SYNGAS PRODUCTION BY MICROWAVE PLASMA JET AT ...
SYNGAS PRODUCTION BY MICROWAVE PLASMA JET AT ATMOSPHERIC PRESSURE: POWER SUPPLIED INFLUENCE H. S. Medeiros*, A. S. da Silva Sobrinho, G. P. Filho Plasma Processes Laboratory – Department of Physics, Technological Institute of Aeronautics, S.J. Campos, 12228-900, Brazil In this work a microwave (MW) plasma jet at atmospheric pressure was used to tar cracking/reforming investigation focus on synthesis gas (syngas) production such as CO, H2, and a few amount of CH4. In order to evaluate the best condition of operation, the influence of the power supplied on the syngas production from tar reforming was investigated. Argon, (argon + ethanol), and (argon +tar solution) plasma jet were produced by different values of power supplied (from 0.5 KW to 1.5 KW). The plasma was investigated by optical spectroscopy to each power and gas composition. The main species observed in the spectrum are Ar, CN, OII, OIV, OH, H2, Hβ, CO2, CO, and SIII. Currently, naphthalene is being used instead tar solution and the plasmas has been studied by optical spectroscopy and mass spectrometry.
Keywords: Plasma jet, syngas, power.
Introduction Now a day, scientific community is searching for new fuels able to replace fossil fuels with economic and environment gains and biofuel play a relevant rule, mainly for the transport sector. A major process to obtaining such type of renewable resource is biomass gasification. This process has as product a gas mixture containing CO, CH4, and H2 which is named synthesis gas (syngas) and also an undesirable high molecular organic species denominated tar, which must be removed. One way for tar removing without reducing the gas containing energy is using microwave plasma jet. Experimental part Fig. 1 shows the MW plasma jet apparatus. This consists of microwave system at 2.45 GHz, a quartz tube of 10 mm of external diameter, two heating system (i- to carrier gas pre-heating up to 250 ºC, and ii- to naphthalene heating up to 90 ºC), two control panels, and a 3 KW power supply. As a carrier gas were used argon and air. All experiments were made at atmospheric pressure. The optical analysis was performed with an optical emission spectrometer (Ocean Optics – model LIBS2500 plus) and to gas composition analysis was used a mass spectrometer (Max300-LG). Results and discussion
Optical measures were made focus on the main species in the tar reforming (CI, CN, SIII, OH, CO, and H2). Fig. 2 presents the behavior of the peak intensities of these species as a function of the power applied. The most surprising result that we can observe from this figure is about CN peak in the 1KW case. It is so higher in comparison with the other conditions. To the 0.75 KW and 1.5 KW conditions, the results are very similar which seems preferable to work at 0.75 KW of power supplied, saving energy. Besides this fact, the H2, CO, and OH formation is more intersting on
this power. Regarding the gas composition study, the preliminary results shows us that the MW plasma jet appears to be effective on the C10H8 cracking. However, more careful analyzes are still being held. (Ar + sol. de alcatrão) plasma CI (nm) CN (nm) SIII (nm) OH (nm) CO (nm) H2 (nm)
20
2
Absolute intensity (W/m .nm)
25
15
10
5
0
0,4
Fig. 1. Microwave plasma jet apparatus used to tar cracking and syngas production.
0,6
0,8
1,0
1,2
1,4
1,6
Power (KW)
Fig. 2. Main peaks observed on the tar reforming/cracking processes by microwave plasma jet.
Conclusions Microwave plasma jet at atmospheric pressure was used to tar cracking/reforming investigation focus on synthesis gas (syngas) production such as CO, H2, and a few amount of CH4. From the optical analysis we can conclude that the best power applied condition is 0.75 KW which is very helpful on the CO, H2, and OH formation and also saves energy. By the preliminary results of mass spectrometry is possible to conclude that MW plasma jet is a very powerful tool on the tar reforming/cracking. References
[1] ELLIOT, R.M.; NOGUEIRA, M.F.M; SOBRINHO, A.S.S.; COUTO, B.A.P.; MACIEL, H.S.; LACAVA, P.T.; Tar Reforming under a Microwave Plasma Torch, Energy&Fuels, 27 (2), PP 1174-1181, (2013).
Acknowledgement: FAPESP, CAPES.
Keywords: Plasma jet, syngas, power.
Introduction Now a day, scientific community is searching for new fuels able to replace fossil fuels with economic and environment gains and biofuel play a relevant rule, mainly for the transport sector. A major process to obtaining such type of renewable resource is biomass gasification. This process has as product a gas mixture containing CO, CH4, and H2 which is named synthesis gas (syngas) and also an undesirable high molecular organic species denominated tar, which must be removed. One way for tar removing without reducing the gas containing energy is using microwave plasma jet. Experimental part Fig. 1 shows the MW plasma jet apparatus. This consists of microwave system at 2.45 GHz, a quartz tube of 10 mm of external diameter, two heating system (i- to carrier gas pre-heating up to 250 ºC, and ii- to naphthalene heating up to 90 ºC), two control panels, and a 3 KW power supply. As a carrier gas were used argon and air. All experiments were made at atmospheric pressure. The optical analysis was performed with an optical emission spectrometer (Ocean Optics – model LIBS2500 plus) and to gas composition analysis was used a mass spectrometer (Max300-LG). Results and discussion
Optical measures were made focus on the main species in the tar reforming (CI, CN, SIII, OH, CO, and H2). Fig. 2 presents the behavior of the peak intensities of these species as a function of the power applied. The most surprising result that we can observe from this figure is about CN peak in the 1KW case. It is so higher in comparison with the other conditions. To the 0.75 KW and 1.5 KW conditions, the results are very similar which seems preferable to work at 0.75 KW of power supplied, saving energy. Besides this fact, the H2, CO, and OH formation is more intersting on
this power. Regarding the gas composition study, the preliminary results shows us that the MW plasma jet appears to be effective on the C10H8 cracking. However, more careful analyzes are still being held. (Ar + sol. de alcatrão) plasma CI (nm) CN (nm) SIII (nm) OH (nm) CO (nm) H2 (nm)
20
2
Absolute intensity (W/m .nm)
25
15
10
5
0
0,4
Fig. 1. Microwave plasma jet apparatus used to tar cracking and syngas production.
0,6
0,8
1,0
1,2
1,4
1,6
Power (KW)
Fig. 2. Main peaks observed on the tar reforming/cracking processes by microwave plasma jet.
Conclusions Microwave plasma jet at atmospheric pressure was used to tar cracking/reforming investigation focus on synthesis gas (syngas) production such as CO, H2, and a few amount of CH4. From the optical analysis we can conclude that the best power applied condition is 0.75 KW which is very helpful on the CO, H2, and OH formation and also saves energy. By the preliminary results of mass spectrometry is possible to conclude that MW plasma jet is a very powerful tool on the tar reforming/cracking. References
[1] ELLIOT, R.M.; NOGUEIRA, M.F.M; SOBRINHO, A.S.S.; COUTO, B.A.P.; MACIEL, H.S.; LACAVA, P.T.; Tar Reforming under a Microwave Plasma Torch, Energy&Fuels, 27 (2), PP 1174-1181, (2013).
Acknowledgement: FAPESP, CAPES.
