| 摘要 |
<p>PURPOSE:To prevent the high temp. corrosion of the supherheater tube of a recovery boiler, by a method wherein a part of the exhaust gas from the recovery boiler is brought into contact with a carbonate compound to increase a CO2-concn. while the CO2-concn. increased gas is blown into the firing furnace of the recovery furnace. CONSTITUTION:In a recovery boiler wherein a char bed 4 based on Na2SO4 discharged from the digestion process of pulp production is burnt in a firing furnace 1 to recover Na2S, a part of exhaust gas containing a large amount of SOx issued from an electric dust collector 7 is passed through a vessel 10 packed with a CaCO3 particle 9. Herein, if necessary, said gas is heated by a heater 11 to decompose Na2CO3 by the reaction of CaCO3 CaO+CO2 under a temp. condition of about 700 deg.C or more, pref., about 800 deg.C or more and further desulfurized by the reaction of CaO+SO3 CaSO4 to enhance the CO2-concn. in the exhaust gas while to reduce a Sox-concn. and the treated gas is blown into the firing furnace 1 from a secondary air port 2. The pipe surface of a superheater 3 is immobilized by this CO2 to prevent high temp. corrosion and the SOx concn. is reduced to reduce corrosion.</p> |
