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• Resistivity and Particle Size Introduction
• Function of Temperature
• Fig. 1: Temp. vs. Resistivity
• Resistivity in Simulated Flue Gas
• Table 1: Coal and Ash Chemistry
• Fig. 2: Resistivity vs. Electric Field
• Fig. 3: Resistivity Model
• Particle Size Distribution
• Fig. 4: Bahco Particle Size

Since the performance of many precipitators deteriorates when the resistivity value exceeds 2 x 10¹⁰ ohm-cm, resistivity data are used in many ways:

• Coal selection Flue gas conditioning Evaluating thermal effects
• Precipitator trouble shooting, etc.

Resistivity data are also used in the selection of allowable voltage/current relationships for computer modeling of precipitator performance.
The recommended sample for particulate characterization is a proportionately blended hopper sample representing inlet through outlet hoppers for a given precipitator chamber. Knowing the electrical section and hopper layout and the design or measured efficiency, calculations are made to determine the amount of dust to use from each hopper to reconstruct the original inlet sample. The blended hopper sample is large enough to permit a variety of tests to be conducted. Isokinetically obtained samples, individual hopper samples and samples removed from wires and plates are also useful for specific purposes.Other available particulate characterization techniques include:

• Chemical analysis True particle density Scanning electron microscopy
• X-Ray diffraction

Unique resistivity tests involving collection plate sections or unusual test conditions and procedures.

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