| Abstract [eng] |
Removal of carbon dioxide from gas streams is important process in many industries, which are using synthesis gas for production technically, economically and environmentally. The main CO2 abatement technology in large scale production is the absorption – desorption process, which utilizes solutions of alkanolamines used as solvents production. Today, there are many activators for removal carbon dioxide, such as piperazine (C4H10N2), N-methyldiethanolamine (MDEA), which has found widespread application in the bulk removal of carbon dioxide. The principle of such a blend of a primary or secondary (alkanol)amine and a tertiary alkanolamine is based on the relatively high rate of reaction of CO2 with the primary or secondary alkanolamine combined with the low heat of reaction of CO2 with the tertiary alkanolamine, which leads to higher rates of absorption in the absorber column and lower heats of regeneration in the stripper section. Knowledge on mass transfer related issues on one hand and thermodynamic equilibrium on the other hand is indispensable for an optimal design and operation of both an absorber and a desorber column using the piperazine activated MDEA solvent. As the aforementioned information related to this particular solvent in the literature was still rather limited, it was the incentive of this thesis to provide more insights into the absorption of carbon dioxide into compounds containing piperazine and MDEA. Although a number of amines can activate methyldiethanolamine – MDEA, piperazine is the most commonly used promoter in applications involving CO2 removal from syngas, as well as from natural gas in production. Because of its very low regeneration energy, removing CO2 using MDEA alone would be preferred, however, the reaction in solution is extremely slow and the absorption process is controlled entirely by resistance to mass transfer in the solvent phase. Piperazine is highly reactive with CO2 (about ten times faster kinetics than monoethanolamine) which greatly enhances CO2 absorption rates. Yet because only relatively small concentrations of piperazine are needed, solvent regeneration energy requirements are not much higher than for MDEA alone. |
