When a 30-year old regenerative air heater installed on a fired heater in one of Canada’s principal oil refineries was in need of replacement, the plant operators required an experienced engineering company who could do the work with the minimum change to the existing infrastructure and as little disruption and lost time as possible.
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Challenge
Operated by Imperial Oil, the Sarnia, Ontario manufacturing site began operating in 1897 and today is part of the most integrated petrochemicals manufacturing and research facility in Canada. The Sarnia Chemical Plant produces a wide range of petrochemical products, including polyethylene, solvents, higher olefins, and aromatics using refinery and external feedstocks. These products are subsequently used to manufacture many of the products that people use around the world every day.
In 2011 the plant personnel decided that one of its rotary regenerative air heaters, installed in 1983, was in very poor condition and should be replaced. However, while they wanted to bring performance up to state-of-the-art levels of efficiency and reliability, they also needed to minimize the impact on the rest of the plant and keep the downtime as short as possible.
Solution
We examined mechanical details and the current operating conditions for the old air heater and proposed the installation of a completely new, custom-engineered horizontal air heater that would precisely match the existing mechanical interfaces, including the duct flanges and base support plates.
While Howden rotary air heaters normally have a central drive, for Sarnia we fitted a peripheral drive to match the original configuration.
The air heater was pre-assembled in our factory and transported securely shrink-wrapped, at the request of the customer, to prevent damage in transit. Once on site, the installation work was a straightforward two-phase project. Firstly, the baskets and rotor seals were installed in the air heater, then the complete unit was installed and coupled up to the existing foundations and ductwork.
nternally, however, the air heater drew on many of our state-of-the-art innovations. For example, we used our specially-designed simulation software to model the operating conditions in the refinery and recommend the ideal heater element profiles for the thermal and pressure drop required.
In the hot and intermediate layers we used HS20 elements, to give maximum efficiency in the gas-burning system, and we installed HC12 in the cold layer for their exceptional cleanability.
Within a few months of Howden replacing the unit, the plant personnel evaluated the new air heater very positively, reporting significant improvements in furnace operation and the performance of both the forced draft fan and the induced draft fan.
Howden has been at the forefront of rotary regenerative air heater technology for over 80 years. Our unique element profiles and coatings, SurePack Elements™, Enerjet™ cleaning systems and choice of sealing systems enable us to engineer the most efficient, reliable and long running air heaters available today.