In CO2 removal plants, regenerators are used to remove CO2 from a gas stream by absorbing it into a liquid solvent. Overhead systems in regenerators are used to separate and recover the CO2-rich solvent from the gas stream, and to recycle the solvent back to the absorber for further CO2 removal.


Carbon dioxide (CO2) removal plants are used to capture and remove CO2 from a gas stream in order to reduce greenhouse gas emissions and mitigate the impacts of climate change. There are several technologies and methods that can be used to remove CO2 from a gas stream, including absorption, adsorption, and membrane separation.

One of the most commonly used technologies for CO2 removal is absorption, which involves the use of a liquid solvent to absorb CO2 from a gas stream. Absorption systems typically consist of an absorber and a regenerator, which work together to remove and recover the CO2 from the gas stream.

In the absorber, the gas stream is contacted with the liquid solvent, which absorbs the CO2 and becomes saturated with it. The CO2-rich solvent is then sent to the regenerator, where the CO2 is separated and recovered. The CO2-depleted solvent is then returned to the absorber to be used again.

Overhead systems in regenerators are used to separate and recover the CO2-rich solvent from the gas stream, and to recycle the solvent back to the absorber for further CO2 removal. There are several types of overhead systems that can be used in regenerators, including condenser systems, flash drum systems, and distillation systems.

  1. Condenser systems: use a heat exchanger to condense the solvent and separate it from the CO2-depleted gas stream. The condensed solvent is then collected and returned to the absorber for reuse. Condenser systems are simple and reliable, and they require minimal maintenance. However, they can be less energy efficient compared to other types of overhead systems.
  2. Flash drum systems: use a drum or vessel with a pressure relief valve to separate the solvent from the CO2-depleted gas stream. As the gas stream enters the drum, the pressure is reduced, causing the solvent to flash or vaporize and separate from the gas stream. The vaporized solvent is then collected and returned to the absorber for reuse. Flash drum systems are simple and require minimal maintenance, but they can be less energy efficient compared to other types of overhead systems.
  3. Distillation systems: use a distillation column to separate the solvent from the CO2-depleted gas stream. The gas stream is passed through the column, and the solvent is collected and returned to the absorber for reuse. Distillation systems are more complex and require more maintenance compared to other types of overhead systems, but they are generally more energy efficient and can achieve higher levels of separation and recovery.

The type of overhead system used in a regenerator will depend on the specific requirements of the CO2 removal process and the characteristics of the solvent being used. Factors to consider include the purity of the CO2 product, the energy efficiency of the system, the reliability and maintenance requirements of the system, and the cost of the system.

In addition to the overhead system, regenerators also typically include a heat exchanger and a cooler, which are used to transfer heat between the solvent and the gas stream. The heat exchanger is used to heat the solvent as it enters the regenerator, which helps to drive the separation and recovery of the CO2. The cooler is used to cool the solvent as it leaves the regenerator, which helps to condense the solvent and prevent vaporization.

Overall, overhead systems in regenerators play a crucial role in the CO2 removal process by separating and recovering the CO2-rich solvent and recycling it back to process.