Main results of the previous CO2freeSNG project

The proposed project shall continue the first CO2freeSNG project which focused already on medium scale Coal-to-SNG systems with emphasis on an innovative steam gasification technology the so-called Heatpipe reformer. The main results of the former CO2freeSNG project were:

1. The feasibility of the Heatpipe-Reformer technology in the 50-100 MW range

2. The tolerance of commercially available methanation catalysts against light tars 

3.  the severe impact of the gas cleaning technology on the process efficiency

A key challenge is still the gas cleaning: Scrubber technologies at -70°C to -40°C as applied by the Rectisol process guarantee highest purification of the syngas before the synthesis. However the experimental results showed that this pureness is not really needed for the methanation process since state-of-the-art catalysts accept significant loads of light tars (such as benzene, toluene, etc.). This tolerance allows higher scrubber temperatures and therefore higher process efficiencies. Figure 2 shows the impact of the scrubber technologies on the process efficiency. The auxiliary power increases with reduced temperatures.

The CO2freeSNG project proved the feasibility to provide SNG also on a medium-scale range of 50-500 MW using steam-blown fluidized bed gasification or oxygen-blown systems. The main challenge
of this approach is the CO2 removal in this scale range and a simplified integration of sulphur capture. The proposed project shall provide the proof-of-concept of a substantially simplified  process  chain that allows to simultaneously remove CO2, H2S, heavy tars, organic sulphur and excess steam by means of a single specially adopted pressurized water/carbonate scrubbing process with substantially increased process efficiency.Simulations in the preceding project indicated that such systems may capture CO2 and sulphur components most effectively at reduced costs and will finally allow to increase the total process efficiency by around 5 % pts. as shown in Figure 2 in case that the auxiliary power has to be provided with SNG.

 gas cleaning efficiencies

Comparison of Carbonate and Rectisol process, results from the previous CO2freeSNG project (AspenPlus - simulation)