PTQ Q1 2024 Issue

Blowback valves

Clean gas pipe

Module

Clean gas chamber

Filter module

Dust hopper

Figure 4 Fine fly ash present in flue gas feed to a carbon capture process

Figure 5 Low pressure drop filtration testing. Left: test stand setup. Right: filter inlet following tests. Fine particulate contaminants are visible on the face plate

the tests is kept between 20-30 mbar, with an estimated pressure drop below 60 mbar for full-scale installations, which include piping and valves. Solid loading in the gas feed varied above 1 g/Nm³, with exceptionally low down- stream solid loading after filtration – well below 1 mg/Nm³. Removal efficiency is above 99%, even for sub-micron par - ticulates down to a 0.5 µm diameter and below. The next steps are to continue to prove performance at increasing scales. Emission prevention Aerosol emission management has been another major focus of carbon capture technology providers. In sol- vent-based carbon capture technology, SOx and fine (<1 µm) flue gas feed particulates are responsible for most of the solvent losses out of the vent, which have been found to reach more than 1,000 mg/Nm³. In contrast, desired levels are typically as low as possible to minimise solvent losses and environmental impacts, well below 10 mg/Nm³. A water wash mounted on the top of the absorber unit limits gas-phase solvent emissions, but particulates and SOx, which form H₂SO₄ aerosols, serve as sub-micron diameter droplet nuclei. Droplet nuclei can then grow to larger micron-sized droplets as they travel through the water wash section. In this application, like flue gas pretreatment require - ments, there is an extremely low pressure drop (<20 mbar, as an example) available due to pressure conditions near atmospheric. Again, Pall is developing a product to uniquely meet the low-pressure requirements, while removing fine aerosols with an exceedingly high-efficiency (>99% aerosol removal) separator, producing well below 1 ppmw down - stream and also providing a minimal footprint. The unique ability of this separator to meet high-efficiency removal requirements and a low desired pressure drop is a result of the material science used in its fabrication and in-house technical expertise. The product design allows liquid to drain off quickly and easily, similar to the industry-proven high-efficiency liquid-gas coalescers shown in Figure 6 . Downstream purification and dense phase CO₂ After CO₂ has been captured, it is dehydrated and com - pressed to a high pressure for transport and storage. After dehydration and compression, CO₂ reaches a high-pres - sure ‘supercritical’ or ‘dense phase’ state, with a high den- sity nearing that of a liquid and a viscosity nearing that of

costs of compressing large gas flows and near-atmos - pheric process conditions of flue gas feed to CO₂ capture processes. Low pressure drop filtration systems are often large, making their integration into existing plants a poten- tial challenge in terms of space constraints. They also do not always capture fine (<1 µm) particulates present in industrial flue gases, such as those shown in Figure 4 . Pall has recently developed a new low pressure drop par- ticulate filter to address this application. The system and overall operation are based on decades of experience with Blowback filter technology, where particle contaminants build up on the feed side of a filter. After a period, caked contaminants are ejected off the filter for collection or dis - posal at automated intervals via a short gas pulse in the reverse direction. Filters regenerate at separate times, such that most of the filters in the system provide continuous operation and filtration. Through regeneration, filters main - tain a long on-stream service life, and the pressure drop after solids are blown off reaches an equilibrium point. Blowback filter cartridges were conventionally cylin - drically shaped and made from inorganic materials such as metals or ceramics to withstand harsh process condi- tions and offer fine filtration ratings with good reliability. However, to achieve an extremely low pressure drop with an order of magnitude in the 10s of millibar, as requested by the CCUS industry, conventional blowback technology would need to be oversized and thus would not have been an economical solution and would have been challenging to fit into brownfield industrial plants. This new product development leverages recent advances in additive manufacturing (AM) to produce a remarkably high surface area filter element with minimal manual manufacturing, enabling bulk production of filters at a given time. The high surface area ensures a small filter system footprint to handle a given flow rate and pressure drop (down to <20% the size compared to the conventional product and similar alternatives), which directly translates to reduced infrastructure needs and production costs. The new filter design was optimised through iterations of advanced computational fluid dynamics (CFD) modelling, coupled with rapid 3D printing prototypes that were tested at a lab scale with representative test dust and varied blow- back cycle time to regenerate the filter. Larger bench-scale tests depicted in Figure 5 with multiple elements were performed internally at Pall and offer impressive results. The pressure drop across the filters for the duration of

PTQ Q1 2024