METHOD TO SEPARATE A GAS MIXTURE CONTAINING CARBON DIOXIDE USING TWO STAGE ADSORPTION PROCESS

Abstract

The present invention provides for a method utilizing two sets of adsorber beds wherein one operates as a pressure swing adsorption system and the other operates as a vacuum swing adsorption system to separate carbon dioxide from a mixture of gases obtaining a higher purity of carbon dioxide thus separated than any prior art process.

Claims

1. An apparatus for separating carbon dioxide comprising: two sets of two adsorber beds (A1 & A2, B1 & B2 respectively), along with a buffer vessel (D1), vacuum pump (VP1), compressor (C1), product valves (2,4,9,11), feed valves (1,3,8,10), vent valves (5,7,12,14,15,17), equalization valves (6, 13), and check valve (16) as shown in FIG. 1, which allows separation of carbon dioxide gas from a mixture of gases such as flue gas to a concentration as high as 99% purity.

2. The apparatus of claim 1 comprising of two or more layers of adsorbent material in each of the adsorber beds.

3. The apparatus of claim 1 where set 2 of the process is regenerated under a vacuum level between −5 psig to −11 psig.

4. The apparatus of claim 1 where set 1 of the process receives feed gas between 3 psig and 15 psig.

5. The apparatus of claim 1 where set 1 of the process is regenerated under a pressure level between −1 psig to +2 psig.

6. The apparatus of claim 1 with a process cooler (HE1) to cool the feed gas at the compressor (C1) discharge.

7. The apparatus of claim 1 in which the feed gas is supplied under pressure or is compressed by compressor C1 to the desired pressure for set 1 of the process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is the process variation.

DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention provides for a process of separating carbon dioxide from a gas mixture on large scale through a series of two sets of multiple adsorption beds wherein the gas mixture go through set 1 for partial separation of carbon dioxide and the resultant mixture passes through set 2 to further purify the product gas.

[0011] The present inventors anticipate a series of two sets of multiple adsorption beds as shown in FIG. 1. Set 1 comprises of a two bed system with adsorber beds A1 and A2. The process feed gas is compressed by compressor C1 before going to bed A1 through valve 1 or A2 through valve 3. The product gas is withdrawn from A1 using valve 2 or A2 using valve 4. The vent waste gas is withdrawn from A1 through valve 5 and from A2 through valve 7. Valve 6 allows for equalization of bed A1 and bed A2 during switchover from regeneration to production and vice versa. The product gas with higher concentration of carbon dioxide from valve 2 or valve 4 are sent to a buffer tank D1. Set 2 compromises of a two bed system with adsorber beds B1 and B2. The process feed gas from D1 is sent through valve 8 or valve 10 to beds B1 and B2. The product gas is withdrawn from B1 and B2 using valve 9 or valve 11. The vent waste gas is withdrawn from B1 through valve 12 and from B2 though valve 14. Valve 13 allows for equalization of bed B1 and bed B2 during switchover from regeneration to production and visa versa. The product gas with the required concentration of carbon dioxide is sent to VP1, vacuum pump. The vent waste gas with higher concentrations of carbon dioxide will be recycled through valve 15 to set 1 of the process, while at lower concentration will be vented through valve 17 and check valve 16 as waste.