Triethanolamine Triethanolamine Although asqueous triethanolamine (TEA) was the frst commercially commercially applied amine sweetening process, it has been displaced largely by either MEA or DEA. TEA is less reactie reactie with acid gases. !t has less acid gas carrying carrying capacity per olume o" solution and also cannot reduce #$% content to general pipeline specifcations. The principal apparent adantage o" TEA (and MDEA, also a tertiary amine) is that it is selectie "or hydrogen sulfde. &robably &robably this is because tertiary amines cannot cann ot undergo a direct reaction with carbon dio'ide, dio'ide, as they do with hydrogen sulfde. The selectiity is n ot signifcant, howeer, and today neither TEA nor MDEA fnd widespread application application as industrial sweetening agents. %olution concentrations The primary dierences in in the process schemes "or MEA and DEA sweetening are in solution concentrations. MEA is ordinarily used in a * to $* per cent by weight asqueous solution. +y "ar the most common concentration would be appro'imately appro'imately per cent by weight MEA. DEA is also used in the * or $* per cent by weight concentrations. The %-&A %-&A (%ociete -acionale des &etroles d Aquitaine) modifcation modifcation o" the DEA process uses a higher concentrations o" DEA. The process unit /ow scheme is conentional, but DEA solution concentration will range upward to 0* or more weight per cent DEA. This higher concentration o" DEA (because o" the higher molecular weight o" DEA) gies about the same molar ratio o" amine and water as does a to $* weight per cent MEA solution. 1se o" amines in asqueous solution, o" course, saturates the sweet gas with water apor, regardless o" whether the entering sour gas is wet or dry. dry. 2or most amine processes, this means that a dehydration step necessarily "ollows sweetening. 3ne process which oercomes this shortcoming is the use o" MEA or DEA in combination with ethylene or diethylene glycol. 4ombination o" amine and glycol will usually do an e'cellent 5ob in remoing acid gas constituents, but generally does not dehydrate as well as a conentional glycol installation. %eere corrosion problems are "requently encountered when using the glycol6amine combination so that this process is not currently in widespread use. The general process /ow /ow "or an amine sweetening plant plant is shown in 2ig. 2ig. 0.$. The process /ow scheme scheme aries little, regardless regardless o" the asqueous amine amine solution used as the sweetening agent. The primary pieces o" equipment o" concern are the absorber column and stripper column, together with the associated piping, heat e'change, and separation equipment. The sour gas containing #$% and7or and7or 43$ will nearly always always enter the plant through a scrubber (not shown) to remoe any "ree liquids and 7or entrained
solids. The sour gas then enters the bottom o" the absorber column and /ows upward though the absorber in intimate counter6current contact with the asqueous amine solutions. %weetened gas leaes the top o" the absorber and /ows to a dehydrations unit be"ore being considered ready "or sale. 2ig.0.$ 2low sheet o" basic amine process 8ean amine solution "rom the bottom o" a stripper column is pumped through an amine6amine heat e'changer and then through a water or air6cooled e'changer be"ore being introduced to the top tray o" the absorber column. The amine moes downward through the absorber counter6current to the sour gas, and absorbs acid gas constituents "rom the gas stream. 9ich amine solution /ows "rom the bottom o" the absorber through the amine6amine heat e'changer and then to the top o" the stripper column. The amine6amine heat e'changer seres as a heat conseration deice and lowers total heat requirements "or the process. A part o" the absorbed acid gases will be /ashed "rom the heater rich solution on the top tray o" the stripper. The remainder o" the rich solution /ows downward through the stripper in counter6current contact with apor generated in the reboiler. The reboiler apor (primarily steam) strips the acid gases "rom the rich solution. The acid gases are separated in a separator and sent to the /are or to processing. The condensed steam is returned to the top o" the stripper as re/u'. 9ich amine solution leaes the bottom o" the absorber at an eleated temperature due to the heat o" reaction released when acid gases react with the amine. 2or this reason heat e'change on the lean amine solution in the amine6amine e'changer does not cool it su:ciently "or many processes. The amine cooler seres lower the lean amine temperature to the **;2 range. #igher temperatures on lean amine solution will result in e'cessie amine losses through apori
) is shown in fg. 0.0. This modifcation uses two amine solutions "ed at dierent points to the absorber ? a semi6lean solution introduced at a midway point and a lean solution introduced in the conentional manner at the top o" the absorber. This process is particularly adantageous "or threating sour gases with a high acid gas content ? aboe appro'imately 0* per cent. The liquid withdrawn "rom the mid6point on the stripper is not completely stripped and is circulated to the bottom part o" the absorber, where the acid gas concentration is highest. The lean solution introduced at the top o" the absorber contacts the gas with the lowest acid gas concentration and reduces it to the specifed leel.
2ig. 0.0 2low sheet o" split6stream amine process This process modifcation oers the possibility o" signifcant saings in steam costs, particularly "or high acid gas streams. !t has the disadantage o" increasing substantially the inestment costs in the plant. !n addition, the stripper column is taller, and both the absorber and stripper are more comple'. The two lean amine streams require separate pumps and heat e'changers, together with a more complicated control system.
trietanolamina Aunque la trietanolamina acuosa (TEA) "ue el primer proceso de endul
de deshidratacin sigue necesariamente edulcorante. 1n procedimiento que supera esta defciencia es el uso de MEA o DEA en combinacin con etileno o dietilenglicol. 4ombinacin de amina y glicol suele hacer un e'celente traba5o en la eliminacin de componentes de los gases @cidos, pero en general no deshidratarse, asC como una instalacin de glicol conencional. Fraes problemas de corrosin son "recuentes cuando se utili
@cido reaccionan con la amina. &or esta ra<n intercambio de calor en la solucin de amina pobre en el intercambiador de amina6amina no en"rCa lo sufciente para muchos procesos. El en"riador de amina sire menor es la temperatura de amina pobre para el rango de ** ; 2. 8as temperaturas m@s altas en la solucin de amina pobre resultar@ en pBrdidas e'cesias de amina a traBs de la apori) se muestra en la fg. 0.0. Esta modifcacin utili