Understanding Tidal Turbine Sealing System Requirements to be Addressed at Upcoming International Tidal Energy Summit

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Hamburg-based Blohm + Voss Industries has developed and manufactured different sealing solutions for all types of marine drives. They will be outlining their sealant solutions for tidal turbines at the 3rd International Tidal Energy Summit, taking place in London on November 17-18th 2009.

Hamburg-based Blohm + Voss Industries has developed and manufactured different sealing solutions for all types of marine drives. The company believes its most valuable strengths lie in its in-depth knowledge about the working principles of LIP-type and FACE-type (mechanical) shaft seals.

Blohm + Voss' MD Martin Johannsmann, who is scheduled to speak at the 3rd International Tidal Energy Summit 2009 in London this year (November 17-18), spoke to Tidal Today about developing an environmentally benign tidal device with robust sealant solutions and other issues. Excerpts:

Tidal device developers work on several design phases, from scale model testing, numerical modelling to economic feasibility studies. What action or process do you recommend when analysing and developing the dynamic sealing system required for a tidal turbine?

Johannsmann: Since the shaft seal and its flawless performance is a crucial and sensitive component for propeller shaft drives, we - at BVI - are proud to announce that we have more than 60 years experience in manufacturing and developing marine shaft seals. So far, we have supplied more than 60,000 seals to the maritime industry.

BVI has been in the past, and still is today, one of the leading technology pioneers worldwide for new developments and special solutions for marine shaft seals. In our Hamburg based head-office, we have developed and manufactured many different sealing solutions for all types of marine drives including conventional drives, mechanical thrusters, electric driven POD's, water jets and special non-standard applications. These solutions can be found on naval and commercial vessels, submarines, smaller river-going vessels as well as oil-rigs and others.

One of our most valuable strengths lies in our in-depth knowledge about the working principles of LIP-type and FACE-type (mechanical) shaft seals which we both develop and manufacture in Hamburg, Germany. This strength enables us to develop tailor-made solutions for any out-of-the-ordinary application which is a great advantage for our customers as we do not limit our R&D efforts to only one type of sealing technology. Our customers often have unique requirements for our shaft seals. Regularly, we have to develop solutions for seals that operate in extreme or very unusual underwater conditions. For such cases we can, if necessary, combine the two main seal technologies, LIP - and FACE-type (mechanical seals), which gives us a distinct advantage over most of our competitors.

In terms of what action / process do we recommend when developing a dynamic sealing system for a tidal turbine - we propose R&D partnerships with the tidal device developers. As there are certain parameters like varying water-depths, rpm of the shaft, concentration and type of floating particles in the seawater etc. It is very important that these conditions are thoroughly evaluated. Only once all necessary parameters have been analysed, the right seal, based on FACE (mechanical) - or LIP-type technology or a combination of both, shall be selected. From our experience, this can be utilised best by forming the "R&D Partnership" between us and the customer.

Which according to you is the best approach to apply maritime experience to develop an environmentally benign tidal device with robust sealant solutions?

Johannsmann: BVI has introduced different environmentally safe seal solutions to the industry over the years which have been accredited as non-pollution seals by the main classification societies like Lloyds Register, USCG and others. Again, the possibility to form development partnership allows us to share our seal knowledge directly with the engineers of our customers and this helps both sides to understand why certain Lip - and Face-type technologies prevail over each other. In return, we learn what the tidal device manufacturer exactly requires and therefore can develop around his specific needs and requirements.

Our added value for the tidal device developer lies in our empirical knowledge and expertise for shaft seals. Ideally, a continuous knowledge exchange between the engineers from both companies needs to be established. In short, we need to learn the exact need of the customer in order to provide a tailor-made solution which will be developed in close conjunction with the customer.

As to the overall process of testing our seal performance, we follow the procedure to test our seals extensively in our in-house testing rigs before deploying it to the market. Thanks to our state-of-the-art testing facilities, we can simulate nearly any underwater condition for testing our seals. If necessary, we can extend our research to tests in the open sea.

Can you provide an insight into latest testing rigs with full tidal water simulations to analyse the durability, reliability and effectiveness of tidal turbine shaft seals?

Johannsmann: We have various testing rigs in our R&D department allowing us to simulate operating conditions for shaft diameters ranging from below 60 mm to over 1030 mm. Furthermore, we have a dedicated staff of well trained and experienced engineers in our R&D department that look after the development of our existing products and develop our future generation of seals.

As a technology leader, we believe it is our duty to invest in research and development of new sealing technologies and especially to continuously improve our existing sealant solutions. For example, the material composite used in elastomeric sealing rings for LIP-Seals or the sealing ring material for mechanical FACE-type Seals are under constant supervision and improvement to achieve best sealing results.

Over the years, a number of concerns have been raised about the environmental impacts of tidal devices. How important is it for the designing team working on a tidal device to evaluate the significance of various environmental considerations? Which is the best way to minimise environmental impacts?

Johannsmann: We, as shaft seal developers and manufacturers, have always been concerned with these important questions. On the one hand, we have to ensure that no substances or liquids escape through the seal and pollute the environment and on the other hand, we have to prevent water ingress to ensure smooth operation.

In the recent past, there have been various attempts and new developments to improve the overall reliability of shaft seals for vessels and submarines that could be applied to the tidal turbine industry. For example, we can combine LIP and FACE-type mechanical seals to achieve a better performance in even the harshest environments.

Generally, it is our philosophy to improve the durability and life-cycle costs of all our seals continuously.

Which according to you are the most crucial O&M issues facing tidal technologies and how should one go about finalising post-installation maintenance services?

Johannsmann: The most crucial O&M concern starts with the correct installation of the seals and involves the servicing of the seals at the right time and at the right place later. Also, forming partnerships must not stop at the R&D level.

We feel it is most important that the complete package from purchasing to life-time performance of the seal including price of the initial seal and the later occurring service costs need to be as transparent and as cost-effective as possible. Or in other words, there should be no sudden "cost surprises" for the operator of the tidal turbine.

3rd International Tidal Energy Summit 2009

Martin Johannsmann is scheduled to speak at the forthcoming 3rd International Tidal Energy Summit 2009 in London this year (November 17-18).

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or Contact: Abbie Badcock - on 44 (0)207 375 7581


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Abbie Badcock
Tidal Today
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