Abstract
The addition of limestone for sulfur retention in FBC has in many
cases been observed to influence the emission of N2O. The
catalytic activity of N2O over calcined 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, and 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.
Sulfation of the calcined limestone under oxidizing conditions
lowered the activity, however sulfidation 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 decompostion and reduction of N2O were developed and used
to simulate the addition of Stevns Chalk to a 12 MWth CFBC burning
bituminous coal. The rate of N2O destruction was doubled when
limestone was added at a Ca/S ratio of 1.8 with 90%
desulfurization.
Original language | English |
---|---|
Title of host publication | Proceedings of the 14th International Conference on Fluidized Bed Combustion |
Volume | 2 |
Publication date | 1997 |
Pages | 953-966 |
Publication status | Published - 1997 |
Event | 14th International Conference on Fluidized Bed Combustion - Vancouver, Canada Duration: 11 May 1997 → 14 May 1997 |
Conference
Conference | 14th International Conference on Fluidized Bed Combustion |
---|---|
Country/Territory | Canada |
City | Vancouver |
Period | 11/05/1997 → 14/05/1997 |