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Copyright © 2004 Barbara L. „Bobby” Baker
All American Resources, Inc.
The information provided in this material is meant to provide general information
for personnel not familiar with general centrifugation terms and operational
functions. It was not compiled to serve as technical training or as an operations
manual.
Exclusive U.S. Agent for Hutchison-Hayes Separations, Inc.
All American Resources, Inc. was started by Barbara L. “Bobby” Baker in 1999 with 15 years of site
service experience and 25 years of business experience. The goal then and now is to provide 24/7
Equipment, Service and Supply sourcing support for Project Managers, Site Supervisors and Maintenance
Engineers on Industrial related Field Service Projects. On site service expertise includes Remediation,
Separations, Waste Minimization and Product Recovery.
AAAllllll---AAAmmmeeerrriiicccaaannn RRReeesssooouuurrrccceeesss,,, IIInnnccc... Exclusive U.S. Agent for Hutchison-Hayes Separations, Inc.
38466 B. Baker Lane, Gonzales, La. 70737
Website: aacentrifugerentals.com
Office: 225-928-9406 Fax: 225-208-1261 Mobil: 713-410-6178
Copyright © 2004 Barbara L. „Bobby” Baker
Click on rig for slide show and
technical information on 5500.
AARI
Copyright © 2004 Barbara L. „Bobby” Baker
Industrial Process Site
Mob in/Rig up Site Tips
Confirm that the equipment you will be using is Explosion Proof
(NEMA 7) and meets all OSHA safety standards including noise
standards. Hutchison Hayes rental equipment does meet these
standards.
Save time and acquire proper rig up permits prior to the
equipment‟s arrival at the site.
Make sure a crane is designated for the site so off loading of trucks
can be performed without delay. Bring slings to use for the proper
(safe) lifting of equipment. Nine out of ten times the plant
operators do not have the proper rigging for handling the weight of
centrifugal equipment.
Use a quality liner (NOT VISQUEEN) for leaks and spills under
all tanks and process equipment. Check with facility on their site
requirements prior to mobilization.
Place boards under all equipment in order to 1) be able to clean
underneath and prevent/control vibrations from centrifuge.
Spot all equipment before rigging up hoses, wire, etc. so that all
support rig up equipment such as crane, trucks, etc. can be
released.
Run hoses in a neat and orderly fashion so they will not be a trip
hazard. Use wire on cam locks not duct tape. Use high
temperature hoses at all times in industrial applications. Use low
temp hoses only on polymer, fresh water feed for polymer systems,
and/or coolers on back-drives. Build walkways over hoses in high
traffic areas.
Centrifuge Project at
major refinery.
Processing sludge
material from tank farm
turnaround. Nine month
project, recovering oil,
producing paint filter
solids for disposal and
water for in plant
treatment prior to
discharge.
Copyright © 2004 Barbara L. „Bobby” Baker
Make sure tees, valves, and drains are connected to hoses at one
end to anticipate change out of hoses and changes in the process
flow diagram and for de-con at the end of the project.
Always have washtub(s) on location along with blank cam lock
plugs for exchanging hoses.
SAFETY FIRST
Run wire 10 feet off the ground. Carefully check points where
wiring comes in contact with metal. Take steps to prevent wiring
from being rubbed of its insulation by checking all metal contact
points that could result in electrical shock or an explosion.
Ground the generator with an 8-foot ground rod buried in the
ground with only 2 inches extending above the ground.
Note: If no generator is on this job site then the equipment must be
grounded in the same manner or possibly the plant will allow you to
ground to their facility grounding system.
ALWAYS MAKE SURE YOU ASK FIRST. Make sure everything
is grounded with #6 ground wire are as indicated by facility personnel
in charge of electrical approval. Flag all electrical wire with proper
electrical caution tape.
1. Make sump on lowest corner of location and rig up pump to pump off
excess rainwater or spills.
2. Use the appropriate Caution tape to flag off the entire location.
3. Checking rotation should only be done after you have received proper
permits.
4. Acquire proper work permits to rig up and install equipment.
5. Hold safety tailgate meeting prior to rig up and review all MSDS
information on chemicals to be used and materials to be processed.
6. Check all safety equipment and personal protection gear to make sure
it meets OSHA and Facility Safety Standards.
7. Never leave one person on a job site. Remember the TAKE TWO for
safety rule.
8. Pre-screen materials with a shaker/tank system prior processing to
avoid plugging and equipment damage due to trash and debris.
Copyright © 2004 Barbara L. „Bobby” Baker
9. Confirm that the proper power and panel connections for the
equipment to be used have been met.
Basic centrifuge terminology follows with these headings:
Decanting Centrifuge
Operational Information
Centrifuge Feed System
Screw Conveyor/Solids
Discharge
Screw Conveyor/Effluent
Weirs
Effluent Weirs
Centrifugal Force
Variable Speed
Feed Flow Rate
Pool Depth
Weir Plate Adjustment
Differential Speed
Conveyor Speed
Conveyance Speed
Gearbox Ratio
Decanting Solid Bowl Centrifuge Operational Information
Industrial decanting centrifuges process liquid/solid slurries at a high
g force generated by the rotation of the centrifuge bowl. Higher
specific gravity solids are augured from the solids portal into holding
boxes and liquids are discharged from a separate effluent point.
Generally speaking the particle size distribution for the solids
involved in industrial separation activities are well under the 100-
micron range.
Centrifuge Feed System
The centrifuge is fed through a pipe, which is inside a hollow shaft
connected to the screw conveyor or scroll. The feed slurry enters a
compartment located inside of the conveyor. It is then accelerated
through feed ports into the inside of the bowl section. Centrifugal
forces accelerate the solids, they are collected on the inside diameter
of the bowl wall and the liquid forms a concentric annulus and fills
the bowl to the level of the effluent weirs.
Copyright © 2004 Barbara L. „Bobby” Baker
Screw Conveyor/Solids Discharge
The screw conveyor is connected through a splinted coupling to a
gearbox and turns slightly slower than the bowl assembly. The helix is
angled in a manner to remove the settled solids toward the small
diameter (beach or conical section). These solids are then conveyed
along the inside diameter of the bowl to the solids discharge port.
Screw Conveyor/Effluent Weirs
The liquid flows around the screw conveyor and exits through effluent
weirs located on the large diameter (cylinder) end of the bowl. Solids
that settle to the inside diameter of the bowl are discharged with the
liquid across the effluent weirs. These solids tend to be in the
5 micron and lower range. Ninety five percent of all particles above 5
microns should be removed in this process but heat and chemical
enhancements may be necessary to achieve this goal in some streams.
Model 5500 High G Decanter
Telescoping
stand
12’ auger section
solids discharge
Effluent
discharge
Line.
Copyright © 2004 Barbara L. „Bobby” Baker
Effluent Weirs
Effluent weirs that are adjustable control the amount of liquid inside
the bowl. The maximum volume or pool depth forms an annulus
diameter, which is smaller than the solids discharge diameter. The
liquids always flow to the cylinder end.
Centrifugal Force/G-Level
A good example of centrifugal force would be the high speed mid way
rides that cause an outward force on your body as it rotates. The
intensity of the force is dependent upon the rotational speed.
The force tending to move the object or particle away from its
rotational centerline is expressed as “G-Level”. This is a function of
the bowl speed and bowl diameter. The following formula is used to
calculate G levels.
Bowl RPM (2) x Bowl Diameter (ft)
6000
Fixed Gearboxes are installed on “mechanical” centrifuges
The gearbox used on a centrifuge is a two stage planetary gearbox. It is
mounted on the centrifuge-rotating unit and is rotated at the bowl speed.
Machines have to be turned off and gearbox settings reset to alter this
setting.
Variable Speed – Hydraulic controls on bowl and/or scroll
External hydraulic and electric controls can be installed to allow for a
change in settings on the bowl and/or scroll speeds. If not speed is fixed by
the design of the motor RPM and sheave sizes.
Copyright © 2004 Barbara L. „Bobby” Baker
Machine Variable Settings
Speed (RPM), feed flow rate (GPM), pool depth, gearbox ratio, differential
speed, conveyor speed and conveyance speed.
Speed (RPM)
1. Increases or decreases the G level
2. Increases or decreases the differential speed and resonance time of the
settled solids (how fast the settled solids are removed by conveyor).
3. Alters the particle size distribution in the cake (solids) as follows:
a. Higher speed settles more solids inside the
diameter of the bowl and fewer solids in the
effluent (product). In classification this makes a
finer cut (more G‟s to settle solids, higher G seconds).
b. Lower speed settles less solids in the bowl thereby
Sending more in the effluent.
4. Increases or decreases cake moisture.
Feed Flow Rate
1. Increase of the flow reduces the time the slurry is in the bowl
(residence time).
This will usually:
a. Increase the amount of solids in the effluent phase.
b. Sometimes it will affect the solids moisture content.
c. In classification (partial size segregation) it will decrease the
separation efficiency of the machine and coarsen the cut.
2. Decrease in the flow increases the time the slurry is in the bowl
(residence time).
This will usually:
a. Decrease the amount of solids in the effluent phase.
b. In classification it will increase the separation efficiency of the
machine and make the “cut” finer.
Copyright © 2004 Barbara L. „Bobby” Baker
The flow rate is adjustable while the machine is in operation. Flow rate
should not vary more than 2-3% or it will effect the particle size distribution
in classification of particles.
An increase in the flow rate will also increase the pool depth due to the
effect of the head, which overflows the weir plates.
Pool Depth
The weir plates on the liquid end of the machine control the pool depth. By
increasing the pool depth i.e. going from 1” to 2” we increase the pool
volume (deeper pool). The same occurs when you reduce the pool level you
reduce the pool volume.
Weir Plate Adjustment
The effects of pool depth follow:
Decrease (going from 3” to 2”) in pool depth reduces the time the slurry is in
the bowl (residence time).
This will usually:
a. Decrease the amount of solids in the effluent phase.
b. In classification it will increase the efficiency of the machine
and make the cut finer.
c. Deeper pool will decrease the length of beach (conical end of
bowl) not covered by the pool. Typically this will increase the
moisture of the discharged cake solids.
Note: Pool depth cannot be adjusted while the machine is in operation.
Gearbox Ratio
Typically the gearbox ratio is fixed. It is a function of the design of the
gearing and usually comes in 20, 40, 116, 130, and 140:1ratios. The higher
the gearbox ratio (i.e.: 130 versus 40:1) the lower the differential speed.
The gearbox ratio affects the differential speed and controls how fast or slow
the settled solids are inventoried inside the machine. In other words how
quickly the solids are conveyed out of the machine.
Copyright © 2004 Barbara L. „Bobby” Baker
The higher the differential speed the faster the settled solids (rejects) are
removed. In classification it can affect the particle size distribution.
Differential Speed
The difference in passed between he bowl (driven by the motor) and the
conveyor (driven by the gearbox). The operating speed determines the
differential speed on a fixed ratio gearbox.
Typical effects on the material streams are as follows:
1. High Differential Speed
a. Usually produces wetter solids “cake”.
b. Tends to decrease soils in effluent due to lower residence
time of solids in the bowl.
c. In classification it can increase the solids in the effluent
due to the turbulence of conveyance (a stirring effect).
2. Lower Differential Speed
a. Usually produces a drier solid “cake”.
b. Tends to increase solids in the effluent stream due to
longer residence time of soils in the bowl.
c. In classification it can decrease the solids in the effluent
due to less turbulence of conveyance (less stirring effect).
Note: In classification some products are not affected by the
change in differential speed.
Copyright © 2004 Barbara L. „Bobby” Baker
HH-5500 fully hydraulic centrifuge
Conveyor Speed
Conveyor Speed is the rotating speed (RPM) of the conveyor. This speed is
determined by subtracting the differential speed (DS) from the bowl speed
(BS).
To find the speed of the conveyor use the following formula:
BS – DS = Conveyor Speed
Where BS + Bowl Speed and DS = Differential Speed
Conveyance Speed
The linear rate at which the solids are moved along the inside diameter of
the bowl is called the Conveyance Speed. This rate is a function of the
differential speed and conveyor lead (pitch).
Conveyance speed can be calculated as follows:
Formula: DS x CL = inches/sec. Conveyance speed
60
Where: DS = Differential Speed CL = Conveyor Lead
Example: DS = 23 RPM, CL = 12”
23 x 12 = 4.6”/sec
60
Copyright © 2004 Barbara L. „Bobby” Baker
Note: When making changes to a machine change one variable at a time to
determine the effect on the process before proceeding.
In case you did not know…….
We can provide parts and service on all
major centrifuge models. If you are
operating your own centrifuges contact
us for a quote and rates for a rental
while it is being worked on.
Hutchison Hayes Model 5500
decanter on telescoping stand at
major refinery site.
This was a six month tank
bottoms waste minimization
project (with oil recovery spec
of 5% or less BS&W).
Heat and oil/water separator
were utilized to enhance the
separation of the discharged
oil/water stream.
Copyright © 2004 Barbara L. „Bobby” Baker
External issues that affect the Centrifuge Process 1. Proper sizing of pumps, lines and connections to prevent plugging,
excessive head pressure and build-up/settling of dense materials
during pumping.
2. Proper shaker system (pre-screening apparatus) to remove all trash
that might lead to plugging and/or equipment damage.
3. Containment for the shaker overflow.
4. Agitated mix tank to enhance homogeneous feed for processing.
Note: If the material to be processed is a slurry/sludge containing water,
solids and hydrocarbons then heat and/or chemicals may be utilized to
enhance the oil recovery process. A heated effluent stream containing water
and hydrocarbons should “break” into two streams when pumped through an
oil/water separator or pumped to heated frac tank.
At the break you may get residue of oil in the water phase and a little water
in the oil phase but 5% or less BS&W should be easily reached with this
procedure until emulsions are encountered. Tricanters (3-phase centrifuges)
separate water/oil/and solids and the streams are kept separate as they leave
the bowl. With a decanter (liquid/solid) these streams are separated in the
bowl but are discharged through the same port.
Operating standards for heating materials must be reviewed by utilizing the
material‟s MSDS guidelines. The use of heat and/or chemicals in
conjunction with Special Projects work must always be coordinated with
Plant Representatives, Environmental and Safety personnel.
AAAllllll---AAAmmmeeerrriiicccaaannn RRReeesssooouuurrrccceeesss,,, IIInnnccc... Exclusive U.S. Agent for Hutchison-Hayes Separations, Inc.
38466 B. Baker Lane, Gonzales, La. 70737
Website: aacentrifugerentals.com
Office: 225-928-9406 Fax: 225-208-1261 Mobil: 713-410-6178