Authorship: Li Yimin
from Bulk-Onweb issue 2017-9-26
Transmiting Capacity of Bucket Wheel Stacker and Reclaimer
(Bucket Wheel Stacker Reclaimer of Transmission Capacity)
Li
Yimin, In The second session of the china Association of Science Annual
Meeting Satellite Conference of youth ,Liaoning province Second Youth Annual
Conference Liaoning Provice ,China ,1995
Abstract: The transmission capacity of bucket wheel stacker and reclaimer has
not been defined for many years. However, the mathematic deduction method is
used in this paper to conclude three concepts of the capacity of bucket wheel
stacker and reclaimer in China, i.e. “maximum capacity”, “rated capacity” and
“average capacity”, thus to provide customers and manufacturers an uniform
concept for selecting products and making design and also to make it convenient
for communication between clients and manufacturers. It may help to avoid huge
economic loss. The reclaiming and stacking capacities are analyzed and explained
in details in this paper.
Along with the development of modern technology and enhancement of industrial
level, as key bulk material handling machines of high efficiency, the stacker
and reclaimer are widely utilized at large stockyards of port, power plant,
mine, metallurgical plant and building material suppliers. Due to continuous
advanced technology import from abroad and gradually raising of automation
level, the conveying capacity of stacker and reclaimer is tend to be measured
via metering device and the requirement on truck and ship loading time and
tonnage demanded by material handling department is becoming more rigid.
Therefore, it is critical for the machine designer, manufacturer and client to
establish a definite concept of conveying capacity, thus to ensure the stacker
and reclaimer and the bulk material conveying system can operate normally under
appropriate parameters and to avoid machine fault and unnecessary economic loss
due to improper parameters.
1.
Types of transmission capacity
At
present, the following designations are used to define the transmission capacity
of stacker and reclaimer by our domestic manufacturers and clients.
a.
Productive capacity (productivity); b. Rated capacity; c. Average capacity; d.
Maximum capacity; e. Theoretical capacity; f. Guaranteed capacity; g. Nominal
capacity; h. Titular capacity.
The
capacities mentioned above are of different value and different concept and
definition, which make it difficult for design and selection of systems.
Therefore, it becomes necessary to specify a uniform definition of capacity so
as to diminish design and selection faults. These eight designations of capacity
can be concluded to the following three:
1.1
Max. capacity
1.2
Rated capacity
1.3
Average capacity
The
“Productive capacity” among the above eight designations is cancelled due to its
uncertainty. The “Theoretical capacity” is deemed to be maximum capacity. The
“Nominal capacity” and “Titular capacity” are deemed to be rated capacity. The
“Guaranteed capacity” is deemed to be average capacity.
2.
Stacking capacity of stacker or stacker cum
reclaimer in operation
The
stacking process of stacker or stacker cum reclaimer is to deliver the material
from ground conveyor to stock yard. Therefore, the transmission capacity of
onboard belt conveyor shall be consistent with the ground conveyor. Such
transmission capacity can be noted as maximum capacity or rated capacity.
Maximum
capacity – means the maximum throughput of material flow on the belt conveyor,
which is also the throughput necessary to guarantee that the rated capacity is
reached.
Rated
capacity – means the throughput of material flow on belt conveyor when it is in
normal operation, which can be calculated by following formula:
QBR=KB·QBM
…… (1)
Wherein
the QBR
represents rated capacity; QBM represents maximum capacity (t/h); and
the KB indicates the throughput ratio of belt conveyor, KB=0.9
normally.
The
relationship between rated capacity and maximum capacity as shown above is
determined to ensure no material spill or blockage will happen to onboard belt
conveyor when the material flow of ground conveyor exceeds its rated capacity,
thus to guarantee normal operation of stacking work. Generally only the rated
capacity is required to be marked. The maximum capacity of onboard belt conveyor
should be larger than or equal to maximum capacity of ground conveyor. The
maximum capacity can be indicated by following formula:
QBM
= A·V·γ·3600(t/h) …… (2)
Wherein
A represents maximum material cross section on onboard belt conveyor (m2);
V represents belt speed (m/s); γ represents bulk material density (t/m3).
3.
Reclaiming capacity of reclaimer or stacker
cum reclaimer in operation
The
reclaiming process of reclaimer or stacker cum reclaimer is to reclaim the bulk
materials via bucket wheel onto onboard belt conveyor and then deliver the
materials to ground conveyor. The material flow on the machine in operation will
be variable, depending on reclaiming process, machine type, control mode, etc.
Therefore, the reclaiming capacity is related to these factors.
3.1
Maximum capacity
The
maximum capacity means the maximum ability of bucket wheel exerted when it is
excavating materials. It is also the necessary ability to ensure its rated
capacity. It can be indicated by following formula:
QRM
= 60I·n·N·γ(t/h) …… (3)
Wherein
QRM
represents maximum capacity (t/h); and I represents cubage of one bucket (m3);
and n represents bucket wheel rotating speed (r/min.); N represents number of
buckets; γ represents material density (t/m3).
The
maximum capacity is the basis for design of bucket cubage, bucket wheel rotating
speed, number of buckets, and maximum throughput of both onboard belt conveyor
and ground belt conveyor. For actual system design, the maximum capacity of
ground conveyor shall be larger than or equal to the maximum capacity of stacker
cum reclaimer or reclaimer in operation. The maximum capacity is unrelated with
machine type, control mode and operating method.
3.2
Rated capacity
The
rated capacity is the titular or nominal throughput of the bucket wheel stacker
cum reclaimer or reclaimer in operation. It represents the excavating efficiency
of the bucket wheel itself and the reclaiming ability when the machine is in
normal operation. It is unrelated with machine type, control mode and operating
method.
The
relationship between rated capacity and maximum capacity is as shown in
following formula:
QRR=KR·QRM
(t/h) ……
(4)
Wherein
QRR
represents rated capacity (t/h); QRM represents maximum capacity
(t/h); and KR indicates the excavating efficiency of bucket wheel, KR=0.9
normally.
3.3
Average capacity
The
average capacity means the average reclaiming rate or reclaimed tonnage per hour
that is achieved when the reclaimer or stacker cum reclaimer is operated by the
operator as per specified procedure and method to continuously work on a
standard-shaped stockpile as specified for a certain period of time (normally 4
hours or more). It can be indicated as following formula:
QUOTE
(t/h)
…… (5)
Wherein
QUOTE
represents
average reclaiming capacity; QUOTE
means
total time for determining the average reclaiming capacity; QUOTE
represents
the function of instant reclaiming capacity and time.
The
average reclaiming capacity of the semi-automatic controlled machine with
slewing speed regulation in accordance with secant function is as follows:
QRA
= KA·QRR (t/h) ……
(5)
Wherein
KA
represents the average reclaiming coefficient and normally KA = 0.7～0.8;
QRR represents the rated reclaiming capacity.
The
average reclaiming capacity is related to profile of stockpile, type of machine,
way of speed regulation, operation mode etc. Both the client and design
department put emphasis on this parameter since it will directly affect the
adaption of system. No more details are discussed here due to limited length of
this paper.
4.
Marking of transmission capacity of stacker
and reclaimer in technical documentation
4.1
Stacking performance
The
stacking capacity is normally marked with two parameters, i.e. maximum stacking
capacity and rated stacking capacity. If only one is required, the rated
stacking capacity shall be marked. The stacking capacity shall be marked on
nameplate or in the designation of machine.
4.2
Reclaiming performance
The
reclaiming capacity is normally marked with three parameters, i.e. maximum
reclaiming capacity, rated reclaiming capacity and average reclaiming capacity.
If only two are required, the rated reclaiming capacity and average reclaiming
capacity shall be marked. And if it is agreed by supplier and client, the rated
reclaiming capacity can be marked only. The reclaiming capacity shall be marked
on the nameplate or in designation of machine.
5.
Conclusion
There
has been no unified concept of stacking and reclaiming capacity of stacker and
reclaimer for many years, which makes it inconvenient to the user, designing
department as well as manufacturers. Especially the client who has never used or
knows a little about the machine in the past may be confused. And it tends to
cause contractual dispute at the time of final acceptance of project. It is
hopeful that this paper will help for the design and selection of these machines
by providing the concept of stacking and reclaiming capacity of stacker and
reclaimer. (Translated By Zhu hongguang)
斗轮堆取料机的输送能力
About The Author
Li Yimin ;
Professor Engineer ;
Graduated : DUT ->. Jan .1982;
Major : HOISTING AND CONVEYING MACHINERY ;
Metier: Designer For Bulk Machinery;
Main contribute for bulk machinery: He has embarked on design and
researsh Bulk Machinery for 34 years. Main contect include stacker
,reclaimer ,stacker / reclaimer , bridge type reclaimer , Blending
stacker ,Blending Reclaimer , gantry type reclaimer . He research the
main date for the bulk machinery especially.
He wrote many piece for the bulk machinery . some piece had released on
the journals in P . R . China , and had invented four item patents.
www.bulkcn.com 版权所有 屹立散料机械在线 大连重工2017-9-26
bulkcn@qq.com
bulktech@sohu.com
liyma@dhidcw.com
Tel： 0411-86852278
