Cargotec offers custom-designed MacGREGOR
self-unloaders to maximize cargo flow efficiency
A second MacGREGOR self-unloading system from Cargotec for
the Gypsum Transportation company is now fully operational
and offers a discharge capacity of 3,000tph (tonnes per hour),
uninterrupted gravity flow of material from its cargo holds, and
increased cargo hold volume
Following the successful introduction in 2001 of Gypsum
Transportation Ltd’s 39,000dwt self-unloading bulk carrier
Gypsum Centennial, in July last year a second ship, the 47,800dwt
Gypsum Integrity, was delivered to the same owner, a subsidiary
of United States Gypsum Company,
Both ships feature a similar custom-designed self-unloading
conveyor system from Cargotec Sweden AB and have a
discharge rate that is variable to a maximum of 3,000tph or
2,500m3 per hour.
Gypsum Transportation has operated self-unloading vessels
for decades. In 1999, it decided to upgrade its fleet and ordered
a new self-unloading vessel, Gypsum Centennial, from Hyundai
Mipo Dockyard in South Korea. In 2006, the owner decided to
order a second vessel, and Gypsum Integrity was built at a
Brazilian shipyard, Estaleiro Ilha SA (EISA) in Rio de Janeiro, and
delivered to the owner last year.
Since its delivery, Gypsum Centennial has been mainly
operating along the US East Coast carrying gypsum rock but
also coal and other coarse materials. It has now been joined by
sistership Gypsum Integrity. “The new vessel made its first
discharge, with gypsum, in Jacksonville in Florida last year,” says
Björn Berglind, product manager in Cargotec. “At the same time
the commissioning of the self-unloading system was carried out
to the owner’s satisfaction.”
 
THE SELF-UNLOADING SYSTEM
Cargotec is a leading worldwide supplier of shipboard
MacGREGOR dry bulk discharging systems which have
established an excellent reputation since the first was supplied
over 60 years ago. It offered totally enclosed and dust-free
solutions for a great variety of commodities and with some of
the highest capacities on the market.
Gypsum Centennial and Gypsum Integrity each has four cargo
holds that are loaded through eight hatch covers. The holds
have sloping bases, providing a gravity flow for material down to
two parallel longitudinal slots in the bottom. Attached to each
of the longitudinal slots are nine moving hole feeders, which have
been supplied by Kamengo Technology Inc. in Canada.
These units feed the material at a constant rate to two hold
conveyors, which incline in the aft part of the cargo hold area
and discharge the material onto the cross conveyors. From the
cross conveyors, the material is transferred to a C-conveyor
located on the ship’s centreline, just in front of the engine room
bulkhead.
The C-conveyor elevates the material to main deck and
discharges it onto a slewable and hoistable boom conveyor.
“The telescoping boom is designed for easy positioning and
transferring of the material to the receiving arrangement
ashore,” Berglind explains.
To meet the latest IMO regulations for maximum security
and water integrity during a voyage, the vessels are also fitted
with MacGREGOR watertight bulkhead doors from Cargotec.
These have been installed where each hold conveyor penetrates a
bulkhead.
A hydraulic power pack is installed in a separate room and
powers the moving hole feeders, boom conveyor and watertight
bulkhead doors.
Electrical switch gear and a PC unit have been installed in the ship’s
central electrical room. The operation and control of the entire
conveyor system is undertaken from a terminal located in a separate
control room in the ship’s accommodation. The entire
unloading operation can be supervised from a local PC terminal
in the ship. The extensive alarm
system gives instant information of all
components, conveyors and units of
the self-unloading system in case of
malfunction.
 
MOVING HOLE FEEDER
Compared to conventional gates, the main feature of the
hydraulically-operated moving hole feeder is the elimination of
‘hogbacks’– which are protective covering structures for
supports that are traditionally used in the bottom of cargo holds
between the gates. This creates and maintains one continuous
slot for the entire length of the cargo hold. The absence of
hogbacks, in combination with the moving hole feeder design,
creates an uninterrupted gravity flow of the material from the
cargo holds and increases cargo hold volume.
The feeder mainly consists of a moving deck with openings to
the cargo holds (moving holes) and a number
of trays placed under the openings. A
stationary ladder is located between the deck
and trays. As the deck and trays traverse back
and forth, the ladder rungs act as a scraper and
feed out the material to the belt conveyor
underneath. The ladder rungs also function as a
seal to avoid overflow of material from the
cargo holds.
Due to its ability to accommodate variable
speeds, the ship’s discharge capacity can be
selected to match the shore receiving facilities
and the material handled.
Apart from free-flowing bulk materials like
gypsum rock, coal, gravel, grain and iron ore,
more difficult commodities, like synthetic
gypsum, can also be handled.
 
BOOM CONVEYOR
“Cargotec’s telescopic boom design for this application has a
travelling length of 36m, which is exceptional considering that
the maximum boom length is 76m and the minimum length in
retracted position is only 40m,” highlights Berglind. “Thanks to
the shuttling conveyor, it is easy to position the boom conveyor
in order to distribute the material directly to stockpiles onshore
or to transfer to other receiving arrangements, such as hoppers
and conveying systems.” A travelling telescopic discharge chute
is attached to the discharge end of the shuttle conveyor to
reduce dust and avoid spillage during transfer to shore receiving
facilities.
 
BOOM SLEWING ACTUATOR
The hydraulic slewing actuator and its integrated hydraulic
power pack have been specially-designed by Cargotec to ensure
the required high torque and maximum slewing angle. “They
also provide a smooth and even slewing action, which is essential
when positioning the boom conveyor during the discharge
operation,” he notes. “In addition, the compact design requires
only a limited space between the boom structure and ship’s
deck.”
 
 
Mentor Dynamics Ltd – pioneers in the use of polymer as hold liners
In the early 1970s, Mentor Dynamics Ltd. pioneered the use of
polymers as liners for the cargo holds of self-unloaders. Today,
the company’s liners are used worldwide in self-unloading vessels
and barges where material flow is essential to maintaining high
discharge rates and productivity.
The use of the company’s liners began in an initial test
application on a CSL (Canada Steamship Lines) self-unloader
prior to the start of a contract for the carriage of western
Canadian coal. At that time, western coal was known as a
problem cargo for gravity discharge self-unloaders. Unloading
operations often took as long as two days due to poor material
flow. Following successful installation of the company’s liner, the
average discharge time was reduced to just eight hours.
Since the success of the initial application, the use of the
company’s liners has become recognized as a cost-effective way
for self-unloading vessels to solve the flow problems associated
with sticky or cohesive cargoes. The company’s initial liner
design and patented fastener system provided the basis for the
successful early results, but has been improved with innovations
in critical design elements and in the introduction of second and
third generation fastener technology. The company markets its
Dyna-Flo® brand liners worldwide to the marine market, and is
the leading supplier of these specialized marine products.
 
CURRENT ACTIVITY
As the presence of self-unloaders spread from the Great Lakes
to their current use in many parts of the world, Mentor
Dynamics followed shipbuilding to shipyards in Asia, Europe,
South America and other countries. Most recently, Mentor has
partnered with a number of Chinese shipyards, including
Chengxi Shipyard Company, Ltd. to provide ship owners with a
well-designed and properly installed liner. In 2008, the company
designed and supplied liners for Seaway Marine Transport’s
(SMT) two forebody conversion projects. These Caribbean
Class vessels were slated for completion at the Chengxi yard in
Jiangsu province in 2009. The conversion of the first vessel, the
Algobay, was completed as scheduled. Unfortunately, the loss of
the Algoport, as she was being towed to the yard has delayed the
second project. Prior to the SMT projects, the company worked
with Chengxi and Shanhaiguan Shipyards to provide liners for
Panamax class vessels for Algoma and CSL International’s
conversion projects on the Henry R. Jackman, Arcadian, Argosy,
Baldock, and Metis among others.
For new construction, the use of a Dyna-Flo liner allowed
ship designers to decrease the traditional hopper slope angles to
angles as low as 35°. This modification increases cargo capacity
for a given area and increases vessel stability. Without the aid of
a low-coefficient-of-friction cargo hold liner, these slope angle
modifications would have created insurmountable flow problems.
Mentor custom designs each liner to the customer’s exact
equipment needs. The company uses a computer-aided design
(CAD) system to prepare the required liner design and
fabrication specifications. In many cases, the company relies on a
proprietary data base of hundreds of equipment specifications to
facilitate the design. After the design is completed, the data is
transferred to the computer controlled cutting equipment that
fabricates the liner. The Dyna Flo liner material is made by
advanced, state-of-the-art, polymer technology. The physical
properties of the liner include excellent toughness, abrasion
resistance and a low coefficient of friction, properties that are
ideally suited for the needs of marine applications.
 
REPORTS FROM SHIP OWNERS
Ship owners have reported and documented both economic and
safety advantages:
  reduced unloading and clean-up time;
  little or no residual cargo;
  no need to send men into cargo holds; and
  reduced liability.
 
A CASE HISTORY
A Canadian ship carrying coal had nearly 30% of its cargo space
displaced by hardened coal. The shipping company tried a range
of conventional approaches and even considered the use of
explosives to break the hardened coal. After installing a Mentor
Dyna Flo liner, the ship operated at its designed carrying
capacity, an increase of 12,000 tonnes per trip. The enhanced
productivity provided a rapid financial payback.
Mentor Dynamics remains dedicated to the marine cargo
liner business and works co-operatively with shipyards and ship
owners to optimize the performance and value of the installed
liner. The company has also partnered with major material and
component suppliers with facilities around the world to maintain
a supply chain that allows the company to offer its products and
services at cost effective prices in world markets.
 
OTHER PRODUCTS AND SERVICES
The company also designs, fabricates, and installs polymer and
ceramic liners for industrial applications such as chutes, hoppers,
and material handling equipment. Major applications include coal
fired electric power plants, gypsum plants and other bulk
materials facilities.
The company describes itself as a ‘Specialist in facilitating the
flow of bulk solids’ and that really describes its approach with
customers as it works to solving their material handling
problems.
 
 
EMS-Tech gravity self-unloaders — an update
Since the dawn of humanity, man, community and industry have
located adjacent to navigable waterway systems. This is no more
apparent than on the Great Lakes of North America. The Great
Lakes St Lawrence Seaway System allows ships to travel some
3,750km from the East Coast of North America into the
heartland of both Canada and the USA. Water was the
dominant form of inland transportation in most parts of the
world through to the 20th century and, to this day, it remains
the most efficient form of transportation for bulk material
products.
With readily available access to water, the Great Lakes
became an attraction to industry, commerce and people. Local
quarries and salt mines were quickly located within easy access
to the water and the iron ore required to fuel the growing steel
industry started flowing into the Great Lakes region, first from
the Marquette Range and later from the larger Mesabi Iron Ore
Range. Within time it grew to include coal from the Powder
River Basin located in Montana/Wyoming, and grain from the US
Midwest and the Canadian prairies.
The true catalyst for self-unloaders was the number of short
haul trade routes that inherently exist within the Great Lakes
system. Trade flourished and grew exponentially with the
construction of the Welland Canal, the Soo Lock system, and
eventually the St. Lawrence Seaway system in 1959, which
allowed ship transit between Lake Superior, Lake Ontario, and
ultimately the Atlantic Ocean, overcoming a height difference of
some 180m. While expensive and massive machines for
unloading vessels did appear, these were generally restricted to
those located at the very largest of ports.
With trade and commerce on the Great Lakes flourishing, at
least one enterprising individual by the name of Frank Merrill
concluded that technology commonly employed in quarries,
could be made to work on ships. This, he was convinced, would
ultimately result in faster discharges, more trips, and more
product delivered. And so it was in 1902 that the first selfunloader,
the Hennepin, made its debut on the Great Lakes of
North America. The Hennepin (see photo above) formerly the
George H. Dyer, was launched in 1888 and converted to a selfunloader
in 1902 by its owner, the Lakeshore Stone Company.
As the company name suggests, the ship carried mainly
limestone between its quarry located in Stone Haven and the
Illinois Steel Plant located in Milwaukee, some 50km to the
south on Lake Michigan. Interestingly enough it carried a
backhaul of coal to fuel the steam plant located at the company’s
Stone Haven quarry. It goes without saying that much has
happened in regards to the gravity self-unloader since that time.
While today’s gravity self-unloaders (see picture of the
Bulknes on p73) embody the same framework as their ancestors,
namely hoppered cargo holds, discharge gates, tunnel conveyors,
elevator and discharge boom, suffice to say that that is where
the similarity ends.
Not only do they deliver a greater volume and variety of materials, they do
so in a more efficient and in an environmentally conscious manner.
Hand-operated small discharge gates (right), suitable for
only free-flowing materials, have been replaced with hydraulically
operated large discharge gates which are suitable for a variety of
free flowing and poor flowing cargoes. Gone are the days of
putting men into cramped tunnel space to operate the discharge
gates. Today’s self-unloaders can be discharged with ease by one
crew member from a control console (see below) located in
clean space in the accommodation block.
While there are obviously a great number of elements that
combine to make today’s gravity self-unloader efficient, such as
flow aid devices, cargo hold linings, efficient elevating systems,
reliable control systems and dust control systems, by far the
most significant feature is the gate system. The gate system is
tasked with the reliable transfer of material from the ship’s cargo
holds to the tunnel conveyor belts located below them, while
maximizing cargo hold cubic. The EMS-Tech patented Feeder
Gate (see below) is a stand-out in this regard.
The EMS-Tech Feeder Gate system allows the ship to deliver
material at consistent rates into receiving hoppers or stockpiles
located on shore. Its success can be attributed to its simple
form, the drop action that takes place upon initial opening,
synchronized opening over the centreline of the receiving
conveyor, and the fact that it can be used below hopper
openings measuring 3m wide x 3m long, with receiving belts of
width equal to, or greater than, 2,200mm wide. The size of the
opening, combined with gate action, make it ideal for poor
flowing material such as ore concentrates and synthetic gypsum.
Now employed on 15 self-unloaders, the EMS-Tech Feeder Gate
system brings together the use of tried and proven basket gate
technology and accurate and reliable feedback systems.
Automation is a term that is often used incorrectly within the
industry to describe remotely controlled conveyor and gate
systems, features which are commonplace on today’s gravity selfunloaders.
These typically comprise industrial remote I/O
stations, main PLC, server computer and client computer for
communicating with the operator, all of which combine to allow
for discharge of the vessel by one operator positioned at a
console located in a control room. Additional client computers
can be added as desired to allow communication, control, or
monitoring, as appropriate, from the engine room, bridge or
Chief Engineer’s quarters. Remote I/O boxes serve to greatly
reduce the number of power cables and communication cables
that run through the tunnels. One two-conductor cable for
power and one two-conductor shielded communication cable
control all of the gates over one tunnel conveyor. Before the
introduction of remote I/O boxes, thousands of cables would
have been involved to remotely control and power this same
string of gates. This has been a tremendous advancement.
Coupled to this has been the increased reliability of these
devices at a greatly reduced cost.
Gravity self-unloaders excel as a result of their ability to
discharge material at a high rate of speed. It is not surprising,
therefore, that many of those in place on the Great Lakes of
North America can discharge at rates of 6,000tph (tonnes per
hour) or more. While fewer in number, the so-called ‘1,000
footers’ (see photo of Paul R Tregurtha on p71) incorporate
unloading systems capable of discharging at a rate of 10,000tph.
Gravity self-unloaders, while recognized as the top performer
in this field, are but a small portion of a broader field which
includes top reclaim systems. Top reclaiming self-unloaders
include traditional geared bulkers fitted with pedestal cranes,
bulkers fitted with gantry mounted cranes, geared bulkers fitted
with deck conveyors and discharge boom, bulkers fitted with
deck mounted reclaimers, top down reclaiming systems and
pneumatic systems. While each of these surely fulfills a role,
none can outperform the gravity self-unloader when it comes to
overall efficiency, cleanliness and performance. As noted by a
good friend in the business several years ago, ‘gravity is free’; it
makes good sense to use it.
 
CREDITS
Information regarding the Hennepin has been drawn from the
William Lafferty/Valerie van Heest book entitled Buckets and
Belts – Evolution of the Great Lakes Self-Unloader, published by In
Depth Editions, 2009
 
By John B. Elder, P.Eng., EMS-Tech Inc., VP Marketing, Sales &
Product Development
 
SMT’s New Caribbean-class ‘Algobay’ returns to active duty
The original Algobay was built as Hull 213
at Collingwood, Ontario. It was launched
on 19 June 1978, and entered service on
20 October 1978.
At 222.51 metres in overall length and
23.22 metres at the beam, this was the
widest ship to that date built at the
famous Georgian Bay shipyard.
Algobay had special features including a ‘shaped’ bow to the
24 foot line for work in ice which represented a design
departure from the traditional ‘laker’. The cargo holds had a
polyethylene lining for a smoother flow of cargo.
The 22,466 gross tonne self-unloader was powered by two
Crosley-Pielstick diesel engines and the ship could carry up to
34,200 tonnes deadweight at salt water draught.
Algobay went to work on the Great Lakes, down the St.
Lawrence and around the Eastern Seaboard of Canada carrying a
variety of cargoes for company customers.
These included iron ore, grain, coal and stone. The ship also
loaded 33,000 tonnes of salt at Saint John, NB in May 1983 and
this was the first shipment in a six year contract to deliver that
commodity to Montreal.
During the winter of 1988, Algobay was at Port Weller Dry
Docks for work to ‘stiffen’ the hull and enable the ship to be
re-classed as ‘Caribbean-class’ for extended trades on the East
Coast. While in the south during the summer of 1989, the alert
crew rescued two sailors in trouble in a small sailboat in the
Florida Straits.
Beginning in February 1990, Algobay spent most of its time
on salt water. The engine was modified to burn a more
economical residual fuel during a stop at Jacksonville, Florida in
April 1991.
After returning to the Great Lakes late in 1993, the ship tied
up at Port Colborne, and was chartered to Canada Steamship
Lines and renamed the Atlantic Trader in
1994. The vessel again combined Great
Lakes and coastal service and
occasionally loaded at Ashtabula, OH as
part of a large contract of Appalachian
coal delivery to Belledune, New
Brunswick.
Algobay had a few mishaps over the
years. These included a collision with a tug and an Italian
freighter off Sept Isles on 14 November 1978, another in heavy
fog with the bulk carrier Montrealais in the St. Clair River on
25 June 1980, and a grounding at Crossover Shoal near
Brockville on December 1, 1979.
Algobay tied up at Toronto in December 2002 and remained
idle until a decision was made by joint owners Algoma Central
Corporation and Upper Lakes Shipping to rebuild the vessel.
It was towed to Hamilton on November 28, 2007, and left
there under tow on May 13, 2008, for Montreal. The deep sea
tug Hellas took up the tow on 25 May and handed the hull over
to the Simoon at Gibraltar on 16 June.
After going through the Suez Canal in early July, Algobay
arrived at the Chengxi Shipyard at Jiangyin, China, on
10 September 2008.
The new Algobay will only utilize the stern shell of the
original ship. The original forebody was cut off for scrapping and
a new forebody was launched on 30 March 2009, and later
joined the existing stern to form the new Algobay.
The ship has new engines, mechanical and navigation
equipment and self-unloading gear.
After consultation with third party experts, it was decided
that the safest routing for delivery, would be to cross the Pacific
Ocean just north of the equator, transit the Panama Canal, then
proceed north along the Eastern seaboard of North America.
The vessel arrived in Portland Maine on December 29th.
 
 
De Regt Conveyor Systems – mobile conveyor systems
De Regt Conveyor Systems from the Netherlands develops and manufactures mobile conveyor systems and also conveyors to unload vessels and ships.
The capacity of the system can easily go up to 2,000tph (tonnes per hour), but most of the time depends on what a client wants and how fast he wants to unload his vessel. It is used mainly for sand, gravel and stones.
The conveyor system to unload the vessel is made of belt conveyors and a hopper which are mounted on a mobile rail system together with a crane. The avantage of the selfunloading vessel is its independence.
The vessel can also supply clients without the need to hire a mobile crane or other equipment. De Regt Conveyor Systems has already made such conveyors for S.E.A.M. Oosterlee bv of Breskens and for Versloot in Sas van Gent.
The first one for S.E.A.M. Oosterlee consists of three conveyors. The system is used to overload the products to a smaller vessel or to unload directly on the quay. The first one in the length of the vessel with a mobile frame above it (with the crane and the hopper on it) which can be put on rails on both sides of the vessel. This conveyor has a length of about 40m and is 1,200mm wide.
The second one is the one that feeds the last one and it is perpendicular on the first one. This one has a length of 9m and the same width. The third one is the one that can make a turn of about 180°, is adjustable in height and is used to unload the different types of product on the quay. This one has a length of about 35m. The capacity of the system is about 1,500tph (1.8 tonnes per m³). The second one for Versloot in Sas van Gent consists of one conveyor and one hopper and crane. The belt has a length of 38m and a width of 800mm. The capacity is about 800tph.