Case Study
Royal Victoria Regional Health Centre – Barrie, ON
About the Project
Category: Construction
Scenario:
The hospital had a 400 TON chiller and an 800 TON chiller coupled with three 400 TON cell centrifugal cooling towers. All three cooling towers shared 16’” supply and return headers. The cooling towers were mounted on the roof, with chillers and pumps next to the building. The cooling towers require replacement due to high maintenance costs, make up water, high chemical treatment usage and hot / cold water basin leaks.
Scope:
With a conventional cooling tower retrofit design the anticipated installed cost was over the budget in part due to multiple piping inlets, outlets, 12 inch diameter piping @ 100 feet of length, heat tracing, supports and multiple isolation valves. Our scope of the cooling tower retrofit project was to reduce the installed costs and provide a condenser water cooling solution that can cool 95F water to 85F with a 76F wet bulb temperature. The cooling tower should handle 1200GPM, 2400GPM and 3600GPM flows when both 400TON and 800TON chillers run at the peak load. The operating weight of the cooling tower needed to be equal or less than 40,000lbs in order to retrofit the cooling tower without making any major structural changes to the roof.
The Design:
The two chillers in the original building were not equal in size, one being a 400 TON unit, while the other is an 800 TON unit. The hospital was concerned that with adding a two cooling tower system, the towers would be oversized and inefficient once the smaller chiller was in operation. Working with Tower Tech Inc Cooling Towers, Longhill Energy provided one Tower Tech TTXL-121975, twelve- fan modular unit which not only met the required thermal performance and weight restrictions, it also provided an impressive 3:1 turndown on the condenser water flow, allowing for a single 1200TON Cooling tower foot print to be used for the 400TON or the 800TON chiller or running both in combination i.e. 1200TON application.
The tower’s twelve bottom-mounted direct-drive fans provide a built-in redundant system and offer the flexibility to be either controlled individually or collectively via the VFD system. In addition, the patented flow through basin helps to reduce the risk of Legionella by making it more difficult for bacteria to breed and reducing the amount of drift emissions. Tower Tech drift loss factor is 0.0004% of the water flow compared to 0.005% from conventional cooling towers while drift eliminators reduce the mist or drift being transmitted to humans by up to 90% over what’s currently typically installed.
The inherent mechanical redundancy built in to a Tower Tech Modular Cooling Tower means that our larger cooling tower modules continue to provide sufficient cooling even if one or two motors are off-line.
Installation:
Tower Tech modular ultra-efficient cooling towers come down the highway in one piece and completely ready to go. They come factory assembled, with only four legs and a sump box to connect, yielding a total install time per module of less than one hour. This leads to a faster overall installation as compared to the competition in terms of total man hours and crane time.
Advantage:
The Tower has a perimeter wall basin which hold less water than a conventional cooling tower area basin. The tower needs less chemicals to treat the water in the basin plus the basin is isolated from direct sunlight which helps to prevent algae growth.
With the use of 12 direct drive fans connected via a variable frequency drive system, the total kWh consumed per year was lowered compared to the existing system and the hospital became eligible for a saveONenergy incentive.
With 12 fans available, if one fan fails the cooling tower loses only 8% of motor power and even less loss of cooling because the VFD ramps up the rest of the fan motors at higher speed to compensate.
Since smaller motors are placed on the bottom of the cooling tower, no cranes will be required for motor replacements in the future.
Praise from the client:
“ALL TOLD, THIS KIND OF TECHNOLOGY IS SOMETHING THAT OTHER HEALTHCARE FACILITIES SHOULD ENTERTAIN IF THEY ARE LOOKING AT TOWER REPLACEMENTS.”
– Rob Purdy, Director of RVH
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