CH-85-12-2 -- The Design Concept and Demonstrated Economic Performance of a Cogeneration System At California Institute of Technology’s Central Heating and Cooling Plant PDF

In 1973, the California Institute of Technology undertook an energy conservation-program that reduced the cooling requirement placed on their central heating and cooling plant by the university campus. The use of the steam driven centrifigal chiller was therefore severely curtailed. Concurrent reduction in heating requirements allowed the operating steam pressure in the campus heating loop to be reduced to 345 KPa (50 PSIG). Since the boilers were designed to produce 2068 KPa (300 PSIG) steam for the steam-driven centrifigal chiller and this machine wasn't required very often, it became apparent that an excellent application for a cogeneration system was at hand. A feasibility study recommended a 1000 KW cogeneration system using a radial inflow, back-pressured steam turbine. This noncondensing turbine provides 345 KPa (50 PSIG) steam for the existing campus demand and has proved to be cost effective. Caltech is currently implementing the second phase of this project by adding a combustion turbine that will be nominally rated at around 4 MW. The aggregate rate of return for the facility is expected to be 38.5%.