Biltong plant’s optimal drying facility

By Andrew Minnaar and Michael Barbosa

Operating for decades and serving red meat products locally and internationally, Cavalier Abattoir raised the bar even higher with the installation of a biltong plant that sees over 20 tons of product going to market monthly.

Cavalier Group of Companies – located on a farm in Cullinan – is split into four entities, creating the shortest and most cost-effective route for red meat products from farm to fork. The Group is made up of Cavalier Foods, Cavalier Livestock, Cavalier Abattoir and Cavalier Feeders.

The Cavalier beef and lamb abattoirs are situated on the same premises as its packaging factories and feedlot. This is where the biltong plant is found that supplies ready-to-eat biltong to a high-end retail outlet nationwide.

Client brief

Cavalier sought Matbar to construct and SCIP Engineering Group to design a biltong plant supplying over 20 tons of dried biltong per week to the retailer. The design specifications were to fit an existing room with the appropriate equipment in order to dry 3 300kg of product in a 46-hour cycle. Upon examination of the existing plant, AMC Engineers (subcontracted mechanical engineers) discovered that the rooms had already been built based on an alternative design concept. The main challenge after the discovery was that AMC had to employ a different approach in order to achieve the correct room conditions and specifically the required airflow through the product.

All systems go

The project was always under immense time pressure as it was the result of a new supply contract. AMC was approached mid-August to assist with the design specifications of the room. Halfway into September a detailed investigation of the existing rooms, including temperature and humidity logging and reviews were completed. At the same time the detailed psychrometric analysis and coil selections were completed, and pricing of the equipment was underway.

The design included a significant amount of research into the literature and theory around biltong drying and optimising the process from a product quality perspective. AMC prides itself in being able to analyse and research speciality system and processes in order to ensure that the optimal solution for the client is proposed. This is then tailored to fit budgetary and timeline constraints of the project.

HVAC system

The system design ensured that the room temperature and relative humidity were maintained throughout most of the drying period. The exception was the first few hours of peak moisture removal during which the system removed most of the moisture. This was done at slightly elevated conditions for a short period of time to optimise the capital equipment costs and also the operational cost of the unit.

The system further incorporated the correct air filtration strategy for a food safe environment, specifically considering that the final product of this process is ready to eat. For the air handling unit (AHU), a primary, secondary and tertiary filter was specified.

The design included a significant amount of research into the literature and theory around biltong drying.

A critical aspect of the system design is the appropriate selection of the materials of construction to suit the application and the filtration to allow the system to comply with internationally accepted food production standards. AMC has significant experience in the industrial and food processing air conditioning environment and prides itself in providing optimal and appropriate solutions to clients that facilitate the production process from a temperature, relative humidity and air quality perspective.

The AHU coil design was approved on 30 September 2019 and rigged into position on 18 October, just under three weeks from the approval date.

On 17 November the first load of biltong was placed in the room to trial its performance. This was owed to the fact that, during all commissioning phases, there was some fine tuning and fault finding to be done on the system once it was operating under load. By 28 November most of the commissioning niggles were resolved and the first batch of high-quality product was dried in the room.

Dealing with challenges

One of the most challenging aspects of this project was the timeline and the fact that this precluded the utilisation of any desiccant dehumidification equipment due to equipment lead times. The dehumidification and room conditioning were achieved purely by mechanical dehumidification and reheat.

In order to achieve the correct amount of airflow over the product a false ceiling plenum was constructed and either side of the room was fitted with perforated stainless steel plates to allow for the equal distribution of air from one side of the room to the other. This is critically important to ensure that the product dries evenly and consistently across the entire room and thus ensure a superior product.

Savings from the system

Due to the significant time constraints on the project there was not sufficient time to optimise and look at all possible energy optimisation strategies. AMC did however perform a review of future potential optimisation and have allowed for these in the design at minimal initial cost.

Some of these strategies include the use of waste heat from the ammonia plant for primary reheat of the dry off coil air as well as the utilisation of external ambient air under specific conditions to reduce the dehumidification load on the AHU. In some instances that ambient air absolute humidity content is low enough to be utilised directly under 100% fresh air conditions.
Although no ducting or coils were installed for the above potential modifications, space was left for these in future in the form of a fresh air damper and physical space in and around the AHU.

One of a kind system

What made this project special is that it was completed under stringent time constraints; the contractors and equipment suppliers worked extremely well as a team; and the client in the end had a well-designed and installed system that operates as required and optimally. It was a great sense of achievement to hear from the client that their customer was happy with the quality of the final product and that internally they were pleased by the performance of the room as a whole.

There was a significant improvement in the final product due to the correct drying regime and room conditions.

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