Instrumentation - Opacity
June 4, 2004

Introduction

Transmissometers are typically installed to meet the requirements of pollution control agencies.  Opacity data can also be related to process performance.  Data can be used to indicate a need for maintenance or repair, and also serve as a rough indicator of combustion efficiency.  Transmissometers can detect broken bags in baghouses; they can time rapping or flushing cycles for electrostatic precipitators and detect effectiveness of injecting flue gas conditioning agents to improve ESP performance.

Principle of Operation

Transmissometers - A beam of light is transmitted across the process gas to a retroreflector, which in turn reflects the light beam back to the transceiver's multiple lens optical system.  A detector converts the light into a voltage that can be processed along with three other voltages developed from ambient light, lamp, and dark measurements.

Instruments