PTQ Q1 2024 Issue

Compressor stages (high-P)

Dehydration stages

Compressor stages (low-P)

Cooler

Regenerator

2 3

Dense phase (supercritical) CO

8 – 9

CO gas

2 3

Glycol contactor

Heat exchanger

CO transport, pipeline

Reboiler

Rich glycol

Lean glycol

Displaced HO

Dense phase (supercritical) CO

Reservoir

CO storage

Figure 2 Downstream compression, dehydration, and storage filtration and separation needs

Which capture technologies are favourable highly depends on process economics, often cited in units of $/ton CO₂. Because CO₂ does not have an intrinsic value, instal - lations are driven by credits and regulations. This drives the industry to seek the lowest expense-proven solution and actively pursue technologies that offer cost reduction and increased equipment lifetime. Solving the contaminant challenge In the critical-to-decarbonise industrial sectors, CO₂ is typically captured after a combustion process. Therefore, flue gas feed streams entering CO₂ capture processes can contain an elevated level of combustion byproduct con- taminants. These feed contaminants can increase process operating expenses by (1) increasing the need for water replacement in wash systems and direct contact coolers, (2) increasing the frequency of solvent, membrane, or adsor- bent replacement, (3) for solvent-based processes, causing amine emissions in the flue gas outlet from the absorber, and (4) fouling critical process equipment such as heat exchangers, reboilers, compressors, and absorber inter- nals, thereby reducing process efficiency, increasing energy requirements, and requiring more frequent maintenance.

Additionally, contaminants can be generated during the carbon capture process. For instance, corrosion byprod - ucts, solvent degradation compounds, and heat-stable salts can build up over time in solvent loops. Similarly, in downstream process steps, lube oil and solid con- taminants can be introduced into the concentrated CO₂ stream. These contaminants also increase operating expenses by contaminating successive stages of equip- ment, leading to off-specification pipeline contents, and can plug reservoirs. For each of these problems related to contaminants, reliable filtration and separation steps are critical to main - taining low operating expenses. Filtration and separation products for solvent clean-up are well known due to dec- ades of experience with gas treatment. However, other applications, such as feed treatment before CO₂ capture processes, solvent emission prevention, and downstream, including dense-phase CO₂ purification are less known, emerging applications in this sector. Pall applications in solvent clean-up, feed treatment, and solvent emission prevention are shown in Figure 1 , with detail in Table 1 . Applications downstream and in dense-phase CO₂ purifi - cation are shown in Figure 2 , with details in Table 2 .

Filtration and separation recommendations for select process locations in Figure 2

# 1 2

Need

Driver

Separation solution Liquid-gas coalescer

Remove solids and liquids on inlet Remove solid contaminants from lube oil

Compressor protection

Keep lube oil clean, reduce compressor Particulate filter or vacuum purifier

component wear Compressor vent

Prevent compressor cavitation (depends on compressor) Keep TEG/dehydration loop process

Vent filter, also called a ‘breather’

Prevent lube oil carry-over to TEG

Liquid-gas coalescer

dehydration loop

efficiency high

5 6

Remove solvent carry-over

Protect downstream compressor

Liquid-gas coalescer

Remove contaminants from supercritical CO₂ Remove contaminants from displaced water

Prevent reservoir fouling Prevent reservoir fouling

Absolute-rated particulate filter Absolute-rated particulate filter

8-9 See applications 4-5 in solvent carbon capture, Figure 1.

Table 2

PTQ Q1 2024