Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


osu1187199715.pdf (2.92 MB)

ETD Abstract Container

Abstract Header

Development of chemical looping gasification processes for the production of hydrogen from coal

Velazquez-Vargas, Luis Gilberto
http://rave.ohiolink.edu/etdc/view?acc_num=osu1187199715

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Chemical Engineering.
Two chemical-looping gasification systems, the Syngas Redox (SGR) process and the Chemical Looping Reforming (CLR) process, were developed for the production of hydrogen from coal. Both processes are based on the cyclic reduction and oxidation reaction of iron oxide composite particles. In the SGR process, coal reacts first with a mixture of steam and oxygen to produce syngas. The syngas is then oxidized in a fixed-bed reactor to carbon dioxide and water vapor by iron oxide particles, simultaneously reducing these particles to their metallic form. The metallic particles are oxidized by steam after breakthrough is seen, regenerating them into iron oxide, while producing pure hydrogen. To produce hydrogen continuously, two or more reactors can be operated in alternating modes. Coal gasification and particle reduction are combined in a single reactor in the CLR process. The reactions are performed in a moving-bed reactor, with particles flowing countercurrently to the reactant gas. After reduction by coal in the first reactor, the particles are transported pneumatically by inert gas to a second moving bed reactor where they are oxidized with steam, producing a near-pure hydrogen stream. Following this oxidation, the particles are transported back to the first reactor to repeat the reduction process. Extensive work was performed on particle development, where iron oxide was identified as the optimum metal oxide for use in the processes due to the combination of favorable thermodynamic equilibria, reaction rate, and stability at high temperatures. The SGR and the CLR processes were demonstrated in a bench scale reactor setup. Experiments proved that these processes can produce pure CO 2and H 2streams as predicted. Process simulations showed that the SGR and CLR can reach theoretical efficiencies ranging from 74% to 86%, respectively, with no additional carbon dioxide separation or extensive cleaning operations. Due to the high conversion efficiencies, good economics and environmental benefits, these processes are attractive for the large scale production of hydrogen from coal. Hence, this work also includes designs for a pilot scale reactor unit to perform large scale demonstrations. The unit is designed to produce continuously about 25 kW (thermal) of hydrogen from coal.
Liang-Shih Fan (Advisor)
236 p.
chemical looping gasification; hydrogen production; coal combustion

Recommended Citations

Citations

  • Velazquez-Vargas, L. G. (2007). Development of chemical looping gasification processes for the production of hydrogen from coal [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1187199715

    APA Style (7th edition)

  • Velazquez-Vargas, Luis. Development of chemical looping gasification processes for the production of hydrogen from coal. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1187199715.

    MLA Style (8th edition)

  • Velazquez-Vargas, Luis. "Development of chemical looping gasification processes for the production of hydrogen from coal." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1187199715

    Chicago Manual of Style (17th edition)

osu1187199715
3,128
© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.