Y. G. Son

Pulsed plasma process for the flue gas removal from the industrial incinerator using peak 200-kV, 10-kA pulse modulator

The electrical discharge process, especially the pulsed plasma discharge process can be applied to the removal of pollutant gases from industrial plants such as power generation plants and incinerators. Up to now, most of the study has been performed in a laboratory scale with short-term tests due to the lack of a reliable pulse modulator with a high average power. The pulsed corona discharge method shows encouraging results for the removal of NOx and SO2 gases based on smallscale experiments. A 120-kW high average power modulator for industrial applications of the pulsed corona process to remove flue gas has been designed and manufactured. It is one of the largest scale modulator systems in the world for treating NOx and SO2 simultaneously. Its design specifications are as follows: an average power of 120 kW, a peak voltage of 200 kV with a full width at half maximum (FWHM) of 500 nsec, a peak current of 10 kA, and a pulse repetition rate of 300 Hz. It is required to have long lifetime and high reliability for commercial plant application because the downtime for maintenance affects plant availability. A high-power, fast semiconductor switch, a magnetic-pulse-compression (MPC) switch, and a fast-pulse transformer are essential components to meet these requirements. The 120-kW high average power modulator has been installed and tested at an industrial incinerator plant with a gas flow of 50,000 Nm/Hr. This modulator was operated with pulses of up to 150 kV with 500-nsec (FWHM) pulse widths at a 240-Hz repetition rate in a plasma reactor. This paper presents the design details and operational test results. Especially, the dynamic operating characteristics of the MPC modulator combined with the non-thermal plasma reactor were measured, and the SO2 and NOx removal characteristics were analyzed.

Study of the TVS trigger geometry and the triggered vacuum conditions

This presentation focuses on the optimization of the trigger unit of a six-rod triggered vacuum switch. The different configurations of the trigger pin and of the trigger electrode have been considered to study the electric field distribution at the triple points of the unit embedded in the cathode. Electric field simulations with a planar and a circular head of the trigger pin in combinations with a convex-shaped and a concave-shaped trigger electrode have been done to optimize the field enhancement. The simulations were done with an applied trigger pulse voltage of Utrigger = 5 kV and with a discharge voltage for the main switch of Uswitch = 20 kV. The experimental values were Utrigger = 40 kV and Uswitch = 5 kV. The simulation results show that the combination of a circular trigger pin head and a concave trigger electrode yields the highest electric field of 9.6 ·106 V/m at the triple point. In-parallel experiments have been performed with those four trigger configurations. The results of the experiments, however, cannot yet be used to confirm the trend in the results of the field simulations.

Commissioning of L-band intense electron linac for industrial applications

An intense L-band electron linear accelerator is under construction at CESC (Cheorwon Electron-beam Service Center) for industrial applications. It is capable of producing 10-MeV electron beams with 30-kW average beam power. For high-power capability, we adopted 1.3 GHz, and the RF source is a 25-MW pulsed klystron with 60-kW average RF output power. The PFN-type modulator and the matched transformer provide 264-kV beam voltage with 230-A beam current to the klystron. The RF pulse length is 7 mus, and the repetition rate is 350 Hz. The thermionic E-gun generates 80-kV electron beams with pulsed 1.6 A. The pre-buncher, a single standing-wave cavity, is used before the bunching section, which is built-in with the regular accelerating section. The accelerating structure is a disk-loaded waveguide with a constant-impedance operated in the 2pi/3-mode. It is to be operated under the fully beam-loaded condition, where the beam power is maximum. The electron beams are accelerated within 6 mus since the traveling-wave filling time of the accelerating structure is almost 0.8 mus. In this paper, we present details of the accelerator system and commissioning results.

Current status of L-band electron accelerator for irradiation source

An intense L-band electron accelerator is designed and under development for CESC (Cheorwon Electron-beam Service Center) irradiation applications. It is capable of producing 10-MeV electron beams with average 30 kW. For an RF source, a Thales klystron is used with 1.3 GHz, pulsed 25 MW, and average 60 kW. The accelerator column, fabricated by IHEP in China, is operated with 2pi/3 mode traveling-wave under the fully-beam-loaded condition. The modulator was fabricated with inverter power supplies. The klystron was assembled to the klystron tank with pulse transformer. The high-voltage pulse test was conducted for the klystron tube. In this paper, we present design details of the accelerator and current status.

Average 120-kW MPC modulator for plasma de-NO/sub x//de-SO/sub x/ system

The pulsed corona discharge process shows the encouraging results for the removal of NO/sub x/ and SO/sub x/ gases based on small-scale experiments. The lifetime and the reliability of the system are major difficulties to realize this newly developed technology because the downtime for maintenance affects the plant availability. The combination of a high power solid-state switch with a magnetic pulse compressor (MPC) is a suitable scheme to meet these requirements. An average 120-kW MPC modulator has been constructed and tested with a plasma reactor for an industrial incinerator plant. The plasma reactor has wire-plate electrodes and can treat the gas of 50000 Nm/sup 3//Hr. This modulator can generate 150 kV pulses with 500 nsec (FWHM) pulse width, and 300 Hz repetition rate. This paper presents design details and the operational characteristics of the MPC modulator.