Unless your plant or production facilities was recently built, chances are that your process has a mix of automatic and manual control. A common area for manual control are on-off valves used in many general purpose applications such as tank filling and emptying, filter backwash and blowback, and sequencing operations to name a few.
In a Control Engineering Asia article, Intelligent On-Off Valves
, Emerson’s Jonas Berge
…how intelligent on-off valves, in conjunction with asset management software, can help reduce unnecessary valve inspection, speed up valve overhaul, and enable shorter turnarounds to be planned in plants.
Traditionally, the automation of manual on-off valves required a bit of wiring:
…with a separate solenoid valve and two feedback limit switches for open and closed positions. However, the feedback limit switches can be challenging to align for correct position indication.
Technology advancements have simplified the wiring requirements with:
…an integrated on-off valve controller mounted on the on-off valve. A low-power piezo pilot valve with spool valve and limit switches are built into the self-contained on-off valve controller protective housing. The single integrated unit simplifies engineering, procurement, and construction which makes it easy to mount on the valve actuator and connect the wiring.
These on-off valve controllers are powered with a single pair of wires powered by the automation system discrete outputs. These valve controllers can be used on a wide variety of on-off valve actuator/valve types including: Continue Reading ▶
The PID controller entry in Wikipedia highlights the beginning of proportional+integral+derivative control going all the way back to the 19th century:
PID controllers date to 1890s governor design. PID controllers were subsequently developed in automatic ship steering. One of the earliest examples of a PID-type controller was developed by Elmer Sperry in 1911, while the first published theoretical analysis of a PID controller was by Russian American engineer Nicolas Minorsky, (Minorsky 1922). Minorsky was designing automatic steering systems for the US Navy, and based his analysis on observations of a helmsman, noting the helmsman controlled the ship based not only on the current error, but also on past error as well as the current rate of change; this was then made mathematical by Minorsky. His goal was stability, not general control, which simplified the problem significantly. While proportional control provides stability against small disturbances, it was insufficient for dealing with a steady disturbance, notably a stiff gale (due to droop), which required adding the integral term. Finally, the derivative term was added to improve control.
PID control remains a mainstay for process manufacturers and producers. In a ControlGlobal.com article, Tuning Finale—What’s Going on With Loop Performance?
, by Greg McMillan and Stan Weiner
, they interview Emerson’s Mark Coughran
and ask him about some of his experiences with challenging applications for PID control.
Mark has had much experience in offshore oil and gas production applications. One of the big challenges for control is the 3-phase production separator to manage the crude oil, produced water, and gas coming from the production wells. One challenge is that local control engineering experience is not typically common. Mark notes: Continue Reading ▶
This week marks the 70th annual Instrumentation and Automation Symposium for the Process Industries at Texas A&M University. The goal of the symposium is to educate professionals and students in the instrumentation and automation industry.
Global Gas Processing Sales & Marketing Director
One of the keynote presentations will be given by Emerson’s Chuck Miller
. He will kick off the proceedings at 8am January 27 with a presentation, Gas Processing Market Assessment. His keynote address explores the natural gas market in North America, the impact of falling oil prices, and the challenge in this economic environment to the automation industry.
Chuck shared an advance copy of his presentation so I’ll highlight a few things from it. Growth in natural gas production in the United States has been massive over the past 5 years. This growth is expected to continue through 2018, particularly with high-BTU “rich” natural gas. Propane, butane and natural gasoline production from gas processing plants has increased by nearly 30 percent since early 2010 and will continue to grow over the next 10 years.
Chuck notes how formations with production diversity—crude oil, natural gas and natural gas liquids (NGLs) can better handle the economic uncertainties involved with rapidly changing prices. Examples of these formations include the Permian Basin and Eagle Ford Shale regions in Texas.
The boom in U.S. crude production over the past three years has been mostly light crude. An increasing portion of this crude output is more correctly termed condensate – a very light liquid hydrocarbon with gravity typically over 50 degrees API. Similarly, the production of plant condensate, also called natural gasoline or pentane plus, has also increased, although on a smaller scale. This increase production of wet natural gas is driving the need for increased processing and fractionation capacity. Continue Reading ▶
It’s likely that you have all the measurement instrumentation devices you need to safely and reliably operate your process manufacturing or producing facility. But perhaps you don’t have all the measurements you need for non-process control/process safety applications such as an energy management program.
In a published paper, WirelessHART® Minimizes Cost of New Energy Measurements
(purchase required), Emerson’s Mark Menezes
highlights some places additional measurements can help improve energy efficiency.
He opens sharing the story of a Canadian power producer, SaskPower who:
…decided they required more than 200 new pressure, temperature and flow measurements to maximize energy efficiency at their plant in Saskatchewan, Canada. Adding these new measurements using traditional field wiring was deemed too costly in cash, time and physical space. Too, the existing control system could not handle additional inputs without significant (expensive) upgrades. Instead, SaskPower used WirelessHART® transmitters.
Mark noted that prior to wireless technologies, new measurements for energy management or other application would be wired to the control system using the HART digital communications protocol. The HART protocol is used in more than 80% of the smart devices shipped from more than 200 instrumentation suppliers.
WirelessHART, release in HART Revision 7: Continue Reading ▶
In 2011, the U.S. Food and Drug Administration (FDA) issued a Guidance for Industry – Process Validation: General Principles and Practices. It highlighted a third validation stage goal of continued process verification (CPV) for:
…continual assurance that the process remains in a state of control (the validated state) during commercial manufacture. A system or systems for detecting unplanned departures from the process as designed is essential to accomplish this goal.
We touched on aspects of continued process verification in earlier posts
. I caught up with Emerson’s Zuwei Jin
for his thoughts. He notes that this guidance has had a fundamental impact on the pharmaceutical and biotech industries. This is due to the fact that the guideline extends a different dimension into the validation lifecycle than the drug development lifecycle itself.
The impacts are around three main areas: process development, engineering design practice, and manufacturing operation.
He explained that the FDA started to request more and more statistical analysis for Pharmaceutical Quality/Chemistry Manufacturing and Controls (CMC) submission and science-based proof for proving that the process is in a state of control.
Zuwei has had conversations with product development (PD) scientists, statisticians, and manufacturing operations personnel from several of the world’s leading pharmaceutical companies. To address these requests for increased statistical analysis and proof, initiatives such as quality by design (QbD), design of experiments (DOE) and CPV are clearly where manufacturers in the Life Sciences industry are headed with their process development and manufacturing operations. Continue Reading ▶