Production Facilities
The multi-fuel, multi-boiler design of the Central Heating Plant (CHP) makes it an inherently reliable source of heat for the campus. In addition, there are many features and practices that ensure no unscheduled downtime for production. Emergency power, looped and back-up power circuits, distributed digital controls, UPS for controls, system redundancies, steam powered auxiliaries, operator and maintenance training, maintenance philosophies, exceptional design, careful installation, and planning all contribute to the high reliability and availability.
Each year a three day shutdown of the CHP occurs which allows all repairs and tie-ins to be made that would otherwise require large customer impacts. This shutdown begins the day after graduation and 72 hours later, steam is back up in all the buildings.
A major ingredient of steam system reliability is the valving and piping configuration. The steam piping in the plant is configured in a ring header with bifurcating valves and many possibilities of double valving for critical equipment. Only two vendor's steam and feedwater isolation valves are allowed in the plant and all are tested periodically to ensure shutoff characteristics.
Distribution System
The steam distribution system is a looped system with a philosophy of "single unit contingency" and three valve "T's" so that in nearly all cases, peak load can be met with a section of distribution system out of service. Use of high performance, high temperature butterfly valves (steel seated) ensures tight shutoff. Very tight control of design and construction for all distribution work is managed by utilities staff. Our current philosophy of construction was chosen due to its cost effectiveness and long life.
A proactive annual steam manhole inspection program is used to find, fix and track all problems in the system. Full digital mapping and valve vault manuals are used by the distribution coordinator and pipe shop crews. It has been found that keeping the system dry, leak tight, free to move as designed, and within temperature limits will allow for maximum reliability and availability.
District Heating Availability and Reliability
The normal operating criteria for the district heating system is to maintain a minimum steam pressure at the furthest point in the distribution system (35 psig summer and 75 psig in the winter).
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