|Abstract or Summary
- Laminar entrained flow reactor (LEFR) was used to determine the effect of
temperature and residence time on the distribution of carbon, sulfur and nitrogen between
gaseous and condensed phase products from low temperature pyrolysis of kraft black
liquor. The operating furnace temperatures were between 400°C-600°C where the effect
of condensable organic and organic sulfur compounds may be important. The residence
times ranged from 0.3 to 2.0 seconds.
In the evolution of carbon as gases, an oxidizer was used to convert all oxidizable
components in LEFR effluent gas to carbon dioxide which was detected by an infrared
carbon dioxide meter. With this, measurement of total carbon in the gas phase, the fine
particles, and the char residue were made. The carbon yield in the gas phase increased as
residence time increased. The higher the temperature, the higher the carbon yield as gases
phase at each residence time. The carbon yield in the fine particles differed very little with
temperature at residence time below 1.1 seconds. At higher temperature, the carbon yield
in the fine particles is about the same at 500°C and 600°C, but lower at 400°C. The
carbon yield in the char residue decreased as residence time increased. The carbon yield in
the char residue at 500°C and residence time above 1.1 seconds was a little lower than at
temperature 600°C, due to an apparent loss of char at 500°C. The char yield at 500°C was
lower than expected based on the 400°C and 600°C data because of accumulation of
larger, more highly swollen char particles at the tip of collector at this temperature.
The average of the sum of carbon recovered as char residue, gases, and fine
particles was 96.2% at 600°C, 88.1% at 500°C, and 95.7% at 400°C. The main reason for
the poorer carbon recovery at 500°C was the loss of char particles which accumulated on
the tip of the collector. When the char yield at 500°C is increased so that the carbon
balance closed to 96%, the char yield, carbon yield, and sulfur yield at 500°C fell between
the values at 400°C and 600°C.
The sulfur yield in the char residue decreased as residence time increased. The
higher the temperature, the lower the sulfur yield in the char residue. The nitrogen yield in
the char residue also decreased as residence time increased.