Process upgrades: from slight changes to system revamps

By Nicholas Zeman | December 21, 2009
A considerable amount of material has been released by companies lately regarding equipment upgrades and process optimization technologies targeted at the biodiesel industry. Cost and yield rewards have to be weighed against the burdens of additional capital costs when plant managers contemplate upgrades. Additional testing and lab equipment, automated controls, oil and grease pretreatment systems, glycerin recovery and distillation columns comprise a short list of the products and services that plants could incorporate into their production schemes.

While there are opportunities for improvement, getting the design of a plant right the first time-or at the beginning-is still essential. "Most of the upgrades that we do involve additional equipment for oil cleanup before transesterification," said Derek Masterson of process technology provider Crown Iron Works, headquartered in Minneapolis.

It's much easier to upgrade the parts of the plant that are self-contained, that don't have fluids traveling back and forth between them. That's why improvements are made at the front and back ends-feedstock purification, fuel polishing and glycerin recovery, to name a few. "Often a lot of plants that need upgrades just aren't designed very well to begin with," Masterson said. "We consider energy efficiency and yield in the initial plant design, so as a technology service provider we don't do a lot of upgrades in these areas. So much of a biodiesel plant is integrated that it would basically take redoing the entire plant rather than doing improvements on certain components."

Canada's TWD Technologies Ltd. recently received a Consulting Engineers of Ontario award for its work upgrading Sanimax's 20 MMgy biodiesel production facility in DeForest, Wis. "We were working with a start-up plant that had major reliability and operational issues," said TWD Technologies partner Scott Wilson. "We needed to come up with a plan to help the plant achieve operating targets and efficiently use capital dollars." The upgrades implemented by the plant increased biodiesel production yield by 17 percent.

For the Sanimax project, TWD Technologies-with offices in Burlington and Sarnia, Ontario, and Edmonton, Alberta-focused on improvements to the plant's vacuum system. Power is utilized by several process components in the production of biodiesel, such as the methanol stripping and methyl ester dehydration steps. In some processes, small amounts of excess water are removed from the feedstock oil or the washed biodiesel through vacuum evaporation. Vacuum and vapor loads are dictated by the facility's initial design; and a reliable vacuum system meeting these requirements is critical to profitability.

Maintaining controlled vacuum pressure is vital to the operation of many pieces of equipment. "A plant's vacuum system is very important to polishing of the fuel on the back end," said Jennifer Cooper with TWD Technologies. "By improving the vacuum system we were able to increase the yield-providing more sellable biodiesel."

TWD Technologies developed a complex computer simulation of the refinery to optimize its process operating parameters. Cooper and Wilson explained that biodiesel is still a very new industry and commercial "off-the-shelf" simulations are not readily available, therefore the company made extensive customization to existing software using inputs from plant operations. "Process simulation validates flows, temperatures and pressure of the operating conditions, which is key to equipment design," Cooper said. "It helps draw out different streams in the composition."

There are small changes that one can do with controls sometimes, Masterson said. "Sometimes a plant can get a 1 percent yield increase just by changing the temperature."

A lot of attention has been paid to filtration equipment regarding more stringent ASTM regulations and the release of products from Schroeder Biofuels, Dover Chemical and others, so biodiesel facilities can ensure and sell a high-quality product. Again, filtration is usually a part of original plant design, and even ADM offers its patent with no royalty fee, so this technology is nothing new, Masterson said.

"Inquiries about glycerin recovery come and go, when the price of refined glycerin is high everybody wants glycerin purification and when the market's bad you don't hear anything," Masterson told Biodiesel Magazine. "We have offered distillation. It's very expensive but certainly one solution. If there is a quality problem then full distillation may be required at some point."

Something as simple as the addition of a mass flow meter to monitor throughput conditions on certain pieces of equipment might help save time and money regarding preventative maintenance. Often, however, additional automation and process controls are hard to incorporate into a plant after the initial design. "We put in a highly automated system to begin with," Masterson said. "Putting in a lot of extra controls and software could be as expensive as the original equipment, and that is not usually an investment people are willing to make. As a technology service provider, we've sold some brand new biodiesel plants outside of the U.S. That's a much larger base of inquiry."
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