Method and arrangement for capturing CO
A system for capturing CO 2 from gases, a pre-cooled stream of the gases is conducted through a bed of CO 2 adsorbent in a first direction capturing CO 2 from the gases in the CO 2 adsorbent bed, a stream of warm heating gas is conducted from a heat storage unit to said CO 2 adsorbent bed in a second direction opposite the first direction transferring stored heat from the heat recovery unit to the adsorbent bed, while simultaneously transferring coldness from the adsorbent bed to the heat storage, the heating gas is conducted through the adsorbent bed in a closed loop desorbing CO 2 from the adsorbent bed, the desorbed CO 2 is extracted a stream of cooling gas is conducted through the heat storage unit and the CO 2 adsorbent bed in the first direction transferring low-temperature heat to the adsorbent bed and high-temperature heat from the adsorption bed to the heat storage unit.
1 . A method for capturing CO 2 from a CO 2 source including the steps of:
a) conducting a stream of CO 2 -containing gas through a bed of CO 2 adsorbent material capturing CO 2 from the streamed CO 2 -containing gas in the CO 2 adsorbent bed,
b) conducting a stream of heating gas through a heat storage and recovery unit comprising one or more beds of a storage material and said CO 2 adsorbent bed using a gas circulation pump, thereby transferring stored heat from said heat storage and recovery unit to said CO 2 adsorbent bed,
c) circulating said heating gas by means of a fan the gas circulation pump in a closed loop from the CO 2 adsorbent bed through a trim heater and back through the CO 2 adsorbent bed, thereby desorbing CO 2 from the CO 2 adsorbent bed into the heating gas, and extracting heating gas comprising desorbed CO 2 from the closed loop,
d) conducting a stream of cooling gas through the heat storage and recovery unit and the CO 2 adsorbent bed transferring heat from the CO 2 adsorbent bed to the heat storage and recovery unit.
2 . The method according to claim 1 , wherein in step a) the stream of CO 2 -containing gas is conducted through the bed of CO 2 adsorbent material in a first direction, in step b) the stream of heating gas is conducted through the heat storage and recovery unit and said CO 2 adsorbent bed in a second direction opposite said first direction, and in step d) the stream of cooling gas is conducted through the heat storage and recovery unit and the CO 2 adsorbent bed in the first direction.
3 . The method according to claim 1 , wherein the stream of CO 2 -containing gas is dried and cooled before being conducted to the CO 2 adsorbent bed.
4 . The method according to claim 3 , wherein the CO 2 -containing gas is dried by being conducted through a first desiccant wheel and then cooled by being conducted through a heat exchanger before being conducted to the CO 2 adsorbent bed, and wherein CO 2 -depleted gas, output from the CO 2 adsorbent bed, is returned through the heat exchanger and first desiccant wheel.
5 . The method according to claim 3 , wherein the CO 2 -containing gas is dried by being conducted through a first desiccant wheel and then through second desiccant wheel and then being cooled by being conducted through a heat exchanger before being conducted to the CO 2 adsorbent bed, and wherein CO 2 -depleted gas, output from the CO 2 adsorbent bed, is returned through the heat exchanger, first desiccant wheel and second desiccant wheel.
6 . An arrangement for capturing CO 2 from a CO 2 source according to the method claimed in claim 1 , the arrangement including:
a CO 2 capture container with the CO 2 adsorbent bed adapted to adsorb CO 2 during the adsorption step a. and desorb CO 2 during the desorption step c.,
wherein the arrangement further includes the heat storage and recovery unit comprising the one or more beds of the storage material adapted to transfer stored heat to the CO 2 adsorbent bed prior to the desorption step and recover heat from the CO 2 adsorbent bed after the desorption step,
an inlet conduit connected to a first port of a first three-way valve, wherein an input line of the CO 2 capture container is connected to a second port of the first valve, an output line of said container is connected to a first port of a second three-way valve, a second port of said second three-way valve is connected to an outlet conduit, a third port of said first three-way valve is connected to a first port of a third three-way valve, a second port of the third three-way valve is connected to a first port of the heat storage and recovery unit, a second port of the heat storage and recovery unit is connected to a third port of the second three-way valve, a bypass conduit is connecting a third port of the third three-way valve to the second port of the heat storage and recovery unit, the arrangement further including the gas circulation pump installed either at the third port of the first three-way valve or at the third port of the second three-way valve, the trim heater installed at the third port of the second three-way valve, and a CO 2 outlet conduit with an outlet valve;
wherein the closed loop is formed at least in part by the third port of the first three-way valve, the gas circulation pump, the first port of the third three-way valve, the third port of the third three-way valve, the trim heater, the third port of the second three-way valve, the first port of the second three-way valve, the CO 2 capture container and the second port of the first three-way valve; and
wherein the CO 2 outlet conduit is connected to the closed loop.
7 . The arrangement according to claim 6 , wherein the CO 2 adsorbent bed includes zeolite material.
8 . The arrangement according to claim 6 , wherein the heat storage and recovery unit includes several beds of a heat storage medium.
9 . The arrangement according to claim 8 , wherein the heat storage medium contains beads of a metallic or ceramic heat storage material.
10 . The arrangement according to claim 6 , wherein a gas intake conduit is connected to a drying input of a first desiccant wheel, a drying output of which is connected to a first side input of a heat exchanger, a first side output of which is connected to said inlet conduit, the outlet conduit is connected to a second side input of the heat exchanger, a second side output of the heat exchanger is connected to a gas outlet line, and wherein a recovery input of said first desiccant wheel is connected to gas outlet lines.
11 . The arrangement according to claim 10 , wherein a second desiccant wheel is installed between the first desiccant wheel and the heat exchanger.
12 . The method according to claim 1 , wherein the CO 2 -containing gas is air or a flue gas.
13 . The arrangement according to claim 9 , wherein the beads have a diameter in the range 3-10 mm.