Heating Distribution
The original steam distribution system was installed in 1889 and was encased in wood. The original lines of the present system were installed in accordance with the District Heating Association Handbook of the time, typically asbestos insulated pipe encased in concrete with an air space. Amazingly, some of these lines are still in service. After many years of trying new concepts, we are back to something similar to what worked in 1922, i.e., concrete encasement.
The present system consists of 13.4 miles of steam line, 12.4 miles of condensate line, and 165 vaults or manholes. The typical installation today is an inverted precast shallow tunnel on grade beam with fiberglass or mineral wool insulation. The average line age for the steam distribution system is: 15 years for large mains, 50 years for small mains and 60 years for laterals. Our mantra is "keep it dry and it will last forever." Our challenges regarding distribution include:
- Maintaining service
- Minimizing road disruption during construction
- Road salt
- Ground water
- Personnel safety
- Asbestos
- High plant export temperatures
Cornell continues to update and renew the steam distribution system. The objectives are to have no leaks, no hot spots, no safety problems and no service interruptions, and still be cost competitive to our customers. The steam system is becoming hard to find: to the lay person (no visible leaks), or even to an infrared camera (no hot spots).
Here are some highlights of our distribution program:
- Standard steam construction is inverted concrete U-shapes on a grade beam
- Steam vaults have two covers and stainless steel ladders
- Steam vaults have large out of vault ventilation ports
- We are refining the use of remotely cast vault components
- Steam and CW share large vaults
- Vault roofs are covered with full membrane roof material to eliminate ground water infiltration
- Trenchless construction is being utilized where necessary
- Tri-annual infrared helicopter fly-overs
- Five year system dynamic computer modeling for long range planning