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Sara Lee

Sara Lee has been making a wide range of desserts using Australian produce for the past 40 years. Throughout its history, the production facility in Lisarow, NSW has operated several food production and processing lines, including bakery, fruit processing and frozen food production. The consists of two separate ammonia refrigeration plants – one with only spiral coolers, and one with spiral coolers, blast freezers and freezer stores.

Previous improvments

Minus40 has been working with Sara Lee since 2010 to implement a series efficiency improvements and safety upgrades. This has resulted in achieve energy savings of 10-30%.

The biggest improvements came through optimising load distribution between the site’s multiple compressors. There are four high-stage and four low-stage compressors in plant room 2, and a further three compressors in plant room 1.
Previous improvements

Variable Speed Drives (VSDs) had already been installed for some of the compressors, but others still used slide control. This type of control is only efficient when the compressor is operating at 100% capacity. Installing compressor staging and capacity control provided a worthwhile energy saving by ensuring that compressors are each being operated at their maximum efficiency at all loads.

New recommendations

In 2012, Minus40 recommended improvements for further energy savings. The recommendations led to a Clean Technology Investment Program (CTIP) grant being awarded in 2013. This included expanding on the compressor staging and capacity control and variable head pressure control in both plant rooms, as well as fan speed control for the condensers in plant room 1, and for the evaporators in plant room 2.
Implementation

Variable speed drives and other control devices needed to be monitored throughout the Sara Lee plant. This involved installing sensors at some locations, and connecting all sensors to the PLC. Some pressure and temperature sensors also needed to be connected to the PLC via transmitters.

Refrigeration Plant No. 1:

  • Installation of VSD for evaporative condenser No. 2
  • Replacement of electric motor for compressor No. 1
  • Installation of VSD for compressor No. 1 (removed from compressor No. 4 of refrigeration plant No. 2)
  • Implementation of VHPC (variable head pressure control) and CSCC (compressor staging and capacity control) logic


 Refrigeration Plant No. 2:

  • Installation of a new automatic air/water purger
  • Replacement of electrical motor for compressor No. 5, No. 6 and No.8
  • Installation of high stage screw compressor economising package and upgrading of existing undersized pipe-work
  • Installation of VSDs for freezer store evaporator fan coil units
  • Implementation of VHPC, CSCC for both high stage and low stage compressors, EFSC (evaporator fan speed control)

 

Fonterra Wagga Wagga

Fonterra is a New Zealand-founded global dairy company with a global milk distribution of 22 billion litres of milk annually. The company’s site at Wagga Wagga is the Riverina’s only milk processor, with its Riverina Fresh brand providing white and flavoured milk, yoghurt and dairy desserts.

Refrigeration: critical process

Many of the processes at the Wagga Wagga site require refrigeration. The refrigeration plant is responsible for most of the site’s energy consumption. Minus40 found opportunities for significant energy savings with this equipment through improved efficiency.

A study done by Minus40 in 2010-11 found that the existing refrigeration plant design was ad-hoc, consisting of an ammonia chiller, an R22 chiller and also multiple individual Freon circuits. Many opportunities for improvement were identified, but the R22 chiller was found to be the most energy-intensive component.

R22 Chiller Replacement

The Wagga Wagga site was scheduled for increased production, but the existing refrigeration plant did not have capacity to support the increase. A chiller upgrade was inevitable, so it provided a compelling opportunity for efficiency improvement as well as capacity increase.

The existing R22 chiller was required to act as an “ice bank” - a practice in which the chiller produces ice during periods of low load, so that it can use this stored energy during peak load. This is a particularly inefficient practice – it is preferable to operate a chiller with capacity for peak load.

Replacing the R22 chiller also presented an opportunity for a much better environmental outcome. R22 is a type of HCFC (Hydro-chlorofluorocarbon) which is a substance with powerful ozone-depleting characteristics. It also has an extremely high Global Warming Potential (GWP) of 1780, indicating that the global warming effect of R22 is 1780 times larger than that of carbon dioxide. These two properties of R22 refrigerant are the reason for its phase-out.

These considerations led to a solution with a new chiller run on ammonia. Although the unit is larger than the original unit, it is more efficient and has a far smaller environmental footprint.

Ryan Meat Company

Ryan Meat Company is a medium-sized abattoir in northern Victoria, specialising in red meat processing and sales to local meat wholesalers and butcher shops. The business has been in operation for 60 years, but following growth in the business, a desire to export, and rising power costs, there was a push to improve energy efficiency.

The Brief

Minus40 has been commissioned by Meat and Livestock Australia (MLA) to investigate a commercial to industrial refrigeration upgrade opportunities at Ryan Meat Company.

The refrigeration system is responsible for a large part of the company’s energy costs, so it was an obvious target for efficiency improvements.

While the existing equipment was relatively clean and leak-free, a study by Minus40 revealed the plant was no longer operating at maximum efficiency. It had reached the end of its service lifetime, with insufficient capacity for the planned increase in production from 22,614 kg per day to 55,000 kg per day.

The system used a variety of synthetic refrigerants (including R22, R134a, R404a and R408a) having a high global warming potential. R22 (Freon) and R408a are ozone depleting refrigerants and are being phased-out under the Montreal Protocol resulting in actual price rising and availability restricted. Simply replacing the worn and inefficient components was not an effective solution. Instead, the study recommended replacing the entire refrigeration plant, providing greater capacity, improved efficiency, and eliminating environmentally harmful synthetic refrigerants.

Plant Design

Minus40 recommended installation of a central liquid recirculation two-stage ammonia refrigeration system, with evaporative condensers. The carcase chillers and runner chiller are now served by medium-temperature ammonia. The new blast freezer is served by low-temperature ammonia. The system uses only natural refrigerant, ammonia – synthetic refrigerants have been completely eliminated. Ammonia has a zero Global Warming Potential (GWP) and zero Ozone Depletion Potential (ODP), ensuring the system presents no environmental risk if the refrigerant leaks.

The upgrade included a comprehensive automated plant control system, which enabled the plant to be operated optimally for best energy efficiency.

Variable Head Pressure Control

Variable head pressure control was implemented at Ryan’s meat company to increase energy performance of the ammonia plant. While most refrigeration plants maintain a constant head pressure, efficiency is improved by maintaining the head pressure at the lowest possible value, which is based on the ambient conditions:

  • Higher head pressure during peak load and hot/humid summer conditions.
  • Reduced head pressure during periods of reduced load (such as when the ambient temperatures are lower, or there is lower production)

Reducing head pressure lowers the compressor power consumption, but requires an increase in condenser fan speed, and hence an increase in fan power consumption. The head pressure must be continuously varied to ensure both fan and compressor power consumption are minimised.

 The minimum point is dependent on the plant’s instantaneous load, and the wet bulb temperature. Load is calculated by the plant control system. Wet bulb temperature is determined by measuring ambient dry bulb temperature and relative humidity. With the appropriate sensors installed, the control logic is then programmed to calculate the head pressure set-point, and then operate components as necessary to achieve the set-point. Based on the desired head pressure, the control logic determines the appropriate fan speed. For this to be feasible, the condenser fan must have a Variable Speed Drive (VSD) installed, enabling smooth variation of speed.

Heat Recovery

Ryan Meat Company uses a large amount of hot water on site for sterilisation, wash-down and boot-wash. Previously, town water was pre-heated in electrically-powered by 35 R134A heat pumps. Final heating in the hot water generator was powered by LPG.  The new Ammonia plant’s waste heat is now used to pre-heat town water.

Heat recovery was achieved by installing:

  • plate-type heat exchanger (which heats water using the waste heat of the high stage compressor)
  • insulated hot water tank to store hot water
  • necessary pipework and water pumps.

The amount of heat available varies according to the refrigeration plant operation. A variable speed driven pump was installed to pump water between the tank and the heat exchanger, with the speed varied to maintain constant hot water temperature. Another VSD pump was installed to pump water between the hot water tank and the boiler, where the speed was varied to maintain constant pressure.

 Speed of the pump between the hot water tank and the hot water generator is controlled to maintain a constant supply pressure. The control system ensures that hot water delivered by the heat recovery system has constant temperature. The large volume storage tanks also ensures there is always sufficient hot water to meet demand by the hot water generator.

Evaporator Fan Speed Control

 At higher fan speeds, a one percent reduction in fan speed results in a three percent reduction of its power consumption. Consequently, a moderate reduction in fan speed can provide a surprising reduction in energy costs.  Fan speeds of 100% are only required during periods of maximum refrigeration load. During periods of lower room load (such as during ‘carcase holding’ mode), the fan speed can be reduced with no effect on cooling.

The plant control system has been set-up to operate different fan speeds during various stages of carcase chilling, ensuring maximum possible efficiency. Reducing fan speed also reduces associated load on the refrigeration plant, thus reducing compressor power consumption.

Implementation and Energy Savings

Replacement of the old Freon units, along with improved control techniques, was expected to provide an energy saving of 215 MWh per annum, accounting for 35.7% of the site’s power consumption. The upgrades were completed in June 2014 and were expected to save the site $50,000 in energy and maintenance costs per year. The proposed upgrades resulted in a successful Clean Technology Investment Program (CTIP) grant application, which assisted in funding the project.  In October 2014, Measurement and verification indicated that the plant already exhibited an annual energy saving of 163 MWh, which represents 27.1% compared to 2013. Further optimisation of the variable head pressure controls is expected to continue to increase the energy savings.

The unreliable R134A heat pumps are no longer used, with a resulting drop in power consumption. Water at 55-60oC is provided to the boiler, reducing LPG consumption by 10.4%

As a result, replacing their old refrigeration system by an efficient ammonia system and recovering the heat to produce hot water allowed Ryan Meat Company to save $ 51,694 per year.

Radevski Coolstores Low-Cost Finance

Radevski Coolstores is a family owned and operated business, and a major Goulburn Valley supplier of apples and pears to Coles Supermarkets. As experienced growers, the family members are involved in every aspect of the business from marketing, orchard and pack house management, to quality control and dispatch. Radevski Coolstores has grown from one orchard in 1959 to its present 450 acres of apple and pear orchards, in the productive heartland of Goulburn Valley’s Shepparton East district. Its turnover is around 20,000 bins of fruit per year. Increasing energy and refrigerant prices have significantly increased the business’s operating costs.

Project Details

To beat rising energy bills, Radevski Coolstores is undertaking a $1.15 million refrigeration upgrade of its cool rooms. A new ammonia-based refrigeration system servicing its 16 cool rooms, will reduce those costs by over $140 000 and will also take advantage of improvements in refrigerator design to reduce carbon emissions by 24 per cent.

The project, being carried out by Low Carbon Australia strategic alliance partners and refrigeration specialists MINUS40, will involve upgrading the plant to operate on ammonia refrigerant and the implementation of condenser fan speed control, to further improve the system’s energy efficiency and performance.

RWTA member company MINUS40, did the design and facilitated the contact between Radevski Coolstores and LCA/CBA. The Radevski project was used as a trial project to perfect the LCA/CBA product, which is now fully available. This finance product currently appears to be the cheapest on the market (by up to 2%, depending on client), but an energy audit/business case report is required to qualify. It is also much easier and less cumbersome to access than direct LCA finance.

MINUS40 can assist with accessing this facility as they are now working directly with the finance product management team at the Commonwealth Bank.

Commonwealth Bank, Low Carbon Australia and Clean Energy Finance Corporation

The nation’s largest bank, Commonwealth Bank of Australia Ltd, is working with Low Carbon Australia under a ground breaking agreement for financing Australian manufacturers and businesses to reduce their energy costs.

By working together, Low Carbon Australia (LCA) and Commonwealth Bank (CBA) present a unique offer that is a clear demonstration of the Bank’s commitment to remain at the forefront of financial innovation, for the benefit of its clients.

The boards of Low Carbon Australia and the Clean Energy Finance Corporation (CEFC), have announced an in principle agreement to integrate Low Carbon Australia into the CEFC, which will commence investment operations from July 2013.

MINUS40 Project Services

MINUS40 assisted Radevski Coolstores with the following project services:

  • Project identification, conceptual design and feasibility study
  • Selection of critical equipment such as compressors, condenser, evaporators and vessel sizing.
  • Work scope documentation preparation
  • Tender management process
  • LCA Funding application assistance
  • Project measurement and verification (upon project completion)

Rivalea Energy Efficiency Upgrade

Rivalea is an Australian agri-food company based in Corowa NSW, with activities in feed milling, livestock production and meat processing..

The processing facility uses an ammonia refrigeration plant, which initially had an annual power consumption of 5.164 GWh. There were numerous opportunities for energy savings identified by Minus40 at Rivalea. Some of these were implemented in early 2013, with estimates of a 10-30% energy saving for the refrigeration plant. The improvements are outlined in this study.

Project Details

Compressors produce a lot of heat – heat which is wasted in typical refrigeration plants. On a meat processing site such as Rivalea, there is high demand for hot water, including wash-down water. At these sites, the “waste heat” is valuable.

To recover the heat, it was necessary to install a high stage discharge desuperheater, and also heat recovery oil coolers onto two high stage screw compressors. Only two of the compressors operate for long enough periods to make heat recovery feasible.

The solution uses two stages of heat recovery; first the water is fed through the discharge gas desuperheater, and then it is fed through the oil coolers for further heating.

Variable speed drives for fans and compressors were added so that motors were run only to the power required, rather than always running at full power. Monitoring was installed for all variable speed drives.

The Rivalea upgrade project benefitted from the Minus40 whole-of-project expertise to attract the following benefits:

  • NSW Government Energy Saver Program – this covered part of the cost of the initial audit, which established the feasibility of the resulting upgrade.
  • Low Carbon Australia (now Clean Energy Finance Corporation) – this provided low-cost financing for the upgrade work.
  • AusIndustry Clean Technology Investment Program – a co-contribution towards the upgrade.

MINUS40 Project Services

MINUS40 assisted Rivalea with the following project services:

  • Project identification, conceptual design and feasibility study
  • Detailed engineering design
  • Provision of functional descriptions for plant control logic
  • Tender specification preparation
  • Tender management process
  • CTIP grant application assistance
  • Project measurement and verification (upon project completion)

Project Funding

Throughout the project, MINUS40 assisted Rivalea in acquiring the following financial project assistance:

  • OEH Energy Saver Program: Subsidised 70% of feasibility study
  • Clean Technology Investment Program: $268,810 CTIP Grant

GM Scott

GM Scott is a privately owned meat processor based in Cootamundra, New South Wales. Established in 1952, it now employs 200 staff, making it Cootamundra's largest employer.

The abattoir processes 3,500 lambs and 200 cattle daily. It's gas-flushed, cryovac sealed lamb products are sold into export and domestic markets, while its fresh beef and lamb are produced under the Noble Farm brand. The factory also processes boneless legs of lamb and frenched racks for NSW Woolworths supermarkets.

Project Details

The current refrigeration systems at GM Scott consist of a newly-built ammonia plant and a separate plant operating on R-404a refriferant. The ammonia refrigeration plant consists of a single stage arrangement for the medium temperature loads and an economised across line arrangement for the low temperature loads.

The plant serves various chiller rooms, the load out, plate freezers and a freezer store. The R-404a refrigeration plant operates in a single stage economised arrangement and provides cooling to other chiller rooms, a carton chiller and a packing and boning room.

MINUS40 proposed the implementation of the following energy efficiency upgrades for the ammonia and R-404a refrigeration plants:

  • Ammonia Plant - Variable Head Pressure Control: The installation of condenser fan VSD's and implementation of an intelligent control logic varies the refrigeration plant's head pressure set-point to minimise the total plant's power consumption as a function of plant load and ambient conditions. An additional advantage is that it stabilises the plant's operation.
  • Both Plants - Evaporator Fan Speed Control: The evaporator fans in both freezer rooms and carcass chillers are fitted with VSD's and a suitable speed control logic is implemented. The control logic was specifically designed for each room, in an effort to minimise fan speeds without compromising production and meat quality. Lowered fan speeds significantly reduce fan power consumption and reduce the overall heat load in the room.

MINUS40 Project Services

MINUS40 assisted GM Scott with the following project services:

  • Project identification, conceptual design and feasibility study
  • Provision of functional descriptions for plant control logic
  • Work scope documentation preparation
  • Tender management process
  • CTIP grant application assistance
  • LCA funding application assistance
  • Project measurement and verification (upon project completion)

Project Funding

Throughout the project, MINUS40 assisted GM Scott in acquiring the following financial project assistance:

  • OEH Energy Saver Program: Subsidised 70% of feasibility study
  • Clean Technology Investment Program: $85,373 CTIP Grant
  • Low Carbon Australia: Additional LCA-supported loan

Crafty Chef

Through the implementation of a new freezing process, Crafty Chef, a Western Sydney Food manufacturer, will be able to double the current production levels with a significantly more efficient system.

Project Details

Prior to this project, Crafty Chef's blast freezing systems consisted of commercial air-cooled refrigeration systems running on R-507 refrigerant. A significant capacity increase of the system was required as the production levels of the facility were doubling.

Minus40 analysed several opportunities to increase system capacity whilst increasing the energy efficiency of the plant. Based on the results of this study, the decision was made to replace the existing commercial systems with an industrial spiral freezer system running on ammonia (R-717) refrigerant.

The proposed system incorporated the following features:

  • Ammonia Refrigerant: Being an environmentally benign and highly efficient refrigerant, the system is able to drastically reduce greenhouse gas emissions, indirectly through reduced energy consumption and directly through the mitigation of R-507 refrigerant leakage (R-507 is a very strong greenhouse gas).
  • Speed Controlled Industrial Screw Compressor: With the installation of a VSD on the compressor motor and the implementation of the appropriate control logic, the system is able to achieve a high system efficiency, even in part-load operation.
  • Variable Head Pressure Control Logic: Through condenser fan speed control and optimisation of the head pressure set-point in function of ambient conditions and system load, the system takes advantage of low load and ambient temperatures to reduce energy consumption.
  • Heat Recovery System: Heat is recovered off screw compressor oil and used to preheat water going into existing boilers.
  • Evaporator Fan Speed Control: Allows total air flow control to control product cooling and reduce fan energy consumption.
  • Spiral Freezing System: The spiral freezing process allows for increased capacity, continuous production and consistent product quality.
  • Evaporative condenser: Evaporative condensers significantly reduce energy consumption and demand compared to air-cooled systems.

Minus40's Project Services

Throughout the project, Minus40 assisted Crafty Chef with the following:

  • Feasibility study, including data monitoring, system modelling and business case development
  • Engineering support and project management during installation
  • Technical verification of contractor installation
  • Supply of functional description for plant control logic
  • LCA Funding and CTIP Grant applications (see below)
  • Energy measurement and verification (upon project completion)

Project Funding

Minus40 assisted Crafty Chef in sourcing funding for the $1.12 million project from several Government Programs:

  • OEH Energy Saver Program: Subsidised 70% of feasibility study
  • Clean Technology Investment Program: $500,000 CTIP Grant
  • Low Carbon Australia: Additional LCA-supported loan

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