The purpose of the ZECOMIX (Zero Emission of Carbon with Mixed technologies) pilot plant is twofold. One is the production of hydrogen from conventional fuels (e.g methane and coal) by means of the Calcium Looping (CaL) process which is an high temperature gas solid reaction. The Ca based material used in ZECOMIX is low cost (<10 €/t) and has no impact to the environment and the human being. The other objective of the ZECOMIX is the study of the CaL process as thermochemical storage of heat. The main aim of the project is to demonstrate, through a series of modelling and experimental activities, the feasibility of an this innovative process for storage not only the solar energy but also the waste heat produce in high energy demand industries (e.g. steel making process and cement production).
The plant which has a TRL 6/7 (see figure 1) was presented in international research frameworks (e.g. CSLF, ZEP and EERA) as one of the advanced technological initiatives of the European and worldwide scientific community. One of the key advantages of this option which makes it a valuable route for gas decarbonisation or the heat storage is the low cost and wide availability of the feed material (a naturally occurring sorbent such as limestone or dolomite) and its high reactivity with CO2. In the CaL process, CaO is converted into CaCO3 by reacting with gaseous CO2, then the spent solid sorbent is regenerated in a calcination step (heat storage) at a temperature range from 800 to 850 °C leading to the release of the captured CO2 in a pure stream that can be sent to final storage. The heat is released during the successive reaction between CO2 and CaO (carbonation step) at 650 °C.
ZECOMIX is also composed of a 500 kWth steam/oxygen blown bubbling fluidised bed coal gasifier. The coal feed system was designed for a nominal load of 1.4 t/d of coal. The system includes a 2 m3 unit for coal storage, which allows the stationary operation of the gasifier for up to 36 hours, and two screws driven by an engine connected to an inverter. Finally, the clean syngas generated by the coal gasifier will fed a 100 kW micro turbine.
The novelty of ZECOMIX is the combination of well-known industrial processes (e.g. calcination for the clinker production, gasification and reforming of conventional fuels) for the production of H2 as energy carrier and the storage of solar power and industrial heat waste. The Ca based material used in ZECOMIX is low cost (<10 €/t) and has no impact to the environment and the human being.
Scientific environment (related and potentially available scientific and technical services at RI's location e.g. analysis, material preparation etc.)
Synthesis of high regenerable material for O2 carrying capacity and/or CO2 capture
Alternatively to modifying naturally occurring minerals to improve their properties there is also the option to develop completely new synthetic sorbents with tailored properties. ENEA is investigating the use of synthetic long life sorbent CaO/Ca12Al14O33 synthesised our laboratories which has been used for 1000 CO2 uptake / regeneration cycles under industrially relevant conditions. This material could be used as a support of O2 carrying phase (e.g. CuO);
Process intensification: integration of CaL technology with cement production process
In the field of process intensification a potential common area of interest is the integration of cement production process with a fluidised bed of CO2 acceptor to decarbonise flue gases leaving a rotary kiln. In the facility of ENEA is currently investigating the effect of CO2 presence during the calcination of limestone;
Developing of particle models for the study of simultaneous diffusion and reaction process in gas solid reaction
ENEA is active in developing a grain model which can be integrated in commercially relevant software tool for the simulation of CO2 capture systems (e.g. bubbling fluidised bed reactors).
ZECOMIX is supported by a set of analytical apparata composed of:
Micromeritics ASAP 2020N – Automatic physiosorption analyser for the evaluation of specific surface area and distribution of the pore in porous solid material
Micromeritics Autochem HP micro-reactor is an automated high-pressure catalyst and sorbent characterization system that is capable of preparing and analyzing samples at elevated pressures up to 68 atm and at temperatures up to 1100 °C. The instrument can perform a variety of experiments including pulse chemisorption, temperature-programmed reduction (TPR), desorption (TPD), oxidation (TPO). This micro-reactor, combined with a FTIR or gas chromatograph GC, can also be used to determine product yields and catalytic and sorbent activity under industrial conditions;
Mettler Toledo GC-200 thermo-gravimetric analyser, differential scanning calorimetry TGA-DSC – TGA-DSC records the change in weight of a solid sample when it is heated, cooled or dwelled at constant programmed temperature. Heat exchanged with the environment is also recorded during the analysis. The apparatus can be connected online to a FTIR spectrometer or gas chromatograph GC. Analysis of the decomposition products yields additional information about the investigated solid sample;
Varian 640-IR Fourier Transfer Infrared (FTIR) Analyzer – FTIR spectroscopy provides quantitative determination of a wide range of species. This enables us to interpret measurement curves collected from micro-reactor and TGA-DSC with greater accuracy;
Agilent 6850 Gas Chromatograph (GC) – Agilent GC is available for H2, N2, CH4, CO, CO2, H2S and equipped with an Electron Capture Detector (ECD).