Parametric study and economic evaluation of a simulated biogas upgrading plant
- Authors: Masebinu, Samson Oluwasegun
- Date: 2015-06-25
- Subjects: Sewage disposal plants - Biodegradation , Sewage disposal plants - Energy conservation , Sewage - Purification - Anaerobic treatment , Water - Purification - Biological treatment , Water - Purification - Membrane filtration , Sewage - Purification - Filtration
- Type: Thesis
- Identifier: uj:13616 , http://hdl.handle.net/10210/13799
- Description: M. Tech. (Chemical Engineering) , The usual target of an upgrading process using membrane is to produce a retentate stream, the product, with high CH4 concentration. This work presents a simulation of two possible membrane configurations, single stage without recycle (SSWR) and double stage with permeate recycle (DSPR), of an existing operational biogas upgrading plant. The simulation was conducted using ChemCAD and AlmeeSoft gas permeation software to investigate the performance of the configurations on product purity, recovery and required compressor power with a view to determine the optimal operational conditions for maximising the concentration of CH4 and its recovery. Thereafter, an economic assessment on the optimal configuration was conducted to determine the gas processing cost (GPC), the profitability of producing biomethane and cost-benefit of utilising biomethane as a vehicular fuel. The simulation was validated against plant data with a maximum percentage error of 2.64%. Increasing CO2 in feed reduced product recovery and purity. Increasing feed pressure and selectivity increased product recovery and purity up to the pressure limit of the membrane module. Increasing feed flow rate increased product recovery but reduces purity. In both configurations, increasing CO2 in the feed and increasing feed pressure increased the GPC. However, increasing feed flow rate reduced the GPC. The overall performance of DSPR configuration was much higher due to increased trans-membrane area available for separation. At optimal conditions, a product purity of 91% and 96% CH4 recovery was achieved from the initial plant result of 87.2% product purity and 91.16% CH4 recovery. The total compression duty was 141 kW. The GPC was $0.46/m3 of biomethane. The cumulative discounted NPV, IRR and BCR for producing biomethane was R15,240,343, 22.41% and 2.05 respectively, with a break-even in the 5th year after plant start-up considering a prime lending rate at 9%. Using CBG instead of gasoline saves 34% of annual fuel cost with a payback period of one year and three months for the cost of retrofitting the vehicle.
- Full Text:
- Authors: Masebinu, Samson Oluwasegun
- Date: 2015-06-25
- Subjects: Sewage disposal plants - Biodegradation , Sewage disposal plants - Energy conservation , Sewage - Purification - Anaerobic treatment , Water - Purification - Biological treatment , Water - Purification - Membrane filtration , Sewage - Purification - Filtration
- Type: Thesis
- Identifier: uj:13616 , http://hdl.handle.net/10210/13799
- Description: M. Tech. (Chemical Engineering) , The usual target of an upgrading process using membrane is to produce a retentate stream, the product, with high CH4 concentration. This work presents a simulation of two possible membrane configurations, single stage without recycle (SSWR) and double stage with permeate recycle (DSPR), of an existing operational biogas upgrading plant. The simulation was conducted using ChemCAD and AlmeeSoft gas permeation software to investigate the performance of the configurations on product purity, recovery and required compressor power with a view to determine the optimal operational conditions for maximising the concentration of CH4 and its recovery. Thereafter, an economic assessment on the optimal configuration was conducted to determine the gas processing cost (GPC), the profitability of producing biomethane and cost-benefit of utilising biomethane as a vehicular fuel. The simulation was validated against plant data with a maximum percentage error of 2.64%. Increasing CO2 in feed reduced product recovery and purity. Increasing feed pressure and selectivity increased product recovery and purity up to the pressure limit of the membrane module. Increasing feed flow rate increased product recovery but reduces purity. In both configurations, increasing CO2 in the feed and increasing feed pressure increased the GPC. However, increasing feed flow rate reduced the GPC. The overall performance of DSPR configuration was much higher due to increased trans-membrane area available for separation. At optimal conditions, a product purity of 91% and 96% CH4 recovery was achieved from the initial plant result of 87.2% product purity and 91.16% CH4 recovery. The total compression duty was 141 kW. The GPC was $0.46/m3 of biomethane. The cumulative discounted NPV, IRR and BCR for producing biomethane was R15,240,343, 22.41% and 2.05 respectively, with a break-even in the 5th year after plant start-up considering a prime lending rate at 9%. Using CBG instead of gasoline saves 34% of annual fuel cost with a payback period of one year and three months for the cost of retrofitting the vehicle.
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Anaerobic digestion process stabilisation and in-situ upgrading of a biogas system
- Authors: Masebinu, Samson Oluwasegun
- Date: 2018
- Subjects: Biochar , Biomass energy , Sewage - Purification - Anaerobic treatment , Sewage - Purification - Filtration
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/293937 , uj:31971
- Description: Abstract: Anaerobic digestion (AD) is an established organic waste management technology, producing biogas and organic fertiliser as end-products. Despite being an established technology, AD still faces key challenges, including substrate-induced instability and the requirements for the removal of carbon dioxide (CO2) from biogas. Carbon-based materials have been recently employed as stabilising agent and as adsorbent to manage some of these limitations. Biochar, a by-product from biomass pyrolysis, has been identified as a sustainable alternative material to commercial grade carbon-based adsorbent in AD. However, research on the use of biochar has mostly focused on thermophilic batch AD, without considering the biochar production conditions and how they interact with the AD process at mesophilic conditions. The microbial communities in thermophilic AD are very sensitive to any slight fluctuation in process conditions, hence, the preference for mesophilic digestion is well known. This research investigated the impact of biochar on a mesophilic operated AD process stability and the potential to produce biogas with increased concentrations of methane (CH4) in-situ towards approaching a state of biomethane. The biochar employed was derived from the slow pyrolysis of bamboo, a phytoremediation biomass, and corn stover, the agricultural residue after a harvest of corn. Based on reviewed literature, properties of biochar that favour AD stability, and increased CH4 concentration in biogas were identified and the range of the identified optimal properties were implemented in a design of experiment (DoE). A batch biochemical methane potential test was implemented within the framework of a Taguchi-based DoE. The Taguchi DoE was coupled with grey relational and principal component analyses, in order to objectively identify the optimal combination of parameters that support the aim of this research. Optimal conditions determined from the batch test were replicated in a semi-continuous two-stage experiment by using a control digester and a biochar amended digester... , D.Phil. (Mechanical Engineering)
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- Authors: Masebinu, Samson Oluwasegun
- Date: 2018
- Subjects: Biochar , Biomass energy , Sewage - Purification - Anaerobic treatment , Sewage - Purification - Filtration
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/293937 , uj:31971
- Description: Abstract: Anaerobic digestion (AD) is an established organic waste management technology, producing biogas and organic fertiliser as end-products. Despite being an established technology, AD still faces key challenges, including substrate-induced instability and the requirements for the removal of carbon dioxide (CO2) from biogas. Carbon-based materials have been recently employed as stabilising agent and as adsorbent to manage some of these limitations. Biochar, a by-product from biomass pyrolysis, has been identified as a sustainable alternative material to commercial grade carbon-based adsorbent in AD. However, research on the use of biochar has mostly focused on thermophilic batch AD, without considering the biochar production conditions and how they interact with the AD process at mesophilic conditions. The microbial communities in thermophilic AD are very sensitive to any slight fluctuation in process conditions, hence, the preference for mesophilic digestion is well known. This research investigated the impact of biochar on a mesophilic operated AD process stability and the potential to produce biogas with increased concentrations of methane (CH4) in-situ towards approaching a state of biomethane. The biochar employed was derived from the slow pyrolysis of bamboo, a phytoremediation biomass, and corn stover, the agricultural residue after a harvest of corn. Based on reviewed literature, properties of biochar that favour AD stability, and increased CH4 concentration in biogas were identified and the range of the identified optimal properties were implemented in a design of experiment (DoE). A batch biochemical methane potential test was implemented within the framework of a Taguchi-based DoE. The Taguchi DoE was coupled with grey relational and principal component analyses, in order to objectively identify the optimal combination of parameters that support the aim of this research. Optimal conditions determined from the batch test were replicated in a semi-continuous two-stage experiment by using a control digester and a biochar amended digester... , D.Phil. (Mechanical Engineering)
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