The Arthur Loibl GmbH has been awarded an order by an internationally operating German crane manufacturer to supply two laterally displaceable hopper cars. These include discharge conveyor and transfer chute with garland stations to the following quayside conveyor for a Danish coal-fired power plant in Skodstrup.
Via coupling rods the hopper cars are connected with a customer-supplied double jib level luffing crane.
Scandinavia is a strongly growing market setting high standards especially for environmental protection and is very conscious of dust and noise emissions as well as of the energy balance.
In order to minimize possible dust emissions for handling in this area where coal is fed into the hopper, both hopper cars are equipped with three-sided dust protection walls approximately 3m high with an approximate upper curve of 500mm as mechanical dust protection and a water atomizing system.
In order to reduce possible dust emissions when feeding on to the conveyor belt, the transfer to the longitudinal quayside conveyor has also been equipped with a fogging system.
Special single-component nozzles spray the water with a drop size distribution of 100–500μm.
The booster stations required for the fogging system, valves, valve unit with solenoid valve for atomizing start and stop as well as diaphragm valves for pressure setting are located in heated pump containers.
The hot-dip galvanized piping to the nozzles is protected against damage due to freezing by means of an insulation and heating.
The fourth water-side front wall of the hopper is designed as spillage flap and can be opened and closed via hydraulic cylinder.
The necessary hydraulic units are installed at the respective hopper car. A cover grid with a mesh size of 200 x 200mm retains larger grain sizes.
For noise emission reduction <94 dB(A) the hoppers are lined with wear-resistant and sound-absorbing rubber-steel sheet elements and the hopper corners with polyurethane steel sheet elements to minimize the product deposits.
Additionally, two pendulum-type vibrators on the two lateral faces of the hopper are used to remove possible coal residues. If necessary, these can be operated alternately and temporarily.
The hopper is monitored with a weighing system including
evaluation unit and if there is the danger that the material will pile up, the crane discharge is stopped.
Weighing electronics is integrated into the control system via Profibus.
For the operation in winter the hopper walls and the water atomizing system are provided with an insulation and are heated with a flexible resistance heating cable.
Furthermore the hoppers are equipped with the required stair accesses and maintenance platforms each.
Hopper discharge is made with a sturdy discharge conveyor, which is suitable for use in winter, of 1,600mm belt width and a centre distance of 12,000mm with upstream needle weir. The discharge conveyor is designed with rubberized pulleys, thick- layered rubber belt, inner and outer belt cleaners, closed bottom, corrugated steel sheet cover and all necessary monitoring and safety equipment, as well as a discharging chute with buffer idler
garlands and chute walls with wear-resistant and sound-absorbing rubber-steel sheet elements for sound emission reduction <94 dB(A).
The overall system is designed to be operated at ambient temperatures from –25°C to +40°C, with a possible air humidity being up to 100% due to direct vicinity of the water.
Power supply to the hopper cars is made through the cranes and the speeds of the discharge conveyors are controlled by frequency converter included in the scope of delivery.
The electrical switching and control system to operate the hopper cars, as well as the fogging system, hydraulic system, heating system and lighting system were included in the scope of delivery.
For handling of other bulk material, such as wood pellets, the version of the hopper cars detailed above can alternatively be equipped with an additional dedusting system. In this case the cover grids of the hopper opening would be replaced by a Flex-Flap System and to reduce emissions a dedusting system with integrated filters be used.
Initial start-up of the sturdy hopper cars combined with the harbour cranes took place in March 2010 and proved their suitability for use in harbours.