Branholt / Columns

C-4

The reference column, one cycle, in the order it happens. This is the run the front page is printed from.

production · in service 2025-11 · 4,180 cycles · measured heel 0.061 mmol/g
ten stations, weight 100.0 to 860.2, spread 760.2
4.06 kg CO2 recovered a cycle, at 1.126 mmol/g working capacity

Fresh bed

t 0 min
q 0.000 mmol/g
weight 100.0
air off

A column just changed out. Nothing on the bed and nothing to give. Every number on this site starts from here.

The BR-4 pore field with 0.0 per cent of its drawn pore area inked, which is a loading of 0.000 mmol of CO2 per gram.
0.0% of pore area inked, at 640 weight units to the mmol/g

Air on

t 10 min
q 0.276 mmol/g
weight 277.0
adsorption

The fan starts: 4,200 cubic metres an hour of ordinary outdoor air, 420 parts per million of it the thing we are here for.

The BR-4 pore field with 22.1 per cent of its drawn pore area inked, which is a loading of 0.276 mmol of CO2 per gram.
22.1% of pore area inked, at 640 weight units to the mmol/g

Adsorbing

t 25 min
q 0.581 mmol/g
weight 471.8
adsorption

The bed takes CO2 fastest when it is emptiest. About half the working capacity arrives in the first twenty-five minutes.

The BR-4 pore field with 46.5 per cent of its drawn pore area inked, which is a loading of 0.581 mmol of CO2 per gram.
46.5% of pore area inked, at 640 weight units to the mmol/g

Filling

t 45 min
q 0.844 mmol/g
weight 640.3
adsorption

Three quarters of the way. From here each further gram costs more air than the one before it, because the sites left are the ones the gas has to find.

The BR-4 pore field with 67.5 per cent of its drawn pore area inked, which is a loading of 0.844 mmol of CO2 per gram.
67.5% of pore area inked, at 640 weight units to the mmol/g

Slowing

t 75 min
q 1.058 mmol/g
weight 777.3
adsorption

Ninety per cent of what this bed will hold is already on it. The last tenth takes another forty-five minutes.

The BR-4 pore field with 84.7 per cent of its drawn pore area inked, which is a loading of 1.058 mmol of CO2 per gram.
84.7% of pore area inked, at 640 weight units to the mmol/g

Breakthrough

t 120 min
q 1.188 mmol/g
weight 860.2
air off

The outlet analyser reads the inlet. The bed has stopped taking, so we stop giving it air. Running past this point buys nothing and costs fan power.

The BR-4 pore field with 95.0 per cent of its drawn pore area inked, which is a loading of 1.188 mmol of CO2 per gram.
95.0% of pore area inked, at 640 weight units to the mmol/g

Heat on

t 132 min
q 0.475 mmol/g
weight 403.9
desorption

95 °C and 80 millibar. The bond that held the CO2 at ambient does not hold at temperature, and the gas comes off into the collection line.

The BR-4 pore field with 38.0 per cent of its drawn pore area inked, which is a loading of 0.475 mmol of CO2 per gram.
38.0% of pore area inked, at 640 weight units to the mmol/g

Releasing

t 150 min
q 0.153 mmol/g
weight 197.6
desorption

Most of the batch leaves in these eighteen minutes. It is metered here, wet, before drying and compression.

The BR-4 pore field with 12.2 per cent of its drawn pore area inked, which is a loading of 0.153 mmol of CO2 per gram.
12.2% of pore area inked, at 640 weight units to the mmol/g

Nearly empty

t 165 min
q 0.087 mmol/g
weight 155.4
desorption

The last of it comes off slowly and at the worst energy cost in the cycle. Where a plant stops stripping is a commercial decision, not a chemical one.

The BR-4 pore field with 6.9 per cent of its drawn pore area inked, which is a loading of 0.087 mmol of CO2 per gram.
6.9% of pore area inked, at 640 weight units to the mmol/g

The heel

t 195 min
q 0.062 mmol/g
weight 139.8
vacuum closed

We stop at 0.06. That is the heel, the CO2 this bed does not give back at this duty, and the reason the last heading on this page is heavier than the first.

The BR-4 pore field with 5.0 per cent of its drawn pore area inked, which is a loading of 0.062 mmol of CO2 per gram.
5.0% of pore area inked, at 640 weight units to the mmol/g

Read it against the others

Reserve a tonne