• Energy Research
• 2016-2025close

A techno-economic analysis of a natural gas combined cycle integrated with a pre-combustion CO2 capture process based on the Ca-Cu process has been carried out. An extensive calculation of the balances of the entire power plant has been done, including the results obtained from a 1-D pseudo homogeneous model for the fixed bed reactors that compose the Ca-Cu process. Moreover, a methodology developed by the authors is here presented for calculating the cost of the electricity produced and of the CO2 avoided. This methodology has been used to perform the economic analysis of the Ca-Cu based power plant and to optimize the size of the Ca-Cu reactors and the pressure drop in critical heat exchangers. An electricity cost of 82.6 €/MWh has been obtained for the Ca-Cu based power plant, which is 2.2 €/MWh below the benchmark power plant based on an Auto Thermal Reformer with an MDEA absorption process for CO2 capture. The improved performance of the Ca-Cu based power plant in terms of electric efficiency and reduced capital cost expenditure is the reason for the reduced electricity costs. Moreover, a lower cost of CO2 avoided is also obtained for the Ca-Cu plant with respect to the benchmark (80.75 €/tCO2 vs. 85.38 €/tCO2), which features 89% of CO2 capture efficiency.

From a permeability and selectivity perspective, supported thin-film Pd–Ag membranes are the best candidates for high-purity hydrogen recovery for methane-hydrogen mixtures from the natural gas grid. However, the high hydrogen flux also results in induced bulk-to-membrane mass transfer limitations (concentration polarization) especially when working at low hydrogen concentration and high pressure, which further reduces the hydrogen permeance in the presence of mixtures. Additionally, Pd is a precious metal and its price is lately increasing dramatically. The use of inexpensive CMSM could become a promising alternative. In this manuscript, a detailed comparison between these two membrane technologies, operating under the same working pressure and mixtures, is presented. First, the permeation properties of CMSM and Pd–Ag membranes are compared in terms of permeance and purity, and subsequently, making use of this experimental investigation, an economic evaluation including capital and variable costs has been performed for a separation system to recover 25 kg/day of hydrogen from a methane-hydrogen mixture. To widen the perspective, also a sensitivity analysis by changing the pressure difference, membrane lifetime, membrane support cost and cost of Pd/Ag membrane recovery has been considered. The results show that at high pressure the use of CMSM is to more economic than the Pd-based membranes at the same recovery and similar purity.

In this work, the oxidation reaction of high loaded CuO-based materials was investigated under atmospheric and pressurized conditions. The oxygen transport capacity of the materials was firstly tested in the TGA and no losses greater than 5% were observed along 100 oxidation/reduction cycles. The kinetic parameters governing the oxidation reactions of the selected CuO-based materials were determined using a shrinking core model with chemical reaction control. The experimental results suggested that a SCM with chemical reaction control is able to predict the oxidation conversion of high loaded CuO-based materials in powder and pellet form. On the other hand, the effect of total pressure on materials reactivity was analyzed. The kinetic parameters obtained under atmospheric conditions were applied to fit the experimental data obtained under pressurized conditions. The results confirmed that the pressure has not an important effect on the oxidation kinetics of high loaded CuO-based materials and the parameters obtained at atmospheric pressure can be applied to study the oxidation under pressurized conditions.

Abstract To enable the investigation of the hydrodynamics of gas–solid fluidized bed reactors at high-temperatures and reactive conditions, a new non-invasive experimental technique has been developed, based on the extension of Particle Image Velocimetry (PIV) coupled with Digital Image Analysis (DIA) using dedicated high-temperature endoscopes for image recording and laser illumination. The new endoscopic-laser PIV/DIA technique (ePIV/DIA) allows to determine simultaneously information from the emulsion and bubble phase with high spatial and temporal resolution in a pseudo-2D columns. The ePIV/DIA technique with single-source laser illumination has first been thoroughly validated at cold-flow conditions by comparison with a standard PIV/DIA technique with LED-illumination, showing very good agreement of the results in terms of particle velocity and solids mass flux profiles. The technique has subsequently been applied to fluidized beds in the bubbling fluidization regime at elevated temperatures to demonstrate its unique possibilities to measure detailed bed hydrodynamics at elevated temperatures.

Global warming, climate change, fossil fuel depletion and steep hikes in the price of environmentally friendly hydrocarbons motivate researchers to investigate CO2 hydrogenation for hydrocarbons production. However, due to the reaction complexities and varieties of produced species, the process mechanism and subsequently estimation of the kinetic parameters have been controversial yet. Therefore, estimating the kinetic parameters using Artificial Bee Colony (ABC) and Differential Evolution (DE) optimization algorithms based on Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism is proposed as a possible remedy to fulfil the requirements. To this end, a one-dimensional heterogeneous model comprising detailed reaction rates of reverse water gas shift (RWGS), Fisher-Tropsch (FT) reactions and direct hydrogenation (DH) of CO2 is developed. It is observed that ABC exhibiting 6.3% error in predicting total hydrocarbons selectivity is superior to DE algorithm with 32.9% error. Therefore, the model employed the estimated kinetic parameters obtained via ABC algorithm, is exploited for products distribution analysis. Results reveal that maximum 73.21% hydrocarbons (C1–C4) selectivity can be achieved at 573 K and 1 MPa with 0.85% error compared to the experimental value of 72.59%. Accordingly, the proposed model can be exploited as a powerful tool for evaluating and predicting the performance of CO2 hydrogenation to hydrocarbons process.

This work investigates the full process design of a natural gas combined cycle integrated with a packed-bed reactor system where a hydrogen rich gas is produced with inherent CO2 capture based of the CaO/CaCO3 and Cu/CuO chemical loops. The different stages of this Ca-Cu process were modelled with a dynamic 1D pseudo-homogeneous model, proposing a novel reactor configuration allowing to achieve carbon capture efficiency close to 90%. Process simulations of the whole power plant resulted in electric efficiencies of around 48%LHV and SPECCA of 4.7 MJ/kgCO2.