Search

Crystallization fouling in heat exchangers, subsurface energy production, and membrane technology remains a challenge. The reactive crystallization process is governed by whether growth or nucleation dominates the precipitation process. However, there is little direct experimental evidence on the fundamentals of nucleation and growth on surfaces over a wide range of supersaturations. We investigated the crystallization fouling of BaSO4at 10 different supersaturations (saturation ratios from 6.6 to 457.1). We show that deposition behavior changes from a growth-dominated regime to a nucleation-dominated regime as the supersaturation increases; these changes in the dominant regime affect the resilience of the surface deposits. At low supersaturations, crystals have a secondary order, which increases their surface resilience. At high supersaturations, where nucleation processes dominate, crystals aggregate on the surface with no discernible secondary structure. At a saturation ratio of 457, nucleation processes are accelerated, causing previously aggregated crystals to become isolated. Due to increased isolation, the crystal resilience decreases, and the crystals become more vulnerable to detaching from the surface. To characterize surface deposition, we introduced the sticking factor as a measure of the stickability. We present an analysis of the stickability of BaSO4, CaCO3, and CaSO4, based on published data, and observe mean sticking factors of 1.15%, 0.80%, and 0.11%, respectively.

Solid–liquid equilibrium (SLE) data were obtained at 0.1 MPa for binary, ternary, and quaternary aqueous solutions containing ammonia (NH3), ammonium bicarbonate (NH4HCO3), methyl diethanolamine (MDEA), and potassium carbonate (K2CO3) using a modified Beckmann apparatus. The reproducibility of the experimental method was verified by measuring the SLE of aqueous solutions containing NH3, K2CO3, or MDEA in a temperature range between 237 and 273 K. A total of 120 new data points were measured for MDEA–NH3and NH4HCO3–H2O mixtures (250 to 305 K), and 23 new data points were obtained for MDEA–K2CO3–H2O solutions (250 to 270 K). These measurements allow for an accurate estimation of water activity in such mixtures and provide insights on the limits of solid formation. The results indicate that the addition of MDEA increases the solubility of NH4HCO3, whereas a liquid–liquid split was observed when K2CO3was added to aqueous MDEA. This opens the possibility of using it as a phase demixing solvent for carbon capture. Despite the extensive literature regarding mixed salt–amine solutions, liquid demixing in such systems has not been reported before. For this reason, the binodal curve for the MDEA–K2CO3–H2O solution was measured at 293.15 K using the method of cloud point titration. These results assist the selection of operation parameters that avoid a liquid–liquid split in the process.

In this study, the physicochemical properties of an enzyme-activated biological solvent for carbon capture were experimentally measured. The solvent consists of an amino acid (l-lysine) mixed with carbonic anhydrase, a composition inspired from human respiration. Densities and viscosities of aqueous blends of carbonic anhydrase enzyme and l-lysine solutions have been measured using an Anton Paar DMA 4100 (capillary type) density meter and a Paar AMV 200 (rolling ball type) viscometer at atmospheric conditions, for a variety of temperatures (303.15–343.15 K) and solution concentrations. The results were compared to various conventional solvents used for carbon dioxide capture, which includes monoethanolamine (MEA), N-methyldiethanolamine (MDEA), and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4). The studied solvent has a slightly higher density than MEA and MDEA but is lower than BMIMBF4. In addition to that, our solvent has a slightly higher viscosity than MEA but lower than that of MDEA. This offers comparable performance in terms of mass transfer rates in the absorber, pumping costs, and heat transfer. The results were modeled by a semiempirical equation. The model can predict densities and viscosities for a range of solvent concentrations of l-lysine and carbonic anhydrase with high accuracy (AAD% of 0.06% for density and 2.86% for viscosity) and can satisfactorily predict density and viscosity values at other parametric conditions.

•An integrated simulation approach is applied to model CO2capture and heat pumps•A 2-stage heat pump system is utilized to electrify an MEA-based biogas upgrading process•Heat pump performance (COP) is investigated at varied stripper pressures•Heat pumps with vacuum operated stripper reduces energy consumption by up to 68 %•A techno-economic analysis shows a levelized cost reduction of up to 33 % .

Post-combustion capture is a promising technology for developing CO2neutral power plants. However, to make it economically and technically feasible, capture plants must follow the fast and large load changes of the power plants without decreasing the overall performance of the plant. Dynamic modeling and simulation is therefore needed to evaluate the performance of this plant under critical operation.