A refinery is a production facility composed of a group of chemical engineering unit processes
and unit operation
certain materials or converting raw material
into products of value.
Types of refineries
Different types of refineries are as follows:
* petroleum oil refinery
, which converts crude oil
motor spirit (gasoline
/petrol), diesel oil
, liquefied petroleum gas
es (LPG), kerosene
, heating fuel oil
s, hexane, lubricating oil
and petroleum coke
* Edible oil refinery
which converts cooking oil
into a product that is uniform in taste, smell and appearance, and stability;
*natural gas processing
plant, which purifies and converts raw natural gas into residential, commercial and industrial fuel gas, and also recovers natural gas liquids
(NGL) such as ethane
s and pentane
* sugar refinery
, which converts sugar
cane and sugar beets into crystallized sugar and sugar syrups;
* salt refinery
, which cleans common salt (NaCl
), produced by the solar evaporation
of sea water, followed by washing and re-crystallization
* metal refineries refining metals such as alumina
* iron refining, a stage of refining pig iron (typically grey cast iron to white cast iron), before fining
, which converts pig iron into bar iron or steel
A typical oil refinery
The image below is a schematic flow diagram
of a typical oil refinery depicting various unit processes and the flow of intermediate products between the inlet crude oil feedstock
and the final products. The diagram depicts only one of the hundreds of different configurations. It does not include any of the usual facilities providing utilities such as steam, cooling water, and electric power as well as storage tank
s for crude oil feedstock and for intermediate products and end products.
Natural gas processing plant
The image below is a schematic block flow diagram
of a typical natural gas processing plant. It shows various unit processes converting raw natural gas into gas pipelined to end users.
The block flow diagram also shows how processing of the raw natural gas yields byproduct sulfur, byproduct ethane, and natural gas liquids (NGL) propane, butanes and natural gasoline (denoted as pentanes +).
Sugar is generally produced from sugarcane
or sugar beet
s. As the global production of sugar from sugarcane is at least twice the production from sugar beets, this section focuses on sugarcane.
Sugarcane is traditionally refined into sugar in two stages. In the first stage, raw sugar is produced by the milling of harvested sugarcane. In a sugar mill, sugarcane is washed, chopped, and shredded by revolving knives. The shredded cane is mixed with water and crushed. The juices (containing 10-15 percent sucrose
) are collected and mixed with lime
to adjust pH
to 7, prevent decay into glucose
, and precipitate impurities. The lime and other suspended solids are settled out, and the clarified juice is concentrated in a multiple-effect evaporator
to make a syrup with about 60 weight percent sucrose. The syrup is further concentrated under vacuum
until it becomes supersaturated
and is then seeded with crystalline
sugar. Upon cooling, sugar crystallizes out of the syrup. Centrifuging
then separates the sugar from the remaining liquid (molasses). Raw sugar has a yellow to brown color. Sugar is sometimes consumed locally at this stage but usually undergoes further purification.
is bubbled through the cane juice subsequent to crystallization in a process known as "sulfitation." This process inhibits color forming reactions and stabilizes the sugar juices to produce “mill white” or “plantation white” sugar.
The fibrous solids, called ''bagasse'', remaining after the crushing of the shredded sugarcane are burned for fuel which helps a sugar mill to become self-sufficient in energy. Any excess bagasse can be used for animal feed, to produce paper, or burned to generate electricity for the local power grid. 275px|Sugar refinery in Arabi, Louisiana
, United States.
The second stage is often executed in heavy sugar-consuming regions such as North America
, and Japan
. In the second stage, white sugar is produced that is more than 99 percent pure sucrose
. In such refineries, raw sugar is further purified by fractional crystallization