Australian technology transplant

by Emily Wilson
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Bunker-type storages, often referred to as open bulk head or open flat storages, are well suited to drier, more temperate climates and are widely used in Australia. The Menoyia Bunker Field represents the "transplanting" of the Australian experience in Cyprus.

Menoyia Bunker Field, developed by the Cyprus Grain Commission (CGC) with the assistance of Australian grain handler, AusBulk Ltd., features some of the latest advances in inexpensive bunker storage technology used in Australia and is the result of a five-year collaboration between the two organizations.

Faced with the need to increase the grain storage capacity of Cyprus in a relatively short time and at low cost, delegates of the CGC visited Australia in 1996 to examine the country’s various bulk handling systems and were impressed with developments in AusBulk’s storage network in South Australia.

"AusBulk is one of the experts and a pioneer in grain storage bunker technology," the CGC’s Dr. Andreas Varnava said. "This was a good guarantee for the successful introduction of Australian bunker technology into Cyprus."

AusBulk at the time was modernizing its extensive network of 111 grain receival sites and seven export terminals in preparation for projected production rises and increasing rates of harvest in South Australia. In addition, AusBulk was working in other Australian states to develop cheap and efficient receival sites, based on bunker-type storages, using mobile loading systems as an alternative to fixed-plant storage systems.

AusBulk embarked on its A$150 million ‘strategic site’ program, upgrading 33 key sites in South Australia state to increase storage, intake and outturn capacity to accommodate a series of record harvests from 1995 to 1999. Important features of the strategic sites included an on-farm pick-up freight service to influence grain deliveries towards the sites and away from less-efficient silos, thereby minimizing AusBulk’s operating costs. Mobile drive-over hopper (DOH) stackers were used to load grain into bunkers which could be moved from site to site to increase intake capacity where needed during the hectic South Australian harvest.

Witnessing the changes taking place in South Australia, in particular the use of aeration systems and phosphine fumigation in AusBulk’s bunkers, the CGC asked AusBulk to develop a proposition to construct a similar bunker site in Cyprus. AusBulk personnel visited Cyprus in 1998 to examine proposed sites for the facility and to develop designs. Facility layouts were refined in AusBulk’s design office in South Australia.

"One of our main targets in developing Menoyia Bunker Field was to minimize or exclude the use of liquid insecticides and methyl bromide in the grain protection system by using only phosphine and aeration," CGC general manager, Charalambos Archimandritis, said. "We also sought to take advantage of probable low prices in the international grain market, which is important for countries like Cyprus, which depend on grain imports."

Planning and implementation

In 2000, the CGC put the Menoyia Bunker Field project out to tender and AusBulk was chosen ahead of six other tenders worldwide to assist in developing the site in 2001.

AusBulk engineer and project leader, Wayne Owens said a great deal of preparation went into the 2001 trip to Cyprus. "The plan was for AusBulk to build and operate a bunker while training the local people in their construction and operation," Owens said.

The AusBulk team, consisting of Wayne Owens, machinery specialist Barry Dawkins and operations specialist Peter Weaver, took with them to Cyprus all of the construction materials for six 10,000 tonne capacity bunkers, a self contained mobile DOH stacker (specially built in South Australia so as to fit into a standard shipping container), aeration systems, data loggers and even personal phosphine monitors. The entire shipment required 14 shipping containers and exquisitely timed planning to ensure the project met time and date constraints in two widely separated locations on the globe.

Owens said the AusBulk team worked well with the CGC project team, comprising mechanical engineer John Potsos, Dr. Varnava and electrical technician John Leandrou.

"The language barrier was the only problem but we picked it up quite quickly," he said.

AusBulk’s stay was swift, arriving in May 2001 and leaving the country in June with an operating bunker site. It was a testament to AusBulk’s ability to develop storage as quickly overseas as it had consistently been able to do in South Australia during unprecedented record harvests. AusBulk has on several occasions mobilized designs and resources to build more than a million tonnes of bunker storage capacity in less than three months to accommodate large harvests.

"We set up and operated a bunker on our own, then supervised the Cypriots in building another," Owens said. "The CGC then built the remaining four bunkers on their own.

"The only major adjustment we had to make to local conditions was to accommodate Cyprus-origin barley, which is significantly lighter than South Australian barley. The DOH stacker was rated at 300 tonnes per hour based on 0.75 tonnes per cubic metre, but we found that Cyprus-grown barley weighed only 0.5 tonnes per cubic metre. We could maintain the volume but not the tonnage."

Innovative aeration

Menoyia Bunker Field now features six sealed bunkers with a total capacity of 70,000 tonnes. Each bunker is 130 meters long, 30 meters wide and about 10 metres high, set on an east-west axis (west is the main direction of wind). Bunker walls are formed by a series of joined corrugated steel walls, each three metres long and 1.3 metres high, with fabricated ‘A’ frame support. Walls are secured to the ground by pegs through the frames.

The bunker base consists of compacted crushed rock of 200mm thickness. Before filling the bunker with grain, the base is covered with a 200-micron thick polyethylene liner. Walls are covered with polyethylene-coated fabric, which extends from the ground and interlocks with the top tarpaulin to create a structure sealed from liquid and gas.

When the bunkers are full, the grain is covered with 520 micron thick reinforced PVC, not permeable to water, oxygen, carbon dioxide or phosphine.

"This cover successfully withstood storm winds of 20 to 25 meters per second and heavy rainfall of 70mm in one day," Dr. Varnava said. "The sheets have an ice-blue color, friendly to the environment."

Four 18.5 kilowatt fans of 2,100 liters per second air flow and 3,600 Pa static pressure are used for grain aeration of each bunker, controlled by a computer operating on the difference between the wet-bulk temperatures of the grain and the ambient air.

AusBulk developed the aeration systems in cooperation with Australia’s Commonwealth Scientific and Industrial Research Organization’s (CSIRO) stored grain research laboratory.

"Aeration of bunkers is an innovation and it is expected to minimize moisture condensation at the apex of the bunker, enabling the storage of grain with an initial moisture content higher than 12.5%," Dr. Varnava said. "The bunker is also an excellent structure for fumigation with phosphine; in fumigations of barley in two of the bunkers, the concentration of phosphine was maintained at 60 parts per million for 15 days. After fumigating, the grain is aerated to remove phosphine residue and reduce the difference in temperature between the grain and the ambient air."

The total cost for the Cyprus complex, including 17 hectares of land, was U.S.$1.8 million, equating to about U.S.$25 per tonne. The cost of construction and grain handling equipment amounted to about U.S.$8.50 per tonne.

"The cost was about seven times lower than the cost for building conventional flat sheds of the same capacity," Dr. Varnava said. "It was 15 times lower than the cost for metal silos and 25 times lower for concrete silos."

Eight people (one grain inspector, one person for weighing, two technicians and four workers) are required to either fill or empty one of the Menoyia Field bunkers, equating to about 650 to 700 man-hours during summer or 850 to 900 man-hours during winter, due to downtime from inclement weather. It works out to a cost of about U.S.$2 per tonne.

"In Cyprus, the combination of this storage with aeration technology, phosphine fumigation and good quality control and management has become essential for profitable and ecologically-friendly grain handling," Dr. Varnava said. "The bunker method of storage provides successful protection of grain against insects, rodents, birds and rain, and reduces the need for using liquid insecticides."

International demonstration site

CGC Chairman Christos Patsalides said several future developments of the Menoyia Bunker Field site are being considered by the CGC, including its use as an international demonstration site of Australian grain handling technology and the CGC’s co-operation in transferring the technology to other countries in the Mediterranean.

AusBulk looks forward to the relationship with the CGC, as Ausbulk is expanding beyond bulk handling to provide other services to the Australian grain industry, in particular as an innovative marketer of Australian grain.

"What has happened at Menoyia Bunker Field is the virtual transplantation of a South Australian grain receival site in a country on the other side of the world," AusBulk chief operating officer John Warda said. AusBulk possesses one of the most modern and efficient grain storage networks in the world, and we are pleased to share our experience, he added.