Gas capture system with combined temperature and pressure swings using moving adsorbent

1 . A gas capture system comprising:

a first reactor system arranged so that, in the first reactor system, at least some gas in a gas stream that is received by the gas capture system is captured by a sorbent that is arranged to flow through the first reactor system, wherein a sorbent inlet of the first reactor system is located above a sorbent outlet of the first reactor system such that the direction of sorbent flow through the first reactor system is vertically downwards;

a second reactor system arranged to regenerate the sorbent so that the sorbent releases at least some of the gas captured in the first reactor system, wherein the sorbent is arranged to flow through the second reactor system and the second reactor system is arranged to output a flow of the released gas, wherein a sorbent inlet of the second reactor system is located below a sorbent outlet of the second reactor system such that the direction of sorbent flow through the second reactor system is vertically upwards;

a first sorbent transfer system arranged between the sorbent outlet of the first reactor system and the sorbent inlet of the second reactor system, wherein the first sorbent transfer system comprises a lock hopper;

a second sorbent transfer system arranged between the sorbent outlet of the second reactor system and the sorbent inlet of the first reactor system, wherein the second sorbent transfer system comprises a lock hopper; and

a heat pump system arranged to transfer heat between the first reactor system and the second reactor system

wherein:

the sorbent is a solid;

the second reactor system comprises a pump configured to reduce the pressure in the second reactor system so that the second reactor system has a lower operational pressure when regenerating sorbent than the operational pressure of the first reactor system during gas capture by the sorbent, wherein the pump is arranged to extract gas through a gas extraction outlet of the second reactor system and the gas extraction outlet is located such that there is a gas flow vertically upwards from the sorbent inlet end of the second reactor system;

the first reactor system, first sorbent transfer system, second reactor system and second sorbent transfer system are all arranged so that they provide a sorbent flow path that recirculates the sorbent vertically downwards through the first reactor system, through the first sorbent transfer system, vertically upwards through the second reactor system, and through the second sorbent transfer system; and

the second reactor system is arranged to regenerate the sorbent by heating the sorbent with heat received from at least the heat pump system.

2 . The gas capture system according to claim 1 , wherein, in the first reactor system, the sorbent is in a substantial counter flow with the gas stream.

3 . The gas capture system according to claim 1 , wherein the first reactor system comprises a plurality of reactors configured to provide mass transfer between a gas stream and the sorbent;

the gas stream is arranged to flow through each reactor; and

the sorbent is arranged to flow through each reactor.

4 . The gas capture system according to claim 1 , wherein the first reactor system comprises a counter current fluidised bed reactor.

5 . The gas capture system according to claim 1 , wherein the lock hopper of the second sorbent transfer system comprises:

an upstream valve;

a chamber; and

a downstream valve;

wherein:

the upstream valve is arranged between the chamber and the sorbent outlet of the second reactor system;

the downstream valve is arranged between the chamber and the sorbent inlet of the first reactor system;

the lock hopper is operable so that when the upstream valve is open and the downstream valve is closed, sorbent is arranged to flow from the second reactor system into the chamber; and

when the upstream valve is closed and the downstream valve is open, sorbent is arranged to flow from the chamber to the first reactor system; and

wherein the lock hopper of the second sorbent transfer system further comprises a pump; and

the lock hopper is operable so that when the upstream valve is closed and the downstream valve is closed, the pump removes at least some of the gas from the chamber.

6 . The gas capture system according to claim 1 , wherein the first heat pump system is arranged to recirculate a working fluid between a reaction region in the first reactor system and a regeneration region in the second reactor system such that heat is transferred from the reaction region to the regeneration region;

wherein the heat pump system comprises a compressor arranged to compress the recirculated working fluid.

7 . The gas capture system according to claim 1 , wherein the operational temperature of the second reactor system when the sorbent is regenerated is higher than the operation temperature of the first reactor system when the gas is captured.

8 . The gas capture system according to claim 1 , wherein the first reactor system is configured to react sorbent with the gas stream at an operational temperature in a range of about 40° C. to 90° C.; and

wherein the second reactor system is configured to regenerate sorbent at an operational temperature in a range of about 60° C. to 130° C.

9 . The gas capture system according to claim 1 , wherein the operational pressure of the second reactor system is at least a partial vacuum.

10 . The gas capture system according to claim 1 , wherein:

the sorbent comprises one or more of polyethylenimine, a metal organic framework based sorbent, zeolite, activated carbon, 3D graphene, any substance for chemi-, phys-sorption and/or hydrids of these; and/or

the particle size of the sorbent is in the range 100 μm to 1000 μm.

11 . The gas capture system according to claim 1 , wherein the received gas stream by the gas capture system is a flue gas.

12 . The gas capture system according to claim 1 , wherein the received gas stream by the gas capture system is a gas mixture generated by a reforming process.

13 . The gas capture system according to claim 1 , wherein the gas captured by the sorbent is carbon dioxide.

14 . The gas capture system according to claim 1 , wherein the gas captured by the sorbent is one or more of hydrogen sulphide, SOx, hydrogen and NOx.

15 . The gas capture system according to claim 1 , wherein, in use, phase changes of the working fluid that is recirculated by the heat pump system occur in a reaction region in the first reactor system and/or in a regeneration region of the second reactor system; and

wherein, the phase changes of the working fluid occur at a substantially constant temperature.

16 . The gas capture system according to claim 1 , further comprising a steam inlet arranged to receive a flow of steam so that steam may be injected into the flow of sorbent that is received by the second reactor system; and

wherein, in use, heat in the first reactor system is used to generate steam that is injected into the flow of sorbent that is received by the second reactor system.

17 . The gas capture system according to claim 1 , further comprising a cooler arranged in the sorbent flow path between the lock hopper in the second sorbent transfer system and the first reactor system;

wherein the cooler is arranged to cool the sorbent in the sorbent flow path between the lock hopper in the second sorbent transfer system and the first reactor system.

18 . The gas capture system according to claim 1 , wherein the heat pump system is a first heat pump system and the gas capture system, further comprises a second heat pump system arranged to cool the gas output from the second reactor system; and

wherein the second heat pump system is arranged to provide heat for generating steam for injecting into the flow of sorbent that is received by the second reactor system.

19 . The gas capture system according to claim 1 , further comprising a control system for reconfiguring the operation of the gas capture system;

wherein:

the control system is arranged to vary the heat transfer from the first reactor system to the second reactor system; and/or

the control system is arranged to vary the pressure difference between the first reactor system and the second reactor system; and/or

the control system is arranged to vary the temperature difference between the first reactor system to the second reactor system; and/or

the control system is arranged to control the use of heat from the heat pump system for the generation of steam for injection into the flow of sorbent that is received by the second reactor system; and/or

the heat pump system is a first heat pump system and the gas capture system further comprises a second heat pump system, and the control system is arranged to control the use of heat from the second heat pump system for the generation of steam for injection into the flow of sorbent that is received by the second reactor system.