(39f) Operation and Maintenance of Environmentally Critical Process Analyzers

Process analyzers are ubiquitous in any large petrochemical manufacturing plant.  Process analyzers are on-stream instruments that provide real-time analytical data on process streams to control the process to ensure safe, reliable and efficient operation.  For most manufacturing plants process analyzers are also mandated license-to-operate requirements for compliance with federal and local environmental rules to monitor and quantify air pollutant emission from various sources.   Mandated process analyzers used for measuring air pollution emissions from emission sources such as furnace stacks, flares and, cooling water towers are referred to here as environmentally critical process analyzers.  The focus of this paper is analyzers that measure concentrations of specific pollutants: NOx, SOx, CO and VOC’s (Volatile Organic Compounds).   A subset of VOC components; Ethylene, Propylene, Butenes and Butadienes, are also referred to as Highly Reactive VOC’s or HRVOC’s.

A key distinction between analyzers used for process control and environmentally critical analyzers is that while operation and maintenance of process control analyzers is entirely within the discretion of  plant management, specific rules govern installation, calibration, operation, maintenance, quality assurance/quality control (QA/QC) and record keeping requirements for environmentally critical analyzers.  These rules mandate specific daily, quarterly and yearly activities to ensure analyzer data accuracy, and procedural requirements to take corrective actions when an analyzer is determined to be malfunctioning. 

In this paper, we will discuss some of these rules in relation to the technology, operation and maintenance of two types of environmentally critical process analyzers: CEMS (Continuous Emissions Monitoring Systems) that are used to monitor NOx, SOx and CO emissions from stacks, and HRVOC GC’s (Gas Chromatographs) designed to monitor VOC emissions from cooling water towers and flares.