Collection Efficiency Of Electrostatic Precipitator Research Articles

Prediction and Comparative Analysis of the Influence of Magnetic Field Effect on PM2.5 Trapping Efficiency in Electrostatic Precipitator (ESP) under Different Temperatures

Charged particles have high momentum under high-temperature conditions, which helps to promote their movement towards a dust collector in a magnetic field environment, making it possible to improve the efficiency of the high-temperature wire-plate electrostatic precipitator (ESP) in this environment. A multi-field coupling model was established to numerically simulate PM2.5 dust-removal efficiency in an ESP under different working conditions. Combining the particle swarm optimization (PSO) algorithm with the support vector machine (SVM) model, the PSO-SVM prediction model is presented. Simulated data were used as training data, and PSO-SVM and back-propagation (BP) neural network models were utilized to predict collection efficiency under different working conditions, respectively. The results show that introducing a magnetic field can effectively improve the PM2.5 collection efficiency of wire-plate ESP, and the effect of a magnetic field on the dust-removal efficiency is more obvious at higher temperatures and higher flue gas velocities. When changing the working conditions, the predicted results of the magnetic field effect conform to simulated ones, and the PSO-SVM predicted values have a smaller relative error than those of the BP model, which can better adapt to different working conditions. All of the above conclusions can be utilized as a simple and adequately efficient example of the ESP model for follow-up research.

Optimization of Sawtooth Electrode for Improving Collection Efficiency of Electrostatic Precipitator

This research used an electrostatic precipitator (ESP) with multiple sawtooth discharge electrode plates and one hollow cylindrical collecting electrode. The discharge electrode was a circular plate with sawtooth spikes. The collection efficiency was analyzed via simulations using three geometric parameters: the outermost diameter of the discharge electrode, the distance between the electrode plates, and the number of spikes. Among the cases considered for the discharge electrode geometry optimization using the Taguchi method, the parameter combination with the highest collection efficiency was selected. The simulation result was verified by building electrostatic precipitator geometry before and after its optimization and subsequently measuring its collection efficiencies. The collection efficiency of an ESP with the discharge electrode of the optimal geometry was higher by 15% than that of its reference geometry. It is expected that the collection efficiency of other types of ESP can be maximized using a similar discharge electrode geometry optimization.

Numerical Simulated and Mechanism Research on Fine Particle of Pigsty Removal in the Coupling Effection of Acoustic Wave and Electric Field

For improving the collection efficiency of electrostatic precipitator (EP) in the pigsty, MATLAB & Finite element method (FEM) is applied to calculate RNG k-ε equations, corona equation and acoustic radiation equations to analyze sound field, electric field and particle trajectory in the wire-plate EP. The results show that fine particle agglomeration can be induced, so as to promote the enlargement of fine particles and improve the capture efficiency of fine particles at acoustic node area. Moreover, the particle distribution can be controlled according to the above V-η curve in the pigsty. In addition, η initially increases, and then decreases in the range of f from 1000 Hz to 2000 Hz. Therefore, the linear variation law of V– η & SPL – η & f – η provide scientific control method for the construction of green and efficient removal technology of particulate pollutants in the piggery.

Performances of a new type high-temperature tubular electrostatic precipitator with rare-earth tungsten cathode

Dust removal experiments of rare earth tungsten cathode tubular electrostatic precipitators (ESPs) were carried out at high temperatures from 1073 to 1373 K. The impact of various factors on dust collection efficiency was investigated. The results show that at temperature of 1173 K and working voltage of 4000 V, the dust collection efficiency of La-W cathode single tube ESP can reach 98.22% on coal-fired power plant flying ash. Compared with the single tube ESP, the dust collection efficiency of a double tube ESP is improved. Although the tubular rare earth tungsten cathode high-temperature ESPs have higher collection efficiency for particles greater than 5 μm, they can’t collect fine particles smaller than 5 μm efficiently due to the limitation of their maximum working voltage. With rise of working voltage or temperature, the collection efficiency mainly shows evident increase tendency, while a little decrease with increasing temperature at higher temperature and lower voltage. Larger anode tube presents lower collection efficiency. Higher dust concentration leads to lower dust collection efficiency due to particle accumulation and deposition on the cathode surface. At low voltage (<3500 V), the dust collection efficiency can be significantly enhanced by extending the rare earth tungsten cathode.

An experimentally validated computational model to predict the performance of a single-channel laboratory-scale electrostatic precipitator equipped with spiked and wire discharge electrodes

The validation of a computational model for predicting the performance of a laboratory-scale, single channel, multi-electrode electrostatic precipitator (ESP) was undertaken. This consisted of comparison of experimental and modelling results obtained for different geometrical and operating parameters, such as the plate spacing, the inter-electrode spacing, the number of electrodes, the electrode design, the applied voltage, particle size and gas flow rate. Wire discharge electrodes and a spiked shaped discharge electrode were used to study the efficiency of fly ash removal from a gas stream. The validation included the comparison of the applied voltage versus discharge current (V-I) relationships, and a study of the particle collection efficiencies obtained from experimental measurements and modelling results. The presence of shielding, which was predicted to occur with specific plate-to-plate and wire-to-wire spacings for the multi wire-electrode cases that were studied, was also validated using the measurement data. Experimental results obtained with a spike electrode also correlated well with the model predictions in terms of ESP collection efficiency under varying geometric and operating parameters. Such a fundamentally based, validated computational model of ESP processes would be useful in developing process models that have an improved accuracy compared to current semi-empirical models. This, in turn, will be invaluable in maximizing particulate matter removal from industrial flue gas streams in a cost-efficient manner.

Optimization of pipe-and-spike discharge electrode shape for improving electrostatic precipitator collection efficiency

Numerical analysis was conducted to investigate the effect of wire length, spacing between wires, and wire bending angle, which are geometric parameters of a pipe-and-spike discharge electrode, on collection efficiency. Discharge electrode shape was optimized using the Near Orthogonal Array method. When the distance between collecting plates and the number of discharge electrode wires were fixed, a longer wire length and greater distance between the wires increased the collection efficiency, which was the highest when the bending angle of the wire was 160°. Numerical results were validated through experiments. Collection efficiency of the electrostatic precipitator was increased by about 15% by the optimized discharge electrode, and power consumption and ozone generation showed little difference after optimization. Based on the results of this study, the optimization of the shape of various discharge electrodes is expected to effectively improve the collection efficiency of various types of electrostatic precipitators.

High-efficient removal of airborne oil mist in a wire-plate electrostatic precipitator

Electrostatic precipitators (ESPs) are widely used by machining industries to remove oil mist due to the high efficiency, low pressure drop and low energy consumption. In this paper, the effects of oil mist concentration, relative humidity and oil film thickness on the collection efficiency of ESPs were studied. The experimental results showed that discharge current and collection efficiency both decreased with increasing oil mist concentration, and the collection efficiency of fine oil droplets decreased more obviously than that of large-size oil droplets. When the oil mist concentration increased from 100 mg/m3 to 300 mg/m3, collection efficiency of oil droplets with a size of 0.33 μm dropped from 87.13% to 73.53%, while the efficiency for the droplet size of 1.25 μm only dropped from 90.7% to 84.1%. Increasing the relative humidity caused a considerable decline in discharge current due to the decrease in ion mobility, but an appropriate increase in humidity was conducive to the improvement of collection efficiency. The stable status of oil film thickness on electrode plate was obtained (about 10 μm in the current study), and the stable current density decreased almost 11% due to the oil film. Compared with the oil droplets deposited on the electrode wires, the oil droplets deposited on the plate caused more decrease of collection efficiency of ESPs. The decrease in collection efficiency effected by the electrode plate with oil film was twice that of the electrode wires with oil contamination.

Design and optimization of waste heat recovery system for supercritical carbon dioxide coal-fired power plant to enhance the dust collection efficiency

The supercritical carbon dioxide (SCO2) power cycle is a potential power cycle for coal-fired power plants. In the SCO2 power systems provided in previous studies, the boiler exhaust temperature is about 120 °C. To enhance the power plant efficiency and the dust collection efficiency of electrostatic precipitator, SCO2 power systems should be advanced to cool the boiler exhaust fluegas to nearly 95 °C. Therefore, systems of waste heat recovery from low-temperature fluegas are proposed and optimized in this study. Thermodynamic and optimization models are developed. The double reheat recompression SCO2 cycle is optimized as benchmark system. The benchmark system is improved to decrease the exergy loss and boiler exhaust, decrease the irreversibility of air preheater, and recover waste heat of the SCO2 cycle to preheat air to the air preheater. When the main compressor intercooling or bypass fluegas ahead the air preheater is adopted, the temperature of boiler exhaust fluegas can be decreased to around 95 °C which can ensure a high dust collection efficiency of electrostatic precipitator. The power plant efficiency is also increased as a result. However, if only low-temperature economizer is integrated, then the power plant efficiency is enhanced slightly by 0.09%-pts. If the low temperature economizer is integrated with other system improvements, the power plant efficiency can be enhanced by 0.89%-pts. Exergy analysis is also performed to reveal the mechanisms of efficiency enhancement.

A Numerical Investigation of the Effect of Dust Layer on Particle Migration in an Electrostatic Precipitator

ABSTRACT Electrostatic precipitation processes have been widely applied to remove particulate matter from flue gases in coal-fired power stations. A high negative voltage is usually applied to a discharge electrode so that the gases are ionized in such processes. When the suspended particles in flue gases enter the ionized space, they are electrically charged and deposited on collection plates to form the layer of particle packing. However, the dust layer generally exists during the precipitation of charged particles on the collection plate. The negative effect of precipitated dust layer on the collection plate causes the collection efficiency of electrostatic precipitator (ESP) to deteriorate seriously due to some critical factors, such as dust resistivity and thickness of accumulated dust. In this study, a simulation method by computational fluid dynamics method was applied to investigate the particle collection performance of the ESP system with and without a dust layer. Also, the detailed electric parameters and particle capture performance in the 2D wire-plate electrode configuration were simulated. The results show that the voltage-current characteristics and detailed distribution of electric field and ion charge density are completely different under various dust resistivity conditions. The effect of the dust layer is significant, which causes collection efficiency to decrease sharply with the increasing thickness (1–5 mm) of the dust layer. Furthermore, results indicate that when particles with higher resistivity enter the ESP, their migration velocity decreases sharply. In the case of 80 kV, when the dust resistivity is 1012 Ω·cm, the decline rate of particle migration velocity reaches 57.7%. Meanwhile, useful suggestions were provided to reduce the effects of dust layers by regulating particle properties and designing dust removal systems.

Influence of ESP collector configuration on reduction of particulate emissions from biomass combustion facility

Development of compact electrostatic precipitators (ESPs) for reduction of particulate emissions from small scale biomass combustion is an actual task. Particle mass collection efficiency of an ESP depends from combustion conditions, geometry of precipitator ionizer, collector stage configuration and ESP operation parameters. The investigation of the influence of collector stage configuration on particle mass collection efficiency of a pilot space charge ESP was in the focus of the study. It was shown that the use of tube collector with integrated grounded plates enhanced particle mass collection efficiency. The loading of plates with aerosol provoked particle re-entrainment and decreased long-term ESP mass collection efficiency. The use of grounded brush electrodes ensured effective reduction of particle emissions but resulted in increase of pressure drop in the precipitator. The optimization of cleaning intervals of the ionizer and collector stages increased particle mass collection efficiency. It was shown, that the integration of automatic systems for ionizer and collector cleaning into the space charge ESP enhanced precipitator long-term operation stability and ensured effective reduction of particulate emissions form small scale biomass combustion.

Effect of Particle Size on Collection Efficiency of ESP and RABH: A Case Study

Electro Static Precipitator (ESP) is a conventional dust collecting equipment used in various process industries. Nowadays bag houses and Reverse Air Bag Houses (RABH) are also widely used in place of ESP. RABH is comparatively new technology which is used in cement plants and also other industrial facilities for dust collection. The dust collection efficiency of the ESP and RABH depend on many factors and particle size is one of those factors. Many researchers have done research on the collection efficiency of ESP with respect to the particle size distribution in dust-laden inlet gas, however, there is merely any study done on RABH collection efficiency with respect to the dust particle size distribution. A case study has been conducted in this research to find out the relationship between particle size distribution and collection efficiency of RABH in a cement plant. In addition to this, the collection efficiency of ESP is also studied with respect to the dust particle size distribution in inlet gas. The study has been conducted by taking the samples at inlet and outlet of ESP and RABH for calculation of efficiency and different particle size percentage at inlet side. It is found that the collection efficiency of both ESP and RABH is dependent on the size of the incoming dust load. In ESP the collection efficiency is higher when the particle size is smaller than 0.2 μm (PM0.2) and larger than 1 μm i.e., PM2.5 and PM10. The collection efficiency is lower when the particle size lies between 0.2 and 1 μm. In RABH it is observed that the collection efficiency increases with increase in the size of dust particles. Also a comparative study has been conducted to find out the better system between ESP and RABH by the help of sampling analysis (t test), field survey and performance parameter study. It is found that RABH is better than ESP in terms of collection efficiency and other performance parameters.

The Influence of Electrohydrodynamic Secondary Flow on the Collection Efficiency and Deposition Pattern in ESP

Electrostatic precipitator (ESP) is widely used for dust removal from flue gas in industry. In the electrostatic precipitation, the electrohydrodynamic secondary flow (EHD) produced by corona ionization has an important influence on the characteristics of particle transport and the collection efficiency of ESP. In this work, a comprehensive ESP model with interaction of multiple physical fields is established to study the EHD effect in ESP. The numerical results show that the EHD generally can increase the streamwise velocity of airflow near the collection plate, which makes the removal performance of ESP worsen. Meanwhile, the EHD has a significant effect on the particle deposition pattern, especially at lower flue gas velocity. When the needle tip of discharge electrode points to the collection plate, the EHD can promote the circulation of airflow near the corona wire, increase the probability of particle charging, and then improve the collection efficiency of ESP.

Study on Atomization Characteristics of Nozzles in Wet Electrostatic Precipitator

Wet electrostatic precipitator (ESP) has been paid more and more attention because of its good collection effect on fine particles in coal-fired power plants. Spraying system is an important part of the wet ESP and its atomization characteristics has an important influence on the collection efficiency. The atomization performance of solid and hollow nozzles was tested under varying pressure. The dust collection efficiency of wet ESP affected by atomization parameters and corona discharge characteristics were studied. Dust removal experiments were carried out by using fly ash from coal-fired power plants. Results show that the best working water pressure of ESP is 0.6 MPa and the atomization effect is best at the same time. Under the same conditions, the dust collection efficiency increased with the decrease of droplets’ diameter and the increase of spray water flow rate. When the droplets’ size is 70 μm, the dust collection efficiency can reach 99.57%, which can meet the high efficiency of fine particles removal in coal-fired power plants.

A numerical model for predicting particle collection efficiency of electrostatic precipitators

The performance of electrostatic precipitators has been predicted by the Deutsch equation and its modifications over a long period, and ESP index is a good tool among them which considers the importance of electrical discharge. The present work shows the theoretical development of ESP index and the relevant model. The collection process considering migration induced by both electrostatic attraction and deposition is simulated. Subsequently, the model is applied to calculate grade collection efficiency for particles larger than 0.02 μm in electrostatic precipitators. The physical meaning of two coefficients, α (relative to particle charging and migration) and β (relative to particle deposition) in the model is clarified. By integrating and averaging the α and β values, the overall collection efficiency is obtained. The present predictions agree well with experimental data. The model is also able to predict variations of particle collection at different gas temperature. The particle mass emissions at the ESP outlets decrease linearly with the ESP index or its square root. It is expected that the present model can facilitate the design and sizing of the ESPs.

A Novel Method of Collecting and Chemically Characterizing Milligram Quantities of Indoor Airborne Particulate Matter

ABSTRACT Because people spend the majority of the day indoors, it is important to evaluate indoor air, especially airborne particulate matter (PM), for its potential health effects. However, collecting milligram-sized samples of indoor PM, which are necessary for detailed chemical and biological assays, remains challenging because of the noise, power requirements, and size of traditional PM samplers. Therefore, we developed a novel method of collection using an electrostatic precipitator (ESP). Laboratory experiments were conducted to characterize the ESP collection efficiency (41–65%) and PM recovery (50–95%) for three aerosol types. After characterization, the ESPs were deployed in 21 homes in eastern Iowa for 30 days, during which they collected 6–87 mg of indoor PM. The samples were acid digested and subsequently analyzed by inductively coupled plasma mass spectrometry for their magnesium, aluminum, vanadium, manganese, iron, nickel, copper, zinc, arsenic, and lead content. Crustal metals (magnesium, iron, and aluminum), ranging from 3,000 to 25,000 ng mg–1 in concentration, contributed the largest mass fractions of the PM. The relative abundances of the metals were similar between homes, although the PM mass fractions were highly variable. This ESP sampling method can be applied in future studies to collect milligram-sized quantities of indoor PM, enabling a detailed analysis of its composition and potential health effects.

Velocity field of EHD flow during back corona discharge in electrostatic precipitator

Particle Image Velocimetry studies of velocity field of the EHD flow during the back corona discharge at atmospheric pressure in an electrode system comprising a needle discharge electrode at negative potential and a grounded plate collection electrode covered with fly ash layer are presented in this paper. It was found that the magnitude of velocity vector of the EHD flow starting from the crater formed in fly ash layer after the onset of back corona discharge is of the same order of magnitude as for the flow generated by the corona discharge from the needle electrode. The measurements have shown that both these flows do not mix, but deflect each other off the axis of the needle electrode. The conclusion from this research is that the EHD deflection of the trajectories of particles flowing towards the collection electrode by the particles erupted from the crater at the collection electrode probably prevents those particles from the precipitation on the collection electrode that can result in a decreased collection efficiency of electrostatic precipitator during back corona discharge. This new mechanism has been called the “dynamic” process of the collection efficiency reduction.

Effects of coal blending in electrostatic precipitation efficiency—Inner Mongolia, China

Based on this study, the Al2O3 content of Jungar coal ash is over 45%, and the resistivity of high-Al2O3 ash in Jungar reaches up to 1012Ω​·cm. These results seriously influenced the electric characteristics of fly ash, and the collection efficiency of electrostatic precipitators (ESPs) evidently decreased. To facilitate the effective collection of fine particle in the flue gas generated before and after coal blending via ESP, the fly ash obtained from a power plant electrostatic precipitation was analyzed in terms of resistivity, size distribution, and cohesive force through a portable dust electrical resistivity test instrument, Bahco centrifuge, and a cohesive force test apparatus invented by the researchers. The mixed ratio of else coal is higher than 50%, the resistivity of the fly ash in the flue gas was lowered to approximately two orders of magnitude, and the size distribution showed an evident decrease in the PM2.5 and PM10 content in fly ash. In addition, the adhesive force and efficiency increase from 95.9 to 99.5% in the electrostatic precipitation. Therefore, the combustion of blending coal is an effective approach to improve the efficiency of ESP used to collect high-Al2O3 fly ash.

Experimental and analytical study on the performance of novel design of efficient two‐stage electrostatic precipitator

This study presents a novel design of high-efficiency two-stage electrostatic precipitator (ESP). For its design, different electrode configurations were tested and the corresponding onset and breakdown voltages were measured and compared. Based on findings, an optimal arrangement was then defined and a novel design of a two-stage ESP prototype, using needle electrodes instead of long wires utilised in conventional ESPs, is realised. For comparison, a single-stage ESP was also built. The influence of various parameters on the performances of both two-stage and single-stage ESPs was evaluated numerically using 2D modelling and compared with the experimental ones for the same dimensions of laboratory-scale ESP. The numerical simulation was implemented using COMSOL Multiphysics package that uses finite element method (FEM) solver. The main investigated parameters are the electric potential, electric field distribution and collection efficiency under the loading conditions as a function of air flow velocity, magnitude and polarity of voltage, ESP geometry design (size, shape and number of discharge electrodes). It is shown that the collection efficiency of this novel ESP increases when decreasing air flow velocity; and its effectiveness is higher when using negative ionisation polarity. Also, the collection efficiency of this ESP could greatly improve the existing ESPs under the same applied physical conditions.

Investigating the impact of an Al-Si additive on the resistivity of biomass ashes

Ash resistivity is an important factor in the collection efficiency of electrostatic precipitators (ESPs). There is good experience in the industry regarding resistivity of coal fly ash and well-established models for its prediction based on coal ash composition. The same is not true for biomass ash and this paper reports much-needed data for three different biomass types. Coal pulverised fuel ash (PFA), can be used as an aluminosilicate additive to mitigate biomass ash deposition issues. The effects of PFA additive on the resistivity of biomass ashes is also reported here. Biomass ash resistivity is an order of magnitude lower than that of typical coal ashes, and thus re-entrainment of particles in ESPs may become an operational issue, exacerbated by the presence of moisture and sulphur. PFA additive can increase the resistivity, but also leads to higher ash loading. Regression analysis indicates that potassium in biomass ash impacts significantly upon resistivity, contrary to previous studies. Various existing resistivity models were tested for predicting biomass ash resistivity; they produced significant overestimates when compared to experimental results due to omission of potassium as a component of the ash. Modifications to existing models or new models are required to predict resistivity of biomass ashes, and the data reported here will be important for developing such a model.

Electrostatic Precipitation of Submicron Particles with an Enhanced Unipolar Pre-Charger

A two-stage electrostatic precipitator (ESP) has been developed using an enhanced unipolar pre-charger with dielectric coated ground electrodes. The electrical and particle collection performance was evaluated for particles in the submicron range. By varying the voltage applied to the pre-charger, the particle charging characteristics was compared with that calculated by the theoretical model. The experimental results show that with the adoption of the pre-charger, the charging of the particles at submicron range was enhanced. Further results indicate that the collection efficiency can be improved by about 12.1%–15.9%, compared with the results obtained without the pre-charger. Higher particle collection efficiency can be achieved by increasing the voltage applied to the pre-charger. The unipolar pre-charger studied in this paper proves to be a simple and useful device to improve the submicron particle collection efficiency of conventional ESPs.