Emerson Exchange 365

Let’s talk troubleshooting. At a recent workshop, Daniel Driskell, field service representative for Emerson, and an executive from a large plastics, chemicals and refining company asked the attendees, “How many times has a process or equipment issue arisen and you did not have the proper tools to diagnose the problem?” A lot of heads nodded because it’s a challenge that occurs in almost every plant and application at some time and can lead to increased cost and decreased production.

The problem identified is that wired technology for troubleshooting can be costly for a short-term installation, the design and installation of new wired transmitters is time-consuming, and data from local instruments is less accurate and not easily correlated with online instruments for trend analysis. This adds up to troubleshooting jobs not getting done or being done inefficiently.

The solution suggested by the speaker is wireless. His company installed a permanent wireless gateway a number of years ago. For troubleshooting, they have assembled a pool of 23 wireless transmitters – wireless pressure gauges, DP wireless transmitter, vibration/temperature transmitter, wireless temperature transmitter, and wireless motor amp transmitter. The site had previously purchased this pool of wireless transmitters (pressure, temperature and DP flow) for a process engineering study. These were applied and provided the data needed to understand the process opportunities. These instruments are now used to troubleshoot process problems quickly.

In one case, a poor centrifuge separation of polyethylene from hexane slurry was producing a dropping temperature in the downstream dryer. This poor separation caused a significantly reduced production rate. Here’s how it was solved:

• Installation of several wireless pressure gauges on the dryer system
• Historized the pressure of the wireless pressure gauge with that of the pressure on the liquid discharge vessel (existing wired transmitter)
• Compared the two pressures over time
• Revealed an unexpected reverse gas flow through one segment of the system, affecting centrifuge separation efficiency. Using the data, the problem was traced to an incorrect manual valve lineup.

In a second example, a nitrogen blower capacity was increased in a closed loop system and the increased pressure lifted a conservation vent on a silo. If this continued, it would have created a significantly reduced production rate to prevent vent lifting.

Here’s how the troubleshooting went:

• Install wireless transmitter on top of an 80-foot silo, and replace a local DP gauge with a DP wireless transmitter
• Allow for engineers and operations to easily monitor system pressures, make adjustments, and optimize the gas flow rate to reduce return header pressure drop.
• Following the adjustments, permanent instruments were installed.

The business results of these two cases were impressive:

• Results 1
  • The high reverse gas flow was found to be a misaligned manual valve
  • After correction, they were quickly able to return to benchmark production rates saving over $30,000 a day
• Results 2
  • Using the wireless pool of transmitters as an intermediate solution saved the plant over $18,000 a day in lost production

The wireless instruments provide quality data, are fast and easy to install and preconfigured for Historian, and allow frequent data collection that correlates with other data and is easily shared via Historian. All told, the availability of a pool of movable wireless instruments can be used to quickly provide accurate, near real-time, historized process data to operators and engineers for troubleshooting.

Could you use wireless instruments for troubleshooting in your plant?