Apparatus and methods for reducing carbon dioxide content of an air stream

• US 6,200,543 B1
• Filed: 02/25/1998
• Issued: 03/13/2001
• Est. Priority Date: 02/25/1998
• Status: Expired due to Term

• Current Assignee: Missippi Lime Company
• Original Assignee: Mississippi Lime Company
• Inventors: Lutman, Gary F., Allebach, William S., Griffard, Randy J., DeGenova, Mark G.
• Primary Examiner(s): Griffin, Steven P.
• Assistant Examiner(s): Vanoy, Timothy C.
• Application Number:
  US09/031,320
• Time in Patent Office: 1,112 Days
• Field of Search: 423/220, 423/230, 952/73, 952/85
• US Class Current: 423/220
• CPC Class Codes: B01D 2251/404 of calcium
• CPC Class Codes: B01D 2251/604 Hydroxides
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

Apparatus and methods for reducing CO₂ content of an air stream are described. A method of reducing CO₂ content of an air stream in accordance with one embodiment of the present invention includes the steps of first injecting hydrated lime into an air stream containing CO₂. The hydrated lime reacts with the CO₂ in the air stream to form calcium carbonate, CaCO₃. The air stream is then directed into a lime storage container having a dust collector. As air is drawn through the dust collector, hydrated lime and CaCO₃ are collected on the filter bags. The air drawn through the dust collector has a reduced CO₂ content as compared to the air prior to being injected with hydrated lime. The reduced CO₂ content air stream exhausted from the dust collector can then be directed to the different parts of the hydrated lime manufacturing process, such as the milling process, conveying and storing the hydrated lime.

Claims

1. A method of reducing CO₂ content of an air stream, said method comprising the steps of:

(a) injecting hydrated lime into an air stream containing CO₂ so that the hydrated lime reacts with the CO₂ in the air stream to form CaCO₃;

(b) directing the air stream, the injected hydrated lime, and formed CaCO₃ through an inlet conduit and into a lime storage container having a dust collector;

(c) collecting hydrated lime and CaCO₃ on the dust collector; and

(d) exhausting air from the dust collector.

2. A method in accordance with claim 1 further comprising the step of at least partially purging the dust collector of collected hydrated lime and CaCO₃ and allowing the hydrated lime and CaCO₃ to fall into the storage container, and wherein injecting hydrated lime into an air stream containing CO₂ comprises the step of injecting hydrated lime from the storage container into the CO₂ containing air stream.

3. A method in accordance with claim 2 wherein the dust collector comprises a plurality of filter bags, each bag having an outer surface.

4. A method in accordance with claim 3 further comprising the step of measuring a pressure drop across the filter bag surface in the dust collector and when the measured pressure drop exceeds a predetermined value, performing the step of at least partially purging the filter bags of collected hydrated lime and CaCO₃.

5. A method in accordance with claim 2 further comprising the step of measuring the CO₂ content of the air stream exhausted from the dust collector and when the measured CO₂ content is above a predetermined value removing the CaCO₃ and any hydrated lime from the storage container and then refilling the storage container to a predetermined level with virgin hydrated lime.

6. A method of reducing CO₂ content of an air stream, said method comprising the steps of:

filling a lime storage container having a dust collector with hydrated lime to a predetermined level;

injecting hydrated lime metered from the storage container into an air stream containing CO₂ so that the hydrated lime reacts with CO₂ in the air stream forming CaCO₃ and reducing the CO₂ content of the air stream, the air stream located outside of the lime storage container;

directing the air stream, injected hydrated lime, and formed CaCO₃ through an inlet conduit and into the lime storage container;

collecting hydrated lime and CaCO₃ in the dust collector; and

exhausting air with reduced CO₂ content from the dust collector.

7. A method in accordance with claim 6 further comprising the step of at least partially purging the dust collector of collected hydrated lime and CaCO₃ and allowing the hydrated lime and CaCO₃ to fall into the storage container, and wherein injecting hydrated lime into an air stream containing CO₂ comprises the step of injecting the collected hydrated lime in the storage container into the CO₂ containing air stream.

8. A method in accordance with claim 7 wherein the dust collector comprises a plurality of filter bags, each bag having an outer surface.

9. A method in accordance with claim 8 further comprising the step of measuring a pressure drop across the filter bag surface in the dust collector and when the measured pressure drop exceeds a predetermined value, performing the step of at least partially purging the filter bags of collected hydrated lime and CaCO₃.

10. A method in accordance with claim 7 further comprising the step of measuring the CO₂ content of the air stream exhausted from the dust collector and when the measured CO₂ content is above a predetermined value removing the CaCO₃ and any hydrated lime from the storage container and then refilling the storage container to a predetermined level with virgin hydrated lime.