Yokogawa Multi Channel Oxygen Analyzer System ZR22/AV550G - Manual (Page 16)

IM 11M12D01-01E 1-1
1. Overview
1. Overview
Zirconia oxygen analyzers are used in combustion facilities to measure the flue gas
oxygen concentration. Boiler operators use the oxygen measurement to optimize fuel
usage, minimize atmospheric emissions and reduce energy consumption.
A multiple point oxygen measurement system may be required for situations when gas
stratification in the flue duct affects combustion control. The AV550G Averaging
Converter can accept inputs from up to eight zirconia oxygen detectors. It sends output
signals for the individual as well as averages of multiple oxygen concentrations. A
robust multipoint converter reduces installation and maintenance costs.
A large 5.7-inch color LCD display shows various measurement, setup, calibration, and
trend screens. Its intuitive touch screen is easy to read and makes set up and mainte-
nance simple. Other standard features include new self-diagnostics and a hot swap
function that allows a desired probe to be disconnected/reconnected for inspection or
maintenance just by turning off the power of the relevant channel.
The ZR22G separate-type detector uses a highly reliable zirconia sensor and its heater
assembly can be replaced in the field. The in situ probe is mounted on the duct wall and
directly measures the oxygen concentration of a sample gas at a temperature of up to
700
ЊC. For higher temperature applications up to 1400ЊC, the ZO21P-H High
Temperature Probe Protector is available for use in conjunction with a 0.15-m ZR22G
general-purpose detector.
The averaging converter system is ideal for combustion control in large utility boilers or
various industrial furnaces.
This chapter explains system configurations with some typical examples.
1.1 System Configuration
The AV550G Zirconia Oxygen Analyzer Averaging Converter system can be configured
by selecting detectors and an averaging converter that meet the individual requirements
and flow setting units for calibration.
Subsection 1.1.1 presents a typical system configuration using flow setting units for
manual calibration. A typical system configuration to perform automatic calibration is
provided in Subsection 1.1.2.
1.1.1 System Configuration Using Flow Setting Units for Manual Calibration
This system consists of detectors, an averaging converter, and flow setting units (Model
ZA8F), as shown in Figure 1.1. Note that the ZA8F Flow Setting Units are required as
many as the detectors connected to the averaging converter.
A reference gas needs to be supplied at a constant flow rate to the detectors. This
reference gas must be clean, dry air having a constant percentage of oxygen. Typically,
instrument air that has been dehumidified down to a dew point of approximately -20
ЊC
and is free from oil mist or dust, is used as the air source. This air is also used as a span
gas for the detectors during calibration. A zero gas for calibration is supplied from a
cylinder to the detectors.