To reduce energy usage, the team focused on five key leading indicators:

1. Percentage of steam returned to the boilers as condensate
2. Steam used per unit of acetone recovered
3. Steam used per unit of flake production
4. Site electrical usage
5. Site peak electrical demand

The team first focused on increasing the percentage of condensate returned to the boilers from the production areas. The site has historically averaged 45% condensate return and set a goal of increasing this to 55%. In September, 2017, the team found that 63% of the plant’s condensate return systems were functional. The team worked with operators, engineering and maintenance personnel to trouble shoot, schedule and repair each of the failed systems and by March of 2018 they had 100% of the systems operational again.

The team then used the 4DX process to isolate and repair failed steam traps and steam/condensate leaks. The site increased condensate return by 4% over this period.

In the Solvent Recovery department, the volume of steam per pound of acetone recovered for each piece of equipment was reviewed to determine which equipment had the highest steam usage. The team embarked on a series of projects including maintenance repairs, optimizing setpoints and shutting down unneeded equipment to improve energy performance. By the end of 2018, steam usage for the Solvent Recovery department was reduced by 20% through these efforts without any decrease in solvent quality.

In the Flake production department, an investigation of the process was completed to determine why steam use was above historical levels. A goal was then set to minimize steam use while maintaining product quality. This included redirecting recycle streams to different parts of the process to reduce energy requirements, increasing use of the distillation automatic process control system and increasing the on-stream time of area heat recovery systems. By the end of 2018, steam usage in this department was reduced by 36% (“CC” standing for Flake Production, below).

In the Utilities department, the team worked to reduce total electricity used and to reduce peak electrical demand. The utilities equipment was optimized to provide the site with the required steam, electricity, refrigerated brine and compressed air while reducing the total cost of purchased electricity. To do this they reduced the number of online air dryers, river water pumps, boilers, and refrigeration machines. A compressed air system strategy was developed to minimize the total power required by the air compressors to meet the site air demand. Charts were added to the plant data historian to increase the visibility of air compressor power consumption and allow quicker response to issues. For 2018 the site electrical demand has been reduced by 5%.