Distillery retains tradition, but upgrades control system

While making bourbon is steeped in traditional practices, Four Roses likes to keep its automation up to date.

By Ken Keiser, Siemens Industry April 13, 2011

Since the late 1880s, the smooth and mellow taste of Four Roses Bourbon has been a favorite among whiskey lovers. Over the decades, the spirits distiller has seen numerous management and political changes—including being one of only six distilleries granted permission to operate through prohibition to produce bourbon for medicinal purposes.

Speaking with the people who work at the Four Roses Distillery in Lawrenceburg, KY, it is clear one thing has never changed: a passion for quality and pride in creating and producing the award-winning bourbon that is the legacy of founder Paul Jones, Jr. Four Roses is the only bourbon distillery that combines five proprietary yeast strains with two separate mash bills to produce 10 distinct and handcrafted bourbon recipes. Each bourbon recipe has its own unique character, spiciness, and flavor.

Ensuring uninterrupted production with consistency and quality at the 24/7 distillery is top priority for Ryan Ashley, Four Roses director of distillery operations. He says that since 1999, the facility has relied on an APACS+ automation system. Although the system’s controllers, I/O, software, and HMI (human-machine interface) all worked perfectly, the company decided that the time had come to move to a new platform when it learned that the hardware and software would soon be phased out.

Upgrade for the future

The distillery began a migration strategy in 2008 that upgraded to Siemens’ Simatic PCS 7 DCS (distributed control system), while retaining the existing controllers, I/O, and field wiring. The original HMI was replaced with a PCS 7/APACS+ OS HMI that allowed Four Roses to continue to use its installed controllers without making modifications to the application software. “By putting PCS 7/APACS+ OS on top of the APACS+ controllers, we saved thousands,” Ashley says. “We also cleared the way for the next phase that would replace the controllers with PCS 7 controllers.”

In 2010, Ashley installed APACS+ DP I/O Bus Link from Siemens Industry, which allowed Four Roses to upgrade its existing controllers and continue to use the remaining installed I/O modules and field wiring. Ken Keiser, Siemens process automation migration manager said, “Rather than rip out and replace the existing APACS+ system, Four Roses used the I/O with the wiring in place. They also had significant savings in the checkout because they eliminated the engineering work to make sure that every loop was correct.”

Four Roses now has the enhanced process control capabilities of the PCS 7 DCS, including the flexibility and added capacity of multiple scan rates up to 10 ms. The modernization also provides higher fault tolerance, flexible modular redundancy, higher safety (SIL 3 independent of redundancy), integrated asset management, integrated safety fieldbus, and integrated Ethernet.

Ashley, who also has received international awards for brewing beer, said nearly every element of the distillation process is automated by the PCS 7 DCS because of the I/O Bus Link upgrade. Operators monitor and control the distillery process from one central control room and two workstations located at different levels of the facility. “We’ve been making the same bourbon since 1888 and we didn’t want to change what worked in the past,” Ashley says. “Some of our operators have been here more than 40 years. It was important that the changeover was a non-issue for them and we didn’t miss a beat. The screens at each workstation are the same as before the bus link installation.”

Making award-winning bourbon

“While the fermentation process involves manually opening and closing valves, operators use the DCS to control the grain handling system, the mills, the cooker, temperatures, agitators, and pumps. Everything is tied into the PCS 7 system,” Ashley says. The distillation process begins when corn, malted barley, and rye undergo two different mash cooks. He adds that Four Roses has a higher percentage of rye in the rye mash than any other distillery, giving the final product a very spicy finish. The process cooks these cereal grains, making starches and carbohydrates available for yeast to metabolize later in the process. “We are hitting upward of 212 to 146 °F to activate certain enzymes that are available in the grain and ultimately make those starches available. Starches are long chains of carbohydrates or sugars that the yeast will want to eat later to produce the alcohol.”

The mash is cooled and sent to cypress wood fermentation tanks where one of five different yeast strains is added. “Yeast is a living organism and needs a certain temperature and environment,” Ashley says. “So it is critical to hit the right temperature and concentration of cereal grain and water.” The fermentation by-products are known as thick and thin stillage. The distillery puts the thin fluid—which is very acidic—back into the fermentation tanks to adjust the pH. Over the next four days, the mash will ferment (becoming distiller’s beer) to about 8% to 10% alcohol content. The mash is then run through a column still where it cascades down over plates. While the mash travels down, the still steam percolates through the perforated copper plates and carries the vaporized alcohol to the top of the still. The vapor leaves the still and enters a cold-water heat exchanger. The steam condenses back into very clear and concentrated alcohol at approximately 132 proof. The alcohol enters a doubler that increases the concentration to approximately 140 proof by separating and removing some of the remaining water. Demineralized water is then manually added to the distillate reducing it to 120 proof. The distillate is then poured into charred oak barrels where it will remain for the next five to 20 years, depending on the final product.

Benefits of a newer DCS

“The APACS+ controller’s configuration was transferred to the PCS 7 controllers using a migration tool from Siemens,” Keiser says. “This migration tool helped Four Roses speed up the transition to get online using the more modern controller. This tool also eliminates manual steps, giving a more accurate configuration transfer.”

According to Ashley, the greatest benefit from the DCS upgrade is that the programming is much more user-friendly when it comes to finding data, making changes, or adding and modifying screens. Since he says he is not a programmer, this has been particularly helpful. “I can say that we need a meter on this, or need to graph this, or go in and take a look at the history of these specific items,” he says. “This allows us to fine tune our quality and increase our production. It has also helped us keep our standards at the necessary level. Everything is there: just point and click. Put in your variables and you are off and running. The trending capabilities of the PCS 7 are much more advanced than the APACS+. It is easy for me to dial into the system from home and question why did this happen or how did it happen?”

With the amount of time logged on the new system growing every day, Ashley has been satisfied with his experience. He reflects, “The system worked perfectly before and it works perfectly now. But today, we have the latest and greatest supported software. I don’t anticipate that changing.”

Ken Keiser is PCS7 migration manager for Siemens Industry.


Upgrades of control systems often begin with the HMI, as discussed in this article. This is for a number of reasons:

  • Components used in HMIs (hard disk drives, displays, keyboards, etc.) have the shortest lifespan due to the mechanical nature of many components;
  • Components used in the core processors, field wiring, and I/O have a longer lifespan and generally need the least functional improvements;
  • Many types of functionality are included in the HMI layers, so improving these allows for the most types of upgrades;
  • Adding connectivity to other plant networks and systems (enterprise systems, historians, cyber security protective devices, etc.) is often done through HMI layers; and
  • More sophisticated graphics, alarms, and worker interfaces happen at the HMI layer, so improvements are highly visible to operators.

Read more about migrations and upgrades at .

Control system lifespan: How long is long enough?

Securing legacy control systems

Upgrading control: Migration or evolution?