The Project objective was to demonstrate a heat integrated CO2 desorber for regeneration of solvent in an amine based process for CO2 capture. The purpose of the new desorber design was to reduce temperature in the top section of the desorber and hence minimize the water content in the CO2 stream exiting the desorber. This will in turn reduce the CO2 capture process heat demand. Based on process simulations and calculations on heat and mass transfer, a new desorber concept was developed.
A new desorber module was constructed and installed at Aker Solutions’ Mobile Test Unit (MTU). In MTU tests with the new desorber, the desorber showed efficient heat transfer between lean solvent and rich solvent. Compared to tests with a traditional desorber, 10 - 15% reduction in SRD was achieved with the heat integrated desorber. This saving is linked to the reduction in desorber overhead temperature, resulting in reduced steam content in the exiting CO2 stream.
The effect of the heat integrated desorber is similar to that obtained by Lean Vapor Recompression (LVR) with respect to savings in externally supply of heat, while the energy for vapor compression is saved.
Through the project it was learned that there is a limited room for low grade heat recovery; the desorption process cannot utilise all low grade heat available. Due to these fundamental limitations in low grade heat recovery potential, other desorber configurations will not perform any better for a given solvent and desorber pressure.