ABSTRACT Solvent-based post-combustion carbon capture (PCC) technology though being the best avai... more ABSTRACT Solvent-based post-combustion carbon capture (PCC) technology though being the best available option for large-scale carbon capture and sequestration (CCS) projects, faces the drawback of high energy intensity and large capital cost. Therefore, process optimization plays a key role in further improvement of the performance efficiency and curbing the costs. The PCC technology involves complex reactive separations for which achieving the goal of an optimized process requires existence of a rigorous design methodology considering both operation and design parameters. In this paper, an equation-based methodology is developed for optimal synthesis and design of absorption and desorption columns considering rate-based interaction of the gas and liquid. The design methodology considers all the influential techno-economic parameters such as number of absorber/desorber columns, height and diameter of columns, operating conditions (P, T) of columns, pressure drop, packing type, percentage of CO2 avoided, captured CO2 purity, amount of regeneration, and flooding velocities of columns. An example is solved for a 300 MW coal-fired power plant and numerous parametric analyses are performed using 30 wt% monoethanolamine (MEA) solvent. The parametric study shows that the design and operation parameters are markedly interactive, and that a successful solvent-based PCC design requires concurrent consideration of both aspects.
ABSTRACT There has been an increasing interest in the application of membranes to flue gas separa... more ABSTRACT There has been an increasing interest in the application of membranes to flue gas separation, primarily driven by the need of carbon capture for significantly reducing greenhouse gas emissions. Historically, there has not been general consensus about the advantage of membranes against other methods such as liquid solvents for carbon capture. However, recent research indicates that advances in materials and process designs could significantly improve the separation performance of membrane capture systems, which make membrane technology competitive with other technologies for carbon capture. This paper mainly reviews membrane separation for the application to post-combustion CO2 capture with a focus on the developments and breakthroughs in membrane material design, process engineering, and engineering economics.
ABSTRACT Heat pipes (HP) are efficient heat transfer devices, utilizing a working fluid to transf... more ABSTRACT Heat pipes (HP) are efficient heat transfer devices, utilizing a working fluid to transfer heat based on evaporation and condensation. To make HPs even more efficient, one viable approach is to modify the utilized working fluid thermophysical properties. In this paper, a simple yet effective method based on dimensional analysis, leading to a reduced-order model, is proposed to analyze and modify working fluid's thermophysical properties and to predict the impact of working fluid modification on thermal resistance of a trapezoidal micro-grooved heat pipe. A validated one dimensional mathematical model based on a semi-analytical hydrodynamic approach is used to estimate the reduced-order model parameters. Alternatively, experimental data can be used for estimation of the reduced-order model parameters. The reduced model is further used to analyze and quantify the contribution of each of the thermophysical properties of working fluid on heat pipe thermal resistance. The simplified reduced-order model yielded a dimensionally reduced form of the numerical model which revealed constant thermal resistance contours. In addition, the reduced-order model successfully predicted the performance of the heat pipe when filled with different working fluids. It is also found that high thermal conductivity, low surface tension, low latent heat of evaporation, high viscosity, and low liquid density are the most favourable thermophysical properties of the working fluid leading to improvement of heat pipe thermal resistance, respectively. The proposed method for working fluid modification is generic and thus applicable to a range of situations associated with the selection and/or design of heat pipe working fluids and mixtures thereof.
ABSTRACT Natural gas liquefaction processes are energy and cost intensive. This paper performs th... more ABSTRACT Natural gas liquefaction processes are energy and cost intensive. This paper performs thermodynamic and economic optimization of the mid-scale mixed refrigerant cycles including propane precooled mixed refrigerant (C3MR) and dual mixed refrigerant (DMR) processes. Four different objective functions in this study are selected: total shaft work consumption, total cost investment (TCI), total annualized cost (TAC), and total capital cost of compressors and main cryogenic exchangers (MCHEs). Total cost investment (TCI) is a function of two key variables: shaft work (W) and overall heat transfer coefficient and area (UA) of MCHEs. It is proposed for reducing energy consumption and simultaneously minimizing total capital expenditure (CAPEX) and operating expenditure (OPEX). Total shaft work objective function can result in a 44.5% reduction of shaft work for C3MR and a 48.6% reduction for DMR compared to their baseline values, but infinitely high UA of MCHEs. Optimal results show that total capital cost of compressors and MCHEs is more suitable than other objective functions for the objective of reducing both shaft work and UA. It reduces 14.5% of specific power for C3MR and 26.7% for DMR when achieving the relatively lower UA values than their baseline values. In addition, TCI and TAC can also reduce a certain amount of total shaft work at a finite increased UA.
ABSTRACT The use of pure substrate represents a significant proportion of the cost of manufacturi... more ABSTRACT The use of pure substrate represents a significant proportion of the cost of manufacturing a drug such as lovastatin. This study explores the production of lovastatin and (+)-geodin by Aspergillus terreus ATCC 20542 using biodiesel-derived crude glycerol (CG) as a feedstock. Shake flask experiments showed reduced lovastatin production and glycerol consumption in the presence of 10–50 g/L CG with respect to pure glycerol (PG) controls. At 50 g/L, lovastatin and (+)-geodin production was significantly reduced by 82% and 73%, respectively. The lowest lovastatin inhibition was detected in 30 g/L of CG (48%), which was accompanied by a significant rise in (+)-geodin production (338%). Further investigation was performed on three major impurities found in CG, namely methanol (MeOH), sodium chloride (NaCl) and fatty acids (oleic and palmitic acids, soap). None was particularly inhibitory for lovastatin, except soap and palmitic acids, which reduced its production by more than 50% at all concentrations tested. In contrast, (+)-geodin was inhibited in the presence of MeOH and palmitic acid by up to 46% and 91%, respectively. These observations indicate that partial purification of CG would be potentially useful in improving production of lovastatin and (+)-geodin by A. terreus.This article is protected by copyright. All rights reserved
ABSTRACT Solvent-based post-combustion carbon capture (PCC) technology though being the best avai... more ABSTRACT Solvent-based post-combustion carbon capture (PCC) technology though being the best available option for large-scale carbon capture and sequestration (CCS) projects, faces the drawback of high energy intensity and large capital cost. Therefore, process optimization plays a key role in further improvement of the performance efficiency and curbing the costs. The PCC technology involves complex reactive separations for which achieving the goal of an optimized process requires existence of a rigorous design methodology considering both operation and design parameters. In this paper, an equation-based methodology is developed for optimal synthesis and design of absorption and desorption columns considering rate-based interaction of the gas and liquid. The design methodology considers all the influential techno-economic parameters such as number of absorber/desorber columns, height and diameter of columns, operating conditions (P, T) of columns, pressure drop, packing type, percentage of CO2 avoided, captured CO2 purity, amount of regeneration, and flooding velocities of columns. An example is solved for a 300 MW coal-fired power plant and numerous parametric analyses are performed using 30 wt% monoethanolamine (MEA) solvent. The parametric study shows that the design and operation parameters are markedly interactive, and that a successful solvent-based PCC design requires concurrent consideration of both aspects.
ABSTRACT There has been an increasing interest in the application of membranes to flue gas separa... more ABSTRACT There has been an increasing interest in the application of membranes to flue gas separation, primarily driven by the need of carbon capture for significantly reducing greenhouse gas emissions. Historically, there has not been general consensus about the advantage of membranes against other methods such as liquid solvents for carbon capture. However, recent research indicates that advances in materials and process designs could significantly improve the separation performance of membrane capture systems, which make membrane technology competitive with other technologies for carbon capture. This paper mainly reviews membrane separation for the application to post-combustion CO2 capture with a focus on the developments and breakthroughs in membrane material design, process engineering, and engineering economics.
ABSTRACT Heat pipes (HP) are efficient heat transfer devices, utilizing a working fluid to transf... more ABSTRACT Heat pipes (HP) are efficient heat transfer devices, utilizing a working fluid to transfer heat based on evaporation and condensation. To make HPs even more efficient, one viable approach is to modify the utilized working fluid thermophysical properties. In this paper, a simple yet effective method based on dimensional analysis, leading to a reduced-order model, is proposed to analyze and modify working fluid's thermophysical properties and to predict the impact of working fluid modification on thermal resistance of a trapezoidal micro-grooved heat pipe. A validated one dimensional mathematical model based on a semi-analytical hydrodynamic approach is used to estimate the reduced-order model parameters. Alternatively, experimental data can be used for estimation of the reduced-order model parameters. The reduced model is further used to analyze and quantify the contribution of each of the thermophysical properties of working fluid on heat pipe thermal resistance. The simplified reduced-order model yielded a dimensionally reduced form of the numerical model which revealed constant thermal resistance contours. In addition, the reduced-order model successfully predicted the performance of the heat pipe when filled with different working fluids. It is also found that high thermal conductivity, low surface tension, low latent heat of evaporation, high viscosity, and low liquid density are the most favourable thermophysical properties of the working fluid leading to improvement of heat pipe thermal resistance, respectively. The proposed method for working fluid modification is generic and thus applicable to a range of situations associated with the selection and/or design of heat pipe working fluids and mixtures thereof.
ABSTRACT Natural gas liquefaction processes are energy and cost intensive. This paper performs th... more ABSTRACT Natural gas liquefaction processes are energy and cost intensive. This paper performs thermodynamic and economic optimization of the mid-scale mixed refrigerant cycles including propane precooled mixed refrigerant (C3MR) and dual mixed refrigerant (DMR) processes. Four different objective functions in this study are selected: total shaft work consumption, total cost investment (TCI), total annualized cost (TAC), and total capital cost of compressors and main cryogenic exchangers (MCHEs). Total cost investment (TCI) is a function of two key variables: shaft work (W) and overall heat transfer coefficient and area (UA) of MCHEs. It is proposed for reducing energy consumption and simultaneously minimizing total capital expenditure (CAPEX) and operating expenditure (OPEX). Total shaft work objective function can result in a 44.5% reduction of shaft work for C3MR and a 48.6% reduction for DMR compared to their baseline values, but infinitely high UA of MCHEs. Optimal results show that total capital cost of compressors and MCHEs is more suitable than other objective functions for the objective of reducing both shaft work and UA. It reduces 14.5% of specific power for C3MR and 26.7% for DMR when achieving the relatively lower UA values than their baseline values. In addition, TCI and TAC can also reduce a certain amount of total shaft work at a finite increased UA.
ABSTRACT The use of pure substrate represents a significant proportion of the cost of manufacturi... more ABSTRACT The use of pure substrate represents a significant proportion of the cost of manufacturing a drug such as lovastatin. This study explores the production of lovastatin and (+)-geodin by Aspergillus terreus ATCC 20542 using biodiesel-derived crude glycerol (CG) as a feedstock. Shake flask experiments showed reduced lovastatin production and glycerol consumption in the presence of 10–50 g/L CG with respect to pure glycerol (PG) controls. At 50 g/L, lovastatin and (+)-geodin production was significantly reduced by 82% and 73%, respectively. The lowest lovastatin inhibition was detected in 30 g/L of CG (48%), which was accompanied by a significant rise in (+)-geodin production (338%). Further investigation was performed on three major impurities found in CG, namely methanol (MeOH), sodium chloride (NaCl) and fatty acids (oleic and palmitic acids, soap). None was particularly inhibitory for lovastatin, except soap and palmitic acids, which reduced its production by more than 50% at all concentrations tested. In contrast, (+)-geodin was inhibited in the presence of MeOH and palmitic acid by up to 46% and 91%, respectively. These observations indicate that partial purification of CG would be potentially useful in improving production of lovastatin and (+)-geodin by A. terreus.This article is protected by copyright. All rights reserved
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