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Asphalt Producer
Asphalt Plant Roundup
New and improved are the bywords to consider.
by Tom Hogarty
As part of our special focus on asphalt plant and facility controls,
Better Roads editors sought input from companies who market these products
to the industry-at-large.
The response yielded information of products including custom-designed
asphalt plants (Almix and Hotmix); single drum mixers (Maxam Equipment),
dual-drum mixers (ADM
Milemaker); high-temp filter bags (Destex); control
house (Astec); portable baghouses (Aesco/Madsen); a combination asphalt
batching, silo loadout, and truck scale ticketing system (Libra); and a
recycling plant (RPM).
In each instance there is ample proof that the concept of continuing
research and development is constantly at work to produce new and improved
industry products.
Aesco/Madsen
Baghouse
 Aesco/Madsen sold its first high-ratio baghouse three years ago to an
Alberta, Canada-based sand and gravel plant. “Our objectives were to
provide a plant to meet, or exceed, production estimates, provide
state-of-the-art pollution control, and be highly portable,” said John
Ferris, Aesco/Madsen’s founder and CEO.
The company’s prototype baghouse was rated at 25,200 cubic feet per
minute and had 2,615 square feet of cloth, yielding a 9.6-to-1
air-to-cloth ratio at maximum airflow. Subsequent designs “taught us
more than we thought we ever knew about the real operations that occur
inside a baghouse,” said company Sales Manager Steve Malloy. The result:
an evolving baghouse which became more efficient and smaller with each
successive evolution.
The final design resulted in a baghouse which brings horizontal airflow
into the side of the baghouse, under the tube sheet. Bars in front of each
row of bags protect the bags from abrasion. The company also looked at bag
spacing, using fewer bags, placed farther apart — and at development of
a more efficient cleaning mechanism. Company research had shown that in
most cases the top part of the bag was plugged with dust due to venturi in
the cage, a fact which also caused large pressure drops in the operation.
Eliminating the venturi lowered the pressure drop, and the introduction of
a high-pressure nozzle filled the bag’s throat, and stopped any airflow
loss. Finally, by developing a means to eliminate accumulating dust cakes
— thereby keeping pressure constant — while maintaining the filter
cake porous, the filtering process became more efficient.
Result: satisfied customers.
In 2002, Aesco/Madsen sold three of its HRB-544 portable baghouses,
each with 5,269 square feet of cloth. One had a rating of 50,000 cubic
feet per minute for an air-to-cloth ratio of 9.5 to 1, a second produced
55,000 cubic feet per minute for an air-to-cloth ratio of 10.4 to 1, and
the third rated at 56,000 cubic feet per minute at an air-to-cloth ratio
of 10.6 to 1.
User comments testify to the baghouse success “proving that the
contractor can run at lower-pressure drops, less bags and cages, and
reduced energy consumption — all factors which lower their per-ton cost,
with a baghouse that is much smaller than currently accepted asphalt
industry standards, Aesco/Madsen’s Steve Malloy said.
Click 36 on ROADFAX card
Libra Systems Corporation
All-in-one system
 Harleyville, Pennsylvania-based Libra Systems Corporation has come
online with its Generation 3 Asphalt Batching, Silo Loadout, and Truck
Scale Ticketing System, with a design allowing it to fit specific and
changing needs of the asphalt producer. With its built-in utilities,
producers may create new fields, make selector lists, add fields to the
ticketing screen, layout tickets, design reports, and construct the
electronic transaction file.
“The system’s database architecture and software allow easy
integration with Libra’s office products or your company’s accounting,
database, and spreadsheet applications,” according to Libra Systems’
Kenneth Cardy. Its comprehensive reporting capabilities allow the producer
to generate reports over any date range, preview reports on-screen, add
charts to reports, show detailed or summary information, export reports
into many formats, and convert them into Web pages.
Generation 3 operates in a multi-tasking environment, allowing many
tasks to occur simultaneously. “More specifically, the plant operators
can be weighing trucks on multiple scales and, at the same time, the
office can call in and update files, retrieve data, or generate reports,”
Cardy said. “Office tasks are completely invisible to the operators and
do not interfere with their work,” he said. The Generation 3 system also
offers an extensive security system, allowing the producer to tailor
access privileges to fit its needs.
Click 37 on ROADFAX card
RAP Process Machinery Corp.
Recycling
RAP Process Machinery Corporation, Ramsey, New Jersey, has a new
patented asphalt recycling equipment technology which it markets as The
Rapmaster. “The units are capable of processing from 70 to 300 tons per
hour of RAP into new hot-mix asphalt — usually at a fraction of the cost
of virgin material hot-mix,” RAP’s Larry Hanlon said.
“Under controlled conditions, where surface course RAP milled from
roads is to be replaced, the portable on-site plant can process the RAP
and, using the process, treat it with a precise amount of rejuvenating
agent additive,” he explained. The additive revitalizes the original RAP
asphalt content, returning any characteristics lost during surface
oxidation.
The company lists some impressive money-saving scenarios. For example,
360,000 tons of RAP includes approximately 5% bitumen — approximately
18,000 tons of asphalt cement. At today’s market value of approximately
$175 per ton, the economic recovery value is $3,150,000. And that’s
exclusive of any stone recovery.
Rapmaster is an independent plant. Its product output can be used for
direct specification paving applications or combined with existing batch
or drum-mix plants production to further enhance RAP processing
capabilities. The plant meets all current federal and state clean-air
standards, and is highly transportable. Because the plant uses an isolated
hot-air stream, there is no particulate carry through. As such, no costly
baghouse is required. Generally speaking, the Rapmaster fits in a smaller
footprint than most conventional asphalt plants available today. The
manufacturer also claims that any blue smoke created during the heating
process is completely incinerated in the plant’s combustion chamber.
Click 38 on ROADFAX card
Hot Mix Industries
High-production asphalt plant
 Hot Mix Industries, Boerne, Texas, offers its Model HMI-275 asphalt
plant, which boasts of a production range over 300 tons per hour. Other
features, according to HotMix spokesperson Patrick Ahearn: “Load-out
tickets are automatically generated from the weigh batcher, which is
suspended from an 80-ton heated silo with a full-welded steel skin,
wrapped around 3 inches of insulation and abrasion-resistant cone liner.
Ahearn says that the plant also has “an exclusive relocation baghouse
design” as well as a steel-skin 30,000-gallon hot oil-heated split
asphalt tank, insulated drum, and 309-ton aggregate bins with incorporated
scalping screens. “Federally approved DOT interstate work is being
completed with this plant,” Ahearn reports.
Click 32 on ROADFAX card
Astec
Control house
 Operating on a Windows NT platform, the Astec TC 2000 Control House
controls and monitors all plant functions — including blending
operations, plant motors, motor currents, mix and plant temperatures,
material inventory, silo levels, energy usage, and alarm status — from a
standard PC.
The system is distributed I/O over an industrial
communications network, which reduces wiring, thereby making the system
easy to install or disassemble.
Click 35 on ROADFAX card
Asphalt Drum Mixers, Incorporated
Drum mixers
Now in its 13th year of use, the line of drum mixers produced by
Huntertown, Indiana-based Asphalt Drum Mixers has reached a point of
technological refinement to where its line of portable and stationary
asphalt plants — initially capable of producing over one million tons of
asphalt — now regularly produce from 160 to 425 tons per hour.
These fuel-efficient plants were specifically designed to deliver the
mix quality required to help asphalt producers meet increasingly tight
state and federal specs, efficiently process high percentages of RAP, and
efficiently add and blend additives and modifiers. Dependant on plant
size, the Milemaker line offers “the longest drying and mixing times in
the industry,” a company spokesperson said, with separate drying and
mixing drams combining for drum lengths ranging in size from 40 to 54
feet. The company reports that it has over 650 plants in operation today,
in sizes ranging from 30 to 425 tons per hour.
Click 33 on ROADFAX card
Maxam Equipment
Single drum mixers
 Maxam Equipment, Kansas City, Missouri, has introduced a new drum mixer
design, the Maxam SOLO, which, the company says, “guarantees 50% recycle
while maintaining a 250 degree stack.” Approaching its 15th year in
business, the company has produced “the first design to allow a high
percent of RAP (50% +) while maintaining a low stack temperature. The
Mixer’s heat recovery system automatically controls stack temperature
plus or minus 5 degrees, regardless of production rate of mix design, the
company says, adding that the single drum’s other efficiencies include
20% greater production, peak fuel usage, lower maintenance costs, and the
ability to use polyester bags.
Click 39 on ROADFAX card
Destex, Incorporated
Filter bags
 High-temp filter bags, made from 100% aramoid fiber, are offered by
Albany, New York-based Destex. The bags are made with heavy-duty
stainless-steel snap bands, which help provide the tight seals critical in
achieving maximum baghouse performance.
Click 34 on ROADFAX card
Almix
Stationary and portable asphalt plants
Almix, of Fort Wayne, Indiana, produces a line of both stationary and
portable asphalt plants custom designed to fit producers needs and
budgets. Its plants have standard production ranges from 40 to 550 tons
per hour, and its hot-mix handling systems range from 30 to 330 silos
capable of accommodating long-term storage requirements. A feature of the
Almix product is its Duo Drum, which isolates the mixing process from the
drying process in order to maximize the plant’s drying and combustion
efficiency. Mixing is conducted in an inert environment; any fugitive
emissions or odors are captured and incinerated through the burner path.
Click 31 on ROADFAX card
Reprinted from Better Roads Magazine
March 2004 |
