Design av försöksanläggning för trycksatt rökgasrening vid oxy-fuelförbränning

Detta är en Kandidat-uppsats från Chalmers tekniska högskola/Institutionen för energi och miljö

Sammanfattning: Reducing the CO2-pollution, resulting from the combustion of fossil coal for energyproduction, is important to affect environmental changes. One way to achieve a reductionis to use the oxy-fuel technology. The technology uses O2 and re-circulated flue gasduring the combustion which results in a flue gas mainly consisting of CO2. The flue gascould then be compressed and stored without environmental effects. A problem thatfollows from the compression is the risk of acidification in sensitive parts of the process.Acidification can occur because of reactions following from the contact of condensedwater and sulphur- and nitrogen-oxides which are also present in the flue gas.This report compiles and evaluates the basis of a scientific unit with the purpose ofexploring the possibilities of extracting impurities of SOx and NOx from the flue gases.The dimensions of the unit are based on basic conditions, defined for an existing oxy-fuelprocess at Chalmers, and on the results of computer modelling. The computer modelssimulates chemical reactions in a gas phase reactor and in a two-phase reactor wherethe extraction of impurities is achieved by absorption. In addition to this, a researchon possible, compatible measuring tools is done.To create the right conditions for extracting the impurites the flue gas has to be compressedto between 10 and 16 bars and cooled down to a temperature of 40◦C. Theseconditions are necessary for oxidizing NO to NO2 and other water-soluble nitrogencompounds, which reacts efficiently with water. The oxidation of NO to these nitrogencompounds occurs efficiently in a gas phase reactor of the size 10 liters and with residencetime of 120 seconds. The final step is the extraction of the impurities where SOxand NOx are absorbed by water. The absorbtion occurs efficiently in a 10 liter twophasereactor at low temperatures and high pressures. To prevent acidification fromoccuring in sensitive parts of the process, it’s necessary to dry the flue gas before thecompression, in order to minimize the condensate. A new system of measuring toolswhich are compatible with the type of measurements needed is required.

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