Gentle bulk handling of cocoa beans

The logistics provider Vollers BV invested in a new infrastructure at its Port of Amsterdam site. Designed for storing cocoa beans, HoogTij port terminal went operational just a short time ago. Here, three fully automated Demag process cranes handle the tropical seeds.

Customer

Amsterdam is home to the second largest port in the Netherlands, after Rotterdam. In Europe, it ranks sixth. More than 20 percent of the international cocoa harvest is handled right here on the North Sea Canal, where the Amstel river and the IJ bay flow into the IJsselmeer. That makes Amsterdam the biggest cocoa port in the world. A significant proportion of this volume is handled by Vollers Holland B.V., part of the Vollers Group founded in Bremen, Germany 90 years ago. With a team of 320 employees and 13 locations across Europe, the owner-managed company is one of the most experienced logistics specialists for transport, storage and processing of green coffee and cocoa in Europe.

It is fair to say that Vollers Holland B.V. is a seasoned cocoa professional. Vollers uses a large part of its 120,000 sqm warehouse facilities to store the valuable cocoa beans. This requires great care to ensure the natural product can later be processed and turned into cocoa mass, powder and butter. Yet, the logistics provider’s range of services extends beyond handling the sensitive raw material. Vollers also offers value-added services like cleaning and blending cocoa beans, as well as pest control.
Requirement

With the newly built terminal adding 75,000 tonnes, Vollers now boasts a bulk capacity of 250,000 tonnes in Amsterdam. To put the new storage facility into perspective: 75,000 tonnes of cocoa beans equals 1.5 billion bars of chocolate. Most of the goods are shipped to Europe in containers and by sea – mainly from the Ivory Coast, Ghana, Nigeria and Cameroon in West Africa. After the vessels are unloaded by crane, the produce is moved with mobile conveyor belts. Trucks are also employed to transport containers on additional routes. The conveyors deliver the goods to the storage bays, where a feeder bridge operating on a track underneath the crane level then feeds them to the designated compartments. The output conveyor installed on the feeder bridge minimizes the drop height, which helps to ensure gentle handling of the valuable goods.

The recently built HoogTij cocoa bean storage terminal comprises three quayside hall complexes, each measuring up to some 150 m in length. The halls have up to eleven storage compartments featuring concrete walls that measure up to ten metres in height. This arrangement ensures that various grades of cocoa can be stored separately. The cocoa beans are retrieved in each hall by a fully automated process crane. The cranes also perform tasks such as storing and retrieving as well as blending and ventilating the valuable goods.

Solution

Vollers’ project management team and Demag collaborated to engineer the automated material flow concept that is the basis of the crane system control to ensure it meets the requirements for efficient and cost-effective material handling with a high level of system transparency.

High handling speeds

The three fully automated process cranes each have a load capacity of 17 tonnes. In the three stores, they operate on crane runways measuring 150 m in length with a span of 37 metres covering the individual storage compartments. Each crane can retrieve 200 tonnes of raw materials per hour. To achieve this, the process crane approaches the storage compartment assigned by the system according to the store supervisors to pick up the specified quantity. Besides retrieving specific grades, the crane and conveyor system can create carefully selected blends. The positions of the cranes and the feeder bridges are also managed to ensure that any collisions can be avoided. To ensure the processes are completed swiftly, the cranes reach long and cross-travel speeds of up to 80 m/min with a maximum lifting speed of 45 m/min – or 70 m/min for partial loads.

Large volume grab

The cocoa beans in the store are gently picked up with a motor-powered clamshell grab. Boasting a capacity of 14 sqm, the grab is operated with a hydraulic control system featuring magnetic valves. Despite its impressive dimensions and high load capacity, the grab can be used for reliably weighing and handling smaller quantities. The quantities are continuously monitored and logged by the calibrated weighing system installed on the trolleys.

Variable drives for smooth crane operation

Demag uses Dedrive-Pro 880 inverters in all motion axes to facilitate variable travel, lifting and lowering. This provides for gentler handling and greater precision in positioning thanks to smoother acceleration and braking motions as well as reduced oscillation during transport. Moreover, electrical braking reduces wear on the mechanical components, as speed adjustments are made pre-emptively. Proven over decades, the industrial drive solutions by Demag featuring ZBA motors and travel wheels ensure that the process cranes travel with exceptional smoothness that is gentle on the runways. Crane and travelling hoist positioning is continuously monitored by a long and cross-travel position measuring system, and data is transmitted to the bunker management system.

For retrieval, the crane picks the cocoa beans up with its large-volume grab and transports them to an output hopper. This is designed to prevent unnecessary dust. The cranes also utilise a multi-step opening method to raise less dust when they feed the hoppers. In addition, this method also ensures that the valuable and sensitive product is deposited very gently. The cocoa beans are transported to the loading points for trucks or barges via conveyor belts.

Transparent inventory management

This facilitates both on-time loading of the hoppers and transparent inventory management. Scanner systems were installed on the crane system to measure the height of the bulk goods. Scanners fitted below the crane bridge continuously track the height contours in each area of the bunker area. The software in the crane control centre uses the information to determine a precise height profile and visualises the fill levels in all storage areas, including the minimum and maximum amounts.

The stored fill level values prevent the grab from touching down hard on the bulk heap with a slack rope, further minimizing any damage to the husks when the stored product is handled and transported. In addition, the control centre shows the current status of the crane with all relevant status messages. Customer-specific storage strategies can be added via the user-friendly interface at any time.

Safe servicing

Each crane features a touch panel and a 7" display installed in the switchgear cabinet door. For system diagnostics, current operating and error messages are displayed in the order received, simplifying service work. Technicians can safely and conveniently carry out maintenance and any repair work from a walkway along the crane girder.

Special features

The integration of the three cranes into the existing bunker management system increases efficiency and transparency in managing the inventory. Demag realised crane communication with third-party programs for conveyors and output hoppers. The crane control and automation systems are optimised for operation with demanding and sensitive loads in a dusty environment at Vollers Holland B.V. and provide data on the system status, storage volume and operating processes in real time. At the request of the customer, the grab has attachment points for other loads as a special feature. At Vollers, this enables the crane to lift a mini excavator into individual storage compartments to sweep them clean once emptied.

The bottom line

A few months after commissioning the crane-operated terminal, impressions at Vollers are resoundingly positive. In the first nine months of operation alone, 80,000 tonnes of cocoa beans have been placed into storage. The automated material handling system with the three process cranes is reliable and ensures smooth material flow.