Activated MDEA

The original hot carbonate process developed by the U.S. Bureau of Mines was found to be corrosive to carbon steel (55). Various additives have been used in order to improve the mass transfer rate as well as to inhibit corrosion. Vetrocoke, Carsol, Catacarb, Benfteld, and Lurgi processes are all activated carbonate processes. Improvements in additives and optimization of operation have made activated carbonate processes competitive with activated MDEA and nonaqueous solvent based systems. Typical energy requirements are given in Table 9. 

MEA with inhibitors potassium carbonate potassium carbonate and regenerator(s) activated MDEA and regenerator(s)... 

Activated MDEA A version of the MDEA process for scmbbing acid gases from gas streams, in which the aqueous MDEA solution is regenerated by flashing rather than by stripping. Developed by BASF, Germany in 1971, with the Ralph M. Parsons Co. becoming the sole licensor in most of the Western Hemisphere in 1982. The process is now operated in Europe, Canada, and the United States. 

MDEA [Methyl diethanolamine] A general name for processes using methyl diethanolamine for absorbing hydrogen sulfide and carbon dioxide from other gases. See also Activated MDEA. 

The cooled process gas that leaves the Syngas Scrubber is fed to the Amine unit. The amine unit consists of an absorption-stripping system plus associated equipment. In this system a circulating amine stream (activated MDEA - or Methyl Diethanolamine) absorbs the C02 in the C02 Absorber. The amine is regenerated in the C02 Stripper with the C02 being recycled to the compressor. 

Elf Activated MDEA An improved MDEA process for removing carbon dioxide from natural gas rich in hydrogen sulfide. The activator is a proprietary secondary amine that accelerates the reaction between the MDEA and the carbon dioxide. Developed by TotalFinaElf and IFP in the 1990s for use in the Lacq gasfield. 

Hybrisol [Hybrid solvent] A process for removing hydrogen sulfide from natural gases. Based on the Elf Activated MDEA process, but using added methanol to improve the removal of mercaptans and COS. 

In 1990 the new solvent and regeneration system were tested on an existing DEA unit at Lacq, which was then converted into the then-called Elf Activated MDEA process [3,4]. This process was also used in several other locations offshore North Sea such as in Sleipner Vest for CO2 removal and Elgin Franklin for controlled CO2 removal. Different activators have been selected and patented to suit each specific case of treatment total or partial, controlled CO2 removal with or without H2S. 

The performance of the Elf Activated MDEA is closely related to site-specific treatment conditions, notably feed gas composition and treated gas specifications. Belo v are some practical mles-of-thumb to highlight the general interest of regeneration by flash [5] ... 

The overall energy consumption of the Activated MDEA unit increases as the treated gas specification becomes more stringent, since the amount of lean totally regenerated amine from the thermal regeneration increases. In some C02-only cases, as mentioned above, it may even be possible to completely eliminate the thermal regenerator. 

As a consequence of the above attributes the Elf Activated MDEA process will be well adapted to the treatment of high pressure and very sour gases where the advantages of flash procured regeneration will be maximized. 

Case Study of the Use of Activated MDEA for Treatment of Very Sour Gas... 

Figure 10.5 Design of the amine units using the Elf Activated MDEA process.

Here we examine the combination of the well-established Elf Activated MDEA process from Total with a new pre-extraction technique under development by IFF. 

The proposed overall process flow-scheme for the treatment of very sour gases (i.e., with an acid gas content above 20%) with re-injection of the separated acid gases to a disposal reservoir incorporates a special patented H2S pre-extraction step upstream of the Activated M DEA acid gas removal process. In this upstream step [10], called SPREX, a substantial amount of the H2S and some of the CO2 are pre-removed from the wet raw gas as a pumpable liquid stream. This liquid will essentially contain by solubility all the water of saturation that comes with the inlet raw gas. It will also contain some of the incoming hydrocarbons. Figure 10.6 depicts a process flow diagram of this special pre-extraction and Activated MDEA combination process. 

To be truly competitive, the removal of the acid gas components H2S and CO2, be it trim or bulk, complete or partial, requires the optimum choice of an activator together with a carefully crafted know-how in solvent absorption/regeneration process design. The Elf Activated MDEA process developed by Total is probably the most cost-effective solution today to meet the widest range of applications from complete CO2 removal to bulk H2S and/or CO2 removal even for acid gas re-injection projects. The historical R D efforts of Elf Aquitaine coupled with current resources of Total allows this MDEA process to be credited with the most significant know-how back-up technology base on the market today. 

The upstream acid gas pre-extraction technique from IFF, called SFREX, offers a synergistic combination with the Elf Activated MDEA process in most applications for bulk H2S rich acid gas disposal projects. The substantial reduction of the acid gas removal and re-compression loads afforded by the SFREX step coupled with energy efficient flash procured Activated MDEA process achieves sour gas purification with bulk acid gas disposal very cost-effectively. 

Elf Activated MDEA (1994) An important improvement in natural gas sweetening processes. 19th World Gas Conference, Milan. 

Elgue, J., Peytavy, J.L. and Lallemand, F. (1995) The Elf Activated MDEA process new developments and industrial results. Paper presented at the International Gas Research Conference, Cannes, 1995. 

Blended amine solvents are proposed to combine the advantages of each component. The optimal recipe typically comprises a principal solvent with high net CO2 capacity and an activator exhibiting fast reaction kinetics to improve the efficiency of both the absorption and regeneration processes. A successful example is activated MDEA (aMDEA) developed by BASF [16], which presents the merits of moderate energy requirement, excellent chemici stability and improved reactivity. In this work, we investigate two additional blended solvent systems AMP+PZ and DMAE+PZ. 

Figure 2. Coirqjarison CO2 capture efficiency for the model calculations (red squares) and experiments (blue diamonds). MDEA solid fill, activated MDEA no fill. Influence of the stripper pressure with a feed gas to the absorber containing 8.4 bar CO2 (top) and influence of the CO2 feed pressure at 2 bar stripper pressure (bottom). Earlier published in [1].

Hefner, W., Y. Ide, and D. W. Stanbridge. 1984. Recent Developments in the BASF Activated MDEA Process, American Institute of Chemical Engineers National Meeting. 

W. Gerhardt and W. Hefner, BASF s Activated MDEA—A Flexible Process to Meet Specific Plant Conditions, AIChE Ammonia Safety Symposium (1988). 

The BASF Activated MDEA process employs a 2.5 to 4.5 M MDEA solution containing 0.1 to 0.4 M monomethyhnonoethanolaniine or up to 0.8 M piperazine as absorption activa-... 

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