Heat integration of a cement manufacturing plant with an absorption based carbon dioxide capture process
View Patent ↗The present invention relates to methods and systems for improving the utilization of energy in a cement manufacturing plant comprising an absorption based contaminant, e.g. CO 2 , capture process using thermal regeneration of a liquid absorbent. The methods and systems of the present invention are characterized in that the thermal regeneration of the liquid absorbent is at least partially effected using a hot exhaust gas stream generated in the kiln of the cement manufacturing plant.
1. A method of cleaning an exhaust gas stream generated in a cement kiln, the method comprising:
a) scrubbing in a scrubbing step a contaminant rich exhaust gas stream with a liquid absorbent such that a contaminant rich liquid absorbent is formed;
b) cleaning the contaminant rich liquid absorbent by heating it to separate contaminant from the liquid absorbent, such that a contaminant lean liquid absorbent is regenerated; and
c) recycling regenerated contaminant lean liquid absorbent for use in the scrubbing step;
characterized in that the heating of rich liquid absorbent is at least partially effected using a hot exhaust gas stream generated in the cement kiln.
2. A method of cleaning an exhaust gas stream generated in a cement kiln, the method comprising:
a) scrubbing in a scrubbing step a CO 2 rich exhaust gas stream with a liquid absorbent such that a CO 2 rich liquid absorbent is formed;
b) cleaning the CO 2 rich liquid absorbent by heating it to separate CO 2 from the liquid absorbent, such that a CO 2 lean liquid absorbent is regenerated; and
c) recycling regenerated CO 2 lean liquid absorbent for use in the scrubbing step;
characterized in that the heating of CO 2 rich liquid absorbent is at least partially effected using a hot exhaust gas stream generated in the cement kiln.
3. A method of cleaning an exhaust gas stream generated in a cement kiln, the method comprising:
a) scrubbing in a scrubbing step an NH 3 rich exhaust gas stream with a liquid absorbent such that an NH 3 rich liquid absorbent is formed;
b) cleaning the NH 3 rich liquid absorbent by heating it to separate NH 3 from the liquid absorbent, such that an NH 3 lean liquid absorbent is regenerated; and
c) recycling regenerated NH 3 lean liquid absorbent for use in the scrubbing step;
characterized in that the heating of the NH 3 rich liquid absorbent is at least partially effected using a hot exhaust gas stream generated in the cement kiln.
4. A method according to claim 1 , wherein said hot exhaust gas stream comprises exhaust gas directly from the cement kiln.
5. A method according to claim 1 , wherein said hot exhaust gas stream comprises exhaust gas from the cement kiln first used in pre-heating of the cement raw materials and/or subjected to dust removal.
6. A method according to claim 1 , wherein said hot exhaust gas stream is formed by blending exhaust gas directly from the cement kiln with exhaust gas from the cement kiln first used in pre-heating of the cement raw materials and/or subjected to dust removal.
7. A method according to claim 1 , wherein said hot exhaust gas stream is used for heating of the liquid absorbent by indirect heat exchange.
8. A method according to claim 1 , wherein said hot exhaust gas stream is used to produce steam, and said steam is used for heating the liquid absorbent by indirect heat exchange.
9. A method according to claim 2 , wherein said hot exhaust gas stream used for heating the liquid absorbent is subsequently directed to the scrubbing step.
10. A method according to claim 2 , wherein said liquid absorbent is an aqueous amine or ammonia solution or slurry.