Gliding arc triggered microwave plasma arc at atmospheric pressure for coal gasification application

Abstract

Plasma torch is device that efficiently converts electrical energy in to thermal energy for various high temperature applications. The conventional plasma torch comprises of consumable electrodes namely anode and cathode electrodes. The replacement of these electrodes is a complex process owing to its cooling and process shut down requirements. However, microwave plasma arc is electrode-less plasma arc system that is an alternative method to conventional arc technology for generating plasma arc. In this technique, microwave power is efficiently coupled to generate plasma arc by using the property of polar molecule to absorb microwave power. The absorption of microwave power is in form of losses due to intermolecular friction and high collisions between the molecules. This is an efficient method because all microwave power can be absorbed by plasma arc. The main feature of microwave plasma arc is its large uniform high temperature column which is not possible with conventional arc discharge methods. Such type of plasma discharge is very useful in applications where sufficient residence time for treat materials is required. Microwave arc does not require any consumable electrodes and hence, it can be operated continuously that makes it very useful for hazardous effluent treatment applications. Further, microwave cannot ionize neutral particles at atmospheric pressure and hence, a gliding arc is initiated between two thin electrodes in the cavity by applying very low power high voltage (3kV) AC source. In this report, the method for generating microwave arc of 1kW power using commercial microwave oven is elaborated.

Recent Progress on Hydrogen-Rich Syngas Production from Coal Gasification

“…Jain et al [31] proposed a novel microwave plasma arc triggered by a gliding arc for coal gasification, where the plasma arc efficiently absorbs and reflects all the power with an energy efficiency of up to 100%, and the radiation is completely avoided through proper shielding of the quartz tube. Uhm et al [86] developed a high-power steam plasma for the gasification process.…”

“…Conventional gasification, e.g., fixed bed, fluidized bed, and entrained flow bed technologies, are technically mature, and they have achieved large-scale industrial applications [18,23]. To further improve energy conversion efficiency, obtain hydrogen-rich syngas, and reduce CO 2 emissions, a series of relatively new gasification technologies have been investigated, including supercritical water gasification, plasma gasification, chemicallooping gasification, and decoupling gasification [13,[24][25][26][27][28][29][30][31]. Underground coal gasification is also viewed as a promising new technology for efficient conversion and utilization of coal [32][33][34].…”