Putting the pressure on coal

The Western Research Institute began its coal-to-liquids research 13 years ago when MTBE (Methyl tert-butyl ether), an additive in gasoline, was discovered to be causing contamination in ground water from leaky underground storage tanks at gasoline stations, and was going to be replaced with an alcohol made from corn.

“Our thinking at that time was, if we could make alcohol from coal instead of corn, we should be able to put coal in the gas tanks and save corn for food,” Vijay Sethi, Ph.D., Senior Vice President of Energy Production and Generation of Western Research Institute (WRI), said. The WRI has been developing processes to convert coal/biomass/natural gas to syngas for ultimate synthesis into alcohol and other fuels and chemicals.

DKRW Advanced Energy is working toward raising money to build a coal-to-liquid plant near Elk Mountain and to gain a better understanding of the coal-to-gas and coal-to-liquid process, the Sun met with Sethi to discuss WRI’s research.

Sethi said WRI has been studying the coal-to-liquid process for the last 13 years, and while he is not qualified to comment on DKRW’s project, he could talk about the technology of generic coal gasification.

Sethi explained in order to turn coal into a liquid in one form or another, hydrogen has to be added. The hydrogen comes from water, since water is two parts hydrogen and one part oxygen. The process can be quite complex, Sethi said, using the right amount of pressure and heat for the conversion.

This can be accomplished in several ways, Sethi said. Hydrogen can be added to coal slurry (a mixture of crushed coal and water) under high pressure and temperature in the presence of a catalyst, which is called direct liquefaction.

Gasification is an indirect method of converting coal to liquid. The carbon is converted to syngas, which is a mixture of carbon monoxide and hydrogen. Syngas is then processed through a catalyst to synthesize fuels and chemicals. The gasification method creates methanol, diesel, gas, alcohol or chemicals, depending on what type of catalyst is used.

Technology components needed for a coal-to-liquids plant include a gasifier which makes syngas. The syngas then needs to be cleaned, which requires the gas to be cooled and the sulfur and other contaminants to be removed from the gas, to avoid poisoning the catalyst later in the process.

Sethi said there are several different technologies for gasifying and he mentioned a few companies that have their own gasifiers, including GE and Shell.

In DKRW’s case, a GE gasifier is being used according to documentation provided by DKRW’s chairman, Bob Kelley, in early 2012.

Sethi said that from their website he understands that DKRW is using Exxon’s technology for making gasoline. DKRW will make gasoline and collect CO2 during the process. CO2 will be piped to the oil patch to be used for enhanced oil recovery.

Sethi said for people to understand what the plant may look like when completed, Sinclair Refinery would be a very close comparison, but he believes that DKRW’s plant may be larger.

WRI has been studying different technologies for gasification on a smaller scale, but does not have an integrated plant that goes through the whole process of converting coal into a liquid. They have a small gasifier and a larger gasifier on the premises. WRI also has small modules used to clean the gas. They have a facility at a smaller scale where they can put syngas into a reactor and make liquid, including methanol, alcohol and gasoline.

WRI also has a two-barrel-per-day plant which can convert a portion of the syngas produced by a 10-tons-per- day coal gasifier into two barrels of liquid product. Sethi said their plant is about 1/10000 the size of the plant to be built by DKRW.

It takes time to develop technology for projects the size of DKRW’s plant, Sethi said.

“From concept to plant, 10 to 15 years is quite common.”