Zecomix experimental platform

Zecomix facility, located at ENEA Research Centre of Casaccia, near Rome, is a very flexible plant, in which more components can be tested separately or connected together. The main objective of the plant is to test some important phases of Zecomix cycle (Zero Emission Coal Mixed Technology), an high efficiency cycle that combines two different systems: the Zero Emission Coal gasification, characterized by an advanced coal gasification and high temperature decarbonisation based on calcium oxide sorbent,  and the Zero Emission Combustion TeChnology based on Hydrogen-fuelled internal combustion turbine cycle proposed by different authors in the framework of worldwide hydrogen research programs.

The plant produces 100 kWe electric power by means coal gasification with CO₂ capture for H₂ production and combustion in micro turbine; its main components are:

• a 50 kg/h coal atmospheric fluid bed gasifier, working with steam and oxygen, with a preliminary internal desulphurization by means of dolomite injection;
• a fluid bed decarbonator/calcinator reactor filled with a sorbent made by a mix of calcium oxide pellets and a catalyser; the aim of this component is to separate the CO₂ from coal syngas for end uses such as power generation and hydrogen storage. One of the basic ideas is to use calcium-based solid sorbents in a fluidised bed that will enhance the hydrogen content in the synthesis gas as well as capture of the carbon dioxide by means an adsorption process on the surface of porous solid. The separation process is based on the non-catalytic exothermic reaction: CO₂ (g) +  CaO (s)  →  CaCO₃ (s).

Studies on CO₂ absorption have demonstrated that calcite and dolomite are interesting as parent-sorbent for high-temperature CO₂ capture.
The solid sorbents have to be chosen in such a way as not to compromise their structural properties and capacity as CO₂-acceptor through the reaction-regeneration cycles.

The reactor works in more different phases:

• a first calcination phase in which an initial charge of dolomite (medium diameter of 200 micron) will be calcined to generate the calcium oxide;
• a second phase in which a suitable flow rate of hydrogen and nitrogen is introduced into the reactor:

1. to clean up the reactor itself;
2. to control the temperature of the bed;
3. to perform the reduction of the catalizer mixed with the sorbent;

• and finally the carbonation phase in which the CO2 rich syngas is introduced into the reactor within steam and natural gas to perform syngas decarbonisation.

• A clean-up syngas system characterized by a three stages scrubber to cooling and depolverize syngas before its use in micro turbine;
• a mixing gas station, to produce a syngas to test the decarbonizer reactor without gasifier working;
• a H₂ compression and cooling/dryer system, to rise the pressure at the operative value of the micro turbine (6 bar);
• a 100 kWe micro turbine test bench, that consists of a Turbec model, in which some modification to combustion chamber are made by Ansaldo to work with H₂ and steam;
• a 200 kWt steam generator, to produce steam for gasifier (20-40 kg/s), for decarbonator reactor (80 – 120 kg/s) and for micro turbine (70 – 90 kg/s) as diluent of H₂ at the inlet.

                
The first part of the research project is aimed at testing the single component, in particular the gasifier and the decarbonizer reactor.

The second part of the activities is focused on the integration of the different processes: syngas  production by coal gasification and its following decarbonisation and utilization in micro turbine combustion chamber.

The activities will be distributed in the next three years and involve ENEA, Ansaldo Energia and the most important Italian Universities.