Queenâ€™s uses steam to heat the campus. Steam is an energy-efficient technology compared to other heating methods when used on a large scale. The Central Heating Plant is located on King Street, across from the Kingston General Hospital, and is run by Queenâ€™s Physical Plant Services. The plant puts out 20,000 pounds of steam per hour.
- The steam plant uses over 20,000,000 liters of oil a year
- The plant delivers over 700,000,000 pounds of steam per year
- The system has an efficiency close to 90 percent
Currently, steam is produced by burning bunker oil. The steam plant has recently moved to a cogeneration model as well, generating its own electricity for the campus at peak times of the year. Waste heat from the generation process is used to create steam, bypassing the boilers. Since the steam infrastructure is already in place â€” there are miles and miles of tunnels under Kingston â€” cogeneration saves the University money and is environmentally friendly.
The current heating plant was built in 1923 and upgraded in the â€™60s. Some of the tunnels date back to 1904 and are up to a mile long at a stretch. They run under the University and, for over 50 years, the plant also served both the womenâ€™s prison and the Kingston Federal Penitentiary.
A closed loop
Steam from the plant enters Beamish-Munro Hall in front of the biowall, at a pressure of 400 kPa gauge. The heavily-insulated pipes are visible through three separate cutouts in the floor before they disappear into the mechanical room, located beside the atrium, where the steam pressure is reduced to 70 kPa gauge.
From there, the pipes feed into the IL Centreâ€™s mechanical penthouse and into Goodwin Hall. Steam pressure and condensate returns are monitored by the Live Building systems in real-time. And from the mechanical room, steam is fed up to the penthouse. There, it goes into the air handling units and to the heat exchanger that generates hot water for localized heating.
Steam heating is a closed-loop system. In the heating coils the steam condenses to water, in the process giving up its enthalpy of evaporation. The water, called condensate, is collected and piped back to the central heating plant (the pipe at the bottom of the image is the condensate return). Condensate is well worth collecting and reusing in the boilers, because:
- it is hot, thus reducing the amount of fuel needed;
- it is distilled and therefore demineralised; and
- it has very low levels of dissolved gases
Condensate is also collected from the steam distribution pipes. Even though they are well insulated, inevitable heat loss causes some of the steam to condense. This condensate, if not removed from the pipes, would eventually build up to a level where it would impair efficiency and cause other serious problems like water hammer, which can cause physical damage to the pipes and system.
Minerals are bad for boilers because they cause scale and sludge. Dissolved gasses, particularly oxygen, are corrosive. To prevent this, water used in the steam system is treated to remove minerals before