ANSWERS TO IMPORTANT POWER PLANT QUESTIONS OF THE MONTH
Here is a copy of our “Power Plant Questions of the Month”. We propose to email it to you each month for the next year free of charge. We believe if we can demonstrate the value of our information you will want to know more about our Power Plant Knowledge system. We think that one of these months you will find one of these subjects to be important enough to want to explore it in depth and then we can make our sales pitch.
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POWER PLANT QUESTIONS OF THE MONTH
WILL POWER PLANTS HAVE PROBLEMS MEETING THE 2003 NOx REDUCTION REQUIREMENTS?
The answer is maybe. The bigger utilities with a number of affected plants are faced with only a few outages over the next three years. AEP and TVA have lined up partners in order to nail down the availability of engineering and equipment. But some of the mechanical contractors are already reporting full shops and a heavy workload. The secret is going to be maximum effort now to finalize plans and line up contractors. Those utilities who wait until 2001 are going to be out of luck.
WHAT KIND OF OPERATIONAL PROBLEMS COULD I HAVE WITH NOx CONTROLS?
Combustion modifications can result in accelerated tube wastage and unburned carbon in the fly ash. SCR problems include arsenic poisoning of the catalyst and ammonia slip. In fact, California and Massachusetts are toying with regulations to require zero ammonia emissions. But even absent regulations ammonia can cause problems. It can plug up your air heater and it can contaminate your fly ash. Buyers will definitely react negatively to ammonia contaminated fly ash? Some of the vendors say their methods of ammonia distribution and control eliminate this problem. Others say the answer is a staged system.
We are not going to devote too much attention to NOx issues in this Overview because we have a NOx Chat Room with detailed discussions of all these issues. It is free and easily accessible on our web site.
To go to the NOx Chat Room click here: http://www.mcilvainecompany.com/discuss.
IS THE AVERAGE UTILITY OVER REPORTING NOx AND SOx?
Many utilities are actually emitting less NOx and SOx than they are reporting. Flows are actually 5% lower than instruments are indicating. This could be worth $ millions per year to the medium size utility.
DO I HAVE TO CHANGE CEMS DUE TO PART 75 AMENDMENT?
EPA has amended sections of Part 75 to provide more accurate measurement of NOx mass emissions. The question is whether to upgrade from an emission rate monitoring system to a mass monitoring system or whether it is better to replace the system and start over. Newer analyzers do not confuse NO with total NOx . Keep in mind that the value of accuracy goes up substantially with the trading of NOx at $3,000/ton.
CAN YOU MEASURE MERCURY CONTINUOUSLY AND ACCURATELY ?
It appears that continuous emission monitors for mercury will be able to duplicate the wet chemistry methods within 20%. Don’t be surprised if within a few years both continuous mercury and mass particulate monitors are required for each power plant stack. Tests of mass particulate monitors on incinerators have been positive. A number of power plants in Europe are already using mass particulate monitors of the tape sampler type.
ARE PRECIPITATOR PARTICLE EMISSIONS PRECURSORS OF PM2.5?
One of the problems in quantifying PM2.5 emissions is going to be semantics. How is a large agglomerate of small particles which is emitted when rapping the precipitator classified? If it quickly disintegrates when it loses its electrical charge, isn’t it all small particles?
How important advances in IT instrumentation, controls, automation, monitoring and process optimization are changing the very nature of electric power generation. Jason Makansi advises that the individual information technology functions must be integrated into a cohesive system that communicates seamlessly with IT networks external to the plant. The ultimate goal is economic optimization.
IT changes and is integrated into the personnel organization and cultures-minimizing people, making work safer, focusing on results, moving towards predictive maintenance, pushing the envelope on operations and performance, breaking down barriers between departments (i.e. maintenance and operations). It will create “virtual plant staffs, crews and teams” responsible for multiple plants and will facilitate third-party service contracts. A 1400 MW coal-fired plant in Australia is supervised by two people on site during the second and third shifts. This will become commonplace in the future.
SHOULD YOU REPLACE PRECIPITATOR INTERNALS WITH BAGS?
The replacement of precipitator internals with bags at the State Line plant is a significant event. While other bidders were following the specs with bids on precipitator internals, Wheelabrator bid a conversion to a baghouse. The flexibility to burn a greater variety of fuels led Southern to select the baghouse conversion. This decision was followed by the Sheldon station award to ABB to replace the existing precipitators with fabric filters.
DO YOU HAVE TO WORRY ABOUT TITLE V AND THE TOTAL PARTICULATE EMMISSIONS?
The problem is that your present opacity monitor doesn’t tell you how much particulate is emitted during excursions. So it is going to be difficult to verify total mass emissions. Unfortunately your Title V permit probably limits you to a specific tons per year of particulate. But there are some simple steps to take to protect yourself. One is to do some stack testing during upset or start up and shut down conditions. If the emissions are only slightly higher than normal then you have some supporting evidence.
IS THERE A ROLE FOR WASTE BURNING IN MY PLANT?
While coal gasification is still a questionable option from a cost standpoint, the gasification of waste can be quite attractive. In parts of Europe power plants are forced to burn 10% biomass in each coal-fired boiler. Gasifying waste and using it as a reburn fuel provides both the economic benefits plus the reduction of NOx. But just simple fuel blending is in vogue. Connectiv is fueling one plant with chicken manure. Illinois Power will burn all the plastic pellets it can find.
WHEN IF EVER IS COFIRING GAS ATTRACTIVE?
The answer is that there are many situations that favor cofiring. In the ozone season it is a way to reduce NOx. During low load conditions the use of gas may be more economic than running the pulverizers and burning the lower cost coal. Most importantly you have a back up if your air pollution control or coal handling equipment fails at a time of high demand. Mississippi Power found that they could burn a combination of petroleum coke and natural gas more inexpensively than coal.
WHAT’S NEW IN GAS TURBINE COMBINED CYCLE SYSTEM COMPONENTS?
There is probably more new and useful technology being developed to improve the complete combined cycle system than there is in the turbines themselves. This is a pretty expansive claim since the new series of turbines has substantially higher output and efficiency. But a substantial part of the output and cost is found in the other components. New ways to cool and purify the intake air can substantially improve output and lower life cycle costs. As they say the devil is in the details. The disc centrifuge manufacturers have MADE improvements in fuel purification. The cooling tower people have more efficient packings.
There is even a better access door you should consider rather than let each component supplier furnish a hard-to-open home grown design.
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