Coal and biomass conversion under supercritical water conditions
Abstract/Contents
- Abstract
- Coal has been used as a resource for power generation for over a century. Due to its low cost and abundance, a large amount of coal and biomass is still being used to generate electricity throughout the world. Given that these solid fuels are here to stay for the foreseeable future, the problem of their environmental impact in terms of their emission of CO2 and harmful gas streams will remain unless solutions can be found. In this study, a feasible option to sequester CO2 and harmful gas streams has been investigated. Supercritical water is an attractive medium for power generation because of its special characteristics. Organic compounds extracted from coal and biomass hydrolyze, and they are completely miscible in supercritical water. In contrast, sulfur, chlorine and many trace elements in coal are oxidized and form insoluble salts in supercritical water, which precipitate and can be removed. The coal/biomass-to-electricity scheme proposed in this dissertation takes advantage of these characteristics of supercritical water in using it as a reaction medium. Coal/biomass devolatilization and char gasification models are introduced in the dissertation. Also provided are an analysis for coal gasification with water at various conditions and a description of the experimental facility to conduct experiments for pulverized coal and biomass conversion under supercritical water conditions (P> 218 atm and T> 647 K). The facility includes high-pressure water pumps, pulse-dampening accumulators, a water preheater, an oxygen booster, a supercritical water gasification reactor, and a reaction quenching cooler. This work presents the entire coal/biomass conversion system, built and assembled, which permits the acquisition of data needed to determine the rate coefficients for reactions that are suitable for supercritical water conditions. The focus of the facility is a flow reactor that can be pressurized to up to 340 atm at temperatures of up to 750 K. The continuous flow reactor is 15 meters long, sufficient for residence times of up to 15 minutes when the total mass flow rate (slurry plus supercritical water flow rates) is 20 grams/min. This work also presents the detailed operational procedures for coal/biomass conversion experiments under supercritical water conditions. In addition, the early operational runs for Wyodak coal conversion under 240-245 atm and 350-385°C and their results are discussed.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Kim, Bum Jick |
|---|---|
| Associated with | Stanford University, Department of Mechanical Engineering |
| Primary advisor | Mitchell, Reginald |
| Thesis advisor | Mitchell, Reginald |
| Thesis advisor | Cappelli, Mark A. (Mark Antony) |
| Thesis advisor | Edwards, Christopher |
| Advisor | Cappelli, Mark A. (Mark Antony) |
| Advisor | Edwards, Christopher |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Bumjick Kim. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Bum Jick Kim
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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