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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 = 0.70.8; 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.

 

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