The Tomakomai CCS Demonstration Project was launched in FY2012 by the Ministry of Economy, Trade and Industry (METI), aiming for the practical use of CCS in Japan around 2020. Between FY2012 to FY2017, the project was commissioned to Japan CCS Co, Ltd (JCCS) by METI, and from FY2018, the project has been commissioned by the New Energy and Industrial Technology Development Organization (NEDO). CO2 injection was started on April 6, 2016, and on November 22, 2019, the target of 300,000 tonnes of cumulative injection was achieved. The injection has been terminated, whereas monitoring operations are being continued.
The features of the project are summarized below.
• The CO2 containing gas is extracted from a Hydrogen Production Unit (HPU) of an existing petroleum refinery and delivered from downstream of PSA (Pressure Swing Adsorption) of HPU to the capture facilities located outside the refinery boundary via a 1,400m pipeline.
• The CO2 capture, compression and injection activities as well as monitoring of the injected CO2 can be controlled at one location, and the CO2 rate is 25.33 tonnes per hour.
• The PSA off-gas is treated by an activated alkanol amine solution to capture the CO2, which is compressed and injected into two offshore sub-seabed reservoirs by two separate deviated injection wells. The injection well for the shallow reservoir has a vertical depth of 1,188m and horizontal reach of 3,058m, whereas the well for the deep reservoir has a vertical depth of 2,753m and horizontal reach of 4,346m.
An objective of the project was to demonstrate the low heat energy consumption of the CO2 capture process, because the cost of heat energy consumption dominates the OPEX of a CCS project. JCCS conducted an evaluation of several existing processes as well as process configurations over two years, and consequently selected the OASE® process (licensed by BASF). The capture process is comprised of an Absorber, Stripper and Low-Pressure Flash Tower (LPFT). The Absorber has a dual function of bulk absorption (lower part) and lean absorption (upper part). This process is called “Two-stage absorption”, whereby the rich amine solution from the bottom of the Absorber is sent to the LPFT where 60-70 % of the absorbed CO2 is flashed without direct heating, achieving a significant reduction in heat energy of the amine reboiler. The Tomakomai Twostage absorption process achieved an average reboiler heat of 0.907GJ/t-CO2, which was approximately a 50-70 % reduction compared to one-stage absorption processes which require large amounts of heat ranging from 2 to 3 GJ/t-CO2. This result places the heat consumption for the Tomakomai CO2 capture process at the lowest level among operating CCS plants in the world. As a study to further reduce the amine reboiler heat, process simulation studies of an “innovative process layout” were executed. The overall flash effect could be increased by about 10% from the layout with LPFT alone, and the reboiler heat could be further reduced to 0.487 GJ/t-CO2.
Audience Take Away:
• Feasibility Study of Carbon dioxide Capture and Storage (CCS).
• Process selection for Pre-combustion CO2 Capture.
• Design of CO2 Capture Process using alkanol amine solution.
Energy saving of CO2 Capture Process using alkanol amine solution.