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美国环境保护署EPA文件
EPA Handbook
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Continuous
Air Pollution
Soure Monitoring Systems
CHAPTER 3
INTRODUCTION TO THE ANALYTICAL METHODS |
3.1 Emission Monitoring
Federal or State regulations will dictate whether an opacity
monitor, gas monitors, or both are required on a given
source. Many sources will be required to monitor opacity
only. In such cases, instrument selection is relatively
easy. since there is only one measurement principle that
will satisfy the EPA opacity monitor design specifications.
On the other hand, selection of gas zaccurately monitors
emissions (accurate,relative to the reference methods
for determining pollutant gas concentration, being defined
in 40 CFR Part 60 Appendix B ).
There are many instruments marketed for monitoring emissions
from stationary sources. Opacity monitors may be either
single-pass or double-pass systems (these will be. discussed
in Chapter 7). Gas monitoring systems may be either extractive
systems, in-situ systems, or remote monitoring systems.
These divisions are shown in Figure 3-1. |
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| TYPES OF SOURCE
EMISSION MONITORS |
Extractive gas monitors were
the first type of instruments to be incorporated into
continuous gas monitoring systems. Many of the
first extractive systems used modified ambient a analyzers.
Or they adapted an ambient air analyzer to source applications
with the use or a gas dilution system. Many problems were
found with this type of approach. Systems were later designed
to deal directly with the problems of extracting,sampling;and
analyzing pollutant gases at source level concentrations.
The in-situ gaseous emission analyzers
are the second generation of instruments designed for
source monitoring. The analysis is performed on
the gas as it exists in the stack or duct (hence,in-situ)
generally by some advanced spectroscopic
technique. These analyzers are installed either
across a stack (cross-stack) or employ a probe inserted
into the flue gas stream (in-stack).
These two types of in-situ analyzers do not extract or
modify the flue gas.
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