• Energy Research

The application of carbon capture and storage (CCS) and carbon neutral techniques should be adopted to reduce the CO2 emissions from power generation systems. These environmental concerns have renewed interest towards the use of biomass as an alternative to fossil fuels. This study investigates the comparative potential of different power generation systems, including NGCC with and without exhaust gas recirculation (EGR), pulverised supercritical coal and biomass fired power plants for constant heat input and constant fuel flowrate cases. The modelling of all the power plant cases is realized in Aspen Plus at the gross power output of 800 MWe and integrated with a MEA-based CO2 capture plant and a CO2 compression unit. Full-scale detailed modelling of integrated power plant with a CO2 capture and compression system for biomass fuel for two different cases is reported and compared with the conventional ones. The process performance, in terms of efficiency, emissions and potential losses for all the cases, is analysed. In conclusion, NGCC and NGCC with EGR integrated with CO2 capture and compression results in higher net efficiency and least efficiency penalty reduction. Further, coal and biomass fired power plants integrated with CO2 capture and compression results in higher specific CO2 capture and the least specific losses per unit of the CO2 captured. Furthermore, biomass with CO2 capture and compression results in negative emissions.

Modern ironmaking process relies significantly on fossil-related fuels, which ultimately results in the enormous CO2 emitted into the atmosphere. Biomass of plant origin, as a carbon-neutral energy source, has been considered as an alternative to fossil-based reducing agents such as coke. This study aims to investigate the potential of three woody biomass waste derivatives produced from biomass waste pyrolysis and gasification, namely charcoal, bio-oil, and bio-syngas, as the reducing agents in blast furnace. A model based on heat and mass balance and Gibbs free energy minimisation is proposed to simulate an ironmaking process with assistance of these derivatives. The effects of specific composition of biomass waste derivatives on process operation, CO2 emissions, and coke replacement are explored. Also the effects of H2-rich gas produced from biomass waste gasification on the blast furnace operation are estimated. Results indicate that reactions of woody biomass waste derivatives in blast furnace are complex and greatly dependent on composition. When charcoal has a higher carbon content, lower CO2 concentration is found from the top gas. The higher content of hydrogen in bio-oil will inhibit further reduction in CO2 emissions. Bio-syngas with H2/CO ratio of 1.3 proves to have a remarkable potential to reduce CO2 emissions. From the aspects of available biomass waste resources across the world, woody biomass waste derivatives as reducing agents are more suitable for countries with the limited pig iron production. This study provides a reference on the future of moving forward the decarbonised ironmaking by using woody biomass waste derivatives.

Abstract This paper evaluates the introduction of carbon capture and storage (CCS) to Mexico. The gasification technology is presented as a potential alternative to be applied into refinery plants due to high petcoke production. Although economic aspects, such as fuel price and selling CO2, are important in the selection of CCS alternatives, there are other limitations, i.e. water availability and space. In March 2014, Mexico launched its CCS technological roadmap. However, an evaluation of the installation of new CO2-capture ready power plants was not considered. For that reason, this study could be useful to create a technology roadmap that includes the design of CO2 capture plants into refineries and how they will have to operate for CO2 emissions reduction, and taking advantage that most of refineries and petrochemical plants are close to oil fields for enhanced oil recovery (EOR). Integrated gasification combined cycle (IGCC) with CCS was chosen in this paper for power generation using petcoke as feedstock. The emissions of CO2 in kg/kWh could be reduced by 68%.

Abstract In this work, the feasibility of a novel method of cryogenic carbon capture based on carbon dioxide frost deposition onto a cold moving bed is explored. As a gas mixture including CO2 flows through a sufficiently cold packed bed, CO2 is deposited onto the bed material as a frost. As the bed is warmed by the gas stream the frost front advances through the bed. Experimental measurements of the rate of frost advance within a static packed bed are used to set up a moving bed to achieve continuous CO2 removal. Precooled and dry binary gas mixtures of CO2 and nitrogen are used to determine frost front velocity in a capture column. The frost front velocity measured in fixed bed experiments with varying CO2 concentrations and gas flow rates are in the range of 0.4–1 mm/s. The experimental results were used to design a moving bed system that would match this range of frost front velocities so that continuous capture would be possible. Experiments were conducted to investigate the behaviour of temperature profiles within the capture column under moving bed conditions. These show that frost accumulation does not occur and successfully demonstrates continuous cryogenic carbon capture.

The deployment of post-combustion CO2 capture on large-scale gas-fired power plants is\ud currently progressing, hence the integration of the power and capture plants requires a\ud good understanding of operational requirements and limitations to support this effort. This\ud article aims to assist research in this area, by studying a micro gas turbine (MGT) integrated\ud with an amine-based post-combustion CO2 capture unit. Both processes were simulated\ud using two different software tools – IPSEpro and Aspen Hysys, and validated against\ud experimental tests. The two MGT models were benchmarked at the nominal condition, and\ud then extended to part-loads (50 and 80 kWe), prior to their integration with the capture\ud plant at flue gas CO2 concentrations between 5 and 10 mol%. Further, the performance of\ud the MGT and capture plant when gas turbine exhaust gases were recirculated was assessed.\ud Exhaust gas recirculation increases the CO2 concentration, and reduces the exhaust gas\ud flowrate and specific reboiler duty. The benchmarking of the two models revealed that the\ud IPSEpro model can be easily adapted to new MGT cycle modifications since turbine\ud temperatures and rotational speeds respond to reaching temperature limits; whilst a\ud detailed rate-based approach for the capture plant in Hysys resulted in closely aligned\ud simulation results with experimental data.\ud

Abstract This work considers the use of spent poultry litter as a fuel for on-site power generation. On-site use eliminates the need for the transportation of biomass to centralised plants and the associated bio-security issues. This work utilised process simulation to investigate six process integration schemes applied to a small scale gasification unit with a gas turbine prime mover. The model was used to evaluate schemes involving atmospheric gasification, pressurised gasification and recuperation of energy from the gas turbine exhaust gases. The recuperation of residual heat to preheat air and produced gases was performed with the aim of achieving the highest electrical efficiency. The cold gasification and exergy efficiencies were in the ranges of 58.4–79.5% and 46.8–65.7%, respectively, which mainly increased with increasing ER and then after achieving the maximum value declined. The preferred configuration of the proposed 200-kW process achieved electrical efficiencies between 26% and 33.5%.

Abstract Environmental implications of the disposal of waste from the poultry industry have created the need for proper waste management. As a result, poultry litter has been proposed as a potential fuel candidate for thermal conversion technologies since it is an available source. This review discusses the recent advances in the physical and chemical characterisation of poultry litter. The focus of this review is on gasification for energy generation and current commercial combustion facilities. Significant advances have been made in the pyrolysis, gasification and combustion investigations with the aim to determine their kinetics. These results are important for modelling work and critical issues for the simulation of poultry litter gasification are discussed.

AbstractAn integrated model of a micro-turbine coupled to a CO2 capture plant has been developed with Aspen Plus, and validated with experimental data obtained from a Turbec T100 microturbine at the PACT facilities in the UKCCS Research Centre, Beighton, UK. Monoethanolamine (MEA) was used as solvent and experimental measurements from the CO2 capture plant have been used to validate the steady-state model developed with Aspen Plus®. The optimum liquid/gas ratio and the lean CO2 loading for 90% CO2 capture has been quantified for flue gases with CO2 concentrations ranging from 3 to 8 mol%.