Abstract
The addition of limestone for sulphur retention in Fluidized Bed
Combustion (FBC) has been observed to influence the emission of
N2O, and in many cases a lower emission was observed. The
catalytic activity of a Danish limestone (Stevns Chalk) for
decomposition of N2O in a laboratory fixed bed quartz reactor was
measured. It was found that calcined Stevns Chalk is a very active
catalyst for N2O decomposition in an inert atmosphere compared to
bed material, i.e. a mixture of ash and sand. However, in FBC the
limestone is exposed to a mixture of gases, including CO, CO2 and
SO2, and sulphation of the limestone will take place. The
influence of these gases was investigated in the laboratory
reactor. The presence of 3 vol% CO increased the rate of N2O
destruction by a factor of 5 due to the catalytic reduction of N2O
by CO. The activity decreased with increasing CO2 concentration,
and uncalcined or recarbonated limestone had negligible activity.
Sulphation of the calcined limestone under oxidizing conditions
lowered the activity, however sulphidation under reducing
conditions showed that CaS is an active catalyst for the reduction
of N2O by CO. Without CO present a gas solid reaction between N2O
and CaS takes place and SO2 is released. Kinetic rate expressions
for the decomposition and reduction of N2O were developed.
| Original language | English |
|---|---|
| Title of host publication | Circulating Fluidized Bed Technology V, Proceedings of the Fifth International Conference on Circulating Fluidized Beds, May 28 to 31, 1996, Beijing |
| Place of Publication | Beijing |
| Publisher | Science Press |
| Publication date | 1997 |
| Pages | 338-343 |
| Publication status | Published - 1997 |
| Event | 5th International Conference on Circulating Fluidized Beds - Beijing, P.R. China Duration: 1 Jan 1996 → … |
Conference
| Conference | 5th International Conference on Circulating Fluidized Beds |
|---|---|
| City | Beijing, P.R. China |
| Period | 01/01/1996 → … |