Regano Benito

Multi-objective thermodynamic optimisation of supercritical CO2 Brayton cycles integrated with solar central receivers

ABSTRACT In this paper, optimisation of the supercritical CO Brayton cycles integrated with a solar receiver, which provides heat input to the cycle, was performed. Four S-CO Brayton cycle configurations were analysed and optimum operating conditions were obtained by using a multi-objective thermodynamic optimisation. Four different sets, each including two objective parameters, were considered individually. The individual multi-objective optimisation was performed by using Non-dominated Sorting Genetic Algorithm. The effect of reheating, solar receiver pressure drop and cycle parameters on the overall exergy and cycle thermal efficiency was analysed. The results showed that, for all configurations, the overall exergy efficiency of the solarised systems achieved at maximum value between 700°C and 750°C and the optimum value is adversely affected by the solar receiver pressure drop. In addition, the optimum cycle high pressure was in the range of 24.2–25.9 MPa, depending on the configurations and reheat condition.

Modelling of oil shale retorting block using ASPEN process simulator

Abstract An integrated process model for the retorting block of an oil shale conversion process is presented. The model integrates only the key process operations such as drying/preheating and pyrolysis of raw oil shale, combustion of spent shale and sensible heat recovery from combusted shale. The flowsheeting package ASPEN has been used to achieve mass and energy balances around the process. Performance data for individual process units were generated using detailed reactor models developed previously.

Emissions of SO2 during batch fluidized bed combustion of Rundle retorted shale

Results are presented showing the existence of some mineral reactions affecting the emission of SO2 during the combustion of Rundle retorted shale in a batch fluidized-bed combustor. Evolution of SO2, CO2 and CO was observed while the sample was quickly heated in N2 to 820 °C. SO2 emission (< 5% of the total S in the sample) was the result of a reaction of pyrite with a high concentration of steam produced from the free moisture and clay-bound water. One-third of the CO2 release was from the decomposition of calcite. Pyrolysis of char and reduction of iron oxides by carbon produced the rest of the CO2 and CO. The combustion following the pyrolysis was characterized by a high molar COCO2 ratio and a long delay in SO2 emission. Combustion of char consumed initially all available oxygen in the feed gas and therefore delayed the combustion of pyrite/pyrrhotites.

Processing oil shales with heavy oil recycle

Abstract Recycle of heavy oil (>340 °C) to the retort, in order to crack/coke the oil to lighter fractions, was investigated as a means of producing shale oil of more desirable product slates. Conversion of heavy oil to light oil (