In refineries, this is often implemented by means of leaf filters, where the adsorbent is captured in metal screens with a defined mesh, building a filter cake. A significant amount of contaminants is also removed during this step. Particle size distribution of the material used for purification is key to achieving high flowrates when dealing with a high contaminant profile.
Industrial-scale filtration typically follows a four-step process as Figure 1 shows.
Industrial filtration in detail
- Precoating: It is essential to cover the metal sieve with high-quality bleaching earth. If the precoat is not well produced (e.g. contains trace contaminations, gums, or fines), it could significantly reduce the filtration cycle.