By Jeff Allison, President, Delta Cleantech
There are punitive penalties for companies emitting carbon dioxide in the form of a carbon tax that quantifies and monetizes carbon emissions costs. Due in part to this, interest in carbon capture is growing as companies and countries work to decarbonize their operations using a number existing and emerging options. Delta Cleantech’s CO2 Capture Technology works post combustion to capture CO2 from exhaust streams, which an operator can then use or sequester.
Post Combustion Carbon Capture overview:
One of the most cost effective and commercially proven methods to capture CO2 from a smokestack is the Post Combustion CO2 capture process. Absorption refers to the uptake of CO2 into the bulk phase of another material, such as dissolving CO2 molecules into a liquid solution, and does not include instances where CO2 adheres to the surface of another material (adsorption). Absorption is the most mature method of CO2 separation and is widely used in gas processing applications. The process typically occurs in an absorber tower where flue gases are injected at the base and contacted with the liquid solvent as the gasses rise through the column. The CO2 is separated from the gas stream due to the high solubility of CO2 in the solution relative to the other flue gas constituents. The CO2-rich solution is then sent to a regenerator where the CO2 is stripped (usually via heating), the solvent is recycled, and the CO2 is captured as shown in Figure 1.
Figure 1 Example absorption process Source: National Petroleum Council
Typical sorbents used in the process are monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP). The process is commonly called amine absorption by the industry due to the dominance of amines compared to other solvents. Amines are widely used today to separate acid gases such as CO2 and H2S from a variety of gas streams. The solvent is often a blend of one or more types of amines and additives in an aqueous solution that reacts chemically with CO2 in an acid-base reaction to form a salt. The salts are then converted back into the acid gas and the base (amine) using high temperatures and reduced partial pressures. From a sustainability perspective. Despite the maturity of amine capture, the carbon capture industry continues to improve the process and technology. Amine capture technologies must consider the absorption rate (equipment size), capture capacity (solvent volume, equipment size), desorption rate (equipment size), heat requirements (energy costs), and robustness (operating costs and emissions) among other considerations. Amines must offer fast absorption rates, where the solvent captures CO2 quickly during exposure. The capital cost of a carbon capture project is often driven by the size and capacity of the absorber tower needed to separate CO2 from the flue gas. The faster a solvent can absorb CO2, the smaller the equipment size for the same flue gas stream. Amines need to have high net CO2 carrying capacities, lowering the amount of solvent required for capture. The amount of energy required to heat the CO2-rich amine solution and separate the two components is a key consideration in amine selection. Lastly, the amine must be resistant to thermal and oxidative degradation over time and offer low volatility to ensure that capture capacity is optimized, and the number of side reactions are at a minimum. Based on these requirements, the industry continues to produce incrementally more efficient and resilient solvent blends compared to traditional amine chemistry that can achieve increasing absorption and decreasing reaction heat targets.
Figure 2: Traditional amine performance versus target
Overall, Amine capture offers a proven solution for point-source carbon capture that is the industry standard today. The process is particularly advantaged in situations where waste heat or cheap energy is available to fuel the regeneration process. Water availability is also a factor in many current designs due to the need to cool the flue gas and remove particulate emissions. Leading-edge designs are exploring ways to use ambient air to cool the flue gas in areas where freshwater is limited. Amine capture facilities are often constrained by the need for a tall absorber tower to facilitate high capture rates. Because no two emitters produce an identical flue gas, the industry is increasingly tailoring amine chemistry to fit individual emissions sources to optimize performance. To prevent solvent degradation and the formation of other compounds, operators also use amine purification units to ensure that the amine solution at the top tray of the absorber remains pure. Net-net, amine capture remains a proven, cost-effective point-source capture solution that can handle most emissions with CO2 concentrations above 3%.
A Canadian based post combustion CO2 capture provider working with Scovan
Delta CleanTech is a Canadian based leader specializing in post-combustion carbon capture using open-source custom designed amine solutions. The company has operations globally and offers a full suite of carbon capture solutions and related services. Delta’s primary businesses units are CO2 capture, solvent purification and recovery, and Carbon Credit validation, certification, and trading through the company’s Carbon Rx business. Delta’s carbon capture process tailors solutions to client needs to optimize technical, economic, and environmental performance. Delta formulates a solvent and allows the customer to order it through the existing supply chain, reducing costs.
Delta’s technology has been used in projects across the globe, including in Canada, the U.S., Europe, UAE, Australia, and China. One noteworthy example is in Canada where Delta’s technology was selected to capture CO2 for Canada’s XPRIZE CO2 utilization competition at the Shepard Energy Center natural gas-fired power plant in Calgary, Alberta. Delta’s carbon capture plant was the first in the world to be recognized as ISO validated for process design, highlighting Delta’s expertise and credibility.
Originally published in Scovan’s IGNITE Vol. 5