Oil recovery operations - Why choose steam?

In the ever expanding oil explorations and extractions outside the world’s coastlines the importance of a solid and functional emergency response system is constantly increasing.

Part of that challenge has been an important topic for the Parat Halvorsen R&D team for many years. If a disaster should happen and the crude oil emulsion is successfully salvaged by supply and service vessels before it can do damage to our coastlines it is important that the emulsion is kept sufficiently viscous to be transported for processing. To ensure this the simplest solution is to keep the emulsion heated thus avoiding that it settles and hardens in the storage tanks.

Limited space and low weight requirements are just some of the challenges when designing a stand-by system for an offshore supply vessel. Another very important factor is system integrity and longevity. Especially considering that this is a system we are designing with the rare hope that it may never come into operation. As the minimum requirements for thermal input to the emulsion is more than 1200kW this challenge has required us to use much of our 40 years experience in the marine boiler market to develop a solution that covers all the bases.

A completely segregated system is mainly out of the question as it both costly and requires a significant installation space. In addition a boiler system needs to be in frequent operation to ensure full functionality and a long operating time. Therefore the system should be integrated into the overall heating circuit of the vessel, thus incorporating the heat recovery from the main engines during normal operation. In other words you should be able to operate the closed loop boiler system continuously without needing to use any additional energy.

Now considering the abundance of different tank systems that are intended for crisis oil recovery operations, the heat input needs to very robust and also optimized for permanent installation in the tank if necessary. If you intend to install the system during mobilization only, you will also want as few insertion points in the tank as possible. As the emulsion has a potential low calorific value many solutions will require an additional agitator system or circulation pumps to ensure sufficient heat distribution in the medium.

By injecting steam through multiple nozzles in one lance we have developed a system that solves all previously mentioned issues in one. Steam injection ensures sufficient agitation and thermal input in the medium to avoid using any kind of additional mechanical system. The multi nozzle lance design allows for just one DN250 nozzle in the tank to cover the full 500KW heat input requirement. The robust design of the multi lance also allows for permanent installation is most storage tanks.

When combining the multi nozzle system with the need for a boiler integrated in the hot water circuit we have developed the PARAT MEL-C boiler. This patented system allows you to operate a steam boiler in hot water mode during normal operation. An optional by-pass stand-by heating coil gives you the necessary flexibility to run the onboard hotwater circuit when mobilized for Oil Recovery Operations even if heat recovery system is not generating sufficient heat. This system can also be delivered with an oil or gas-fired boiler if the vessel does not have sufficient power supply to run an electrical boiler.

It is also possible to run the boiler constantly in steam mode and install a two phase heat exchanger between the boiler and the heating circuit.