Plasma-based cleaning of exhaust gases of combustion Plasma based cleaning of exhaust gases of combustion(wp4)

Transcription

1 Plasma-based cleaning of exhaust gases of combustion Plasma based cleaning of exhaust gases of combustion(wp4) Eugen Stamate, Cornelia Iremiea, Technical University of Denmark, Denmark Indrek Jõgi, University of Tartu, Estonia Marcin Hołub, West Pomeranian University of Technology, Szczecin, Poland Michael Schmidt, Ronny Brandemburg, P Greifswald, Germany

2 Outline Main results using the NOx/SOx reduction reactor built at DTU: - NOx reduction - 3D simulations - Mixing schemes - FTIR diagnostics - Steep temperature gradient - Time dependence - Direct plasma treatment - VOC

3 NOx/SOx PlasTEP reactor built at DTU 6 m long reactor up to 250 SLM flue gas up to 100 g/h O 3 (air, O 2 ) NO, NO 2, O 3 sensors 7 sampling ports Controlled gas flows Gas and reactor heating Wet scrubber O 3 destroyer NOx up to ppm PC control The schematic design of the NO x reduction reactor.

4 NOx/SOx PlasTEP reactor built at DTU

5 NOx/SOx PlasTEP reactor built at DTU NO, NO 2, flows ozone generator ozone sensors flexible module

6 3D simulations for gas flow kinetics Geometrical details for the mixing chamber. Simulation results for NO, NO 2, O 3 and N 2 O 5 for J=4.

7 NO, NO 2 and O 3 as function of power The NO, NO 2, O 3 and O 3 R as a function of the ozone generator power, P, for 40 slm of dry air flow, 10 slm of ozonized air from the ozone generator and 0,027 slm of NO.

8 FTIR measurements Three FTIR spectra where (a) corresponds to a total flow of 50 slm, O 3 =2620 ppm, O 3R =790 ppm and P=287 W without NO x ; (b) 50 slm of hot air, 400 ppm of NO and 150 ppm of NO 2 at location P 1 without ozone; and (c) 40 slm of hot air, 10 slm of ozonized air, with O 3 =2000 ppm, O 3R =96 ppm, P=256 W, NO=1 ppm and NO 2 =240 ppm.

9 Chemiluminiscence, IR and UV absorption The evolution of different species as a function of O 3 using chemiluminiscence and UV absorption for NO x and O 3 R in the lower graph and using FTIR peaks for NO 2, N 2 O 5 and combined contribution (N 2 O 5 +HNO 3 ) in the upper graph.

10 Mixing schemes NO 2 and O 3 R as a function of O 3 at P 1 for all four mixing schemes for an air flow of 40 slm, ozonized air of 10 slm, slm of NO and initial values of NO=316 ppm and NO 2 =104 ppm (O 3 =0 ppm).

11 Mixing schemes - FTIR FTIR: NO 2 and O 3 R as a function of O 3 at P 1 for all four mixing schemes for an air flow of 40 slm, ozonized air of 10 slm, slm of NO and initial values of NO=316 ppm and NO 2 =104 ppm (O 3 =0 ppm).

12 Different ports The NO x reduction rate and O 3 R along the reactor (P 1 to P 5 ). The continuous and dashed lines correspond to 40 slm of dry air, 10 slm of ozonized air, with NO x =408 ppm for O 3 =0 ppm, O 3 =2687 ppm and T g =74 C and T g =63 C, respectively. The dotted line presents NO x and O 3 R for similar parameters except for slm of NO (514 ppm of NO x for O 3 =0 ppm), O 3 =2000 ppm and T g =21 C.

13 Different temperatures The NO, NO 2 and O 3 R as function of O 3 for a flue gas temperature of 74 C without nitrogen in the trap and at 16 C, with cooling in the trap and no flue gas heating for an air flow of 40 slm, ozonized air flow of 10 slm and 400 ppm for the initial NO x level.

14 Steep temperature gradient The design of the cooling trap. The NO x level as a function of time for 6 minutes (air flow 40 slm, ozonized air flow 10 slm, initial NO x level of 400 ppm, T g =75 C and O 3 =1800 ppm) and then the trap was cooled by adding liquid nitrogen at t=6 min while monitoring T g1 and T g2 and T g at P 1.

15 Time dependence Constant O 3, on-off NO, NO x at P 1 and P 5 for 50 slm dry air, 0,21 slm NO, NO x _on= 411 ppm, NO_on= 304 ppm. O 3 =1900 ppm, Power ozone generator = 256 W.

16 Direct plasma treatment

17 VOC treatment at DTU (Risø) - setup outlet reaction chamber plasma reactor gas inlet (N 2, O 2, NO) gas flow voc in pos. 1 voc in pos.2 VOC: toluene (C 7 H 8 ) position 1: indirect treatment: reactive species produced by plasma position 2: direct treatment of voc with plasma and reactive species Page 16

18 VOC treatment at DTU (Risø) - toluene Toluene removal vs. toluene flow / injection position Φ total = 80 L/min, P plasma 130 W, SED 156 J/L, T gas = 70 C Φ toluene = 1 L/min more toluene removed with indirect treatment Φ toluene = 2 L/min almost no difference found Page 17

19 VOC treatment at DTU (Risø) - NO x NO-NO 2 -conversion vs. toluene injection position Φ total = 80 L/min, P plasma 130 W, Φ toluene = 1 L/min higher NO-NO 2 -conversion with toluene injection before NTP small increase in NO x -content Page 18

20 VOC treatment at Risø - NO x NO-NO 2 -conversion vs. toluene flow toluene injection before NTP NO-NO 2 -conversion increasing with decreasing toluene flow smaller increase in NO x -content for Φ toluene = 2 L/min Page 19

21 Direct and indirect NO oxidation Ozone injection Oxidation of 200 ppm NO, 10 % O 2 and N 2 with ozone from synthetic air Comparable removal with direct plasma and ozone injection Catalyst (Fe 2 O 3 powder) had no effect on removal 20

22 Conclusions - NOx reduction by Ozone in dry flue gas can be done with an efficiency higher than 50% - A small size reactor for NOx/SOx reduction is available for research and development studies - Mixing has a small influence on the reduction rate - FTIR was successfully applied to investigate the oxidation process - A steep temperature gradient can improve the reduction rate - Time dependent reduction is feasible - Direct treatment resulted in higher NO 2 levels - Investigation of VOC removal can be performed