Maersk drillships have ultra-fast black out restarts

Fast restart time results from optimization of the turbocharger, jet assist system, control system and AVR (automatic voltage regulator)

NOVEMBER 14, 2014 — Four drillships under construction for Maersk Drilling at South Korean shipbuilder Samsung Heavy Industries will have main generator engines with a black-out start time of just 8.5 seconds. That compares with a standard starting time of 30-40 seconds.

The improvement has been achieved by an optimization of the turbocharger, jet assist system, control system and AVR (automatic voltage regulator) carried out at the request of Maersk Drilling, by MAN Diesel & Turbo and Doosan, who respectively designed and built the engines for the new drillships,

The fast start mode will only be activated during emergency situations, i.e. during a blackout, when the rig must be back up and running as fast as possible. The reason is that a floating rig is dependent on the power provided to its thrusters in order to stay in position, as well as to maintain critical drilling operations.

Without power to the thrusters, there is a risk that the rig will drift off its position, which can potentially give rise to huge impacts and the risk of damage to the subsea equipment (BOP and riser, etc.), including the risk of significant financial impacts for repairs, new equipment and lost day rates. The fast emergency start-up times have been obtained by optimizing and tuning the existing engine systems, i.e. the turbochargers, jet assist system, starting air system, governor control system and the AVR (Automatic Voltage Regulator) of the generator.

An optimization procedure of this kind has never previously been performed on this engine type; it was the Maersk Drilling project group which presented, required and drove the process of securing the improvement in engine performance in accordance with our requirements.

The result was achieved through several meetings and excellent cooperation between all parties involving both the engine designer MAN Diesel & Turbo in Germany, the licensee Doosan (which is building the engines), Samsung and ABB (generator manufacturer). Because this exercise had never been undertaken before, it took considerable effort to get the engines to reach this level of performance.

As a side note, says Maersk Drilling, it can be mentioned that the engines now meet the starting-time requirements for an emergency generator at a nuclear power plant. Furthermore, the engines’ optimum now matches the generator output. This has been achieved by de-rating the engines and introducing smaller turbochargers, which has improved the load step performance (the ability to take up load quickly), which will result in improved performance of the MMC (Multi Machine Control) mode during drilling operations. Further, this has optimized the fuel oil consumption during low-load operations and has resulted in a yearly fuel saving of about 5.3% compared with a standard engine set-up.