Three engineering students, overseen by Chemical Engineering professor Douglas Cooper, began a research study over the summer aimed at helping the UConn power plant attain greater performance efficiencies. The team seeks to fine-tune plant operation with the goal of reducing the consumption of natural gas and fresh water while still meeting the electrical, heating and cooling requirements of its customer, the UConn campus.
The combined-cycle cogeneration plant supplies electricity to the entire campus, from dorms and academic building to administration and service facilities. It also provides steam heating in the winter and chilled water cooling in the summer. Before the highly efficient plant came online in 2006, the University purchased electricity from a utility company that relied upon nuclear reactor and coal combustion plants. Steam was generated on-campus in an old-style boiler house.
The student team includes doctoral candidate Rachelle Howard (Chemical Engineering) and two undergraduate students, Michelle Przybylek (Environmental Engineering) and Melissa Tweedie (Chemical Engineering). They will collaborate with the plant Utilities Manager, Ronald Gaudet, and Power Plant Supervisor, Tim Grady, to:
- Reduce natural gas usage and carbon emissions through improvements in overall plant efficiency;
- Reduce water usage through identification of alternative designs and operational practices; and
- Lengthen equipment life and reduce equipment maintenance costs through decreased cycling.
According to Dr. Cooper, “This effort promotes University President Michael Hogan’s objective of a more environmentally-sustainable campus. It reinforces UConn’s position as a leader in researching, demonstrating and supporting solutions to urgent global challenges.” The in-plant performance study is supported by Thomas Callahan, UConn’s Associate Vice President for Administration & Operations.
Mr. Gaudet explained that a combined cycle power plant burns fuel (natural gas or fuel oil) only once but generates electricity in two ways. At the UConn cogen plant, the fuel is first burned in what are essentially jet engines – three large gas turbines – turning electric generators in the process. The hot exhaust gases exiting each turbine then enter steam boilers, called heat recovery steam generators, to produce both high pressure and low pressure steam. The high pressure steam turns a steam turbine generator to produce yet more electricity, without burning additional fuel.
Ms. Howard’s tasks focus on the control system, testing and documenting new methods for plant performance evaluation and loop tuning where the cogeneration plant operation is the primary focus and beneficiary. A control system is the computer “brain” of the plant. It receives hundreds of temperature, pressure, flow and other sensor signals, and rapidly adjusts valves, pumps, compressors and the like so the plant runs safely and efficiently. Ms. Howard has developed a method for analyzing control signals and improving control system performance without the need to “bump” or deliberately disrupt the plant as required by current industrial practice. To confirm the accuracy of the new method, she double checks her new analysis with Loop-Pro®, commercial software donated to the University by Control Station, Inc.
Ms. Przybylek, who participates in the UConn Honors Program, will perform an overall energy and carbon balance analysis that will form the basis of her senior Honors thesis. Ms. Tweedie will build upon her previous experience with UTC Power to perform an overall water balance analysis. Both will participate in other tasks as needed to the benefit of the plant.
Dr. Lee Langston, professor emeritus of Mechanical Engineering, who was instrumental in convincing the University to build the cogeneration plant, explained that after electricity generation, there is plenty of low-pressure steam left over to heat campus buildings, kitchens and laboratories in the winter. During the warmer months, when heating loads are greatly reduced, the low-pressure steam drives refrigeration compressors to supply chilled water to air conditioning units in campus buildings. The result is that UConn’s new facility is among the most versatile and efficient academic cogeneration plants in the country.
