Small changes in the use of open flames, or flares, to burn off pressurized gases at oil refineries and chemical plants could help improve Houston’s air quality, a new study suggests.
The Texas Commission on Environmental Quality’s study, which was released Tuesday, indicates that fire-belching flares could destroy harmful gases with a higher rate of efficiency if operated in a different way.
Stacks are designed to be relatively smokeless through the use of steam — so the sight of leaping flames and billowing smoke from plants has unnerved Houstonians for decades. But the study suggests that a visible flame is important in routine flaring, not just in emergencies.
“When you see a fireball, things are burning,” said Susana Hildebrand, TCEQ’s chief engineer. “That’s what you want.”
The TCEQ ordered the $2.2 million study from the University of Texas at Austin after finding higher emissions than expected from flares at several plants. It is the first look at how they destroy smog-forming compounds in nearly 30 years, the agency said.
Flares are an emergency mechanism used to burn off pressurized gases. Pilot lights at the top of the stacks ignite the gases to prevent them from wafting into nearby neighborhoods.
For years, regulators have made smog-fighting plans with the assumption that flares destroyed at least 98 percent of the gases.
But the flare in the TCEQ study burned less than half of the gases when steam was used to reduce visibility of the flame. Without steam, the flare had a visible orange-yellow flame that destroyed 99.9 percent of the gases.
“You can easily use too much steam,” said David Brymer, TCEQ’s director of air quality. “The key is to operate within an optimal window of efficiency.”
Jay Olaguer, director of air quality at the Houston Advanced Research Center, which was not involved in the study, said the findings will be “extremely important” in the next round of plans for reducing the region’s smog, or ozone.
‘Usher in a new day’
Harris County, which is known as one of nation’s smoggiest places, accounts for 21 percent of the 1,519 registered flares in Texas.
The nitrogen oxides and volatile organic compounds emitted from smokestacks, as well as tailpipes, mix with sunlight to form ozone, a colorless gas that can cause lung damage.
Some environmentalists said the study puts the TCEQ on solid ground to require changes in the way flares are used – if at all, because of new technologies – for non-emergency emissions.
“It should usher in a new day,” said Matthew Tejada, executive director of Air Alliance Houston. “These are emissions that are always there, day in and day out, even in little amounts. But when you have hundreds of these sources, they add up.”
Hildebrand said TCEQ will use the study’s findings to educate industry about how to operate flares in the most efficient manner. She also said they may be used in the permitting process but did not hint at any new or revised rules for flaring.
Marise Lada Textor, of the 125-member East Harris County Manufacturers Association, said the industry group was in favor of the study and believed it was well-planned and carefully managed, but was not ready to comment on the findings.