Process analysis gains greater online role

It’s not just progress in the technology that is spurring the acceptance, notes Roy Muston, senior automation consultant with Shell Global Solutions (U.S.) Inc. “The [drive] to run process units at maximum capacity and higher yields has increased the need for process analyzers,” he explains. At the migration’s heart lies technology transfer. The telecommunications indus-try and low-cost lasers for spectrometric use drive that transfer says Terry McMahon of PAI Partners, Leonia, N.J. He specifically points to the role that small, rugged telecom-munications spectroscopic components are finding as process analytics tools.

McMahon cites in particular Axsun Technologies, Billerica, Mass. That firm of-fers the IntegraSpec XL micro-spectrometer for general process applications and the In-tegraSpec XLP micro-spectrometer for meeting U.S. Food and Drug Administration’s process analytical technologies (PAT) requirements. It already is being used is in the dry-ing process for active pharmaceutical ingredients to meet PAT monitoring goals.

Encoded-photometrics infrared (IR) spectroscopy also offers promise. “Every-body is making a big deal about it, but it’s way too early to determine its impact on the chemical industry,” cautions Menlo Park, Calif.-based Steve Walton of PAI.

Even so, Aspectrics, Pleasanton, Calif., with its MIR-1 encoded-photometrics IR spectroscopy analyzer, grabs his attention. “Encoded IR mimics FTIR (Fourier Transform IR) spectroscopy,” Walton explains. FTIR typically has been used in the laboratory to measure organics through absorption of various infrared-light wavelengths. Encoded IR’s claim is that it attains the resolutions and separations normally found with FTIR but does so online, he adds. One potential use is for ambient air and stack-gas monitoring —  for example, hydrocarbons speciation in homolog gases such as butane, pentane, etc.

Other technologies garnering greater interest include process mass spectrometry, including FT mass spectrometry (FT MS), which also is called FT-ion-cyclotron-resonance MS (FT-ICR MS), and nuclear-magnetic-resonance online processing, which also is known as industrial magnetic resonance. Meanwhile, a new platform for sampling is attracting attention. Dubbed  New Sampling/Sensor Initiative (NeSSI), it combines modularity with micro-analytics and intelligent sensing and communications.

However, Walton notes the chemical industry is conservative, a relatively slow adopter. “They’re not going to put in anything that will undercut their operations — or something they can’t maintain.” Safety, reliability and cost are the biggest current chal-lenges for process analytics, adds McMahon.Nevertheless, these and other technologies are increasingly capturing industry’s fancy and promise to fundamentally change process analytics.

Minutes, not hours

The just-released FastGC (Figure 1) from ABB’s Process Automation Division, Lewis-burg, W.Va., certainly aims to play a significant role in continuous online analysis. “It does simulated distillation analysis of refinery crude and products,” explains Damian Huff, product manager. Laboratory analyzers now used to verify liquids’ distillation pro-files typically require two to three hours from sample collection to analytical results, he estimates. “Our instrument gives results every three to five minutes.” FastGC, which Huff says has a 99+% operating availability, fully networks with Ethernet, so real-time data can be displayed at operators’ workstations.

Figure 1. This unit provides results in 3 to 5 minutes, not the hours typically required.

The instrument can handle analyses for many refinery operations. However, it’s not suitable for heavy distillates, Huff notes. “We typically will measure liquids with a final boiling point of 470°C. It’s difficult to measure anything with a higher boiling point because it’s difficult to vaporize the sample,” he explains.

One potential use of an instrument like ABB’s is to monitor pipeline blending, in which refiners use the run-of-pipe from tank farms to transport vessels for final blending. This approach promises to save on tankage as well as offer better control of the blend but depends upon fast analyses. “Refiners produce fuels and put them into a blending tank. But because their old laboratory-based distillation analyses were [15-30 min.] aged, they could not realize the benefits of pipeline blending,” Huff explains.

Resonating results

Magnetic-resonance-imaging-based technology like that used in hospitals also is finding its way into plants. Invensys Process Systems, Foxboro, Mass., offers Process Magnetic Resonance Analysis (MRA) (Figure 2), which can analyze the composition of crude and final products at refineries, as well as streams at chemical and pharmaceutical plants, says Joe Fillion, who is responsible for worldwide sales and marketing.

ConocoPhillips installed a Process MRA at its 185,000-bbl/d refinery in Trainer, Pa., to analyze diesel and kerosene streams from two crude-oil distillation towers. “With some things we were measuring, we didn’t feel like we could [do those well] with in-ferred properties,” explains Tim Lowell, plantwide control systems engineer. “On our kerosene stream, naphthalene was measured with a smoke test,” he adds, noting he’s never spoken to anyone who’s ever successfully used that test. “That was the main thing that moved us to get the analyzer.”