Analysis and assessment of a hydrogen production plant consisting of coal gasification, thermochemical water decomposition and hydrogen compression systems

A novel hydrogen production plant is proposed, including a thermochemical water decomposition cycle, a pressurized entrained flow gasifier, a water gas shift membrane reactor, a cryogenic air separation unit, a hydrogen-fueled combined cycle for power production and a hydrogen compression system. The syngas produced by the pressurized entrained flow gasifier undergoes the shift reaction in the water gas shift membrane reactor. The stripping of hydrogen is done simultaneously with the shift reaction in the water gas shift membrane reactor to capture more hydrogen and increase the shift reaction conversion percentage. The remaining syngas is combusted in the Brayton cycle and power is produced through Brayton cycle gas turbine. The hot exhausts exiting the Brayton cycle gas turbine goes to the heat recovery steam generation unit where steam is produced. The generated steam goes to the copper-chlorine cycle to produce hydrogen. Part of the power generated by the Brayton cycle is used for the electrolysis reactor in the copper-chlorine cycle. Then, a small part of the hydrogen produced passes to the combined cycle to overcome the needed work rate by the components in the plant. The remaining larger portion of the hydrogen produced goes to the compression system to compress hydrogen to 700 bar for storage. The hydrogen production plant is developed and modeled in the Aspen Plus software package. Energy and exergy analyses are performed on the hydrogen production integrated system. The overall energy and exergy efficiencies of the proposed hydrogen production plant are found to be 51.3% and 47.6% respectively.