Preliminary Study On Combustion Characteristics Of Yellow Phosphorus Tail Gas

In the atmosphere of insisting sustainable development, carrying out clean production and energy conservation and emission reduction, the most direct and effective way to achieve pollution reduction and energy saving is resources utilization of yellow phosphorus tail gas in enterprises. At the present, yellow phosphorus tail gas as fuel has been recognized by majority of yellow phosphorus production enterprises. The research of combustion characteristics of yellow phosphorus tail gas plays an important role in utilization of yellow phosphorus tail gas. In this paper, starting with analyzing the composition of yellow phosphorus tail gas, design the experimental devices of yellow phosphorus tail gas. Then, by using the experimental device, proceed the field experiment in yellow phosphorus tail gas before and after catalytic oxidation. Meanwhile, using the software Fact-Sage, simulated the combustion distribution characteristics of combustion product of yellow phosphorus tail gas. It preliminary analysis the combustion characteristics of yellow phosphorus tail gas and provides the theoretical basis and experimental base for people.First of all, measure the gas composition in yellow phosphorus tail gas. According to the exhaust of combustible constituents in the tail gas, design the combustion experimental device, selecting the mode for diffusion combustion. The field experiment determines the combustion temperature distribution of yellow phosphorus tail gas and the components of raw gas and purified gas. The result shows that the optimal excess air coefficient a of raw gas is1.3, and the optimal excess air coefficient a of purified gas is1.25. At this point, the combustion temperature is the highest, reached to920degrees, and the height and wide of flame reaches250mm and30mm respectively, and the heat radiation area is the most extensive. The concentrations of CO, H2S and COS in flue gas decreased with the increase of excess air coefficient. However, the SO2concentration increased with the increased of excess air coefficient, but decreased with the excess air coefficients are greater than the optimal excess air coefficients. High level SO2concentration in the flue gas of burned raw yellow phosphorus tail gas, reached to1500milligrams per cubic meter. The flue gas will polluted environmental, and corrodes boiler material while the temperature below the dew point temperature. In the flue gas of purified yellow phosphorus tail, concentration of SO2is less than125milligrams per cubic meter.The software Fact-sage simulated the combustion thermodynamic properties of raw gas and purified gas, and analyzed the calculation data. The results show that, the distribution characteristics of material composition in combustion products are similar with the field experiment. The CO, O2, SO2, P2O5, H2S, PH3concentrations in the flue gas are related to the excess air coefficient. Under hypoxic conditions, the CO, H2S, COS, CS2, PH3concentrations in flue gas are higher. With the excess air coefficient increases, the concentration of combustible substance is decreased. Meanwhile, in the same excess air coefficient, the concentrations of SO2, P2O5are increased with temperature rising. In the high temperature condition, the CO2, H2O in fuel gas will take a decomposition reaction. The products and the P2O5, SO2react to PH3, H2S, COS, but the quantity is very few.According to analyze the relationship between the content of NOx and the content of O2, temperature, the result shows that, the generation of NOx is proportional to the content of O2and combustion temperature, and the rate of generation reaction of NO is higher than that of NO2. In the combustion process of raw yellow phosphorus tail gas, the reaction rate of NOx reaches the highest level when the excess air coefficient between1.2and1.3. But the reaction rate of NOx in the purified gas reaches the highest level when the excess air coefficient between0.9and1.1.