The system automatically controls the sequential startup and shutdown process, beginning when wood chips or other feedstocks such as pulp-and-paper waste are fed from a large feed hopper into a grinder to be ground down to small particles. The sawdust-sized cellulose then is mixed with acid, heated and fed into reactors. Operators in the control room use 10-to-15 process graphics to visualize each step of the process. Sequential PCS 7 function charts are used to smooth startup and shutdown sequences, providing a visual guide for the steps and associated interlocks.
"There is one master station and one slave station that operators can use to run multiple operations in parallel," Doherty says. "They see real-time data, including flow, pressure, level, temperature and acidity. Throughout the process, sensors automatically send signals from the plant to the PCS 7 controller via Profibus and to the graphics computers via industrial ethernet."
The demonstration plant's reliability and control have substantially improved, probably by more than 50%, compared to operations in New York, notes Fitzpatrick.
"The increased yield is primarily due to the tighter plantwide control provided by the PCS 7 control system and its integration with the electrical and lab systems," he says. "The control system responds to our needs and requirements. It is also certainly flexible enough to deal with the different types of feedstocks."
Data and Diagnostic Benefits
Eventually making their way to an Excel spreadsheet, the data generated by the process are Biofine Renewables' bread and butter. Fitzpatrick must prove to investors and potential clients that the intermediates will help make second-generation biofuels and biochemicals available to the market.
Optimation/Dumont Associates worked extensively to link process data with a custom database and laboratory sample data, allowing operators to complete their material balance calculations throughout the day and determine process yields, says Doherty.
"We have integrated the PCS 7 system with our lab information system," Fitzpatrick notes. "We can get a complete download of process data from PCS 7 and coordinate it with independently generated laboratory analytical data."
That coordination of data is important to Biofine Renewables' investors and potential clients because it identifies areas requiring further investigation and helps tailor experimentation accordingly.
"Sure, you can look at one sheet of data and compare it with another — but to have it coordinated, complete and together, is a nice feature that enables us to more effectively use our resources and minimizes duplication," Fitzpatrick explains. "The PCS 7 system provides data that are systematic, businesslike and understandable. We do not have to cross-reference complex data sets with operations. That is done automatically."
Another control system benefit is the ability to provide Optimation/Dumont Associates with remote access via the Internet to the plant's engineering station. By troubleshooting over the phone and Internet, Doherty estimates he spends 20 minutes diagnosing and solving problems, eliminating the two-hour trip to the demonstration plant.
"We can go online and look at the process, identify the issue and make or suggest changes," Doherty says. "We can respond from home or work any time of the day. In the beginning, they had some mechanical process issues with their equipment. It was not obvious if it was a software issue, a process issue or if something broke. We were able to point them in the right direction to confirm that it was a hardware issue."
The Next Step
Biofine Renewables is considering two potential large-scale projects in the near future, says Fitzpatrick. Now in the planning stages, these would produce heating oil as well as biodiesel fuel and building block chemicals such as levulinic acid.
"We intend to standardize on the Siemens system as we scale up," he adds. "The graphics are intuitive and the trending and alarm functions are very good. The customer service support from Optimation/Dumont has been impressive as well. It is always better in a scale up to have consistency with proven partners and technology."
Rich Chmielewski is marketing manager for Siemens Industry, Inc., Spring House, Pa. E-mail him at firstname.lastname@example.org.