Experimental Research On Reforming Of CH4into Hydrogen With Rotary Gliding Arc Driven By The Magnetic Field

As an efficient, clean and renewable energy, hydrogen is widely used in the fields of chemical industry, metallurgy, aviation and fuel cells et al. because of its high density of energy and high heat of combustion. More and more attention has been paid to product hydrogen by plasma; in this paper we research the rotary gliding arc driven by the magnetic field which has a dual character of thermal and non-thermal plasma. It has a high efficiency of energy transformation and inexpensive cost both from devices and operations. The gliding arc discharge plasma has a favorable foreground in the practical production as a new hydrogen production technology.We analyzed the electical parameter of rotary gliding arc driven by the magnetic field, and researched the waveforms of voltage and current under different carrier gas such as nitrogen, air, oxygen, and analyzed the effect of the flow field and magnetic field on the gliding arc by changing the flow rate of carrier gas and the strength of magnetic field. The result suggested that magnetic-drive could not only raise the rotary speed of the plasma gliding arc but enlarge the contact area between the plasma and the flow field; voltage and current of the gliding arc was most stable when the air was used as carrier gas, and the fluctuation cycle of voltage was3.5-4.4ms. The breakdown voltage of the arc was lower than800V when oxygen was used as carrier gas; when the gliding arc rotated continuously, the average voltage was lower than500V and the average power was95.8W, which was lower than other carrier gas. The movement of the arc was studied by using high-speed photography technology. According to the change of the magnetic intensity, we analyzed the form of the arc and found out that rotary gliding arc appeared to a double-arc in a low magnetic intensity, and the arc wouldn’t be broken when magnetic intensity was high, but it would jump from one point of the cathode to another, and the speed was approximately equal. While the study found that the jump frequency of electric arc shock is approximately the same as waveform of voltage, it can be inferred that the waveform of voltage has relatively fixed cycle because of the arc electric shock jump in a certain cycle.The flnent software was used to simulate the flow field of the reactor, and calculate the tangential velocity of airflow in the gliding arc reaction zone. The analog value of was available according to the stress analysis, and the study found that the analog value of rotation frequency is higher than the actual value, it is explained that the resistance of airfow is three-dimensional, and the arc would suffer more resistance of airflow in the actual process.In the paper we used the magnetic rotating gliding arc reactor to product the hydrogen by methane, and used the nitrogen or air as auxiliary gas. We researched on the influnce of the gas flow direction, the ratio of raw materials and other parameters of the arc current, and the study found that the effect of hydrogen production was obviously better when the inner electrode is postive. When the inner electrode is positive, n (CH4):n (N2)=0.4, the conversion rate of methane is highest,41.2%; the selectivity of hydrogenis decreased with ratio n (CH4):n (N2). When the air as auxiliary gas, methane is not only cracking reaction occurs, and also partial oxidation reaction; With increasing of excess air coefficient, hydrogen selectivity would increase first and decrease after, and the experiment show that a bit excessive oxygen would be benefit for increasing the hydrogen selectivity.