SCR COMBINED AIR PREHEATER SUITABLE FOR POST-SCR DENITRATION AND ANTI-CORROSION AND ANTI-BLOCKING METHOD

摘要

The present invention provides a combined air preheater after SCR denitrification, comprising a flue (1) and an air conduit (2) located downstream of the denitration unit and comprising a second wind section (3), a primary wind section (4), an ammonium hydrogen sulphation preventing section (5) and an ammonium hydrogen sulphate hardening section (6). Both the primary wind section 4, the ammonium sulfate condensation preventing section 5 and the ammonium hydrogen sulfate hardening section 6 are both phase-change heat exchangers. The phase-change heat exchanger includes an endothermic section 7 located in the flue, And a lifting conduit 9 and a down conduit 10 which are used to connect the heat absorbing section and the heat releasing section. The heat dissipation section 8 is higher than the heat absorption section 7, and a circulation medium is installed in the phase-change heat exchanger. The wall surface temperature of the ammonium hydrogen sulfate condensation preventing section 5 is higher than the exposure point temperature of the ammonium hydrogen sulfate and the wall surface temperature of the ammonium hydrogen sulfate hardening section 6 is lower than the solidifying point temperature of the ammonium hydrogen sulfate. This combined air preheater can prevent dust from entering the liquid ammonium hydrogen sulphate clogging the air front of the air preheater and effectively prevent corrosion of the air preheater due to the liquid ammonium hydrogen sulphate.