Petrochemical

1 - Site categories of a petrochemical plant

  • onsites → prcoess units

  • offsites → supporting units

2 - Raw materials and energy

Raw materials are categorised into organic and inorganic.

Inorganic raw materials → non-carbon containing materials such as oxygen, water and minerals

Organic raw materials → fossil fuels and biomass (carbon containing materials)

3 - Early uses of petroleum

→ pioneers bought it from Native Americans for medicinal uses (Seneca oil and Genesee oil)

→ petroleum lamps as a source of light for the Prague, Czech Republic

→ modern petroleum industry began in 185 where kerosene was the chief finished product

→ as a source of lamp fuels for oil lamps

→ applicable to automobiles, trucks, tractors and airplanes during the development of gasoline engine (late 19th century)

4 - Modern uses of petroleum

→ motive power

→ lubrication

→ synthetic products

→ drugs

→ dyes

→ high value products (nylon, PVC, polyethene)

5 - Environmental problems associated with the usage and generation of petroleum

→ air pollution in industrialised countries

→ polluted water bodies from oil spills from tankers and offshore wells

6 - Formation of crude oil (petroleum)

→ decayed plant and animals remains buried under thick layers of rocks 600 million years ago

→ high organic carbon content of petroleum mostly comes from the small microscopic planktons from plant and animals remains

→ largest known reserves are located in the Middle East

7 - Obtaining petroleum

→ petroleum are usually found subterranean (sub-surface of Earth = deep underground) where petroleum must be extracted by means of wells.

→ before wells are built, exploratory wells are used to find suitable sites for wells.

→ to reduce the number of exploratory wells drilled, scientific methods are used to find the most promising sites.

→ scientific / sensitive instrument such as:

  1. Gravimeter → an instrument to register small movement by gravitational pulls.

  2. Magnetometer → measures the change in magnetic field (non-porous = non-magnetic / rocks containing organic materials = magnetic)

  3. Seismograph → seismic echoes are measured and analysed to determine whether there are crude oil deposits in the ground. (geophones and receivers)

are used to find subsurface rock formations that holds crude oils.

→ petroleum from new wells will come to the surface by its own pressure

→ crude oil must be pump out or forced to the surface by injecting water, gas or air into the deposits.

8 - Four principle fossil fuels resources

  1. Oil shale = fine grain sedimentary rocks with high carbon content → contains solid combustible materials (kerogen) → valuable due to its abundance → not an important source of energy due to its expensive harvesting costs.

  1. Coal = progressive degeneration of organic sediments known as peat → carbon-rich rocks → different types of coal (peat = 50% , Lignite = 70 -80%, Bituminous coal = 80 - 90%, Anthracite coal =more than 90%) → accumulation of decaying plants with the absence of oxygen turns into peat → peat under high temperature and pressure causes sand and mud to convert into sandstone and shale. → coals is usually created from decaying land plants that grows in swampy regions and other wetlands environment → sulfur present in coals results in sulphur dioxide when burnt causes sulphuric acid rains that corrodes natural limestone structures

  1. Crude oil and natural gas = fats and biomolecules found in dead marine animals and aquatic plants buried under sediments with high pressures

9 - Different components of crude oil

→ dissolved liquefied petroleum gases

→ napthla

→ kerosene

→ diesel

9a - Chemical composition of crude oil (varies from different locations)

→ 83-87% carbon atoms

→ 11 -15% hydrogen atoms

→ 1-6% sulfur atoms

9a (i) - Paraffin

→ saturated chain of hydrocarbons

→ carbon atoms connected by single bond where other bonds are saturated with hydrogens.

9a (ii) - Napthenes

→ saturated carbon rings

→ cyclo-alkanes

→ all bonds are saturated with hydrogen

9a (iii) - Olefins

→ usually not found in crude oil

→ formed during processing of crude oil

→ at least 2 carbon atoms connected by double bond (alkene)

9b - Types of crude oil

  • sour crude → crude oil with high content in sulphur

  • sweet crude → crude oil with minimal sulphur content

9c - Chemcial composition (varies from different location)

→ 80-95% methane

→ 15-20% ethane and propane

9d - Formation of natural gas

→ fats and other biomolecules found in dead marine creatures and aquatic plants buried with sediment

→ organic matter deposited with sediment gets heated up over long periods under high pressure

→ compositions of deposited organic matter changes which eventually turns into natural gas

10 - 4 general conditions that leads to the generation of different types of fossil fuels

  1. Organic matter

  2. Temperature

  3. Time

  4. Pressure conditions

11 - Types of operation in typical oil refinery

  1. Volatile products → liquefied petroleum gas → light naphtha

  2. Light distillates → gasoline → heavy naphtha → kerosene and jet fuels

  3. Middle distillates → automotive fuels → heating oils → gas oils

  4. Fuel oils → marine diesel → bunker fuels

  5. Lubricating oils → motor oils → machine oils

  6. Waxes → food and paper coating grade → pharmaceutical grade

  7. Bitumens → Asphalt → Coke

11a - Objectives of oil refining

  1. production of fuels for transportation, power generation and heating purposes

  2. production of raw materials, especially for the chemical and petrochemical industry

11b - Steps of crude refining

  1. Desalting and dehydration → water, inorganic salts and water soluble trace metals are removed → helps to prevent corrosion, plugging and fouling of equipment and poisoning of catalysts of downstream equipment → desalting : removal of inorganic salts content in crude oil → dehydration : removal of moisture content in crude oil

  2. Fractional distillation → crude oil is separated into 7 different categories from different boiling points. → crude oil can be separated by chemical and physical processes.

11c - Purposes of complex set of processes in oil refinery

→ differences between the properties of crude oil → requirements in the market

11d - Purpose of extensive processing of crude oil

→ obtain products with satisfactory performance especially for fuels in transport sectors

→ meet environmental requirements