Applications of methane table. What is natural gas, what is its composition and how is it produced?

Enterprises were forced to burn liquid methane using flares, as they were unable to transfer condensate for subsequent petrochemical processing. Now they have learned how to transport it and use it in many areas of industry. At the same time, it is well stored and does not form harmful impurities during combustion.

Physical and chemical properties of methane

Methane is one of the simplest hydrocarbons. It is lighter than air, non-toxic, poorly soluble in water, and has no noticeable odor. It is believed that methane is not dangerous to humans, but there are known cases of its effects on the central and autonomic nervous system. Accumulating indoors, it becomes explosive at a concentration in the air of 4% to 17%. Therefore, to detect it by humans (without instruments), special substances that resemble the smell of gas are often added to methane. Refers to Methane exhibits weak narcotic properties, which are weakened by low solubility in water.

Based on origin as a result of compounds with various substances and chemical reactions, it is divided into:

• biogenic (organic);
• abiogenic (inorganic);
• bacterial (life activity of microorganisms);
• thermogenic (thermochemical processes).

This gas is also obtained in the laboratory by heating soda lime or anhydrous sodium hydroxide with frozen acetic acid.

Methane in the liquid state occupies a volume 600 times less than in the gaseous state. Therefore, for ease of transportation and storage, it is liquefied. Liquid methane is a colorless, odorless liquid. It retains almost all the properties of gas. liquid methane is 4.58 MPa (the minimum at which it turns into liquid).

Existence in nature

Methane is part of and is the main component of the following gases:

• natural (up to 98%);
• oil (40-90%);
• swamp (99%);
• mining (35-50%);
• mud volcanoes (more than 94%).

It is also found in the water of oceans, lakes, and seas. Present in the atmosphere of planets such as Earth, Saturn, Jupiter, Uranus, and in the surface gases of the Moon. Large quantities are found in coal seams. This makes mining in closed tunnels an explosive activity.

Natural gas liquefaction technology

Pure methane is obtained by removing other components from it: ethane, propane, butane and nitrogen. To obtain liquid methane, the gas is compressed and then cooled. The liquefaction process is carried out in cycles. At each stage, the volume will decrease up to 12 times. It turns into liquid in the last cycle. Various types of plants are used for liquefaction, including:

• throttle;
• turbine-vortex;
• turboexpanders.

The following schemes can be used:

• cascade;
• expansion.

The cascade design uses three cooling agents. In this case, the temperature of liquid methane decreases gradually. This technology requires large capital expenditures. Currently, this process has been improved and a mixture of refrigerants (ethane and propane) has been used. This scheme has become self-cooling, since these substances are obtained from liquefied natural gas. Costs have decreased slightly, but still remain high.

When using an expansion circuit, more economical centrifugal machines are used. The mixture is pre-cleaned from water and other contaminants and liquefied under pressure due to heat exchange with a cold expanded gas flow. However, this process requires more energy than with a cascade scheme (25-35%). But at the same time, capital costs for compressors and equipment operation are saved.

The temperature of liquid methane obtained as a result of the process described above averages 162 degrees.

Application of methane

The scope of application of methane, both in gaseous and liquid states, is very extensive. It is used as fuel, as a raw material for industry, in everyday life, as anabolic steroids for building muscle mass.

With incomplete combustion, methane produces soot, which is widely used in industry: in the production of rubber, stamp ink, shoe polish, etc. It is also used for the production of hydrocyanic and acetic acid, methanol, acetylene, ammonia, carbon disulfide, as (eternal flame) .

Liquid methane is used as a motor fuel for cars. It has an octane number 15% higher than gasoline, as well as high calorific value and anti-knock properties. According to reviews, liquid methane burns almost completely and with the correct installation of the appropriate equipment on the car, quite significant savings occur compared to gasoline (when traveling long distances).

This gas is actively used in the production of drugs that increase muscle mass. Based on it, products such as “Dianoged”, “Danabol”, “Nerobol” are produced, which are in greatest demand. It is believed that these drugs have a positive effect on the human body:

• strengthen bones;
• stimulate the formation of sexual characteristics;
• burn fat layers;
• increase endurance;
• accelerate protein synthesis.

However, it is important to remember that all drugs have side effects, so they must be taken under the supervision of a doctor.

Based on the above, we can conclude that the production of liquid methane is a very promising area of ​​modern industry.

Methane (swamp gas; CH 4) is the simplest saturated hydrocarbon. Colorless, odorless gas, melting point -182.48°. Methane ignites easily; a mixture of methane and air is explosive.

Methane is the main component of natural gas (60-99%), mine gas (35-40%), as well as various products of anaerobic decomposition of organic substances, such as swamp gas and gases from irrigation fields. Methane is formed in large quantities during the coking of coal, hydrogenation of coal and in other industrial processes.

Methane is used as a fuel for gasification, as well as for the industrial synthesis of hydrocarbons of large mol. weight. With incomplete combustion or catalytic oxidation of methane, it forms methanol (see Methyl alcohol), (see), acetylene (see). Methane is also used in the production of soot, methyl chloride, chlorbromobenzene, nitromethane, and other products.

Methane is found in intestinal gases (as a result of methane fermentation), in the blood of animals and humans.

Methane is the most inert compound from the group of paraffin hydrocarbons. Physiological methane is indifferent and can cause poisoning only in very high concentrations (due to the low solubility of methane in water and blood). However, the toxic effect of methane also occurs at lower concentrations of methane in the air. Thus, when the air contains 25-30% methane, the first signs appear (increased heart rate, increased breathing volume, impaired coordination of fine muscle movements, etc.). Higher concentrations of methane in the air cause headaches in humans. The full toxic effect of methane is manifested only at elevated pressure (2-3 atm).

First aid for acute poisoning: removing the victim from the harmful atmosphere. Hot water bottles. If there is no breathing, artificial respiration is performed immediately (before the doctor arrives), which stops only after signs of rigor mortis appear.

Chronic effects of methane. In those working in or in industries where methane and other hydrocarbons of the methane series are present in the air, noticeable changes in the side have been described (positive oculo-cardiac reflex, pronounced atropine test, ). However, chronic exposure to methane does not cause severe organic changes, although some researchers associate the occurrence of nystagmus in miners with prolonged exposure to methane.

Prevention of methane poisoning. In underground mines, methane content above 0.75 vol.% is not allowed. If the methane content increases, workers must be removed and the premises must be ventilated. The main measure to prevent methane accumulation in mines is the presence of good ventilation. For personal protection, it is necessary to use helmets with forced air supply or breathing apparatus equipped with an air supply.

Natural gas is used by gas water heaters and boilers for heating country houses, cottages, and dachas. Autonomous heating with gas is a profitable alternative, since accidents on central heating mains are not scary. Gas boilers will effectively heat a two-story cottage in just 15-30 minutes.
In the central heating system, natural gas is supplied to boiler houses and heating plants, where it is also used to generate heat, hot water supply and generate electricity in gas turbine units. The resulting heat (water for heating) and hot water are supplied through central pipelines to consumer homes.

Methane molecule

What properties does natural gas have, what do you need to know about it?

Natural gas and its properties.

The main component of natural gas is methane. Methane is a hydrocarbon gas, meaning it contains molecules of carbon and hydrogen. The hydrocarbon formula is as follows:

CnH 2 n+2, methane CH 4.

Natural gas contains up to 97% methane, the remaining 3-4% includes hydrogen sulfide (H 2 S), oxygen O 2, etc. The presence of these components reduces the thermal properties of methane.

Characteristics of methane

Methane is a colorless, non-toxic, odorless and tasteless gas. The specific gravity of methane is 0.717 kilograms per normal cubic meter (0.717 kg/Nm3). Normal conditions are air temperature = 0C (273.2 K) and pressure 101325 kPa. Standard conditions are air temperature = 20C and pressure 101325 kPa.

At a temperature of 111 K (-161 C) and atmospheric pressure, methane turns into liquid and decreases in volume by 600 times!

The higher calorific value of methane is 9510 kcal/nm 3 . The lower calorific value of methane is 8570 kcal/Nm3 (35880 kJ). This phenomenon is justified by the fact that part of the heat is lost to convert water into steam (latent heat of vaporization).

Impact of methane on human health

Methane is an asphyxiating gas, not poisonous. The permissible gas content, where installation crews and builders can work, should be no more than 300 milligrams per cubic meter.

Methane displaces oxygen in the air, meaning oxygen will be less than 21%. At the same time, the person begins to get tired and become “drunk”; (narcotic effect). When in a polluted environment, a person experiences oxygen starvation and behaves inappropriately.

If you feel gas in a room where a person is feeling unwell, you urgently need to take him out into fresh air.

Methane mixed with air in the range of its content from 5 to 15% forms an explosive mixture.

Chemical properties of methane

In methane, 75% by weight is carbon and 25% is hydrogen. The combustion of methane in air proceeds according to the following equation (ideal formula for the chemical process):

CH 4 +2O 2 +7.52N 2 =CO 2 +2H 2 O+7.52N 2 +Q,

where O 2 oxygen; N 2 nitrogen; CO 2 carbon dioxide; H 2 O water; Q is the heat released during combustion.

Air contains 21% oxygen and 79% nitrogen, and its amount for combustion is equal to the theoretically required amount. However, in practice, it is not always possible to achieve an ideal combustion process.

The table shows methane density at different temperatures, including the density of this gas under normal conditions (at 0°C). Its thermophysical properties and characteristics of other methane gases are also given.

The following are presented thermophysical properties of methane gases: coefficient of thermal conductivity λ , η , Prandtl number Pr, kinematic viscosity ν , mass specific heat capacity C p, heat capacity ratio (adiabatic exponent) k, thermal diffusivity coefficient a and density of methane gases ρ . The properties of gases are given at normal atmospheric pressure depending on temperature - in the range from 0 to 600 ° C.

Methane gases include hydrocarbons with gross formula C n H 2n+2 such as: methane CH 4, ethane C 2 H 6, butane C 4 H 10, pentane C 5 H 12, hexane C 6 H 14, heptane C 7 H 16, octane C 8 H 18. They are also called the methane homologous series.

Density of methane gases as their temperature increases, it decreases due to thermal expansion of the gas. This nature of the dependence of density on temperature is also typical. It should also be noted that the density of methane gases increases as the number of carbon and hydrogen atoms in the gas molecule increases (numbers n in the formula C n H 2n+2).

The lightest gas considered in the table is methane - Methane density under normal conditions is 0.7168 kg/m3. Methane expands when heated and becomes less dense. So, for example, at temperatures 0°C and 600°C, the density of methane differs by approximately 3 times.

Thermal conductivity of methane gases decreases with increasing number n in the formula C n H 2n+2. Under normal conditions, it varies in the range from 0.0098 to 0.0307 W/(m deg). According to the data in the table it follows that Gases such as methane have the highest thermal conductivity.— its thermal conductivity coefficient, for example at 0°C, is equal to 0.0307 W/(m deg).

The lowest thermal conductivity (0.0098 W/(m deg) at 0°C) is characteristic of octane gas. It should be noted that when methane gases are heated, their thermal conductivity increases.

The specific mass heat capacity of gases included in the homologous series of methane increases when heated. Their properties such as viscosity and thermal diffusivity also increase in value.

Natural gas is gaseous hydrocarbons formed in the bowels of the earth. It is classified as a mineral, and its components are used as fuel.

Properties and composition of natural gas

Classification of natural gases

There are only 3 groups:

• The first of them is almost eliminating the content of hydrocarbons with more than two carbon compounds, the so-called dry gases, obtained exclusively in fields intended only for gas production.
• The second is gases produced simultaneously with primary raw materials. These are dry, liquefied gases and gas gasoline mixed with each other.
• The third group includes gases consisting of dry gas and a significant amount of heavy hydrocarbons, of which gasoline, naphtha and kerosene are isolated. In addition, the composition contains a small amount of other substances. These substances are extracted from gas condensate fields.

Properties of constituent substances

The first four members of the homologous series under normal conditions are flammable gases that are colorless and odorless, explosive and flammable:

Methane

The first substance of the alkanes series is the most resistant to temperatures. It is slightly soluble in water and lighter than air. The combustion of methane in the air is marked by the appearance of a blue flame. The most powerful explosion occurs when one volume of methane is mixed with ten volumes of air. At other volumetric ratios, an explosion also occurs, but with less force. In addition, a person may suffer irreparable harm if they inhale high concentrations of gas.

Methane can be in a solid aggregate state in the form of gas hydrates.

Application:

It is used as industrial fuel and raw material. Methane is used to produce a number of important products - hydrogen, freons, formic acid, nitromethane and many other substances. To produce methyl chloride and its homologous compounds, methane is chlorinated. Incomplete combustion of methane produces finely dispersed carbon:

CH4 + O2 = C + 2H2O

Formaldehyde appears through an oxidation reaction, and when reacting with sulfur, carbon disulfide appears.

CH4 + H2O -> CO+ 3H2

Used for binding hydrocarbons, alcohols, aldehydes and other substances. Methane is actively used as a fuel for vehicles.

Ethane

A limiting hydrocarbon, C2H6, is a colorless substance in the gaseous state that produces little light when burned. It dissolves in alcohol in a ratio of 3:2, as they say, “like in like,” but is almost insoluble in water. At temperatures above 600° C, in the absence of a reaction accelerator, ethane decomposes into ethylene and hydrogen:

CH4 + H2O -> CO+ 3H2

Ethane is not used in the fuel industry; the main purpose of its use in industry is to produce ethylene.

Propane

This gas is poorly soluble in water and is a widely used fuel. It produces a lot of heat when burned and is practical to use. Propane is a by-product of the cracking process in the oil industry.

Butane

It has low toxicity, a specific odor, has intoxicating properties; inhalation of butane causes asphyxia and cardiac arrhythmia, and negatively affects the nervous system. Appears during cracking of associated petroleum gas.

Application:

The undeniable advantages of propane are its low cost and ease of transportation. A propane-butane mixture is used as fuel in populated areas where natural gas is not supplied, when processing low-melting materials with small thickness, instead of acetylene. Propane is often used in the procurement of raw materials and processing of scrap metal. In everyday life, areas of necessity include space heating and cooking on gas stoves.

In addition to saturated alkanes, natural gas includes:

Nitrogen

Nitrogen consists of two isotopes 14A and 15A, and is used to maintain pressure in wells during drilling. To obtain nitrogen, air is liquefied and separated by distillation; this element makes up 78% of the air composition. It is mainly used to produce ammonia, from which nitric acid, fertilizers and explosives are obtained.

Carbon dioxide

A compound that changes at atmospheric pressure from a solid (dry ice) to a gaseous state. It is released during the breathing of living beings, and is also found in mineral springs and air. Carbon dioxide is a food additive used in fire extinguisher cylinders and air guns.

Hydrogen sulfide

A very toxic gas - the most active of the sulfur-containing compounds, and therefore very dangerous for humans due to its direct effect on the nervous system. A colorless gas under normal conditions, characterized by a sweetish taste and a disgusting odor of rotten eggs. It is highly soluble in ethanol, unlike water. Sulfur, sulfuric acid and sulfites are obtained from it.

Helium

This is a unique product that slowly accumulates in the Earth's crust. It is obtained by deep freezing gases containing helium. In the gaseous state, it is an inert gas that has no external expression. Helium is in a liquid state, also odorless and colorless, but can infect living tissues. Helium is non-toxic and cannot explode or ignite, but at high concentrations in the air it causes asphyxiation. It is used when working with metals and as a filler for balloons and airships.

Argon

Noble, non-flammable, non-toxic, without taste or color. It is produced as an escort for the separation of air into oxygen and nitrogen gas. Used to displace water and oxygen to extend the shelf life of food, it is also used in metal welding and cutting.