Chris Wallace, Senior Corporate Vice President of Technology, Filtration Technology Corporation, discusses amine filtration optimisation and how to avoid mistakes such as contamination.
Filtration and separation equipment is crucial for the reliability, economics and ultimately the success of any industrial fluid process. And the refining industry is no exception, as the stability and efficiency of the amine sweetening process is highly dependent on contamination control.
Amine systems are highly susceptible to solids contamination, and refiners are well aware that very small iron sulphide particles are the primary cause of foam stability while surfactants (such as hydrocarbons), are responsible for foaming tendency. While operators take extensive measures to mitigate corrosion and suspended iron sulfides in their amine systems, some level of it is inevitable, underscoring the critical role of properly sized filtration equipment.
Industry best practices for amine filtration exist, but vague guidelines often leave too much room for interpretation – leading to inadequately sized filtration equipment that fails to provide a sufficient level of filtration and/or manageable filter life, which can lead to extended upsets and high operating costs.
Two critical filtration factors
To ensure long-term amine health and prevent costly inefficiencies, refiners must focus on two critical filtration specifications on process data sheets when sourcing new filter vessels:
- Micron rating at a defined efficiency, verified by a reliable test method to ensure reliable effluent quality.
- Filter media flux rate limited to 0.5 gal./minute per ft2, preventing vessel undersizing.
By implementing these precise standards, refiners can safeguard their amine systems, reduce labour-intensive maintenance, and avoid the hidden costs of inadequate filtration.
Proper amine filtration specifications
The beta ratio or particle removal efficiency is necessary for accurately reporting filtration performance. These ratios must be based on defined conditions provided by a test standard – one accepted by the relevant industry. For general industrial filtration, it is our opinion that ASTM F795-88 (1993) is the most suitable standard for critical industrial processes requiring predictable contamination removal.
To accurately assess the targeted process equipment, the specifications should include the test method used to determine the micron rating, and the efficiency of the cartridge should be clearly defined. Filter efficiencies and filtration costs are media face velocity dependent, and the filter media flux rate is a particularly important parameter.
For solids filtration involving water-like fluids, the standard media flux rate of 0.5 gal./minute per ft2 or less is recommended.
We recommend the following filtration level should be used to meet the industry targeted total suspended solids (TSS) of <5mg/l considering the typical particle size distribution of contaminants in an amine system:
Rich amine:
- Full flow duplexed filtration (2 x 100%) with 10-micron beta 5000 (99.98% efficiency) based on a single pass filtration test standard such as ASTM F795-88 (1993) initial efficiency (also applies to lean amine) and ≤ 0.5 gal./minute per ft2 flux rate.
Lean Amine:
- Pre-carbon: full flow duplexed filtration (2 x 100%) with 10-micron beta 5000 (99.98% efficiency) and ≤ 0.5 gal./minute per ft2 flux rate.
- Post-carbon: downstream of the 20 - 25% slip stream though the carbon bed. Single vessels are acceptable but duplexed filtration (2 x 100%) is always preferred. Filters to be 5-micron beta 5000 (99.98% efficiency) to remove carbon fines and ≤ 0.5 gal./minute per ft2 flux rate.
A sizable economic impact
The economics of filtration processes are directly related to filter element design and most importantly, filter media flux rate. The lower the flux rate, the higher the dirt-holding capacity (DHC) or total volume processed, therefore longer filter life. Ignoring the direct impact filter media flux rate has on filter usage can be detrimental to operations and operational expenses.
Opting for a smaller vessel simply because it meets the clean pressure drop specification without considering media flux rate may reduce capital expenditure, but it will result in frequent filter change-outs due to lower solids loading capacity, which ultimately leads to high operating costs. These operational costs can be direct or indirect.
Why this matters
Properly sized filtration in the amine system is crucial to combating foaming, fouling and under-deposit corrosion, which can lead to costly downtime, inefficient acid gas removal and upsets in the downstream sulfur plant. Refiners must ensure correct micron rating, particle removal efficiency and flux rate in filtration to achieve good amine hygiene.
FTC’s innovative filtration and separation technologies are not only solving today’s challenges in refining but are also paving the way for greater sustainability in the industry’s future. By extending filter life, reducing waste, and improving effluent quality, the Invicta technology exemplifies a commitment to supporting the refining industry, providing refineries with the tools needed to enhance efficiency, reduce costs, and meet reliability and sustainability goals.