A low energy aqueous ammonia CO2 capture process

Jozsef Gaspar, Muhammad Waseem Arshad, Eirik Ask Blaker, Birger Langseth, Tord Hansen, Kaj Thomsen, Nicolas von Solms, Philip Loldrup Fosbøl

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Abstract

The most pressing challenges regarding the use of ammonia for CO2 capture are the precipitation limitation and the energy penalty of solvent regeneration. Precipitation-free operation is a vital task since solids may cause the shutdown of the plant. Precipitation and slurry formation can be avoided by increasing temperature and L/G ratio but this leads to higher heat consumption, jeopardizing the economic feasibility. Here we developed, investigated, and optimized a novel CO2 capture process design using aqueous ammonia as solvent. The proposed configuration replaces the traditional stripper for solvent based CO2 capture with a thermal decomposition reactor. The overall energy penalty is reduced at the expense of introducing a solid handling section which consists of a saturation reactor, a crystallizer and a belt filter. The feasibility of the present approach is demonstrated by simulation. Flow-sheet calculations are performed in Aspen Plus using the extended UNIQUAC thermodynamic model for vapor-liquid-solid equilibria and for thermal properties calculation of the CO2 -NH3-H2O system. The simulation results show that the specific regeneration duty of the novel capture alternative is comparable with existing aqueous ammonia CO2 capture processes. Moreover, the thermal reactor can operate at 1 bar and 86 °C, therefore the NH3 regeneration temperature is reduced by approximately 50 qC. The integration of low- and mid- temperature waste heat becomes possible which can greatly improve the economics of the process. The present capture alternative is especially convenient for power plants but is also beneficial for the cement, steel and aluminum industry. Special attention is given to the ammonia slip prediction. The calculations substantiate that the slip above the absorber is 0.1 mol % after washing with the rich solution and it reduces below 100 ppm by washing with low temperature water.
Original languageEnglish
JournalEnergy Procedia
Volume63
Pages (from-to)614 – 623
ISSN1876-6102
DOIs
Publication statusPublished - 2014
Event12th International Conference on Greenhouse Gas Technologies (GHGT-12) - University of Texas at Austin, Austin, TX, United States
Duration: 5 Oct 20149 Oct 2014
Conference number: 12
http://www.ghgt.info/index.php/Content-GHGT12/ghgt-12-overview.html

Conference

Conference12th International Conference on Greenhouse Gas Technologies (GHGT-12)
Number12
LocationUniversity of Texas at Austin
CountryUnited States
CityAustin, TX
Period05/10/201409/10/2014
Internet address

Bibliographical note

© 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Keywords

  • CO2 post-combustion capture simulation and optimization
  • Aquoeus ammonia
  • Slurry and solid formation
  • Low energy process
  • Extended uniquac

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