Natref: at the cutting edge of refining technology
The new expansion and upgrading project to increase Natref’s capacity by some 25 percent has been completed. The cost of the expansion was about R750 million. The expansion programme will increase the refining capacity of Natref to 108 500 barrels/stream per day.
The focus of the expansion is on meeting the expected growth in the market demands for fuels in the inland area, while it will also provide Total with the capacity to meet its own demands once the supply agreement with Sasol ends in 2004.
The expansion of Natref will enable it to convert more than 90 percent of its crude intake to white products. The refining energy efficiency will be improved and the environmental impacts of the proposed expansion will be mitigated. Natref has embarked on a 10-year emission reduction programme.
Natref has been certified in terms of the ISO 14001 Environmental Management System. Although the volume of crude to be processed will increase, assessments show that impacts on the environment resulting from expansion will be within the legal compliance limits and current refinery operating permits.
Commissioned in 1971, the Natref refinery at Sasolburg has been at the cutting edge of refining technology since its inception. Situated inland, near the industrial heartland OF South Africa, Natref (National Petroleum Refiners of South Africa) was no ordinary refinery.
With its inland location the refinery's market for heavy fuel oil was quite limited. As a result, it was designed to get the most out of crude oil and equipped with state-of-the-art technology. The refinery uses the bottoms up grading refining process using medium gravity crude oil and giving the refinery the capability of producing 70 percent more white product than coastal refineries that have to rely on heavy fuel oil.
Conversion of vacuum residue to white products (diesel, petrol, jet fuel and LPG) was a necessity from the start. Thus, in addition to a conventional fluid catalytic cracking (FCC) unit, the refinery was equipped with a distillate hydrocracker (DHC) and a black oil hydrocracker (BOC).
During the ensuing years, Natref has undergone a series of upgrading programmes. In 1993 some R450 million was spent on an upgrade and expansion project.
The 1993 upgrading project included the opportunity to re-examine the BOC-unit and to update the bottoms conversion technology to the latest available. The capacity of the refinery was increased by 10 percent to 86 000 barrels/stream per day and process heavier crudes. The capacity of the platformer was increased from 12 000 to 14 500 barrels/stream per day at an octane number of 95 enabling Natref to produce up to 60 percent of its gasoline as unleaded 93 octane.
While maintaining the same maximum throughput of 18 000 barrels/stream per day, the FCC in 1993 could process a much heavier feedstock. As for the black oil hydrocracker, its principle was changed completely. It now operates essentially as a catalytic feed preparation unit. It was transformed into reduced-crude desulphurisation unit.
The 1993 revamp was also an opportunity to install a recycle gas scrubber to remove the sulphur released from the feedstock. This system, now a standard feature on modern reduced-crude desulphurisation units, also prolongs catalyst life.
The Natref refinery is a joint venture between Sasol mining (Pty) Ltd and Total South Africa (Pty) Ltd. Sasol Mining has a 63,64 percent interest in Natref and Total South Africa a 36,36 percent shareholding.
A technical agreement exists between Natref and the Total Group.