Макс Курдюков

Natural gas is a fossil energy source that formed deep beneath the earth's surface. Natural gas contains many different compounds. The largest component of natural gas is methane, a compound with one carbon atom and four hydrogen atoms (CH4). Natural gas also contains smaller amounts of natural gas liquids (NGLs, which are also hydrocarbon gas liquids), and nonhydrocarbon gases, such as carbon dioxide and water vapor. We use natural gas as a fuel and to make materials and chemicals.

Petroleum and natural gas formation

Millions to hundreds of millions of years ago and over long periods of time, the remains of plants and animals (such as diatoms) built up in thick layers on the earth’s surface and ocean floors, sometimes mixed with sand, silt, and calcium carbonate. Over time, these layers were buried under sand, silt, and rock. Pressure and heat changed some of this carbon and hydrogen-rich material into coal, some into oil (petroleum), and some into natural gas.

Schematic geology of natural gaz resources

In some places, natural gas moved into large cracks and spaces between layers of overlying rock. The natural gas found in these types of formations is sometimes called conventional natural gas. In other places, natural gas occurs in the tiny pores (spaces) within some formations of shale, sandstone, and other types of sedimentary rock. This natural gas is referred to as shale gas or tight gas, and it is sometimes called unconventional natural gas. Natural gas also occurs with deposits of crude oil, and this natural gas is called associated natural gas. Natural gas deposits are found on land, and some are offshore and deep under the ocean floor. A type of natural gas found in coal deposits is called coalbed methane.

Operators preparing a hole for the explosive charges used in seismic exploration

he search for natural gas begins with geologists who study the structure and processes of the earth. They locate the types of geologic formations that are likely to contain natural gas deposits.

Geologists often use seismic surveys on land and in the ocean to find the right places to drill natural gas and oil wells. Seismic surveys create and measure seismic waves in the earth to get information on the geology of rock formations. Seismic surveys on land may use a thumper truck, which has a vibrating pad that pounds the ground to create seismic waves in the underlying rock. Sometimes small amounts of explosives are used. Seismic surveys conducted in the ocean use blasts of sound that create sonic waves to explore the geology beneath the ocean floor.

If the results of seismic surveys indicate that a site has potential for producing natural gas, an exploratory well is drilled and tested. The results of the test provide information on the quality and quantity of natural gas available in the resource.

If the results from a test well show that a geologic formation has enough natural gas to produce and make a profit, one or more production (or development) wells are drilled. Natural gas wells can be drilled vertically and horizontally into natural gas-bearing formations. In conventional natural gas deposits, the natural gas generally flows easily up through wells to the surface.

In the United States and in a few other countries, natural gas is produced from shale and other types of sedimentary rock formations by forcing water, chemicals, and sand down a well under high pressure. This process, called hydraulic fracturing or fracking, and sometimes referred to as unconventional production, breaks up the formation, releases the natural gas from the rock, and allows the natural gas to flow to and up wells to the surface. At the top of the well on the surface, natural gas is put into gathering pipelines and sent to natural gas processing plants.

Natural gas withdrawn from natural gas or crude oil wells is called wet natural gas because, along with methane, it usually contains NGLs—ethane, propane, butanes, and pentanes—and water vapor. Wellhead natural gas may also contain nonhydrocarbons such as sulfur, helium, nitrogen, hydrogen sulfide, and carbon dioxide, most of which must be removed from natural gas before it is sold to consumers.

From the wellhead, natural gas is sent to processing plants where water vapor and nonhydrocarbon compounds are removed and NGL are separated from the wet gas and sold separately. Some ethane is often left in the processed natural gas. The separated NGLs are called natural gas plant liquids (NGPLs), and the processed natural gas is called dry, consumer-grade, or pipeline quality natural gas. Some wellhead natural gas is sufficiently dry and satisfies pipeline

transportation standards without processing. Chemicals called odorants are added to natural gas so that leaks in natural gas pipelines can be detected. Dry natural gas is sent through pipelines to underground storage fields or to distribution companies and then to consumers.

Propane appears as a colorless gas with a faint petroleum-like odor. It is shipped as a liquefied gas under its vapor pressure. For transportation it may be stenched. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Easily ignited. The vapors are heavier than air and a flame can flash back to the source of leak very easily. The leak may be either a liquid or vapor leak. The vapors can asphyxiate by the displacement of air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

Interactive Chemical Structure Model

of leak very easily. The leak may be either a liquid or vapor leak. The vapors can asphyxiate by the displacement of air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

Methane is a colorless odorless gas. It is also known as marsh gas or methyl hydride. It is easily ignited. The vapors are lighter than air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. It is used in making other chemicals and as a constituent of the fuel, natural gas.

Chemical Structure Depiction

Methane is a one-carbon compound in which the carbon is attached by single bonds to four hydrogen atoms. It is a colourless, odourless, non-toxic but flammable gas (b.p. -161℃). It has a role as a fossil fuel, a member of greenhouse gas and a bacterial metabolite. It is a mononuclear parent hydride, a one-carbon compound, a gas molecular entity and an alkane. It is a conjugate acid of a methanide.

Natural gas, refrigerated liquid (cryogenic liquid) appears as a flammable liquefied gaseous mixture of straight chain hydrocarbons, predominately methane.

3D formula

Pentane is a straight chain alkane consisting of 5 carbon atoms. It has a role as a non-polar solvent and a refrigerant. It is a volatile organic compound and an alkane.

N-pentane appears as a clear colorless liquid with a petroleum-like odor. Flash point 57°F. Boiling point 97°F. Less dense than water and insoluble in water. Hence floats on water. Vapors are heavier than air.

The Kingdom of Bhutan, a small, land-locked nation in Asia, located in the eastern Himalaya mountains south of China (Xizang - Tibet Autonomous Region), bordering the Indian states of Sikkim, West Bengal, Assam and Arunachal Pradesh, it is also bordered by Nepal and Bangladesh. The country controls several key Himalayan mountain passes.

Bhutan occupies an area of 38,394 km² making it somewhat smaller t

Location map of Bhutan

han Switzerland or about half the size of the US state of Indiana. Bhutan's landscape is mostly mountainous with some fertile valleys and savanna.

The country has a multiethnic population of 760,000 inhabitants (in 2015). There are three main ethnic groups in Bhutan, the Tshanglas (or Sharchop) are considered the aboriginal inhabitants of eastern Bhutan, the Ngalops, people of Tibetan origin who migrated to Bhutan, and the Lhotshampas, a group of Nepali language-speaking Bhutanese people. Official language is Dzongkha, a language closely related to Tibetan and Nepali. Capital and largest city is Thimphu.

Butane is a hydrocarbon with molecular formula C4H10. It is an alkane and found in gaseous state at room temperature.

In other words, we can define butane as a member of the paraffin hydrocarbon series (or alkane series) which has 4 carbon atoms and 10 hydrogen atoms. Butane is a saturated hydrocarbon as single bonds are found between all carbon atoms of butane.

Butane Structure

Properties of Butane

Physical properties of butane are listed below :

- Its molecular formula

is C4H10 and empirical formula is C2H5.

- Boiling point of butane is -1 to 1℃.

- It is highly flammable.

- It is gas at room temperature and atmospheric pressure.

- It is a colorless gas.

- It has an odor like gasoline.

- It can be easily liquified and liquified butane gas can be easily converted into vapor at room temperature.

- Molar mass of butane is 58.124g/mol.

- Its density is 2.48kg/m3 at 15℃.

- It is very less soluble in water. Its solubility in water is 61mg per liter at 68℉.

Chemical Properties of Butane

Chemical properties of butane are listed below:

- Reaction with oxygen – Butane reacts with oxygen and forms carbon dioxide and water vapor. Reaction is given below -

2C4H10 + 13O2 🡪 8CO2 + 10H2O + Energy

- If the amount of oxygen is limited, then it forms carbon monoxide and water vapor. Reaction is given below –

2C4H10 + 13O2 🡪 8CO2 + 10H2O

- Reaction with chlorine – Butane reacts with chlorine and forms butyl chloride and HCl. Reaction is given below –

2C4H10 + Cl2 🡪 C4H9Cl + HCl

- Reaction with iodine – Butane reacts with iodine and forms 2-iodobutane and hydrogen iodide. Reaction is given below –

2C4H10 + I2 🡪 C4H9I + HI

Production of Butane

Butane is a fossil fuel produced naturally by dead remains of the plants and animals deep inside the earth. It is found as natural gas deep inside the earth. We obtain butane by fractional distillation of crude oil. During this process we get many other products as well such as kerosene, diesel, heavy gas oil etc.

Fractional distillation is the process of separating various components of a liquid mixture on the basis of their different boiling points using a fractionating column. Fractional distillation of crude oil is also called petroleum refining.

Uses of Butane

Butane is a fossil fuel and is very useful in many fields:

- Fuel for various purposes.

- It is one of the components of LPG (Liquified petroleum gas).

- For gasoline blending.

- It is a key raw material of synthetic rubber.

- Isobutane is used in refineries.

- In steam cracking.

- In deodorants or aerosol sprays as propellant.

- As fuel in cigarette lighters.

- In air conditioning systems.

- As fuel in a butane torch .

- Fuel in camping stoves, barbecues etc. Although transportation of butane must be done very carefully.

- Butane is not a greenhouse gas and does not produce smoke on burning. It does not affect the ozone layer of the atmosphere as well. Therefore, we can say, butane is an environmentally friendly gas or fuel.

Propane appears as a colorless gas with a faint petroleum-like odor. It is shipped as a liquefied gas under its vapor pressure. For transportation it may be stenched. Contact with the unconfined liquid can cause frostbite by evaporative cooling. Easily ignited. The vapors are heavier than air and a flame can flash back to the source of leak very easily. The leak may be either a liquid or vapor leak. The vapors can asphyxiate by the displacement of air. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.

Ethane, a colourless, odourless, gaseous hydrocarbon (compound of hydrogen and carbon), belonging to the paraffin series; its chemical formula is C2H6. Ethane is structurally the simplest hydrocarbon that contains a single carbon–carbon bond. The second most important constituent of natural gas, it also occurs dissolved in petroleum oils and as a by-product of oil refinery operations and of the carbonization of coal. Ethane appears as a colorless odorless gas. It is easily ignited. The vapors are heavier than air. It can asphyxiate by the displacement of air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. Contact with the liquid may cause frostbite.

The industrial importance of ethane is based upon the ease with which it may be converted to ethylene (C2H4) and hydrogen by pyrolysis, or cracking, when passed through hot tubes. Like propane and, to a lesser extent, butane, ethane is a major raw material for the huge ethylene petrochemical industry, which produces such important products as polyethylene plastic, ethylene glycol, and ethyl alcohol.

More than 90 percent of the ethane produced in the 1960s was burned as fuel without separation from natural gas. Ethane gas can be liquefied under pressure or at reduced temperatures and thus be separated from natural gas. Unlike propane, liquid ethane is not in common use as an industrial or domestic fuel.

Floss is a special floss for cleaning plaque from between the teeth. Using a toothbrush can clean only three of the five surfaces of a person's teeth. The other two surfaces between teeth require special care because a toothbrush cannot remove plaque and food from between them. That's why tooth decay often starts therimary means of cleaning between the interdental spaces (proximal surfaces) of your teeth. It is desirable to use it after each meal. Or at least during evening brushing.

According to some studies, improper flossing can damage teeth, gums or fillings as well as dental implants.

Contraindications to Flossing

Crowns or bridges. Orthodontic microprostheses imply the use of a dental accessory superfloss, which combines the functions of the different types of this product.

Materials and types

Dental floss is made from natural silk or artificial fibers (acetate, nylon, kapron).

Floss comes in the following types:

- waxed - impregnated with wax, making it easier to penetrate narrow gaps

- Non-waxed - cleans better

By cross section, there are two types of floss

- round - for wide gaps

- flat - for narrow gaps

- Bulky - increases in diameter (swells) when in contact with moisture (saliva)

- ribbon-shaped - for wide gaps (diastemas and trimesters)

Flossers are also differentiated by the composition of the floss

- Impregnated. These are flosses that are impregnated with special compounds. These can be simple flavorings designed to freshen the breath, antiseptics to ensure the destruction of bacteria, or fluoride-containing ingredients that ensure the strengthening of dental tissues and prevent the development of tooth decay. Menthol floss leaves a pleasant taste and feeling of freshness in the mouth. Floss with fluoride strengthens enamel and prevents tooth decay. Impregnation with red pepper extract (capsaicin) is designed to improve blood circulation in the gums. Flossing can cut the gum, leaving a hard-to-heal wound, so you need to be especially careful with pepper impregnation.

- Unimpregnated. No additional chemical compounds are used as part of the fiber.

Most floss comes in small rolls with a built-in cutter in the form of a protruding tongue (like a needle on an all-metal button, but at an acute angle and with a rounded end).

Method of application

The thread with a length of 20-30 cm is rolled on the middle fingers of the hand and pulled on the right thumb and the left index finger. In taut condition the floss is introduced into the interdental space, gently lowered to the contact with the gum (without damaging the gum), pressed to the contact surface of the tooth and in this position make 6-7 movements in the anteroposterior direction to the incisal edge. The thread is moved moderately so as not to traumatize the gingiva. All teeth are passed in this way. If you have gum disease, the doctor may recommend cleaning the interdental spaces with a special brush.