Evaluation of a Novel Cryogenic Oxygen Enrichment Method
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Uuden kryogeenisen hapenrikastusmenetelmän arviointi
The goal of this thesis was to study and evaluate the Nurmia oxygen enrichment process and to compare it with the conventional Linde-Frankl oxygen separation method. The study includes studying both processes, creating a simulation model of the Nurmia oxygen enrichment process, carrying out simulations with different oxygen product purities and the analysis of the simulation results with a comparison to literature values. The simulation model was assembled according to a basic apparatus of the Nurmia oxygen enrichment process. A sensitivity analysis was performed to verify the functionality of the model. In the simulation results the product purity per compressor power is higher than what is presented in literature, which is caused by partial idealizations in the sub-processes of the simulation model. Otherwise the simulation results corresponded well to the process values presented in literature. The Nurmia oxygen enrichment process is found to enable oxygen concentrate production with better efficiency than the conventional oxygen separation process Linde-Frankl. The power consumption of compression for Nurmia process varies from 75 to 111 kWh/ton of oxygen product depending on the chosen process configuration. Lowering the purity decreases the energy consumption. For the conventional Linde-Frankl process the power consumption from compression work is approximately 245 kWh/ton of oxygen product. The flexibility of the Nurmia process is also better because the Nurmia oxygen enrichment method allows producing oxygen product with purity from 50 mol-% to 99 mol-% depending on the process configuration. For Linde-Frankl process the oxygen content of product is 99.5 mol-% or more. A dynamic simulation model is recommended to be carried out next to investigate the functionality of the process start-up and process control. Also construction of a demo-scale plant is recommended to verify the simulation results.