Optimizing Energy Consumption with Real-Time Feedback

As energy prices slowly creep higher from earlier lows, the need for managing energy usage remains constant for most process manufacturers and producers. The U.S. Department of Energy’s Energy-Intensive Process Portfolio list processes in the refining, petrochemicals, chemicals, plastics metals, pulp & paper as large energy consumers.

In an earlier post, Identifying Components then Optimizing Industrial Energy Consumption, we highlighted some pulp and paper projects where energy optimization projects were successfully performed.

Emerson's Barbara Hamilton


Emerson’s Barbara Hamilton shared a few more stories of ways process manufacturers and producers are optimizing energy consumption. The first involved a large processing facility that had many large AC motors. Typically, plants use banks of capacitors to keep the plant power factor closer to unity. For those not familiar with power factors, I have a LinkedIn post with a handy visual of real (kW) versus apparent (kVAR) power.

These capacitor banks are typically turned on and off manually since power factor is not typically controlled automatically. This facility worked with Emerson’s Industrial Energy consulting team to develop the electrical target calculation using Energy Advisor EMIS (Energy Management Information System) application.

In trying to identify the right equations, the team noticed that the dynamic gain of electric use vs production rate was constant but the offset (which represents the base electrical use with the plant down) seemed to differ depending upon the data set selected for analysis. The plant’s process engineer thought the bias value should always be constant—how can the base level electrical use change from day to day?

Power Factor Correction Unit, 75 kvar
By Echoray (Own work) [GFDL or CC BY-SA 4.0-3.0-2.5-2.0-1.0], via Wikimedia Commons

After conferring with the operators, they pointed him to the capacitor banks. These should only be switched on if the big motors are running. With all that typically goes on when things are shut down, sometimes the capacitor banks were not shut down—affecting the power factor away from unity.

The Energy Advisor application now acts as a not-so-subtle reminder for the operators. When energy use is above target, they look to see if any capacitor banks can be switched off. Prior to this real time insight, the extra energy consumed by a capacity bank was out of sight and out of mind.

A second story Barbara shared was of a northern hemisphere, northern climate petrochemical plant. It requires the transfer of product and/or utility streams between units. While the layout of various plants often cannot be changed, the impact of heat loss due to changes in ambient temperature is often overlooked.

This plant used Energy Advisor to create the calculations for steam usage in a blending process. The process engineer found ambient temperature had a surprisingly high gain factor on the resulting equation. A bit more digging uncovered that the temperature drops on the product stream could be as high as 12 degC.

Based on this information, the engineer was able to justify upgrading the pipe insulation and prioritizing this project in the priority list of cost-saving initiatives.

You can connect and interact with other industrial energy experts in the Industrial Energy group in the Emerson Exchange 365 community.

One comment so far

  1. You can use a wireless power meter to measure the power factor to stay within limits. Once the wireless sensor network is in place, there are many other things you can do to improve plant energy efficiency using wireless sensors, including feeding the EMIS system with the flow measurements to pinpoint sources of energy loss
    https://www.linkedin.com/pulse/saving-energy-one-bit-time-jonas-berge
    The same wireless network can also be used to improve reliability, energy efficiency, HS&E, and productivity.

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