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The EPRI Compliance Assurance Monitoring (CAM) Field Evaluation Project

The EPRI Compliance Assurance Monitoring (CAM) Field Evaluation Project is designed to evaluate two distinctly different technologies for formulating a CAM plan for particulate emissions for coal-fired utility boilers. The two technologies are (1) a series of computer-based models for predicting ESP performance and (2) a group of continuous PM monitors that produce electrical signals proportional to particulate mass concentration. Numerous, manual particulate emission tests, performed in accordance with EPA Method 17, will provide the focal point of the field evaluation project by serving as the basis for comparision of the two methods.

The project is being conducted at a coal-fired electric utility plant in the Southeast. Specifically, the work is being conducted on Boiler No. 7 at Georgia’s Power’s Plant Yates. Boiler No. 7 is a T-fired boiler with a rated capacity of about 360 MWe. The unit is equipped with a cold-side electrostatic precipitator (ESP) for control of particulate matter (PM). The allowable particulate mass emission rate is 0.24 lb/106 Btu, and the normal emission rate is approximately 0.01lb/106 Btu. This wide compliance margin will permit considerable flexibility in setting up the boiler and ESP for testing.

The ESP Model Calibration Process

It has been shown over the past several years that the available ESP models can be calibrated to a given coal and ESP operating conditions. What is not known is the "range" of the models over a variety of conditions. For example, given adequate emissions test, particle sizing and ESP electrical data, a model can usually be calibrated to produce a perfect fit to the test data. This is done by adjusting certain fitting factors (primarily rapping reentrainment and sneakage) in the model. After calibration, the model can be used to evaluate changes in general operating condition such as stack flow, inlet particulate loading, addition of plate area, loss of electrical fields and variations in ESP power. The magnitude of impact on ESP performance, either positive or negative, can be clearly seen with the models. But, the accuracy of these "off calibration" predictions has never, at least publically, been documented. (Private data show that the models do a very excellent job of predicting ESP performance for plate area additions and field splits.)

To meet the project objectives, a series of field tests will be performed. The test design will evaluate the two primary performance reduction modes of an ESP - complete shorting of electrical sections and reduced power in all sections caused by unfavorable fuel or flue gas conditions. All tests will be run at nominal full load. A general demonstration test protocol is shown below. This test protocol is much more elaborate than one might expect for a final CAM calibration protocol because it is designed to evaluate a broader range of conditions than would otherwise be necessary. For example, it will likely not be necessary to perform particle sizing tests to calibrate the model because coal-fired utility boilers produce similar sized ash particles and a default particle size distribution is usually satisfactory.

Calibrating the Continuous PM Monitors

The continuous PM monitoring systems are located at the same level where the manual stack testing is performed at the field test site. The location is about 300 feet above grade, and the stack diameter is nominally 16 feet. The continuous PM monitors will be calibrated in accordance with EPA’s proposed Performance Specification (PS) 11. According to PS 11, a continuous PM monitor must be initially calibrated by conducting a total of at least 15 reference method (e.g., Method 17) particulate tests at three or more different particulate mass concentrations (e.g., low, mid, and high). Then, a calibration curve is developed by performing a least squares regression on the continuous PM data and the reference method data. PS 11 requires the following for an acceptable calibration relationship.

  • The correlation coefficient shall be 0.90.

  • The confidence interval (95%) at the emission limit shall be within 10% of the emission limit.

  • The tolerance interval at the emission limit shall have 95% confidence that 75% of all possible values are within 25% of the emission limit value.

Reference method testing, which will provide the data for the intital PM monitor calibration was completed in early June 1998. We plan for the continuous PM monitors to be operated several (~ 3) months after initials calibrations. RMB will evaluate the operability and reliability of the continuous PM monitors and prepare a final project report presenting the results of our findings.

Contacts

The EPRI Project manager is Mr. Chuck Dene (650) 855-2425.

For additional information about the continuous PM monitors being evaluated, contact Ralph Roberson (919) 510-0376 - roberson@rmb-consulting.com.

For additional information about the ESP model being calibrated and CAM requirements in general, contact Richard McRanie (919) 510-0483 - mcranie@rmb-consulting.com.

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Last Revised: January 15, 2003