Ma Xiaoqian

Decomposition Characteristics and Kinetics of Microalgae in N2 and CO2 Atmospheres by a Thermogravimetry

The thermal degradation characteristics of microalgae were investigated in highly purified N2 and CO2 atmospheres by a thermogravimetric analysis (TGA) under different heating rates (10, 20, and 40°C/min). The results indicated that the total residual mass in CO2 atmosphere (16.86%) was less than in N2 atmosphere (23.12%); in addition, the kinetics of microalgae in N2 and CO2 atmospheres could be described by the pseudo bicomponent separated state model (PBSM) and pseudo-multi-component overall model (PMOM), respectively. The kinetic parameters calculated by Coats-Redfern method showed that, in CO2 atmosphere, the apparent activation energy ( ) of microalgae was between 9.863 and 309.381u2009kJu2009mol−1 and the reaction order ( ) was varied from 1.1 to 7. The kinetic parameters of the second stage in CO2 atmosphere were quite similar to those in N2 atmosphere.

Kinetic modeling of NOx reduction with by-product gases reburning

The surplus by-product fuels from steel plants, coke oven gas (COG), blast furnace gas (BFG), and Linz-Donawitz Converter Gas(LDG), can be used as the reburn fuel to lower NOx emission. Kinetic simulations were carried out to investigate the NOx reduction characteristic by these gases and their mixtures. BFG and LDG are primarily non-hydrocarbon fuels, which have a NOx reduction potential of 21–36% at the highest reburning temperature. Their NOx reduction potential monotonously increase with temperature and reburn fuel fraction. At similar conditions, COG can remove 87% of the nitric oxide and there is an optimum value for temperature and reburn fuel fraction to achieve the maximum NOx reduction. Conversion of NO to N2 in the reburn zone of a high HC gas proceeds primarily through the following sequence: CHi+NO→HCN+…→NHi+…→N2. A parameter study of the reduction ability of the COG/BFG mixture gas indicates that the optimum air/fuel ratio depends on the proportion of mixture.