Purdue University, funded by the U.S. Air Force Office of Scientific Research, has developed a facility aimed at learning precisely how coal and biomass are broken down in reactors called gasifiers.

Gasifiers are reactors in which biomass, coal or other carbon rich substances are heated and flooded with steam, oxygen or both.  Simply put, the heat decomposes the carbon-based molecules and the steam makes more hydrogen available for constructing the desired product coming out.  Gasifiers are messy and difficult to control reactors with intense operational experience needed and constant supervision for optimal output.  As Al Fin noted last week the sources for the heat can range from plasma to simple heating by fuels.

But what is actually happening in the gasifier?  Answering this matter would offer a great deal of knowledge on designs, construction and operations.  It would put solid scientific foundations into the synthetic fuel economy, which is not so far past the basic making of charcoal and saving back the exhaust gases in fuel forming.  Gasifiers are already quite interesting and have some potential for making fuels economically now.

Jay Gore, the Reilly University Chair Professor of Combustion Engineering at Purdue said, “A major focus is to be able to produce a significant quantity of synthetic fuel for the U.S. air transportation system and to reduce our dependence on petroleum oil for transportation.”  The research is part of work to develop a system for generating large quantities of synthetic fuel from agricultural wastes, other biomass or coal that would be turned into a gas using steam and then converted into a liquid fuel.

Other goals are involved, too. Learning how to generate less carbon dioxide than conventional synthetic-fuel processing methods while increasing the yield of liquid fuel by adding hydrogen into the coal-and-biomass-processing reactor and researchers are using the facility to learn how coal and biomass “gasify” when exposed to steam under high pressure in order to improve the efficiency of the gasification process.

Gore continues, “We want to show that our system is flexible for using coal and biomass. The aim is to create a sustainable synthetic fuel economy. What’s daunting is the size of the problem — how much oil we need — how much energy we need.”  This professor seems to get the scale issue.

A technique pioneered by Rakesh Agrawal, Purdue’s Winthrop E. Stone Distinguished Professor of Chemical Engineering for coal that generates less carbon dioxide than conventional synthetic-fuel processing methods while increasing the yield of liquid fuel by adding hydrogen into the coal-and-biomass-processing reactor showed last year in a paper that last year showed carbon dioxide might be reduced by 40 percent.  New findings will be detailed in a research paper being presented during a January meeting of the American Institute of Aeronautics and Astronautics in Orlando.

The research is already paying off.  Synthetic fuels currently are being blended with petroleum fuels for performance improvement in automobile and aircraft applications and also are used in equipment trials in commercial aircraft.

New techniques are needed to reduce the cost and improve the efficiency of making the fuels.  Gore said, “At the right price, synthetic fuels could replace fossil fuels in all conceivable applications.”

Gasifier Research Rig and Builders. Click image for more info.

The 2-meter-tall stainless steel reactor built by Purdue doctoral students is part of a system that borrows technology from aerospace applications, including a “spark igniter” used in space shuttle engines. Materials inside the spark igniter may briefly reach temperatures of up to 3,000 degrees Celsius, or more than 5,400 degrees Fahrenheit — hot enough to burn holes in steel.

The Purdue team has integrated an advanced optical diagnostics system: The information is obtained using a laser is transmitting through a window in the stainless steel vessel, passing through the gases being processed inside. An optical sensor on the other side of the vessel decodes the light to determine the precise temperature and composition of the gases produced.

“It’s a modular design, so the optical diagnostics part can be moved to various points to analyze how the gasification proceeds,” said Robert Lucht, the Ralph and Bettye Bailey Professor of Combustion in Mechanical Engineering.

The Doctoral students also designed a special feeder to transport the coal or biomass into the reactor vessel.

“One of the challenges is feeding this at high pressure — about 10 atmospheres,” Gore said. “This sort of feeder could not be bought off the shelf, so it had to be specially designed.”

That makes an innovation already available from just getting the research underway.

At the core is that information from the laser light.  Getting to grips with the temperatures and managing the flows of material and steam in a calibrated and throttled way should have a powerful impact and a chance at some automation with improved results.  It may be the laser sensor system itself has strong marketable properties.

Gasification is attractive for its simple but brutal operation.  Higher efficiency, cleaner output and more control over products can only help the economics.  As other sensor technologies are introduced gasification could be a leading refining technique for a wide range of raw materials from trash to cultivated biomass and on to coal.  Gasification might not be elegant – but the process enjoys the leading spot for going to commercial scale in today’s market for synthetic fuel processes.


1 Comment so far

  1. arjoon on June 1, 2019 6:04 AM

    A nicely written blog as it is quite informative and helpful. Thanks for sharing information

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