Dual-Function Synergists Based on Glucose and Sucrose for Gas Hydrate and Corrosion Inhibition

© The increasing demand in the modern world for energy resources leads to the recovery of oil and gas fields in remote northern and Arctic regions. The development of additives that effectively prevent complications such as gas hydrate formation and corrosion is a relevant issue. In this work, a method for the modification of simple carbohydrates was proposed, which allows one to obtain reagents that are effective both in hydrate inhibition (in the form of synergistic additives to commercial hydrate inhibitors) and prevention of corrosion. Modification of glucose and sucrose was carried out by incorporation of two sulfonate and carboxyl groups into their structures. Synergists were used as bisodium salts. PVCap-based inhibitors (Luvicap EG and Luvicap 55W) were utilized as commercial kinetic hydrate inhibitors. This study has revealed that mixtures of the proposed reagents with PVCap-based polymers showed a significant synergistic effect. The temperature of hydrate onset decreased by 3.5 °C with the addition of 0.1 wt % of synergist to 0.5 wt % of PVCap-based KHI. Moreover, these reagents also effectively inhibited the corrosion of pipeline steel in 2 M HCl solution. Thus, the proposed synergists will reduce the harmful effects on the environment, risks of accidents, and operating costs due to their biocompatibility and gas hydrate and corrosion inhibition

Porous Alginate Scaffolds Designed by Calcium Carbonate Leaching Technique

One of the main challenges in modern tissue engineering is to design biocompatible scaffolds with finely tuned porous architecture and capacity to load bioactive molecules that guide the growth and differentiation of the cells during tissue reconstruction. This work proposes a strategy to design porous alginate scaffolds (PAS) with well-tuned architecture by leaching of sacrificial vaterite CaCO3 microspheres packed in alginate. Pore size and interconnectivity depend on CaCO3 sphere dimensions and packing as well as alginate concentration. Varying of these parameters, almost hundred percent pore interconnectivity (or, by contrast, a zero pore interconnectivity) can be achieved. Junctions between interconnected pores are about 50–70% of the pore dimensions that provides molecular transport through the PASs potentially ensuring diffusion of nutrition, oxygen and metabolic products when cell seeding. An opportunity to fabricate a multifunctional scaffold is demonstrated by encapsulation of desired macromolecules into the individual pores of a scaffold (is illustrated by dextran loading). Mechanical properties of PASs are found typical for soft and hydrated structures (Young's modulus of 19 ± 15 kPa) which is appropriate for cell seeding. The three cell lines (HeLa, HEK293, and L929) are cultured on different alginate scaffolds to examine cell viability and adhesiveness

Gas hydrate nucleation and growth in the presence of water-soluble polymer, nonionic surfactants, and their mixtures

© 2020 Elsevier B.V. We investigated the effect of mixtures of commercial nonionic surfactants Sintanol ALM-7 (A7), Sintanol ALM-10 (A10), Surfynol 465 (S6), Surfynol 485 (S8), and well-known kinetic hydrate inhibitor Luvicap 55W (sample P) on nucleation and growth of sII gas hydrate. The ramp method (cooling at a constant rate of 1 °C × h−1) was employed to determine hydrate onset temperature and subcooling of individual and mixed samples. The dosage of reagents varied within 0.25–1.0 mass% range. A7 and A10 were tested at concentrations of 1.6∙10−4–2.5∙10−3 mass% (about or lower than CMC) as well. All surfactants were found to be weak antinucleators of gas hydrates. The inhibition performance of the surfactants was significantly lower in comparison with Luvicap 55W. We observed that ethoxylated fatty alcohols (A7 and A10) at low concentrations demonstrated a hydrate-inhibiting action at nucleation and growth stages. The Luvicap 55W – surfactant mixtures were tested as KHIs with a total dosage of 0.5 mass%, and in the ratio of 1:1, 1:2, and 1:5. Several mixed samples (1:1 P + A10), (1:2 P + A10), (1:2 P + S6) have demonstrated the same or higher efficacy in inhibition of hydrate nucleation than pure KHI. The results obtained indicate the presence of a synergistic effect of kinetic inhibition of gas hydrate with mixtures of the polymer and ethoxylated nonionic surfactants. Among the mixtures, the best results were obtained for the sample (1:2 P + S6). Surfynol 465 is characterized by high solubility in water, low foaming (compared to other surfactants), and lower cost than vinyl lactam-based KHI. Thus, the Surfynol 465 is a promising synergist for the vinyl lactam polymeric KHI and allows reducing the dosage of the expensive polymer

Phase Change Materials in Energy: Current State of Research and Potential Applications

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. Recent research on phase change materials promising to reduce energy losses in industrial and domestic heating/air-conditioning systems is reviewed. In particular, the challenges q fphase change material applications such as an encapsulation strategy for active ingredients, the stability of the obtained phase change materials, and emerging corrosion complications are discussed. Moreover, phase change materials could be employed in refrigerators to increase the efficiency and in storage facilities to reduce evaporative losses of fuels and industrial liquid products. Promising areas for using these materials are highlighted. Ways of solving possible problems are outlined

The pursuit of a more powerful thermodynamic hydrate inhibitor than methanol. Dimethyl sulfoxide as a case study

Search for new, more effective hydrate formation inhibitors is one of the oil and gas industry's urgent tasks. Dimethyl sulfoxide (DMSO) can be considered as a promising anti-hydrate reagent. DMSO and its aqueous solutions were characterized by several physicochemical methods, including measuring their density, viscosity, freezing point, the methane hydrate equilibrium conditions (V-Lw-H), and identification of the hydrate type formed. The hydrate phase equilibria in the system of DMSO aqueous solution–gaseous methane were determined for a wide range of DMSO concentrations (0–55 mass%), temperatures (242–289 K), and pressures (3–13 MPa). X-ray measurements reveal that DMSO does not form double hydrate with methane over the entire concentration range. The data obtained show that DMSO is a thermodynamic hydrate inhibitor. To quantitatively describe the anti-hydrate activity of DMSO, a correlation of thermodynamic depression ΔTh with the mass fraction of DMSO in solution and gas pressure was proposed. It was found that at concentrations above 33 and 53 mass% DMSO becomes more effective THI than the widely used monoethylene glycol and methanol, respectively. Such behavior is associated with the greater non-ideality of DMSO aqueous solutions (negative deviations from Raoult's law) compared to alcohols aqueous solutions. A linear correlation linking the depression of hydrate equilibrium temperature ΔTh and ice freezing point ΔTice was also derived. A comparative analysis of the density and kinematic viscosity of aqueous solutions of DMSO and methanol (0–100 mass%) was performed. It was revealed that DMSO is a promising inhibitor combining high anti-hydrate activity, low volatility (compared to methanol), and acceptable viscosity properties of aqueous solutions

Gas Hydrate and Corrosion Inhibition Performance of the Newly Synthesized Polyurethanes: Potential Dual Function Inhibitors

Gas hydrate plugging and corrosion are two major flow assurance problems in oil and gas transmission pipelines. Since an incompatibility problem can occur during the simultaneous injection of gas hydrate and corrosion inhibitors, efficient dual function inhibitors would be an advantage. This study reports several newly synthesized waterborne polyurethanes (WPUs) that have a high potential as both corrosion inhibitors and gas hydrate kinetic ones. The length of the side substituents in different parts of the polymer and the ratio of polyethylene glycol (PEG) 400/1,2-butanediol were varied. The hydrate inhibition ability of WPUs was assessed using sapphire rocking cells (RCS6); weight loss, open circuit potential, and potentiodynamic polarization tests were employed to estimate their anti-corrosion activity. It was revealed that butyl derivatives (ethyl-butyl and methyl-butyl combinations) showed slightly better inhibition performance than commercial hydrate inhibitor poly(N-vinyl caprolactam) at 0.25 wt %, while partial replacement of PEG 400 with 1,2-butanediol reduced the inhibition activity. The gravimetric and electrochemical measurements confirmed that WPUs can suppress significantly the mild steel corrosion in both distilled and oilfield produced water saturated with CO2. Almost complete corrosion inhibition (96% and 98%) was achieved with 0.25 wt % of ethyl-butyl and methyl-butyl derivatives (without 1,2-butanediol), respectively. These findings indicate that WPUs can be considered as potential dual function reagents for inhibiting the gas hydrate formation and mild steel corrosion in CO2 saturated environments

Performance of Waterborne Polyurethanes in Inhibition of Gas Hydrate Formation and Corrosion: Influence of Hydrophobic Fragments

The design of new dual-function inhibitors simultaneously preventing hydrate formation and corrosion is a relevant issue for the oil and gas industry. The structure-property relationship for a promising class of hybrid inhibitors based on waterborne polyurethanes (WPU) was studied in this work. Variation of diethanolamines differing in the size and branching of N-substituents (methyl, n-butyl, and tert-butyl), as well as the amount of these groups, allowed the structure of polymer molecules to be preset during their synthesis. To assess the hydrate and corrosion inhibition efficiency of developed reagents pressurized rocking cells, electrochemistry and weight-loss techniques were used. A distinct effect of these variables altering the hydrophobicity of obtained compounds on their target properties was revealed. Polymers with increased content of diethanolamine fragments with n- or tert-butyl as N-substituent (WPU-6 and WPU-7, respectively) worked as dual-function inhibitors, showing nearly the same efficiency as commercial ones at low concentration (0.25 wt%), with the branched one (tert-butyl; WPU-7) turning out to be more effective as a corrosion inhibitor. Commercial kinetic hydrate inhibitor Luvicap 55 W and corrosion inhibitor Armohib CI-28 were taken as reference samples. Preliminary study reveals that WPU-6 and WPU-7 polyurethanes as well as Luvicap 55 W are all poorly biodegradable compounds; BODt/CODcr (ratio of Biochemical oxygen demand and Chemical oxygen demand) value is 0.234 and 0.294 for WPU-6 and WPU-7, respectively, compared to 0.251 for commercial kinetic hydrate inhibitor Luvicap 55 W. Since the obtained polyurethanes have a bifunctional effect and operate at low enough concentrations, their employment is expected to reduce both operating costs and environmental impact