Improving ESP Performance is Hot Topic Hour on Jan. 28, 2010 at 10 a.m.
EPA is under a legal deadline to develop a first-time maximum achievable control technology (MACT) standard for coal- and oil-fired power plants by 2011. As part of the MACT, EPA intends to set an emission standard for particulates as well as every other HAP emitted. Since it is probable that particulate emissions will become a surrogate for HAPS, control of PM2.5 emissions will be even more critical. Because of this, it is almost a certainty that operators of coal-fired power plants, not just power plants located in PM2.5 NAAQS non-attainment areas but all power plants, will need to reduce particulate emissions to levels well below current standards.
While there are several options for controlling particulate emissions, the primary method in use at coal-fired power plants today to remove particulates from the stack gas is through the use of electrostatic precipitators. The ESP represents a significant investment by the utility and if they need to also install a baghouse because the ESP cannot economically meet the new regulations this will be a large additional expense. Part of the problem is that existing precipitators were designed to provide a particular efficiency of collection for the coals being used or intended to be used at the time of the ESP was designed.
As utilities have switched to low sulfur coal to meet environmental regulations for SO2 emissions, the particulate control problem has only become more difficult. But over the past ten years development of better power supplies especially High Frequency Switched Mode Power Supplies (HFSMPS), improvements to the mechanical design and modeling of air flow to improve gas velocity and velocity distribution as well as flue gas conditioning now offer the possibility to significantly reduce these operating costs and greatly increase the removal of fine particulates and other pollutants.
Over the past years, companies that supply precipitators and their key components as well as companies that provide services to maintain and tune up precipitators have developed methods and equipment to fine tune precipitators to both improve the performance and to reduce the power required to achieve this performance. In some situations, an electrostatic precipitator can even approach the performance of fabric filters in removing fine particulates and eliminate the need for a baghouse to meet regulatory requirements for particulates. It has even been suggested that a modern properly designed ESP may offer a better way to control mercury emissions and make a baghouse unnecessary.
The following speakers will address the issues facing the utility industry regarding the control of particulates using ESPs, the new technologies that have been or are being developed to improve the performance of older and new ESPs and the performance of newly designed and installed ESPs as well as newly upgraded or retrofitted units.
Yougen Kong, P.E., Ph.D., Technical Development Manager at Solvay Chemicals, Inc. will describe a better alternative to SO3 for conditioning electrostatic precipitators. Using SO3 to condition the flue gas of boilers burning low-sulfur coal is going to face a new challenge: Mercury control, since SO3 inhibits the mercury removal by either fly ash or powdered activated carbon (PAC). A better alternative is to inject trona into flue gas upstream of a hot-side or cold-side ESP. It can lower the resistivity of fly ash and solve the problem of back corona due to “sodium depletion” of hot-side ESPs. In addition, the added trona can remove SO3 and thus improve the mercury removal. The trona addition system is simple and its capital cost is much lower than that of an SO3 production and injection system.
Tapan Mukherjee, Director of Business Development and Harry Wheeler Environmental Services Operation of Alstom Power will discuss how the performance of existing ESPs can be enhanced by utilizing multiple techniques. PM removal efficiency within the confines of a box can improve by changing electrode geometry (plate spacing), internals like discharge electrodes, rapping system as well as by replacing conventional T/R sets with high frequency power supplies and advanced controllers. Although fabric filters are more widely used in green field plants as the PM collector with activated carbon systems for mercury control, proven technology is now available to achieve a high rate of mercury removal keeping the existing ESP as PM collector.
Paul Leanza, Senior Technical Engineer for Post Combustion Control Equipment at Pollution Control Services, Inc. will focus on evaluating existing precipitator’s ability to achieve the future PM2.5 regulations. The majority of existing ESPs are not operating under their original design basis. Many existing ESPs have not been upgraded with modern operating philosophies or equipment. Taking a holistic approach in evaluating the precipitator in its current operating parameters permits a viable plan forward as the operating parameters have been modified as additional post combustion control equipment like SO2, SO3, NOx, and Hg control have been incorporated over the last 15 years.
Helmut Herder, Vice-President, Environmental Technology Division of NWL will describe how and why use of the Power Plus SMPS will improve the collection efficiency of an ESP while using less power (KVA input) and give examples of the performance results using PowerPlus.
Jonathan (Jon) Barr, Vice-President, Sales & Marketing, ADA-ES (ADA Environmental Solutions LLC). Some coal plants use SO3 to improve the performance of their ESPs with PRB coal. If these plants are required to control mercury emissions and use activated carbon, the SO3 can reduce the carbon's effectiveness and reduce the efficiency of the mercury removal. ADA has a patented flue gas conditioning chemical that is an effective SO3 replacement and does not interfere with activated carbon's ability to adsorb mercury.
To register for the “Hot Topic Hour” on January 28, 2010 at 10 a.m. CDT (Chicago time), click on: http://www.mcilvainecompany.com/brochures/FGDnetoppbroch/Default1.htm.
Bob McIlvaine
President
847 784 0012 ext 112
rmcilvaine@mcilvainecompany.com