Cost Effective Pre Filtration for Naphtha Hydrotreating 

Types of Filtration Issues

Particulate Contamination

Particulate contamination is one of the primary filtration issues in naphtha hydrotreating. Solid particles, such as catalyst fines, rust, and insoluble organic compounds, can clog filters, reducing flow rates and causing pressure drops. These particles can originate from upstream processes, equipment corrosion, or degradation of the catalyst.

Water Contaminants

Water can be a significant challenge in naphtha filtration. It can cause emulsification with hydrocarbons, leading to difficulties in separation. Water ingress can stem from upstream processes, equipment leaks, or condensation. Effective coalescing filters (SupaSep LLP) are necessary to manage water contamination, but they can be overwhelmed if water levels are excessively high.

Organic Contaminants

Organic contaminants, including heavy hydrocarbons and polymeric substances, can foul filters and impede the hydrotreating process. These contaminants can originate from various sources, such as upstream processing units, feedstock variations, or thermal degradation. Their presence can lead to reduced catalyst activity and increased maintenance requirements.

Impact on Process Efficiency

Filtration issues can significantly impact the efficiency and effectiveness of the naphtha hydrotreating process. Clogged filters can lead to increased pressure drops, reduced flow rates, and higher energy consumption. Additionally, insufficient filtration can result in catalyst poisoning, lowering its activity and shortening its lifespan. Consequently, the process may require more frequent shutdowns for maintenance and replacement of filters and catalysts, leading to increased operational costs.

Consequences of Poor Filtration Choices 

Filters are consumable products, and as such the focus for procurement departments is often 'we need to reduce the piece price of this filter'. The consequence of this short sighted approach can lead to multiple problems in production. Here are just a few:

• Additional maintenance costs due to more frequent filter change outs
• Lost production time. It isn't a quick process to change out filters in a 65 round housing. Up to half a days production could be lost 
• Inconsistent performance of filters making it difficult to predict the in-service life or plan for scheduled filter changes 
• Cost of stock holding a much higher number of filters
• The environmental cost of additional waste 
• Poor quality filtrate leading to contamination of catalyst beds on hydrotreater and subsequent substantial maintenance costs

The Problem 

The client initially approached us due to poor delivery times from the incumbent supplier and just wanted us to quote for a like-for-like replacement of the existing low cost string-wound filters. They didn't want to increase consumable costs. We will see later how wrong this type of decision can be!

Our approach as a company is always to try and improve the filtration process in terms of on-stream life , filtrate quality and OPEX.  Retrofitting like-for-like, although low risk, essentially negates any chance of process and OPEX improvements.

However, in this case it was urgent that the client secured a reliable supply of filters to keep the process going. When supply issues are a real problem it is understandable decision.  

Our SupaWind string-wound cartridge was supplied as a direct retrofit. Whilst performance was equivalent to the original system (filter lifetime 2-4 days when the hydrotreater was running at peak capacity) we felt this was not a viable solution long term.