both the CO2-loaded and CO2-free cases as compared with the MEA−MDEA−H2O−O2 system. However, the addition of MDEA drastically reduced the extent of MEA degradation as well as the amount of nonenvironmentally benign degradation products. Our overall results indicate that, under our experimental conditions, MDEA is more prone to oxidative degradation and, ...

Energy efficient CO2 capture in dual functionalized ionic liquids and N-methyldiethanolamine solvent blend system at elevated pressures: Interaction mechanism and heat duties

Extended UNIQUAC model for thermodynamic modeling of CO 2 absorption in aqueous alkanolamine solutions

Diamine based hybrid-slurry system for carbon capture

The thermodynamic framework that was developed in a previous work [Vrachnos et al. Ind. Eng. Chem. Res. 2004, 43, 2798] for the description of chemical and vapor−liquid equilibria of carbon dioxide, hydrogen sulfide, and their mixtures in aqueous methyldiethanolamine (MDEA) solutions is revised and extended in this study to the absorption of carbon dioxide into aqueous monoethanolamine (MEA) solutions and aqueous MDEA−MEA blends. The results of the model are compared with experimental data taken from the literature. Very satisfactory predictions of acidic gas vapor−liquid equilibrium over MDEA, MEA, and their blends at various concentrations, acidic gas loadings, and temperatures are obtained.

The objective of this study was to measure the ternary diffusion coefficients of aqueous blended alkanolamine systems monoethanolamine (MEA) + N-methyldiethanolamine (MDEA) + water using the Taylor dispersion technique for temperatures 30 to 50 oC. The ternary diffusion coefficients are reported for solutions containing the total amine concentrations, 2, 3, and 4 kmol•m-3 for various amine concentration ratio. The corresponding mutual diffusion coefficients of aqueous MEA and aqueous MDEA solutions were also measured. In a Taylor experiment, a delta function of solution is injected into a laminar carrier stream of reference fluid which flows in a long capillary tube. The injected solutes spread out as they flow along the tube. The concentration profiles of dispersed solutes are determined by a differential refractometer. A regression procedure is used to calculate the ternary diffusion coefficients from the refractive index profiles. The main diffusion coefficients (D11 and D22) and the cross coefficients (D12 and D21) are reported as function of temperature and concentration of alkanolamines. The dependence of the diffusion coefficients on the compositions and the temperature were discussed. Based on the theoretical model, the calculations of the main diffusion coefficients (D11 and D22) and the cross coefficients (D12 and D21) from the activity and the partial molar volume of components were also reported. A fairly good result was obtained between the calculated and the measured values of ternary mutual diffusivity.

Fly ash consists of mainly silt-size spherules that form during high-temperature coal combustion, such as in steam locomotives and coal-burning power plants. In the eastern USA, fly ash was distributed across the landscape atmospherically beginning in the late 19th century, peaking in the mid-20th century, and decreasing sharply with implementation of late 20th century particulate pollution controls. Although atmospheric deposition is limited today, fly ash particles continue to be resedimented into alluvial and lacustrine deposits from upland soil erosion and failure of fly ash storage ponds. Magnetic fly ash is easily extracted and identified microscopically, allowing for a simple and reproducible method for identifying post-1850 CE (Common Era) alluvium and lacustrine sediment. In the North Carolina Piedmont, magnetic fly ash was identified within the upper 50 cm at each of eight alluvial sites and one former milldam site. Extracted fly ash spherules have a magnetite or maghemite composition, with substitutions of Al, Si, Ca, and Ti, and range from 3–125 µm in diameter (mainly 10–45 µm). Based on the presence of fly ash, post-1850 alluvial deposits are 15–45 cm thick in central North Carolina river valleys (<0.5 km wide), ~60% thinner than in central Illinois valleys of similar width. Slower sedimentation rates in North Carolina watersheds are likely a result of a less agricultural land and less erodible (more clayey) soils. Artificial reservoirs (Lake Decatur, IL) and milldams (Betty’s Mill, NC), provide chronological tests for the fly ash method and high-resolution records of anthropogenic change. In cores of Lake Decatur sediments, changes in fly ash content appear related to decadal-scale variations in annual rainfall (and runoff), calcite precipitation, land-use changes, and/or lake history, superimposed on longer-term trends in particulate pollution.

Modeling H2S solubility in aqueous MDEA, MEA and DEA solutions by the electrolyte SRK-CPA EOS

A physicochemical model developed in earlier work for representing H 2 S and CO 2 solubility in aqueous solutions of monoethanolamine (MEA) and diethanolamine (DEA) was extended to include the mixtures of methyldiethanolamine (MDEA) with MEA or DEA. Activity coefficients are represented with the electrolyte-NRTL equation treating both long(range electrostatic interactions and short-range binary interactions. Adjustable binary interaction parameters of the model were fitted on binary and ternary system MDEA data reported in the literature. The solubility of CO 2 in aqueous mixtures of MDEA with MEA or DEA was measured at 40 and 80 o C over a wide range of CO 2 partial pressures. Representation of the data by the model is good, especially at low to moderate acid gas loadings

Heterogeneous oxidation of mercury in simulated post combustion conditions

98/00335 Method for preparing fly ash for high compressive strength concrete and mortar, and compositions thereof

Effects of post-mercury-control fly ash on fresh and hardened concrete properties

The increase in atmospheric CO2 caused by human activities has driven the development of technologies to capture this gas before it reaches the atmosphere. This study analyzed CO2 sorption using amine-based solvents, such as methyldiethanolamine (MDEA), diethylenetriamine (DETA), triethanolamine (TEA), and monoethanolamine (MEA) in 40 wt.% aqueous solutions, under high-pressure conditions (initial pressure: 500 psia) and room temperature (30 °C), in both non-stirred and stirred systems. Piperazine (PZ), a heterocyclic compound, was tested as an additive to improve the kinetics of the CO2 sorption process. Kinetic and thermodynamic analyses were conducted to evaluate the efficiency of each amine-based solution in terms of reaction rate and CO2 loading capacity. MEA and TEA exhibited higher reaction rates, while DETA and MDEA were the most thermodynamically efficient due to the highest CO2 loading capacity. The PZ kinetic behavior depended on the equipment used; in the non-stirred system, no kinetic effect was observed, while in the stirred system, this effect was appreciable. Additionally, a corrosivity study revealed that MEA, a primary amine, was the most corrosive, whereas TEA, a tertiary amine, was the least corrosive.

Ethanolamines have traditionally been used for capturing CO2 in a post-combustion carbon capture column. However, the use of ethanolamines, due to their high volatility and solvent losses, is not sustainable. One of the ways in which the solvent loss occurs is in the form of aerosols from the top of the column. The mechanism, rate of nucleation, growth rate, and interaction leading to the formation of aerosols, although essential for better process design, remain obscure. Using molecular dynamics simulations, we herein, analyze the formation of aerosols in columns based on aqueous monoethanolamine (MEA), aqueous methyldiethanolamine (MDEA), and their mixtures, using reference, pilot-scale, and industrial-scale data. In particular, the nucleation rate and cluster growth analyses were performed for five different cases. The results show that CO2 concentration had a strong influence on the rate of aerosol formation, a factor that can be easily controlled for better process design. Moreover, the interactions within the formed aerosols were mainly dominated by CO2–water interactions. Taken together, our results and analysis contribute toward a better understanding of aerosol formation and present some practical value, namely, calculated nucleation rates and particulate growth rates can be used in process simulators to account for solvent losses, factors that were identified as contributing to formation of particulate matter can be controlled and adjusted in design process simulations and in real plants, providing better performance of post-combustion carbon capture columns and thus suggest ways to prevent solvent loss.