High-Pressure Entrained-Flow Gasification: Validated Data from Pilot-Scale Experiments for Optimisation and Scale-up

High-pressure entrained-flow gasification (HP EFG) for the production of high-quality synthesis gas (H2+CO) from biomass or waste-based carbon sources can serve as one basic technology for the transition to a CO2-neutral circular economy. At KIT, basic research on HP EFG is carried out within the Carbon Cycle Lab (CCLab), which covers the process chain from pyrolysis and entrained-flow gasification to the synthesis of high-quality products such as basic chemicals, fuels or hydrogen. The extensive measurement equipment of the 5 MW pilot gasifier (HP EFG) at KIT enables for the detailed investigation of the gasification process over a wide range of feedstocks during operation as well as for the validation of simulation models for process optimisation and scale-up.
Validated fuel-specific key parameters are required for process evaluation, optimisation and scale-up. Most important for process efficiency is the lowest possible stoichiometric ratio and the resulting temperature of the synthesis gas in the gasifier. The temperature is limited downwards by the flow behaviour of the slag and the reactivity of the fuel. Both are difficult to determine at realistic process conditions in the laboratory; however, high temperatures, high pressure and a reducing atmosphere also limit the measurement possibilities in the gasifier. ... mehrThe calculation of the synthesis gas temperature, e.g. with an equilibrium model, is strongly influenced by the accuracy of the fuel analysis. Therefore, a balancing method for the HP EFG experiments was developed at KIT to obtain non-measurable variables, fuel-specific key parameters and to evaluate fuel analysis without measurements within the reaction zone and without interfering influence of the water quench [1].
As an example, the variation of the stoichiometric ratio for different fuels in the 5 MW HP-EFG experiment and in the equilibrium model shows the influence of fuel type and temperature (stoichiometry) on the yield of synthesis gas (CO+H2), see Fig. 1. The ASPEN equilibrium model provides the maximum achievable yield at full conversion for the same input and thus the optimisation potential. The yield decreases with increasing temperature due to the higher degree of oxidation and with decreasing temperature due to incomplete conversion.