The Used of Aqueous Urea Solution in Reduction of Noxious Emissions in Bio Fuel Combustion System Using Selective Non-Catalytic Reduction

Mohamad Shaiful Ashrul Ishak,Mohammad Nazri Mohd Jaafar

doi:10.5539/mas.v5n4p30

Mohamad Shaiful Ashrul Ishak, Mohammad Nazri Mohd Jaafar

Open Access

https://doi.org/10.5539/mas.v5n4p30

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Abstract

Selective Non-Catalytic Reduction (SNCR) of nitric oxide was studied experimentally by injecting different concentrations of aqueous urea solution; urea and ammonia in a pilot-scale Bio-fuel fired tunnel furnace at 3-4 % excess oxygen level and with low ppm of baseline NOx ranged from 65 to 75 ppm within the investigated temperature range. The furnace simulated small-scale combustion systems where the operating temperatures are usually in the range of about 973 to 1323 K and NOx emission level remains below 100 ppm. NOx reductions were studied with the variation of different parameters such as injection temperature, residence time, Normalized Stoichiometric Ratio (NSR) of the reagent, carrier gas pressure, etc. A significant result shows that for NSR, at higher NSR, ammonia could give significant reduction of NOx at the investigated injection temperature. Meanwhile, for the effect of residence time, both aqueous solution shows that the NOx reduction increased with increase in residence time. Finally for the effect on injection temperature, both aqueous solution, up to a certain temperature NOx reduction continued to increase with increasing injection temperature and afterward the reduction decayed with further increase in temperature.

Highlights

Selective Non-Catalytic Reduction (SNCR) involves the injection of a reducing reagent into the combustion effluent at relatively higher temperatures to react with NOx
For the effect on injection temperature, both aqueous solution, up to a certain temperature NOx reduction continued to increase with increasing injection temperature and afterward the reduction decayed with further increase in temperature
The tests were performed in a range of Normalized Stoichiometric Ratio (NSR) from 1 to 4, temperatures from 973 to 1323 K and residence time for 815 mm of reactor. 5.1 Effect of Normalized Stoichiometric Ratio The Figure 2 shows the effect of normalized stoichiometric ratio on NOx reduction for 5% urea and ammonia solution at an injection temperature of 1093 K and NSR of 4

Summary

Introduction

Selective Non-Catalytic Reduction (SNCR) involves the injection of a reducing reagent into the combustion effluent at relatively higher temperatures to react with NOx. The reaction between NOx and NOx reducing agent occurs in a temperature window of 1144 to 1366 K. The reaction between NOx and NOx reducing agent occurs in a temperature window of 1144 to 1366 K This temperature window, the reagent might be oxidized resulting in the formation of additional NOx and below the window the rate of reaction becomes slow which may result in excessive ammonia slip (Rota, 2002). The temperature window ranges from 1199 to 1310 K. NOx reductions are lower and chemical consumption is higher as compared to Selective Catalytic Reduction (SCR) (Ishak and Jaafar, 2011). The urea may be stored as a solid or mixed with water and stored as a solution

NOx Reduction Using Aqueous Urea Solution

Results and Discussions

Conclusions