Human having to make decision

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I recently shared with you P&ID’s Solid-liquid Separation Decision Matrix to help guide your decision-making process. Let me demonstrate how this this process development matrix benefited a recent specialty chemical application for a food additive.

Engagement background

The client’s current process uses several “Sparkler” manual plate filters with paper filter media including filter aid for a body feed and precoat. The process is an organic solvent slurry where the liquid filtrate is the product. Solvent washing and cake drying follows with a manual (dig-out) dry cake discharge. Finally, the solid particle size distributions (PSD) are fine in the range of < 1 micron to a D50 = 40 micron and are a low concentration in the 1% range.

In expanding the process, the objectives included meeting quality requirements while considering operator safety and addressing containment and throughput such that the selected solid-liquid separation technology didn’t become the bottleneck of the plant. These goals were further complicated by the incorporation of a new type of reactor / extractor technology.

Applying the Decision Matrix

P&ID’s decision-making tool considers three main components of material properties, mechanical properties of the technology, and separation technology performance. To use the Matrix, each relevant box is completed and then discussed. The ranked choices are then evaluated against operational, financial, and internal and external plant objectives.

In this case we first examined the material properties of the slurry including range of PSD, typical solids content of the slurry (% Solids), and the process characteristics. From this analysis and the P&ID Handbook of Solid-Liquid Filtration, we determined we needed clarification technologies such as:

  • Candle Filter
  • Pressure Plate Filter
  • Filter Press
  • Pressure Leaf Filter

Continuing with the Decision Matrix, we looked at separation technologies for containment and solvents. This eliminated the enclosed filter press design due to the solvents. Then, the pressure leaf filter was eliminated as a dry cake was required for maximum product recovery.

Continuing, as filter aid, both body feed and precoat, is necessary, we examined the cake structure of both the vertical candle filter and the horizontal pressure plate filter. Our discussion also had to consider critical parameters including washing efficiency and cake discharge as well as “batch” cleaning as this is a food additive. Finally, we had to explore the “wild card” in this expansion—the new reactor/extractor and the type of crystals it will produce.

Our decision-making also considered the Decision Matrix’s final deliberation points, the operational and mechanical components. That’s how we determined the horizontal cake structure was the critical factor due to the stability of the body feed/precoat, the washing efficiency, dry cake discharge, cleanability, and the ability to handle a large variability of feed slurry.

Decision-making in action

It was rewarding to me to evaluate technologies with the client using the Decision Matrix. It helped P&ID to move this client’s expansion process forward by working to select the appropriate technology supplier and conducting lab and pilot testing to develop a process guarantee for the expansion.

Let’s put the Decision Matrix to work for you. P&ID is ready to assist you for you solid-liquid separation, process drying and mixing/reacting processes.