ICESP XIII – Bangalore, India, 2013
The International Conference on Electrostatic Precipitation (ICESP) is the official conference of the International Society for Electrostatic Precipitation (ISESP). The following is a list of papers from the XIII ICESP Conference under their respective topic. Click on the title to view paper.
Session 1: ESP Design and Upgrade I:
Some observation regarding the matts ohnfeldt equation.
This paper presents three observations regarding the well-known Matts-Öhnfeldt formula for collection efficiency of electrostatic precipitators. The Matts-Öhnfeldt equation is universally used for ESP sizing and evaluation of ESP performance and relates the ESP collection efficiency to the (modified) migration velocity, wk, and the specific collecting area, A/Q, via h = 1 − exp[−(wkA/Q)k]. First it is pointed out that the Matts-Öhnfeldt equation is identical to the famous Weibull distribution function, which is used frequently in reliability theory and many other scientific areas. Second, it is shown that there exists a particle size distribution where, under the normal approximation of proportionality between particle diameter and migration velocity, the resulting ESP efficiency is exactly the Matts-Öhnfeldt formula. Finally, cases where the parameter k in the Matts-Öhnfeldt equation is larger than 1 are discussed and exemplified.
India has an ambitious power generation plan in the near future and continues to depend on coal as a fuel source (presently 58.5% of coal based power generation of the total installed capacity). Based on the high ash content of Indian coals, the electrostatic precipitator (ESP) is an important component of coal fired thermal power plants. With the progress of science and technology, the improvements in ESP are manifold. This paper highlights in the Indian scenario, an overview of electrostatic precipitators and the issues related to the design for structural integrity and performance of the electrostatic precipitator, issues related to improving performance efficiency and monitoring particulate emission.
Renovation and modernization of pollution control equipment to meet.
Electrical thermal power in India is produced mainly from fossil fuel fired boilers. During the initial phase of power development, coal with high calorific value and low ash content was available abundantly and emission was not a factor to be taken seriously. Over a period of time, quality of coal available for power plants got deteriorated. In addition, the emission has become very critical due to the fact that Central Pollution Control Board started issuing stricter norms. This has compelled the authorities to revisit the existing precipitators performance. The coal ash produced in thermal power plants are low sodium/potassium, low flue gas moisture with high inert content – all leading to high fly ash resistivity. Any attempt to improve the performance had to be looked into these factors as well. The extent of emission reduction required goes with number of years of boiler working, present operating condition and the pollution norms. This necessitated plant owners to go in for ESP renovation. In this paper, the authors describe the need for precipitator retrofit, approaches followed, various methods of renovation in Indian context and also made a case study as how the renovation of a precipitator installation in an Indian power plant (Plan X) was meticulously evolved and executed.
Results from esp-upgrades, including control systems.
Meeting new demands on particulate emissions from power plants and industrial processes in a cost effective way is important for the industry. Upgrading ESPs to higher performance levels include different measures. This paper presents result from such upgrades where the dominant part is the upgrade of power-supplies and control system.
Upgrading of the power supplies and control system so that the collection efficiency is optimized has, in many cases, proven to be a cost effective measure to reach new levels of emissions, stipulated by more stringent legislations. However, a successful ESP upgrade is dependent on more than just power supply and control system upgrades, various upgrade options are discussed in the present paper
Session 2: ESP Design and Upgrade II:
Review on the development of electrical precipitation industry in china.rev5.
This paper reviews the development environ- ment and business situation of the Electrical Precipitation Industry in China, 2011. A general technical progress of the industry, research and applications of the new technol- ogy are introduced. Prospects are made about the future development of the industry.
Electrostatic precipitator installed with ceramic foam on a collection plate.
An electrostatic precipitator (ESP) has been widely used for gas treatment such as flue gas cleaning and room air cleaning. Collection of particle matter (PM) in diesel exhaust is a new application of ESP. It shows very high collection efficiency for the PM in diesel exhaust, which includes fine particles ranging from some nanometer to some micrometer in diameter. Low pressure drop is another advantage of the ESP against conventional PM collection technologies like diesel particulate filter (DPF). However, PM slip due to abnormal reentrainment sometimes takes place because electric conductivity of the PM is high enough to lose charges on the collection plate.
In this study, to cope with this problem, porous ceramic foam consisting of many fine holes is used to suppress the reentrainment. The ceramic foam placed on a collecting plate of an ESP is expected to enhance capacity to keep the PM. It is also expected to reduce the velocity of the gas flow in the vicinity of the collection plate. Wire-plate type ESP was constructed and collection efficiency was measured and particle / gas flow in the ESP was measured.
As a result, ESP with the ceramic foam showed slightly higher diesel PM collection efficiency whereas discharge current was smaller than that of conventional ESP when the applied voltage and discharge gas were same. As a result of particle flow visualization in the ESP using carbon black fine particles to simulate diesel PM, smaller number of particles was observed when wet ceramic foam was used while both conventional ESP and ESP with dry ceramic foam resulted in similar particle density. The difference was more significant in the area downstream of the collection plate, where no electrostatic force acts on the particles. These results suggest that porous ceramic foam, especially when it is wet, effectively suppresses the reentrainment of the fine particles.
Emission reduction and availability improvement in old.
Industrial plants are one of the major users of Electrostatic Precipitators (ESPs) for particulate emission control. These are primarily Cement, Metallurgy, Pulp & Paper and Aluminium industries. The paper generally speaks about the challenges that we face with the old Industrial Precipitators to cope with stringent emission norms in spite of Physical dimensional and plant layout Restrictions. The Precipitators in such Industrial applications are used not only for emission control but also to recover the dust either to recycle or to use as end product.. Today’s technology has advanced, particularly in the area of High Voltage & Controls and shows extremely promising results beginning usually at 30 % emission reduction, but commonly much better than this . In this paper we specifically discuss about a Case Study on ESPs in a Gold Roaster application in Western Australia and compare the emission performance enhancement with few upgrades
Top electromagnetic impact rapping esp applied in 660mw units of a power plant in india.
This paper takes the mating top electromagnetic impact rapping ESPs for the 7 × 660MW supercritical boilers of some Indian power plant as an example to analyze the coal and ash characteristics and explain the ESP sizing consideration. The paper introduces the technical features of top electromagnetic impact rapping for collecting electrode (referred as CE hereinafter) & discharge electrode (referred as DE hereinafter), describes design problems of supersize ESP, such as CE & DE match model, thermal expansion problem, air flow uniform distribution and special design for hopper safety, energy conservation design, guarantee for low air leakage rate, etc. These give a conclusion of the design methods of supersize ESP for Indian coal-fired power plant and make a good reference for ESP design of other Indian coal fired power plants.
Session 3: ESP Performance Enhancement:
Enhancing quality of gas distribution tests in electrostatic precipitators_full_rev-3 0.
Air pollution control companies are continually working to develop new technologies to improve the performance and safety of their equipment. In this line, a new product has recently been developed to carry out automatic Gas Distribution (GD) tests in Electrostatic Precipitators (ESP) in a safe, convenient, cost effective and quick manner. The GD tests are done to ensure uniform gas distribution across ESP cross section (typical size: 15 m high x 12 m wide) which is critical for ESP‟s performance. Conventional method of GD test includes manual measurements (up to 400 points) of air velocities at various heights and widths across whole ESP cross-section. As generally the environment inside ESP is very dusty and without any proper arrangements to reach all measurement points, this method is unsafe, monotonous and tiring for inspector as well as expensive.
In this paper, the automatic gas distribution and measurement system with most advanced robotics and data transmission technologies is presented. The system consist of a compact robotic crawler to carry and position the velocity probes at desired positions in the ESP, the advanced wireless data capturing to display/store the measurement values in a PDA and a convenient application software for automatic data interpretation, analysis and report generation. The crawler automatically detects and maneuver obstacles if any. Automation of GD testing process eliminates the efforts of climbing up in ESP and taking the measurements and recording manually. In this way the new system increases the onsite-safety of operator, reduces his retention time in dusty environment, improves quality of data (by eliminating errors in measurements due to manual data capturing and enabling more nos. of measurements in less time) which, in the end, results in better performance of ESP and reduced emissions.
In this work the influence of electrode geometric arrangement on the operation of an circular electrostatic precipitator (ESP) was investigated using Particle Image Velocimetry (PIV) method. The ESP was a glass circular cylinder (29 mm in diameter, 300 mm long) equipped with a wire discharge electrode and circular-cylinder collecting electrode. The stainless-steel discharge wire electrode (0.23 mm in diameter, 100 mm long) was mounted either in the centre (concentric case) or off-centre of the cylinder (eccentric case), parallel to the cylinder axis. The circular-cylinder electrode was grounded. Positive voltage up to 10 kV was supplied to the wire-electrode through a 10 MΩ resistor. Air flow seeded with a cigarette smoke was blown axially along the ESP duct with an average velocity of 0.9 m/s. Also the case without forced axial flow was studied. The results showed that the eccentricity of the wire electrode with regard to the ESP axis is an important parameter influencing the operation of the circular ESP. Regardless of the discharge current intensity, a small shift of the wire electrode from the ESP axis (the eccentricity smaller than 8 %) did not change the discharge current intensity at constant operating voltage. However, when the eccentricity of the wire electrode exceeded 8 %, the discharge current intensity increased with increasing shift of the wire electrode from the ESP axis at constant operating voltage. But apart from that the discharge current flowing to that part of the collecting electrode which was nearer to the wire electrode was higher than that of the other part. The intensity of the discharge current to the closer part of collecting electrode increased with decreasing distance between the discharge electrode and the collecting electrode. The PIV measurements showed that eccentricity of the wire position influenced also the structure of the dust particle flow in the circular ESP. When the discharge wire was set almost ideally along the ESP cylinder axis, the dust particles moved radially towards the collecting circular-cylinder electrode. In contrast, an eccentricity in the wire position caused a severe disturbance in the radial movement of the particles, generating particle flow vortices. This can result in a lower collection efficiency of the dust particles in the ESP with eccentric wire electrode.
Monitoring of electrostatic fire and explosion hazards at the inlet to electrostatic precipitators.
The paper deals with the continuous monitoring of electrostatic fire and explosion hazards that can occur at the inlet to electrostatic precipitators (ESPs) when highly charged dust particles are transported by a gas carrier that can be the mixtures of both incombustible and combustible flue gases. The risk of ignition and even explosion is especially high in the presence of an explosive mixture of oxygen and, e.g., hydrocarbons, carbon monoxide, etc. To avoid the danger of electrostatic discharges and their consequences for a whole installation including an electrostatic precipitator a method and a specially designed and built system should effectively enable the continuous monitoring of the hazards and should immediately manage any automatic control system or some control elements. Some theoretical considerations concerning the method proposed, the physical quantities that must be measured, and the derivation of a novel dynamic safety criterion for assessing the risk of hazardous electrostatic discharges are presented. Finally, the author presents and discusses the possible practical application of the microprocessor-based measuring system verified experimentally in the past to the continuous monitoring of the hazards and to the management of an automatic control system to be put into operation.
Gaining control of esp fly ash hoppers.
Managing the fly ash inside ESP hoppers presents significant challenges. While avoiding the risk of pollution is extremely important, operation and maintenance costs must also be managed. The lack of decision support information is one of the reasons making this situation so hard. This paper will highlight the source of the problem, review available solutions with their strengths and shortcomings and then present a breakthrough development that offers a significant improvement for day to day management of these hoppers.
Session 4: Numerical Simulation:
The Electrostatic precipitator (ESP) is one of the important applications of static electric field used for abatement of pollution. Research is taken up at different dimensions (both simulation and experimental) involving study of V-I characteristics, effect of electrode configurations, load and ambient conditions on the working of ESP. In this paper, studies are made on an existing ESP at one of the industries. A simulation model is formulated to study the V-I characteristics of clean air and actual exhaust. Further, the characteristics are compared with the experimental results. It is observed that the simulated and experimental results match to a reasonable degree. Finally suggestions have been made to improve the performance of the existing ESP.
Strategy and criterion of gas distribution about efip.
Three key focuses about gas distribution of EFIP(Electrostatic Fabric Integrated Precipitator) is proposed .Mathematic relation between efficiency of electrostatic and uniformity of flow distribution is deduced. Upper limit of Sedimentation velocity is acquired with Stokes equation. Another relations between bags life and eroding velocity , costs and flow uniformity of outlet damper are also discussed.
The airflow distribution design of esp-ff hybrid dust collector at balco.
The airflow distribution of ESP-FF hybrid dust collector was researched completely in this paper. The airflow in the front electric field with a traditional airflow distribution form is non-uniform, which decreases the collection efficiency of ESP. Meanwhile, the airflow rising velocity in the back fabric filter chamber is increased, which decreases pulse cleaning efficiency else. A new airflow distribution developed by Zhejiang Feida Enviro., can make the airflow in the ESP area more uniform and the airflow rising velocity in the FF area slower, which can improve the performance of the ESP-FF hybrid dust collector. ESP-FF hybrid dust collector with this design has been applied at Balco power plant in India, which has been continuous operating from May, 2010. The dust emission is less than 4mg/Nm3.
The numerical simulation of different spacing coordinate double cylindrical vortex.
The coagulation technology of turbulence can improve the PM2.5 removal efficiency of ESP effectively, which is a hot technology researched by the scholars and manufacture. the turbulence produced by vortex column is the main power supply in the turbulence coagulation device, the velocity distribution, turbulence intensity, pressure loss and particles coagulation efficiency of different spacing L double vortex column was calculated in this paper, the results show that: The smaller of the spacing, the bigger of the turbulence and velocity effect between the two cylindrical; The value of pressure loss is biggest when L=0.4m, when the spacing L≥0.4m, the bigger of L, the smaller of the pressure loss; The particles coagulation efficiency of all operating condition are very obvious, the proportion of particle size which＜8μm decreases obviously, while the particle size which＜2μm is the most obvious; The coagulation efficiency of condition D is the best one, while the condition A is the worst.
In this article, numerical calculations of the gas distributions within the inlet nozzle of the electrostatic precipitator (ESP) are made by the methods of computational fluid dynamics (CFD). The inlet nozzle mesh divided by the Ansys Icem software is calculated by the CFX solver from the porous medium model. Simulation results show that gas distribution within the inlet nozzle is uneven without the guide plates and the root mean square (RSM) is very big which does not meet the requirement of the gas distribution uniformity. The gas distribution becomes clearly uniform after the guide plates are set. It is best to set eleven guide plates to the second and the third porous plates respectively and the value of the RSM could reach 0.203. The simulation results are verified by the experiments and agree with the experimental results which tells us that the CFD method is correct and viable.
Session 5: HV Power Supplies and Electrical Operation I:
Development of igbt based high voltage power supply for esp application.
This paper presents the development of Insulated Gate Bipolar Transistor (IGBT) based High Voltage (HV) power supply for Electro Static Precipitator (ESP) Application. With the fast switching power semiconductor devices like IGBT enable us to develop inverter based high voltage power supply for ESP application. Compared to conventional Silicon Controlled Rectifier (SCR) based technology the average corona power can be increased to improve the precipitator efficiency. In this development, Digital Signal Processor (DSP-TMS320F2810) has been used for PWM generation, protection, HMI interface and control algorithm implementation for ESP operation. The developed system is tested on the existing 50 Hz High Voltage Rectifier (HVR) unit with ESP load. The testing is performed at various frequencies ranging from 50Hz to 500 Hz for no-load, load and short-circuit condition. It is observed that the average DC voltage has increased with frequency and at the same time de-rating of the transformer is observed. During flashovers the fast current control of IGBT power inverters improves the precipitator performance due to fast voltage recovery resulting in further increase in corona power.
Use of 60hz trs at elevated frequencies final.
The objective of this paper is to provide a discussion of technical and commercial consideration that applies when choosing a Power Supply for Industrial Electrostatic Precipitators (ESP’s). The paper has focus on Switching power Supplies that operate at high frequencies and those that operate at mid-frequency. Issues addressed include power supply performance increase to realize as well as the cost and reliability that is associated with these technology choices. The paper is offered for the use by Electric Power Generating enterprises as well as other Industrial users of ESP’s.
The discussion of the critical issues of performance advantages, ease of installation, cost and reliability should provide valuable information for the selection process EPS power sources for new construction and even more so for replacement and upgrade/improvement projects.
ESP controls for plastic tube wet esp.
Evaluation of esp performance via__ its index value.
This paper discusses ESP performance via the so-called ESP index value. Particle emission, ESP sizing and power condition can be evaluated simultaneously. Based on our fine particle grade collection efficiency investigations, a cost-effective ESP can be designed when the index value for each field is around 200-260 (kV/cm)2m2/m3/s.
Session 6: HV Power Supplies and Electrical Operation II:
Use of three-phase rectifiers in esps for low resistivity.
This paper describes the use of three-phase HV transformer-rectifiers in low resistivity applications, as an alternative to switch mode power supplies (SMPS). The operation of these HV power supplies will be described showing the most important waveforms. Then the information that should be included in the rating plate for performing theoretical calculations will be reviewed. Afterwards the results obtained in a practical application will be presented. Finally some technical considerations regarding the firing of the thyristor controller will be given.
The three phase power supply system for low ripple high voltage in conventional technology.
Electrostatic precipitators are supplied with high voltage direct current systems. For many applications one of the main requirements is the quality of the high voltage insofar, that the ripple has to be very low. Low ripple means a very efficient voltage time area rate. At a standard single phase high voltage system with grid frequency the ripple is significantly high. With the technological more sophisticated high frequency power supplies the quality of the high voltage can be driven to a maximum. Another solution to get high quality for the high voltage with simple conventional technology is to use a three-phase current system. The three-phase high voltage power supply combines the advantages of the socalled conventional (single phase) current systems, e.g. simple and robust technology for an appropriate price, with the advantages of the switched mode power supply systems, mainly the low ripple at the high voltage side.
Three phase pf hv system for esp in a glass factory.
Electrical parameters of an operating industrial electrostatic.
The control systems of the electrical power supplies installed on coal power plants’ electrostatic precipitators (ESP) vary. However, their basic principle of operation is the same: the aim is to maintain the maximum current (or infrequently the maximum voltage) with a limited number of sparks and no spark-over.
This mode of control, by the number of sparks per minute (adjustable per field), is not suitable in the case of back-corona. If the ash resistivity is high, then intermittent energization has to be used. The simulation of performances of a dust collector operating under DC voltage is described extensively in the literature. This paper presents a simulation of the performances of an electrostatic precipitator powered by intermittent energization using physical models. For this reason, an equivalent electrical circuit of the electrostatic field is given, and the current-voltage characteristics are compared to those observed on an industrial site. Intermittent energization performances are then compared to those of a normal control mode.
Finally, data recorded on the dust collector of a coal-burning 250 MW unit using intermittent energization are analysed in order to detect process modification and faults in the electrostatic precipitator. This is carried out without having to stop the installation and without manual readings. Voltage current characteristics can be deduced from standard data collected continuously, thereby avoiding a specific system for acquiring data.
Session 7: HV Power Supplies and Electrical Operation III:
Energy optimization in electrostatic precipitators.
Electrostatic precipitators need electrical energy to separate the dust particles from the gas flow. The electrical energy causes the electrostatic field, which causes the Coulomb force inside the precipitator. The electrical current which flows through the electrostatic precipitator because of the electrical voltage over the ESP, is a secondary effect and can be helpful or disturbing for the precipitation rate. Depending on the conditions inside the electrostatic precipitator, there is always an optimum of the amount of electrical energy with reference to an optimum of precipitation rate. To optimize the precipitation rate of an electrostatic precipitator, there are certain technical measures to be implemented. The article describes the technical background for the electrical conditions in the electrostatic precipitator and gives solutions for the arising problems.
Emission reduction by optimization of electrical parameters.
Methods to ensure availability and operational flexibility.
Stringent emission norms for thermal power plants have resulted in need for better ESP performance which can be ensured only with well maintained ESP internals and a good control and monitoring system. ESP performance is affected by various boiler parameters and properties of the coal being used. For field wise control of the high voltage energisation and optimization, microprocessor based controllers are deployed. Similar controls are available separately or in-built with the field controller for rapping functions. For control and monitoring of the entire ESP parameters from a single point, PC based integrated control systems are used. The availability of such PC based systems becomes critical for the effective monitoring and maintenance of the ESP. Requirement is also felt for multiple PC based systems in different locations so as to be able to control and monitor the ESP parameters from multiple locations usually from ESP control room and boiler control room both, to ensure operational flexibility. Availability of the rapping system is another very critical factor as it is directly linked with the collection efficiency, especially for ash with high resistivity. This paper discusses approaches towards introduction of redundancy to rapping control and to the centralised monitoring and control systems to ensure their availability.
Soft core processor for electrostatic precipitator controller.
Reconfigurable processor architectures are increasingly becoming popular for many Industrial applications. Microprocessor obsolescence is the major concern for many companies. Reconfigurable logic can provide a feasible solution to this problem. By using soft core microprocessor embedded within a programmable logic device, we can own the processor core for use in any future devices for Industrial control application. This work presents soft-core processor design based on 8 bit microprocessor, address generator, decoder, ROM to house the firmware, RAM and Input/Outputs all on a single FPGA. The soft-core processor designed is more efficient in terms of processing speed by over 30 times over the prevailing 8 bit microprocessors. In this paper we have designed, developed and implemented architectures and novel algorithms for 8 bit processor using RTL complaint Verilog code. The system has been synthesized at 118 MHz using Xilinx target FPGA Vertex board and has a gate count of 85,000.The RTL design is truly platform and technology independent.
Session 8: Industrial Application:
Wet type electrostatic precipitator technology.
Due to the very high performance of Wet type Electrostatic Precipitator (WESP) in collecting particulate matters (PM), it is being widely used in various industrial applications, such as iron & steel plants and boiler plants. In this paper, well-established horizontal flow type WESP technology and newly developed vertical flow type WESP technology of Mitsubishi Heavy Industries Mechatronics Systems (MHI-MS) are introduced.
Comparison of wet and dry esp technologies.
With the recent surge in Electrostatic Precipitator (ESP) installations and future predictions of continued growth, ESP technology has been and will continue to be utilized for many applications. Wet and dry ESP technologies are in many ways similar but many questions arise as to the applicability of each technology as well as the advantages and limitations of each technology.
Siemens Environmental Systems & Services provides both wet and dry ESP technology for the utility power, cement and refinery industries as well as other applications. While wet and dry ESPs retain similar high voltage and collection systems and share similar physical characteristics, many differences exist; attributable mainly to the inherent design of the technology to address various size particles. Dry ESPs are used to capture coarse, filterable particulate matter (PM10) such as flyash. PM10 is defined by the U.S. Environmental Protection Agency (EPA) as particles smaller than 10 microns (a micron is one millionth of a meter). Wet ESPs capture sub-micron particulate matter, condensables and water mist commonly referred to as PM2.5 (defined by the EPA as particles less than 2.5 microns). Whereas dust or flyash characteristics play a large role in the sizing of dry ESPs, this is not the case with wet ESPs as they are not dependent upon particulate resistivity.
This paper compares the two technologies and Siemens’ experience with the technologies. To gain a better understanding of each technology a discussion of particle size is first required.
Dust resistivity measurements for industrial processes.
Wet esp for the collection of submicron particles, mist and air toxics.
New regulations are restricting particulate, acid gas and organic emissions to extremely low levels. Wet tubular electrostatic precipitators, with their ability to generate strong electrical fields in a wet, cooled atmosphere have demonstrated particulate emissions less than 0.0003 gr/dscf, with toxic organic, heavy metals and acid mist collection exceeding 99%. Designing parameters, field test data and operating data from installations on these processes are discussed in the paper.
Industrial particulate de-dusting plants, optimization in operating cost.
With respect to global discussions about climate change, efforts for reducing CO2 emissions and associated emission trading, it makes sense to bring into focus the power consumption of large facilities. It is particularly useful to take a closer look at air purification facilities. Conveyance of gaseous process and exhaust air flows, and the associated pressure loss in the de-dusting systems, causes the bigger part of electric energy consumption of industrial plants. Pressure loss reduction in filtration plants is a non-negligible factor for increasing energy efficiency. Combined with a suitable cleaning system and modern surface filtration media, energy requirement for de-dusting plants can be significantly reduced. The determination of filtration data by using standardized basic investigations and measurements in the field, gives the opportunity to characterize de-dusting plants in terms of energy and operating cost reduction. This applies to new and existing filter systems.
Especially for large gas volumes, bag filters has become indispensable in numerous industrial processes for separating particles from gas streams. They provide the benefit of meeting current and future emission limits in a single process step, even at highest raw gas dust content. In addition, the number of installations increases steadily for product recovery from exhaust air. The investment in modern jet-pulse bag filters will pay off after a short period for many applications due to the ability to recover valuable products contained in the exhaust air stream.
Session 9: Hybrid ESP and Fabric Filter Precipitation I:
Development of advanced electrostatic fabric filter.
Recently, countermeasures to reduce ambient fine particulate matters, especially with the diameters less than 2.5 micron meters (PM2.5), have been highly required, because of their negative influence to human health. One of the main sources of PM2.5 is coal-fired power station, and dust collector equipped there is one of the most important devices to reduce ambient PM2.5. In the coal-fired power station, electrostatic precipitator (hereinafter ESP) or fabric filter are usually applied, and fabric filter has an advantage in achieving stable and high performance regardless of kinds of coal since it is not affected by the property of coal ash, such as resistivity, while it has also a disadvantage in its high pressure loss which causes a problem of high power consumption. In order to reduce the pressure loss of fabric filter, hybrid dust collector combined with ESP and fabric filter or pre-charging system for fabric filter have already been proposed, but nevertheless they have not yet been so commonly used.
Authors have also addressed to develop a compact pre-charger, which can be installed in the duct at upstream of fabric filter to charge dust particles electrically there, for the purpose to economically reduce pressure loss of fabric filter, and during the process of the development, we have found that the effect of reducing pressure loss is affected much by property of the dust, and the deterioration of performance of reducing pressure loss is caused by back corona, just like the performance deterioration of ESP. Authors have succeeded in the development of pre-charger which can correspond to high resistivity dust which may cause back corona easily, through rich experience of countermeasures to back corona in ESP, and around 30 to 40 % reduction of the pressure loss, together with splendid and stable reduction of outlet emission, of fabric filter have been confirmed.
High ratio ffs with 12 m long bags for large coal fired power plants.
For many years, electrostatic precipitators (ESPs) have been used to collect particulate emissions from coal fired boilers. Today, with the need to produce the lowest cost electricity with the lowest possible emissions, coal fired boilers need to have flexibility to burn a wide variety of coals and at the same time achieve very low emissions. In this case the size, cost and arrangement of the ESP becomes very large and plants are now considering the use of high ratio fabric filters (HRFFs) to meet these requirements. While HRFFs have been used to collect particulate emissions from coal fired boilers for many years, designing the filters to meet the required emissions from large 800 to 1100 MWe boiler systems is a more challenging task than for smaller boilers (100 to 600 MWe).
The most effective means to reduce the steel weight and footprint of HRFFs is to increase the bag length, while maintaining, or even reducing, the bag-to-bag pitch. Alstom has more than 20 years experience of 8 m long bags, on-line cleaned, and more than 5 years successful experience of 10 m long on-line cleaned bags in coal fired boiler applications. Alstom Power has now developed a HRFF design with 12 m long bags, and reduced bag-to-bag pitch, for large coal fired boilers, as a continuation of the HRFF design with 10 m long bags successfully launched in 2008.
This paper presents information on key issues that need to be considered when designing and evaluating a HRFF with 12 m long bags for a large coal fired boiler installation. Aspects of gas/dust flow distribution to the individual compartments of the filter as well as the concerns regarding large flow/loading into the bag nest in each compartment will be discussed. A very efficient, newly developed, cleaning system has been incorporated in the filter to clean the bags properly without increasing dust emissions, and allowing the system pressure drop to be kept as low as possible.
Included is also information on several HRFF reference installations in the 800 – 1000 MWe boiler range, as well as data on coal fired boiler reference installations in Australia and South Africa with successful long-term operation on abrasive fly ash at inlet loads similar to those from firing domestic Indian coals.
The reduction in HRFF first cost with 12 m as compared to 10 m long bags, and tighter bag row pitch, is estimated at around 10 %.
Bag filter retrofit option for indian utilities_challenges and solutions.
Solid particulate emission (SPM) control is the key today to start new coal fired utility project as well as to run older coal based power plants. Considering prevailing economics, the existing plants want to extend their life and hence to retrofit the emission control equipment. There are two major options of retrofit to mitigate SPM i.e. Electro Static Precipitator (ESP) and bag filter (BF). Such retrofits are not new for worldwide older plants as well in India. There are more number of methods available to carry out ESP retrofit and almost all methods got executed and fructified over last two decades in India at various plants. But the number of Bag Filter retrofit is very few. Both options have their own merits and de-merits. Even though retrofit of bag filter for older coal fired plants require less floor space than required for ESP, it has more challenges with regard to boiler operation and maintenance. Bag filter can be a better choice for finer particle collection and for lower emission levels. However it is sensitive to boiler operation particularly with regard to oil firing and higher flue gas temperature. Aged boilers with older technology of fuel firing have more problems & challenges to be addressed to go in for bag filter retrofit.
The paper brings out salient points to be taken care during bag filter retrofit. This will be very much useful to power plant owners when they specify system design requirements for bag filter retrofit.
Evaluation of ff pulse cleaning valves.
Three FF cleaning valves were compared with the reference valves “D” and “E” by measurement of bag pulse pressure. In addition to this, an indicative life time test was performed to study the durability and type of failure for the valves. Test results regarding pulse pressure and longtime durability are presented. A comparison is made between existing membrane valves on the market, model “A”, “B” and “C” and the reference valves “D” and “E”, both of piston type.
Session 10: Hybrid ESP and Fabric Filter Precipitation II:
The application of esp-ff hybrid dust collector in india coal-fired power plant 600mw unit.
There have been already several sets of ESP-FF hybrid dust collector for 600MW units provided by Zhejiang Feida Environmental Science & Technology Co. Ltd. (hereafter short as FEIDA) being operated in India. This paper introduced the structure style of ESP-FF hybrid dust collector, and concluded that it’s relatively suitable to apply the separated type in India for the special electric power industry. And the ESP-FF hybrid dust collector is a correct selection with the enhancing of outlet emission standard. In India, the FEIDA ESP-FF hybrid dust collector is still in good operating condition.
Fractional bypass of raw gas to improve performance of.
In this paper it is suggested that the performance of a hybrid ESP-FF system can be improved by utilizing a small controlled flue gas bypass stream to transport virgin fly ash from the ESP inlet to the fabric filter inlet. The purpose of this bypass stream, which may be in the order of 5-10% of the total flue gas flow, is to produce a particle size distribution at the fabric filter inlet that is quasi-similar to the original distribution leaving the furnace. This would avoid potential problems with e.g. bag blinding, resulting from the very fine particles escaping the ESP. Since the bypass flow is low compared to the total gas flow the resulting particle concentration is still much lower than the concentration at the boiler exit, allowing higher filtration velocity and lower pulse cleaning frequency in the fabric filter. The bypass stream flow can be adjusted until optimum performance is achieved, and may of course also be completely turned off in extreme cases, such as during bag failure in the FF.
Hybrid system to enhance particulate collection efficiency in coal based thermal power plants.
An integrated hybrid system consisting of an ESP topped by mechanical collector and bottomed by fabric filter has been proposed. It is shown that such system has got better collection efficiency, lesser collection area compared to equivalent ESP alone system
Experimental research on efip technology.
In April 2005, the first EFIP system developed by our company is successfully put into operation on Chinese 50MW coal-fired power plant, and since then, after continuous improvement and promotion, this technology is rapidly becoming one of the major dust removal technologies which meets 30mg/Nm3 even below 20mg/Nm3 emission standard for China coal-fired power plant and widely used in 300-1000MW power plants. In the application process of EFIP system, this innovative technology is increasingly matured by experiment research combined with (based on) the engineering practice and continuous technological innovation. With the global environmental protection requirements continue to increase, the EFIP dust removal technology is moving towards to the new direction of technology development of efficient removal of PM2.5, synergy removing mercury metal and its compounds and other multi-pollutant co-processing.
Session 11: Flue Gas Conditioning:
Experimental studies on wfgd sewage injection upstream of electrostatic precipitator.
Experimental study on impact of ammonia dosing on the resistivity of fly ash.
Performance of Electrostatic precipitators (ESP) depends on the characteristics of the coal used and the fly ash generated. Fly ash resistivity is one of the vital parameters which significantly influence the performance and hence the sizing of ESP. Indian coal is generally characterized with high ash content and high ash resistivity. High resistivity of fly ash results in reduced ESP efficiency and thus forces for an over sized ESP. So it is of prime importance to reduce the ash resistivity to enhance ESP efficiency. Also, knowledge of ash resistivity is required at design stage for sizing of the ESP. In this paper we are discussing our experimental study on ash resistivity measurement, influence of ammonia conditioning on ash resistivity and optimum ammonia conditioning using resistivity measuring equipment with ash samples collected from various Indian power plants.
The development & application of lsc heat recovery esp.
This article is mainly about the development background, principle and key points of Low Temperature Coal Saving heat recovery Electrostatic Precipitator (hereinafter referred to as ESP), focusing on its development & application on Yuejia Power 135MW circulating fluid bed coal-fired boiler and summarizing for further market expansion.
Application of the lower temperature electrostatic precipitator.
On the prerequisite of energy-saving and heat recovery, lower temperature electrostatic precipitator technique can achieve a very high collecting efficiency. Compared with other dust removal technologies, the paper analyzes the principle, performance and energy-saving effect of the lower temperature electrostatic precipitator technology.
Session 12: Flue Gas Conditioning:
Computational modeling of electrohydrodynamically-influenced mercury adsorption within esps.
Powdered activated carbon (PAC) injection into the flue gas at a location upstream of an electrostatic precipitator (ESP) has emerged as a leading technology capable of reaching the ~90% reduction in mercury emissions representing the performance target set by the U.S. EPA’s new Mercury and Air Toxics Standard (MATS). The present study presents a newly developed 2-D numerical model of electrohydrodynamically-influenced trace gas adsorption within a simulated section of a wire plate ESP. The results reveal fundamental details of the gas-particle dynamics and mass transfer enhancements that, along with powdered mercury sorbents and their chemical treatments, can enable efficient mercury adsorption within ESPs.
Development of single-stage, small-size electrostatic precipitator for high gas-velocity with.
In this study, we had developed single-stage, small-size Electrostatic Precipitator(ESP) for high velocity(6~12 m/s) with slit-type collection electorde(CE). Slit-type CE is the SUS plate holed long slit, perpendicular direction of airflow. Through experiments of 4 cases, slit-width CE(0, 5, 10, 20 mm), we had confirmed that slit-type ESP efficiency is higher than original ESP(0 mm slit) in the condition of high velocity conditions(over 6 m/s). Developed slit-type ESP could be utilized for air cleaning system in the subway-tunnel or road-tunnel.
Electrostatic precipitator performance in old boilers in India cause & suggested remedial measures.
Session 13: Gaseous Discharges & Nonthermal Plasma Applications:
Total emission control for multi-fuel boiler system with.
A plant of low emission hot water or steam supplying system which consisted of a multi-fuel boiler (gas or oil fuel) and a plasma-chemical hybrid NOx removal was demonstrated. The boiler had a steam generation rate of 2.5 t/h. Many experiments were conducted using fuel gas and oils, and the flue gas flow rate was from 550 to 2250 Nm3/h. Operational characteristics were investigated in order to achieve stable continuous operation. Ozone injection for NO oxidation and Na2SO3 solution for NO2 reduction were essential factors for the NOx removal system. Operational indexes were obtained, such as O3 injection method, Na2SO3 supply rate, and the flow rate correlation among Na2SO3 supply, drainage, and fresh water.
Study of particulate matter removal mechanism by using non-thermal plasma technology.
Numbers of diesel engines in both stationary and mobile applications are increasing nowadays. Diesel engines emit lower Hydrocarbon (HC) and Carbon monoxide (CO) than gasoline engines. However, they can produce more nitrogen oxides (NOx) and have higher particulate matter (PM). On the other hand, emissions standards are getting stringent day by day due to considerable concerns about unregulated pollutants and particularly ultrafine particles deleterious effect on human health. Non-thermal plasma (NTP) treatment of exhaust gas is known as a promising technology for both NOx and PM reduction by introducing plasma inside the exhaust gas. Vehicle exhaust gases undergo chemical changes when exposed to plasma. In this study, the PM removal mechanism using NTP by applying high voltage pulses of up to 20 kVpp with a repetition rate of 10 kHz are investigated. It is found that, voltage increase not necessarily has a positive effect on PM removal in diesel engine emissions.
Optimisation of gas ehd pump with nozzle down stream.
With the application of high voltage between sharply curved electrode and blunt electrode, the air near sharply curved electrode ionizes. The ions formed are accelerated towards blunt electrode due to electric field. In the process they collide with electrically neutral molecules and transfer their momentum completely as the collision is assumed to be elastic. This results in motion of air which is called ionic wind or corona wind or Electrohydrodynamic wind. Electrohydrodynamics (EHD) refers to the study of this interaction of fluid motion and electric field.
Research on the airflow distribution in the fabric area of efp.
Numerical simulation method was used to calculate the airflow distribution in the fabric area. We established the 3-D structure for Electrostatic Fabric Precipitator(EFP) of 600MW unit by the Pro/Engineering software and dealt with the data collecting from the simulation with the Tecplot 360. Data about airflow distribution in the filter area were obtained by comparing different operation conditions. In the filter area, the biggest pressure is 530Pa and the speed in the bags was changing from 1m/s to 4m/s. Bags located at the front of fabric area are tend to be damaged due to the fast flue gas and those bags in the second filter area would be used for more time because of the smaller flux than the first one. The numerical simulation results are reasonable and could be used as the reference to the designing of Electrostatic Fabric Precipitator.
