Acid gas
An acid gas (engl. " Acid gas ") is generally a gas (or gas mixture ) which is at a solution in water an acid (or a weak acid form).
In particular, the term "acidic gas" is used synonymously for natural gas that has not yet been processed and which contains significant amounts of acidic gases . Natural gas with a significant content of the acidic gas hydrogen sulfide is, however, specifically sour gas (engl. " Sour gas ") called.
properties
Acid gases are often corrosive and caustic as well as poisonous (or in some cases even highly poisonous) and therefore pose a threat to people and the environment. In the smog disaster in London in 1952, for example, thousands of people died from the high concentration of sulfur dioxide in the air.
Examples
Examples of acidic gases are
- Carbon dioxide (forms carbonic acid and hydrogen carbonates in water)
- Sulfur dioxide (forms sulphurous acid in water)
- Hydrogen sulfide
- Hydrogen chloride (forms hydrochloric acid in water)
- Nitrogen dioxide (forms nitric acid in water)
- Hydrogen cyanide (forms hydrocyanic acid in water)
- Hydrogen bromide (forms hydrobromic acid in water)
- Selenium dioxide (forms selenium acid in water)
Emergence
The creation processes are diverse and vary depending on the gas. Acid gases can be of natural origin or they can arise as desired or undesired reaction gases in industrial processes. Sulfur dioxide is produced, for example, in the combustion of coal and heavy oil , in waste incineration plants, in brick and cement production and in iron and steel production . Selenium is used as an additive in glass production and thus selenium dioxide is released in the glass production process.
Absorption - Filtration - Leaching
Absorption - Filtration
In order to prevent the release of acidic gases in incineration plants, filtration is carried out. Many acid gases can be absorbed with the help of caustic soda .
Hydrogen sulfide leaching in natural gas
Hydrogen sulphide (along with carbon dioxide and water) is an undesirable addition to natural gas. This gas is mostly separated by amine-based gas scrubbing (mostly monoethanolamine and diethanolamine ) and converted into elemental sulfur in the Claus process . The basic amines can also be used to wash out the carbon dioxide, which also reacts slightly acidic with water in aqueous solution.