Steam is the typical working fluid to drive turbo-generators in coal-fired power plants. It is an effective working fluid, but some of its energy is extracted in an unusable form when condensed. A Power Recovery ...Steam is the typical working fluid to drive turbo-generators in coal-fired power plants. It is an effective working fluid, but some of its energy is extracted in an unusable form when condensed. A Power Recovery Cycle (PRC) using a more volatile Secondary Working Fluid (SWF) added to the steam cycle could improve energy efficiency. PRCs have been applied to the flue gas and for combined cycle systems but not to traditional plant steam cycles. This paper details an analysis of adding a steam cycle PRC to a 500 MW lignite coal-fired power plant. A validated model of the plant was developed and PRCs using the three most attractive SWFs, benzene, methanol and hydrazine, were then added to the model. Adding a benzene, methanol, or hydrazine steam cycle PRC will produce an additional 59, 34, and 49 MW, respectively. An AACE Class 4 factored broad capital cost estimate and comparable operating costs and revenue estimates were developed to evaluate PRC feasibility. The benzene, methanol, and hydrazine processes had 2019 Net Present Values (NPVs) @12% of -$32, -$59, and +$35 million ± 40%, respectively. Thus, a PRC may be profitable at current or modest increases to U.S. Upper Midwest electricity prices of around $0.0667/kWh.展开更多
The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale.Microalgae contain a higher lipid content on a dry-weight basis compared to oils...The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale.Microalgae contain a higher lipid content on a dry-weight basis compared to oilseeds such as soybeans.Additionally,the growth and cultivation cycle of microalgae is 15 days,in comparison to soybeans,for which the cycle occurs once or twice annually.However,to date,it has been uneconomical to produce microalgae oils in a world-scale facility due to limitations in cultivating microalgae at commercial scales.Recent developments suggest that the use of heterotrophic microalgae may be economically feasible for large-scale oil production.To assess this feasibility,a comparative scoping study was performed analysing the feasibility of an industrial-scale process plant for the growth and extraction of oil from microalgae.Processes were developed at the preliminary design level using heterotrophic subspecies and autotrophic subspecies of Chlorella vulgaris.AACE Class 4 cost estimates and economic analyses were performed.This study concludes that processes based on heterotrophic microalgae are more likely to reach economic feasibility than processes using autotrophic microalgae.However,a few barriers still remain to achieving free-market economic viability.展开更多
文摘Steam is the typical working fluid to drive turbo-generators in coal-fired power plants. It is an effective working fluid, but some of its energy is extracted in an unusable form when condensed. A Power Recovery Cycle (PRC) using a more volatile Secondary Working Fluid (SWF) added to the steam cycle could improve energy efficiency. PRCs have been applied to the flue gas and for combined cycle systems but not to traditional plant steam cycles. This paper details an analysis of adding a steam cycle PRC to a 500 MW lignite coal-fired power plant. A validated model of the plant was developed and PRCs using the three most attractive SWFs, benzene, methanol and hydrazine, were then added to the model. Adding a benzene, methanol, or hydrazine steam cycle PRC will produce an additional 59, 34, and 49 MW, respectively. An AACE Class 4 factored broad capital cost estimate and comparable operating costs and revenue estimates were developed to evaluate PRC feasibility. The benzene, methanol, and hydrazine processes had 2019 Net Present Values (NPVs) @12% of -$32, -$59, and +$35 million ± 40%, respectively. Thus, a PRC may be profitable at current or modest increases to U.S. Upper Midwest electricity prices of around $0.0667/kWh.
基金This work was supported by the National Science Foundation,Grant No.1458962Any opinions,findings and conclusions or recommendations expressed in this material are those of the author(s)and do not necessarily reflect the views of the NSF.
文摘The production of microalgae as a fatty acid oil resource for use in biofuels production is a widespread research topic at the lab scale.Microalgae contain a higher lipid content on a dry-weight basis compared to oilseeds such as soybeans.Additionally,the growth and cultivation cycle of microalgae is 15 days,in comparison to soybeans,for which the cycle occurs once or twice annually.However,to date,it has been uneconomical to produce microalgae oils in a world-scale facility due to limitations in cultivating microalgae at commercial scales.Recent developments suggest that the use of heterotrophic microalgae may be economically feasible for large-scale oil production.To assess this feasibility,a comparative scoping study was performed analysing the feasibility of an industrial-scale process plant for the growth and extraction of oil from microalgae.Processes were developed at the preliminary design level using heterotrophic subspecies and autotrophic subspecies of Chlorella vulgaris.AACE Class 4 cost estimates and economic analyses were performed.This study concludes that processes based on heterotrophic microalgae are more likely to reach economic feasibility than processes using autotrophic microalgae.However,a few barriers still remain to achieving free-market economic viability.
