Biomass-to-Syngas Conversion

 

Because of converging concerns about global climate change and depletion of conventional petroleum resources, many nations are looking for ways to create transportation fuels that are not derived from fossil fuels. Biofuels and hydrogen (H2) have the potential to meet this goal. Biofuels are attractive because they can be domestically produced and consume carbon dioxide (CO2) during the feedstock growth cycle. Hydrogen is appealing because its use emits no CO2, and because hydrogen fuel cells can be very efficient. Today most hydrogen is derived from syngas, a mixture of hydrogen, carbon monoxide (CO) and carbon dioxide, which is produced through catalytic steam reforming of methane (CH4). Although effective, this process still produces CO2. Another method used to generate hydrogen is water electrolysis, but this process is extremely energy intensive. Thus, finding an energy-efficient approach to producing hydrogen from biofeedstock is appealing. The Ellzey group's work involves a non-catalytic fuel reforming process known as filtration combustion (see Figure1). In this process, a fuel-rich mixture of air and fuel is reacted in an inert porous matrix to produce syngas. Some of the fuel and air mixtures under study lie outside the conventional rich flammability limits, meaning that at standard temperature and pressure these mixtures will not ignite. These mixtures react because high local temperatures are created as the reaction front propagates into a region where the solid matrix has been heated by exhaust gases. These high temperatures effectively broaden the flammability limits, allowing the mixture to react and break down the fuel into syngas.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 1. Filtration Combustion

 

 

The overall goal of this project is to test the use of filtration combustion with many different biofuels, from corn ethanol to heavier biofuels such as algae oil. Although hydrogen yields and efficiency are the main concern, the exhaust composition as a whole is also of interest. In order to maximize hydrogen production and confirm computational models of the experiment, various parameters like inlet velocity and equivalence ratio (fuel to air ratio) are altered and the results are investigated.

 

 

Current work on Wet Ethanol

 

Though there are many biofuels, ethanol (C2H5OH) is a popular choice for replacing fossil fuels. However, many have questioned its value as a renewable fuel since it requires a significant amount of energy to produce, especially from corn. Producing pure ethanol requires substantial energy for distillation and dehydration to yield an appropriate "dry" fuel for traditional combustion engines. Wet ethanol, or ethanol that has not been fully distilled and dehydrated, requires significantly less energy to create than pure ethanol. Our first goal in this research was to produce hydrogen-rich syngas from wet ethanol. The presence of water in the reactant fuel can increase the hydrogen mole fraction and decrease the carbon monoxide mole fraction of the product syngas, both of which are desired effects. Also, because there are no catalytic surfaces, the problems of coking and poisoning that typically plague biomass-to-hydrogen reforming systems are eliminated. This also adds another parameter that can be varied and studied, the water fraction of the fuel. As of spring 2009, both experimental and computational work has been published using wet ethanol as a fuel. The current focus is on developing a better experimental setup that will allow group members to confirm these initial findings and move on to heavier biofuels.

 

Project Leads: Colin Smith

 

 

 

Counterflow Reactor Design and Manufacture

 

Current advances in mobile devices are bringing about power demands that are quickly outpacing available battery technologies. Portable power systems based on fuel cells promise higher power densities, but face challenges with respect to the storage of suitable fuels. Hydrocarbon fuels offer high power densities and can be reformed into a hydrogen-rich syngas, which, once purified, can be used to power hydrogen-operated fuel cells. In order to reform these hydrocarbon fuels, the Ellzey group has developed a novel non-catalytic mesoscale fuel reformer concept, which is based on heat recirculation between parallel channels with opposing flow directions (see Figure 1). This heat recirculation allows for the creation of stationary combustion zones that react fuel and air mixtures beyond the conventional rich flammability limit. This means that fuel-rich mixtures that will not ignite at standard temperature and pressure are able to react in the high temperature environment created by the counterflow design. These fuel-rich conditions are favorable for syngas production. Over the past several years, Dr. Ingmar Schoegl developed a working prototype of the proposed reactor and confirmed that the groups members' theoretical and computational predictions were correct.

 

 

 

 

 

 

 

 

 

 

 

Figure 1. Reactor Design

 

 

Current Work with SLS Manufacturing

 

Although a working reactor design has now been developed, commercial viability of such a device necessitates that it is rugged and easily produced. To that end, group members are investigating the use of Selective Laser Sintering (SLS), which was developed here at the University of Texas, as a method of producing the reactor from a single block of material. Due to tolerances of the sintering process, further design of the reactor and experimentation are necessary, alongside further investigations into streamlining the manufacturing process as a whole and maximizing the reforming characteristics if the reactor for real-world use. As of spring 2009, a counterflow reactor has been manufactured using SLS and successfully ignited; current work involves manufacturing a second reactor for further testing and investigating operational hazards such as coking.

Project Leads: Ingmar Schoegl, Jonathan Gaspredes

 

 

 

Rail Gun/Armature Design

 

Project Description coming soon.

 

Project Leads: Doyle Motes

ellzey coMbustion group

Projects

Utilizing Combustion to Meet the World's Energy Challenges.