Studies into the influence of wet torrefaction pretreatment on gasification of Larch wood and corn stalk
- 주제(키워드) wet torrefaction , dry torrefaction , gasification , influence , kinetics
- 발행기관 아주대학교
- 지도교수 Hyung-Taek Kim
- 발행년도 2017
- 학위수여년월 2017. 8
- 학위명 박사
- 학과 및 전공 일반대학원 에너지시스템학과
- 실제URI http://www.dcollection.net/handler/ajou/000000025446
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
It is generally known that the environmental pollution becomes one of the most serious problems in China. The contradiction between the energy demand and environment protection has become increasing apparent with society development and population growth. To solve this problem, it is essential to develop the renewable energy in China. The biomass energy, which is a kind of renewable energy, has aroused great attention in China for its abundance and environmental friendliness. Biomass gasification technology has been considered to be the most promising way for power, heat generation and various biofuels synthesis. In order to overcome the constraints of using biomass, it is recommended to be pretreated by torrefaction. Larch wood and corn stalk, as the representative of forest residue and agriculture residue, were studied in this research. Under the optimal condition, the solid product after wet torrefaction was analyzed with the proximate analyses, ultimate analyses, heating values, organic functional groups, SEM, BET and so on. The wet torrefaction was effective to improve the fuel properties of Larch wood and corn stalk. The wet torrefaction was compared with the dry torrefaction to find the best pretreatment method. It was found that the wet torrefaction had the features of lower temperature and shorter reaction period. As a result, the wet torrefaction was selected in this research. The ‘‘Torrefaction–Gasification’’ two-stage gasification flow chart was put forward. The raw biomass and wet torrefied biomass samples were both gasified with the gasifying agents of steam and CO2. The syngas production during gasification was mainly analyzed to testify the effect of wet torrefaction. During steam gasification, H2 and CO production during gasification of the wet torrefied biomass samples were higher than that of raw biomass samples, showing the superiority of the wet torrefaction. During CO2 gasification, CO is the main product, and the CO production was also significantly improved by wet torrefaction. The gas-solid reaction models were used to study the kinetics of gasification process, including VRM, SCM and RPM. The RPM proved to be the most suitable model for the gasification of biomass in this research. The structure change during gasification process was explained successfully by the RPM. . The results showed that the wet torrefaction pretreatment could reduce the activation energy of gasification compared with that of raw biomass, which was also found in CO2 gasification.
more목차
Chapter 1. Introduction 1
1.1 Background 1
1.2 Literature review 5
1.2.1 Biomass composition and the problems with utilization 5
1.2.2 Torrefaction technologies 9
1.2.3 Effect of torrefaction on gasification 12
1.3 Scope and Objective 17
1.4 Thesis outline 18
Chapter 2. Experimental method and apparatus 20
2.1 Characteristics of biomass samples 20
2.2 Experimental setup and procedure 22
2.2.1 Wet torrefaction 22
2.2.2 Dry torrefaction 23
2.2.3 Gasification 24
2.3 Other analysis methods 25
2.4 Equations 26
Chapter 3. Results and discussion 29
3.1 Results of wet torrefaction 29
3.1.1 Characteristics of torrefaction 29
3.1.2 Fuel properties of WTLW and WTCS 32
3.1.3 Comparison of wet and dry torrefaction 41
3.2 Characteristics of gasification of torrefied biomass 45
3.2.1 Carbon balance analysis 46
3.2.2 Syngas production during steam gasification 49
3.2.3 Syngas production during CO2 gasification 60
3.3 Kinetic study of gasification 67
3.3.1 Kinetic study of steam gasification 67
3.3.2 Kinetic study of CO2 gasification 79
Chapter 4. Conclusions 86
Reference 88
Nomenclature 101
Abbreviation 103
Curriculum Vitae 104
