Petroleum and Natural Gas: Processing and Applications
Transformation into Products Suitable for Consumption
In refineries, a series of processes are carried out that aim to separate the different components or fractions of petroleum.
Fractional Distillation
Fractional distillation involves heating the oil until it evaporates and then cooling it to obtain different fractions based on their boiling points. This is done in distillation towers (working at atmospheric pressure) or fractionation columns (under vacuum). The process begins by heating the oil in an oven at about 360°C and introducing it into the first tower. Gases, such as butane and propane, reach the top of the tower where they are extracted. The other components, like gasoline, kerosene, and diesel, are extracted at different levels according to their boiling points. The remaining liquid fraction is called atmospheric residue. Once extracted, this residue enters the vacuum tower at 400°C to be distilled again. This way, diesel is obtained at the top, and kerosene and fuel oils at different heights. At the bottom of the tower, a residue is obtained from which oils and asphalt can be extracted.
Cracking
Cracking involves the decomposition of heavier hydrocarbons (oils, fuel oils) to obtain lighter ones (gasoline). This process can be done at high temperatures and pressures, or with chemical catalysts.
Polymerization
Polymerization is the chemical process opposite to cracking. Lighter hydrocarbons (butane, propane) become heavier compounds (gasoline or diesel). The processes of cracking and polymerization are important because they allow for obtaining the product with the most market demand (gasoline) from others that are not in as much demand.
Reformation
Reformation is used to improve the characteristics of gasoline. It is done at high temperatures. The final process involves the removal of chemical impurities, such as sulfur and corrosive compounds.
Applications of Petroleum Products
- Directly: Butane and propane gas, gasoline, kerosene, diesel oil, lubricating oils, etc.
- Petrochemical Industry: Petroleum is used to obtain products with many applications, such as plastics, synthetic fibers, detergents, synthetic rubber, solvents, and paints.
Natural Gas
Natural gas is a gas composed mainly of methane, mixed with other gases such as ethane, propane, and butane. It is found in underground pockets covered with layers of waterproof material.
Extraction, Transportation, and Distribution
The formation of natural gas is similar to that of oil, so the location and extraction are the same. The gas is processed before being transported to remove impurities (dust, sand, water, etc.) and to obtain pure methane. Transportation is done with gas pipelines or liquefied natural gas (LNG) tankers. Within a country, gas is transported to distribution plants via pipelines. This is the cheaper transport system.
Methane tankers are used when the difficulty of installing pipelines is very high. These vessels carry the gas to LNG terminals and distribution plants. Because it is cheaper, the volume is reduced for transport. The gas undergoes a cooling process in several stages to obtain liquefied natural gas (LNG). To distribute the gas to consumers, a network of pipes with different pressures is required, depending on the proximity of the consumption points.
Applications
Natural gas is used in different fields:
- Industry, commerce, and residential.
- Combined-cycle power plants (using natural gas alternating with fuel oil and coal).
- Cogeneration facilities: the simultaneous production of electricity and useful heat. This more sophisticated technology reduces energy losses and allows us to provide electricity and hot water for heating.
- The petrochemical industry (as a raw material).
Gaseous Fuels
A fuel gas is able to react with oxygen from the air and release heat quickly. There are three families of gases:
- First Family: This belongs to the group of city gas and manufactured gas obtained from coal, oil, or natural gas. It is intended primarily for domestic consumption.
- Second Family: This is natural gas. It is distributed through a network of pipes.
- Third Family: These are butane and propane. They are named as such because they are distributed in cylinders or tanks in liquid form.