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What's New: Our Latest Installation is featured under "Flame Impingement".Utility Power Boilers
 Acoustic
Pyrometry affords the boiler operator and design engineer a
new information source about the heat transfer potential of
the combustion gases in the furnace enclosure and super heater
tube banks. The real-time and continuous gas temperature measurement
in areas hostile or unavailable to other sensors, provides valuable
data to affect control adjustments impacting combustion effect,
emissions, soot blowing need, and temperature excesses which
result in shortened tube life.
Because of its wide dynamic range, the ability to be placed at many locations, and its non-invasive rugged construction, the acoustic system provides flue gas temperatures were other devices cannot.ApplicationsFlame Impingement
Tube erosion or tube corrosion when the flames come into
physical contact with the tubes, causes the life of the tubes
to be greatly shortened. SEI has been installing mapping systems,
our MMP System, to identify this and other heating issues in
the boiler or furnace for several years.
 The picture at the top right is a power plant in Denmark, and the unit on the left is of Avedore #2 in Copenhagen. It is a new (2002) 460MW, Combined Heat and Power (CHP) Plant, burning gas, coal, and oil.
 Our
MMP System, with eight ports and twenty-four paths, is installed
at this ultra supercritical plant to control Flame Impingement,
on the wall tubes. Using a MMP system, the temperature from
wall to wall inside the boiler is mapped in color with Isothermal
lines. A sample of this map, in a slide show, is at the left.
This color map, produced by TMS-2000
Software which is included with the MMP, allows the
operators to maintain an even temperature distribution within
the furnace to minimize tube corrosion and erosion. A larger
image and details of this history, is available here
(760 KBytes). It opens in a new window.
A cutaway of the plant and boiler are also shown, a full page image is available here (211 KBytes).Boiler Performance
Gas Temperature Measurement by traditional methods provide
only "point" source measurements at the physical location of
the sensor, or the case of an optical or radiation pyrometer
the temperature of a black body source (not the air nor the
gas temperature). On the other hand, Acoustic Pyrometers provide
spatial temperature measurements which are in many cases more
useful to understanding and/or controlling the process being
measured. In addition, Acoustic Pyrometers are very robust and
can operate in the high noise levels found in large coal, gas
and oil-fired utilities. The acoustic pyrometer is the only
instrument that can offer reliable, accurate, and repeatable
measurement of high furnace exit gas temperatures on an automatic
unattended basis.
It is also possible to use the data from the acoustic pyrometer temperature reading to manage the firing rate from start-up through the full operating range to avoid hot sections in the superheater. This would provide for superheater protection through the entire load range by utilizing upstream information to manage boiler temperatures.Burner Control and OptimizationAcoustic thermal mapping is being used to provide operators with information for fuel and air balancing, detecting malfunctioning pulverizers, and optimizing tangential burners. One immediate benefit is in keeping the fireball off of the walls in order to prevent wall tube fireside corrosion. The real-time temperature distribution visualization, using an MMP system in the control room, allows meaningful operational changes to be made with an immediate indication of the response.
For example, burners were adjusted during various load conditions in order to achieve optimal performance and minimize wall tube fireball impingement. As a result, the boiler is able to be brought on-line many hours earlier than was possible before the use of the acoustic pyrometer. There is a savings in plant availability as well as plant life extension benefits due to less wall tube fireside erosion.Soot Blower ControlSoot blowing losses can vary a great deal depending on the operator and type of coal burned. Excessive use of soot blowers creates a cost burden on a utility. The cost is incurred using parasitic power from the generating unit. If steam is the blowing medium, less steam flow is available to the generator’s steam turbine, causing less power to be produced. It is estimated sootblowing costs for a 415 MW unit are $1 million to $2 million per year, in addition to boiler efficiency losses. Obviously, soot blowing optimization is of value.
Gas temperature measurements can be used as a direct indication of soot buildup, by installing a two or multiple path system (SP-2 or MMP). The SP-2 is capable of two temperature paths, these two paths could be used to determine the difference in temperature at two areas in the furnace. As the tubes become more laden with soot, less heat is absorbed in the tubes, and the temperature difference decreases. The temperature difference is automatically calculated by the SEI system several times a minute for constant monitoring. The output is a 4-20 mA signal for easy connection to process control. See also Soot Blower Control.Emission Reduction Using Sorbent InjectionSO2 and NOx reduction can be achieved through a variety of combustion and sorbent injections. Temperature is a key in how the sorbent reacts. Please see Sorbent Injection Control for more details.Thermal Probe ReplacementAcoustic Pyrometers provide continuous valuable temperature information during start up, and after the boiler is placed on-line. Our products are rugged, have a long life and very low maintenance. See Thermal Probe Replacement for more information. |
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