Canandaigua Wine Co. retrofitted a 37-year-old distillation unit at its Mission Bell Winery near Madera, Calif., with a Fisher-Rosemount PlantWeb field-based control system, obviating an estimated $3 to $4 million cost to recondition a distillery at another plant.

The renovated distillery produces 191/192-proof alcohol for Canandaigua's fortified wines and liqueurs, and is capable of producing the neutral-tasting alcohol for Canandaigua's top-quality brandies as well. This allows production of top-quality alcohol to be switched from a nearly dissolved all-copper still at another winery, saving the cost of reconditioning that still and providing a quick payback for the controls upgrade.

Built in 1962, the 2000 proof-gallon/hour stainless-steel distillation unit at Mission Bell had ceased to consistently produce 191/ 192-proof neutral spirits of the taste required. Output had to be trucked to another winery for redistillation. Visual and gamma-scan inspection proved condenser and plates essentially sound. "All evidence pointed to controls quality alone as the culprit in the unit's erratic performance," says Robert Calvin, Canan-daigua's West Coast director of engineering. Canadaigua's Madera winery is third-largest in the world, as measured by crush capacity and cases per year. Brands include Almaden, Inglenook and Taylor.

The winery's distillation plant was built to process a feedstock consisting of fermented sugars (4 to 7 percent alcohol) mainly from the skins and residue of grape processing, off-spec product and sediment from fermentation tanks. The still consists of a short preheating column with two sieve plates, a 125-ft. main column with 62 plates and a second short column to strip aldehydes.

A team composed of engineering, operations and maintenance people evaluated new control options. The team favored a distributed control system (DCS) over a PLC/HMI system because the DCS could offer pre-engineered control and alarm strategies, easy graphic configuration, a global database, Foundation Fieldbus and Hart communications, and the potential for applying advanced controls such as fuzzy logic and neural networks. The team selected Fisher Rosemount's PlantWeb system, which offers conventional DCS capabilities in a compact package incorporating distributed intelligence and rich data collection plus remote diagnostic, calibration and maintenance capabilities.

At the heart of the system is a scalable DeltaV control system consisting of one set of redundant controllers and power supplies, three Foundation fieldbus H1 modules, four Hart I/O modules, two PC workstations and an Ethernet link between controller and workstations.

A 6-ft. by 8-ft. prefab metal building houses the new control room. "Fieldbus was selected as the primary communications protocol to minimize wiring, assure the highest speed and the least drift, and enable diagnostics and calibration from the workstations," says Calvin. Hart devices were chosen only where fieldbus versions were unavailable.

Control logic has not yet been distributed to the fieldbus devices. "Each smart fieldbus device has the ability to run a PID loop in the field," Calvin observes. "It can also be used as a regular instrument. We chose to use the regular instrument and not actually push the control function from the controller into the instrument itself. So we're not using all of the system capabilities at this point in time," although he expects to evolve toward fieldbus control.

Engineered and installed by Doyen & Associates (Bakersfield, Calif.), the system currently employs a traditional strategy based on temperatures, pressures, flows and levels. Cascaded loops and feedforward signals were added to better regulate feedstock, which varies with input, solids and alcohol content. Fisher-Rosemount systems integrators APC-Rust Integration and Caltrol provided configuration and startup in mid-1999.

The new instrumentation provides a wealth of information, says Calvin. Example: Temperatures at 19 plates in the main column are now monitored by fieldbus instruments, generating a temperature profile which informs the operator about the amount and distribution of alcohol, fusel oil (amyl alcohols) and singlings within the column.

Fisher-Rosemount Systems, 8301 Cameron Road, Austin, TX 78754. Tel.: (512) 835-2190.