Papers by Keyword: CO₂ Removal

Abstract: Low Pressure (LP) flash column is one of the equipment at CO₂ removal plant, operated since 2003 with a design pressure and temperature of 1.75 kg/cm²g and 90 °C, respectively. The LP flash column functions as a place for the CO₂ gas to be absorbed by aMDEA and produces lean amine. At turn around in 2021, a crack with a length approximately 5 cm was found on the inside of the top part of the LP flash column (shell area near weld). Repairment was carried out by providing a crack stopper on the crack tip, gouging, non-destructive evaluation (NDE) and welding. However, when NDE was applied, new cracks appeared around the initial crack. Some inspection and testing were further carried out to find the root cause and appropriate repair method. The results indicate that the crack has a branching pattern and its propagation cuts through trans-granular grain. Upon further analysis, there was unusually higher chloride content on the crack surface area and hardness value was higher (202-209 HB) than standard hardness value for ASTM A240-304L (≤ 201 HB) which indicates the crack was caused by chloride stress corrosion cracking (Cl-SCC). Excessive load or stress caused cracks to propagate rapidly and uncontrolled. Based on ASME PCC-2, the Butt Weld Insert Plate was selected as the repair method due to its suitability for a wide range of defects, its ability to reduce crack propagation and its provision of a permanent repair solution. Another NDE was conducted after the repair to ensure that the repairs were properly executed, with no welding defects or new cracks in the repair area. The results confirmed that there were no defects in the shell material following the installation of the butt weld insert plate.

Abstract: Gas separation membranes are one of the most important processes in purifying natural gas. CO₂ reduction of natural gas is essential for purifying the gas and increasing its calorific value. A covalent organic framework (COF) has been developed as a filler in mixed-matrix membranes (MMM) to separate gases. COF materials were chosen because of their economical rate, good thermal and chemical stability, and flexible microporous structure. Mixed matrix membranes (MMMs) have received significant interest for their improved permeability and selectivity in natural gas purification. The results of using COF combined with other chemicals added to MMM. It has been observed that CO₂ permeability increases as the COF content in the MMM increases, which enhances the gas-separation performance of the MMM. This review evaluated and analyzed the current scientific and the technical breakthroughs in developing MMMs, especially the unique type of organic fillers, which has been the basis of numerous new research for CO₂ separation.

Abstract: The capture of carbon dioxide (CO₂) by aqueous alkanolamine is the most cost effective technology available today. However, some problem such as amine losses, corrosion and low absorption rate arise when aqueous alkanolamines is used as an absorbent. To overcome these problems, liquid emulsion was introduced as an alternative for CO₂ removal. However, the main concern of using liquid emulsion is the stability of the emulsion. In this study, a formulation containing mixture of blended alkanolamine was used. Methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) were used as extractants and were mixed with sodium hydroxide (NaOH) solution to form the aqueous phase. Meanwhile, the organic phase consists of kerosene and Span 80. The emulsion was prepared by homogenizing both phases at speed of 10 000 rpm for five minutes. The stability of the MDEA-AMP emulsion was determined and the CO₂ absorption by the emulsion was measured. This study showed that using 8 mL MDEA and 4mL AMP, the stability of the emulsion was 74.00% and 48.05% of CO₂ was removed.

Abstract: Culture conditions are very important to CO₂ bio-fixation related with the CO₂ removal efficiency through biological process by microalgae photosynthesis activities. The aim of the research was to study how high CO₂ utilization efficiency could reach in mix culture that supplied high CO₂ concentration (2%, 5%, and 7%) continuously from the bottom of photobioreactor. The mix microalgae culture containing of Chlorella sp, Scenedesmus obliquus and Ankistrodemus sp. were cultivated in photobioreactor with various environmental treatments i.e light intensities, light periodism and temperatures whereas the fixed CO₂ gas flow rate of 8 L.min^-1. The results showed that microalgae growth was best at light intensity of 4000 lux for 16/8 hours light/darkness cycling, 30°C and 5% CO₂ supplied, indicated by the highest dried biomass (g.L^-1), the highest Carbon content was g.d^-1 and highest CO₂ removal efficiency (%) that were 2.7, 11.9, 49, respectively. However the highest CO₂ utilization efficiency for bio-fixation phenomenon was obtained from culture that supplied by 2% CO₂ concentration, the value was almost 2 fold than 5% CO₂ supplied and 4 fold than 7% CO₂ concentration supplied, respectively. Biological fixation of CO₂ are greatly affected by the characteristics of the microalgae strains and their tolerance to environmental conditions.

Abstract: PEAm-TMC/PDMS/PVC composite hollow fiber membrane for CO₂ separation was developed through interfacial polymerization (IP) on the PDMS pre-coated inner surface of PVC hollow fiber. Polyetheramine (PEAm) and Trimesoyl chloride (TMC) were selected as aqueous monomer and organic monomer, respectively. SEM observation result shows that the thickness of PEAm-TMC IP layer is about 215 nm. The effects of monomer concentrations and acid acceptor concentration on the membrane performance were investigated. The results shows that the CO₂ permeance decareses and CO₂/N₂ selectivity increases with the increasing concentrations of PEAm, TMC and Na₂CO₃. At 0.12 MPa, the composite hollow fiber membrane possesses a very high CO₂ permeance of 964 GPU and CO₂/N₂ selectivity of 40.6.