Design, Optimization and Economical Evaluation of Coal-based Poly-generation Process to Produce Chemicals

• Main Authors: Bor-Yih Yu, 余柏毅
• Other Authors: I-Lung Chien
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/7bjr9e

博士 === 國立臺灣大學 === 化學工程學研究所 === 105 === In this work, the design, optimization, and economic evaluation of coal-based poly-generation processes to produce different kind of chemicals are investigated. We lack energy sources in Taiwan, thus over 98% of the energy sources come from importation. Among those energy sources, coal has several advantages such as its relative low proce, abundance, and easy transportation. Therefore, coal has been one of the most important energy sources in Taiwan, and it is expected that its role will be retained in the future. Gasification is the center of this kind of processes, which is also the starting point of this work. Firstly, a 1-dimension gasifier model is established to investigate the gasification performance of coal or biomass under different operating conditions. After that, the coal-to-synthetic natural gas (SNG) and coal-based poly-generation process to produce SNG and ammonia are followed. Because importation of natural gas required liquefaction and compression, thus the importation price is quite expensive in Taiwan (11.3~11.7 USD/MMBTU). Thus, converting coal into SNG can be economically attractive (10.336 USD/MMBTU). If the poly-generation configuration is adopted, the economic performance can be further enhanced. But the enhancement of economic performance may be not obvious once one of the product flowrate is too small. The next topic to investigate is the novel methanol-to-olefin (MTO) process, and the main products are ethylene and propylene. In this work, the rigorous simulation of this process is studied, and the influences from variables are carefully investigated. Besides, due to the close boiling point between propylene and propane, separating them through distillation is not easy. Thus, four method for separation propane with propylene are studied. They are traditional single-column separation using steam as the heat source (case 1), using waste hot water as the heat source (case 2), distillation with the vapor recompression cycle (case 3), and the extractive distillation using acetonitrile solution as the entrainer (case 4). From the results, it is found that case 2 and case 4 may be economically attractive. The final topic is the syngas-to-ethylene glycol (EG) process. There are two stages in this process. In the first stage, CO in syngas is converted into dimethyl oxalate (DMO) as an intermediate, while in the second stage, DMO is hydrogenated to become EG. In the first stage, the circulation rate of methanol inside the process is the most important one. It is mainly determined by the ratio of methanol to the combined nitric oxide and nitric dioxide flowrate into the packed-bed reactor. In the second stage, the most influential variable is the molar ratio of hydrogen and DMO in the combined feed. In short, many coal-based poly-generation processes for producing chemicals are rigorously studied in this work. The analysis methods include optimization, heat integration, economic and energetic evaluation. Through this work, a better understanding toward these processes can be obtained.