The Industry’s Inexact Science

There was no method to Sam McTier’s madness. This, he admits. When it came to ridding water from a large propane container, the industry veteran tried just about everything.

He heated containers until they were too hot to touch and the opening began steaming “like a son of a gun.” When water still was visible, he tried to siphon it out by sucking on a tube and encountering “the dirtiest crud I’ve ever tasted in my whole life – and I thought I was going to die.” Then imagine McTier trying to turn the containers over to empty the water and shining a flashlight into the darkness to see if any water remained.

“The only solution,” the 81-year-old McTier recalls of trying to prevent water from freezing regulators, “was to load the propane up with methanol.”

McTier, who began his career with United Petroleum Gas, spent 22 years with RegO and later founded McTier Supply Co., transported a 55-gallon drum of methanol in the trunk of his Plymouth and used it to treat customers’ regulator freeze-ups. Through trial and error, he developed a formula of using one pint of methanol per 100 gallons of propane.

Methanol to be added

“I’m not a great expert, but I had a lot of success and luck in solving this problem,” he says, chuckling. “It wasn’t because I knew what I was doing.”

Presence of water in propane

“Propane has been used since the early 20th century, and water in the fuel has been a problem since then,” says Rodney L. Osborne, associate manager of Applied Energy Systems at Battelle. “A lot of homemade recipes were used throughout the industry. Like any early recipe, if it works you keep using it.”

Having concerns about the use of methanol to control water freezing, the National Propane Gas Association and the Propane Education & Research Council (PERC) asked, from a scientific standpoint, “How much methanol should be used?” That question was the basis for a study by Battelle, funded by PERC as part of its ongoing fuel quality research.

“We tried to put some science to the rules of thumb and give some further guidance to propane marketers,” says Osborne, who presented the study’s findings during a technology forum last September in Austin, Texas.

Guide for use of methanol in propane

Water that remains in a container can come from numerous sources, including the refinery or processing plant, the pipeline system or inadequate drying after hydrostatic testing by the container manufacturer, and can dissolve into propane. This creates the potential for two types of problems: If water drops out of solution due to a temperature decrease, a water-rich layer can form at the container bottom; this can lead to corrosion and fuel quality issues. The second problem is the potential for regulator freeze-ups, since the propane vapor can contain water.

“You could prevent the water in the first place, but this is extremely difficult,” Osborne says, “or you can use a de-icing agent, such as an antifreeze like methanol. The main goal is to prevent freeze-ups in regulators.”

Adapting the recipes

Methanol, a simple alcohol, has been a constant in the propane industry to prevent freeze-ups. “Recipes” such as McTier’s and those detailed in RegO and Fisher service handbooks have provided guidelines on the amount of methanol retailers should use. Battelle’s study looked at whether any of these recipes were the result of testing and whether any improvements could be made to the guidelines.

Conclusions

“There were some early experiments, but mostly it just came down to field experience,” Osborne says. “We then took a look at developing a new guideline, using the data we could find and some assumptions.”

One of the main issues with methanol has been the unknown history of its usage along the propane chain. There remains no clear way of knowing how much methanol, if any, has been added to propane. On a cold morning, someone downstream may feel inclined to use methanol as a precaution, even if it’s already been added. And excessive amounts have the potential to cause operational problems with newer applications.

“That’s the problem with a product like propane,” Osborne says. “It’s a batch service. Once it goes into a container for transport or storage, it becomes a batch. And at that point, someone can add a shot of methanol to it. There’s the potential for an awful lot of methanol.”

Consultant’s conclusions

Industry veteran and consultant Bob Myers oversaw the Battelle study and cites two conclusions: He was surprised that little research had been done on the propane-methanol-water mixture at temperature and pressure ranges of interest to retailers; the other is the study’s intent on developing guidelines for the industry to follow.

If conditions apply (see graph), researchers recommend an anhydrous methanol addition rate of 600 parts per million, which is equivalent to 4.9 liquid ounces of methanol per 100 gallons of propane. Equivalent rates using other units of measure are shown in the chart.

“The outcome and objective of the whole report was to have a simple chart that a guy at the bulk plant, on a cold December morning, could look at and wonder how much methanol he should put in,” Myers says. “It certainly would be a great service to the industry.”

Now, Battelle is taking its research to another level. PERC approved $213,500 in December for Battelle to design a portable handheld water detector for propane. It would replace existing methods, none of which are sufficiently accurate, free from interferences and usable in the field, according to Battelle.

“That really is the next step,” Osborne says of developing the instrument. “Otherwise, we’re just continuing the guessing game.”