Abstract: CO2 captured from fossil-fueled power generation plants is said to be economically transported via pipelines over long distances. The CO2 must be compressed to pipeline specifications using compressors and pumps that are driven by gas turbine (GT) or other prime movers. This paper presents the evaluation of actual work transfer or required prime power by modeling the governing equations of compression using the Peng–Robinson equation of state (PR-EOS). A computer code was developed to carry out the modeling and subsequent simulation of the compression power requirement. The simulation of prime mover power was carried out for different technology (head per stage) of the compressor ranging from 10-staged compression to double stage compression. The results show that the current technology of the centrifugal compressor could require as much as 23MW of prime mover power to compress 1.5 million tonnes per year of CO2—a projected equivalent CO2 released from a 530MW combined cycle gas turbine (CCGT) power generation plant.
Abstract: Membrane gas separation for carbon capture has traditionally been focused on high pressure applications, such as pre-combustion capture and natural gas sweetening. Recently a membrane-cryogenic combined process has been shown to be cost competitive for post-combustion capture from coal fired power stations. Here, the membrane-cryogenic combined process is investigated for application to post-combustion carbon capture from the flue gas of a Natural Gas Combined Cycle (NGCC) process. This process involves a three-membrane process, where the combustion air is used as the sweep gas on the second membrane stage to recycle CO2 through the turbine. This ensures high CO2 recovery and also increases the CO2 partial pressure in the flue gas. The three-CO2-selective membrane process with liquefaction and O2-enrichment was found to have a cost of capture higher than the corresponding process for coal post-combustion capture. This was attributed to the large size and energy duty of the gas handling equipment, especially the feed blower, because of the high gas throughput in the system caused by significant CO2 recycling. In addition, the economics were uncompetitive compared to a modelled solvent absorption processes for NGCC.
Abstract: The conventional separation system for the recovery of palm kernel from its palm shell–kernel mixture using water as process media generates a considerable amount of waste effluent that harms the environment. The aim of this study is to develop a dry separation process for the recovery of palm kernel by using winnowing columns. A commercial system consisting of a series of five winnowing columns was developed and installed at a local palm oil mill. The system parameters, including column height, blower capacity, airflow rate and mesh screen size for shell removal, were studied and optimized to ensure good separation of kernel and shell in the column to enable collection of different sizes of kernel and shell at each column outlet. The performance of the separation process was evaluated in terms of its kernel losses, dirt content and kernel recovery rate. The average kernel losses based on oil palm fresh fruit bunches processed were found to vary from 0.11 to 0.30 wt %, with most of the values obtained being below the targeted limit of 0.30 wt %. The dirt content was in the range 4.56–6.03 wt %, which was mostly below the targeted limit of 5.5 wt %. The kernel recovery rate was in the range 5.69–6.89 wt %, with most of the values achieving the minimum targeted limit of 6.00 wt %. The system operates under completely dry conditions and, therefore, produces zero waste effluent.
Abstract: We propose an approach for super-resolution optical lithography which is based on the inverse of magnetic resonance imaging (MRI). The technique uses atomic coherence in an ensemble of spin systems whose final state population can be optically detected. In principle, our method is capable of producing arbitrary one and two dimensional high-resolution patterns with high contrast.
Abstract: The combination of Chemical Looping Combustion (CLC) with Calcium Looping (CaL) using integrated pellets is an alternative CO2 capture process to the current amine-based sorbent processes, but the pellets lose sorption capacity over time. In this paper, the deactivation behavior of CaO, CuO and CuO/CaO integrated pellets used for multiple (16–20) cycles in a thermogravimetric analyzer was studied. The impact of thermal treatment and the presence of steam on the deactivation were also investigated. Nitrogen physisorption and scanning electron microscopy/energy-dispersive X-ray analysis were used to characterize the pellets. The analysis revealed significant migration of the copper to the surface of the composite pellets, which likely suppressed carbonation capacity by reducing the accessibility of the CaO. While thermal pre-treatment and steam addition enhanced the performance of the base CaO pellets, the former led to cracks in the pellets. In contrast, thermal pretreatment of the CuO/CaO composite pellets resulted in worse CLC and CaL performance.
Abstract: The definition of the ampere will change in the next few years. This electrical base unit of the S.I. will be redefined by fixing the value of the charge quantum, i.e., the electron charge e. As a result electron pumps will become the natural device for the mise en pratique of this new ampere. In the last years semiconductor electron pumps have emerged as the most advanced systems, both in terms of speed and precision. Another figure of merit for a metrological device would be its ability to be predictible and shared. For that reason a mature fabrication process would certainly be an advantage. In this article we present electron pumps made within a CMOS (Complementary Metal Oxide Semiconductor) research facility on 300 mm silicon-on-insulator wafers, using advanced microelectronics tools and processes. We give an overview of the whole integration scheme and emphasize the fabrication steps which differ from the normal CMOS route.