Article pubs.acs.org/EF
Development of a Coupling Oil Shale Retorting Process of Gas and Solid Heat Carrier Technologies Qingchun Yang, Yu Qian, Huairong Zhou, and Siyu Yang* School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510641, People’s Republic of China S Supporting Information *
ABSTRACT: Oil shale is one of the most potential alternative resources for crude oil. Its exploration and exploitation are of increasing interest. In China, oil shale is mainly used by retorting technology. Fushun-type retorting technology, a typical gas heat carrier retorting technology, accounts for the largest proportion in China. However, this retorting technology is only applicable of coarse oil shale particles bigger than 10 mm in diameter. A lot of fine oil shale particles are discarded, resulting in waste of resources. Besides, this technology is criticized by low economic benefit. The main objective of this paper is to develop a coupling oil shale retorting process. The novel process can use fine oil shale particles as the raw materials of solid heat carrier retort to produce more shale oil. The novel process is modeled, and next, the simulation is carried out to build its mass and energy balance. From the techno-economic point of view, the advantages of the novel process are demonstrated by comparison to the traditional Fushun-type oil shale retorting process. Results indicate that the novel process is promising because coupling the two retorting process can increase the shale oil production from 13.86 to 17.34 t/h, the exergy efficiency from 32.46 to 38.01%, and the return on investment from 11.04 to 18.23%.
1. INTRODUCTION The reserve of oil shale resources is the second largest among all fossil fuels if converted into heat.1 Chinese oil shale resources are about 7.20 × 1011 t, i.e., 4.76 × 1010 t of oil in place shale oil.2 With the severe energy shortage, developing environmental and economic oil shale retorting technologies are currently the focus of many countries, including the United States and China. There are many different and industrialized oil shale retorting technologies of gas heat carrier, such as Estonian Kiviter retort,3 Brazilian Petrosix retort,4 and Chinese Fushun-type retort.5 There are many advantages in Fushun-type oil shale retorting (FsOSR) technology: (1) it can use low oil content oil shale; (2) its flow sheet is simple; and (3) it is easy to operate and maintain.6 It has been widely used in China. The block diagram of a conventional FsOSR process is illustrated in Figure 1. The coarse oil shale particles bigger than 10 mm in diameter are heated to 520 °C and reacted to produce an oil−gas mixture and ash in the retort. The mixture is subsequently fed to the water scrubbing and the flash separation to obtain retorting gas and shale oil. However, there are also many shortcomings in this technology: (1) The FsOSR process can only use the coarse oil shale particles bigger than 10 mm in diameter. However, the fine oil shale particles produced from the grinding process are 20−40% of the total oil shale. The maximum resource efficiency of the FsOSR process is about 60−80%.6 (2) The shale oil yield of the FsOSR process is about 60−75%.7 (3) The economic performance of the FsOSR process is unsatisfactory. Its return on investment is lower than 12% in general.8 Besides the oil shale retorting technologies of a gas heat carrier, there are also many different and industrialized oil shale retorting technologies of a solid heat carrier. Among these © XXXX American Chemical Society
technologies, Chinese Dagong oil shale retorting (DGOSR) technology is of great interest because its oil yield is up to 90% and has a good economic benefit.9 This technology has been applied to a 1.2 × 106 t/year lignite retorting plant in Shenmu, Shaanxi, China. Besides, a 2000 t/day oil shale retorting plant is also being industrially demonstrated in Daqing, Heilongjiang, China.6 Its block diagram is presented in Figure 2. The fine oil shale particles (
