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Keping Yan

Electrostatic Precipitation

11th International Conference on Electrostatic Precipitation, Hangzhou, 2008

Keping Yan

Electrostatic Precipitation 11th International Conference on Electrostatic Precipitation, Hangzhou, 2008 With 910 figures

EDITORS: Prof. Dr. Keping Yan Dept. of Environmental Science Zhejiang University Hangzhou, 310028 China E-mail: [email protected]

___________________________________________________________________ ISBN 978-7-308-06291-6 Zhejiang University Press, Hangzhou ISBN 978-3-540-89250-2 Springer Berlin Heidelberg New York e-ISBN 978-3-540-89251-9 Springer Berlin Heidelberg New York ___________________________________________________________________ Library of Congress Control Number: 2008938257 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable to prosecution under the German Copyright Law. © 2009 Zhejiang University Press, Hangzhou and Springer-Verlag GmbH Berlin Heidelberg Co-published by Zhejiang University Press, Hangzhou and Springer-Verlag GmbH Berlin Heidelberg Springer is a part of Springer Science+Business Media springer.com The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: Frido Steinen-Broo, EStudio Calamar, Spain Printed on acid-free paper

The 11th International Conference on Electrostatic Precipitation was organized by

The International Society for Electrostatic Precipitation (ISESP) and Local Chinese Organizing Committee

ISESP Board Members (http://www.isesp.org/) Robert Crynack - President, USA Tetsuji Oda - Vice-president, Japan Wallis Harrison - Secretary, USA Mark Berry - Treasurer, USA Ralph Altman - USA Veronique Arrondale - France Istvan Berta - Hungary Hidekatsu Fujishima - Japan Michael J. Frank - Germany P. Gurnani - India Carsten Lund - Denmark Jae-Duk Moon - Korea Kjell Porle - Sweden Gernot Mayer-Schwinning - Germany Liqian Wang - China Keping Yan - China

Conference Chairman: Jiming Hao Conference Vice-Chairmen: Robert Crynack

Youwen Lin Liqian Wang Keping Yan

Conference Secretary: Weiping Liu Keping Yan

Preface

We are pleased to welcome you to Hangzhou for ICESP XI. The concept of providing a forum for the exchange of information on research and application of electrostatic precipitation originated with Dr. Harry J. White. Then, the first conference was held in Monterey, California, USA, in October 1981. And the succeeding meetings were held in Kyoto, Abano Terme, Beijing, Washington DC, Budapest, Kyongju, Birmingham, South Africa, and Australia.

The focus of this meeting is on fundamental and applied electrostatic precipitation, bag filter, FGD, SCR and non-thermal plasmas for multi-pollutants emission control, such as PM2.5, SOx, NOx, Hg, VOC, and HC.

We dedicate the open session to Prof. Hongdi Zhang for his outstanding contributions to the organization of Chinese Society of Electrostatic Precipitation, the development of ESP and non-thermal plasma techniques. He was the first Secretary of Chinese Society of Electrostatic Precipitation, and one of the advisory committee members of ICESP XI. Prof. Zhang was born in Jan 1933 in Liaoning, and received his B.S. degree from Northeastern University, China in 1956. Then, he joined the Beijing Municipal Institute of Labour Protection to work on environmental protection. He is one of Chinese pioneers to dedicate their life to ESP, even during the period of the so-called Chinese Cultural Revolution. Back to the early of 1970’s, Prof. Zhang established an ESP lab with the institute to study ESP for dust, aerosol, and gas cleaning. Around 1988, together with Prof. Ruinian Li, he promoted the first non-thermal plasma project in China to study DeNOx and DeSO2. For over his 50 years professional life, he contributed himself not only to ESP industries but also to education and students. Unfortunately, Prof. Zhang passed away in July 2008, leaving many unfinished works. We would like to thank his family, his students, friends and Chinese ESP committee for encouraging us to dedicate the open session in memory of Prof. Hongdi Zhang.

We would also like to acknowledge financial supports from local Chinese industries, National Natural Science Foundation. All students in my laboratory provided invaluable assistance in preparing this conference. They are W. Chen, Y. Huang, X. Li, X. Tang, X. Zhang, Z. Zhang, J. Zhu, and H. Yan. We also like to thank Mr. Sun Hairong from the press company for his help to revise this proceeding.

We thank all the authors for their high quality contributions, session chairs, ISESP board, local organizing and advisory committee members for their comments and assistances.

Prof. Dr. Keping Yan 2008-10-08

CONTENTS 1

CONTENTS World-Wide Review Development of Chinese Electrostatic Precipitator Technology

Y. Lin, W. Liu 3 Multi-pollutants Simultaneous Removals from Flue Gas

X. Gao, Z. Wu, X. Shen, Z. Luo, M. Ni, K. Cen 12 Some Technical Idea Evolutions Concerned with Electrostatic Precipitators in China

L. Wang, B. Fu 19 Enhancement of Collection Efficiencies of Electrostatic Precipitators: Indian Experiments

Avinash Chandra 27 Fundamentals and Mechanical Design Modeling Mercury Capture within ESPs: Continuing Development and Validation

Herek L. Clack 37 Reduction of Rapping Losses to Improve ESP Performance

Stephen L. Francis, Andreas Bäck, Per Johansson 45 Advanced Risk Analysis for the Application of ESP-s to Clean Flammable Gas-pollutant Mixtures

István Kiss, Tamás Iváncsy, Bálint Németh, István Berta 50 ESP for Small Scale Wood Combustion

A. Laitinen, K. Karjalainen, A. Virtanen, J. Keskinen, M. Aho, J. Maunuksela, I. Talka 54 Dust flow Separator Type Electrostatic Precipitator for a Particulate Matter Emission Control from Natural Gas Combustion

L. Guan, G. Harvel, S. Park, J.S. Chang 57 Electrostatic Precipitator: The Next Generation

Roger Anthony Gale 62 Current Density and Efficiency of a Novel lab ESP for Fine Particles Collection

J. Zhu, Y. Shi, X. Zhang, H. Yan, K. Yan 65 Five Stages Electrostatic Precipitator Principles and Application

G. Xu, L. Xu 70 Application of STAAD in ESP structure design

H. Xie, R. Peng, X. Gao 73 Electric Resistance of Boiler Flue Gases and Collection Efficiency of ESP

X. Zhao 75 Non-static Collection Process of the Electrostatic Precipitator

W. Hao, H. Xiong 79 Study of Using Mixed Discharge Electrodes and Mixed Spacing of Pole to Pole for Electrostatic Precipitator

Q. Fang, B. Zhang 84 Experimental Investigation on the Collection of Fine Dust with High Resistivity by a Bipolar Discharging ESP

X. Xiang, Y. Wang, W. Chen 87 Designing ESP Systemically to Reduce Dust Emission

X. Lu, P. Ming, T. Wang, X. Gao, Z. Li 91 Research on Vibration Period Optimization of Electrostatic Precipitator

M. Hu, Y. Liu, Q. Yin, Z. Liu, X. Gao 94 Study on the Dust Removal Efficiency Formula of EP with Efficiency Enhancing and Energy-saving

Q. Fu, Z. Lu, M. Hu, X. Gao, Y. Liu 98 Research and Application of the Extensive Resistivity and Efficient Electrostatic Precipitator

S. Huang, W. Liu, H. Tao 102

11th International Conference on Electrostatic Precipitation 2

Application and Research on Technology of Longking Brand BEL Model ESP Z. Liao 106

Electrode Shape and collector plate Spacing Effects on ESP Performance Niels Finderup Nielsen, Christian Andersson 111

Resistance and Airflow Distribution of Rotary Plate G. Xu, S. Yuan 119

Onset Voltage of Corona in Electrostatic Filters as Influenced by Gas Flow M. Abdel-Salam, A. Hashem 121

An Initial Exploration for Coulomb ESP L. Jin 125

Aerodynamic Effects and ESP Models Effect of the EHD Flow on Particle Surface Charging and the Collection Efficiency of Submicron and Ultrafine dust Particles in

Wire-plate Type Electrostatic Precipitators D. Brocilo, A. Berezin, J.S. Chang 129

Electrohydrodynamic Turbulent Flow in a wide wIre-plate Electrostatic Precipitator Measured by 3D PIV Method J. Podlinski, A. Niewulis, J. Mizeraczyk 134

Applying Numerical Simulation on Air Pollution Control Equipment Kasper Gadegaard Skriver, Niels Finderup Nielsen 140

CFD Simulation of Electrostatic Precipitators and Fabric Filters State of the Art and Applications M. Feldkamp, M. Dickamp, C. Moser 141

Numerical Modeling of the Electro-hydrodynamics in a Hybrid Particulate Collector Z. Long, Q. Yao, Q. Song, S. Li 151

CFD Numerical Simulation of ESP Airflow Distribution and Application of Flue Gas Distribution B. Xie 157

Study and Application of Numerical Calculation Method for Gas Flow Distribution of Large Scale Electrostatic Precipitator X. Dang, H. Hu, G. Ma, D. Yan 164

Experimental Study on Optimization of Electric Field Performance for Electrostatic Precipitator by Using Finite Element Method X. Dang, D. Li, G. Ma, Y. Ren, Y. Shi 169

Analytical study on ZT Collecting Electrode Y. Dai, K. Huang 175

Model EE I Technology in 1#125 MW Unit of Electrostatic Precipitator Application for GUODIAN Kaili Power Plant B. Xie 179

Model EE II Technology in 2#600 MW Unit of Electrostatic Precipitator Application for GUODIAN Kaili Power Plant B. Xie 183

Numerical Simulation of Influence of Baffler in Electric Field Entrance to Form Skewed Gas Flow M. Hu, X. Sun, C. Ma, Y. Liu, L. Wang 187

A numerical Simulation for Predicting Influence of Flow Pattern in Electrostatic Precipitator on Exit Re-entrainment Loss Z. Du, Q. Xie 194

Fine-Particles and Their Agglomeration Research Progress of the Control Technology of the PM10 from Combustion Sources

Q. Yao, S. Li, Q. Song, B. Huang, H. Xu, G. Liu 201 Enhanced Fine Particle and Mercury Emission Control Using the Indigo Agglomerator

Rodney Truce, Luke Wilkinson 206 Emission Reductions at a Chinese Power Station

John Wilkins, Luke Wilkinson, D. Li 215 On-line Measurement of Hazardous Fine Particles for the Future APC Technology

Christer Lofstrom, Karsten Poulsen 223 A Novel Method for Particle Sampling and Size-classified Electrical Charge Measurement at Power Plant Environment

Ville Niemelä, Erkki Lamminen, Ari Laitinen 228 Agglomeration Modelling of Sub-micron Particle During Coal Combustion Based on the Flocculation Theory

K. Zhang, J. Zhang, H. Li, Y. Zhao, L. Zhang, C. Zheng 234 Integrated Control of Submicron Particles and Toxic Trace Elements by ESPs Combined with Chemical Agglomeration

H. Li, J. Zhang, Y. Zhao, L. Zhang, C. Zheng 238

CONTENTS 3

Electrostatic Capture of PM2.5 Emitted from Coal-fired Power Plant by Pulsed Corona Discharge Combined with DC Agglomeration F. Xu, Z. Luo, B. Wei, L. Wang, X. Gao, M. Fang, K. Cen 242

An Approximate Expression for the Coagulation coeFficient of Bipolar-charged Particles in an Alternating Electric field B. Tan, L. Wang, Z. Wu 247

Improving Nano-particle Collection Efficiency and Suppressing Particle re-entrainment in an AC Electrostatic Precipitator with Hole-punched Electrode

Koji Yasumoto, Akinori Zukeran, Yasuhiro Takagi, Yoshiyasu Ehara, Toshiaki Yamamoto 251 Electrical Operation and Power Sources Precipitator Performance Improvements and Energy Savings Based on IGBT Inverter Technology

Norbert Grass, Andreas Zintl 259 Performance Enhancements Achieved with High Frequency Switch Mode Power Supplies

H. Herder 264 High Frequency Power Supply Operation on Hot-Side ESP

M. Brandon Looney, Mark Berry, H. Herder, R. Guenther, R. W. Smith, R. Altman 270 Industrial Applications of Three-phase T/R for Upgrading ESP Performance

B. Zhang, R. Wang, K. Yan 276 Industrial Applications of a New AVC for Upgrading ESP to Save Energy and Improve Efficiency

J. Ma, Y. Yang, R. Wang, K. Yan 281 Highly efficient switch-mode 100 KV, 100 KW power supply for ESP applications

Alex Pokryvailo, Costel Carp, Cliff Scapellati 284 The Crystal Ball Gazing with Electrostatic Precipitators: V-I Curves Analysis.

V. Arrondel, G. Bacchiega, N. Gautier, M. Hamlil, A. Renard 289 New Automatic Voltage Control Designs for Enhanced ESP Systems Integration, Improved Reliability, Safety and

Troubleshooting Capabilities John Comer, Royce Warnick, Mike Volker, Jason Horn 298

Another Concept of Three Phase High Frequency High Voltage Supply Caryl Thomé, Denis Dupas 304

Development and Application Features of High Power High Frequency Power Supply for ESP Y. Chen, G. Lu, J. Guo 305

The Application Strategy of Three-phase HV Power Supply for Special Working Condition Y. Xie 310

Applying the Technology of Compounded Type Power Control Rapping to Reduce the Outlet Emission Concentration D. Lin, G. Zheng, J. Qiu, J. Guo 314

Study on Efficiency Enhancing and Energy Saving of High Voltage Power Supply of EP Y. Lei, M. Hu, Y. Liu, X. Gao, L. Wang 319

Serial/Parallel Resonant Converter (SPRC) in ESP Power G. Zhang 323

The Development And Application of an Energy Saving System Based on the Optimal Control and Multi-parameter Feedback G. Zheng, X. Xie, J. Guo, J. Li, J. Lian 328

Query on the Sustainable Development of Traditional Dust Precipitation Using Optimal Electric Spark Rate F. Zhao, W. Yu, Z. Li, Y. Lu, J. Bian, S. Zhao, X. Zhang, Y. Dong 332

Comparative Study of Distribution of Collecting Plate Current Density on Electrostatic Precipitations with High Direct Current and Pulse Power Supply

J. Li, W. Cai 337 Development of Energy Saving and Efficiency Enhancing Electrostatic Precipitator Power Supply Control Equipment

Z. Lu, Q. Fu, Y. Li, J. Gao 341 Research on High Frequency Switched HV Power Supplies for ESP

R. Wang, Y. Wei 345 Design of Switch Mode Power Supply for ESP

A. Wang 348 Research and Application of Automatic Control Technology of Back Corona

J. Qiu, J. Guo, X Xie 350 The Research on Three-phase Medium-frequency DC High-voltage Power

Y. Jiang, Z. Zhang 354


Investigation of Current Density Distribution Model for Barb-plate ESP Y. Guo, X. Xiang, B. Chen 359

SLC500 Programmerable Logic Controller Hot Standby Two-node Cluster Y. Ge 363

Evaluation of HV Power Source for ESP X. Zhou, F. Tang, J. Du 366

V-I characteristic Principle of Electrostatic Precipitator J. He, G. Xu, G. Yu 370

Enhanced Fine Particle Collection by the Application of SMPS Energization Kenneth Parker, Arne Thomas Haaland, Frode Vik 374

Two ESP Power Supply Patent Technologies W. Wang 381

Flue Gas Conditioning and Back Corona Particulate and Mercury Emissions Control by Non-traditional Conditioners

Rabi K. Sinha 387 Flue Gas Conditioning

S. N. Trivedi, R. C. Phadke 389 Modeling of Back Corona in Pulse Energized “Multizone” Precipitators

Tamás Iváncsy, Jen Suda, István Kiss, István Berta 395 Some Investigations on Fly Ash Resistivity Generated in Indian Power Plants

Avinash Chandra 399 Enhancing ESP Efficiency for High Resistive Fly Ash by Reducing Flue Gas Temperature

Andreas Bäck 406 The Technical and Economical Analysis on the Application of FGC in Large Scale Coal-fired Units

Q. Liu, X. Chen, W. Chen 412 Upgrading of Existing Electrostatic Precipitator Advanced Methods of Upgrading Electrostatic Precipitators

Tuomas Timonen, Alain Bill, Tarun Kr Ray, Minna Pelkonen, Hans-Eric Christiansson 419 Challenges for Reduction in Emission in Old Electrostatic Precipitators at Lower Cost

Debasish Chakrabarti, Robert Pritchard, Martin Kirsten, Christer Mauritzson 425 Least Cost to Maximise Dust Collection in Electrostatic Precipitators

Martin Kirsten, Anders Karlsson, Christer Mauritzson, Lena Lillieblad 429 ESP Renovation in Da Wukou Power Plant, Ningxia

P. Zhang 437 Hybrid ESP & FF Precipitation Cost Effectively increasing the Filtration Area in Fabric Filters for Large Power Plants

Peter Wieslander, Stephen L. Francis 443 Long-term COHPAC Baghouse Performance at Alabama Power Company’S E. C. Gaston Units 2&3

Kenneth M. Cushing, W. Theron Grubb, Byron V. Corina, Ramsay L. Chang 449 Study of the Use of Bag Filters in Hot Gas Filtration Applications: Pilot Plant Experiences

B. Alonso-Fariñas, M. Lupión, B. Navarrete, V. J. Cortés 459 The R&D and Application of Electrostatic-fabric Organic Integrated Precipitator in China

W. Huang, H. Lin, K. Zheng 464 Research on Performance of Electrostatic-bag Precipitator with Comparative Industrial Tests

X. Dang, Y. Shi, G. Ma, D. Li 468 A Discussion on the ESP-FF Hybrid Precipitator

X. Zhao, S. Luo 472 Collection of High Concentration of Desulfurized Dust with ESP & FF

J. Ge, Y. Zhang, G. He, P. Zhang, D. Zhou 474 Application of ESP and Fabric Filter in Power Plants in China

X. Zhao, Y. Yao, Y. Du 478 Application of Electrostatic Fabric Hybrid Particulate Collector

Y. Yao, X. Zhao 482

CONTENTS 5

Application of ControlLogix in Remote Monitoring System of ESP-FF Hybrid Precipitator Y. Ge, T. Yu, L. Zhao 485

Numerical simUlation on a Hybrid Electrostatic-bag Precipitator J. Chen, X. Han 489

Wet Electrostatic Precipitation Evaluation of Corrosion-Resistant Alloys for Wet Electrostatic Precipitator

Keigo Orita, Nobuhiko Shiromaru 495 Wet ESP for the Collection of Sub-micron Particles, Mists, and Air Toxics

Michael R. Beltran 499 Industrial Applications for Coal-fired Boilers A Discussion about Strategy of Flue Gas Dust Removal for Indian Coal Fired Boiler

G. Lin 509 Assessment of Hot ESPs as Particulate Collector for Oxy-coal Combustion and CO2 Capture

Porle Kjell, Bäck Andreas, Francis Steve, Rydberg Stina 513 Recent Application and Running Cost of Moving Electrode Type Electrostatic Precipitator

Toshiaki Misaka, Yoshihiko Mochizuki 518 Retrofit of Capacity Expansion for ESPs of Boiler 2# of Aiyis power Plant in Jiaozuo

L. Yang, K. Bao, J. Li, R. Ma, X. Cheng 523 Study on Improving the Performance of Electrostatic Precipitator in the Large-scale Semi-dry Flue Gas Desulfurization System

F. Yu, X. Han, X. Li, H. Jiang, R. Du, Z. Li 527 Analysis and Countermeasures for Fly-ash Feature from Zhungeer Coal with Electrostatic Precipitation

X. Ke, K. Liang, X. Cheng, H. Hu 531 High Dust Concentration ESP for Coal-fired Boiler of 300 MW Generator

H. Xie, P. Ming, H. Ding 534 ESP Application on Combustion of High-sulfur Heavy Crude Oil

J. Ge, Y. Zhang, X. Xu, Z. Shen, P. Zhang 537 Regarding the Selection, Operation and Maintenance of Booster Fan

X. Wang. J. Ge, F. Tang, F. Yang, B. Li, G. Feng, L. Fei 540 The Application Practices of the Double-zone ESP in Coal-fired power Plant

H. Zhang, L. Meng, R. Zhang, J. Guo 543 Industrial Applications for Steel Industries Successful Application of Longking Bf-ESP Technology in Brazil GA Steel Plant

Z. Zhong, H. Song, J. Zheng 549 Characteristics and Technical Improvement Investigation of Electrostatic Precipitator before Sintering Machine

J. Kang, J. Wang, R. Guo, K. Wang 553 Testing and Analysis of Coal Gas Dehydration Equipment in Combined Cycle Power Plant

L. Xiao, Z. Ding 557 FGD and SCR for Coal-fired Power Plants Development of New Gas Cleaning System with Salt Solution Spray

Morio Kagami, Toshihide Noguchi 563 Numerical Investigation of the Entire Boiler System with SCR De-NOx Reactor

X. Cheng, B. Jin 567 Research on Complex Multi-pollutants Control Technology in a Large-scale Coal-fired Power Plant

X. Han, X. Li, M. Liu, H. Jiang, Y. Han 572 New Concept of CFB Boiler with FGD

X. Pan 576 Dry FGD Technology Research and Application in Steel Sintering

J. Zheng 578 Design and Application of Inlet nozzle of Dry Desulphurization ESP

Q. Zhan 581


The Proposal Comparison of Absorbent Preparation System of Wet Limestone-gypsum Flue Gas Desulphurization Process D. Yan 585

Economic Analysis of Wet Flue Gas Desulphurization Project Operation Y. Dai, Y. Shu 589

Discussion on the Mechanism of Semi-dry Desulphurization J. Ge, Y. Dai 593

Analysis on Chimney Inner Wall Anti-corrosion in GGH Eliminated Wet Desulfurization System P. Zhao, K. Wang 597

Simultaneous Removal of SO2 and NO2 by Wet Scrubbing Using Limestone Slurry R. Guo, X. Gao, Z. Wu, Z. Luo, M. Ni, K. Cen 602

Study on Mid-temperature SCR DeNOx Catalyst under High SO2 and CaO Y. Dai, Y. Cui 606

Research and Application of Numerical Calculation Methods in SCR DeNOx Reactor & Duct Design H. Chen 611

Retrofit project of 2×100 MW Units in Yushe Power Plant, Shanxi Province Using Tow Boilers-one CFB FGD F. Lin, E. Lian 616

Design and Application of the Dry-FGD Process in Sanming Steel No.2 Sintering Plant Z. Yu, Q, Li, H. Xu, C. Lin 620

The Fouling Characteristics and Comparative Analysis of Cleaning Technology of SCR Y. Gu, B. Jin, G. Xiao 624

Non-Thermal Plasmas AC/DC Power Modulation for Corona Plasma Generation

A.J.M. Pemen, T.H.P. Ariaans, Z. Liu, E.J.M. van Heesch, G.J.J. Winands, Keping Yan 629 Development of the PPCP Technology in IEPE

J. Zhao, X. Ren, B. Wang, Y. Wu, R. Yang, G. Tu, Y. Zhang 633 Non-thermal Plasma Processing for Dilute VOCs Decomposition Combined with the Catalyst

Tetsuji Oda, Hikaru Kuramochi, Ryo Ono 638 Performance Characteristics of Pilot-scale NOx Removal from Boiler Emission Using Plasma-chemical Process

Hidekatsu Fujishima, Tomoyuki Kuroki, Atsuyoshi Tatsumi, Masaaki Okubo, Keiichi Otsuka, Toshiaki Yamamoto, Keiichiro Yoshida 644

Experimental Investigation on Styrene Emission with a 1000m3/h Plasma System X. Zhang, J. Zhu, Y. Huang, K. Yan 649

Streamer Corona Plasmas and NO Removal X. Hu, X. Jiang, K. Yan , R. Li 653

Influence of Ratio of NO/NO2 on NOx Removal Using DBD with Urea Solution Yusuke Kudo, Hiroshi Taguchi, Sumio Kogoshi 657

Catalysis-assisted Decomposition of Aqueous 2,4,6-Trinitrotoluene by Pulsed High Voltage Discharge Process H. Chen, Y. Shi, L. Lei, Y. Zhang, H. Chu, R. Yang, Y. Zhang 661

Plasma-catalytic Removal of Formaldehyde in Atmospheric Pressure Gas Streams H. Ding, Z. Zhang 665

Relationship between Discharge Electrode Geometry and Ozone Concentration in Electrostatic Precipitator Yoshiyasu Ehara, Daiki Yagishita, Toshiaki Yamamoto, Akinori Zukeran, Koji Yasumoto 670

Study of Carbon Monoxide Oxidation by Discharge Nobumitsu Matsui, Yoshiyasu Ehara, Toshiaki Yamamoto, Akinori Zukeran, Koji Yasumoto 674

Application of a Dielectric Barrier Discharge Reactor for Diesel PM Removal Shuiliang Yao, Satoshi Kodama, Shin Yamamoto, Chieko Mine, Yuichi Fujioka, Chihiro Fushimi 677

Catalyst Size Impact on Non-thermal Plasma Catalyst Assisted DeNOx Reactors M. Chen, Adrian Mihalcioiu, Kazumori Takashima, Akira Mizuno 681

The Study on Series of Copper Catalyst in the Reactor of Dielectric Barrier Discharge to Remove NOx M. Chen, L. Yan, X. Wang, T. Takashima, A. Mizuno 685

VOC Removal Using Adsorption and Surface Discharge Yujiro Oishi, Yoshiyasu Ehara, Toshiaki Yamamoto 690

A Novel Concept of Remediation of Polluted Streams Using High Energy Density glow Discharge (HEDGe) Alex Pokryvailo 694

CONTENTS 7

Gaseous Elemental Mercury Oxidation by Non-thermal Plasma H. Li, T. Zhu, P. Tang, X. Xing 699

A Multiple-switch Technology for High-power Pulse Discharging Z. Liu, A. J. M. Pemen, E. J. M. Van Heesch, Keping Yan, G. J. J. Winands, D. B. Pawlok 704

Humidity and Oxygen Effects on Dimethyl Sulfide Decomposition by a Plasma Corona Reactor J. Chen, Y. Shi, H. Pan, Q. Su 709

The Mechanism of Naphthalene Decomposition in Corona Radical Shower System by DC Discharge X. Gao, X. Shen, Z. Wu, Z. Luo, M. Ni, K. Cen 713

Surface Modification of Polestar Fabrics by Non- thermal Plasma for Improving Hydrophilic Properties S. Inbakumar, A. Anukaliani 718

Predictive Model of Nonequiliburium Plasma Decontamination Efficiency for Gaseous Pollutant Z. Li, Z. Hu, X. Yan 723

Applied Electrostatics Application Study of Electrostatic Precipitation with Earthed Atomizing Discharges

J. Mi, D. Xu, C. Hao 729 Integrated Clarification Technology for De-dusting, Desulfurization and Odor Elimination

Q. Huang 733 Introduction of High Precision Charging Technique Applied in Pulsed Magnetron Modulator for Industrial Computerized

Tomography System Y. Zhang, X. Ren, G. Tu, X. Li 737

Discrepant ESD-CDM Test System and Failure Yield Prediction between ESD Association and JEDEC Standards Yuparwadee Satirakul, Tanawat Butgnam, Pavittra Jittsuntisuk, Surapol Phunyapinuant 740

World-Wide Review

Development of Chinese Electrostatic Precipitator Technology 3

Development of Chinese Electrostatic Precipitator Technology

LIN Youwen, LIU Weiping

(Committee for Electrostatic Precipitator, Wuhan, PR China)

Abstract: In this paper we review the development of Chinese Electrostatic Precipitator (ESP) in the passed 20 years, introduce the recent situation of our country’s ESP technology and forecast the development prospect of ESP in China. Keywords: Electrostatic Precipitator, ESP technology, technology development, technology progress

1 INTRODUCTION

In the second international conference of electrostatic precipitator held in November 1984 in Japan, the author wrote the paper named Development of Electrostatic Precipitator in China and made a presentation on the conference at the invitation from Mr. S. Masuda.

In the early 1980s, the ESP technology in China is in the primary stage, when the world’s ESP technology had become mature commodity. Only more than 20 factories make body of ESP and power source. The ESP value output of 1982 was less than two hundred million. The biggest sectional area of ESP set in 1983 was 220 m2. Most of the sectional areas were less than 100 m2 in 1983, and ESP were mainly applied in industrial sectors such as steel industry, cement industry, chemical industry and papermaking industry.

Two and a half decades passed. Technology and industry of ESP in China have made a great progress. There are more than 200 organizations, which are engaged in ESP and its relevant industries. These organizations have formed an industry with considerable scale. Research, design, manufacture, installation and debugging are all involved in the field of ESP. And the industry covers colleges and universities, research and design institute and enterprises. Now there are there ESP body corporations whose annual processing capacity can be more than 100 thousand tons, more than 10 corporations whose annual processing capacity can be in the range of 30 thousand and 100 thousand tons. There are 3 power source corporations which can make 1000 power sources per year, more than 10 corporations which can make 300 to 1000 power sources per year.

By 2007, the whole contract value of the 21 ESP body corporations has reached 148765211 thousand Yuan, sales value has reached 8852699.8 thousand Yuan and export value has reached 919486 thousand Yuan. As the marketing requirement becomes larger and larger, in 21 century, output value of ESP in China increases dramatically.

Production and management situations in recent years of 13 key enterprises, whose sales incomes are most, are showed in Table 1.

Table 1 Production and management situations of 13 key enterprises in recent years

Year

Industrial Output (10000 yuan)

Sales Income (10000 yuan)

Export Value (10000 yuan)

Increase Amplitude

(%)

2000 182086 139215 5652 2001 213017 175165 4686 25.82 2002 287098 214693 7745 22.57 2003 335288 283102 7825 22.54 2004 428246 392698 11310 27.88 2005 638600 502166 15710.2 27.22 2006 764290.4 574358 60661 14.38 2007 1214291.9 730137 83720 27.12

In a conclusion, ESP in our country has a late beginning

but rapid development. National economy has developed rapidly since the

reform and open-door policy being carried out, which provides broad market for the application of ESP. By the end of the last century, our country has become a great ESP power in the world. China has a large ESP production and using amount. ESP made in China not only meets the domestic requirement, but also be exported to decades of countries. Now the ESP industry has become one of competitive industries in Chinese environmental protection industry.

ESP applied in power plant is the most important part. Only several power plants used ESP before 1980. Quantity of ESP applied in power plant increased constantly from mid 1980s. Electric power industry became the biggest user of ESP after 1990. ESP quantity applied in power plant makes up 75% of total ESP quantity in China. From 1990 to 2000, dust emitted from power plant was kept below 4000000 ton while total thermal power units increased from 76011 MW to 220000 MW. ESP toke an important role in power plant dust treatment.

ESP applied in power plant in our country has a late beginning. The first ESP matching 300000 WK unit was set in Jiangsu Jianbi power plant in 1983; the first ESP matching 600000 WK unit was set in Anhui Pingyu power plant in 1989; the first ESP matching 900000 WK unit was set in Shanghai Waigaoqiao power plant in 2001; the first ESP matching 1000000 WK


unit was set in Zhejiang Yuhuan power plant in 2006. According to this, the application of Chinese ESP is later

than developed countries by 15 to 20 years. As the requirement of the market, especially the requirement of electric power industry, ESP technology in China has become the biggest ESP power in a short time.

So far, there are 10 enterprises which can produce ESP for 600 MW units in China, including Zhejiang Feida, Fujian LongKing, Lanzhou Electric Power Equipment Manufacturer, Tianjie Group, Shanghai Metallurgical & Mining Machine Manufactory, Zhejiang Sunyard, Shanxi Electric Power, Anhui EE, and Zhejiang Luzhou Environmental Protection. Enterprises which can produce ESP for 1000 MW units are Zhejiang Feida, Fujian Longking, Lanzhou Electric Power and Tianjie Group.

According to our statistics until Apr 2008, 17 ESPs for above 600 MW units were put into use before 2000, and the number increased several times after 2000. 220 ESPs for 600 MW units have been equipped, 102 are being manufactured and 108 are being designed. There are 2 ESPs for 900 MW units. And 10 ESPs for 1000 MW units have been equipped, 9 are being manufactured and 29 are being designed. There are much more ESPs for 20 MW–30 MW units. All these data indicates the fast development of ESPs in China.

2 DEVELOPMENT

China initiated ESP technology study in 1965. 3 m2–60 m2 two-field nine-series ESP designed in 1973 was centralized reflection of Chinese research results. It should be noted that, in late 1970s, Yuanbaoshan power plant introduced 173 m2 ESP form Ruthmuhle of German, and Wuhan Steel Fireproof Factory introduced 81.9 m2 ESP form Elex of Swiss. Those successful applications attracted great attention in China.

In Seventh Five-year Plan Period, our country listed “study of high efficiency ESP technology” into the National Key Project, greatly improved Chinese ESP technology and shortened the difference of foreign advanced level.

The most widely used horizontal ESPs and single-phase power sources in China are called conventional ESPs and conventional power sources.

After operation of more than 20 years, many enterprises of sales beyond a hundred million yuan sprung up in Chinese ESP industry. ESPs of Zhejiang Feida and Fujian Longking obtained the title of China Top Brand.

The development of technology and challenge of new emission standards encourage us to take seriously. Electrostatic Precipitation Committee paid great attention to technology development and innovation. From the foundation in 1985, ESP Committee hosted 12 nationwide academic conferences and 10 power source symposiums, and had more than 1000 papers.

Colleges, universities and scientific institutes are the main force of innovation in China, and the strong support of ESP development. The mechanism of ESP also develops, such as: data processing for flue gas characteristic and fly ash size, collection mechanism, bipolar charged collection for

high resistivity fine particles, high concentration dust forced collection, agglomeration, magnetic enhanced atomization corona discharge for flue gas clean, airflow distribution in ESP and numerical computation, airflow distribution in wet ESP and simulation of skewed gas flow technology, effect of trough plate to the airflow distribution, suitable rapping and sound wave dust cleaning, flue gas conditioning, development of design software, simulation of ESP optimal control, ESP help system software, computer data collection of ESP, etc.

These technical innovations, will further improve the understanding of ESP theory, exploit the potential of ESP, and maximize the advantages of ESP. On the basis of independent research and overseas successful experiences, Chinese ESP technology is developed in the practical applications, as indicated below:

2.1 ESP 2.1.1 Lentoid ESP

Lentoid ESP was developed by Wuhan Science & Technology University and Wuhan University. This ESP has good hydrodynamic and electric performance with positive, negative corona electrode and lentoid electrode. The special of this ESP is the electric wind pass through the lentoid electrode, which can decrease the reentrainment and increase the migration velocity of particles. The results of ESP in the concrete plant shows that this ESP can save rolled steel (above 1/3).

Fig. 1 Structure of Lentoid ESP

1. corona electrode 2. collection plate 3. lentoid electrode 4. collecting chamber 2.1.2 Tubular ESP

The tubular ESP was developed by Xi’an heavy Machinery institute and Yuqing science & technology co. Ltd. The positive and negative electrode are used bar tubular and the barbed electrode respectively. In addition, this ESP also has tubular auxiliary electrode. The raping system is a floating structure. The characteristics of this ESP are as follows: (1) higher migration velocity of the parcitle; (2) colleting positive particles; (3) the resistivity of the collection particles follow the the range of 103 ·cm––5×1011 ·cm; (4) has wider operation conditions; (5) larger specific collection area and high efficiency.

Application: The emission concentration of particles in the glass boiler and sintered ESP are 5 mg/m³ and 30 mg/m³ respectively.


Fig. 2 Schematic Diagram of Tubular ESP

2.1.3 Cylinder ESP

Cylinder ESP was developed by Xi’an heavy Machinery institute, Xi’an Xikuang environmental protection Company and Xuanhua metallurgic environmental protection Company. This ESP is a critic apparatus in the convertor flue gas purification. The main component of the convertor flue gas is coal gas which has the risk of explosion. In order to prevent the coal gas and the atmosphere mixing in the ESP chamber, it is the best way to pass through the ESP as laminar flow without circumfluence. Consequently, the ESP was designed to cylinder.

The structure of the cylinder ESP is the same as the horizontal ESP, the inlet and outlet of are taper shape. The pressure impulsion of the ESP chamber 0.3 MP, and the emission concentration is 0.2 mg/Nm3 greatly less than 10 mg/Nm3.

Fig. 3 Schematic Diagram of Cylinder ESP

1. horn shape inlet 2. explosion safe valve 3. electrode 4. ESP shield 5. tach 6. heat preservation box 7. dust scratch

8. dust transport engine 2.1.4 Roof ESP

The roof ESP is a light type build on the roof of the workshop, and mainly used in stove second flue gas purification. The second flue gas has characteristics of large volume of gas, small particle mean diameter, stochastic diffusion, fluctuation of concentration and temperature.

The characteristics of roof ESP developed by Beijing metallurgy construction institute and Wuhan security

environmental protection institute are as follows: build on the roof of the workshop, no need of the land area; operate stably; high efficiency with the wet rapping low energy consume (flue gas float through the electric field itself by the flotage); low maintenance costs low invest costs.

Fig. 4 Schematic Diagram of Roof ESP 1. fan for the insulator 2. high voltage power 3. water supply device 4. insulate box 5. water nozzle 6. collection plate 7. discharge electrode 8. water collect flume 2.1.5 Five-fields ESP

The five-fields ESP is developed by the Xi`an Yuqing Science & Technology Company. The schematic diagram of this ESP was shown in Fig. 5 and the characteristics as follows: (1) gas distribution and particle collection are ongoing at the same time in the pre-charge area; (2) collect the positive and negative particle; (3) charge repeating (especially in the high concentration particles area); (4) increase the collection efficiency of fine and light particles; (5) decreasing the reentrainment of light and fine particle; (6) the five fields can be combined flexible; (7) especially suitable for the old ESP. The results of the rebuilt project of sintered two-field ESP show that the emission concentration is less than 40 mg/m³.


2.1.6 High concentration dust removal with ESP The inlet concentration is 700 g/Nm3–1200 g/Nm3 and

the working pressure is –800 Pa –1500 Pa of the ESP with DFGD in the cement production process.

The problems of treating high concentration dust removal are as following such as fixing equipment of pre-dust removal, air distribution and guide device reasonable, matching electrical apparatus parameters for electric field and the corona blocking, the development of new de-dust, the structure strength and the air leakage.

Fig. 5 Schematic Diagram of Five-field ESP

1. positive electrode 2. auxiliary electrode 3. gas distribution and collection electrode 4. charge repeating 5. rotate collection electrode

Fig. 6 Schematic of ration dust removal with ESP

2.1.7 Application of ESP in machines and electricity with multimode and double-zone The charge area and the Dedust area are independent in

the ESP of machines and electricity with multimode and double-zone exploited by FUjian Longking Environment Corporation

The de-dust efficiency of BES102-4 in 2×130 T/n was up to 99.93% and the exit concentration was 27.4 mg/Nm3.

Fig. 7 ESP with Multimode and Double-zone

Fig. 8 Electromagnetism ESP 2.1.8 Electromagnetism ESP

The trajectory of charged particle was changed in magnetic field and the charged particle turned to collect plate and separated from flue in Electromagnetism ESP.

The Electromagnetism ESP developed by Qinghua tong fang Environment Company has high efficiency and lower consumption.

The inlet concentration is 39 g/m3 and the outlet concentration was 48 mg/m3 in CK -45 with 40 T/n Electromagnetism ESP.


2.1.9 Steel brush ESP It is difficult to removal the glutinous, small bulk density

dust, the steel brush was moved to clean the ash in the plate and wires.

There were several tens steel brush ESP developed by Angang design institute, and their drive speed can up to 50%-100%.

1 anode plate, 2 cathode wires,3 cathode rapping deceleration motor, 4 anode rapping deceleration motor, 5 brush bracket hoister, 6 controller, 7 wire rope, 8 trail rope, 9 brush bracket, 10 anode steel brush, 11 cathode steel brush, 12 dust hopper, 13 ESP shell

Fig. 9 Schematic of Steel Brush ESP 2.1.10 P-FF hybrid precipitator

Although the ESP and FF precipitator also have mature technique, they also have the disadvantages. The ESP has the characters such as lower resistance and maintenance; treating high temperature flue and firm structure, but it was difficult in high resistance. The efficiency of FF precipitator can be up to 99% used the appropriate filter material, while the disadvantages are the high resistance; high power consumption and high maintenance. The ESP-FF precipitator has the both advantages and no disadvantage of ESP and FF precipitator.

The ESP is the first precipitator; it can collect the 80% dust then decrease the de-dust pressure of FF precipitator and the abrasion of filter material. The charge effect of the former electric filed can enhance the characters of breathable and ash removal, it decreased the resistance and filter areas, it also increased the lifetime of filer bag and pulse valve then decrease the cost of maintenance.

The ESP-FF precipitator had the noticeable de-dust effect in the transformation program since the first one operated in Fujian Longjing. The ESP-FF precipitator is the best choice in the condition of high resistance.

The wet-ESP had also been developed expect above ten ESP technology as well as flue adjustment. The move plate ESP and INDIGO coagulation developed with foreign country also got success, plenty of develop working had done in the matching of plate and wire such as the corona wire used to decrease electric blind area, the fishbone needle and field specific resistance tester.

Fig. 10 ESP-FF hybrid precipitator

2.2 Power Source Technology

Dedust process in ESP is based on the principle of electrical physics. ESP has developed for more than 100 years with few technical breakthrough. But the state of art of power source technology may bring an important renovation to ESP.

ESP power source has developed for several generation. The performance of domestic conventional power source is similar to products from oversea.

To realize the goal of energy saving and emission reduction, Chinese researchers made an effort to do lot of friable work. Pulse power source and wised dynamic optimized control system have been developed according to the regulation between dust collection and electrical parameters. Based on this, emission can be reduced by more than 30% and energy can be saved by more than 70%.

These years, conventional power sources have been improved in China. Meanwhile, research and development of new kind power source are ongoing. 2.2.1 High Frequency High Voltage Rectifier

Up to now, Longking Environmental Protection Corp., Wuhan Guoce high tech Corp., Zhejiang Jiahuan Corp., Longyan Longmen Corp., have developed high frequency high voltage rectifier respectively.

Take Longking Environmental Protection Corp. as an example, its SIR power source adopts AC-DC-AC technology. Soft switch technology is used for protecting the inverse switch. Different resonance matching parameters are used for different sepecification of power source.

Longking has also developed a high power convertor, which give priority to full-bridge resonance part parallel resonance. The mixed topological structure can satisfy the requirements of continuable spark discharge and impact, and large scale load variety.

The problems of high power convertor and high frequency high voltage have been solved by nano-crystalline high-frequency high voltage transformer and self-developed large current high frequency high voltage silicon rectifier stack. The developed high frequency high voltage rectifier has passed the tests of bad environment and complex operating condition.

There are two kinds of power supply for control system, one is DC supply, the other is intermittent supply. And the control system has good control and protection functions: integration of high voltage and low voltage, rapping control program, power off rapping and back-corona auto-detecting and control, remoting control function.


Fig. 11 Schematic of high frequency power source

2.2.2 Three phases silicon-rectification power source Xiamen Lvyang Corp. and Jinhua Zhonghe Corp. have

developed three phases silicon rectification power source, which using full wave rectification. Electricity, from electric grid Y308V/50HZ enter the rectification, then stepped up by three phases transformer. After second rectification, the three phases high voltage will be added together on the discharging electrode of ESP.

The three phases silicon-rectification power source is good as single phase power source at the aspects of control and management function, spark control, and network monitoring. The two are compatible with each other. Compared with the latter, three phases silicon-rectification power source has other characteristics as follows:

(1) High conversion efficiency. The power factor is larger than 95, results in the small electric grid loss.

(2) High voltage output. Secondary voltage from three phases silicon-rectification power source is high. So the charge ability of dust and collection efficiency can be improved.

(3) Prominent energy saving if super high power setup is used. Primary current output of Single phase power source 2.0/72 kV is 541 A, but 230 A for three phases power source.

After using three phases power source in a aluminum production factory, its dust emission concentration is decreased from 600 mg/Nm3 to 57 mg/Nm3 and 37 mg/Nm3.

In the electric reconstruction of 60 kW unit in a power station. Three phases power source was used on the first field, and intermittent power supply for others. The emission concentration was decreased from 130 mg/Nm3 to 50 mg/Nm3. Energy was saved by 60%.

Fig. 12 Schematic of three-phases high voltage control

2.2.3 Three phases intermediate frequency DC high voltage power source

Intermediate frequency power source has the characteristics of both SCR power source and high frequency power source: low switch wastage, high power, small volume, good performance and technical environment. Large quantity

Circ

uit b

reak

er

Con

tact

or

Rec

tifie

r

Pow

er fa

ctor

regu

lato

r

DC

Pow

er

Full-bridge serial-

connecting resonant circuit

Part parallel-connecting

resonant circuit

High frequency

transformer High

frequency rectifier

DC high voltage

Output

Charging setup circuit

Pulse driver protection

circuit Feedback

sampling circuit

CSM controller

Communication distributing

board

Upper computer

Terminal operation

display board

Several assistant circuit;

Temperature detection containing control circuit;

Rapping control circuit;

Cooling fan auto-control i i

Double CPU computer controller


of this kind of power source can be produced with low cost in a short time and replace the SCR power source. Zhejiang Jiahuan Corp. and Wuhan University hve developed a kind of intermdiate frequency power source jointly:

(1) Operated under AC-DC-AC-DC, three phases high frequency adverse transform, intermediate 400Hz rectification. The work efficiency is improved obviously. Volume and weight of the power source is decreased, and output wave is more flat.

(2) Using IGBT module as switch, and double CPU as the core of control system,(TMS320F2812 from TI Corp. is used in operating control system, and ARM controller is used for monitoring). Several power sources constitute a control network and communicate with CAN or RS485.

(3) 0.21 mm–0.27 mm silicon steel is used as the core of transformer. Normal electrical wire and silicon stack are used as string wire and rectifying bridge. /Y three phases winding and three phases rectfication. The volume and weight are much smaller than SCR power sources.

(4) Illegible PI (proportion integration) control method is used in stable voltage and current control system, and realize astatic control of voltage/current. SVPWM adverse transform technology is used for current transformation control, and realize three phases symmetry intermediate frequency AM and FM. In that way, switch wastage is small and DC current utilization can be improved. The output can be Stable DC wave and intermittent wave.

(5) Excellent protection function makes power source reliable.

(6) Control cabinet and transformer can either be separated or integrated.

The primary tests showing high dust removal efficiency and energy saving of power source. The practicality needs further verifying.

Fig. 13 Mechanism of Three Phase Medium Frequency Power Source

2.2.4 LC HVDC current power source

Shanghai Power Equipment for Laser Co., Ltd develops a HVDC Current Power Source. The mechanism of power source is rectifying line frequency of single phase output with L-C control cabinet and then converting to high voltage to load through transformer.

As indicated in Fig. 13. The condition of constant voltage, constant current and optimal discharge sparkle ratio is control by L-C circuit. Voltage is a random parameter.

Current is set according to requirement and unaffected with electric field.

Thus, automatic tracking of high voltage can be realized. The above characteristics are benefit to obtain high operation voltage, enhance corona power and apply in complicated working condition.

Fig. 14 Mechanism of HVDC Current Power Source

2.2.5 Development of plasma source Plasma dedust and DeNOx/SOx is a promising

technology which needs high frequency , sharp rising, and narrow pulsed high voltage supply. However, the previous pulsed power source can not meet the demand of dedust and DeNOx/SOx industry application.

AC/DC power source is an innovation streamer corona generator which is developed with several years of exploration and experience accumulation. This newly technique is realized by modulating a high voltage DC on high frequency AC and turning the glow corona to high efficient streamer corona.

The AC/DC system is consisted of high voltage DC, high voltage AC and AC/DC coupling circuit. AC and DC are all worked with resonant means through three-step process. In the first step, line frequency input is rectified with three-phase full-bridge controllable circuit. During the second step, the output from first step is filtered with a LC circuit. Then the filtered current is inverted into high frequency AC with a single-phase full-bridge inverter circuit which is composed of IPM and converted into high voltage with a transformer. The DC output is connected with a full-bridge rectifier.

The largest industrial application of AC/DC streamer discharge system for abating NOx/SOx (50 WM unit) is developed by Guangdong jiete Technology Co., Ltd and Guangdong Jiade Environmental Protection Co., Ltd.


Fig. 15 Schematic of AC/DC Power Source

2.2.6 High frequency inverse DC (rectangle characteristic) power supply

Shijiazhuang Tuowei technology Co., Ltd develops a high frequency inverse DC power supply. Its rectangle VA characteristic can meet the following demands of high voltage ESP:

(1) Unaffected by long term short circuit and open circuit operation.

(2) The dust concentration can be automatically tracked when operation point is on vertical line of rectangle.

(3) Saving energy. The rectangle VA characteristic is produced by double-

closed-loop error. By regulating Ui value, the horizontal line of rectangle can be changed, thus setting safety operation voltage Uom. By regulating Ui Ii, the vertical line of rectangle can be changed, thus tracking operation point.

Almost a hundred dedust projects indicating the F type power source has stable running, high reliance and excellent energy saving properties. According to running datum of Shougang group and Shuangliang group, F type power source can save about 90% and 40% of energy and steel respectively compared with traditional optimal discharge sparkle ratio dedust system.

Fig. 16 Mechanism of High frequency inverse DC power source

Besides above mentioned, pulsed power supply has also been developed. Almost no breakthrough progress was made in last 30 years for single phase power source. However, various power supply modes have been innovated to meet the

requirement of domestic market, such as highest mean voltage control, optimal discharge sparkle ratio control, critical sparkle tracking and low voltage control of PLC and DCS et al.. The collected datum transportation are also developed as field bus, ethernet network and OPC ports et al.

2.3 Associated Equipment and Technology

Excellent ESP equipment, not only needs a good body and superior electricity-supply technology, but also needs fine accessories. With the development of ESP technology, the accessories are also making progress.

There are more than 30 corporations in China to make accessories related to ESP industry, including electrode plate, electrode wire, insulation, sound wave dust-removal, level indicator, isolation switch, speed reducer gear, cinder valve, bearing ect. The following part will highlight two accessories, insulator – Longtai 95 ceramics, and SQ series sound wave dust-removal.

2.3.1 Tailong 95 ceramics

Tailong 95 ceramics are produced by the Nanjing Tailong Special Ceramics Company. Al2O3 (purity of 95%) is formed by uniform static pressure technique and then calcinated under 1600 -1700 . The products have strong mechanistic strength and resistance against high temperature and drastic vibration, 4-6 times higher than the normal electric ceramics. Their volume have been greatly reduced under the same condition. The main specialty of the product is of high resistance at high temperature, 109 ·cm under 400

, but for normal electric ceramics, its volume resistivity will drastically reduce to 108 ·cm under 150 200 . Tailong 95 ceramics’ excellent electromechanical performance under high temperature can maintain insulation requirement of all kinds of ESP. Their performance index has achieved or exceeded that of foreign products, but 1/2-2/3 lower price. So far they have been widely used in many domestic ESP equipments, some have been exported to Australia, America, Korea.

2.3.2 SQ series sound wave dust removal

The products are manufactured by Liaoning Zhongxin Co., Ltd. Their sound wave is produced by vibration filmstrips and the drive force is compressed air. The working pressure has a wide span and sound wave level index is also very high.

Table 2 SQ main technical parameters and a

compare with other products

Type Zhongxin Co.,

Ltd. Foreign product

Domestic product

Frequency Hz 75-280 220 30-70 Sound pressure db 145 143-145 135-145

Sound resource MPa

0.3-0.7 0.4-0.55 0.3-0.6

Air consumption m3/min

1.5-2.95 12-2.4 1.5


The products have been widely used in the steel industry, electricity industry and many other fields. They have many advantages, wide working space, good dedust efficiency, easy fixture, and low price. After application of the sound wave dust-cleaner, the dust emission concentration has been greatly reduced, from 247 mg/Nm3 and 235 mg/Nm3 to 58 mg/Nm3 and 46 mg/Nm3, respectively.

3 OUTLOOKS

Along with the acceleration of the process of urbanization and industrialization, energy industry and material industry need faster development. According to the 11th Five-year Plan, 165 million kilowatts are arranged during this period. Total electrical install capacity will achieve 650 million kilowatts till 2010, and coal-fire power will be 87 million kilowatts. During 11th Five-year Plan, cerement will increase 400 million ton. So the environmental protecting

industry has a wide developing space. Serious air pollution control should be emphasized. On one hand, coal takes more than 70% in our energy structure, in the other hand, our extensive development mode needs a higher energy consumption. Coal-smoke air control provides a good chance to ESP to be widely used.

In order to improve equipment and energy utilization ratio, power plant and unit capacity is developing to 600000 kW and 1 million kW super-critical units. Cerement industry is also developing to 5000 ton/day, 10000 ton/day, and 12000 ton/day. All other industry equipments are also becoming macro-scale. Undoubtedly, ESP equipments are the main dedust apparatus for the macro-scale devices.

As the emission standard is improving, original ESP equipments need to be rebuilt. Of course, this is a heavy duty and there is much work for us to do in the field of ESP.

11th International Conference on Electrostatic Precipitation

12

Multi-pollutants Simultaneous Removals from Flue Gas

GAO Xiang1, WU Zuliang1,2, SHEN Xu1, LUO Zhongyang1, NI Mingjiang1, CEN Kefa1 (1 State Key Laboratory of Clean Energy Utilization of Zhejiang University, Hangzhou, 310027, PR China

E-mail: [email protected]; 86-571-87951335 2 College of Environmental Science and Engineering of Zhejiang Gongshang University, Hangzhou, 310012, PR China

E-mail: [email protected]; 86-571-87951434-8415)

Abstract: With the stricter emission standards, more pollutants in the air need to be controlled. If the traditional mean of using a technology to treat a pollutant is adopted, there are high investment running cost and complex operation system. So the multi-pollutants simultaneous removal technology from flue gas is paid more and more attention in the recent ten years. The plasma technology and semi-dry flue gas cleaning technology are two very promising multi-pollutants simultaneous removal technologies. In our researches, a plasma technology of corona radical shower and a semi-dry flue gas cleaning technology using circulating suspension and multistage humidification were selected. A series of fundament and industry application works were done. In the paper, some current results are opened out to provide some reference. Keywords: Multi-pollutants, simultaneous removal, plasma, semi-dry

1 INTRODUCTION

China is the largest exploiter and consumer of coal in the world. Since the 1980s, coal consumption has continuously grown by 4%-9% every year, which produced various atmosphere pollutants including dust, SO2, NOx, heavy metal, etc. The annual economic loss only caused by acid rain exceeds 100 billion RMB. Coal is mainly used for power plant boilers, industrial boilers and industrial furnaces in China. So these boilers and furnaces become the emphases treatment objects. According to the statistic, 25.49 million tons of SO2 was emitted in 2005. What’s more serious, the emission of SO2 reached 25.888 million tons in 2006. NOx emission is increasing year by year. The total amount of NOx emission has been more than 18 million tons currently. If some effective measures don’t taken, NOx emission will reach 30 million tons after ten years. Some reports show that the average NO3- concentration of the precipitation in the 1990s is 2.1 mg/L. However, it is 2.8 mg/L from 2000 to 2003. Equivalent concentration ratio of NO3- and SO4

2- of the precipitation also presented an upward trend since 1999. It is 0.17 in 2003, the highest value in the last 14 years [1,2].

To prevent air pollution from becoming worse, many law, statute, policy and standard have been established. “The Outline of the Eleventh Five-year Plan for National Economic & Social Development of the PR China” (hereinafter referred to as ‘the outline’) claims that energy consumption per-unit GDP must descend 20% and major pollutants descend 10% during the 11th Five-Year Plan in Mar, 2006. To achieve the SO2 control target, the work of energy saving and emission reduction has been emphasized strongly since 2006. In Jun., 2007, a special work group leaded by the Premier, Wen Jiabao, was come into existence to respond to climate change, energy saving and emission reduction. From these actions, it can be appeared that pollutant emission reduction has

obtained unprecedented attention in China. The future energy structure of China will be no significant change. Coal is still the main energy source. China certainly faces the terrible flue gas multi-pollutants control problem.

Through the long-term investigation and engineering practice, the developed countries have basically solved dust, SO2 and NOx emission problem under the existing emission standards. The corresponding control equipment has been widely used. In China, dust collector and DeSO2 from flue gas have already had a good application. The research and industrial application of flue gas DeNOx have been underway on the support of overseas technology. However, for multi-pollutants reductions from flue gas, the commonly adopted pathway is that these pollutants are treated respectively using different processes, e.g., SO2 reduction by wet flue gas DeSO2 (WFGD) and NOx reduction by selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR). Subsequently, high investment cost, large installation space and complex system will appear. This is a headachy problem for some developing like China. Fig. 1 shows the traditional pollution control combination system from flue gas.

Fig. 1 The traditional combination techniques for flue gas

multi-pollutants control

To overcome the shortcomings of the existing flue gas pollution control technology, simultaneously controlling two or more pollutants has become a research hotspot at home and

Multi-pollutants Simultaneous Removals from Flue Gas 13

abroad. Some developed countries such as USA, Germany and Japan have carried out very active investigation on the simultaneous removals for multi-pollutants in the recent ten years. Through the long-term effort, some technologies have already been in the early commercialization stage. Currently, the simultaneous removal technologies focus SO2 and NOx mainly. The concrete technologies are as follows: active carbon [3], SNOx [4], SNRB [5], NOxSOx [6], electron beam (EB) [7]. But most technologies are in the demonstration stage due to unripe craft. For example, the EB devices installed in the Chengdu Thermoelectric Plant and Hangzhou Xielian Thermoelectric Plant have been stopped operating because of serious erosion, high energy consumption, ammonia pollution and low running reliability.

In a word, developing a high-efficiency, stable operation and inexpensive multi-pollutants simultaneous control technology is very pressing and necessary. The fundamental theory research needs to be strengthened. We always go on the research on the flue gas multi-pollutants simultaneous removal technology using plasma and semi-dry flue gas cleaning methods since 1998. In the paper, some researching results will be provided to discuss.

2 PLASMA MULTI-POLLUTANTS FLUE GAS CLEAN- ING TECHNOLOGY

Plasma has an important role in treating the complex and toxic pollution gases. It expresses a special ability of non-selectivity for multi-pollutants, high reduction efficiencies and rapid chemical reaction, so using plasma to treat various gaseous pollutants at one time is being paid more and more attention recently. 2.1 Plasma Devices

The core of plasma pollution control technology is how to generate high-activity plasma. Many plasma generation methods have been developed. Some schematics of plasma devices commonly used in a flue gas cleaning system are shown in Fig. 2. The details of principle and nature of each device can be found in many recent reviews [8-12]. From Fig. 2, the plasma can be generated through the following methods: (1) EB; (2) dielectric barrier discharge; (3) corona radical shower; (4) pulsed corona; (5) arc discharge; (6) RF discharge; (7) microwave discharge.

EB and pulse corona are two non-thermal plasma technologies that are earlier and more broadly used for flue gas treatment. However, overmuch energy consumption is always a puzzled problem that restricts their large-scale industry applications. High-energetic electrons from EB or pulse corona are directly injected into the reactor and collided with the main components of flue gas (N2 and CO2), which will lead to much energy waste [13].

In order to improve energy efficiency of plasma technology, Chang et al [14-17] brought forward a corona radical shower (CRS) system. A nozzle electrode was used as a discharge electrode instead of corona wire. Under strong electric field, the stable and intensive corona can be formed

near the nozzle. What’s better, the high-energetic electrons mainly collided with additional gas from nozzle, which makes the energy loss obviously decrease. So the CRS technology was chose for flue gas multi-pollutants simultaneous removal in our research.

Fig. 2 Some plasma devices [12]

2.2 The cRS Multi-pollutants Simultaneous Removal In the CRS technology, a pipe electrode with nozzles

was used as a discharge electrode. Positive DC high voltage was applied to the nozzle electrode where active radicals were produced. Additional gases (O2, H2O, NH3, etc.) were introduced into the pipe and injected into the reactor through the nozzle. Because of intensive electric field at the tip of nozzle, the additional gases from nozzles were dissociated into various active species (such as OH*, O*, O3, etc.). Therefore, more electrons were collided with the additional gas molecules but not N2 and CO2 in the flue gas. As a result, the energy waste will decrease much.

In our research, the simultaneous removals of SO2 and NOx using CRS system can be achieved through two processes according to the different additional gases.

(1) NH3 as the additional gas. In this process, SO2 removal mainly depends on the thermal chemical reactions between SO2 and NH3 [18]. But NOx removal depends on the radical reactions during corona discharge SO2 removal mechanism isn’t given unnecessary details. NOx may be removed through the following approaches:

(a) The direct reduction processes with NH and NH2 produced by NH3 dissociation could take place when NH3 was injected from nozzle electrode. The corresponding reactions are as follows [19]. Comparing with NO, no significant NO2 direct reduction reactions take place with the addition of NH3 [20].

NO+NH=N2+OH (1) NO+NH2=N2+H2O (2)

(b) Since air is used as the balance gas of NH3 in the additional gas, N2 and O2 will be dissociated or ionized to assist direct reduction and oxidation under strong streamer corona. The possible reactions are as follows [19]:

NO+O+M=NO2+M (3) NO+O3=NO2+O2 (4)


14

NO+N=N2+O (5) NO2+N=N2+O2 (6)

(c) Because there is little H2O, the following reaction could be generated [19]:

NO+OH+M=HNO2+M (7) NO2+OH+M=HNO3+M (8) NO+HO2+M=HNO3+M (9) NH3+HNO2=NH4NO2 (10) NH3+HNO3=NH4NO3 (11)

(d) In addition, (NH4)2SO3 and NH4HSO3 generated by the thermal chemical reactions of SO2 and NH3 can also reduce NO2 into N2.

4(NH4)2SO3+2NO2=4(NH4)2SO4+N2 (12) 4NH4HSO3+2NO2=4NH4HSO4+N2 (13)

In the CRS system of NH3 as the additional gas, the final byproducts are dry (NH4)2SO4 and NH4NO3, which can be collected through a ESP or FF. The applicative schematic diagram is shown in Fig. 3.

Fig. 3 The applicative schematic diagram using the CRS

system of ammonia as additional gas

(2) O2 as additional gas. In this process, NO is oxidized into NO2 firstly in the CRS system. And then NO2 can be absorbed by Ca(OH)2 or NaOH. The NO oxidization process can be express as follows [19]:

NO+O+M=NO2+M (14) NO+O3=NO2+O2 (15) NO+OH+M=HNO2+M (16) NO2+OH+M=HNO3+M (17) NO+HO2+M=HNO3+M (18)

However, SO2 is oxidized very little in the CRS system of O2 as additional gas [21]. How to absorb SO2 and these NO oxidized byproducts becomes a hot potato. In fact, many WFGD systems have been operated in China. Considering that NO2 can be absorbed well by alkali solution, if the CRS system of O2 as additional gas is set up before the former WFGD, SO2 and NOx can be removed simultaneously. Furthermore, the whole system can be applied in the reconstruction of the former WFGD, which will decrease investment cost greatly. For developing countries like of China, it is a certainly good idea. The applicative schematic diagram is shown in Fig. 4.

Fig. 4 The applicative schematic diagram using the CRS

system of oxygen as additional gas

2.3 The CRS System of Ammonia as the Additional Gas Some experimental results were given about the

simultaneous removals of SO2 and NOx. SO2 and NO initial concentrations are 205 ppm and 160 ppm respectively. [NH3]/[NO]+[SO2] MR value was 0.5, 0.76, 1 and 1.2 respectively. Fig. 5 shows SO2 removal rate under different MR. It is clear that SO2 removal rate improves obviously without corona discharge with the increasing MR. Under 0.76 MR, SO2 removal rate reaches 76% without corona discharge. After discharge, SO2 removal rate can improve 20%.

0

20

40

60

80

100

120

0 1 2 3 4 5

corona power (W)

SO2

rem

oval

rate

(%)

MR=0.5MR=0.76MR=1

Fig. 5 SO2 removal using a CRS of ammonia

In addition, NO and NOx removal rates under different

MR are also analyzed in Figs. 6 and 7 respectively. With the increasing MR, NO removal rate has not obvious change. For NOx removal, when the MR increases from 0.5 to 0.76, the NOx removal rate increases quicker. With the further increasing MR, the increasing rate becomes slow. The NOx removal rate is 27.5%, 31%, 31% and 31.5% respectively under 3 W power. From the two figures, NO and NOx removal rates depend on the input power. With the increasing power, NO and NOx removal rates improve obviously.

0

10

20

30

40

50

60

70

0 1 2 3 4 5

corona power (W)

NO

rem

oval

rate

(%)

MR=0.5MR=0.76MR=1MR=1.2

Fig. 6 NO removal using a CRS of ammonia


05

1015202530354045

0 1 2 3 4 5corona power (W)

NO

x re

mov

al ra

te (%

)MR=0.5MR=0.76MR=1MR=1.2

Fig. 7 NOx removal using a CRS of ammonia

In a word, the increasing MR can promote the SO2

removal but have not big effect on NO and NOx removal. The corona discharge has some promotion for SO2 removal but NOx removal is dependent on the corona power. 2.4 The CRS System of Oxygen as Additional Gas

In the experiment, the flue gas coming from the reactor is conducted to the NaOH solution (26%), where the NO, NO2 and HNOx contained in the flue gas are absorbed. The gaseous HNOx cannot be measured due to the unavailability of a measuring instrument. Only the NOx in the flue gas needs to be measured on the assumption that gaseous HNOx can be completely absorbed by the NaOH solution.

Figs. 8 and 9 show the change of the NOx concentration after the reactor and the absorption bottle (the curve signed with AB-NOx) with the discharge voltage. The NOx concentration drops after the flue gas passes through the absorption bottle because NO and NO2 are absorbed by the NaOH solution. The transition curve of NOx concentration is analogous with that of NO concentration, this proves that the NaOH solution absorbs NO2 completely and dissolves NO in small quantities.

Fig. 8 NOx reduction in the CSR combined NaOH absorption

under 42% RH

Fig. 9 NOx reduction in the CSR combined NaOH absorption

under 68% RH

Due to being absorbed by the NaOH solution, the NOx decreases to some extent. The overall NOx reduction rate is calculated and shown in Fig. 10. Apparently, the overall NOx reduction rate increases as the discharge power increases. With a corona power of 11W, 81.7% of the NOx is reduced corresponding to a relative humidity of 42%. Only 8W is needed to reduce the same NOx corresponding to a RH of 68%.

Fig. 10 DeNOx efficiency under different power

3 SEMI-DRY MULTI-POLLUTANTS FLUE GAS CLEANING TECHNOLOGY

In semi-dry flue gas cleaning technology for multi-pollutants simultaneous removal, acidity substances such as SO2, HCl, HF are removed by Ca(OH)2-based absorbent from flue-gas and conversed into saline material. Due to the active surface of the absorbent in absorber, NOx, heavy metal and other pollutants are absorbed through physic and chemical reactions.

Composite additives with multi-components and high activity in absorbent can oxidize NO to NO2, and prolong the time of liquid phase ionic reaction. At the meantime, due to the developed stoma configuration and huge inner surface area of absorbent and assistant active carbon, heavy metal and organic compounds are absorbed and removed. Eventually, most pollutants deposite in outcome ash collected by dust precipitator. Fig. 11 is the process schematics of semi-dry flue gas cleaning technology for multi-pollutants simultaneous removals.

Fig. 11 Process schematic diagram of semi-dry flue gas

cleaning technology

3.1 Multi-stage Humidifier Chemical reactions in absorber can be divided into two

stages: constant and deceleration reactions. In constant reaction stage, absorption rate of SO2 is high and fall slowly


16

with time. Therefore, when other parameters (inlet temperature, inlet SO2 concentration, Ca/S and circulation rate) are the same, multi-stages humidifier (see in Fig. 12) are used to distribute water reasonably to avoid over-humid absorbent locally and prolong constant reaction stage and promote DeSO2 performance.

Fig. 12 Schematics of multistage humidifier

The effect of humidifier stages on DeSO2 performance is

shown in Fig. 13. The results indicated that adding humidifier stages can improve DeSO2 efficiency. Considering the factors of drop collision and system complexity, two or three-stages humidifier is recommended in engineering (see Fig. 14).

Fig. 13 Stages of humidifier effect on DeSO2

Single-stage Humidifier

Multi-stage Humidifier

Fig. 14 Status inside the absorber

3.2 Additive with Multi-components and High Activity The microcosmic characteristics and absorptive

capability of absorbent can be promoted by increasing its specific surface area and porosity through hygroscopic and oxidative additive. Hygroscopic additive prolongs the time of liquid drop evaporation and accelerates pollutants absorption. In addition, oxidative additive oxidizes NO to NO2 that can be neutralized by alkali matter. The modified absorbent can improve removal efficiency of mercury effectively.

Fig. 15 shows that specific surface area and porosity of absorbent increases from 22 m2/g to 29 m2/g and 53 to 63 respectively while hygroscopic additive ratio is 1%. They also

increase with the increasing additive. The microcosmic characteristic of improving absorbent is good for its capability of purification.

(a) The Effect of Hygroscopic Additive on Specific Surface

Area of Absorbent

(b) The Effect of Oxidative Additive on Specific Surface

Area of Absorbent Fig. 15 The nature of additive effect on specific surface area

3.3 Simultaneous Removal Using Semi-dry Flue Gas Cleaning Technology

Composite absorbent with multi-component and high activity combined with multi-stage humidifier were used in semi-dry flue gas cleaning technology to control multi-pollutants simultaneously.

The main ionic reactions of SO2 in absorber are listed below:

-2

-2 2 3

- 2-3 3

-2

2 -

2 2-3 2 3 2

3 2 2 4 2

H O H OHSO (aq) H O H HSOHSO H SOCa(OH) (s) CaOH OHCaOH Ca OHCa SO 1/ 2H O CaSO 1/ 2H O(s)CaSO 1/ 2O 3/ 2H O CaSO 2H O(s)

+

+

+

+

+ +

+

↔ ++ ↔ +

↔ +↔ +

↔ ++ + ↔ ⋅

+ + → ⋅

There are some deceleration reactions happened near the outlet of the top of absorber.

2 2 3 2

3 2 4

Ca(OH) (s) + SO CaSO + H OCaSO +1/2O CaSO

→→

Results in Figs. 16 and 17 imply that operating condition affects the purification efficiency and utilization ratio of semi-dry flue gas cleaning technology for multi-pollutants simultaneous removal a lot. The results indicate the lower adiabatic saturation temperature ( T) the higher DeSO2 efficiency. DeSO2 efficiency was above 96% in experiment while 95.7% in practice project.


Flu-gas Volume 1156 Nm3/h, Inlet Temperature 160 , Inlet

SO2 Concentration 2288 mg/Nm3, Ca/S=1.5 Fig. 16 The effect of adiabatic saturation temperature ( T)

on DeSO2 efficiency

Fig. 17 DeSO2 efficiency in practice project.

In absorber, NO are oxidized to NO2 through the

adsorption and catalysis of composite additives with high activity, and then absorbed by ash, additives and calcium-based absorbent. Key NOx removal reactions are listed hereinafter.

Oxidized Calcium-based Absorbent2

2 2 3

2 3 3 2 22- - 2- +

2 3 2 2 4

NO NO3NO + H O 2HNO + NOCa(OH) + 2HNO Ca(NO ) + 2H O

2NO + SO + H O 2NO + SO + 2H

⎯⎯⎯⎯⎯⎯⎯⎯⎯→↔

→

→

Fig. 18 shows the effect of oxidizing additive on DeNOx. In a certain range, the DeNOx efficiency increases with the high oxidizing additive ratio. Fig. 19 shows that the DeNOx efficiency of practice project has reached 41.11%.

0

10

20

30

40

50

60

0 1 2 3 4additive ratio/%

deni

tratio

n ra

te/%

Additive C

Fig. 18 The effect of oxidized additive on DeNOx

Fig. 19 DeNOx efficiency in practice project

Earlier researches indicate that HCl is a key material effecting the transformation of mercury. There are also other influencing factors, such as O2, NOx and SO2. Main reactions of mercury after combustion are as follow:

02 2 2

0

2

2 2 4

2

2Hg (g) + 4HCl(g) + O (g) 2HgCl (g,s) + 2H O(g)

Hg (g) + HCl(g) HgCl(g) + HHg(g) +1/2O (g) HgO(s,g)2SO (g) + 2HgO(s,g) + O (g) 2HgSO (s,g)Hg(g) + NO (g) HgO(s,g) + NO(g)

→

→→

→→

There are none ways suitable for the removal of all three phases of mercury. In semi-dry flue gas cleaning technology for multi-pollutants simultaneous removal, calcium-based absorbent was sprayed into absorber to control mercury phases. Adsorption efficiency of zero-valence mercury in gaseous phase increases by multi-stage humidifier. Divalent mercury is absorbed into liquid drops. Both gaseous phases of mercury are converted into particles, which is beneficial to three phases of mercury removal simultaneously.

Fig. 20 shows mercury reduction varying with time in the different temperature. As shown in Fig. 21, the removal efficiency of divalent mercury efficiency has been to 89.11%, the removal efficiency of total mercury efficiency has reached to 73.1%.

0 20 40 60 80 100 120 1400

10

20

30

40

Fig. 20 Mercury reduction varying with time in the different

temperature

(a) Removal efficiency of divalent mercury

(b) Removal efficiency of total mercury

Fig. 21 Removal efficiency of mercury in practice project


18

4 CONCLUSIONS The flue gas multi-pollutants simultaneous removal is an

inevitable trend in the field of flue gas purification. The CRS plasma technology and multi-stage humidifier semi-dry technology appears a good foreground for flue gas multi-pollutants simultaneous removal according to our previous research. The CRS of ammonia as additional gas can obtain high DeSO2 removal efficiency and medium DeNOx removal efficiency. Additionally, the CRS of oxygen as additional gas combining alkali solution can achieve high DeSO2 and DeNOx removal efficiencies. Furthermore, it is very fit of the reconstruction of primary WFGD. The semi-dry flue gas cleaning technology using circulating suspension and multistage humidification has realized large-scale industry application. It can achieve high multi-pollutants removal efficiency through multistage humidification and improving additive.

ACKNOWLEDGEMENTS

The work is supported by 973 Program of China (2006CB200303), 863 Project of china (2007AA061804), NSF of Zhejiang (Y507079), EOP of Zhejiang (Y200702725) and PSF of China (20080431325).

REFERENCES 1. State Environmental protection Office. Chinese environ-

mental status communique in 2006. 2. Lu Z. The discussion about NOx pollution and control

measure. The paper in academic workshop about City atmosphere pollution prevention and cure of Beijing, 2000.

3. Peng H.H., Hu H.Y., Zhao G.C., et al. The review of SO2 and NOx control technology from flue gas. Guang Xi electric power 2003, 26(4): 64-68.

4. DOE/FE. ABB environmental systems SNOXTM-flue gas cleaning demonstration project, DOE/FE-0395. Knoxville: ABB Environmental System, 1999.

5. DOE/NETL. SOx-NOx-ROx-BOxTM flue gas cleanup demonstration, DOE/NETL-2001/1135. Pittsburgh: National Energy Technology Laboratory, 2000.

6. Zhong Q. Desulfurization and denitrification technology and engineering instance from coal-fired flue gas. Beijing: Chemical Industry Press, 2002.

7. Radoiu M T, Calinescu D I M I. Emission control of SO2 and NOx by irradiation mehods. Journal of Hazardous Materials, 2003, 97(1-3): 145-158.

8. Doi Y, Nakanishi I, Konno Y. Operational experience of a commercial scale plant of electron beam purification of flue gas. Radiation Physics and Chemistry, 2000(57): 495-499.

9. Ogata A, Ito D, Mizuno K. Removal of dilute benzene using a zeolite-hybrid plasma reactor. IEEE Trans. Ind. Appl., 2001, 37(4): 959-964.

10. Li D, Yakushiji, et. al. Decomposition of toluene by streamer corona discharge with catalyst. J. Electrostatics, 2002, 55: 311-319.

11. Oda T. Non-thermal plasma processing for environmental protection: decomposition of dilute VOCs in air. J. Electrostatics, 2003, 57: 293-311.

12. Chang J S. Recent development of plasma pollution control technology: a critical review. Science and Technology of Advanced materials, 2001, 2: 571-576;

13. Hadidi, K., et al., 1996. Commercial possibilities for the tunable electron beam plasma reactor for volatile organic compound treatment. Proceedings of the International Workshop on Plasma Technologies for Pollution Control and Waste Treatment. Beijing, China, 106-170.

14. Ohkubo, T., Kanazawa, S., Nomoto, Y., Chang, J.S., Adachi, T., 1994. NOx removal by a pipe with nozzle-plate electrode corona discharge system. IEEE Trans. on Indus. Appli. 30, 856-861.

15. Ohkubo, T., Kanazawa, S., Nomoto, Y., Chang, J.S., Adachi, T., 1996. Time dependence of NOx removal rate by a corona radical shower system. IEEE Trans. on Indus. Appli. 32: 1058-1062.

16. Kanazawa, S., Chang, J.S., Round, G.F., Sheng, G., Ohkubo, T., 1997. Removal of NOx from flue gas by corona discharge activated methane radical shower. Journal of Electrostatics 40&41: 651-656.

17. Urashima, K., Chang, J.S., Park, J.Y., Lee, D.C., Chakrabarti, A., Ito, T., 1998. Reduction of NOx from natural gas combustion flue gas by corona discharge radical injection techniques. IEEE Trans. on Indus. Appli. 34: 934-939.

18. Hsunling B, Biswas P and Kenner T C. SO2 removal by NH3 gas injection: effects of temperature and moisture content [J]. Indus. & Engi. Chem. Research, 1994, 33(3): 1231-1236.

19. Dors M, Mizeraczyk J. NOx removal from a flue gas in a corona discharge-catalyst hybrid system. Catalysis Today, 2004, 89: 127-133.

20. Bhasavanich D, et al. Flue gas irradiation using pulsed corona and pulsed electron beam technology. J. of Electrostatics, 1999, 44:441-444.

21. Lowke J J, et al. Theoretical analysis of removal of oxides of sulphur and nitrogen in pulsed operation of electrostatic precipitators. IEEE Trans. on. Plasma Sci, 1995, 23(4): 661-671.

Some Technical Idea Evolutions Concerned with Electrostatic Precipitators in China 19

Some Technical Idea Evolutions Concerned with Electrostatic Precipitators in China

WANG Liqian1, FU Bohe2

(1 The Chinese Society of Electrostatic Precipitation Chindias Enviro & Energy Technologies, Ltd., Nanjing 210018, PR China E-mail: [email protected]

2 Shandong Shengjie Energy Environment Engineering Co., Ltd., Jinan 250014, PR China E-mial: [email protected])

Abstract: Electrostatic precipitator (ESP) was applied in China more than fifty years. There are many technical idea changes along with time or idea corrections from misunderstandings in this long run. A historical review of them will not only be interesting but also can draw some inspirations from them.

It is not possible to look back all the technical events. Only those have discussed thoroughly among Chinese ESP workers, such as: gas velocity in ESP, height of collecting electrodes, dust cleaning methods, selection of T/R and control modes, etc. are briefly described in this paper.

Two special topics, ESP for circulating fluid bed boiler and Orimulsion® combustion are also referred with. They are different kind of problems, but have drawn divergences between Chinese engineers. So, as an assortment, described here.

Keywords: ESP, gas velocity, field hight, rapping, energization control, T/R, CFB boiler, Orimulsion 1 GAS VELOCITY IN ESP, V

There have two ESP design golden rules in 1950’s. The one is the gas velocity in electric fields should not exceed 1m/sec. The other is the height of colleting electrode should not higher than 4.5 m.

The young ESP designers in China carefully obeyed these rules. But in viewing of the high cost of ESP, especially for a poor country like young new China, we always want to break the forbidden area after we have accumulated some experiences. Hence a lot of small and pilot ESP was tested in which V lied in the range of 1.5 m/sec–2.0 m/sec. In1957 one small pilot ESP [1] for collecting pyrite iron ore, velocity of 2 m/sec was selected, gave a collection efficiency of 98% or slight more which was satisfying at that time. In spite of this was the merely example, our mind was opened to accept V more than 1 m/sec.

But in industry scale, we never harvested successes above 1.5 m/sec. In a long run of about twenty years, 1.0–1.2 were mostly selected for industrial ESP.

Entered into 1980’s, China imported many fly ashes ESPs from western countries. Again, 98% to 99% efficiencies were designed which corresponding to about 200 mg/Nm3

–400 mg/Nm3 emissions. V of 1.2 m/sec to 1.4 m/sec was selected by the western ESP companies. We rejoiced that we have foreseen the “tendency” of increasing velocity of ESP.

But, soon afterwards we found, no matter what companies the ESP was imported from, high velocity was very often the main factor conducting failure in accordance with the emission the supplier guaranteed. Especially some top rapping ESPs, of which the design velocity was 1.4 m/sec. Their actual outlet dust concentration greatly went beyond of guaranteed values.

When China adopted the emission standard of 50 mg/Nm3 since 2004 (It comes later than developed countries several decades) and the power units became 300MW, 600 MW and 1000 MW, Chinese engineering became prudent to using velocity faster than 1 m/sec. They again fund V is the detrimental parameter in high performance ESP.

So, after almost of fifty years, thing go back to the original point. One meter per second again becomes a limit value. Of course, velocity is not the only factor dominating the ESP efficiency, and we can get the same efficiency by using different velocities, yet its importance no one can deny.

We are conscious of not that the velocity itself, but that more in essence, Reynolds number, is playing role. So, fast velocity / small ESP and low velocity/ big ESP, or in other words, a certain degree of turbulence is dominating for some efficiency. The multiple of velocity and hydraulic diameter of the ESP cross sectional area will be a critical parameter.

We remember that the so called FPA, the Fine Particulates Absorber, of which the idea was proposed by Feldman et al [2]. Its basic principle is to develop a laminar flow ESP. Since it is not possible to reduce gas velocity by a big margin, another way is reducing the gas channel width, which in FPA is only about 5 centimeter. So, low Reynolds number of less than 10000 was achieved. FPA can be designed to reach, as it principally said, any high efficiency except 100%, by pure hydraulic calculation because for laminar flow the efficiency can be mathematically predicated. Regret is that FPA is too expensive and pure laminar flow perhaps can never be gotten in big industrial equipments.

Once, about in the beginning of 1980’s, Professor Senich Masuda was taking lecture in Wuhan. Introducing about his Boxing Pre-charger, professor said field strength of 10 kV/cm in it was not difficult. There were not less than six to seven

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