SHIP LOADER CONVEYOR UPGRADE POSITIONS PORT OF SEWARD FOR GROWTH IN COAL HANDLING

Located on the Alaska's scenic Resurrection Bay, the ship loader at the Port of Seward loads coal for export.	To improve flow and reduce the escape of dust and spillage, Aurora Energy Services authorized improvements to the ship loader’s boom conveyor.

[Seward, AK] -- The Port of Seward has completed a conveyor system upgrade for its coal handling operations that has raised throughput by an estimated 20%, allowing Alaska’s largest coal producer to better compete for international customers.  By installing the new EVO® Conveyor Load Zone from Martin Engineering, the terminal has increased the average load rate for the entire ship loading process from 700 mt/h to 858 mt/h, while dramatically enhancing control over dust and fugitive particle emissions. 

With throughput increased, ship loading times are being reduced, driving down costs and making the exported coal more affordable to overseas buyers.  “Basically, we should be able to knock one day off our loading time for each ship,” observed Steve Denton, VP of Business Development for Usibelli Coal Mines. 

The terminal has progressed from an absolute maximum of 18,000 mt/d with dry coal and optimal loading conditions to more than 20,000 mt/d on average -- including operations in poor weather and less than ideal operating conditions.  “Over the course of a million tons per year, that’s a major savings for our customers, as they’ll be able to enjoy better FOB prices.  We also save on the cost of ship demurrage, which helps pay for the cost of the conveyor investment,” Denton said.

Port a Critical Link
Since 1985, the Port of Seward has shipped over 16 million mt of coal, all of it originating at the Usibelli Coal Mine 400 miles to the north, which currently exports more than 45% of its annual production.  UCM and its affiliate Aurora Energy Services, LLC (operator of the Seward coal terminal) have no doubt that the port plays a key role in their future.  With one of Alaska’s few year-round ice-free harbors, Seward has the ship-loading resources to feed the expanding international export market.  It’s also the southern terminus of the state-owned Alaska Railroad, with terminal facilities owned by the railroad and operated by AES.

A major obstacle to expansion was the port facility’s aging infrastructure, which had seen few improvements prior to 1999.  Upgrades began that year when Alaska Railroad purchased the terminal, but despite best efforts, by 2008 the facility had become a logistical bottleneck and a source of occasional dust complaints.

One of the issues was the ship loader itself.  With a view to expanding Usibelli’s export market share, AES began taking steps to increase throughput at the Port facility, but initial efforts to reach 2,000 mt/h proved almost entirely unsuccessful.  “Working with what we had, we could only reach 600-700 mt/h,” said AES Terminal General Foreman Vic Stoltz.  “We made some improvements and got up to a steady run rate of 750 mt/h.  But there were still some major issues with coal backing up in the chute.”

Even as some gains were realized, AES found that with higher-speed operation, dust became an increasing problem.  The ship loader wasn’t designed to contain fugitive material, and airborne coal dust generated negative attention, threatening community relations.  The company reports that the recent chute upgrades have virtually eliminated spillage and dust issues.

Combining Solutions
The need to increase throughput at Seward while protecting the region’s air quality and natural splendor led AES to investigate new conveyor technology from Martin Engineering.  After testing the Usibelli coal to determine its flow properties, Martin specialists used Discrete Element Method modeling to design a chute capable of properly handling the coal. 

“When we got back the computer models, we saw that we were able to pass 1500 mt/h and still control dust, all while keeping within our capital budget,” said Stoltz.  “When our management realized that we could increase throughput, increase safety and reduce our environmental impact all at once, they were completely in favor of implementing the suggested upgrades,” he recalled.

A New Conveyor Architecture
The new transfer point makes use of MARTIN® INERTIAL FLOW™ Transfer Technology, the entire chute custom-engineered and modeled in 3-D to provide the optimum design for the material and flow rate needed.  The “hood” controls the flow of material from the discharging conveyor, maintaining a coherent material stream and minimizing induced air.  A smooth loading chute (“spoon”) places the stream of coal onto the ship loader’s boom conveyor at the proper speed and angle with minimal impact, reducing material degradation, belt abrasion and the expulsion of airborne dust. 

Martin Engineering supplied other redesigned components to contain material and improve serviceability.  Belt support cradles were installed under the drop chute to absorb impact and stabilize the belt line and prevent spillage.  AES also mounted EVO® External Wearliner on the load zone’s existing skirtboard for improved sealing.  Because it is attached from the outside, it is easier to install, inspect and adjust than conventional seals, without requiring confined space entry.

Results
The first thing the AES crew noticed was an improved material load rate.  During the initial shakedown run, operators noted the conveyor’s weigh scale pegged at 100%, but the belt didn’t shut down.  The old system peaked at 1000 mt/h (including ship and hatch moves), but with new components in place, the system now hits peaks of 1500 mt/h.  “We don’t have slowdowns due to the chute clogging up, which previously was a constant battle,” Stoltz added.

Equally important, following the system’s initial run, the ship loading area was virtually free of fugitive material and dust build-up, allowing AES crews to reduce their cleanup time from days to just hours.  “The clean-up time has been reduced by more than 40 man-hours per shipload,” said Stoltz.

Reducing Risk
To AES, the environmental and worker safety benefits of Martin Engineering’s upgrades have been just as important as the production advantages.  “Faster loading times help manage our risk, from both the environmental and safety perspectives,” commented Bart Coiley, AES Manager of Environmental Affairs.  “The longer it takes to load a ship, the greater the chances of creating dust.”

Summarizing the experience, Denton said, “The work that Martin Engineering did eliminated a chronic bottleneck for us.  There were many things we were doing to increase our throughput, but it was impossible to realize the full benefits until we cleaned up our loading operation with the installation of the new EVO® hood and spoon transfer chute.”  Stoltz added: “With these upgrades, we’re earning our money back every time we start it up.”

With the new conveyor Load Zone from Martin Engineering, the terminal has increased the
average load rate for the entire ship-loading process from 700 mt/h to 858 mt/h.

With its slide-in/slide-out cradles and external wear liner,
the EVO® Conveyor Architecture simplifies maintenance.

BIOMASS-FIRED POWER PLANT CONTROLS DUST WITH LIGHTWEIGHT, AIR-SUPPORTED CONVEYOR

Air-supported conveyor system eliminates idlers. 

[Emden, Germany] -- A biomass-powered 20 MW generating station has specified a totally-enclosed, air-supported conveyor system to feed its new woodchip-fired block, achieving exceptional control of fugitive materials in the strong winds common to its North Sea location.  Owned by BKE (E.On Kraftwerke 70% and STATKRAFT Markets GmbH 30%) and managed by STATKRAFT Markets GmbH Kraftwerksgruppe Nord-West, the facility’s new conveyor installation has proven so successful that it has been able to comply with strict dust control specifications and prevent nuisance dust from accumulating on new automobiles in nearby transit lots.

At the outset, company officials knew they needed a conveyor with a relatively long span to transport bulk material 167 meters (548 feet) from the ship unloading facility to two storage silos.  In addition, because of the proximity to the sea, corrosion protection was essential to the conveyor system’s durability.  Complicating the engineering task was a limited amount of available space for the conveyor’s support structure.  The system would be expected to operate for extended periods with very little maintenance, preventing the escape or buildup of fugitive material and also protecting the load from rain that would introduce unwanted moisture to the fuel.

Specifying the Right System
After reviewing several options, the company specified a lightweight conveyor design with a history of delivering excellent dust control from Martin Engineering.  The Air-Supported Conveyor is a simple and economical system that resolves many of the issues encountered with conventional belt conveyors. 

“Air-supported conveyors eliminate the carrying-side idlers used on conventional designs,” explained Werner Baxmann. “Instead, they employ a film of air rising from a troughed pan to lift the belt.  By removing a source of friction and the need for periodic maintenance, air-supported designs can offer significant advantages, including energy, environmental and safety benefits,” he said.  This thin air film can properly support loads and deliver high speed operation, while generating virtually no mechanical friction.  As a result, a drastic reduction in operating and maintenance costs can be achieved.

To accommodate space limitations at the Emden facility, the conveyor structure was engineered with an innovative triangular framework.  Constructed of galvanized steel to withstand the coastal climate, the high-strength modular design was able to span the entire distance with just two intermediate supports.  The conveyor is 40 inches (~1 meter) wide and travels up a constant 10° incline for a total elevation of 29.5 meters (97 feet) over its total span.

Designed for a Smooth Ride
The concept of the air-supported design is fairly simple, with the load zone and carrying sections contained in a plenum, which is pressurized by a centrifugal fan.  Holes in the top of the plenum create an air film between the plenum and belt, which supports the moving load.  By starting
with the weight of the belt and the load at the Emden plant, system designers could estimate the pressure needed to deliver about 1 mm of lift, which requires minimal air volume in most applications.

The conveyor needs no compressor, able to power up to 600 feet (183 meters) of belt supported by a single low-power fan.  Extremely low friction inherent to the design can reduce overall drive power requirements vs. conventional conveyors by as much as 30% on a horizontal run. 

Pursuit of Perfection
“Even in the best of installations, the troughing idlers in conventional systems can’t provide a perfect belt line,” Baxmann continued.  “The up-and-down motion agitates the material, which can cause some particles to become airborne.  That disturbance can also push some material to the outside edges of the belt, where it might be spilled.  The stable belt path of the air-supported system minimizes turbulence and the resulting fugitive material.”

The air-supported design also eliminates maintenance issues such as idler replacement and belt alignment, and the modular system allows replacement of existing conveyor sections with CEMA standard construction.  Air-supported and conventional roller sections can be integrated to accommodate loading zones, tracking idlers, belt scales or other needs. 

On new conveyors, the air-supported systems are engineered to suit specific requirements, able to span longer distances and higher inclines than conventional systems.  By eliminating idlers and pinch points, the air-supported system further reduces maintenance requirements and potential safety risks. 

The Emden plant reports extremely low- maintenance service from the air-supported design.  The conveyor has exceeded the company’s 98% operational requirement, and the fully-enclosed system prevents the escape of dust.  The facility converts approx. 130,000 metric tons of biomass into energy each year, with the conveyor transporting 110-120 metric tons per hour.

Air-Supported Conveyor Systems are employed around the world in a wide variety of bulk material applications, including wood chips, pellets, grain, crushed coal, rock/aggregate, cement/clinker and mining. 

Werner Baxmaan is the European Sales & Marketing Manager for Martin Engineering.

Engineered Coal Chutes Reduce Maintenance, Extend Belt Life

[Superior, WI] -- A high-volume coal transshipment terminal at the western edge of Lake Superior has eliminated material backups and reduced maintenance -- while extending conveyor belt life -- with custom-engineered transfer chutes.  Designed and constructed specifically to address the flow rate and physical characteristics of the terminal’s coal, the chutes have helped to avoid blockage and minimize fugitive material, reducing costly interruptions to clear plugged sections of chutes and clean up spills. 

One of the challenges for Superior Midwest Energy Terminal was the ambitious loading schedule, which doesn’t afford much opportunity for maintenance and equipment changes.  Downtime is limited, with system upgrades handled during the annual January and February maintenance outages.  That emphasis on maximizing performance, coupled with the willingness to make investments that will maintain efficiency, led the terminal to install custom-engineered chutes from Martin Engineering of Neponset, Illinois.

Uptime is Key
Director of Terminal Operations Marshall Elder explained: “We load ships around the clock, so it’s difficult to find time to make changes to our system.  We cannot keep vessels—and our customers—waiting for coal while we make changes to our equipment,” he said.  The entire transfer chute system was designed and constructed off-site by Martin Engineering, then installed in just four weeks of scheduled downtime.

Superior Midwest Energy Terminal handles approximately 22 million tons of western coal annually.  The terminal unloads the unit trains bringing coal from mines in the Powder River Basin and transfers it onto vessels for transport to utility power plants in the U.S. and Canada.  Located on a 200-acre site at the mouth of the St. Louis River, the 30 year-old facility has become one of the largest coal handling terminals in the world.

To receive its coal, the terminal unloads more than 1,400 trains from the Burlington Northern and Santa Fe (BNSF) and Union Pacific railway lines each year.  “We unload railcars at 5,000 tons per hour, roughly 45 cars an hour, or a full 123-car train in about three hours,” Elder observed.  The terminal then loads that coal onto approximately 450 vessels during a 305-day shipping season.  Shiploading operations run from late March until mid-January, when ice closes the Wisconsin port.

According to Fred Shusterich, President of Midwest Energy Resources Company (MERC), a DTE Energy Company that owns and operates the terminal, “This is the largest-capacity coal terminal having only one single-car railcar dumper.  We put more coal through that single-car dumper than any operation in the world,” he said.

“MERC is a high volume operation,” Shusterich emphasized.  “And because of that fact, we aim high and make the investments to maintain peak performance levels of our primary coal-handling operations.”

Benefits of Custom-Engineered Chutes
Engineered specifically for the Superior terminal, the MARTIN® INERTIAL FLOW™ Transfer Chutes have minimized previous problems with plugging.  “When a chute used to plug up, the material would spill onto the floor and around the conveyor idlers,” Elder explained.  “And at 11,500 tons per hour, it doesn’t take long to put a large volume of material outside the chute.  That’s a lot of spilled coal, and a lot of man-hours to clean it up.  Minimizing the plugging problem has been a very positive aspect of these engineered chutes.”

Inside each chute, a “hood” controls the flow of coal from the discharging conveyor, maintaining a coherent material stream and minimizing induced air.  At the bottom, a smooth-transfer loading chute or “spoon” directs the material stream onto the receiving belt at the proper speed and angle, minimizing the impact, material degradation, belt abrasion and expulsion of airborne dust.  This reduces abrasive wear on the receiving belt and prevents the air currents that create and drive off airborne dust.

The terminal is anticipating another benefit from the chutes: longer belt life.  “That’s one of the key reasons we went to the engineered chutes,” Elder continued.  “We anticipate an increase in belt life of approximately 40%, primarily because of the reduced abrasion realized with the new chute design.  We anticipate getting seven or eight years of service out of our major belts, or between 175 and 200 million tons of throughput.”  Elder said the company monitors the conveyor belt top cover, which ultimately determines when the belts will be replaced.

The performance of the MARTIN® INERTIAL FLOW™ Transfer Chutes is helping Superior Midwest Energy Terminal maintain efficient operations and reliable supply.  “We pride ourselves on the volume of material handled, and on our dependability,” Shusterich added.  “We know it’s more than western coal we are delivering.  We are providing power to communities, so we need to be consistently available and operating at peak efficiency.  The engineered chutes from Martin Engineering help make that possible.”

“The flow-engineered chute technology provides obvious advantages,” Elder concluded.  “I don’t know why any new facility design would incorporate anything else.”