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How petrochemicals are made
How do everyday products get made from natural gas?
What are Natural Gas Liquids?
Natural Gas Liquids, or NGLs, exist in certain natural gas deposits including the Marcellus Shale. They are made up of ethane, propane, butane and other compounds. Natural gas companies remove NGLs from natural gas to allow the residual gas, mainly methane, to be shipped by pipeline, but these NGLs have economic value as feedstock (or raw material) to produce petrochemicals or fuels. We can obtain various products from NGLs: ethane, propane, butane and some heavier ones called condensate or natural gasoline.
What is a cracker?
A cracker is a petrochemical facility that breaks down large molecules from oil and natural gas into smaller ones. Ethane is one of the valuable products that can be fed into a cracker. An ethane cracker produces basic petrochemical “building blocks”, like ethylene, many of which are the first stage in the chemicals manufacturing chain.
Very simply, the cracking process involves breaking up the carbon and hydrogen molecules and rearranging them. This is accomplished by heating the ethane to very high temperatures, greater than 800°C (1500°F), in one of the cracker’s furnaces.
The proposed Appalachia cracker would be world-scale. World-scale crackers typically produce more than a million tons of ethylene per year. As a global energy company, the Shell upstream-downstream integrated business position means that we could supply feedstock from our Marcellus Shale production. But, we could also work with other shale gas producers in the region who may be interested in supplying us with their ethane.
What are derivatives?
Derivatives are petrochemicals that are made during subsequent processing stages, using products from the cracker. For example, polyethylene is a derivative of ethylene and an important raw material for countless everyday items, from plastic bags and packaging to automotive components, cables and injection moulding.
Mono-ethylene glycol (MEG) is also derived from ethylene. End uses for MEG fall broadly into three categories: fibres (polyester, fleece fabric, upholstery, carpets, etc.), polyethylene terephthalate - PET (plastic drink and food containers, bags, etc.), and automotive products (engine coolants and anti-freeze).