tech focus by the publishers of popular mechanics a … · recarburiser coke – metallurgical...

Technology solutions for an energy-hungry world

A globAl force

> >

It’s taken nature millions years of years to create the black gold that powers humankind’s relentless march of progress. It takes just seconds to unpack the potential of the

hydrocarbon molecule that forms the basis of fossil fuels.And in our energy-hungry world with its ultimately limited resources, it’s clear that we need innovative approaches in the fierce pursuit of alternative energy solutions.

It’s exactly that kind of pioneering, resourceful, even contrary, mindset that set Sasol on its long, lonely road half a century ago.

But what started as an import replacement programme has moved significantly forward. Today, Sasol is an integrated oil and gas company with substantial chemical interests. In Southern Africa, Sasol supports these operations by extracting coal and natural gas and converting this into synthetic fuels and chemicals through proprietary Fischer-Tropsch technologies.

With more than 30 000 employees, Sasol also has chemical manufacturing and marketing operations in Europe, Asia and the Americas. Its larger chemical portfolios include polymers and solvents, and their intermediates, waxes, phenolics and nitrogenous products.

The group refines imported crude oil into liquid fuels in South Africa and retails liquid fuels and lubricants through a growing network of Sasol convenience centres and Exel service stations. Natural gas is produced in Mozambique for supply to customers and as feedstock for some of the company’s fuel and chemical production in South Africa.

In addition to this, in Qatar and Nigeria two gas-to-liquid fuels joint ventures are being developed that will incorporate the proprietary Sasol Slurry Phase Distillate™ process. To complete the picture Sasol is also involved in the production of crude oil in offshore Gabon.

Against this formidable background, Sasol is poised to take its unique processes to the next stage: technology solutions for an energy-hungry world.

TECH FOCUS By the publishers of PoPular Mechanics, in collaboration with Sasol

POPULARMECHANICS.CO.ZA • MARCH 2007

The fully integrated, three-step Sasol Slurry Phase Distil-late™ (Sasol SPD™) process dates back to the 1980s when

Sasol developed its low-temperature Slurry Phase Fischer-Trop-sch reactor at Sasolburg. Combined with a proprietary iron- or cobalt-based catalyst, this technology allows for the creation of chemicals and liquid fuels from either coal or gas.l Gas reforming Firstly, natural gas reacts with oxygen and

steam over a catalyst to produce synthesis gas (syngas). To achieve this, Sasol and its global GTL partners use Haldor Topsøe’s proven autothermal reforming technology.l Fischer-Tropsch synthesis The second process step entails converting syngas into longer-chain or waxy hydrocarbons in the reactor. Syngas is fed to the bottom of the reactor where it is distributed into a slurry consisting of liquid wax

Hydrocarbon alchemy Take one serving of coal or gas. Add some proprietary magic. Welcome to today’s petrochemicals business.

A graphic representation of an alpha olefin hexene molecule.

By 1953, Sasolburg was taking shape. Fuel production began in 1955.

Today, the Sasolburg factory is dedicated to chemicals production.


and particles of Sasol’s proprietary advanced cobalt catalyst. As the gas bubbles up through the slurry, it diffuses into the catalyst and is converted into waxy syncrude. The long-chain wax product is then separated from the slurry containing the catalyst particles in a proprietary Sasol process. The lighter, more volatile fractions leave in a gas stream from the top of the reactor. The gas stream is cooled to recover the

Hydrocarbon alchemy Take one serving of coal or gas. Add some proprietary magic. Welcome to today’s petrochemicals business.

Going greenSasol invested more than R6 billion at Sasolburg and Secunda to modify its fuel production facilities to ensure compliance with South Africa’s stricter global-compliant diesel and petrol specifications that became mandatory in 2006.

Growing tomorrow’s dieselSasol’s South African biodiesel study is advancing and has been formally approved by the group executive committee to proceed to a full-scale feasibil-ity study. This study is aimed at establishing a technically and economically feasible process for producing a high-perform-ance diesel from a renewable source such as soybeans.

hydrocarbons that have a lower molecule weight (the lighter cuts), as well as some quantities of water.l Isocracking™. The hydrocarbon streams are then sent to the product-upgrading unit for the third step, which uses Chevron Isocracking™ technology. This step produces the final gas-to-liquids (GTL) diesel, GTL naphtha and liquefied petroleum gas (LPG).

Below ground, in Sasol’s own mining operations, it’s been every bit as much of a leader: here’s a world first, a curved underground conveyor at the Middelbult colliery, Secunda.


Hydrocarbon feedstockSasol Mining at Secunda supplies most of the feedstock coal needed for the Secunda petrochemical plant. Mozambican natural gas is used as the feedstock at Sasolburg and a

supplementary feedstock to coal at Secunda.

Gas productionGasification condensates, once cooled, yield tars, oils, pitches and associated co-products. Ammonia, sulphur and phenolics are also recovered.

The catalytic cycle. Synthesis gas is fed into the Sasol reactors, where it reacts with the catalyst and is converted to longer-chain or waxy hydrocarbons.

Using the Fischer-Tropsch process

to produce fuel oil from South Africa’s

abundant coal reserves, Sasol was

able to celebrate the opening of its first

commercial oil-from-coal petrol pump at Parys, near its

factory, in the 1950s.

Heart of the matterAn ingenious oil-from-coal concept launched an entire industry: the Fischer-Tropsch process

Coal-to-liquids (CTL) is where Sasol started. South Africa’s vast coal reserves, coupled with a desire for oil-supply

independence in the post-World War 2 years, prompted the country to adopt the oil-from-coal process patented by German scientists Franz Fischer and Hans Tropsch in 1925.

In the Sasol process, synthesis (syngas), produced through both coal gasification and natural gas reforming, is converted, by using the Sasol high-temperature Fischer-Tropsch technology, into synfuels, chemical feedstock and pipeline gas. Sasol Synfuels produces most of Africa’s chemical building blocks, including ethylene, propylene, solvents and phenolics.

Essentially, raw “synthesis gas” is derived in huge reactors (gasifiers) fed by coal in the presence of steam and oxygen under pressure.

At the micro level, combining carbon, oxygen and steam under controlled conditions at high temperature and pressure, produces the requisite gas. Downstream processes that include cooling, removal of by-products such as sulphur and ammonia, and further chemical reactions, produce liquids that form the basis of fuels and chemicals. Whether the end product is fuel oil or wax, for example, depends to a large extent on using the right combination of temperature, pressure and catalyst to produce the required category of hydrocarbon chain length.

Since starting up in the 1950s, Sasol has undertaken extensive research and development in Fischer-Tropsch synthesis technology and patented several processes and specialised catalysts.

Given that there’s still no great shortage of coal, Sasol is looking to expand this part of its operations.

As part of this drive Sasol has engaged with a Chinese consortium to further explore the potential for development of CTL plants in China.

reactant Product reactant

reactiveIntermediate

Absorbed species

catalyst


HiGH-TEMPErATUrE SynGAS COnvErSiOnAt Secunda, purified synthesis gas is sent to the Sasol Advanced Synthol (SAS) reactors, where the hydrogen and carbon monoxide react, under pressure with the aid of an iron-based catalyst at a temperature of about 350˚ C, to yield C1 to C20 hydrocarbons. These are cooled successively in a product recovery plant until most components become liquefied. By exploiting differences in boiling points, separate hydrocarbon-rich fractions can be derived, as well as methane-rich gas, some of which is sold as pipeline gas.

The C2-rich stream, a mixture of ethylene and ethane, is recovered to produce ethylene derivatives. Propylene is purified from the light hydrocarbon gases to provide feedstock for the Secunda polypropylene plant and Sasolburg butanol plant.

Proprietary Sasol technology allows the recovery of 1-pentene, 1-hexene and 1-octene for international customers from the C4 to C20 stream. Oxygenates from the SAS aqueous stream are separated and purified in the chemical workup plant to produce alcohols, acetic acid and ketones.

LOw-TEMPErATUrE SynGAS COnvErSiOnAt Sasolburg, the Sasol Slurry Phase Fischer-Tropsch ( FT ) process converts syngas at a lower temperature than the SAS reactors. This produces linear-chained hydrocarbon waxes and paraffins. Some of the synthesis gas is used to produce methanol, ammonia and butanol. Ammonia is used for the production of ammonium nitrate-based explosives and fertilisers.

A graphic representation of the Sasol Slurry Phase DistillateTM process, which employs unique technology that will be key in producing high-quality diesel.


From A to Z:Sasol products in your daily life

When you wake up in the morning and switch on your bedside lamp, you’re probably not even

aware of the argon gas contained in the light bulb or the chemicals in the cream you apply to your skin.

Your cosmetics use Sasol waxes, and those distinc-tive scents wouldn’t be the same without the ethanol used to formulate them. As you drive to work, not only could your vehicle be powered and lubricated by Sasol, it probably uses many components derived from chemicals and possibly started its life as raw material worked in furnaces fired by the company’s high-quality carbon products, such as calcined pitch coke. Your lunch was likely grown in soils enriched by fertilisers produced by Sasol Nitro. After a hard day’s work, your favourite soapie comes to you cour-tesy of electronic products that depend on phenolics for microchip coatings and production of printed cir-cuit boards. As night falls, that candlelit dinner owes its romantic light to the waxes produced by Sasol Wax. And, if you’re thinking ahead to the big game at the weekend, remember that everything from goal nets to the moulded soles of boots and the skins of balls are the result of polymers. It’s virtually an entire alphabet of really useful information.

Polypropylene produced by Sasol Polymers is converted into a wide range of moulded plastic products, including automotive components.

waxes are used in crayons, makeup and coatings.

Left: Lightbulbs use argon extracted from Sasol’s air-separation plants.

Below: The moulded soles of boots and the skins of soccer balls – as well as the goalnets – are produced from polymers.

vitamin- and mineral-rich fruit, vegetables and cereals are fed on fertilisers produced by Sasol nitro.

Sasol occupies our daily lives in countless

ways, from fuel to the waxes that form the basis for everything from “chewing gum to floor polish”, as one executive famously put it.


Argon – inert gas essential in lightbulbs

AceTone – nail varnish

buTAne – lighter fuel

bITumen – roads

DIesel – powers trucks, tractors and increasingly cars

eThylene gAs – banana-ripening

eThAnol – perfumes and deodorants

ferTIlIsers – derived from ammonia

gAses – such as carbon dioxide and nitrogen forindustrial use

hyDrogen – manufacture of margarine

InDusTrIAl PIPelIne gAs – heating furnaces, ovensand kilns

JeT fuel – derived from crude oil and synthetic components

KryPTon – lasers and lighting

lIneAr-chAIn AlPhA olefIns – enhancing plastics

mono-meThylAmIne – agrochemicals and explosives

nITrIc AcID – nitrogenous explosives

orTho-cresol – and other phenolics, used for specialised coatings

PolyVInyl chlorIDe – PVC

ProPylene – polypropylene packaging and car parts

recArburIser coKe – metallurgical production

soDIum TrIPolyPhosPhATe – washing powders

TerTIAry Amyl meThyl eTher – octane-boostingpetrol additive

ureA, DerIVeD from AmmonIA – animal feeds

WAxes – crayons, makeup, coatings

xenon – projectors, medical scannersit’s hard to believe injection-moulded plastics can start life deep under the earth…

Even bakers find Sasol useful: propionic acid forms the basis of calcium propionate, used to help keep bread fresh.

Sasol Solvents exports about 350 000 tons of solvents a year to customers in more than 80 countries, for use in paints, inks, personal-care products and pharmaceuticals.

Home Theatre – and a lot else besides – simply wouldn’t exist without phenolics to help coat microchips in our computers, cellphones, audio systems and other electronic equipment.

i-Hexene, produced by Sasol, is an important copolymer that helps create cling-wrap, plastic shopping bags and related consumer plastics; polyvinyl chloride (PvC) is everywhere in applications ranging from juice bottles to car trim.


With high crude oil prices and diminishing oil reserves, it’s no surprise that there’s a fierce drive to find

alternative sources of fuel to run vehicles. Natural gas has become an increasingly attractive option: the world has abundant gas reserves, and it’s estimated that as much as half of these reserves are substantially underutilised. What’s more, natural gas is considered to be the cleanest and most efficient of the three major fossils fuels (coal, crude oil and natural gas). Its combustion emits only about half the carbon dioxide of an equivalent amount of combusted coal.

Today, Sasol is providing its proven gas-to-liquids technology to gas-producing countries such as Qatar and Nigeria, allowing them to convert some of their gas reserves into a low-sulphur, low-aromatics form of synthetic diesel, gas-to-liquids (GTL) diesel.

In the context of increasing promotion of diesel as a fuel of choice, including the passenger-vehicle market, that’s big news.

Backed by five decades of operational experience, as well as comprehensive research and development in Fischer-Tropsch process technology and catalysis, Sasol has developed, and is marketing worldwide, its unique GTL technology, the Sasol Slurry Phase Distillate™ (Sasol SPD™) process.

With the intention of becoming a key player in the world’s emerging gas-to-liquids (GTL) industry, Sasol is using its proprietary Fischer-Tropsch technology and Sasol Slurry Phase Distillate™ process to convert natural gas into GTL diesel, GTL naphtha and some liquefied petroleum gas.

Why GTL? The benefits include:

l premium-grade petrochemical products, particularly a low-emission GTL diesel;

l ability to capitalise on the growing trend towards dieselisation in many markets; and

l helping gas-rich countries to diversify their energy base and improve energy security.

GTL technology comprises proven chemical processing technologies to convert natural gas into liquid fuels and related petrochemicals.

Synthesis gas – or syngas – is a blend of hydrogen and

carbon monoxide that can be used as the building block for producing more complex molecules, such as those needed to make high-quality GTL diesel. The heart of GTL technology is the conversion of synthesis gas into a waxy syncrude, a form of synthetic crude oil, through Fischer-Tropsch synthesis.

In the case of the Sasol Slurry Phase Distillate ™ (Sasol SPD™) process, Sasol uses its proprietary low-temperature Slurry Phase Fischer-Tropsch technology to convert natural gas into GTL diesel, GTL naphtha and some liquefied petroleum gas (LPG).

Naphtha – a mixture of light hydrocarbons – is used as a feedstock for producing certain chemicals. GTL naphtha is ideal as a feedstock for producing ethylene. It is also ideal for fuel-cell applications.

LPG comprises gaseous hydrocarbons or petroleum gases, predominantly propane and butane that are pressurised in liquefied form and used for heating.

Sasol Chevron and other GTL players have the potential to produce 10 per cent of the world’s diesel needs through GTL plants by 2020.

A cleaner burnGTL diesel from the Sasol SPD™ process has virtually no sulphur (less than five parts per million); a notably low aromatic content (less than 1 per cent); and a cetane number exceeding 70, significantly higher than the typical diesel rating of 45 to 55. The result? Reduced emissions of nitrous oxides, sulphur oxides, carbon monoxide, aromatics, unburnt hydrocarbons and particulates from compression-ignition engines. The higher cetane rating enables better combustion and easier starting in the cold. GTL diesel is also more efficient when comparing its use in a compression-ignition car with that of petrol in a spark-ignition counterpart.

GTL naphtha is an ideal fuel of choice for future use in fuel cell applications because it is sulphur-free and has a notably high hydrogen

content. GTL naphtha contains a high proportion of paraffinic material, which makes it ideal for use as a cracker feedstock for manufacturing solvents or polymers. l

GTL solutions for the world The innovative alternative

Above: Sasol’s Oryx gas-to-liquids plant in Qatar, the standard-bearer for a cleaner, more efficient fuel. Top: Lab testing Sasol’s high-quality, low-sulphur diesel.


tech focus by the publishers of popular mechanics a … · recarburiser coke – metallurgical...

Documents