Hot Oil Oxidation Damages Process Equipment
A few years ago, thermal oil oxidation became a problem for the Abergavenny Fine Food Co., in Blaenau Gwent, South Wales, U.K., when it fouled the plant’s process equipment and increased fluid acidity. Oxidation occurs when an oil temperature greater than 149°F (65°C) meets air in the same space, starting a chemical process from the reaction with oxygen.
The Abergavenny header tank was in excess of 212°F (100°C) and had no nitrogen-blanketing system to protect the overheated oil from the air above it.
Thermal oil “was frequently damaging oil circulation pumps,” says Paul Sanders, Abergavenny’s site engineering manager, explaining that the thermal oil indirectly heats fryer oil for the company’s breaded party-foods line.
Seeking a solution, Abergavenny contacted Global Heat Transfer Ltd., Staffordshire, U.K. Engineers found a buildup of carbon around the piping because the oil had not been tested or maintained for a number of years, according to Sanders. “The carbon was coming loose and damaging the seals in the circulation pump,” he says.
Global Heat Transfer drained, flushed, cleaned and refilled the system, then set up monthly oil testing and analysis to comply with the Dangerous Substances and Explosive Atmospheres Regulations 2002, which requires employers to control the risks to safety from fire and explosions.
Now, “when we carry out our monthly analysis, we can pick up an issue before it starts to cause problems,” Sanders says. “We can monitor the carbon content and pick up any excess buildup of carbon, as well as the acid levels, which can cause corrosion if they go over a certain level.
“We can also keep an eye on the flashpoint as well, which was very low in this case. When I joined the company, the oil had not been analyzed or changed for seven years prior to Global Heat Transfer getting involved. By that time, the damage had been done from the carbon buildup in the pipework, tubes and boiler.”
Abergavenny, operates from a 40,000 ft² facility producing snack foods, ready meals, dairy and desserts. The plant has seen boiler efficiency improve significantly, Sanders says, and there has been a 50 percent drop in heatup time.