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Laboratory test reactor for the investigation of liquid reducing agents in the selective catalytic reduction of NOx
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Image of FIG. 1.
FIG. 1.

Scheme of the reactor for the pulsation-free formation of water vapor by the reaction of H2 with O2 in N2. (A and E) glass wool, (B) flame arrester, (C and D) catalyst-coated monoliths, and (F) uncoated cordierite monolith to retain the glass wool.

Image of FIG. 2.
FIG. 2.

Left: Picture of the two-fluid nebulizer used for the spraying of liquid reducing agents into the catalytic reactor. The two-fluid nebulizer was originally designed for producing fine liquid sprays in ICP-MS instruments. Right: Nebulizer dimensions in mm (right).

Image of FIG. 3.
FIG. 3.

Technical drawing of the catalytic reactor for the investigation of liquid reducing agents with the attached heat exchanger for preheating the gas feed. The liquid reducing agents are dosed from the top of the reactor with a two-fluid nebulizer, shown in detail in Fig. 2. The spray cone formed by the nebulizer is illustrated in blue. T: thermocouples in the reactor head, upstream and downstream of the catalyst.

Image of FIG. 4.
FIG. 4.

Process scheme depicting gas dosing system, heating zones of experimental setup, integration of the spray reactor with connections and analytics.

Image of FIG. 5.
FIG. 5.

Aerosol quench and absorption apparatus for HPLC analysis of the reaction products: (Ref. 19) liquid quench of product gas (1), aerosol solubilizer (2), eluent reservoir (3), peristaltic pump (4), access for flushing (5), access to withdraw samples (6), water trap (7), gas pump (8), gas meter (9), glass frit P100 with a pore size of 40–100 μm (a), glass frit P40 with a pore size of 16–40 μm (b), and collection vessel (c).

Image of FIG. 6.
FIG. 6.

Test of the catalytic reactor for the SCR reaction. The influence of distance between the two-fluid nebulizer for urea solution (AdBlue) injection and catalyst frontal area on ammonia slip through the catalyst is shown in correspondence to the achieved NOx reduction (DeNOx) rates. Urea decomposes to ammonia in the hot reactor and on the catalyst surface. The more homogeneous the spray on the frontal area of the catalyst, the less ammonia slip is observed. The optimum result is obtained with NH3 gas, which is shown as reference. Catalyst: 2.5% V2O5-containing extruded catalyst (300 cpsi). T = 230 °C. GHSV = 19700 h−1. Feed gas: 1000 ppm NO, 5% H2O and 10% O2 in N2. AdBlue was varied from 10–40 μL/min, resulting in ammonia concentrations of 315–1260 ppm.

Image of FIG. 7.
FIG. 7.

Excerpt from Fig. 6 of distance-dependent NH3 slip/NOx reduction (DeNOx) plots at ammonia slip rates of up to 10 ppm.

Image of FIG. 8.
FIG. 8.

Spray cone radii at various distances derived from evaluation of NOx reduction rates (DeNOx) with urea solution (AdBlue). DeNOx values at 10 ppm NH3-slip could be related to the covered catalyst frontal area, since a relatively sharp separation between the spray cone and the surrounding gas could be assumed.


Generic image for table
Table I.

Power rating and set temperatures of the heating zones.

Generic image for table
Table II.

Calibration of the FTIR spectrometer for quantification of gaseous compounds.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Laboratory test reactor for the investigation of liquid reducing agents in the selective catalytic reduction of NOx