Reduction characteristics of NOX emissions by optimal urea injection rate in a LPG steam boiler with urea-SCR reactor
The aim of this study is to develop the urea-SCR reactor aftertreatment system for reducing NOX emissions in a LPG steam boiler. The urea-SCR system utilizes ammonia converted from 17% aqueous urea solution injected in front of the SCR catalyst as a reducing agent for reducing NOX emissions. In this study, NOX emissions and exhaust gas temperatures according to boiler load were measured and compared with before and after urea injection in a LPG steam boiler with urea-SCR reactor. Also, the equivalence ratio, urea injection rate, ammonia slip and NOX conversion rate relative to boiler load were investigated. The equivalence ratio is different by changing the fuel consumption rate or intake air rate. In this experiment, the average equivalence ratio is calculated by changing only fuel consumption rate while the intake air rate is constantly fixed at 25,957.11 cm3/sec. The average equivalence ratios are 1.38, 1.11, 0.81 and 0.57 when boiler loads are 100, 80, 60 and 40%. In this experiment, NOX conversion rates are calculated by 89, 85, 77 and 79% in cases of the boiler loads of 100, 80, 60 and 40%. NOX conversion rate is raised with increasing urea injection rate, and NH3 slip is boosted at the same time. Consequently, the optimal urea injection rate for the respective boiler load should be determined by considering NOX conversion rate and NH3 slip simultaneously. In this study, the urea flow rates of 230, 235, 233 and 231 mg/min are injected at the boiler loads of 100, 80, 60 and 40%, and the final NH3 slips are measured by 8.48, 5.58, 11.97 and 11.34 ppm at the same conditions.
High Combustion Temperature for the Reduction of Particulate in Diesel Engines
Experiments on the effects of temperature T and equivalence ratio Φ on soot formation at high pressures up to 5 MPa were conducted. Discussion of the trajectory in relation to both soot and NO formation region gives suggestion of a possibility of high temperature ― rich mixture combustion to reduce particulate formation in diesel engines
The effect of temperature on soot formation in premixed flames
Abstract Soot production in atmospheric pressure, laminar premixed flames of toluene and decalin was studied by varying the composition of the fuel/O2/N2 mixture. As the O 2 (N 2 + O 2 ) ratio was increased, the onset of sooting occurred at higher fuel O 2 ratios and at higher calculated adiabatic flame temperatures. Temperatures measured using two-wavelength emission pyrometry, however, showed that the flame temperatures at the soot thresholds were constant for each fuel (1750K for toluene and 1720K for decalin). Soot volume fractions were also measured, using a multiwavelength laser extinction technique, as functions of equivalence ratio, O 2 (N 2 + O 2 ) ratio, and experimental flame temperature. The plateau soot volume fractions for each fuel were found, at any given value of the measured flame temperature, to be independent of the fuel O 2 and the O 2 (N 2 + O 2 ) ratios, over the range of variation of these parameters studies; they were dependent only on the flame temperature.