A smart approach to overcome air draught challenges: a case study

A cargo handling system shapes the operational landscape onboard a transshipper, writes Bagya Vivekanandhan, Technical Designer, ShiELD Services. At its core, it comprises key components such as hoppers, cranes and grabs, belt conveyor systems, as well as shiploaders, all working collectively for a synchronized material flow. During cargo transfer on board, there are multiple transfer points involved, the first one being the hoppers that receive cargo from the deck cranes. Therefore, it sets the course for a progressive and profitable cargo transfer rate.

The hopper design, including size, geometry, and accessories, mainly depends on the cargo characteristics, desired cargo transfer rate, and the available space on the transshipper. Depending also on the project requirements, a belt feeder is installed right below the hopper outlet to regulate the volume, distribution, and speed of the cargo being transferred onto the other conveyors. Moreover, additional flaps are installed around the hopper upper opening to contain potential cargo spillage during the discharge from the grab.

One of the consequences of this arrangement, i.e. installing the conveyor and hoppers on the vessel’s deck, is that the air draught of the transshipper is usually much higher than that of a traditional bulk carrier and this can result in limitations when the transshipper must load cargo from a standard jetty or loading facility.

Case Study

The project requires an existing Supramax bulk carrier converted into a transshipper with the installation of a complete cargo handling system including hoppers, deck cranes and grabs, belt conveyors, as well as shiploaders. During the development of the design, transshipment specialist

Shi.E.L.D. Services had to address an air draught issue which eventually involved a smart modification of the hopper features.

As per the loading plan, the transshipper is moored to the jetty on its starboard side where the hoppers are installed. The cargo is loaded directly at the port into the transshipper holds through a shore loading boom, which, considering its size and the operating parameters, determines the admissible air draught of the vessel to be loaded. This required a thorough study of the heights of the conveyor system during the design phase.

A preliminary study highlighted that, due to the high transshipper air draught, a potential interference between the hoppers and the shore loading boom had to be rectified to make sure that port loading operations could be carried out as planned. atmospheric factors such as wind and currents have a significant impact on water levels that cannot be overlooked.

For this purpose, Shi.E.L.D. Services investigated the following aspects to identify the ones on which we could intervene to find a possible solution.

Vessel draught: the v transshipper arrives at the jetty in ballast condition. In this project’s context, opting for a heavy ballast condition to reduce air draught was dismissed due to the time-consuming nature of filling/ emptying the ballast hold. The time required for ballast and deballast operations was a significant factor in this decision-making process.

Tide: the fluctuation of water levels v caused by tides inevitably affects the elevation of the transshipper (air draught) in respect to the height of the loading boom of the jetty. Additionally, in this specific location, local

Design of the cargo handling v equipment: since the transshipper is loaded dockside on its starboard side, which corresponds to the side where the hoppers are installed — among the tallest elements of the entire conveyor system — Shi.E.L.D.

Services had to focus on defining the precise height of the hoppers. This is to allow the shore-based shiploader to safely reach the cargo holds for the loading operations. It’s understood how crucial this aspect of the design is to avoid having excessively tall hoppers once the transshipper is in place for loading, as neither the hoppers nor the shore-based loader can be adjusted at that point.

Taking into account the operating needs and a cost-benefit analysis, Shi.E.L.D. Services evaluated the below listed possible solutions.

Of the four hoppers installed on the v starboard side of the vessel, the two central ones can be designed as movable type, allowing them to be shifted backward to create room for the loading boom. However, this would only be achievable with the installation of additional equipment resulting in higher costs and longer delivery time.

Lower the hoppers, but this would v also reduce the size of the hopper upper opening and reduce its volume. This would increase the risk of cargo spillage while feeding the hopper with the grab and increase the crane cycle, reducing the transshipper’s loading performance.

The anti-spillage plates, which v contribute to the hopper height, are usually fixed elements and most of the times just a simple extension of the hopper walls. Shi.E.L.D. Services decided to make the anti-spillage plates separate and independent from the hopper walls and make them foldable and actuated by an hydraulic system. The plates would be raised only during the offshore transshipment operations, whereas they would remain folded at port, when the cargo handling system is not in use. In this configuration the transshipper air draught was reduced enough for the shore loading boom to safely overcome the hoppers and to guarantee safe operations at port under any vessel loading conditions and with any tide.

Conclusion

Thanks to its holistic approach, Shi.E.L.D. Services was able to find a simple yet clever solution that helped overcome a strict limitation, which brought a great benefit to the project performance and the client’s success.

ABOUT SHI.E.L.D. SERVICES SRL

Shi.E.L.D. Services is a logistics management consulting services company that helps commodity traders, bulk shipping companies, port owners/operators, and other stakeholders in the dry bulk logistics sector. It enables companies to streamline their supply chain workflows, reduce operating costs, and maximize profitability. Shi.E.L.D. Services specializes in designing innovative and bespoke dry bulk logistics solutions and comprehensive technical consultancy that help unlock new opportunities.

Shi.E.L.D. Services’ expertise in logistics consulting services is deeply rooted in the dry bulk shipping sector. Its team of dry bulk shipping leaders and professionals has served in the core leadership at Coeclerici, one of the world’s leading industry players. It has, since then, built a reputation for excellence, reliability, and efficiency in the maritime logistics and shipping sectors.

As trusted partners in the operation of bulk carriers and transshippers, Shi.E.L.D. Services ensures the continuity of the logistics chain in challenging environments, providing critical first and last-mile connectivity with its fleet of custom-built transshipment vessels and feeder barges. Shi.E.L.D. Services has worked on several groundbreaking projects in Asia, Africa, and the Middle East, including the world’s first transshipment of granulated sulphur in the Black Sea.

Shi.E.L.D. Services is the consecutive winner in the ‘Bulk Logistics Excellence’ category at the IBJ awards 2019 and 2022, followed by the ‘Lifetime Achievement Award’ won by the CEO in 2023.

German company Loibl is a renowned expert in the bulk handling field, its product range includes: hopper cars and feed hoppers; material feed systems; shiploaders and unloaders; equipment for port handling in general; and more.

LOIBL BULK HANDLING HOPPERS

This article focuses on Loibl’s hopper expertise. Loibl is a reliable partner for all types of hopper cars. Whether mobile hoppers with their own drive, semi-mobile solutions coupled to another means of traction or stationary solutions, Loibl supplies customized hopper cars for every requirement. Its hopper cars are adapted to the bulk material, whether coarse or fine-grained, light or heavy. Loibl can adapt the size and geometry of our charging and feed hoppers to all requirements and supply appropriate discharge technology. Free-flowing bulk solids, dry bulk solids, and slightly moist bulk solids can all be handled by Loibl hoppers.

FEED HOPPERS & HOPPER CARS AT A GLANCE modular and partially bolted v construction; the design is created in 3D using the v latest drawing programmes; consideration and implementation of v all customer wishes and requirements; the components are manufactured in a v certified company using the latest production processes; and the load-bearing structures are v designed in accordance with the latest European regulations, taking into account the guidelines applicable at the installation site

INNOVATIVE SHIP-UNLOADING

Charging hoppers and hopper cars are usually required for ship-unloading of bulk goods using an excavator or crane. They act as a link between an unloading device or excavator and the subsequent transportation solution for the bulk material. Belt, chain or pan conveyors are used as discharge devices.

CUSTOMIZABLE

Hopper cars can be equipped with additional solutions, including filter systems and dust retention systems or special mechanical constructions and other equipment.

KEY FEATURES

Linings can be equipped with sliding v plastics. Water spraying devices enable safe v operation in explosive ambient conditions.

Feed hoppers and bins can be lined v with a wide variety of wear-resistant metallic materials.

Feed hoppers and bins can be v equipped with mechanical and/or pneumatic discharge aids.

Automatic water-wash systems for v cleaning the hopper surfaces during product changeovers.

Extraction and filter systems can be v integrated to ensure environmentally friendly, low-dust operation Platforms, maintenance walkways and v access points in the design are adapted to customer requirements and integrated into the design

CASE STUDY: INSTALLATION HOPPER CAR

AT PORT ODDA IN NORWAY — FEED

HOPPER FOR SMELTING PLANT

RETROFIT PROJECT IN NORWAY

Enclosed between mountains and fjords lies the zinc smelting plant for which Loibl Förderanlagen GmbH supplied a customized feed hopper system. The factory is being fundamentally modernized and extensively expanded.

In the process, the decades-old ship unloading system was replaced by a new one. The Loibl hopper car is an important part of the ship-unloading process. It is the link between the handling dredger and the conveyor system. The feed hopper leads right up to the factory and is equipped with modern and innovative solutions, including a dust retention system to enable dust-free ship-unloading.

BRIEF OVERVIEW

The hopper car runs on rails in the harbour and can be moved together with a transshipment dredger as needed. The dredger feeds the hopper with bulk materials that are needed for the zinc smelting plant and are delivered by ship.

The integrated extraction with filter system and special dust retention system in the bin prevents dust from developing in the surrounding area. Underneath the bin is a bin discharge conveyor, transporting material onto a stationary conveyor.

WEAR-RESISTANT CONSTRUCTION

A special plastic lining was selected for all surfaces in contact with material in order to improve wear resistance and gliding properties.

The dust retention system is likewise used in a reinforced version adapted to the customer’s needs. An integrated sprinkler system takes care of cleaning the bin.

DUST REDUCTION & WATER PROTECTION

The sophisticated extraction system of the feed hopper continuously extracts dustladen air. A rotary valve discharges the filtered dust onto a discharge belt and conveys it into the main material flow.

An additional special construction, the spillage board from Loibl, is used to collect spilled material during the transfer from ship to bin in order to guide it back into the ship. This protects the surrounding sea, so nature remains unaffected.

SCOPE OF SUPPLY AND SERVICES basic and detail engineering; v static design of the steel structure; v manufacturing in Straubing, Bavaria; v steel construction EXC3; v feed hopper and bin; v weighing system; v spillage board; v dust suppression system; v extraction with filter system; v LASHBELTCON® — belt conveyor; v electrical and control system; v assembly; and v commissioning. v

ENVIRONMENTAL RESPONSIBILITY AND SUSTAINABLE BUSINESS

Zinc is an essential raw material for numerous industries, which is usually delivered by ship. Investments in innovative conveyor and filter systems are crucial to protect people and nature and to maintain the economic viability of plants in the long term.

GAMBAROTTA GSCHWENDT Eco Hopper customized to meet user needs

GAMBAROTTA GSCHWENDT SRL was founded in 1919 by Umberto Gambarotta Senior in Trento after World War I and its main business was general mechanical work such as truck fixing, modifications transforming trucks from fixed to tipping, repairs to mining equipment, forge jobs, etc.

Steel parts were recovered from World War I remnants, since the region had been deeply affected by the conflict.

In 1958 Mr. Umberto Gambarotta Jr. (father of the current CEO, Mr. Davide Gambarotta) joined the family business and actively contributed to the real first corporate turning point: the truck repair business was replaced by the industrial activity of designing and supplying systems for cement plants, mines and magnesium.

GAMBAROTTA GSCHWENDT transformed itself from a mechanical repair shop, with exclusively local clientèle, to an entity dedicated to the design and supply of conveyor systems for process plants.

From the 1980s to the 1990s there was great international expansion of the company: from a European industrial reality (especially in Germany, ever since 1958),

GAMBAROTTA GSCHWENDT acquired a wide-ranging presence, by getting important foreign orders that led to the opening of commercial offices, first in the Americas, in Asia and then in Africa and Australia.

The new establishment of the Gambarotta Group, led by the current CEO, Davide Gambarotta, took place between 2019 and 2020 and is made up of five leading companies in the sector and about 130 people specialised in 44 different fields. The companies involved are:

GAMBAROTTA GSCHWENDT SRL, GAMBAROTTA AUSTRALIA, MDG HANDLING SOLUTIONS SRL, MDG AMERICA INC. and OSSITAGLIO SRL.

Our Mission is to offer customers our experience, knowledge and innovation to render the exceptional products that we design and produce available all over the world, thus creating value for all those who participate in the Company and share its objectives.

Davide Gambarotta – CEO, GAMBAROTTA GSCHWENDT SRL

Nowadays GAMBAROTTA GSCHWENDT’s main products include bucket elevators, screw conveyors, drag chain conveyors, pan conveyors, apron feeders, loading bellows, rotary valves, slide gates and top-quality spare parts for above mentioned equipment.

One of GAMBAROTTA GSCHWENDT latest products is the Eco Hopper, which can be considered the ultimate shipunloader evolution. Some of its features are detailed below.

The unloading process at the terminal is becoming greener than ever, since the GAMBAROTTA GSCHWENDT Eco Hopper can minimize dust pollution.

The loading capacity to the truck has been maximized, to a maximum of 1,500 tonnes per hour, thus meeting the needs of all its customers. Furthermore, the hopper storage capacity is 150m3

According to its application, the Eco Hopper can be designed with rubber tyres or rail bogies.

All GAMBAROTTA GSCHWENDT equipment, hence including Eco Hoppers, is completely customized according to the requirements of customers, and is designed, produced as well as erected by the company, following its high standards.

Should customers need it, GAMBAROTTA GSCHWENDT can provide commissioning and start-up on-site assistance as well as training for local staff.