Ship unloader

01

Match the unloading principle to the cargo

Siwertell, a screw-type unloader maker, describes its C-type as a high-capacity continuous screw unloader mainly used for non-free-flowing, compact commodities that need high digging capability, with a winch-luffed horizontal arm and fixed counterweight, and says the C-type "is often used for off shore and narrow quay applications in terminals with high annual throughput". Its product table separates models for free-flowing cargo (cement, alumina, ground slag, dry fly ash, grain, animal feed) from models for various cargo including coal, fertilizers, minerals and chemicals. [1]

Bühler, a maker of mechanical (chain) unloaders, argues in a 2019 IAOM presentation that tightening rules on dust emission, spillage and noise, and food-safety separation of grain terminals, are moving grain terminals away from grab unloaders; it describes its Portalink unloader leg on a spherical suspension and an auto-sink feature that compensate for vessel movement, slewing and luffing with kick-in and kick-out to reach under the hatch rim, and a slow-moving product column for gentle handling and low energy per tonne. It notes that vertical suspended unloaders cannot reach under the hatch rim and that the working range affects clean-up time. [2]

Editorial note: the sources are makers arguing for their own principles; ask each supplier for energy per tonne, clean-up method and achieved average rates on comparable cargo and vessels.

Give the supplier the commodities and their flow properties, bulk density and temperature, annual tonnage and required capacity, vessel sizes (DWT, hatch sizes, hold depth, air draft at all tides), berth type (quay, jetty, offshore) and loads, onward conveying, dust, spillage and noise limits, food-safety requirements, power supply and clean-up arrangements.

02

Size capacity, vessel range and boom

Siwertell's table gives capacity ranges by model: 100–300 t/h for 5,000 to 15,000 dwt ships on free-flowing cargo (5,000 S and 10,000 S), 200–550 t/h for 15,000 S units, 200–800 t/h for Panamax F and G types, 500–2,500 t/h for C- and D-types serving ships up to 180,000 and 200,000 dwt, 600–1,600 t/h for the Cape-size M-type, and 200–550 t/h for its grain PortMaster up to 120,000 dwt, mounted on rails, tyres, fixed or offshore. It states that capacity depends on material, ship size and other factors. [1]

Bühler's range runs from the Portalino 300 (300 t/h, 20 m boom, 3,000–30,000 DWT) and Portalink 400 (400 t/h, 25 m, up to 60,000 DWT) to Portalink 600–1,300 (600–1,300 t/h, 25–32 m booms, 10,000–120,000 DWT). [2]

Editorial calculation: a 60,000 t grain cargo at a nominal 1,100 t/h takes about 60,000 / 1,100 ≈ 55 hours of unloading, and at 2,500 t/h about 24 hours, before hatch changes and clean-up, which reduce the average rate. Cargo size is an assumed example; ask for the average rate over a full vessel, not only the peak.

03

Check what a pneumatic unloader's rating is based on

German maker NEUERO describes its pneumatic ship unloaders as custom-built to site conditions, from power supply to boom length, and states capacities on wheat: up to 1,000 t/h per conveying line and up to 2,000 t/h on a rail-mounted tower with two separate conveying lines. Machines can be stationary, rail-mounted or on a rubber-tyred chassis, fed by low or medium voltage or by diesel generator, with an ATEX explosion-protection concept where required. [4]

Editorial calculation: at 1,000 t/h, discharging 60,000 t of wheat takes 60 h of net pumping, or 30 h with two 1,000 t/h lines; the rating is stated for wheat, so ask for the capacity on your own cargo and the clean-up method for the last part of each hold (NEUERO's 15 t auxiliary winch exists for that purpose). [4]

Compare that basis with Siwertell's statement that its screw unloader capacity depends on material, ship size and other factors, and write the cargo, bulk density, ship size and the clean-up share into the tender. [4] [1]

04

Compare what suppliers offer

Suppliers linked to this page list ship unloaders; each card links to the page reviewed.

Listings include pneumatic ship unloaders, mobile ship unloaders, grab-type and screw-type ship unloaders from a port-crane maker, ship unloaders from crane and trading companies, and ship unloader fabrication by an engineering firm. Ask each for principle, capacity on your cargo, vessel range, reach and environmental controls.

05

Write wind, duty, noise and acceptance limits into the tender

Port of Koper's 2018 technical specification for a 32 t grab-type ship unloader shows the limits a terminal can write into a tender. It asks for three-shift work (3 x 8 hour) at ambient -12 to +45°C, full operation in wind of 0 to 22 m/s, limited performance from 22 to 35 m/s, wheels in parking position from 35 to 44 m/s and stowed condition above 44 m/s. It sets a 32-tonne rated grab load, calculated to exceed hoisting capacity by 20% before overload protection acts, a maximum digging capacity of 2,000 tonnes/hour, a free digging capacity of 1,500 tonnes/hour and vessels up to 200,000 DWT, with design to F.E.M. 1.001 3rd edition, structure group A8 and hoisting and closing mechanisms classed T8 – L4 – M8. [3]

The same document caps noise at 70 dBA inside the operator cabin and 72 dBA inside the electric control room, and specifies a 105 m³ hopper holding up to 110 tonnes in normal operation with high-pressure water-fog dust suppression of at least 100 bar and 2 pumps. Its design cargoes are coal at 0,8 tonnes/m3 with lumps up to 50 mm and iron ore up to 2,5 tonnes/m3 with lumps up to 250 mm, and it asks for an anticorrosion coating of at least 250 μm dry film. [3]

For warranty and handover it asks for at least 2 years on mechanical and electrical components, 5 years on the steel structure and 10 years on anticorrosion protection, spare parts for at least 10 years, delivery fully erected, testing and acceptance within 1 month, and 15 working days of maintenance and operator training after acceptance. [3] Editorial note: this is one terminal's grab unloader for coal and ores; use its structure as a checklist and put in your own cargo, berth and climate values.

06

Trace the unloader components

This is a functional reference built from the sources cited; it is not one maker's specification.

07

Fill the specification fields with values for your terminal

A ship unloader quotation needs values for your terminal. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

08

Send the cargo, vessel and terminal data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Cargo: [commodities; density; flow properties]
Volume: [annual tonnes; required rate]
Vessels: [DWT range; hatches; air draft]
Berth: [quay, jetty or offshore; loads]
Type: [screw; chain; pneumatic; grab]
Environment: [dust; spillage; noise; food safety]
Power: [supply; energy limits]

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