I am looking for a circuit that will charge 8.1 volt capacitor (3 2.7v 400f in series) using a 24VDC power supply. I want to limit the charging current to no more than 100ma.
KAM appears to be a Korean supplier of superCaps and yes it is 400 Farads. These are used for backup so they have a fairly high ESR.
If they are not matched identically upon charging, the voltage will not be equal, so parallel clamps, other zener like parts are needed to prevent over voltage.
When it is drained in series, there is a risk a lower value of capacitance can be discharged quicker and then be reverse biased. This will accelerate aging effects of high ESR. Reverse diode protection will extend the life.
This might seem overkill, but if you don't the risk of failure is catastrophic.
You are best to consult with KAM on the schematic for specs on series charging. I count 14 parts per Cap including transistors.
If you want to design your own, here are a couple ideas; Using the TL431 precision voltage reference as a programmable zener, you can use it to limit the voltage and current instead of a 240 ohm series resistor. ( simple 100mA start current limiter)
This is my simple Cap triad limiter simulation with Cap ESR of 1ohm (which is SWAG at best)
Replace Zener and current source with TL431 app note schematics. It is a <1% 100mA 2.5V ref so you need 2R's to make 2.7V to program the voltage from 2.5 to 2.6 with R ratios. The TL431 also has a reverse diode to protect the cap but the overall circuit does not (yet) have current limit protection for reverse voltage.