Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Carbon dioxide or hydrogen sulfide component
Patent
1994-12-23
1996-05-28
Straub, Gary P.
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Carbon dioxide or hydrogen sulfide component
423220, 423437M, 95139, B01D 5362, B01D 5396
Patent
active
055208940
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a process for removing carbon dioxide from hot gas streams.
BACKGROUND OF THE INVENTION
The production of carbon dioxide in energy generation processes is becoming more and more of a problem worldwide. The increased concentration of carbon dioxide in the atmosphere results in reduced heat radiation from the Earth, which causes the temperature on Earth to rise and a number of life-determining processes to be perturbed. A solution for this problem can be sought in limiting the consumption of energy and, in addition, in forms of energy generation which do not yield carbon dioxide, such as combustion of hydrogen, nuclear energy and solar energy. The effect of solutions of this type is limited, certainly in the short and medium term, so that it is, at most, a question of reduced increase of the production of carbon dioxide.
When fossil fuels are gasified, the main products are hydrogen and carbon monoxide, the most desirable component of the two being hydrogen. The shift from carbon monoxide to hydrogen can be effected, for example, by treatment with water (steam). This again produces carbon dioxide which causes the problems outlined above.
Methods for removing carbon dioxide from gas streams do exist, but they have the drawback that they result in a considerable decrease (approximately 10%) of the efficiency of the energy generation (see K. Blok and C. A. Hendriks, "Voorstellen voor de integrerende studie ter afsluiting van het SOP CO.sub.2 " [Proposals for the Integrating Study at the close of the Coherent Research Package CO.sub.2 ]. State University of Utrecht, December 1991; Techniques for Absorption or Fixing of CO.sub.2, Technieuws Tokyo, volume 29 (1), May 1991, publication of the Dutch Ministry of Economic Affairs.
Japanese Patent Application 51-4090 discloses a process for removing water and CO.sub.2 from hot gases, in particular in the manufacture of steel, by treating the gases with CaO and/or MgO. The used oxide can be regenerated, according to this process, by hot air being passed through. In U.S. Pat. No. 3,516,808 a process is described for regenerating calcium oxide which has been used for removing CO.sub.2. According to Dutch Patent Application 82.02061 (=GB-A-2,103,645), CO.sub.2 and H.sub.2 S can be removed in a wet process from gases such as hydrocarbons by treatment with a solution of a tertiary amine and a physical absorbent. Japanese Patent Application 61-146344 discloses a process wherein CO.sub.2 and water are removed from inert gases by utilising a zeolite bed which is regenerated by heating with combustion gases of a catalysed combustion of propane.
SUMMARY OF THE INVENTION
A process has now been found by means of which, using any of the current carbon-containing sources of energy such as bituminous coal, petroleum and natural gas, carbon dioxide can be removed, effectively and regeneratively, from the combustion gases or gasification gases, and can be compressed, and in which the decrease in the efficiency can be kept within acceptable limits (less than approximately 5%).
The process according to the invention is characterised in that the gas stream is successively: dioxide; is absorbed on the absorbent, and: and optionally under elevated pressure and is then returned to step c).
According to this process, the gas stream is stripped of carbon dioxide by the absorbent at a temperature at which the absorption heat liberated can be used in the energy-producing process. The loaded absorbent is then regenerated, with the aid of heat present in the energy-producing process, at an elevated temperature, possibly also at an elevated pressure, carbon dioxide dissociating off. The carbon dioxide liberated during the desorption can, if necessary, be compressed further, before it is utilised or discharged. In this process the energy generated in the energy-producing process is thus utilised for the separation, and optionally the compression, of the carbon dioxide. The efficiency of the energy-producing process does not, however, drop as a re
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Heesink Albertus B. M.
Temmink Herman M. G.
Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk On
Straub Gary P.
Vanoy Timothy C.
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