Control System Upgrade Yields Greater Sustainability and Output
When my team formed Carbon Green BioEnergy LLC, we had a vision to own and operate an ethanol plant. We raised enough equity to purchase a mothballed, two-year-old plant in Lake Odessa, Michigan, that had been sitting idle since it went bankrupt in 2008. CGB purchased the plant in 2009 at a time when many thought the ethanol boom was going bust. However, we strongly believed in the future of ethanol as a sustainable, clean fuel that creates jobs and reduces the country’s dependence on foreign oil. Today, our vision for the future has fueled a benchmark plant turnaround that is yielding outstanding results for the company and the community.
In June 2009, CGB took possession of the plant and needed to get it back up and running in a matter of months. This was no small task, as the facility had to be repaired, cleaned, tested, inspected and certified after being unused for a period of time. Once the plant was cleared for production, CGB discovered it wasn’t operating at capacity. It was producing 37 MMgy when its nameplate capacity was 50 MMgy. We knew we had to increase the plant’s efficiency and productivity across the board to make it sustainable and profitable in the long term.
One of our main goals has been to enhance the local economy and community by working every day to improve our plant and our process. We want to be part of the solution to our energy needs in the United States and so we embarked on a plant overhaul that included:
• Upgraded process control system.
• Increased grain storage capacity from 400,000 bushels to 4 million bushels.
• Used the heat and steam from drying the distillers grain to supply a heat recovery steam generator that creates electricity for the plant.
• Streamlined production by increasing throughput to a point where we're diluting our natural gas cost and our electrical cost-per-gallon of ethanol produced. For example, a motor running is going to draw its electricity base load to power a pump. Once that motor is running at an optimal speed, the efficiency goes way up and you can pump 600 gallons a minute versus 500 gallons a minute.
The plant was built with an APACS-plus process control system that was reaching its end-of-life. This means the original equipment manufacturer would not support the technology and software for the long-term. We had three options:
• Keep the existing system, and stock up on spare parts and hope for the best.
• Replace the entire process control system and hardware, which would be costly.
• Take a hybrid approach of upgrading the software while keeping the existing hardware.
The hybrid path is the one that we chose. It enabled us to upgrade the process control platform and interfaces, while keeping existing automation equipment, hardware and input/output (I/O) intact––the communication between the process control system and a field device like a motor, pump or flow meter. The hybrid approach allows us to continue to have the latest software and support while using our relatively “new” and existing hardware and I/O.
We chose to migrate to a Siemens PCS 7 APACS-plus OS to realize the following advantages:
• Upgraded human machine interface (HMI) graphic screens provide a more user-friendly interface. HMIs are computer graphic interfaces used to monitor and control processes on the plant floor.
• Reduced configuration, startup time and maintenance complexity.
• Updated client or server architecture while using the existing APACS-plus control system.
• New process control (PC) operating system.
The HMI upgrade enabled us to extend the life in our installed APACS-plus control system assets with no disruption to production, all while using a new PC operating system. We didn’t need to make changes to the APACS-plus project configuration or field I/O hardware, which reduced testing, outage time and cost. We ran the former HMI system and the new system side-by-side for three months to ensure we were confident the system was performing as designed. We fully transitioned to PCS 7 during a scheduled two-day plant shutdown.
Additionally, Siemens supplied many of the premium efficiency electrical motors that power the pumps and processes within the plant and are connected to the PCS 7 to ensure the most in uptime and energy efficient operations. The Siemens system helps our staff with troubleshooting and operational consistency and efficiency. The team here really likes that. They also like that it's quicker and there's no lag in the control system. It’s pretty bulletproof.
Trident Automation Inc., Kaukauna, Wisconsin, was involved with the startup of the original system so they were familiar with its features and functionality and were instrumental in making the migration seamless. They also helped to effectively and quickly train the operators on the new enhancements available in the new system.
Carbon Green BioEnergy has increased its production from 37 MMgy in 2009 to 55 MMgy today—and we intend to increase production to 60 MMgy by 2015. Other benefits from the new system include:
• Enhanced trending and data analysis make it easy for operators and the process/management team to manage production and troubleshoot.
• Alarm management tools help to identify issues more accurately and improve production. Think of an alarm that tells you a motor needs maintenance, or a process is not running optimally. This helps the maintenance team to fix or repair a problem before it stops production.
• The historian interface has improved the ability to fine-tune the process and improve consistency and energy efficiency by looking at a process over time and understanding how to make it more consistent.
• The Siemens software update service enables us to keep our control software up-to-date at a fraction of the cost of buying new. This enables CGB to streamline its Microsoft security patches and keep the Microsoft operating system current.
Since we installed the PCS 7, we’ve been able to more quickly debottleneck the facility and improve energy efficiency. Basically, we’ve been able to take the waves or variances out of the process and it has enhanced the controllability and reliability of the plant.
With the plant running optimally, we support 450 local farmers, most within 50 miles of the plant, by purchasing 18 million bushels of corn annually at a market value of more than $100 million. This helps the local agricultural community have a stable buyer at fair market price. Growing corn in the area is profitable again and this is good news for the community.
Author: Mitch Miller
CEO, Carbon Green BioEnergy, LLC
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How Sustainable is CGB's Ethanol Production?
Ethanol Production Creates Food & Fuel
• 100 percent of Carbon Green BioEnergy’s corn starch is used for ethanol production. The plant produces enough E85 to fuel a
2012 Chevy Malibu for 1 billion miles.
• 100 percent of the corn’s protein, fat and fiber is made into DDGS, enough to provide a highly nutritious livestock feed to as
many cattle needed to feed 2.2 million people annually.
• CGB uses brewery waste from nearby Beer City USA in Grand Rapids, Michigan, to make ethanol and distillers dried grain.
• Uses only corn from local farmers, mostly within 50 miles.
• CGB uses waste heat from the DDGS drying process to make steam for the plant.
• With tighter process controls, CGB has increased ethanol production without increasing water consumption.
• 2014 energy return on investment is 2.82. The plant gets 2.82 Btu in output for each Btu of input.
• Produces 55 million gallons of ethanol/year.
• Buys 18 million bushels of corn/year from 450 local farmers ($100 million).
• 4 million bushels of grain storage.
• Near zero waste.
• Blends 500,000 gallons of E85 onsite each month.