"We're working to prove that the conversion from sugar to gasoline is economically feasible." Virent Energy Systems' Brian McWhorter explained how Emerson's DeltaV platform is helping to streamline scale-up from pilot to commercial phase production.Virent was founded in 2002 to commercialize the aqueous phase reforming (APR) process, a technology that generates hydrogen from sugar, which Virent researchers have advanced into its BioForming process, which combines APR with other catalytic technologies to produce renewable liquid fuels, fuel gases and other chemicals.
In early 2006, Virent expanded the BioForming technology to convert plant sugars into hydrocarbon molecules like those produced at petroleum refineries. These hydrocarbon mixtures then can be used directly or blended seamlessly to make conventional liquid fuels. Gasoline was the first liquid fuel Virent produced.
Virent has received significant commercial interest and counts Cargill and Honda among its investors. The company also entered into key strategic industrial collaborations, including with Royal Dutch Shell for the development and commercialization of biogasoline.
"At Virent, work is being done to prove the conversion from sugar to gasoline is economically feasible," explained McWhorter. The process control system includes Emerson's PlantWeb DeltaV/AMS systems with 375 device signal tags (DSTs) and 200 step sequences handling critical reactor operations. "The 200 step sequential functions are the most complex part," said McWhorter. "We're using the AMS database to extract value when we go to commercial scale. The deployment of the AMS tool cut commissioning time significantly, so the operators could get a feel for the DCS. A lot of them never had touched a DeltaV before. Total time for 375 DSTs was about 90 man-hours."
One hitch Virent ran into initially, however, when it requested bids for the project, was a poorly defined scope. "We didn't define the scope of the project well enough at the beginning," said McWhorter. "It left the door open for the developer to deliver what they needed to deliver. A lot of the integration of the AMS and DCS was done at the same time. The system was developed without operation and system management in the DCS charter. AMS interface requirements were absent in the DCS development. And there were no bus protocols, so I had to use a lot of guessing and checking to debug the system, even though I knew that information was there. The lack of scope definition really meant premium charges to us because the bids accounted for lots of unknowns."
Secure Energy is using proven coal gasification and refining technology to set up a plant in Decatur, Ill. "We're developing on a modular basis," explained Kenny. "Our plan is to build five of these plants. We'll use 1.35 millions tons of coal per year to make natural gas."
The Decatur plant will have 86 employees. "There are 18 operating coal mines within 100 miles of us," said Kenny. "In the gasification process, we feed pulverized coal into the gasifier with steam and oxygen. We have two reactors. The coal, steam and oxygen go through the reactor. We don't burn the coal. The gas that comes out is a raw syngas. The molecules are altered. In the acid gas removal stage, we pull out the carbon dioxide and 99.999% of the sulfur. There's a little CO2 left in the stream. In the methanation step, we take the C02 and hydrogren and turn it into CH4 and compress it. It's a very exothermic process."
Emerson is Secure Energy's main automation contractor. Kenny estimates the plant will have more than 10,000 I/O points. The project plans to use DCS and SIS, tagging DeltaV, along with control valves, regulators, actuators and precision measurement tools for the control.
