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General
The process of controlled heating, cooling, and
classification of sand passing through this unit is achieved by the balanced
use of air from a supplied blower and heated or cooled water in the form of
a heat exchanger bundled designed integrally in the unit. This ensures that
the sand being discharged from the unit is not only at the temperature best
suited to the customer’s operation, but is also free of dust and matches the
desired grain distribution of the sand.
Mechanical Components
The HCCL-Series classifier is constructed from
four major components:
- A base, or plenum chamber, into which
fluidizing air is supplied by a blower.
- A fluidizing deck
- A heat exchanger bundle.
- A main body, which serves as a cover and
pressure chamber
The plenum chamber serves not only as
a base, but also a means of distributing the incoming air to the
underside of the fluidizing deck. The deck is an abrasion resistant
steel plate containing self-cleaning orifices through which the air
is passed through in order to fluidize the sand resting on it. The
fluidization orifices are covered with abrasion strips which prevent
sand from falling into the plenum. The fluidization action brings
each grain of sand in intimate contact with the heat exchange
bundle, which is mounted on top of the fluidizing deck and is made
up of steel tubing mounted in close proximity between two water
manifolds. The main body is mounted on top of the base (plenum
chamber) and over the heat exchanger bundle. It serves not only as a
cover, but also as a heating and classifying chamber.
The fluidizing action of the sand not
only contributes to heating and cooling, but also polishes each
grain, removing the dust and fines that exist naturally in the sand
source as well as those created in the transportation of the sand to
the HCCL. A negative pressure maintained over the bed by a dust
collector (supplied by the customer or as an option) and controlled
by a dam gate located between the dust collector and the
heater/cooler/classifier ensures that all the dust and fines are
removed from the chamber and around the sand grains.
Fluidizing air is provided by a
constant pressure blower driven by a TEFC motor that includes an
inlet damper control. Inspection and cleaning panels, flanged
discharge, dust collection, and air manifold connections are
included. The fluidizing air blower can be mounted on either side of
the heater/classifier to suit the customer’s layout.
Sand throughput is regulated using a
high quality butterfly style inlet valve. This valve actuates at the
initiation of the cycle to meter sand into the unit. The concept of
fluidization imparts that for every pound of sand poured into the
unit, one pound will come out. The purpose of this valve is not only
to meter the sand, but also to shut off the sand supply at the end
of the cycle. This ensures that the classifier body does not pack
full, maintaining consistent fluidization pressures and rates.
Heating water is supplied to the heat
exchanger from a natural gas hot water boiler, unless otherwise
specified. The boiler coupled with standard high resolution
Honeywell temperature controller ensure constant exit temperatures
even on the coolest day. An atmospheric hot water natural gas
heating boiler is supplied as standard equipment.
Cooling water as standard would be
supplied from city or natural well water. However, the system is
easily adapted to include cooling tower or chiller controls.
Temperature in cooling mode is controlled by the same Honeywell
controller as is used for heating, simplifying controls and
operation.
Controls
The standard control system includes all
components necessary for the operation of this unit. All primary
operating components are Allen-Bradley, the control transformer is
ACME, and the temperature controller is Honeywell. These components
are all off-the-shelf and available from high quality industrial and
electrical supply houses.
A modulating valve, included as
standard, regulates the flow of either cooling or heating water to
the unit. This regulation is controlled automatically using a PID
control loop. The closer the sand is to the desired process
temperature, the less water will flow through the heat exchange
bundle. The heating system is closed loop as standard. The cooling
system, if using city water is either sent to drain or to cooling
tanks. With the optional cooling tower or chiller package, the
cooling loop is closed as well, minimizing water consumption year
round.
The unit comes standard with all control
logic necessary for the automatic switching from heating to cooling.
Hardware for this (electrically actuated
diverter valves) is optional. Generally, all system valving and
piping to the unit is customer supplied as all shops have different
preferences for brand, type, routings, etc.
A rotary style level indicator controls
the operation of the unit. Located in the discharge hopper, the HCCL
seeks to maintain a full state. A run time timer initiates when the
level indicator is clear. This insures that a certain surge capacity
is always available.
General Specifications
- Tonnage and thermal transmission
rates are based on silica sand (50-75 AFS).
- Heating Parameters:45
degrees Fahrenheit Incoming to 85 degrees Fahrenheit Discharge
(Controlled) - Heating Energy Source - Natural Gas Hot Water
Boiler
- Cooling Parameters:105
degrees Fahrenheit Incoming to 85 degrees Fahrenheit Discharge
(Controlled) - Cooling Energy Source - City Water at 65 degrees
Fahrenheit
Detailed Specifications
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