Desulphurisation Hemant Pandit, Ranjan agrawal

DTU Chemical Engineering Technical University of Denmark The wet FGD process CaCO 3 (s) + SO 2 (g) + 2H 2 O + ½O 2 → CaSO 4 2H 2 O(s) + CO 2 Major reactions (Kiil, 1998) ● Absorption of SO 2 ● Oxidation of HSO 3 - to SO 4 2- ● Limestone dissolution ● Gypsum crystallisation Important parameters ● Desulphurisation degree ● Gypsum moisture content ● Gypsum impurity content (limestone etc.) CHEC Annual Day, Courtesy of DONG Energy Wet Flue Gas Desulphurisation 1

DTU Chemical Engineering Technical University of Denmark Oxy-fuel combustion ● Substitution of fuel air with oxygen ● Flue gas recycle in order to control temperature/convective heat transfer ● Gas phase enriched in CO 2 & H 2 O ● Capture and compression of CO 2 Flue gas desulphurization ● Ensuring a clean product – i.e. transport and geological storage considerations ● Wet FGD before compression (traditional) ● As part of the compression (research stage) Courtesy of Vattenfall The oxy-fuel concept 2 CHEC Annual Day,

DTU Chemical Engineering Technical University of Denmark Fuel Processing

DTU Chemical Engineering Technical University of Denmark Fuel Processor

DTU Chemical Engineering Technical University of Denmark C + O 2 CO 2 C + H 2 O CO + H 2 C + CO 2 2CO CO + H 2 OCO 2 + H 2 CO + 3H 2 CH 4 +H 2 O Moving bed Fluidized bed Entrained bed BGL Shell Texaco KRW HT Winkler and many more Second generation Generic Types Gasification of solid fuels

DTU Chemical Engineering Technical University of Denmark Partial Oxidation C x H y + x/2 O 2 x CO + y/2 H 2 Advantages:  Any type of hydrocarbon  Direct Heat transfer Disadvantages:  Low H 2 production  Dilution of gas with N 2  Soot formation

DTU Chemical Engineering Technical University of Denmark Desulphurisation  Gas phase Desulphurisation ZnO + H 2 S ZnS (s) + H 2 O (g) 2 to 3 kg ZnO sufficient for one year Automobile operation  Liquid Fuel Desulphurisation Gasoline ppm 1-2ppm Sulphur For high sulphur Fuels hydro treatment followed by gas phase Desulphurisation Adsorption Chemical reaction

DTU Chemical Engineering Technical University of Denmark Conclusions  Presently liquid fuels like gasoline & Diesel which contain high aromatic content and sulfur are not very suitable for on board applications.  Availability of Methanol & Ethanol for fuel uses are inadequate.  For use of natural gas economic and environmental benefits are to studied in detail.  A multi fuel Reformer needs to be developed (For fuels with small range of C/H ratio).  Thrust areas for R&D Development of reactors/separators (Membrane) Indigenous Catalyst development