Analysis of the Effect of Catalytic Additives in the Agricultural Waste Combustion Process

The Effect of CaO on the CO and NOx Emission Characteristics of Fast-Growing Grass Combustion

Fast-growing grass is a biomass material with characteristics such as high temperature and drought resistance; rapid growth and development; and repeated germination and cutting. Therefore, it is a popular biomass fuel. It is required that the pollutants produced during the biomass combustion process are appropriately controlled. For this purpose, our study analyses the influence of combustion temperature and calcium oxide (CaO) on the nitrogen oxides (NOx) and carbon monoxide (CO) emission characteristics of fast-growing grass combustion using the biomass combustion flue gas analysis and testing platform. The results of our analysis revealed that CaO additive can simultaneously reduce the peak and total NOx emissions at 750 °C. Particularly, 5% CaO demonstrated a significant control effect on the NOx emission from the fast-growing grass combustion process, with a peak and total emissions reduction of 47.05% and 56.81%, respectively. In addition, with an increase in temperature, the CO emission curve attains a second peak higher than the first peak, and the peak and total emissions show a decreasing trend.

Effects of Structure and Composition of Adsorbents on Competitive Adsorption of Gaseous Emissions: Experiment and Modeling

Dangerous gases arising from combustion processes must be removed from the air simply and cheaply, e.g., by adsorption. This work is focused on competitive adsorption experiments and force field-based molecular modeling of the interactions at the molecular level. Emission gas, containing CO, NO, SO₂, and CO₂, was adsorbed on activated carbon, clay mineral, silicon dioxide, cellulose, or polypropylene at two different temperatures. At 20 °C, activated carbon had the highest NO and SO₂ adsorption capacity (120.83 and 3549.61 μg/g, respectively). At 110 °C, the highest NO and SO₂ adsorption capacity (6.20 and 1182.46 μg/g, respectively) was observed for clay. CO was adsorbed very weakly, CO₂ not at all. SO₂ was adsorbed better than NO, which correlated with modeling results showing positive influence of carboxyl and hydroxyl functional groups on the adsorption. In addition to the wide range of adsorbents, the main novelty of this study is the modeling strategy enabling the simulation of surfaces with pores of controllable sizes and shapes, and the agreement of the results achieved by this strategy with the results obtained by more computationally demanding methods. Moreover, the agreement with experimental data shows the modeling strategy to be a valuable tool for further adsorption studies.

Analysis of the Effect of Fe2O3 Addition in the Combustion of a Wood-Based Fuel

A comparative study was carried out of emissions from the catalytic combustion of pellets made from furniture board waste and pellets made from wood mixed with Fe₂O₃. The mass content of the Fe₂O₃ catalyst in the fuel was varied from 0% to 5%, 10%, and 15% in relation to the total dry mass weight of the pellets. The average flame temperature in the boiler was between 730 and 800 °C. The effect of the catalyst concentration in the fuel was analysed with respect to the contents of O₂, CO₂, CO, H_2, and NO_x in the flue gas and the combustion quality of the pellets in the heating boiler. Changes in the CO₂ content and the proportion of unburned combustible components in the combustion residue were assessed. It was established that an increase in the Fe₂O₃ content of the prepared fuels had a positive effect on reducing NO_x, CO, and H₂ emissions. However, the proportion of iron oxide in the tested fuel pellets did not significantly influence changes in their combustion quality. A strong effect of the addition of Fe₂O₃ on the reduction of the average NOx content in the flue gas occurred with the combustion of furniture board fuel, from 51.4 ppm at 0% Fe₂O₃ to 7.7 ppm for an additive content of 15%. Based on the analysis of the residue in the boiler ash pan, the amount of unburned combustibles relative to their input amounts was found to be 0.09-0.22% for wood pellets and 0.50-0.31% for furniture board waste pellets.