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Tires recycled by MacMillan Bloedel and other companies may have a new future as supplementary fuel for power boilers.
A trial to turn old rubber into tire-derived fuel (TDF) is underway at Port Alberni, using ground-up tires from the recycler who collects much of MB's used tread.
Tires collected from MB by Target Industries in Port Alberni are among those being converted to grindings for test-burning at Pacifica's Alberni Specialties paper mill. The trial is underway almost one year, under an approval from the B.C. Ministry of Environment that expires March 31, 1999.
Trials with TDF as two per cent of total fuel demonstrated no increases in stack emissions of total particulate or metals, improved the burning of lower-quality hog fuel in the boiler, and reduced natural gas consumption.
Pacifica recently applied to B.C. Environment to continue using TDF for up to five per cent of its fuel load at Alberni Specialties - that's about 40 tonnes of TDF mixed with 800 tonnes of hog fuel, per day - through an amendment to its air emissions permit. MB, Target and Pacifica say burning TDF in the mill power boiler is an environmentally-sound and economic solution to many of the challenges of waste tire disposal.
"It's a win for everyone," says Jon Pillsbury of Environmental Services, noting that approval to continue burning TDF at Alberni Specialties would ensure a productive use for MB's waste rubber and provide Pacifica with a relatively clean-burning and energy-efficient supplemental fuel.
Equally important, he says, approving the permit could contribute to disposal solutions for used off-highway and heavy equipment tires. Tires larger than 1400-24 are not collected under B.C.'s tire recycling programs, because so few tire recyclers are able to process them. There's little economic incentive to invest in a new recycling plant when markets for used rubber are less than robust.
MB's Waste Management Standard says all waste tires must be sent to a tire recycling facility, where one is available. Larger tires not collected by recyclers - up to 100 a year, at a typical logging division - continue to be a problem and are often stockpiled. MB's standard also specifies that tires are not to be landfilled or burned on-site, and are not to be used to start fires in wood debris piles at dryland sorts.
So turning tires - especially larger tires - into TDF appeals to MB, Target and Pacifica. It turns out, too, that the Ministry of Environment (MOE) has authority for both Pacifica's air emissions permit AND tire recycling programs in the province.
MOE's Financial Incentives for Recycling Scrap Tires (FIRST) program levies $3 on all new-tire sales in B.C. and uses the funds to provide financial incentives to businesses like Target to help offset the costs of collecting used tires from companies like MB, and to process them for other uses. Initiated in mid-1991, by mid-1996 - the last update at the ministry's website - it had contributed $18 million to tire recycling, and collected the equivalent of 12 million passenger tires. On average it collects 250,000 tires a month.
About 60 per cent of the tires FIRST recovered in 1996 were 'recycled,' and 40 per cent became supplementary fuel. The ratio is reversed in the U.S., where TDF use is more widely established than in B.C. In the U.S., slightly more than 150 million pounds of TDF was consumed by industry as fuel in 1996, from a high of 30 million pounds in industrial boilers to a low of two million pounds at dedicated scrap tire-to-energy facilities.
Tires are burned as supplemental fuel at at least one cement plant in B.C.'s Lower Mainland. TDF already has a history on Vancouver Island. It was test-burned in boilers at MB's former Harmac pulp and paper mill as a possible alternative fuel source during the 1970s energy crisis. TDF's attractions to industry include high BTU at a more economical cost than oil or natural gas, and cleaner emissions than from coal.
"Tires have a chemical composition similar to petroleum products, and burn in a power boiler like petroleum," says Anthony Stock of Target. "The difference is, TDF is more economical to burn than natural gas or bunker fuel."
Other advantages of TDF include reducing tire content in the solid waste stream, and limiting any potential for fire, health and soil contamination from stockpiling scrap tires.
No black cloud
for TDF rubber
There's no black smoke from Alberni Specialties when TDF is burned in mill power boilers. Black smoke from burning tires typically occurs only when there's too little oxygen available to feed an open fire - something that doesn't happen in power boilers.
In fact, TDF is a perfect complement to the No. 4 boiler at Alberni Specialties, says the mill's environmental supervisor, Larry Cross.
The boiler - one of three at the mill, and the only one burning hog fuel - was reconfigured in 1997, when MB owned Alberni Specialties. The $20 million project installed fluidized-bed combustion technology for more efficient burning of dryland sort wood debris and hog fuel, and to reduce both maintenance costs and natural gas consumption.
Along with superiour combustion qualities, fluidized-bed technology is noted for its energy efficiency and reduced air emissions.
"Our people looked at boilers all across North America before ours was upgraded, and we often saw TDF being used elsewhere as a supplementary fuel - and used successfully," Cross says.
The magazine PIMA's Papermaker adds that TDF "presents an ideal fuel source in that its moisture content is low (one to three per cent), thereby reducing the amount of energy required for moisture vaporization. Hog fuel, by comparison, is usually more than 60 per cent water.
TDF's superiour burning and relative affordability make it a perfect complement to the design of the power boiler at Alberni Specialties, and to the low-quality dryland sort hog fuel Pacifica burns there, Cross notes - and testing showed no cause for concern about emissions. TDF at two per cent of total fuel demonstrated no increases in stack emissions of total particulates or metals.
Amending the mill's air emissions permit would allow up to five per cent TDF of the total fuel burned per day in No. 4 boiler.
Cross notes Alberni Specialties has made a number of contributions to improved air quality in the Alberni Valley in recent years, including installing a power boiler precipitator in 1989, and is determined that using TDF will not degrade that performance.
Tires shredded,
metal removed
Target Industries removes much of the metal from the old tires it is shredding in Alberni for TDF. "We chip them to three quarters of an inch, and the majority of the wire is removed," says Anthony Stock, Target's president and a nine-year veteran of tire recycling.
Pacifica wants removal of as much metal as possible because it has no fuel value, says environmental supervisor Larry Cross, and because it would simply end up in the waste sand from the boiler. Emissions from Pacifica's boiler stack are regularly tested for metals.
Target uses magnets to remove the metal from tires when the rubber is shredded. Recovered metal is recycled through Budget Steel in Victoria.
To date, Target has not been recycling MB's larger tires but Stock says he will take some 'very soon.' Target is working on processes to de-bead the tires, 'cut them into chunks' and shred the pieces with smaller tires.
The world of rubber
- Tires have 40 per cent more energy value per kilogram than coal, reports Goodyear Tire, and an energy value equal to oil.
- A pound of tire chips yields approximately 15,000 BTUs, compared to 13,000 BTUs for coal and 4,000 BTUs for hog fuel.
- One passenger tire can provide energy equivalent to almost nine litres of oil.
EnviroLink, 1999
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