WEST BOUNTIFUL — Recent upgrades completed at the Holly Refinery are expected to make flares more efficient and quieter.

Instead of having two principal flares, only the north flare will be used in the refinery's system to let product burn safely when the refining process is upset.

The south flare will be used only when the north flare is being serviced, according to a refinery news release.

Past rumbling during flaring was caused by the injection of steam at the tip of the south flare, but the north flare's steam injection is less noisy, according to refinery officials.

A new gas-plant compressor is designed to reduce flares and the number of outages at the refinery. It is expected to reduce emissions by 340 pounds of nitrogen oxides, 33 pounds of carbon monoxide, 13 pounds of hydrocarbons and 4 pounds of particulate matter per day, the release states.

— Joseph M. Dougherty