Celanese Corporation: Narrows Site Energy Reduction Project Achieves Significant Energy Savings
In October 2017, an internal Celanese team was formed to find ways to improve energy performance at the Celanese Narrows, Virginia, plant. In the past, the plant had primarily focused its efforts on safety, quality and production rates. As a result, improving energy consumption had become a lower priority. The team needed a new approach to successfully change the behaviors at the site to reduce energy usage. They implemented a process called "The 4 Disciplines of Execution" (based on the business book by Chris McChesney, Sean Covey, and Jim Huling), or 4DX, to ensure that they could reach their goal of reducing energy spending by $150,000/month. From October 2017 through March 2018, the team met this goal and reduced energy spending by $945,000 in total, averaging $157,000/month.More
The 4DX (4 Disciplines of Execution) were:
- Focus on the “wildly important goal” – reduce energy costs
- Act on the lead measures, which are the actions taken that drive the lag measure*
- Keep a compelling scoreboard showing the progress of the team’s efforts
- Create accountability with the team members to make and meet commitments to move the lead measures
*Lead measures are action or driver-based measures which if improved or acted on are predictive of the lag measures. Lag measures are indicative of overall result desired and happen after a period of time e.g. energy use reduction or cost.More
To reduce energy usage, the team focused on five key leading indicators:
- Percentage of steam returned to the boilers as condensate
- Steam used per unit of acetone recovered
- Steam used per unit of flake production
- Site electrical usage
- 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%.
The reductions in electricity demand has contributed to reducing peak electrical demand each month. In addition, the site departments have improved coordination of equipment outages and restarts to move peak electrical demand to off -peak periods. For 2018, the peak electrical demand has been reduced by 26% on average.More