| 摘要 |
<p>PURPOSE:To prevent the scale formation, such as ammonium sulphate etc., in heat exchanger, by circulating untreated gas after preheating in untreated gas before preheating and rising to a specific temperature at the time of preheating untreated gas by heated already treated gas sent out from denitration reactor in the heat exchanger. CONSTITUTION:A part of the untreated gas 2A after preheating is circulated to the untreated gas A through the circulation line 8 at the time of preheating the gas A by the already trated gas 4 from the NH3 reducing process denitration reactor 1 in the heaat exchanger 5 and temperature of untreated gas before preheating is risen to that of not forming scaling matter, such as (acidic) ammonium sulfate etc. For example, about 30% of the gas A is circulated at the time when supply temperatue of the gas A t1=190 deg.C, SO3=7ppm and NH3=20ppm and also, scale formation is prevented making T1=225 deg.C, T2=333 deg.C, T3=370 deg.C and T4=235 deg.C.</p> |
