“Dry Sorbents and Systems and Material Handling in Coal-fired Power Plants” is the
“Hot Topic Hour” on June 7 and June 21, 2012
Because we have had so much interest in this subject, we scheduled two sessions in order to keep the Hot Topic Hour within 90 minutes and to accommodate all of the persons who desired to make a presentation. All persons that register for the first session on June 7th will automatically be registered for the second session on June 21st at no additional cost.
Dry Sorbent Injection (DSI) is a process in which a powdered sorbent material such as Trona (sodium sesquicarbonate, a naturally occurring mineral mined in Wyoming), sodium bicarbonate, hydrated lime or activated carbon is injected into the flue gas from fossil-fueled boilers to control acid gases, such as sulfur dioxide (SO2), hydrogen chloride (HCl), sulfuric acid (H2SO4) and more recently mercury (Hg). Although DSI has been used for more than twenty years, now that the U.S. EPA has finalized the MATS rule establishing low limits on Hg, HCl and filterable particulate matter (fPM) emissions for all U.S. coal- and oil-fired power plants greater than 25 MW, DSI is gaining even greater attention.
DSI advantages include lower equipment costs (first cost) as well as decreases in operations and maintenance costs and a lower life cycle cost than other pollution control technologies. DSI can be an effective, low cost, multi-pollutant control solution that can help plants meet or even exceed their MATS and CSAPR emission limits. DSI is a viable alternative for units in which the investment for wet or dry flue gas desulfurization (FGD) cannot be justified and for power plants that just need to improve the performance of existing pollution control equipment.
However, DSI is not as simple as it may appear. The relationship between various acid gases and other controlled gases in the flue gas can be very complex. DSI can also have an impact on the performance of other existing control equipment and vice-versa. Careful study is necessary to select the sorbent and sorbent particle size that will achieve control goals at the lowest operating cost. Study is also necessary to determine how the sorbent will affect or be affected by other emission control equipment installed.
Selection of the correct delivery system components is also critical. Dry materials can solidify and plug critical conveying tubes and injection devices. And to obtain the lowest sorbent usage (and usually cost), the sorbent particle size needs to be appropriate to the flue gas conditions and the sorbent needs to be uniformly delivered to the gas stream.
The speakers listed below will address the issues related to sorbent selection (which sorbent, which particle size and when it is cost effective and appropriate to use and when it is not) and the design, installation, operation and maintenance of DSI systems for various applications, provide suggestions for reducing acquisition, installation, operation and maintenance costs while improving efficiency and update us on new technology or designs under development to improve the performance and reliability of DSI systems. They may also compare DSI system costs and performance to other control technologies that could be used.
Note: Speakers are listed for each day alphabetically by company and not necessarily in the order in which they will be presenting
Speakers on Thursday June 7, 2012 at 10 a.m. (Central time) will be:
Chetan Chothani, CEO Breen Energy Solutions, will present “Dry Sorbent Injection and Gas Co-Fire / FLGR for Small to Medium Plants.” Small to medium size coal-fired power plants without SCRs and scrubbers face a difficult choice in meeting MATS and CSAPR regulations, particularly with natural gas prices hovering at record lows. This unique combination of technologies provides these plants with an alternative to stay economically viable while meeting regulations and it makes DSI relevant as part of a combined technology solution. Gas co-fire provides fuel flexibility, FLGR (Fuel Lean Gas Reburn) provides NOx reduction and DSI provides SO2 and SO3 mitigation while keeping overall dust loading constant on the ESP.
David Escott, Power Market Manager at FLSmidth, Inc, will present “Dry Sorbent Injection – Ten Years After.” The year was 2002. It was the beginning of the first wave of DSI. The goal was to eliminate SO3 and the blue plume associated with the combination of high sulfur coal, SCR and wet scrubbers. FLSmidth had been developing and optimizing its metering and delivery systems for a few sorbents to help remove the plume.
Flash forward to the year 2012 … It is less about the “stack-up” or the equipment under the silo, and more about the optimization of the acid gas removal process. It is no longer just SO3; we have the MATS rule addressing HCl and Hg; we may have CSAPR and regional decrees for SO2, and we still have SO3, though it is mitigated more for improved mercury removal. We need to validate that DSI is the correct technology: there are a greater number of proven technologies including dry FGD that have closed the gap in capital and operating cost differences between DSI and FGD. We need to match the sorbent to the application. In 2002 it was simply a matter of cost, availability and ESP performance. Now we must consider sorbent affinity for HCl and HF vs. SO2 – and the final sorbent selection may depend upon how much of each must be removed.
Finally, largely due to MATS, the APC device has a greater influence on the system design. There is a larger emphasis on fabric filters to achieve PM targets. A filter can serve to improve sorbent efficiency through enhanced capture in filter cakes, and in fact, fabric filters can be designed to improve the development of the filter cake. Reduced sorbent consumption minimizes the cost difference among sorbents and stand alone “polishing” filters allow scalped ash to be kept separate from scrubber / injection byproducts.
In this presentation we will investigate the decisions and evaluations that help steer our customers towards today’s DSI system, which might include ultra-fine milled sorbent injection with activated carbon injection and a fabric filter.
Blaz Jurko, Gebr. Pfeiffer, Inc, (GP), will discuss technology for dry sorbent material preparation / grinding.
· Limestone grinding
· Lime hydration
· Gypsum grinding / calcining
· Dry sorbent product fineness
· Precise material separation / classification
The emphasis of the presentation will be on their experience in dry grinding and material preparation and ability of this technology to closely match the dry sorbent injection process requirements. GP can offer many options on the precise material fineness in order to follow the process specifications.
Marcus (Marc) Sylvester, Vice President of Sales for Midwest Energy Emissions Corporation, will discuss their patented “Sorbent Enhancement Additives” technology for mercury control and handling concerns with the most recent commercial installation. Midwest Energy Emissions Corporation (ME2C) is a global company with a focus on mercury capture programs, utilizing patented technologies to control mercury emissions from major utility and industrial boilers. ME2C has worked closely with the Energy & Environmental Research Center (EERC) of the University of North Dakota to develop and deploy the best performing and most cost effective mercury control technologies in the world. ME2C’s mercury reduction program is designed to achieve greater than 90 percent capture at less than one-half the cost of brominated activated carbon.
Lew Benson, SO2 Group Leader at Nalco/Mobotec, will discuss modeling of dry sorbent injection including CFD and chemical reaction modeling.
Speakers on Thursday, June 21, 2012 at 10 a.m. (Central time) will be:
Tony Licata, Vice President of Babcock Power Environmental, Inc, will discuss the “Impact of Mixing on Performance of Dry Sorbent Injection (DSI) /Activated Carbon Systems.” Most people in the industry expect that DSI will play a significant role in the planning and implementation strategies for air quality compliance in the next few years. To date most of the published papers and technology interest has centered on which sorbent to use -- lime or sodium and types of injection equipment. There has been little interest in the optimization of mass transfer. Optimization of sorbent utilization may impact the viability of DSI on many projects. This presentation will discuss methods of enhancing mass transfer and the impacts of poor gas/sorbent mixing.
Mike Tate, Technical Manager of Research & Development for Graymont, Inc, will address the following questions: What are the key properties of hydrated lime that impact sorbent performance? How can these properties affect the design of sorbent injection systems? His presentation will describe lime characteristics and how they should be considered in the design of lime handling and storage systems.
Curt Biehn, Manager of Technical Sales & Marketing at Mississippi Lime, will present “Meeting Regulatory Needs with Hydrated Lime DSI.” The presentation will highlight hydrated lime's performance for SO3 mitigation in a variety of scenarios. Examples of full-scale applications that used hydrated lime to meet 2015 MATS guidelines will be provided. Comments on hydrated lime's flexibility towards injection location optimization will also be presented.
Yougen Kong, P.E., Ph.D., Technical Development Manager at Solvay Chemicals, Inc, will present “Dry Injection of Sodium Sorbents for HCl and SO2 Mitigation - Effects of Using Mills.” The presentation will describe the technologies of milling trona and sodium bicarbonate, pros and cons of each technology, capital and maintenance costs of mill systems and good system design principles. The dry injection of sodium bicarbonate or trona is a low-cost solution and has shown over 99 percent removal of HCl and 95 percent removal of SO2. The trona shipped out of production has a mean diameter of about 30 µm and can be used as is. On the other hand, the sodium bicarbonate has a mean diameter of about 150 µm and needs to be milled before being injected into the flue gas. While it is optional to mill trona, milling trona can reduce the particle sizes and thus improve the dispersion of trona particles inside the flue gas. Better mixing between the particles and flue gas, in combination with higher surface areas of finer trona particles, can result in better mitigation performance of HCl and SO2. Since sodium bicarbonate out of production is too coarse to be injected directly into the flue gas, it needs to be milled in order to have good mitigation performance of HCl and SO2.
Steve Baloga, P.E., Southern Air Solutions Corporation, will present “Dry Reagent Injection for Utility MATS, ICI Boiler and Portland Cement Kiln NESHAP Compliance.” Since Steve does not represent trona or DSI equipment providers, he will give an unbiased assessment of trona for DSI and associated issues based on experience gained over many trials. Results of trona injection for SO2 and HCl reduction for a utility boiler with ESP, an industrial boiler with ESP and a cement kiln with FFBH will be presented. The effect of particle size reduction for trona will be discussed. In the course of the presentation, additional considerations will be mentioned that users must consider when evaluating sodium based reagents: impact on PM emissions (including PM2.5/CPM), impact to Hg emissions, impact to flyash quality, flue gas temperature limitations, material handling considerations (avoiding pre-calcination), removal and potential leaching of volatile HAP metals in trona laden flyash and cement alkali silica reactivity issues related to sodium sorbents.
To register for the Hot Topic Hour on June 7 and June 21, 2012 at 10 a.m. (Central time) click on: http://www.mcilvainecompany.com/brochures/hot_topic_hour_registration.htm.