Author Archives: zwilhoit

New Process Develops Additional Use for Waste Sulfur Stream

Sulfur is a common byproduct of the oil refining process: hydrodesulfurization produces around 0.5 lb of sulfur for every 19 gallons of gasoline that is processed [1,2]. A team led by professor Jeffrey Pyun and Ph.D. student Jared Griebel at the University of Arizona have developed a new process to create a useful polymer from this waste stream [1]. 

Sulfur Polymer Sample and Elemental Sulfur  [1]

Sulfur Polymer Sample and Elemental Sulfur [1]

 
A traditional use for elemental sulfur has been as feedstock for sulfuric acid [2]. However, recently, sulfur production is far outpacing market demand, and refineries are developing huge stockpiles of the material [1]. The new polymer developed at UA has potential uses as both a structural plastic and as a better constituent material in the Li-S rechargeable battery chemistry [1]. For these batteries, compared to traditional materials, the new polymer demonstrates improved properties of specific capacity and capacity retention [2]. The team, along with other co-authors, published their results in Nature Chemistry, and three companies are currently investigating commercial applications for the material [2,3].

[1] www.dailytech.com
[2] www.nature.com 
[3] azstarnet.com

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OSU Team Develops New Clean Coal Technology

A research group from Ohio State, led by Liang-Shih Fan, has developed a new type of clean coal technology called Coal Direct Chemical Looping (CDCL) [1]. The coal is reacted exothermically without combusting it with air. This process allows for careful control of pollutants and capture of 99% of CO2 emissions [1].

CDCL Cycle Overview

CDCL Cycle Overview [2]

Chemical Reaction

Chemical Reaction [2]

The pulverized coal is “directly” oxidized using heat and small beads of iron oxide in a sealed chamber where exhaust gases are easily captured [1]. Then, air is introduced to the spent iron beads in a separate chamber, re-oxidizing them and preparing them for reuse (the “looping”) [1]. This pair of reactions generates large amounts of heat which feeds the coal reaction and could also be used to generate steam for a traditional turbine cycle [1].

An experimental plant, illustrated below, was operated for over 200 consecutive hours in Fan’s lab, ultimately generating 25 kW of useful thermal output [1]. Based on the team’s success, the Department of Energy has issued a million-dollar grant for a large scale trial plant to be built in Ohio [3]. It will produce 250 kW of thermal output using a similar process tuned for syngas instead of pulverized coal [1].

Experimental CDCL Reactor

Experimental CDCL Reactor [2]

Simulations that the team ran in ASPEN plant modeling software indicated that a full scale plant would be 33% more expensive to operate based on $/MWh than a regular plant, but would capture 97% of the CO2 emissions [2]. For comparison, a plant with similar sequestration abilities using the current technology of monoethanolamine [MEA] stack scrubbing would capture 90% of emitted CO2 but would cost 71% more than a basic plant [2], [4].

Model Plant Economics

Model Plant Economics [2]

Model Plant Performance

Model Plant Performance [2]

The research performed by Fan’s group has produced a clean coal technology that would allow us to use our nation’s abundant coal resources while producing significantly fewer emissions at the smokestack — and at a price point that is significantly better than competing clean coal technologies.

[1] http://researchnews.osu.edu/archive/looping203.htm

[2] http://www.netl.doe.gov/publications/proceedings/12/co2capture/presentations/3-Wednesday/LS%20Fan-OSU-CDCL.pdf

[3] http://cbe.osu.edu/news/2012/08/l.s.-fans-patented-chemical-looping-process-moves-towards-commercialization-doe-investm

[4] http://www.pnnl.gov/main/publications/external/technical_reports/PNNL-20933.pdf

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