Stay out of trouble with process analyzers

Contributing Editor Wayne Labs reports that whatever the process variable or constituent to be monitored, process analyzers are out of the lab at last and ready to improve processes in real time.

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By Wayne Labs, Contributing Editor

MODERN PROCESS analyzers help manufacturers meet federal regulations, whether to meet EPA emission control requirements for power plants and refineries, or to guarantee consistent product as the FDA requires of the pharmaceutical industry. To meet these application requirements, the old stay-in-the-lab analyzer has evolved into the on-line process analyzer that works right at the process. With advances in communications, sensors and software, these on-line devices make it possible for manufacturers to get up-to-date information to make intelligent manufacturing decisions.

Continuous Monitoring
One class of process analyzers, the continuous emissions monitor (CEM), checks for NOx and other greenhouse gases in stack emissions. Some manufacturers have put off installing them only to find out they must face court proceedings initiated by the federal government. For example, a consent decree filed by the U.S. District Court for the southern district of Texas ordered Equilon (a refiner headquartered in Houston to begin a four-year study to optimize the performance of its Selective Non-Catalytic Reduction (SNCR) system to minimize NOx emissions in its Martinez, Calif., facility by no later than June 30, 2001. To get started, the company had to install process analyzers to report continuous NOx and O2 data to the EPA in electronic format.

Even when manufacturers install these devices willingly, they still face a host of government regulations. Kenneth J. Clevett, process analyzer consultant for FIT Consulting, Inc. has more than 41 years of experience in refining and petrochemicals. “CEM systems are required to meet EPA regulations regarding calibration and documentation of releases,” says Clevett. “So great care must be taken in their design to ensure that the system will meet all these EPA requirements. The onus of responsibility is on the user, since the government will only approve or reject the installation on a one-by-one basis after it has been installed.”

Local and state governments are clamping down on polluters, too. To achieve federally mandated ozone attainment compliance in the Houston-Galveston area, the Texas Commission on Environmental Quality (TCEQ) is mandating the reduction of highly reactive volatile organic compounds (HR-VOC) emissions from process flares and cooling water. These new regulations call for the on-line measurement of the total VOC, specific HR-VOC, and total HR-VOC. The TCEQ ruling specifies that a QA-Plan should have been submitted before April, 2005, sites must start measuring HR-VOC and BTU contents by the end of 2005,  and be in compliance by April, 2006. Cooling towers over 8,000 gpm and flares must be measured individually every 15 minutes.

FIGURE 1: PROCESS GAS ANALYZER
Siemens’ FIDAMAT 6 measures THC in a gas stream, including trace measurement of hydrocarbons in pure gases, emissions monitoring, and THC in corrosive gases.


Two types of process analyzers that can be applied in cooling towers and flares are gas chromatographs (GCs) and flame ionization analyzers. Gas chromatographs can measure the chemical composition of just about any form of liquid or gas, and can be used to monitor areas, waste gas streams, waste and cooling water. Flame ionization systems are particularly good at measuring total hydrocarbon content (THC) in a gas stream at high temperatures and with up to 100% water vapor (See Figure 1).

Pharma Puts Analyzers Online
More regulation is coming to the pharmaceutical industry. Process Analytical Technology (PAT) is an FDA program that promises better quality control of pharmaceuticals and will require the use of online process analyzers. Begun in part by Ajaz S. Hussain, Ph.D., deputy director, Office of Pharmaceutical Science, CDER, FDA, PAT is a system for designing, analyzing, and controlling manufacturing through timely measurements of critical quality and performance attributes of raw and in-process materials and processes with the goal of ensuring final product quality. Thus, PAT allows for continuous process manufacturing improvement.

The PAT program will do for the pharmaceutical industry what similar process improvement programs have done for other industries. According to Honeywell Process Solutions Life Sciences marketing manager Mark Albano, the approach defined in the PAT initiative is consistent with approaches that have been used by other industries to improve control of their processes. The program goes beyond just process measurements, and includes all aspects of effective process automation and information management.

While off-line testing refers to lab-based checks, at-line, in-line, and on-line are three terms used in describing the degree of connection of the analyzer to the process stream. In a Web-based paper, Peter Scott, quality assurance analytical services, AstraZeneca, Westborough, Mass., points out the differences. “The first step away from off-line testing (laboratory separated from the production plant), is at-line testing. This is the movement of process-dedicated testing equipment to the production line to provide rapid results. One advantage is elimination of the transfer of samples involving time delays.

Along with traditional tests such as dissolution, assay, friability, hardness, and thickness, at-line testing could also include accelerated dissolution rate analysis and NIR tablet analyzers. One approach of process analytical chemistry is on-line testing, which either draws samples or monitors periodically. Another mode is in-line testing, which places probes in constant contact with drug product. The advantage of on/in line testing is better control of the process.”

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