Case study

Hygienic Design: Fouling of Tomato Ketchup

The challenge

Increasing throughput without sacrificing quality or risking contamination is a problem faced by many food processing companies. With this in mind the food industry spends significant amount of money on Cleaning in Place (CIP), through both water supply/disposal costs and production line down-time. Reducing the length and regularity of cleaning cycles is the key challenge to reducing overhead without increasing hygiene risk.

Using analytical modelling techniques to predict fouling in pipework and process equipment will allow the food industry to develop hygienic system designs, reduce cleaning overheads and improve cleanliness.

Our solution

Computational Fluid Dynamics (CFD) is an advance analytical simulation tool used across many industries for the prediction of fluid flows. This tool has been used by Frazer-Nash Consultancy to predict areas of food process equipment where fouling is an issue. This has enabled the redesign of these components resulting in reduced fouling and improved hygienic design.

Ketchup, like most food products, is a ‘non-Newtonian’ fluid which means it has a complex viscosity and is prone to fouling. This makes it very difficult to predict how it will flow. The case study discussed here has investigated Tomato Ketchup flowing through a ball valve.

The first stage of our work was to build and validate a CFD simulation of flowing tomato ketchup. The Non-Newtonian properties of the ketchup were expressly programmed into the CFD model. Results were compared with experimental data and showed a very good correlation.

Having demonstrated that CFD can accurately simulate ketchup, we were able to model more complicated geometries. Starting with various 90 degree bends we illustrated how much fouling was generated relative to the radius of the bend. This enables choices to be made about system design to optimise it for hygienic design and minimise the need for cleaning. Finally a ‘mix proof valve’ geometry was modelled illustrating the complex fouling mechanisms of non-Newtonian fluids.

Benefits

Using this method, we can identify areas of pipe work geometry which are at high risk of fouling without the need for test rigs or in situ testing. It also allows the flexibility to analyse anything from a single component to an entire system.

As well as showing the areas which are at high risk of fouling, this technique can also be used to highlight areas where the cleaning process is least effective.

Fouling reduction and more focused cleaning allows optimisation of the cleaning process. This reduces cost as less water is required and cleaning time is reduced. It also reduces the risk of contamination.

Screenshot 2020 05 03 At 22.22.31
Mix proof valves

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