Combustible gases: names, properties and applications

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Combustible gases are substances with a low calorific value. This is the main component of gaseous fuel, which is used to supply cities with gas, in industry and other areas of life. The physico-chemical characteristics of such gases depend on the presence of non-combustible components and harmful impurities in their composition.

Types and origin of combustible gases

Combustible gases contain methane, propane, butane, ethane, hydrogen and carbon monoxide, sometimes with impurities of hexane and pentane. They are obtained in two ways - from natural deposits and artificially. Gases of natural origin - fuel, the result of a natural biochemical process of decomposition of organic matter. Most of the deposits are located at a depth of less than 1.5 km and consist mainly of methane with small admixtures of propane, butane and ethane. As the depth of occurrence increases, the percentage of impurities increases. Produced from natural deposits or as associated gases of oil fields.

Most often, natural gas deposits are concentrated in sedimentary rocks (sandstones, pebbles). The covering and underlying layers are dense clayey rocks. The soles are mainly oil and water. Artificial - combustiblegases obtained as a result of thermal processing of various types of solid fuels (coke, etc.) and derivative products of oil refining.

The main component of natural gases produced in dry fields is methane with small amounts of propane, butane and ethane. Natural gas is characterized by a constant composition and belongs to the dry gas category. The composition of the gas obtained during oil refining and from mixed gas-oil deposits is not constant and depends on the value of the gas factor, the nature of the oil, and the conditions for the separation of oil and gas mixtures. It includes a significant amount of propane, butane, ethane, as well as other light and heavy hydrocarbons contained in oil, up to kerosene and gasoline fractions.

Extraction of combustible natural gases is to extract it from the bowels, collect, remove excess moisture and prepare for transportation to the consumer. The peculiarity of gas production is that at all stages from the reservoir to the end user, the entire process is sealed.

Combustible gases and their properties

Heating capacity is the maximum temperature released during the complete combustion of dry gas in a theoretically required amount of air. In this case, the released heat is spent on heating the combustion products. For methane, this parameter in °С is 2043, butane - 2118, propane - 2110.

Ignition temperature - the lowest temperature at which a spontaneous ignition process occurs without exposure to an external source, spark or flame, due to the heat released by the gas particles. ThisThis parameter is especially important for determining the permissible surface temperature of devices used in hazardous areas, which must not exceed the ignition temperature. For such equipment, a temperature class is assigned.

Flash point is the lowest temperature at which enough vapor is released (at the surface of a liquid) to ignite from the smallest flame. This property should not be generalized to flash point, as these parameters can vary greatly.

Gas/steam density. It is determined in comparison with air, whose density is equal to 1. The density of gas 1 - falls. For example, for methane this indicator is 0.55.

Flammable gas hazard

Combustible gases pose a danger in three of their properties:

1. Flammability. There is a risk of fire due to uncontrolled gas ignition;
2. Toxicity. Risk of poisoning by gas or combustion products (carbon monoxide);
3. Suffocation due to lack of oxygen, which can be replaced by another gas.

Combustion is a chemical reaction that involves oxygen. In this case, energy is released in the form of heat, flame. The flammable substance is a gas. The process of gas combustion is possible in the presence of three factors:

• Ignition source.
• Combustible gases.
• Oxygen.

The goal of fire protection is to eliminate at least one of the factors.

Methane

It is a colorless, odorless, light, flammable gas. Non-toxic. Methane makes up 98% of all natural gases. It is considered the main one that determines the properties of natural gas. It is 75% carbon and 25% hydrogen. Mass cube. meters - 0, 717 kg. It liquefies at a temperature of 111 K, while its volume decreases by 600 times. Low reactivity.

Propane

Propane gas is a flammable gas, colorless and odorless. It is more reactive than methane. The content in natural gas is 0.1-11% by mass. Up to 20% in associated gases from mixed gas and oil fields, up to 80% in solid fuel processing products (lignite and black coal, coal tar). Propane gas is used in various reactions to produce ethylene, propylene, lower olefins, lower alcohols, acetone, formic and propionic acid, nitroparaffins.

Bhutan

Combustible gas without color, with a peculiar smell. Butane gas is easily compressible and volatile. Contained in petroleum gas up to 12% by volume. They will also be obtained as a result of cracking of petroleum fractions and in the laboratory by the Wurtz reaction. Freezing point -138 oC. Like all hydrocarbon gases, it is flammable. Harmful to the nervous system, if inhaled causes dysfunction of the respiratory apparatus. Butane (gas) has narcotic properties.

Ethan

Ethane is a colorless and odorless gas. representative of hydrocarbons. Dehydrogenation at 550-650⁰ С leads to ethylene, over 800^{0 С leads to acetylene. Contained in natural and associated gases up to 10%. It is distinguished by low-temperature distillation. Significant volumes of ethane are released during oil cracking. Under laboratory conditions, it is obtained by the Wurtz reaction. It is the main raw material for the production of vinyl chloride and ethylene.}

Hydrogen

Transparent odorless gas. Non-toxic, 14.5 times lighter than air. Hydrogen is similar in appearance to air. It is highly reactive, has wide flammability limits, and is highly explosive. Included in almost all organic compounds. The most difficult gas to compress. Free hydrogen is extremely rare in nature, but it is very common in the form of compounds.

Carbon monoxide

Colorless gas, odorless and tasteless. Weight 1 cu. m - 1, 25 kg. It is found in high-calorie gases along with methane and other hydrocarbons. Increasing the proportion of carbon monoxide in the combustible gas lowers the calorific value. Has a toxic effect on the human body.

Use of combustible gases

Combustible gases have a high calorific value, and therefore are a highly economical energy fuel. Widely used for domestic needs, power plants, metallurgy, glass, cement and food industries, as automotive fuel, in the production of building materials.

The use of combustible gases as raw materials for the production of such organic compounds as formaldehyde, methyl alcohol, acetic acid, acetone, acetaldehyde, is due to the presence intheir composition of hydrocarbons. Methane, as the main component of combustible natural gases, is widely used for the production of various organic products. To obtain ammonia and various kinds of alcohols, synthesis gas is used - a product of the conversion of methane with oxygen or water vapor. Pyrolysis and dehydrogenation of methane produces acetylene, along with hydrogen and soot. Hydrogen, in turn, is used to synthesize ammonia. Combustible gases, primarily ethane, are used to produce ethylene and propylene, which are later used as raw materials for the production of plastics, artificial fibers and synthetic rubbers.

Liquefied methane is a promising type of fuel for many sectors of the national economy. The use of liquefied gases in many cases provides great economic benefits, reducing material costs for transportation and solving problems of gas supply in certain areas, and allows you to create stocks of raw materials for the needs of the chemical industry.