Figure 2: Coperion double boom vacuum ship unloader
How Should A State Of The Art Vacuum Ship Unloader Look Like? Introduction Coperion is a leading supplier of pneumatic vacuum ship unloaders for unloading of Alumina and Petcoke from seagoing vessels. In 2007 Coperion incorporated the Hartmann company, acquiring with it, the experience of more than 100 years in the field of pneumatic unloading. The design of the vacuum ship unloader will be adapted to the climatic conditions of the operation place. Coperion has proven to have the right technical solution with its references reaching from hot areas in the Middle East, to very cold areas in Canada. Coperion can adapt the unloading
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capacity of its vacuum ship unloader from 150 t/h up to 1.200 t/h. The capacity design is done considering a specified max. berthing time and/ or the capacity of already existing down stream conveying equipment. Single Or Double Boom The distinctive attribute of a vacuum ship unloader is the number of unloading nozzles and conveying pipes. Usually there are 1 or 2 pipes and each one is arranged on one boom. Hence there are single or double boom unloaders. A single boom design has its advantages in a minimum amount of equipment and a lighter steel structure due to one single point for the force introduction. The lower
MATERIALS HANDLING AND TRANSPORTATION
amount of equipments reduces the maintenance costs of a single boom compared to a double boom. (see fig.1) The double boom design is more flexible and the unloading process can also take place in two separate hatches. Another big advantage is the high availability of the system, due to the fact that the unloading can also take place with one boom in case of any technical break down of the other one. Also the resting process is faster with a double boom design and therefore reduces the berthing costs of the ship. (see fig.2) Conveying line The conveying line of the vacuum
ship unloader has various special equipments which will be described in the following part. A proper adjustment of the product fluidisation and the conveying air at the product pick-up point is necessary to achieve smooth product conveying. Coperion has designed a special suction nozzle with adjustable setpoints for the false air, ie. the air that will be aspirated in addition to the mixture of bulk material and air at the nozzle inlet. This leads to an optimized, stable and safe aspiration process at the nozzle inlet and consequently to a stable and reliable pneumatic conveying process in the pipe. The telescopic vertical suction pipe is needed to reduce the lifting height during lifting of the boom and to adapt the pipe length to the tide height of the ship. After the vertical suction pipe the 90° bend is needed to guide the product flow. On this 90° bend the product flow impacts directly and wears the lining of the bend. To ensure a high life time these bends are lined with basalt or ceramic. Another important feature after the 90° bend is a pipe prolongation with the same lining as used for the 90° bend to reduce the wear of the first part of the horizontal suction pipe where the product stream is still a strand on the pipe top. The horizontal pipe can be executed as a fixed or a telescopic pipe. Whereas the fixed pipe has less investment cost and less maintenance cost, the movable pipe is more flexible for positioning the vertical suction pipe in the hatch. Without a telecopic device at the horizontal pipe, often the entire ship unloader has to be moved for placing the suction nozzle in a desired position.
AWJ 2013
Figure 1: Coperion single boom vacuum ship unloader A highly efficient pre-separation of the bulk material from the conveying air is necessary in order to protect the filter bags of the vacuum filter and to extend the lifetime of the latter. Therefore, Coperion has designed a filter with a preseparation of bulk material and air. As a result Coperion can optionally use filter cartridges instead of filter bags, thus enabling downsizing of the filter housing. The Coperion filter specialists are continuously working to Improve the performance of the filter and to deliver to our customers the state-of-the-art technology or to update the existing filters. Coperion has two different systems for the airlock beneath the filter. Both airlocks are based on the rotary valve design, which assures continuous discharge. The first air lock system is the Coperion rotary belt discharger. The rotary belt discharger has belts for sealing the rotor and for minimizing wear on the housing of the rotary valve. This solution is a well proven and economically beneficial technology. (see fig.3) The second solution is the Coperion ceramic lined rotary valve. This valve has a ceramic lining in the housing and tungsten carbide welding on the tip ends of the rotor in order to have
a much higher wear resistance than the economic construction materials like mild steel or cast iron. This solution has a very long lifetime and is economical due to the savings achieved from lower maintenance costs. (see fig.4) For discharging the product from the rotary valve to the jetty conveyor Coperion offers different solutions depending on the bulk material. These solutions are: • Coperion Duroslide (Air gravity conveyor). This is the most economical solution for the conveying of Alumina, if the difference in height of the ship unloader and the Jetty belt conveyor allows the installation of a sloping air gravity conveying. • Belt conveyor. This is the most economical solution, if Petcoke and Alumina have to be conveyed. In addition, this technology allows the installation of a belt scale for controlling the total unloaded mass. • Through chain conveyor. The
through chain conveyor is a totally enclosed and robust system for the conveying of Petcoke and Alumina.
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To generate the vacuum in the conveying system Coperion uses its own rotary piston blower or a fan. Each of the two principles has its advantages in different application sizes. Two stage fans will normally be used in vacuum ship unloaders with high capacities (>300 t/h) in one conveying line. Fans have the advantage of low investment costs. Furthermore, the efficiency is higher in the nominal operating range. During the resting process the transported capacity of bulk decreases and the conveying velocity would increase if not adjusted accordingly. The conveying velocity has a direct impact on the wear aspect. In a fan application the air flow can be reduced easily with a flap. Below a conveying capacity of 300 t/h the rotary piston blower has proven to be the best technical and economical solution. (see fig.5) Steel structure Beside the process equipment in the pneumatic conveying line there are different mechanical aspects that make a Coperion vacuum ship unloader unique. The slewing mechanism for the boom can be located directly below the booms, so only the boom is slewing. Another solution is to locate the slewing mechanism under the filter housing, which means the entire upper part of the unloader including all equipment like filter, rotary valve and the rotary piston blower/fan are moving with the boom. The first solution applies for double boom vacuum ship unloaders and the second solution
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Figure 3: Coperion rotary belt discharger without cover will be used for single boom vacuum ship unloaders, with the aim to use the filter and the other equipments as a counterweight to the long and heavy boom. Then no additional counterweight is necessary and the gravity centre can be lowered as much as possible. In general it is necessary to reduce the steel weight to a minimum and to design the unloader to have the gravity centre as close to the ground as possible. One advantage of the lower gravity centre is the resistance against earthquake forces that have to be considered and that would lead to instability in case of a high gravity centre. The second advantage is the reduced cost of steel/steel assembly and the related costs for the grounding and rails. Another important point regarding the loads on the quay is the amount of the wheels and how they distribute the loads to the rail.
Figure 4: Ceramic rotary valve in a vacuum ship unloader Coperion is engaged in engineering studies and revamping projects of vacuum ship unloaders for example on the following items: • Exchange of the bogies • Boom exchange • Filter refurbishment • Exchange of the control system
The most convenient solution for the steel structure can only be provided with the choice of the best steel structure concept and the application of modern FEM design tehniques. Modernization, Refurbishment Beside new vacuum ship unloaders
MATERIALS HANDLING AND TRANSPORTATION
• Throughput increase Summary Before designing and installing a new ship unloader, many different parameters have to be considered, reaching from the environmental data (temperature, wind forces,
earthquake forces) to the individual requirements of the customer (max. loads on the jetty, unloading capacity, resting process). As shown, there are many technical solutions available for each part of the pneumatic unloading process, for the supporting steel structure and for the motion of the ship unloader. Only with the profound know-how of an experienced specialist like Coperion, that has available the entire range of technologies for each process step, it is possible to design the optimized technical and economical solution that fulfils the project and customer specific requirements.
Figure 5: Coperion rotary piston blower
Authors: Frank Speck (Head of Sales, Aluminium & Minerals Industry) and Bertram Bartsch (Sales Manager, Aluminium Industry)
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>>Why we enjoy an unloading challenge. Because time is money and this is also very true
when it comes to alumina and petcoke unloading. With our Vacuum Ship Unloader VSU, featuring leading-edge technology and our deep process know-how, we can guarantee short ship lay times and ensure gentle and reliable unloading of your product. That’s what we mean when we say „confidence through partnership“ . >>www.coperion.com > For unloading capacities up to 1.000 t/hr > Double or single boom technology
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