AIR CANNONS BOOST MATERIAL FLOW, ELIMINATE BIOMASS BOILER FOULING

Shown here are the Koda Energy fuel receiving and storage area on the right, the electrical substation and step-up transformer on the left, and the boiler house in the center.	Martin Engineering crews installed 12 Big Blaster® Hurricane Air Cannons at Koda Energy to remove ash buildup from the boiler walls and tubes.

An innovative Minnesota energy company has eliminated labor-intensive air lancing to clean biomass ash from boiler walls by installing a series of high-powered air cannons to dislodge accumulations and restore process flow.  The air cannon network at Koda Energy (Shakopee, MN) helps the facility avoid the daily shutdowns and maintenance hours that manual cleaning required, allowing the facility to run at its rated capacity.  Programmed to fire in a prescribed pattern, the system from Martin Engineering is fully automated, but can be fired manually if build-up becomes evident through the view ports.

“Efficient material flow is a critical element of biomass-fired boilers, and accumulation or blockages can take a big bite out of a plant’s efficiency,” explained Martin Engineering Service Technician James Millis.  “Ash build-up on furnace walls and tubes can choke the process, degrading equipment performance and introducing the potential for safety risks during cleanout.”

Koda’s combined heat and power (CHP) plant burns approximately 500 tons of biomass fuel each day to generate a capacity of 24 MW per hour.  A partnership between Rahr Malting Company (RMC) and the Shakopee Mdewakanton Sioux Community (SMSC), the plant is ideally located next to the malting facility, where a consistent supply of biomass fuel is readily available.

The generating plant uses 100 percent biomass fuel in a McBurney high pressure biomass boiler with an output of 220,000 pounds of steam per hour.  The electricity generated via turbine serves Koda Energy as well as the adjacent Rahr Malting plant.  Approximately half of the power generated is sold to Xcel Energy, while waste heat from the boiler is recycled back to Rahr, replacing the natural gas previously used in the malting process.

When maintenance crews noticed significant build-up early in the plant’s operational life, they first addressed the issue using a special fuel additive that was purported to reduce furnace fouling, but the results were disappointing.  “We found the additive approach to be expensive and largely ineffective,” said Koda’s Chief Engineer and VP of Operations Stacy Cook.

Instead, the company turned to manual cleanout techniques using an air lance.  The method was more successful at removing the ash, but it required a daily work stoppage to complete the time-consuming process.  “Daily air lancing did remove the build-up, and helped us maintain full output, but we couldn’t reach all areas within the boiler,” Cook continued.

“It also affected our production schedule and posed a potential safety risk for plant personnel,” he said.  “To make matters worse, we were facing the possibility of a monthly shutdown to thoroughly clean out the boiler.”

An Air-Powered Solution
During a visit from Martin Engineering to explore the use of air cannons in another part of the process, Cook reviewed the fouling problem and asked whether the technology might be useful for preventing ash build-up on the boiler walls and tubes.  “We decided to try the air cannons first for cleaning those areas that were inaccessible with a hand lance,” Cook explained.  “Our thought was that it would be a good way to gauge how effective they might be for this application.”

The initial installation showed promise as a way to eliminate the hand lancing, and together with Martin Engineering technicians, Koda developed a plan to expand the air cannon system.  Over the course of three planned maintenance outages, Martin Engineering crews installed a total of 12 Big Blaster® Hurricane Air Cannons.  Introduced by Martin Engineering in 1974, air cannon technology has since developed a proven track record around the world for relieving bottlenecks caused by material buildup in high-capacity storage and process vessels.

The Hurricane Air Cannon is a positive-acting, internal valve design from Martin Engineering, developed specifically to deliver maximum force output from a very direct air path, requiring minimal air consumption and a small footprint.  By producing more power from less air, it uses a smaller reservoir, which in turn allows the Hurricane to fit into smaller spaces.

By activating the solenoid valve, a positive pressure signal is sent to the Hurricane’s exhaust valve, causing it to actuate and release the pressure holding the piston.  The piston is instantly forced back by the air pressure stored in the tank, and the blast of air is then directed through the nozzle and into the boiler.

Because it fires only in response to a positive surge of air sent by a solenoid, the Hurricane valve will not discharge accidentally in response to a drop in pressure, such as might occur from an air supply failure or broken line.  The specially-designed valve allows the control solenoid to be positioned as far as 200 feet (60 meters) from the tank, helping to keep solenoids away from harsh environments and difficult service conditions.

“Before we installed the air cannon system, we had to manually air lance the boiler every day to maintain adequate heat transfer in the wall tubes,” Cook continued.  “Since the installation was completed, we’ve been able to maintain full boiler output without any hand lancing,” he said.  “That has allowed us to keep the boiler wall surfaces clean, while avoiding the manpower requirements and potential hazards associated with hand lancing.  We can now run the system at its rated capacity, without the negative effects previously posed by boiler fouling.”

The operation has been so successful that the Minnesota High Tech Association (MHTA) named General Mills and Koda Energy as finalists in the Innovation Collaboration of the Year category for the 2010 Tekne Awards.  The Tekne Awards recognize Minnesota companies and individuals who have shown superior technology innovation and leadership.

“If they become severe enough, flow problems can bring operations to a complete stop until the problem is corrected,” Millis added.  “Although many facilities still use manual techniques to remove boiler build-up, the costs of labor and production shutdowns have prompted some plants to investigate more effective methods for dealing with this type of flow issue.”

The 12 air cannons feature a positive-acting, internal valve design,
developed specifically to deliver a direct air path, maximum force
output and minimal air consumption with a small footprint.

 

---

THE NEED TO IMPROVE EFFICIENCY AND MAINTAIN PRODUCTION WITHOUT OUTAGES LED COMPANY OFFICIALS TO CONSIDER WAYS TO IMPROVE FLOW THROUGH LAFARGE BRESIL S.A. PRE-HEATER TOWER.

The Lafarge Bresil S.A. plant in Matozinhos, Brazil produces 660,000 tons (600,000 metric tons) of cement per year.

The BIG BLASTER® Air Cannon shown in this photo is painted blue to match the standard for this plant.

INDUSTRY: Cement
PRODUCT: BIG BLASTER® Air Cannon with MARTIN® TORNADO Exhaust Valve
SITE: Lafarge Bresil S.A.; Matozinhos, Mines Gerias, Brazil

Situation
The Lafarge Bresil S.A. plant in Matozinhos, Brazil is one of Brazil’s leading cement production facilities. Opened in 1959, the plant produces 660,000 tons (600,000 metric tons) of clinker per year. The need to improve efficiency and maintain production without outages led company officials to consider ways to improve flow through the plant’s pre-heater tower.

Solution
BIG BLASTER® XHV Air Cannons with MARTIN® TORNADO Exhaust Valves were installed by service technicians from Martin Engineering’s business unit in Campinas, Brazil.

Results
The BIG BLASTER® XHV Air Cannon with the MARTIN® TORNADO Exhaust Valve provides a faster and more powerful discharge than previous BIG BLASTER® Air Cannon Systems.

At the Lafarge Bresil plant, the air cannons with the MARTIN® TORNADO Valves were installed roughly 40 feet (12 meters) from the solenoid valve panel without loss of charge or line pressure. The system uses 3/8-inch (9.5-mm) diameter air lines.

Unlike conventional air cannons, the patent-pending MARTIN® TORNADO Exhaust Valve fires in response to a positive surge of air pressure sent by a solenoid valve. This positive action allows a faster discharge, which amplifies the output to produce up to 20 percent more force than a standard BIG BLASTER® XHV Air Cannon. In addition, the improved air path of the new valve fills the reservoir three to four times faster than standard designs.

Martin Engineering Brazil reports that Lafarge Bresil is very satisfied with the performance of the BIG BLASTER® Air Cannon System with the new MARTIN® TORNADO Valves.

---

RAW MATERIAL WEIGH FEEDERS WITH CORRUGATED SIDEWALL BELTING REQUIRE MODIFIED MAINFRAMES.

The plant’s weigh feeders suffered carryback as a result of an inability to effectively clean the sidewall belts.

The MARTIN® QC™ #1 Heavy-Duty Pre-Cleaner was installed on a modified mainframe to provide effective cleaning without interference from the sidewalls.

Following installation of the modified MARTIN® QC™ #1 Heavy-Duty Pre-Cleaner, the corrugated sidewall belts on the weigh feeders were much cleaner.

INDUSTRY: Cement
PRODUCT: MARTIN® QC™ #1 Heavy Duty Pre-Cleaner with Modified Mainframe
SITE: GCC of America Dacotah Plant, Rapid City, South Dakota

Situation
This cement plant produces one million tons (907,000 m/ton) per year. The plant uses a total of nine weigh feeders to move the raw materials—limestone, sand, shale, and iron ore—from hoppers to the belt that conveys the material to the roller mill to be ground for kiln feed.

To contain the cargo, these feeders use corrugated sidewall belts. Given their wall height of 5.75 inches (146 mm) these belts are difficult to clean. As a consequence, fugitive material would build up under the feeders and spread throughout the facility.

Solution
To remove the residual material from the sidewall belts on the three most problematic of the weigh feeders, Martin Engineering proposed a modified version of the company’s MARTIN® QC™ #1 Heavy-Duty Pre-Cleaner. This special cleaning system incorporated an extended mounting spine to increase the distance from the mainframe to the belt. The modification raises the cleaning edge 4.64 inches (118 mm) while centering the blade between the sidewalls. This allows the corrugated sides to pass without problems.

Results

Belt cleaning was noticeably improved, and the accumulation of material under the three weigh feeders is significantly reduced.

Plant officials note that the plant has reduced clean-up chores from roughly a wheelbarrow full of material every three days, to about one-fourth of a wheelbarrow in a two-week period.

Plant officials noted these belts show significant wear, including small pockets across their carrying surface. Consequently, the belt cleaners are unable to totally clean these indentations; the plant is confident that new (smoother) belts would virtually eliminate the problem.

Martin Engineering representatives were congratulated by several employees of the Dacotah plant of GCC of America, Inc. for solving this difficult and long-standing problem.

---

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

[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.”

---