Jukka Hautanen

Electrostatic Precipitator Penetration Function for Pulverized Coal Combustion

ABSTRACT The penetration of fly ash particles through an electrostatic precipitator (ESP) was measured as a function of particle size in the range of 0.02–0.7 μm (divided into 32 mobility channels) with a combination of an electrostatic classifier (DMA) and a condensation nucleus counter (CNC), but in the size range of 1.0–10 μm with the Berner type low-pressure impactor (BLPI). The measurements were carried out at a 300 MW power plant firing Polish bituminous coal during several operating conditions for coal combustion and ESP, data being acquired by both instruments and ranges. Gas composition (NOx, SO2, CO2, CO, and O2) was monitored by gas analyzers located downstream from the ESP. The ESPs operating voltage and currents were recorded. Electrical mobility distributions were measured with prime apparatus, the DMPS system. These data were reduced to the desired number size distributions with the commercial TSI-algorithm. D50-method was applied to impactor data. Fractional penetration curves were calcul...

Submicron particle agglomeration by an electrostatic agglomerator

Abstract The new-type electrostatic precipitator (ESP) was proposed to elevate the collection efficiency for submicron-sized particles in exhausted gas from a fine-grained coal-burning boiler. This ESP is combined with an electrostatic agglomeration apparatus (EAA). This paper firstly describes the basic concept and structure of this new-type ESP. Secondly, this paper describes the theoretical and measured agglomeration operation. Finally, this paper describes the theoretical collection efficiency of the new-type model ESP. A measured weight percentage of submicron-sized particles under 1 μm decreased 20% and a mean diameter of aerosol particles increased to four times of that at an inlet when an EAA was used. The new-type ESP is expected to increase the collection efficiency from 95 to 98% due to a calculation of the collection efficiency using the measured agglomeration particle-size distribution in the range of 0.06–12 μm.

Bipolar charged aerosol agglomeration with alternating electric field in laminar gas flow

Abstract This paper presents the results of an experimental study for a method of increasing the efficiency of electrostatic precipitators for the collection of fly ash particles of submicron size. An alternating electric field was used to induce agglomeration of bipolarly charged particles (bipolar AC-agglomeration). A bench-scale AC-agglomeration test apparatus with bipolar corona charger was constructed. Test aerosol was generated from vegetable oil. The total mass loading was 0.2 gm−3 (5 × 106 particles cm−3), mass median diameter was 0.5 μm. Count median diameter was 0.2 μm, and geometrical standard deviation was 1.8. Residence time in the agglomerator was 4.8 s and the agglomerator field was 5.0 kV cm−1 (rms). Systematic experiments were conducted to investigate the agglomeration efficiency of the system. The percentage decrease in number concentration of 0.1–1.0 μm sized particles was found to be between 17 and 19%.

Electrical agglomeration of aerosol particles in an alternating electric field

A laboratory scale test system has been used to study the electrical agglomeration of charged aerosol particles to increase the collection efficiency of electrostatic precipitators. The system consists of test aerosol generator, aerosol charger, agglomerator chambers, and aerosol measurement equipment. Air atomizing nozzles and the TSI six-jet atomizer have been used as the test particle generators. The test particles have been charged by a corona discharge. Two types of agglomerator chambers have been investigated. In one agglomerator the gas flows between two parallel plates, across which the alternating high voltage is applied. The other agglomerator is a quadrupole structure with cylindrical electrodes positioned between the grounded plates. Particle concentration and size distribution measurements have been carried out downstream of the agglomerator with agglomerator voltage on and off. Particle concentrations and size distributions have been measured with differential mobility analyzer (DMA) and a Berner Low pressure impactor. Agglomeration caused about a 4%-8% decrease in the fine particle concentration when the total mass concentration was between 1 and 2 g/m[sup 3]. There was no difference between the results measured with the parallel plate and the quadrupole agglomerator. 19 refs., 7 figs., 1 tab.

Optimization of filtration efficiency and ozone production of the electrostatic precipitator

An electrostatic precipitator is an air cleaner in which particles are first charged by an electric current coming from corona wires in high voltage. Then the particles are collected by the electric field between collecting plates. The principle of the operation of an electrostatic precipitator is shown in Fig. 1. An important property of the electrostatic precipitator is the filtration efficiency. For high efficiency the charging current and collecting voltage must be sufficiently high. The higher the current the more ozone is produced. The high collection voltage may also cause ozoneproducing discharges between collection plates. The aim of this study was to investigate the filtration efficiency and ozone-production dependence on charging current and collecting voltage. This knowledge can be used when electrostatic precipitators for dwellings and public rooms are designed.

On the determination of electrostatic precipitator efficiency by differential mobility analyzer

Abstract In order to determine penetration curve of the electrostatic precipitator (ESP) as a function of aerosol particle diameter in the range of 10–1000 nm measurement series were carried out in real scale power plant conditions. Differential mobility particle sizing (DMPS) system was used to measure the particle mobility distributions before and after ESP. MICRON -algorithm (constrained regularization) was used to invert mobility distribution to the corresponding number distributions. Penetration curve was calculated from the measured number distributions.

Kinematic Coagulation of Charged Droplets in an Alternating Electric Field

An analytic-numerical model has been developed to study kinematic coagulation caused by the vibrational motion of charged particles in an alternating electric field. The primary aim of this study was to find out the reduction in the number concentration of fine particles of diameter 0.1 μm-1.0 μm caused by collisions with larger, supermicron particles. Three cases are considered: (1) unipolar charging, (2) fine particles are neutral, and (3) fine particles and large particles have opposite polarity. We find out that in cases 1 and 2 the rate of kinematic coagulation in negligible and in case 3 significant. The results are demonstrated with two sample calculations with total mass loadings of 2 and 20 g/m3. In the former, where the mass median diameter is 3.0 μm, we discover a 20%-50% reduction in number concentration of particles in the range 0.5–1.0 μm and less significant reduction in smaller particles. The latter (MMD = 6.0 μm) represents power plant conditions. In this case the reduction varies from 10...

Aerosol formation in real scale pulverized coal combustion

Abstract Aerosol formation in pulverized coal combustion have been studied experimentally at the real scale power plant. Combustion aerosol mass and number size distributions have been determined, when burning bituminous coal from Poland. Mass size distributions have been measured by low pressure impactor and number distributions by differential electrical mobility (DMA) method.

Bipolar-charged submicron particle agglomeration

Abstract We have analyzed the submicron-sized particle agglomeration theoretically by solving equations which describe the variation of particle size and charge distribution. Both the uncharged particle agglomeration and the bipolar-charge were calculated. The calculated results show that the bipolar charging is very effective for the particle agglomeration. In particular, the asymmetrical charging, in which the larger particles are charged in one polarity and the smaller ones in the opposite polarity, is very useful for the submicron-sized particle agglomeration.

Coagulation in an electrical agglomerator

Abstract The collection efficiency of all flue gas cleaning methods is considerably decreased for particles with a diameter between 0.05-0.5μm (Ylatalo et. al., 1992). The aim of this study is to investigate the reduction in the concentration of these fine particles by electrical agglomeration before they are collected.