Lab-Scale Investigation of Catalyst Recovery Process in the Catalytic Steam Gasification of Low Rank Coal
Lab-Scale Investigation of Catalyst Recovery Process in the Catalytic Steam Gasification of Low Rank Coal
- 주제(키워드) Potassium carbonate , Catalytic steam coal gasification , Catalyst recovery , Recovery efficiency
- 발행기관 아주대학교
- 지도교수 김형택
- 발행년도 2015
- 학위수여년월 2015. 8
- 학위명 석사
- 학과 및 전공 일반대학원 에너지시스템학과
- 실제URI http://www.dcollection.net/handler/ajou/000000020125
- 본문언어 영어
- 저작권 아주대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
Coal gasification is an effective use of coal for power generation and syngas production. In addition, it has advantages in emission control and CCS. In recent years, the study of catalytic gasification has received attention because it requires less thermal energy input but products higher carbon conversion. However, use of catalyst in coal gasification suffers from serious economic constraints because of the high costs of catalyst, as well as environmental impact of gasified char if it disposed by conventional landfill. Therefore, due to both economic and environmental reasons, catalyst recovery is necessary. In the present study, extraction schemes were investigated including water washing, limewater (CaO, KOH) washing and water-limewater-combined washing, respectively, in order to evaluate their efficiency of extraction. In this research, catalyst recovery process from gasified residue from steam gasification with Lanna raw coal catalyzed with 20 wt.% Potassium carbonate (K2CO3) on a laboratory fixed-bed reactor. Effects of process variables, such as reaction time, temperature and residue/solution weight ratio, on the extraction efficiency were evaluated. The optimal experiment condition for catalyst recovery were 150 ℃, 20/1, 2 h. In conclusion, water-limewater-combined washing was found to be the most desirable because of it costs was lower than limewater washing and its efficiency was high enough to accept. In addition, it was proven that the recovered potassium has the same catalytic activity as potassium carbonate.
more목차
CHAPTER 1. INTRODUCTION 1
1.1 Catalytic gasification 1
1.2 Low rank coal 6
1.3 Necessity of Catalyst recovery 9
1.4 Literature review of catalyst recovery research 12
CHAPTER 2. EXPERIMENTAL APPARSTUS AND OPERATING PROCEDURE 16
2.1 Sample preparation 16
2.1.1 Coal sample 16
2.1.2 Catalyst and loading method 17
3.1.3 Limewater 18
2.2 Experimental methodology 20
2.2.1 Catalytic steam gasification stage 20
2.2.2 Catalyst recovery stage 21
2.3 Others analysis methods 25
2.4 Data processing of carbon conversion, recovery efficiency 26
CHAPTER 3. RESULTS AND DISCUSSION 27
3.1 Results of experimental study on characteristics of catalyst recovery process 27
3.2 Results of effect on recovery efficiency by changing reaction temperatures, reaction time and solution-to-residue weight ratios 29
3.3 Effect on recovery efficiency by utilizing different washing methods 35
3.1.1 Water washing 36
3.1.2 Limewater washing 40
3.1.3 Combined washing 45
3.4. SEM/EDX and XRD analyses on recovered residues through utilizing different washing methods 48
3.5. Comparisons on gasification effects by using recovered potassium catalyst and fresh K2CO3 catalyst 54
CHAPTER 4. CONCLUSIONS 56
REFERENCE 57
