• Energy Research

Abstract In this work, perovskite BaBiO3−δ disk membranes were synthesized with the molar ratio (z) of BiO1.5 to BaO between 0.5 and 3 at varying sintering temperatures. Disk membranes with z > 1.33, associated with a lower amount of Bi-rich perovskite phase, showed mechanically weak properties while membranes with z ≤ 1 showed superior stability at temperatures in excess of 800 °C. The best performance was obtained for the z = 0.86 disk membrane, reaching oxygen fluxes of 1.2 ml min−1 cm−2 at 950 °C. This was attributed to the higher sintering temperature and the formation of oxygen deficient phase of BaBiO3−δ perovskite. For gas testing temperatures above 800 °C, it was found that the oxygen permeation was limited by both bulk diffusion and surface kinetics as oxygen flux did not increase proportionally to the inverse of membrane thickness reduction. Further analysis showed that the activation energy for oxygen ionic transport changed at 800 °C, however the z = 1 sample displayed the opposite trend from other compositions, indicating the formation of more oxygen vacancies in the crystal lattice. Mechanically stable disk membranes exposed to thermal cycling tests resulted in crystal structure instability of the pure perovskite (z = 1) and loss of oxygen vacancies while the z 1 sample showed superior thermal cycling and crystal structure stability.

Abstract In this work, perovskite BaBiO3−δ disk membranes were synthesized with the molar ratio (z) of BiO1.5 to BaO between 0.5 and 3 at varying sintering temperatures. Disk membranes with z > 1.33, associated with a lower amount of Bi-rich perovskite phase, showed mechanically weak properties while membranes with z ≤ 1 showed superior stability at temperatures in excess of 800 °C. The best performance was obtained for the z = 0.86 disk membrane, reaching oxygen fluxes of 1.2 ml min−1 cm−2 at 950 °C. This was attributed to the higher sintering temperature and the formation of oxygen deficient phase of BaBiO3−δ perovskite. For gas testing temperatures above 800 °C, it was found that the oxygen permeation was limited by both bulk diffusion and surface kinetics as oxygen flux did not increase proportionally to the inverse of membrane thickness reduction. Further analysis showed that the activation energy for oxygen ionic transport changed at 800 °C, however the z = 1 sample displayed the opposite trend from other compositions, indicating the formation of more oxygen vacancies in the crystal lattice. Mechanically stable disk membranes exposed to thermal cycling tests resulted in crystal structure instability of the pure perovskite (z = 1) and loss of oxygen vacancies while the z 1 sample showed superior thermal cycling and crystal structure stability.

Abstract The glycol purity limit in conventional absorption-based natural gas dehydration process has led to the significant water vapour presence in the supposedly dry product gas. Several alternative processes have been developed to overcome this limitation that includes stripping gas injection using nitrogen, a portion of dry product gas, or volatile hydrocarbon (DRIZO process), stripping gas modified with Stahl column, and Coldfinger technology. This review summarises these different processes and elaborates on their mechanisms, process flow diagram, advantages, drawbacks, and current statuses. Relevant works from 1991 to 2017 were compiled and the existing gaps were highlighted as recommendation for future work.

Abstract The glycol purity limit in conventional absorption-based natural gas dehydration process has led to the significant water vapour presence in the supposedly dry product gas. Several alternative processes have been developed to overcome this limitation that includes stripping gas injection using nitrogen, a portion of dry product gas, or volatile hydrocarbon (DRIZO process), stripping gas modified with Stahl column, and Coldfinger technology. This review summarises these different processes and elaborates on their mechanisms, process flow diagram, advantages, drawbacks, and current statuses. Relevant works from 1991 to 2017 were compiled and the existing gaps were highlighted as recommendation for future work.

This work presents a two-step method to reduce the energy consumption (in terms of the reboiler duty) of a natural gas sweetening process via a physical-chemical solvent mixture (Step 1) followed by a techno-economic analysis of 15 different absorber-stripper configurations (Step 2). Initially, an amine-based sweetening process using a H2S-free sour gas was simulated on Aspen HYSYS and the simulation results were validated against real plant data. In Step 1, different ratios of Sulfinol-M and Sulfinol-D based sweetening process were simulated and the superior physical-chemical solvent mixture that provides the lowest reboiler duty while meeting the sweet gas CO2 product concentration specification (i.e., less than 2 mol.%) is the Sulfinol-M solvent that contains 38 wt.% methyl diethanolamine (MDEA), 40 wt.% Sulfolane, and 22 wt.% water. This Sulfinol-M based model is then optimized via a parametric analysis to further improve its performance in terms of the reboiler duty prior to Step 2. The optimized Sulfinol-M based model achieved 65% saving in the reboiler duty while fulfilling the CO2 concentration specification in product gas relative to the base case. In Step 2, four main absorber-stripper configurations, namely absorber intercooling (AI), lean amine stream split flow (LASSF), rich amine stream split flow (RASSF), and mechanical vapor recompression (MVR) along with their 11 possible combinations were simulated in an attempt to decrease the energy consumption of the process and hence, ranked based on their total cost of production (TCOP). The results revealed that the integration of LASSF + RASSF provides the best option as it achieved the lowest TCOP of $4.60 M while fulfilling the CO2 concentration in product gas and contributed to 6.39% savings in the reboiler duty compared to the optimized conventional Sulfinol-M based model.

This work presents a two-step method to reduce the energy consumption (in terms of the reboiler duty) of a natural gas sweetening process via a physical-chemical solvent mixture (Step 1) followed by a techno-economic analysis of 15 different absorber-stripper configurations (Step 2). Initially, an amine-based sweetening process using a H2S-free sour gas was simulated on Aspen HYSYS and the simulation results were validated against real plant data. In Step 1, different ratios of Sulfinol-M and Sulfinol-D based sweetening process were simulated and the superior physical-chemical solvent mixture that provides the lowest reboiler duty while meeting the sweet gas CO2 product concentration specification (i.e., less than 2 mol.%) is the Sulfinol-M solvent that contains 38 wt.% methyl diethanolamine (MDEA), 40 wt.% Sulfolane, and 22 wt.% water. This Sulfinol-M based model is then optimized via a parametric analysis to further improve its performance in terms of the reboiler duty prior to Step 2. The optimized Sulfinol-M based model achieved 65% saving in the reboiler duty while fulfilling the CO2 concentration specification in product gas relative to the base case. In Step 2, four main absorber-stripper configurations, namely absorber intercooling (AI), lean amine stream split flow (LASSF), rich amine stream split flow (RASSF), and mechanical vapor recompression (MVR) along with their 11 possible combinations were simulated in an attempt to decrease the energy consumption of the process and hence, ranked based on their total cost of production (TCOP). The results revealed that the integration of LASSF + RASSF provides the best option as it achieved the lowest TCOP of $4.60 M while fulfilling the CO2 concentration in product gas and contributed to 6.39% savings in the reboiler duty compared to the optimized conventional Sulfinol-M based model.

Contains fulltext : 295449.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 295449.pdf (Publisher’s version ) (Open Access)