Reports from the field: survey at a central utility plant

I recently visited a large central utility plant that once powered a data center. With a 3,000 ton chiller plant and 9,600 MBH boiler plant, the system is currently running at a much smaller part load condition than in previous years; but, it still maintains a large load capacity. Even with the reduced load, the facility has an intricate system design, which can be overwhelming to a young engineer. Luckily, I had experienced engineers to guide me through the design.

The utility plant in total has four cooling towers, three 1,000 ton chillers, two 4,800 MBH boilers, a free-cooling heat exchanger, and 3 back-up generators. The maintenance effort and coordination of these systems is incredible. The ability of the plant controls system to actively respond to plant loading and outdoor conditions is really amazing. While the sound engineering design of a large plant is important, a crucial part of a large facility like this is the maintenance plan to keep the equipment running effectively.

One example of the maintenance plan design is the chiller assembly by the use of a marine water box. The maintenance procedure on a chiller with a marine water box is much faster. With the marine water box, the water enters the side of the chiller into a split box, then enters the chiller. For maintenance, this means technicians only have to open the back cover of the marine box to clean the chiller tubes. There is no need to disconnect any piping. Without the marine water box, the maintenance technicians would have to disconnect the piping from the chiller, then the back cover to get access to the tubes. Depending upon the size of the chiller, additional features such as hinges and davit arms can be included to improve serviceability as the weight of the box cover can be significant. Design considerations such as this make operation and maintenance easier for the owner, providing value. I hope to implement this as well as other design features learned at this central utility plant.


Chiller with a marine water box


Chiller without a marine water box

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