Amines/blends chemical absorption

DESCRIPTION

This infosheet contains information on chemical absorption technology employing all the amines other than the MEA solvent (see dedicated infosheet on MEA-based technologies). The other amines include secondary and tertiary amines, their blends, and mixtures including different additives. More information on various amines is given in this review paper.¹ The information provided here is for the amine-based solvents, which are publicly available or from the main technology providers. The process is similar to that of MEA-based technology as shown in the Figure below. The flue gas is sent to the absorber column, where it flows upward and comes into contact with the down-flowing aqueous amine solution. The CO₂ in the feed gas reacts with the amine to form a CO₂-rich solution. This solution is then heated in a regeneration column to release a pure CO₂ stream and regenerate the amine for reuse. For amine-based technology, there are various influencing factors towards specific energy consumption, namely CO₂ partial pressure with respect to the type of applications, type of amine used, specific heat integration concept, etc.

TECHNICAL ASPECTS (all % are volume-based)

Point sources: Power generation, cement/lime production, petrochemical & refineries, iron and steel, hydrogen generation, waste to power facilities.²

CO₂ concentration range: 2-30%² (typical), 0.1-70% (OASE)²

CO₂ capture efficiency: >99%²

CO₂ purity: >95%³

Min. feed gas pressure: 1.0 bar⁴

Max. feed gas temperature: 60 °C⁵

Typical scale:

Large (1 MtCO₂/yr for ADIP Ultra by Shell)²

Medium to large (75 ktCO₂/yr – 6 MtCO₂/yr for CANSOLV by Shell)²

Small to large (3 ktCO₂/yr – 3 MtCO₂/yr for OASE^® Blue by BASF)²

*Calculated based on 300 operational days per year.

Primary energy source: Thermal (steam)

Impurity tolerance: NOx = 20 ppm, SOx = 10 ppm, O₂ = minimum possible or use of O₂ inhibitors.⁶ (assumed same as for MEA)

Cansolv: SO₂ - 15-60 ppmv⁷; PM - <20 mg/Nm³; prescrubber removes 90% of SO₂ and NO₂⁸; Remaining SO₂ in feed gas is converted to sulfite in CO₂ absorber.⁷

FUNCTION IN CCU VALUE CHAIN

• Capture CO₂ from flue gases.
• Some solvents may be highly affected by flue gas impurities, requiring several pre-treatment steps depending on the impurity.
• Cansolv also removes other gases, such as SO₂, if present in small quantities.⁷

LIMITATIONS

• Tertiary amines have slower reaction kinetics compared to primary and secondary amine processes, often requiring larger absorption columns.
• Although tertiary amines require less energy for regeneration than primary or secondary amines due to their lower heat of absorption, the overall energy consumption is still significant.
• Aqueous amines can corrode equipment, especially with flue gas impurities like SOx, NOx, and O₂.

ENERGY

• Thermal (steam) is used for the regeneration of the solvent.
• Electricity is used for operating pumps, blowers, and control systems.

CONSUMABLES

• The solvent is used as a medium to capture CO₂. Some solvents may be lost and need make-up.
• Water is used in the process as a solvent diluent for the amine solution.

Energy and Consumables

Parameter	Value
Heat (GJ/tCO2)	OASE® Blue – 2.59-2.710 ACC™ S21 & S2611 – 3.4 MDEA (10%) + PZ (30%)12 – 1.9 Cansolv DC-1038 – 2.92 Cansolv DC-2018 – 2.33 Piperazine – 2.99 – 3.04 – 2.72 – 2.8513 MHI KS-1™ - 2.153,14
Electricity (kWh/tCO2)	OASE® Blue – 13510 MDEA (10%) + PZ (30%)12 – 224 Cansolv15 – 107.6 (69% compression) Piperazine – 107 – 81 – 74 – 7113 MHI KS-1™  – 1863,14
Solvent makeup (kg/tCO2)	Cansolv DC-1037 – <10%/yr ACC™ S2111 – 0.5-0.6 ACC™ S2611 – 0.2-0.3 MDEA (10%) + PZ (30%)12 – 0.92
Cooling water (t/tCO2)	OASE® Blue – 1.6310 (makeup) Cansolv DC-1038 – 44.4 Cansolv DC-2018 – 32.3 MHI KS-1™ - 2.63,14 (makeup) MDEA (10%) + PZ (30%)12 – 5.3 (makeup)
10 OASE blue technology; CO2 conc. 21.3%; CO2 purity >99.9%; capture capacity – 1.4 MtCO2/yr; capture efficiency - 95%; electricity includes CO2 compression to 158.5 bar. 11 Aker solutions ACC™ advanced solvents S21 and S26 solvents; CO2 conc. 3.4% and 4%, respectively; without heat integration; 87% capture. 12 CO2 conc. – 20.4%; CO2 capacity – 2227.5 tCO2/day; electricity includes compression to 110 bar. 8 Shell Cansolv; CO2 capacity – 132 tCO2/hr; uses mechanical vapor recompression 13 Piperazine solvent; increasing CO2 concentration 4% - 12% - 20% - 33%; electricity includes CO2 liquefaction at 20 bar and -20 °C. 3,14 Coal power plant; CO2 conc. – 12.3%; 90% capture efficiency; MHI KM-CR Process® with KS-1™ solvent; Heat is calculated from steam consumption (5.9 bar and 160 °C); electricity includes compression power, about 33.3%.

COSTS

CAPEX:

OASE^® Blue:  21.5 €/tCO₂¹⁰

Cansolv: 32.5 €/tCO₂¹⁶

MDEA (10%) + PZ (30%): 10.1  €/tCO₂¹²

Piperazine: 13.5 – 7.6 – 6.6 – 5.6 €/tCO₂¹³

MHI KS-1: 25.2 €/tCO₂^3,14

Main CAPEX: absorption column, stripping column, and main heat exchanger.

OPEX:

OASE^® Blue:  33.4 €/tCO₂¹⁰

Cansolv: 17.4 €/tCO₂¹⁶

MDEA (10%) + PZ (30%): 38.7  €/tCO₂¹²

Piperazine: 16 – 13.7 – 11.8 – 12 €/tCO₂¹³

MHI KS-1: 17.9 €/tCO₂^3,14

Main OPEX: steam, electricity, cooling water, and amine make-up.

CO₂ capture cost:

OASE^® Blue:  ~55 €/tCO₂¹⁰

Cansolv: ~50 €/tCO₂¹⁶

MDEA (10%) + PZ (30%): 48.7  €/tCO₂¹²

Piperazine: 29.5 – 21.3 – 18.4 – 17.6 €/tCO₂¹³

MHI KS-1: 43 €/tCO₂^3,14

CO₂ avoidance cost:

Cansolv¹⁶: 64.4 €/tCO₂

Piperazine¹³: 85 – 69 – 63 – 60 €/tCO₂ (estimated)

¹⁰ OASE blue technology; Steam-methane reforming plant; CO₂ conc. 21.3%; CO₂ purity >99.9%; capture capacity – 1.4 MtCO₂/yr; capture efficiency - 95%; electricity includes CO₂ compression to 158.5 bar; electricity price – 65 €/MWh; lifetime – 30 yrs.

¹⁶ Cansolv solvent; Coal power plant; CO₂ conc. – 13.3%; 90% capture efficiency; lifetime – 30 yrs; 3.58 MtCO₂/yr; 2015 euros; discount rate – 12%; operating hours – 7446 hr/yr; includes compression up to 110 bar; excludes transportation costs.

¹² MDEA (10%) + PZ (30%) solvent mixture; CO₂ conc. – 20.4%; CO₂ capacity – 2227.5 tCO₂/d; capture efficiency – 90%; CO₂ purity – 98%; includes CO₂ compression to 110 bar; electricity price – 58.1 €/MWh; steam price – 22.5 €/t; 90% capture efficiency; 2019 euros; plant lifetime – 25 yrs; interest rate – 15%; CRF – 0.154.

¹³ Piperazine solvent; values for CO₂ conc. – 4%, 12%, 20%, and 33%; CO₂ capacity – 0.168, 0.446, 0.709, 1.12 tCO₂/yr; piperazine concentration – ~8 mol-PZ/kgH₂O; excluding CO₂ liquefaction (20 bar and -20°C); including flue gas pretreatment; operating hours – 8000 hr/yr; electricity price – 64 €/MWh; steam price – 5.5 €/t; 90% capture efficiency; 2020  euros; plant lifetime – 20 yrs; interest rate – 6%.

¹⁴ MHI KM-CR Process^® with KS-1™ solvent; coal power plant; CO₂ conc. – 12.3%; 90% capture efficiency; CO₂ purity – >95%; 2.99 MtCO₂/yr; 2017 euros; CRF – 0.1243; operating hours – 6745 hr/yr; includes compression up to 152.7 bar and 35 °C; process steam at 5.9 bar and 160 °C; excludes transportation costs.

ENVIRONMENTAL

CO₂ footprint: Not available. Can be considered same as the MEA-based chemical absorption technology (see infosheet).

Spatial footprint:

Amine scrubbing: 37,500 m² (250x150) for 2.56 MtCO₂/yr, which also includes compression system¹⁷ (assuming it to be the same as MEA-based process).

Cansolv DC-103 solvent: 465 m² for 100 tCO₂/day ⁷

MHI KS-1™ solvent: 19,166 m² (550x370) for 2.99 MtCO₂/yr  (including capture island, compression system, cooling tower, and wastewater treatment)¹⁴

Environmental issues: solvent emissions, heat stable salts waste, water usage, and wastewater management.

ENGINEERING

Maturity: Commercial (TRL 9)²

Large-scale commercial plants are operational for various solvents.

Retrofittability: Moderate

It can be integrated into existing industrial facilities without substantial modifications to the main process. The heat and electricity sources, and waste removal are required.

Scalability: High

Suitable for both medium and large-scale CO₂ capture operations (modular system).²

Process type: Liquid solvent based with chemical reactions.

Deployment model: Centralized or Decentralized.

Decentralized CO₂ absorption at point sources with centralized desorption.

Technology flexibility: Hybridization with other capture technologies is feasible. Other technologies can be used to increase CO2 concentration.

TECHNOLOGY PROVIDERS

• CANSOLV by Shell, United Kingdom
• ADIP Ultra by Shell, United Kingdom (MDEA as the main reactant and piperazine as the accelerator)
• OASE® Blue by BASF, Germany
• ASCC by Honeywell, United States
• SUSTENOL™ by Susteon, United States (mixed-amine solvent, regeneration energy = 2.01 GJ/t CO₂, capture efficiency = 96.2%, capture cost = €45/t CO₂)
• ION solvent by ION Clean Energy, United States (99% capture efficiency; greater stability; low emissions; faster kinetics; low energy requirements)
• CycloneCC™ by Carbon Clean, United Kingdom (uses rotating packed beds and amine-based proprietary APBS-CDRMax solvent; lowers energy demand by 10-25%, reduces corrosion by a factor of 20, decreases degradation by a factor of 10, and has a lifespan that is five times longer than conventional solvents)
• KM CDR Process® by Mitsubishi, Japan
• Just CatchTM and Big CatchTM by SLB Capturi, Norway (formerly Aker Carbon Capture)
• Lummus CO₂ recovery by Lummus Technology, United States (up to 97% CO₂ recovery)

INNOVATIONS

• Piperazine-activated amine blends: Blending tertiary amines like methyl diethanolamine (MDEA) with piperazine (PZ) has been found to enhance CO₂ absorption rates and thermal stability.¹⁸
• Amine-based solvents and additives: Enhancing CO₂ capture efficiency, reducing energy requirements, minimizing solvent degradation, and mitigating equipment corrosion.¹⁹

CONTACT INFO

Mohammed Khan (mohammednazeer.khan@vito.be)

Miet Van Dael (miet.vandael@vito.be)

ACKNOWLEDGEMENT

This infosheet was prepared as part of the MAP-IT CCU project funded by VLAIO (grant no. HBC.2023.0544).

REFERENCES

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