4 June 2016

Fast, energy efficient freezing with plate freezers

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This article appeared in International Meat Topics Volume 7, Number 2

For meat processors seeking a time and energy efficient solution to freezing their product, plate freezing offers an ideal solution.

In the 1990s, New Zealand based engineering company Milmeq pioneered the introduction of large scale plate freezing technology to the meat industry. Today the company designs, manufactures and installs the world’s largest horizontal plate freezers.
The most common method used worldwide for bulk freezing of meat is air blast freezing. Plate freezing provides an alternative solution that can halve the freezing time, significantly decrease energy consumption, reduce manual handling and enhance product shelf life compared with that seen in air blastfreezing.

Plate Freezers

Plate freezers feature refrigerant-filled plates which make direct contact with cartons of product to provide a rapid, energy efficient freeze.


The typical 48 hour freezing cycle of air blast freezers is reduced to 24 hours in plate freezers. This rapid freeze improves the refrigeration index (a measure of shelf life and a regulatory requirement) while the cycle time reduction reduces stock inventory and time to market.


The efficient freezing cycle of plate freezers enables meat processors to reduce the electrical energy used for to freeze their product. Replacement of a blast freezer with plate freezing typically provides energy savings of between 24-30%.


Another key benefit of plate freezing is the output of cartons with uniformly flat surfaces, which deliver space efficiencies in the palletising, container loading and distribution operations. Loading a greater number of cartons per container reduces producers’ transportation costs as well as their carbon footprint, delivering approximately 15% reduction in empty container movements.


Milmeq produces plate freezers in a horizontally stacked configuration, ideally suited to operations with a large throughput of cartons of a uniform size and shape. The plate freezers are custom designed, with capacity options typically ranging from 500 to 2,600 cartons.


Milmeq plate freezers are available in automatic, semi-automatic or manual configurations.


The fully automatic configuration features an integrated materials handling system providing a hands-free environment which improves operator safety, reduces handling and retention time, increases product throughputs and enhances inventory management.


A key component of the plate freezer is a desiccant dehumidifier. A stream of very low dew point air provides a slight positive pressure to the plate freezer enclosure, minimising frost build-up on equipment and sensor surfaces, and reducing the need for defrost.


Ammonia (NH3) refrigeration systems are typically utilised for large scale plate freezers, however they can be supplied with range of refrigerants including carbon dioxide (CO2).


Single Station Opening Model (SSO)


Plate freezer technology is continually improving, with the latest innovation from Milmeq being the Single Station Opening (SSO) model.

In this configuration, only one set of plates opens at a time to load or unload product, leaving the others closed to continue the freezing process.


The SSO model delivers up to 3.5 hours additional freezing time. Depending on production requirements, this can result in a greater product turnover or the plate evaporating temperature can be raised to gain a further reduction in energy consumption.


Milmeq CEO, Mike Lightfoot describes the SSO model as another world-first development that is reflective of the company’s dedication to innovation.


“As with a number of the leading technologies we have pioneered over the years, I would anticipate that in time the SSO plate freezer will be recognised as setting the industry standard for the freezing of meat product,” Mike said.


Case Study: Installation of Plate Freezers for Fletcher International Exports


Australian based company, Fletcher International Exports has recently installed three plate freezers at their Dubbo site.


Fletchers are Australia’s most integrated processor and exporter of lamb and sheep meat products, exporting to over 90 countries around the globe. They operate two processing facilities, one located in Dubbo, New South Wales, and the other near Albany, Western Australia.


Previously at their Dubbo site Fletchers used a combination of two plate freezers and an air blast freezer to freeze their product. With plans to increase their production throughput, they needed a solution to increase their freezing capacity to match this.


heir main objectives were to achieve a faster freezing time for their hot boned products to minimise bacteria growth and maximise shelf life, decrease their energy consumption and input costs, and to free up the space currently occupied by the blast freezer in the centre of their processing plant for future extensions to their processing line.


The solution to this was to install three plate freezers, each with the capacity to freeze 2,300 cartons in a 24 hour cycle.


The plate freezers all featured Milmeq’s latest design of lifting cradle with synchronised hydraulics, compact chain pusher technology and an independent servo drive to provide better control over speed and positioning of the cradle for loading and unloading cartons.