Heat recovered from the G3516H generator engine is not released into the air as waste, but instead is captured and used to produce hot water, thereby reducing the costly use of boilers and fuel. Waste heat from the engine is utilized in both high temperature and low temperature loops. The high temperature loop, which is in the 190 °F range, is injected directly into the boiler supply that provides hot water for the whole facility.
The low temp loop is used for preheating reverse osmosis water that is utilized in humidification and boiler makeup water through a heat exchanger. The low temp water is utilized in two air handlers that preheat the air before a glycol system completes the process. Utilizing the waste heat cuts in half the amount of energy required to operate four water boilers.
“The low temp loop is just the icing on the cake,” said mechanical power engineer James Cole. “Waste heat from the generator also increases the efficiency of the steam boilers. Altogether, the combined efficiency realized from the Toromont cogeneration plant is in the high 80s,” Cole said.
The G3516H generator set and switchgear is set is housed in an enclosed area of the hospital. The Cat Switchgear is designed for utility paralleling with islanding capability. It controls and monitors the entire CHP system and includes both generator and utility protection. To meet environmental standards, a Selective Catalytic Reduction (SCR) system placed on the roof of the enclosure reduces NOx emissions from 70 to 80 parts per million down to 30 parts per million. A 100-foot stack sends the exhaust past the roofline of the four-story hospital.
“We’re meeting all Ontario Ministry of the Environment requirements with regard to emissions to the atmosphere and noise abatement,” Korol says.
Toromont ensures high uptime
In order to maximize savings, the generator set needs to run 24-hours a day. Currently, uptime is a reliable 95 per cent, with only periodic shutdowns for planned maintenance. Hospital building system operators monitor the cogeneration enclosure two to three times during each 12-hour shift and take critical readings that have been recommended by Toromont Power Systems. “We monitor the operation, and look for changes,” Korol says. “We have cameras set up to monitor inside the cogen enclosure,” Korol says. “It’s a confidence builder for us and a good way to keep an eye on this piece of equipment.”
Since the Caterpillar G3516H was put into service, the hospital’s building system operators have become well versed at operating the generator set.
“Toromont’s presence has proven to be dependable,” Korol says. “We call them anytime day or night and there’s always somebody here within an hour or so, so we have a good on-call support system to help us resolve any operating issues.” Having a maintenance and repair contract is critical because it enables TBRHSC to forecast how much they will need to spend over the next 10 years maintaining the cogen system, so they can budget accordingly.
“Toromont won that competitive process, and I think a big part of it is that Caterpillar makes an established product with a track record of reliability that is as good or better than anybody else,” Korol says. “Toromont has a major service presence here in Northern Ontario, and that aligns well with our requirements.”