Harvesting CO2 reaction enthalpy from amine scrubbing

Amine-based CO2 capture technology suffers high energy consumption, of which the exergy loss of CO2 absorption enthalpy is a significant contributor to the process irreversibility. Recovery and utilisation of CO2 absorption enthalpy is therefore of paramount significance to advance amine technology towards low capture cost. The present study proposed a reaction enthalpy harvesting amine process (REHA) with the purpose to directly utilise the CO2 absorption enthalpy for building heating. In the REHA process, we redefine the operational conditions of CO2 capture process with dual targets of high capture performance as well as high enthalpy recovery. It is revealed that using the benchmark mono-ethanolamine (MEA) absorbent 1.62 GJ/tonne CO2 could be harvested though process modification and multiple heat extraction, enabling a high energy recovery efficiency of 82%, whilst maintaining 90% absorption efficiency and low heat requirement of 2.6 GJ/tonne CO2. Integration of REHA with CO2 capture process enables an appreciable cost of CO2 avoided decreased from $63.5/ tonne to $54/tonne CO2 (16% reduction) at a heat price of $7/GJ and 5-months heat supply. The economic viability of REHA process is anticipated to be further promoted with the rise of heating price and increasing demand of space heating.

Automated summary

This study proposes a new amine process that utilizes CO2 absorption enthalpy for building heating. By modifying the process and extracting heat, high efficiency CO2 capture and enthalpy recovery are achieved. This method significantly reduces CO2 avoidance cost and is economically viable with increasing demand for heating.