Minimizing Electricity and Steam Costs

Trying to manage energy consumption and steam usage in a manufacturing process can be a tricky undertaking. The need to do it is ever increasing with higher fuel costs. A recent AEI Environment Policy Outlook study shows the gas and oil price trends over the past 25 years.

The variables operations staff typically must juggle include process load requirements, multiple fuel types, boiler/turbine availability and efficiency levels, and electric buy/sell prices to name a few. Of course, steady state operations are rarely possible because product mix and volumes being produced are normally in flux.

You may recall Bob Sabin, a consultant in Emerson’s Industrial Energy Solutions organization, from an earlier post on Chemical Recovery Boilers. Bob discussed how the team of energy consultants works with process manufacturers to develop facility specific models and rule sets to continually determine the optimum operating setpoints for all the process units.

They have packaged their approach into a SmartProcess Energy application that is used to reduce the total cost of energy in a mill/plant by automating critical decision-making. The energy optimization process begins with a review of existing Powerhouse operations and recent operating data. The consultants use off-line modeling tools to evaluate improved operating methods and estimate the level of savings that can be achieved. The effort reviews the fuel alternatives, purchased versus produced power options and constraints, and the current decision making process for optimizing energy and steam production and usage.

Bob said that a key to Emerson’s energy optimization approach is extensive data validation to help the application tolerate measurement errors and device failures. The decision making rules for optimum operation are implemented using mathematical models running within the automation system controller.

He pointed to two areas of savings. The first is identifying large opportunities for cost improvement such as changes in fuel type usage. Perhaps more important is the second area, which is the constant small adjustments being made to process setpoints in real-time. This helps move the total operation to its absolute best cost point based on current constraints. These are adjustments that could not easily be recognized by the operators.

The Industrial Energy Solutions team has documented typical annual savings of $500K to $2MM USD where the SmartProcess Energy application has been applied.

Posted Monday, August 14th, 2006 under Process Optimization.