Ejector technology for the shipbuilding industry
With more than 150 years of experience in the field of ejector technology, Körting Hannover supplies highly efficient and reliable solutions for the shipbuilding industry. Körting ejectors are used in a broad variety of shipbuilding applications wherever low investment costs, simplicity in design, maintenance-free operation and reliability are important.
How it works
The functionality of water jet bilge ejectors is solely based on fluid dynamics. Sea water from the ships own firefighting or ballast system is introduced under pressure into the motive connection of the ejector. The motive nozzle converts the static pressure into high velocity. As a result a defined low pressure section is formed downstream of the motive nozzle. The suction flow can be sucked in through the suction connections. Motive and suction flow intermix at the inlet of the mixing passage by means of impulse exchange. Subsequently the velocity of the mixed flow decelerates in the diffuser. The kinetic energy of the mixed flow is converted into static pressure at the outlet of the ejector again.
Drawn to a curve the velocity and pressure gradient along an ejector would be almost contrary. That means that an increase of the flow velocity inside will result in a decrease of the system pressure and vice versa. The velocity gradient inside an ejector from red (high velocity) to green (low velocity) is illustrated in the figure above. This abstract may give you an idea of the functionality of an ejector. However, the efficiency is always hidden in the detail. Only a customised design for the particular field of application affords the opportunity to save costs and energy.
Choice of material quality and high material quality standard
Our ejectors are made of high quality cast bronze materials (CC480K/CC483K) which are fully resistant to the chemical attack of sea water. Moreover these materials provide highest strength characteristics with low weight. However, in case of special requirements we can supply special designs in any other material quality.
The outstanding properties of these materials are also recorded by several shock and vibration tests and even blasting tests which have been carried out for military projects.
Design, R&D and manufacturing in Hannover
Design, R&D and manufacturing of our ejectors are solely done at our plant at the headquarters in Hanover, Germany. Therefore, a close alliance between theory and practice is guaranteed. It enables us to realise even unconventional technical solutions within shortest time.
Comprehensive service on-site
Our agents abroad and our project engineers are at your disposal at any time:
- during tendering / project planning
- during design / manufacturing / inspection
- during order processing
- after-sales service
Recognised by all known shipping companies
Körting bilge ejectors have been strongly linked with the shipbuilding industry since 1871. The following ships are deemed to be our oldest references:
- The worldwide oldest paddle steamer, the “HJELEN”. She is registered in Silkeborg and has been in constant service since 1892.
- The worldwide oldest seagoing passenger ship with a coal-fired steam boiler, the steamship “SCHAARHÖRN”. She is registered in Hamburg and has been in constant service since 1908.
Project-related design
The individual design of our ejectors results in minimised energy consumption at maximum suction performance. Consequently our ejectors will be designed for the most effective size. A customised bilge ejector means that the connecting pipe system can be ideally adapted to also reduce costs in the environment of the bilge ejector which includes parts such as piping, valves, fittings and other.
Optional flange design
In order to facilitate the assembly our standard ejectors are fitted with loose flanges. The counter flanges on the part of the pipe system do not have to be adjusted. The flange dimensions can be drilled according to EN, ASME, JIS, VG or any other flange standard.
Optional connection types
Our extensive unit assembly system enables us to adjust our ejectors in any required way. Among others our product range includes thread connections, hose couplings like Storz, Guillmin, etc. or straight pipe ends for quick couplings like Straub-Grip, Norma, etc.
Extensive documentation
Our documentation includes detailed operating instructions, technical specifications, performance curves, assembly drawings as well as work‘s specific test reports. Furthermore any special requirement by the shipyard or a certrification body can be taken into consideration.
Extensive stock
A sophisticated unit assembly system ensures longterm delivery service for all of our ejectors. To that effect our extensive supplies of spare parts enables shortest possible delivery times for all spares.
Final inspections
After completion all of our ejectors are subjected to an extensive final inspection, including general visual examination, dimensional checking as well as hydrostatic pressure testing. At the customer´s request performance tests of the actual operating conditions or recordings of special characteristic curves and various other tests can be performed before shipping takes place. If required all tests and examinations can be carried out under survey of any official authority or classification society.
Classification
Our ejectors are built in order to fulfil the specific requirements of the shipbuilding industry. This of course includes full compliance with the rules and regulations of all recognized classification societies like GL, DNV, BV, LR, ABS, RMRS, KR, and others.
Let’s have a closer look at the main area where ejectors are used in shipbuilding. Bilge ejectors are fluidic devices without mechanical drives, dynamic gaskets or any moving parts. Therefore, they are not subjected to mechanical wear, require no maintenance and dry running isn’t possible. Even an operation free of cavitation can be ensured if a design is project related. The functionality of selfpriming bilge ejectors is solely based on fluid dynamics, driven by water supplied by the mechanical pumps from the ship’s own system. In order to achieve optimum efficiency, the design of a bilge ejector should always be based on the performance data at the design point. The effective pressure data in relation to the connections must be taken into consideration.
How to avoid mistakes when designing bilge ejectors
A frequent mistake in technical specifications is to treat bilge ejectors in the same way as mechanical pumps. This ignores the fact that the behaviour of the performance curves of bilge ejectors and mechanical pumps is totally different. The design of an ejector always depends on the motive pressure related to the suction pressure and the discharge pressure. Nevertheless, you will find a number of vendors dealing with ejectors by catalogue. Therefore, you need to ensure you receive a quote for bilge ejectors with a constant total manometric head only.
Lower the operating costs
The standardisation of bilge ejectors has an adverse affect and results in a loss of efficiency. On the other hand, detailed planning at an early stage leads to lower investment and operating costs. However, when selecting a bilge ejector the necessary drive energy and consequently the right mechanical pump should be taken into consideration. The wrong choice in this context, based on the pure investment costs only, could lead to higher operating expenses during the whole life time.
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