Amine systems are extremely corrosive due to the acid-gas concentrations and the high temperatures. It is important that all carbon steel exposed to the amine be stress-relieved after the completion of welding on the particular piece. A system fabricated from stress-relieved carbon steel for DEA solutions, as recommended, will not suffer excessive corrosion. For MEA… Read More »
Due to side reactions and/or degradation, a variety of contaminants will begin to accumulate in an amine system. The method of removing these depends on the amine involved. When MEA is used in the presence of COS and CS2, they react to form heat-stable salts. Therefore, MEA systems usually include a reclaimer, The reclaimer is… Read More »
The amine cooler is typically an air-cooled, fin-fan cooler, which lowers the lean amine temperature before it enters the absorber. The lean amine entering the absorber should be approximately 10°F warmer than the sour gas entering the absorber. Lower amine temperatures may cause the gas to cool in the absorber and thus condense hydrocarbon liquids.… Read More »
Rich/lean amine exchangers are usually shell-and-tube exchangers with the corrosive rich amine flowing through the tubes. The purpose of these exchangers is to reduce the reboiler duty by recovering some of the sensible heat from the lean amine. The flow rates and inlet temperatures are typically known. Therefore, the outlet temperatures and duty can be… Read More »
Amine-stripper overhead condensers are typically air-cooled, fin-fan exchangers. The inlet temperature to the cooler can be found using the partial pressure of the overhead steam to determine the temperature from steam tables. The cooler outlet temperature is typically 130 to 145°F depending on the ambient temperature. The reflux accumulator is a separator used to separate… Read More »
Amine strippers use heat and steam to reverse the chemical reactions with CO2 and H2S, The steam acts as a stripping gas to remove the CO2 and H2S from the liquid solution and to carry these gases to the overhead. To promote mixing of the solution and the steam, the stripper is a trayed or… Read More »
The reboiler provides the heat input to an amine stripper, which reverses the chemical reactions and drives off the acid gases. Amine reboilers may be either a kettle reboiler or an indirect fired heater. Higher the reboiler duty, the higher the overhead condenser duty, the higher the reflux ratio, and thus the lower the number… Read More »
The rich amine solution from the absorber is flashed to a separator to remove any hydrocarbons. A small percentage of acid gases will also flash when the pressure is reduced. The dissolved hydrocarbons should flash to the vapor phase and be removed. However, a small amount of hydrocarbon liquid may begin to collect in this… Read More »
The circulation rates for amine systems can be determined from the acid gas flow rates by selecting a solution concentration and an acid gas loading. The following equations can be used: For design, the following solution strengths and loadings are recommended to provide an effective system without an excess of corrosion: For the recommended concentrations… Read More »
Amine absorbers use counter-current flow through a trayed or packed tower to provide intimate mixing between the amine solution and the sour gas. Typically, small diameter towers use stainless steel packing, while larger towers use stainless steel trays. For systems using the recommended solution concentrations and loadings, a tower with 20 to 24 actual trays… Read More »