Alexei Saveliev

Pulsed Corona Plasma Technology for Treating VOC Emissions from Pulp Mills

Under the DOE Office of Industrial Technologies Forest Products program various plasma technologies were evaluated under project FWP 49885 Experimental Assessment of Low-Temperature Plasma Technologies for Treating Volatile Organic Compound Emissions from Pulp Mills and Wood Products Plants. The heterogeneous pulsed corona discharge was chosen as the best non-equilibrium plasma technology for control of the vent emissions from HVLC Brownstock Washers. The technology for removal of Volatile Organic Compounds (VOCs) from gas emissions with conditions typical of the exhausts of the paper industry by means of pulsed corona plasma techniques presented in this work. For the compounds of interest in this study (methanol, acetone, dimethyl sulfide and ? -pinene), high removal efficiencies were obtained with power levels competitive with the present technologies for the VOCs removal. Laboratory experiments were made using installation with the average power up to 20 W. Pilot plant prepared for on-site test has average plasma power up to 6.4 kW. The model of the Pilot Plant operation is presented.

Reply on the Comments on “Initiation of Pulsed Corona Discharge Under Supercritical Conditions” by C. H. Zhang, J. M. K. MacAlpine, and H. Akiyama

Generation of plasma under supercritical conditions is of fundamental and applied interest. In this paper, the reduced electric fields required for breakdown of gaseous and supercritical carbon dioxide are comparatively analyzed for planar and coaxial cylindrical geometries. The indirect comparison of measured breakdown voltages suggests an essential change in the ionization mechanism both for uniform and nonuniform fields

Real Time Flame Monitoring of Gasifier and Injectors

This project is a multistage effort with the final goal to develop a practical and reliable nonintrusive gasifier injector monitor to assess burner wear and need for replacement. The project team included the National Energy Technology Laboratory (NETL), Gas Technology Institute (GTI), North Carolina State University, and ConocoPhillips. This report presents the results of the sensor development and testing initially at GTI combustion laboratory with natural gas flames, then at the Canada Energy Technology Center (CANMET), Canada in the atmospheric coal combustor as well as in the pilot scale pressurized entrained flow gasifier, and finally the sensor capabilities were demonstrated at the Pratt and Whitney Rocketdyne (PWR) Gasifier and the Wabash River Repowering plant located in West Terre Haute, IN. The initial tests demonstrated that GTI gasifier sensor technology was capable of detecting shape and rich/lean properties of natural gas air/oxygen enriched air flames. The following testing at the Vertical Combustor Research Facility (VCRF) was a logical transition step from the atmospheric natural gas flames to pressurized coal gasification environment. The results of testing with atmospheric coal flames showed that light emitted by excited OH* and CH* radicals in coal/air flames can be detected and quantified. The maximum emission intensities of OH*, CH*, and black body (char combustion) occur at different axial positions along the flame morexa0» length. Therefore, the excitation rates of CH* and OH* are distinct at different stages of coal combustion and can be utilized to identify and characterize processes which occur during coal combustion such as devolatilization, char heating and burning. To accomplish the goals set for Tasks 4 and 5, GTI utilized the CANMET Pressurized Entrained Flow Gasifier (PEFG). The testing parameters of the PEFG were selected to simulate optimum gasifier operation as well as gasifier conditions normally resulting from improper operation or failed gasifier injectors. The sensor developed under previous tasks was used to assess the spectroscopic characteristics of the gasifier flame. The obtained spectral data were successfully translated into flame temperature measurements. It was also demonstrated that the reduced spectral data could be very well correlated with very important gasification process parameters such as the air/fuel and water/fuel ratio. Any of these parameters (temperature, air/fuel, and water/fuel) is sufficient to assess burner wear; however, the tested sensor was capable of monitoring all three of them plus the flame shape as functions of burner wear. This will likely be a very powerful tool which should enable significant improvements in gasifier efficiency, reliability, and availability. The sensor technology was presented to the projectâx80x99s industrial partner (ConocoPhillips). The partner expressed its strong interest in continuing to participate in the field validation phase of GTIs Flame Monitor Project. Finally the sensor was tested in the PWR (Pratt & Whitney Rocketdyne) gasification plant located at GTIâx80x99s research campus and at the ConocoPhillips industrial scale gasifier at Wabash River Indiana. The field trials of the GTI Gasifier sensor modified to withstand high temperature and pressure corrosive atmosphere of the industrial entrain flow gasifier. The project team successfully demonstrated the Gasifier Sensor system ability to monitor gasifier interior temperature maintaining unobstructed optical access for in excess of six week without any maintenance. The sensor examination upon completion of the trial revealed that the system did not sustain any damage and required minor cleanup of the optics. «xa0less

Generation of Pulse Corona Discharge in Point-to-Plane Geometry Under Supercritical Conditions

Summary form only given. Generation of plasma under supercritical conditions is an unexplored area in plasma science. The known media of plasma applications include gas and liquid states with pressures from vacuum to atmospheric and above. Discharge development depends on the E/n ratio and the density of the media. In gaseous phase, the distance between the molecules is relatively large and electrical discharge can be achieved by using relatively low voltage. Concurrently, in liquid phase due to the densely packed molecules the required voltage for plasma generation is high. Some studies on plasma application for pollution control showed that small amount of dispersed liquid droplets increase the efficiency of the chemical utilization of the high energy electrons and reduce the required voltage at the same time. Supercritical fluid offers the unique advantage of having areas of low and high density that coexist in the fluid. This means that the discharge generated under these conditions starts in the low density gas like area where the required voltage for discharge initiation is low. Then the streamers rapidly propagate to the high density liquid like clusters, where the discharge propagation is controlled by mechanisms typical for the liquids. Our previous results on plasma generation under supercritical CO2 conditions in wire to cylinder pulsed power reactor suggest significant reduction of the breakdown voltage. At the same time the experiments conducted for point-to-plane configuration showed that the possibility for plasma generation extends far beyond the critical conditions (T=304 K, P=73.8 bar). In this paper we extend the knowledge on the dependence of the voltage required for plasma initiation on the pressure, temperature and density of the supercritical media. Furthermore, three different point-to-plane geometries are investigated to provide insight of the configuration influence on the plasma generation

Corona discharge under supercritical conditions

Summary form only given. Generation of non-thermal discharge in supercritical fluid environment is considered difficult due to high pressures and temperatures of the critical points of the fluids. This arises form Paschens law that suggests that increasing the process pressure leads to increase in the voltage required for plasma generation and, therefore, to enhanced operational cost. We have studied generation of corona discharge under supercritical fluid conditions near the critical point. The required voltage for this process is three times lower than the Paschens law prediction due to extensive cluster formation under the investigated conditions. However, there is a need of further investigation of the dependence of the breakdown voltage on the temperature and pressure of the supercritical fluid, so that this new process-generation of plasma under supercritical fluid conditions can be used for material science and pollutant removal applications. This promising new technology offers combination of the advantages of supercritical fluids as a unique reaction media due to its heterogeneous chemistry, enhanced heat and mass transfer with the benefits of the high energetic plasma state that is characterized with fast chemical reactions and high selectivity.