On-line Boiler Monitoring Improves Efficiency and Reduces Pollutants – Hot Topic Hour on September 13
Speakers in the Hot Topic Hour September 13 described instrumentation and systems which control the air and coal flow in a coal-fired boiler so as to reduce pollutant generation and improve boiler efficiency.
David Early, President of Combustion Technologies Corp., pointed out that several parameters critical to boiler control that were not available only a few years ago — the on-line, continuous measurement of burner line coal flow as well as the associated individual burner secondary airflow. Measurement and control of these parameters allows for controlling the air-to-fuel ratios of each burner. The continuous control of A/F ratios allows for balanced excess O2 readings and minimizing/eliminating CO. This, in turn, allows users to reduce the O2 that yields a reduction in NOx and improvement in boiler efficiency and fuel savings. Continuous measurement of the coal flows also allows for elimination of coal layout (and pipe fires) optimization of primary air; better flame stability and more. In order to ensure optimized combustion, continuous measurement of CO should also be performed as it is a more reliable combustion tool than excess O2 alone. Benefits include heat rate improvement, lower risk of fires, reduced noise and lower pollutants per MWh of electricity produced
Todd Melick, Vice-President of PROMECON USA, Inc., discussed the PROMECON carbon in ash monitoring system and air and flue gas flow measurement for dusty applications, a new modification that allows measurement with clean air while starting up a boiler or coal mill. He also reported on the application of balancing flue gas flow into various scrubber modules on a recent project. The accurate flow measurement is an important process parameter and allows the operator to balance flow between the various modules. The carbon-in-ash monitor can measure the carbon in each of the precipitator hoppers. If the final hopper contains levels of carbon which are too high for resale, this portion can be separated from the salable balance.
Scott Affelt, Vice-President of Sales and Marketing at Zolo Technologies, discussed a laser-based sensor that can measure temperature, O2, CO and H2O profiles directly in the furnace and in real-time. This key combustion constituent information can be used to balance combustion profiles to reduce emissions, reduce slagging or improve efficiency. The information can also be integrated into a closed-loop combustion optimizer to maintain optimum combustion performance over a range of operating conditions and fuels.
It is a low maintenance system since the equipment is all outside the boiler. A recent system was just proven to be cost effective in an installation in China involving a 600-MW supercritical unit. Some of the cost savings is a result of the high cost of coal ($100/ton). Since the unit is already quite efficient there was some skepticism initially that the system could be justified. But it has now proven its value.
The entire September 13 recording can be heard at: Instruments and Technology for On-Line Boiler Monitoring – 97 minutes – Password: hth704
The Bios, Abstracts and Photos can be seen at: BIOS, ABSTRACTS, PHOTOS - September 13, 2012.htm
The individual presentations are as follows: