Quality and consistency are a priority for food service supplier J.S.Bailey. Expertise, care and attention all go into the production of the cheese that they supply across the UK and Ireland. Committed to creating a facility that meets the highest possible standards, and that would increase production and drive business growth, in 2019 they invested £3m to expand the production facility and create an additional purpose-built storage unit with the capacity to store up to 1000 tonnes of product.
Robust controls are embedded at each stage of production at J.S. Bailey. The expansion project delivered by Personal Refrigeration (PR) mirrors this with the installation of a high-tech refrigeration plant complete with custom control algorithms to serve multiple HT areas.
In light of the client’s substantial investment, it was agreed that the design should be focussed on precision control, reduced operating costs, increased system longevity and user-friendly functionality to ensure the greatest possible payback. Two identical HT refrigeration packs, each utilising three Frascold semi-hermetic compressors, serve a number of evaporators within the storage, holding and production areas.
The high-efficiency evaporator coils reduce the refrigerant charge by 15%, minimising the system’s environmental impact. Sharing the load between two packs provides contingency, eliminating costly downtime and product spoilage due to a single-point failure. A quad circuit heat recovery tank supplies hot water to various factory processes using an anti-legionella flush program as necessary.
The commissioned installation benefits from inverter-driven compressor PLC algorithms, with fully independent compressor modulation for step-less and seamless loading from 11–77 kW per pack. The refrigeration plant precisely matches the ever-changing real-time load conditions, which ensures that only minimal energy is consumed.
It has been proven on previous installations of a similar nature that PR customers are being rewarded with up to 35% lower running costs when compared to equivalent fixed-speed systems. Custom Software Programmes Dual adaptive PID loading/ unloading algorithms measure real-time load demand and react accordingly to the current suction pressure set point. Initiation of the refrigeration pack loading ensures that the compressor with the lowest run hours is always selected to start first via the primary PID loader.
The secondary loader then allows the compressor modulation algorithm to run, modulating through its range to satisfy the set point suction pressure. In turn, the primary loader will continue to run in the background, monitoring the load and starting another compressor when the full modulation of the running compressor is reached.
An additional compressor will only be allowed to start if the set point suction pressure cannot be satisfied utilising the running compressor whilst modulating through its range. The compressor modulation algorithm will then consider the independent compressors that are operational. This is performed over a cyclic period.
- If load increase is required, the compressor with the lowest frequency will be increased in speed, providing more refrigeration capacity.
- If load decrease is required, the compressor with the highest frequency will be decreased in speed, reducing refrigeration capacity.
The dual adaptive PID loading system also ensures that compressor wear and tear remains even whilst running in reverse. Compressor stop will be initiated only when modulation of running compressor(s) is below a set threshold but inversely choose the compressor with the highest run hours to be turned off first. Constant adjustment of compressor modulation also ensures that frequencies of running compressors are balanced whilst in operation, along with running hours via the primary loader.
The above dual adaptive loading system ensures both step-less and seamless load matching, and more importantly, provides the end user with energy savings during plant operation.
Personal Refrigeration have been writing PLC programs and pioneering algorithms on the RDM TDB platform for over 6 years and is continuously seeking to develop groundbreaking ideas to improve plant operation and efficiency.
New features and technologies are integrated into their designs to provide clients with energy-efficient, cost-effective and environmentally responsible installations.
- 2x PR0650TDB Intuitive controllers with custom pack software.
- 4x PR0652TDB Intuitive controllers with custom HT evaporator software -> HT steppers to drive EEV with a custom diver & Frost prediction algorithm.
- 1x PR0680TDB Mini Intuitive controller with custom heat recovery software.
- 1x DMTouch for site monitoring.
The installation features energy monitoring with predicted running costs, using a DMTouch algorithm, and uses high-efficiency condensers with reduced refrigerant volumes.
Energy savings for this site as a whole have been estimated at 30%, by analysing compressor running times, reduced system load and defrost costs.
“Personal Refrigeration designed and delivered a high specification project using RDM solutions that will provide the business with low operational cost chilled storage for years to come.” Project Manager, JS Bailey
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