Chinese pilot plant for coal-to-liquid facility to start up this March
miningweekly.co.za
THE COMPLETED PILOT PROJECT IN BAOJI Technology derived from this project will mean a CTL process that is cheaper, cleaner, more efficient and uses less water
Published: 14 Mar 08 - 0:00
The severe winter weather conditions in China have delayed the start-up of a pilot plant using a Fischer-Trospch (FT) technology developed at the University of the Witwatersrand’s Centre of Material and Process Synthesis (Comps) to convert coal to liquid fuels using a process usually referred to as coal-to-liquid (CTL). The Golden Nest International group is funding the project at a cost of about R75-million.
This South African developed technology can be applied in CTL processes at a reduced capital cost, decreased carbon dioxide (CO2) emissions, as well as reduced operating costs, simplicity of operation and ease of scalability when building a larger facility with an increased output.
The technology is the result of the application of the process synthesis and optimisation methods developed at Comps and its collaborations with other world leaders in the field. The methods were used to identify and reduce, systemically, or eliminate inefficiencies inherent in a conventional process flow sheet design.
Since the invention of the original process by the German researchers Franz Fischer and Hans Tropsch, working at the Kaiser Wilhelm Institute in the 1920s, many refinements and adjustments have been made, and the term ‘Fischer-Tropsch’ now applies to a wide variety of similar processes for which the basis remains the same. On a commercial level, other CTL producers like petrochemicals giants Sasol and Shell use the technology for their CTL fuels.
The technology being used by Comps is not based on any other commercial technology nor does it infringe any other party’s intellectual property rights. It represents a significant opportunity for the production of liquid fuels with a reduction in the associated CO2 emissions.
The group has developed the field of process synthesis to permit the rapid determination of optimal process pathway and design. To obtain and evaluate these solutions, it has developed a range of new techniques, including fundamental analysis, experimental measurements, modelling and optimisation tools.
The difference of the Comps design is that it is a one-pass process. The elimination of the recycle stream improves not only the operability of the process but also the requirement for equipment essential for the operation of the recycle-based system.
These items of equipment include upstream air separation for gasification, reformers for the recycle of methane from the tail gas and the requirement for complex and expensive gas separation for the recycle process. Removal of this equipment and its associated operating costs have a significant impact on the profit- ability of the process.
Conventional commercial FT technologies make use of a pure oxygen feed with a large process recycle. This requires the inclusion of capital-intensive items of equipment. This affects not only the capital and operating costs of the process, but also increases the CO2 emissions of the process. The elimination of this equipment permits a significant cost saving as well as a reduction in the CO2 emissions by as much as 20% a ton of liquid fuels produced.
The technology is a combination of a fixed-bed catalytic system and an interconnection of the process units. This offers significant benefits to the process at a minimum of technology risk as the major equipment items all incorporate demonstrated and proven technologies.
The Comps design is less capital intensive, it is based on proven technology and implementation strategies and is simpler to start up and operate than other commercial technologies. In addition to these benefits, the proposed process design offers reduced water consumption and CO2 emissions when compared with other commercial technologies.
Once demonstrated at the pilot plant, the scale-up of the reactor system to the desired commercial scale will be relatively simple and of a shorter timeframe. Initial results from the pilot project are expected in the third quarter of this year.
The pilot FT facility has been constructed on the site of the BaoDan ammonia plant on the outskirts of the city of Baoji, in the Shaanxi province of the People’s Republic of China. The city of Baoji has a population of about one-million and is a two-hour drive to the west of the provincial capital of Xi’an.
The basic engineering for the Baoji plant was done by engineering contractor KBR, in Johannesburg, with the detailed engineering being undertaken by the Shanghai Chemical Industry Design Institute. Construction of the Baoji plant was completed at the end of 2007 and start-up is planned for this March, once the severe winter conditions have abated. The facility contains five reactors, each 14 m tall by 0,5 m in diameter.
The FT facility uses a feed stream of carbon monoxide and hydrogen (syngas) taken from the BaoDan ammonia plant. This syngas is then purified in a gas clean-up process, where the sulphur content is reduced to less than 40 parts per billion (ppb). The purified gas stream is then supplied to the bank of five high-pressure reactors.
There is a coal reserve of some ten-billion tons at Baoji. A coal mine is being developed at a cost of eight-billion RMB over the next five years. The coal production would reach 15-million tons a year. It is a provincial government requirement that beneficiation of coal has to be done in the province where it was mined.
Part of this yearly output would be used to develop a chemicals park, with the possible inclusion of a minimum 480 000 t/y FT plant using Golden Nest’s technology. Local laboratory workers will be trained in the procedures required for the project.
The Comps team is headed up by Professor David Glasser, Professor Diane Hildebrandt, process manager for the Golden Nest project Dr Brendon Hausberger and Comps project manager David Milne. A team of graduate chemical engineers, most of whom hold PhDs in chemical engineering, supports them.
They have all had to learn some Mandarin and immerse themselves in the Chinese culture in which they find themselves for long periods.
Comps is in discussions with major mining institutions in South Africa to bring the technology to South Africa. It would mean a cheaper, cleaner and more efficient process that uses less water.
Edited by: Esmarie Swanepoel |
