Projects

The University of Houston is experiencing significant growth around campus. One of the issues associated with campus expansion is the ability of the current chilled water, steam, and condensate systems to meet the new capacity requirements. Accordingly, the Central Plant was being upgraded, but the distribution system needed to be analyzed for deficiencies.

The objectives of this study were to complete the following tasks for the chilled water, steam, and condensate distribution systems:

1. Identify limitations in distribution systems.
2. Determine modifications required.
3. Establish when modifications need to be made relative to building work.
4. Estimate cost of modifications.

The chilled water distribution system is currently served by five water cooled chillers, which combined provide 19,000 tons of firm cooling capacity, and seven chilled water pumps. The chilled water model of the current campus distribution shows that about three-fourths of the buildings on campus have a negative available ΔP. SSA’s computer model and analysis of the chilled water distribution showed how to greatly improve the flow of chilled water.  The key upgrade iss the addition of 30” cross connect chilled water lines. These lines extend from new piping at the Central Plant to the existing piping in the tunnel near the Graduate College of Social Work.

The steam system has three boilers with capacities of 45,000 PPH each. The boilers produce saturated steam at 100 psig for distribution. Each building has a pressure regulating valve that reduces the incoming pressure to 15 psig. The pressure regulating valves are on campus designed for 75 psig incoming steam. The current steam distribution system is adequate and has spare capacity for serving future loads.

The condensate return system is comprised of a condensate tank and return pumps at each building that uses steam, and the tunnel piping that transports the condensate back to a condensate storage tank in the Central Plant. As a result of the model, the maximum required discharge pressure for the condensate return system was no more than 5 to 6 psig at all locations on campus. This relatively low discharge pressure indicates that all the condensate pumps on campus should have enough pump head to return the steam condensate back to the Central Plant.

Life of the distribution piping is typically limited by internal and external corrosion and older piping should be evaluated for future life expectancy. SSA recommended that UH implement a nondestructive evaluation plan to establish corrosion rates for the piping systems.