Direktentschwefelung in Oxyfuel-Prozessen

  • Direct desulphurisation in oxyfuel processes

Kellermann, Arno; Kneer, Reinhold (Thesis advisor)

Aachen : Publikationsserver der RWTH Aachen University (2014)
Dissertation / PhD Thesis

Aachen, Techn. Hochsch., Diss., 2014


The realisation of coal based oxyfuel processes requires - as any other process based on a sulphur containing fuel - an efficient flue gas desulphurisation. Especially for the highly efficient membrane based process variants with hot flue gas recirculation as well as for fluidised bed combustions (independent of the kind of oxygen supply) direct desulphurisation with lime based sorbents is an interesting option. However, due to the increased partial pressure of carbon dioxide sorbents behave differently than in air fired processes. Therefore at first the theoretical determination of the conditions, which can be expected in oxyfuel furnaces, is deducted extensively. Subsequently, the experimental results are presented, which have been acquired by measurements in a fluidised bed reactor, which operates with synthetic flue gas. The influence of the following parameters on the direct desulphurisation in oxyfuel flue gases has been investigated: kind of sorbent, water content, sorbent particle size, temperature, carbon dioxide concentration, oxygen concentration and sulphur oxide concentration. Calcium carbonate, calcium hydroxide and calcium oxide have been used as sorbents. The sorbent particle diameter has been varied between < 50 µm and 355 µm, the temperature between 850°C and 975°C. Carbon dioxide and oxygen percentages from 50 vol% to 80 vol% and from 0.75 vol% to 4.5 vol%, respectively, have been studied. Sulphur oxide concentrations have been set between 250 ppm and 600 ppm. The influence of water vapour in the flue gas has been investigated by comparing measurements in dry and wet conditions. Results show that direct desulphurisation of oxyfuel flue gases with lime based sorbents is possible regardless of the increased carbon dioxide content. However, for an efficient operation some boundary conditions need to be adjusted to the different flue gas composition.