Transformation of low-rank coal to clean syngas and power via thermochemical route

An emerging gasification was proposed for the transformation of low-rank coal to clean syngas and electricity. The excess heat from char combustion was used to evaporate moisture in coal and to generate power via steam turbine generator. The simulation was developed in the Aspen Plus based on the proper thermodynamic model. The validation exhibited a good concurrence between the present model and the experiments under the same condition with the relative error <10% in the pyrolysis stage. The moisture content reduced the energy efficiency by ∼10% but increased the H₂ production by ∼50% which results in the increase of H₂/CO up to 10. The highest energy and exergy efficiencies (91% and 79%, respectively) was observed on the O₂ equivalence ratio and steam to ratio of 0.21 and 0.06, respectively. O₂ is an appropriate gasifying agent to produce syngas as the energy source, while steam gives high-quality syngas as the feedstock for chemical industries. The CO₂ emission of the proposed configuration is below 50 kg CO₂/GJ (half of the conventional coal combustion, ∼100 kg CO₂/GJ) when the fraction of char to combustor is less than 0.4.