Hogg
Fuel & Supply operates concrete batch plants in Ontario,
Canada. Hogg Fuel has been a quality supplier of ready mix
concrete for over thirty (30) years. They use a blend of Portland
cement and slag. The “slag” is actually GGBS or
ground granulated blastfurnace slag. GGBS is sometimes used
as an additive to concrete to provide benefits in the areas of durability,
quality, strength and finish. Typical batches include about
10-15% slag but this can vary depending on the need of their customer.
Maintenance Supervisor Bob Knarr was looking to replace the older
weight & cable units installed on their 20ft (6.1m) cement and
slag storage silos. Although the weight & cable based technology
provided accurate distance measurements, they required maintenance
several times per year. Bob and Hogg Fuel wanted a measurement
system that would be would not require maintenance, would provide
true continuous readout, provide the accuracy they require, while
retrofitting into the existing mounting portals on top of their silos.
This
plant was designed as an auxiliary plant to their main facility and
therefore was built with smaller capacity silos than their main plant. However,
this auxiliary plant has become increasingly busier in recent years.
This makes tracking the level critical as loads are required more
frequently than in the past.
Flexar has met all of their expectations and system requirements. As
with all complete systems, Hogg Fuel has a rotary paddle point level
unit top mounted with a two foot extension for indication of high
level to alert the cement delivery to shut down when the vessel is
full. As an added bonus, Flexar provides the batcher in the
control room the ability to track the progression of the fill cycle
right to its completion! The Flexar sensors were installed
in late April 2006.
Flexar is a guided wave radar continuous level sensor. Distance/level is
measured by the time-of-flight of the reflection of a microwave signal (transmitted
down the wave-guide, which is a heavy-duty 0.3” SS cable with 3.9 ton tensile
strength) off the material surface. Cement and GGBS slag both have relatively
low dielectric constants and Flexar’s direct measuring mode
was successful in providing real-time continuous updates of the material
level during filling and draw-down.
Spotlight: Solids Flow Detection
Solids Flow Detection
Microwave solids flow detectors can
be used in a variety of applications including feed mills & grain processing,
consumer foods (cereal, sugar, cocoa, coffee), chemicals & pesticides
and more. For example, one company uses Monitor’s Model SFD-2
solids flow detector to verify the flow of feed pellets through their
various transport lines which involves a process where a horizontal
screw auger is conveying pellets over to a vertical gravity chute. The
chute then directs the pellets to a process down below. They have
carefully placed the SFD-2 so that it detects the pellets as they
fall directly across the sensor face. (See Below)
The Model SFI and SFD-2 line of solids flow detectors
from Monitor Technologies, LLC provide analog or relay outputs to
indicate the flow / no-flow condition of powder and bulk solids materials
in chutes and pneumatic conveying lines. Using microwave Doppler
radar technology these units are non-invasive plus extremely reliable
and rugged to withstand the rigors of the installation and your process
extremes. From automated systems with pneumatic lines to gravity
chutes, solids flow monitors can help to improve process performance.
They can assist in detecting flow problems, as well as, enhance the
level of automation at a facility like turning a conveyor on or off.
For more information on Solids
Flow Detectors
click here or contact Monitor Technologies LLC at 800-766-6486
in the USA and 630-365-9403 worldwide.
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This
plant was designed as an auxiliary plant to their main facility and
therefore was built with smaller capacity silos than their main plant. However,
this auxiliary plant has become increasingly busier in recent years.
This makes tracking the level critical as loads are required more
frequently than in the past. 
Weight
& Cable Based