Questions
1: What are the operating principles
of the KDS machine?
2: How much heat input is required?
What are the machine temperatures?
3: What are the advantages of the
KDS Micronex™ over other grinding and drying technologies?
4: What are the power requirements
of the KDS machine?
5: Is the product is pathogen-free
and odor-free?
6: What is the production rate of
the machine?
7: How is the dryness and particle
size of the end product controlled?
8: What product particle sizes can
be obtained?
9: What emissions come out of the
KDS machine? What noise levels?
10: What is the operating cost
of one machine?
11: What is the rate of wear of
the chains and other moving parts?
12: What are the maintenance costs?
13: What are the manpower and salary
requirements?
14: Can FASC produce a larger machine
that could process more material, more quickly?
Answers
1: What are the operating principles
of the KDS machine?
The KDS machine comprises a chamber in which chains or blades
spin in a horizontal plane. The resulting centrifugal force
flings feed material against the sides of the chamber. The
material is literally blown apart due to repeated collisions
between particles, chains, and chamber sides. These impacts
squeeze some of the water out of the material. The material
also gets dried because of the heat generated by the impacts.
After pulverization, the material is pneumatically conveyed
to a cyclone where the moist air and product are separated.
The product is collected at the cyclone bottom. The air and
water vapor/droplets are pumped back into the machine and
the water leaves the machine through the vapor vents.
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2: How much heat input is required?
What are the machine temperatures?
ZERO heat input is required. The machine temperatures do
not exceed 90 degrees Celsius (195 deg F).
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3: What are the advantages of the
KDS Micronex™ over other grinding and drying technologies?
The following are the strong points of the KDS Micronex:
a. No heat is required, yet the KDS machine can dry organic
substances from up to 80 % moisture content down to 5 %
moisture.
b. The machine is electrically driven yet the cost of
drying per ton is less than that of drum dryers using natural
gas or propane or fuel oil.
c. The kilojoules of energy per kilogram of water removed
is 3 or 4 times LESS than that used by other dryers. In fact,
the energy required is LESS than the latent heat of water.
d. The smell from the raw material being processed is
almost completely eliminated.
e. The germs in the raw material being processed are
completely eliminated.
f. While processing mineral ores, coal or glass, very small
particle sizes (from 1 micron to 100 microns) can be achieved.
g. While grinding coal or glass to very small particle
sizes can be achieved at 2-5 times LESS energy consumption
than with conventional grinders. The KDS Micronex™ is also the only technology known
to us that can produce sub-micron glass powder efficiently.
h. The KDS machine can be used either as a grinder or as a
dryer, or both.
i. The KDS Micronex™ combines the functions of grinding
and drying in a compact, simple to operate system. By combining
the two functions, significant savings of space and energy
can be achieved.
4: What are the power requirements
of the KDS machine?
Power Requirements as a Dryer
The KDS machine combines in one machine the operations of a
conventional dryer and a conventional grinder. So it
makes sense to compare it to such a dryer and grinder
combination.
Because some of the water removal is due to mechanical forces,
the KDS Micronex™ uses far LESS energy to dry than conventional
dryers. Such dryers absorb 3550 to 9000 kJ of heat to remove
one kg of water, i.e., 1700 to 4000 BTUs of heat per pound
of water removed. In contrast, the KDS needs only 1200 to
3000 kJ of electrical energy to remove one kg of water, i.e.,
0.15 - 0.384 kWhr per pound of water of water removed. Assuming
that conventional dryers use natural gas (Cost = US$11 per
million BTUs, in Sep 2005), the drying energy cost is 1.9 -
4.4 cents per pound of water removed. Assuming that electricity
costs US$0.06 per kWhr (in Sep 2005), the cost to dry in the
KDS is 0.9 - 2.3 cents per pound of water removed. Thus, it
is cheaper to dry using the KDS. While the cost advantage
of the KDS does depend on the relative prices of natural gas
and electricity, it must be pointed out that electricity prices
are much more stable than natural gas or oil prices.
The KDS uses no additional energy for grinding. The
above exposition shows that the KDS is more efficient than a
regular dryer, so it goes without saying that it uses less
energy than a dryer-grinder combination.
Power Requirements as a pure Grinder
The power requirements for the KDS as a pure grinder that does
not need to do much drying are comparable to conventional ball
or hammer mills.
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5: Is the product is pathogen-free
and odor-free?
Manures and other waste products can be processed by the
KDS machine to be free of salmonella, e-coli, and other coliforms
and to virtually eliminate all other pathogens.
The air temperatures in the machine can reach 90 deg C (195
deg F), and the particle temperatures may briefly be much
higher than that, due to kinetic heating during collisions.
These high temperatures kill pathogens. The immense centrifugal
accelerations also cause cell walls to rupture and die.
Smell from substances like paper sludge and manures is significantly
reduced after processing due to the reduced moisture content
and reduced microbial activity.
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6: What is the production rate of
the machine?
The production rate depends on the type of material, initial
moisture content and feed size. The greater the moisture reduction
required, the lower the production rate. The smaller the feed
size, the higher the production rate. Production rates 3 to
4 tons per hour are obtained in the 250 Horsepower model.
Higher production rates are expected with newer KDS Micronex
models under development (see 14).
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7: How are the dryness and particle
size of the end product controlled?
The product moisture content depends on the initial moisture
content, feed rate, and classifier speed. The higher the classifier
speed, the finer and drier the end product.
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8: What product particle sizes can
be obtained?
The product particle size depends on the material characteristics
and the classifier speed. The higher the classifier speed,
the finer the product. Woody products will have a particle
size range of 250 microns to 2 mm (60 to 10 mesh). Other biomass
products will have a similar size range. Soft minerals, oyster
shells will have particle diameters ranging from less than
45 to 150 microns (325 to 100 mesh). Up to 15 % of the glass
powder made by the KDS Micronex™ can be finer than 1
micron and all of it will be less than 45 microns (325 mesh)
in size.
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9: What emissions come out of the
KDS machine? What noise levels?
The water removed from the material leaves the machine through
the vapor vent in the form of a fine mist and vapor. Air
emissions from most
substances, including those from broiler litter
and paper sludge, do not have any significant odors. However,
while processing some other materials, it may be deemed necessary
to use a scrubber to remove this mist and vapor.
The measured noise level is 87 dB at 2 meters (6.6 ft). Ear protection
is recommended.
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10: What is the operating cost of
one machine?
The power consumption of the machine is about 150 kW while
running at steady state at full capacity. Assuming an electricity
cost of US$0.06 per kW hr, it would cost $9/hour to run the
machine. Other costs will be maintenance costs and labor costs
(see 11, 12, and 13).
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11: What is the rate of wear of
the chains and other moving parts?
The strike mechanism (chains) wear rate depends on the material
being processed. For soft moist materials like chicken manure
or paper sludge, the chains last up to 40 hours. Abrasive
materials like glass will wear out the chains much quicker.
In such applications, blades made of anti-wear material will
be used.
Other moving parts like rubber paddles, bearings, belts, and
pulleys will last for tens of thousands of hours before needing
replacement.
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12: What are the maintenance costs?
It costs about US$12-15 to replace one set of chains (see
above). Replacing the chains takes only 5 to 10 minutes.
For most applications, chain replacement cost is less than
US$1 per hour. The total for other miscellaneous maintenance
costs associated with rubber paddles, bearings, belts and
pulleys are also less than US$1 per hour.
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13: What are the manpower requirements?
The KDS machine along with its feeding and product removal
systems can be fully automated using instrumentation and
Programmable Logic Controllers (PLC). Thus, it can be
fully integrated with an existing process. The overall
plant operator will need to only occasionally monitor the
operation of the KDS machine.
In a non-automated process, one machine operator and one assistant will suffice with
an optional third laborer depending on the plant configuration.
The machine operator needs no special skills or qualifications
beyond mechanical skill, familiarity with tools etc. The
duties of the assistant
and the laborer will include loading a hopper with the raw material
and removing the finished product coming out of the machine.
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14: Can FASC produce a larger machine
that could process more material, more quickly?
The KDS MF-777 is a larger version of the KDS 250S4 which
has a grinding chamber that is 34 % larger than that of the
KDS 250S4. Compared to the latter, the KDS MF-777
processes nearly 1.5 times more palm waste at a lower energy
consumption per ton of material. FASC also has other
designs for KDS machines that are larger than the 250S4 model,
which are being built now. The KDS S6 and S8 have
grinding chambers that are 38 % and 70 % larger, respectively,
than that of the KDS S4. The S8 can be fitted with a 500
hp motor whereas the S4 can have only a 250 hp motor.
Thus, the KDS 500S8 will have 2-3 times more production
capacity than the KDS 250S4.
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