DIRECT OBSERVATION OF ALKALI VAPOR RELEASE DURING BIOMASS COMBUSTION AND GASIFICATION .2. BLACK LIQUOR COMBUSTION AT 1100 DEGREES-C

This study details the first application of molecular beam mass spectr ometry to investigate the release of sodium, potassium, sulfur, and ch lorine during black liquor combustion, Two samples, black liquor with 37.1% dry solids and a sample of dry black liquor solids, were combust ed in a quartz-tube reactor at 1100 degrees C in 5% O-2 in helium, The gaseous black liquor combustion products, including alkali metal salt s, were monitored continuously and in real time during the combustion event with a molecular beam mass spectrometer (MBMS). Combustion of th e dry black liquor solids occurred in multiple phases distinguished as a devolatilization phase and a char combustion phase that was arbitra rily divided into three separate phases, Combustion of the wet black l iquor samples occurred in two phases, namely, a combination of water e vaporation and devolatilization, and char combustion, NaCl was the mos t abundant gas-phase alkali-metal-containing species measured during b lack liquor combustion, The experimental results showed evidence that gas-phase NaOH was also formed during combustion of both black liquor samples. In addition, gas-phase Na2SO4 was observed during combustion of the dry black liquor solids.