This article reports results from measurements of mainly submicrometer particles at the inlet and outlet of a newly designed industrial wet electrostatic precipitator (WESP) in a combined heat and power plant fueled with municipal solid waste. The measurements were carried out with dual electric low-pressure impactors in parallel at the precipitator inlet and outlet. In addition, measurements were carried out with traditional total dust filters, low-pressure impactors, a scanning mobility particle sizer, and an aerodynamic particle sizer. The measurements aimed to characterize the aerosol particles and measure the efficiency of the WESP with special attention to fine and ultrafine particles. In general, the WESP performance and response to varying conditions was found to be in line with predictions made for the design. The WESP featured a cooled collector surface, but based on the limited results, no conclusion could be drawn regarding any possible improvement from collector cooling. The characterization of the aerosol particulate matter was challenging because of fast fluctuations in particle concentration. Methodological considerations are pointed out, mainly regarding the SMPS and ELPI measuring systems.

The combustion of biomass creates ultra-fine particulate matter which is not precipitated by traditional multi cyclone technique, usually adopted on small scale plants. In Sweden the number of small bio fuelled plants is increasing and there is a need for cost effective means to precipitate the ultra-fine particles formed. One such technique may be electrostatic precipitation, but the economy of scale is a constraining factor for systems commercially available today. This paper describes field tests of a low cost electrostatic precipitator, ESP, including not only investigation of collection efficiency, but also measurement of charging effectiveness. The aim of the tests was to determine the potential for the low cost ESP design to form part of an electrostatic precipitation system for use on bio fuelled plants in the megawatt scale. The charges acquired by the particles have been measured using a low pressure cascade impactor, ELPI. Measurements of charges were carried out on particles escaping from the ESP. The results of the measurements of particle charges indicates that the method may correctly reflect the mean charge levels of particles of the different sizes usually found within the fine particle mode of flue gases from biomass combustion.

The combustion of biomass creates ultra fine particulate matter which is not precipitated by traditional multi cyclone technique, usually adopted on small scale plants. In Sweden the number of small bio fuelled plants is increasing and there is a need for cost effective means to precipitate the ultra fine particles formed. One such technique may be electrostatic precipitation, but the economy of scale is a constraining factor for systems commercially available today. This paper describes field tests of a low cost electrostatic precipitator, ESP, including not only investigation of collection efficiency, but also measurement of charging effectiveness. The aim of the tests was to determine the potential for the low cost ESP design to form part of an electrostatic precipitation system for use on bio fuelled plants in the megawatt scale. The charges acquired by the particles have been measured using a low pressure cascade impactor, ELPI. Measurements of charges were carried out on particles escaping from the ESP. The results of the measurements of particle charges indicates that the method may correctly reflect the mean charge levels of particles of the different sizes usually found within the fine particle mode of flue gases from biomass combustion.

Avsliljningstekniker för mindre biobränsleanläggningar, i storlek under 10 megawatt, har undersökts. Experiment i laboratorium och fältförsök har utförsts avseende elektrostatiska filter.

The performance of a full-scale ESP was studied at the Vattenfall AB oxyfuel pilot plant in SchwarzePumpe. The lignite-fired boiler has a 30 MWth top-mounted pulverized coal burner and was operated under conventional air combustion as well as oxyfuel combustion. The ESP was operated with varying numbers of fields in service and at different current/voltage settings. Particle number size distributionsdownstream the ESP were established on-line in the size range 0.015-10 μm, using an electrical mobility spectrometer and an aerodynamic particle sizer. The particle size distribution at oxyfuel operation was qualitatively very similar to the results obtained for air-firing. Gravimetric measurementsof total fly ash concentration showed outlet emissions below 5 mg/Nm3 when the ESP was operatedwith two fields in service at oxyfuel conditions.

The performance of a full-scale ESP was studied at the Vattenfall AB oxyfuel pilot plant in Schwarze Pumpe. The lignite-fired boiler has a 30 MWth top-mounted pulverized coal burner and was operated under conventional air combustion as well as oxyfuel combustion. The ESP was operated with varying numbers of fields in service and at different current/voltage settings. Particle number size distributions downstream the ESP were established on-line in the size range 0.015-10 m, using an electrical mobility spectrometer and an aerodynamic particle sizer. The particle size distribution at oxyfuel operation was qualitatively very similar to the results obtained for air-firing. Gravimetric measurements of total fly ash concentration showed outlet emissions below 5 mg/Nm3 when the ESP was operated with two fields in service at oxyfuel conditions.

This research considers three stage Electrostatic precipitators, diffusion charging and other novel techniques. Electrostatic Precipitators have shown to be both efficient and reliable on larger plants, however too costly to be an option for smaller plants. More stringent requirements on exposure of humans to particulate matter,especially fine particles, has put a pressure also on small plants to apply additional, costly filter technologies, to prevent emission of fine particulate matter. These more stringent requirements on small biofuel plants counteract the rational use of unrefined biomass resources. This research aims to investigate new principles to better adopt the Electrostatic precipitator technology to suit the specific fine particulate matter characteristic for biofuels, thus promoting the use of biofuel, simultaneously fulfilling more stringent emission requirements.