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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Amine gas treating | 2/3 | https://en.wikipedia.org/wiki/Amine_gas_treating | reference | science, encyclopedia | 2026-05-05T10:45:56.042709+00:00 | kb-cron |
Monoethanolamine: About 20 % for removing H2S and CO2, and about 30 % for removing only CO2, where the plant metallurgy is appropriate. Diethanolamine: About 25 to 35 % removing H2S and CO2 Methyldiethanolamine: About 30 to 55 % for removing H2S and CO2 Diglycolamine: About 40 to 50 % for removing H2S and CO2 The choice of amine concentration in the circulating aqueous solution depends upon several factors, involving the composition of the feed gas natural gas or petroleum refinery by-product gases that contain relatively low concentrations of both H2S and CO2 or whether the unit is treating gases with a high percentage of CO2 such as the offgas from the steam reforming process used in ammonia production or the flue gases from power plants. Both H2S and CO2 are acid gases and hence corrosive to unprotected carbon steel. Their corrosiveness are greatly enhanced in the presence of moisture. However, in an amine treating unit, CO2 is a stronger acid than H2S. Furthermore hydrogen sulfide can form a passivating film of iron sulfide that may act to protect the steel. When treating gases with a high percentage of CO2, control of the CO2 loading in the amine is important to protect carbon steel from corrosion. Higher amine concentrations will have lower loading compared to lower concentrations at the same circulation rate. Another factor involved in choosing the amine concentration is the relative solubility of H2S and CO2 in the selected amine. The choice of the type of amine will affect the required circulation rate of amine solution, the energy consumption for the regeneration and the ability to selectively remove either H2S alone or CO2 alone if desired. For more information about selecting the amine concentration, the reader is referred to Kohl and Nielsen's book.
=== MEA and DEA === MEA and DEA are primary and secondary amines. They are very reactive and can effectively remove a high volume of gas due to a high reaction rate. However, due to stoichiometry, the loading capacity is limited to 0.55 mol CO2 per mole of amine. MEA and DEA also require a large amount of energy to strip the CO2 during regeneration, which can be up to 70% of total operating costs. They are also more corrosive and chemically unstable compared to other amines if the concentration is excessive.
=== Other amines ===
Piperazines have been proposed for carbon capture and storage (CCS) because piperazine is very efficient at CO2 removal. The capabilities of piperazine are within the bounds of and thus favored for carbon capture. Piperazine can be thermally regenerated through multi-stage flash distillation and other methods after being used in operating temperatures up to 150 °C and recycled back into the absorption process, providing for higher overall energy performance in amine gas treating processes. Pilot plant studies have been conducted.
== Uses == In oil refineries, that stripped gas is mostly H2S, much of which often comes from a sulfur-removing process called hydrodesulfurization. This H2S-rich stripped gas stream is then usually routed into a Claus process to convert it into elemental sulfur. In fact, the vast majority of the 64,000,000 tonnes (63,000,000 long tons; 71,000,000 short tons) of sulfur produced worldwide in 2005 was byproduct sulfur from refineries and other hydrocarbon processing plants. Another sulfur-removing process is the WSA process which recovers sulfur in any form as concentrated sulfuric acid. In some plants, more than one amine absorber unit may share a common regenerator unit. The current emphasis on removing CO2 from the flue gases emitted by fossil fuel power plants has led to much interest in using amines for removing CO2 (see also: carbon capture and storage and conventional coal-fired power plant). In the specific case of the industrial synthesis of ammonia, for the steam reforming process of hydrocarbons to produce gaseous hydrogen, amine treating is one of the commonly used processes for removing excess carbon dioxide in the final purification of the gaseous hydrogen. In the biogas production it is sometimes necessary to remove carbon dioxide from the biogas to make it comparable with natural gas. The removal of the sometimes high content of hydrogen sulfide is necessary to prevent corrosion of metallic parts after burning the bio gas.
=== Carbon capture and storage === Amines are used to remove CO2 in various areas ranging from natural gas production to the food and beverage industry, and have been since 1930. There are multiple classifications of amines, each of which has different characteristics relevant to CO2 capture. For example, monoethanolamine (MEA) reacts strongly with CO2 and has a fast reaction time and an ability to remove high percentages of CO2, even at low CO2 concentrations. Typically, monoethanolamine (MEA) can capture 85% to 90% of the CO2 from the flue gas of a coal-fired plant, which is one of the most effective solvent to capture CO2. Challenges of carbon capture using amine include: