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My generation

Published:  01 April, 2014

Opra’s CEO, Fredrik Mowill, gives ODEE his take on some of the current key issues surrounding generator technology for offshore oil and gas platforms, and also considers some likely future trends that suppliers, specifiers and users should be aware of.

For the ready supply of power on offshore applications, generators are naturally a critical tool. So what are the key functionality and service specifications that users and specifiers should look for when sourcing a solution that is the perfect fit for their requirements? Opra’s CEO, Fredrik Mowill, considers that one of the first points to consider is the type of fuel options; the primary ones being natural gas or diesel. “Although a number of users run on diesel for their generators on offshore platforms, diesel is mainly used as a backup option when natural gas is available – this is because gas is the cheaper option on the whole,” he said. “Alternatively, if the user doesn’t have access to natural gas during certain periods of operation on the platform, a generator with dual-fuel capability can provide with a lot of flexibility. The OP16 gas turbine, for example, can run on either diesel or natural gas.”

Fuel quality

Continuing the fuel discussion, is fuel quality an issue? “If users run a generator on gas from the oil well and if this is clean natural gas usage, the whole operation will normally be straightforward, efficient and cost-effective,” said Mowill. “If, however, lower quality gas is used it’s important to bear in mind that the generator should have the capability to run on a wide range of fuel specifications.” Mowill added that this is another advantage of the OP16 system. And with regard to diesel, Mowill points out that there is not much of quality issue to consider. This, he explains, is because it will essentially be an industrial grade of diesel fuel that is fit for purpose from the outset.

Space and weight requirements

Another important aspect to consider when sourcing a generator, according to Mowill, is how much space is available on the platform. “On offshore applications space can be very limited, so sourcing a highly compact generator can be critical,” he said. Also, especially for fixed platforms, weight can be an important issue. According to Mowill, OP16 can fit most space and weight criteria in that it features an all-radial design, single-stage compressor and single-stage turbine, making the unit both light and compact.

Maximising uptime

In the case of continuous duty applications the platform is dependent on the power produced by the turbine, and to have high reliability and availability is of course critical. Therefore, Mowill stresses that the need for low maintenance should also be seen as a comparably important issue. “It is advisable that the user’s choice of generator only requires around one inspection per year in order to maximise uptime,” he said, adding that Opra’s own generators require one annual inspection, during which time the turbine will be out of service for a couple of days. During this period the company inspects it for any potential future issues, and changes the filters. Mowill explained that Opra generators then require a major overhaul after five years of operation, which amounts to around 40,000 hours of operation.

Mowill also recommends that users of offshore generators have the option of a long-term service agreement covering, for example, a 10-year period. This, he says, should ideally cover everything, including unscheduled downtime, for a fixed rate. “Many of our own customers opt to have this level of service,” he said. “We as the supplier then take on total responsibility for the equipment, setting out to ensure that the engine continues to run efficiently at all times.”

Training

Mowill also pointed out that Opra offers training programmes which most of its offshore clients take advantage of. “These courses explain to operators some of the most effective preventive maintenance techniques that are currently available,” he said, adding that the courses also give operators the opportunity to become familiar with the equipment and, in many cases, reach what he calls ‘advanced’ or ‘expert’ standard. “In general, the courses help operators to take the best care of the equipment and follow the recommended maintenance schedules,” said Mowill.

Monitoring

In terms of monitoring solutions for the effective running and checking of generators for offshore oil and gas applications, Mowill considers that what is expected from all manufacturers is that these have a remote monitoring capability. “It is almost a given today that you have online diagnostics and that you can monitor the equipment from the manufacturer’s facility,” he said. “We can supply monitoring systems, as do many of our competitors, whereby you can not only monitor remotely but also benefit from some diagnostics, generate a monthly report and be aware of any trending that’s on the data that you have collected. This type of functionality has become fairly common over the past five years or so, and indeed it’s reached a point now where it’s expected that you are able to do that. It’s a powerful tool because in the days before the Internet you were dependent on collecting data from the field and sometimes the operators recorded data that wouldn’t be sent back to you for analysis in an effective manner. Today, you can monitor all relevant data online and it’s quite an easy process to pick up any negative trends, meaning you are then in a better position to deal with them preventively rather than reactively.”

Mowill added that monitoring and remote diagnostics systems currently available are normally linked to the PLC control system. “There are a number of recognised packages available and sometimes there are add-on modules to the standard PLC that take care of the remote monitoring,” he explained. “It’s essentially all about having the means to control the turbine, diagnose and monitor and trends or other issues, and have a data link so you are able to read all of that data remotely. With solutions that are available today, this is a fairly straightforward process.”

Rent or buy

And what of the rent or buy option? “Although many offshore companies – certainly the majors – don’t have any notable financial issues as such and therefore wouldn’t make a rent-or-buy decision based predominantly on cost per se – rental can be more prevalent when users are planning to operate a platform for a shorter period,” Mowill pointed out. “So I think in terms of offshore applications the rental option is normally considered more favourably if generator requirements are either uncertain or known to be needed over a relatively short timeframe. For instance, if users plan to operate a platform for only two years or if they think they will only have gas available for two years, after which period it will run out, then they might prefer to rent the generator.”

Future developments

As regards potential near-future design or technology enhancements in the world of generators for offshore use, Mowill observes one aspect that is becoming more and more important is lower emissions. “This will become increasingly critical over the next few years and will drive development towards lower-emission combustion systems,” he said. “This is an area where we spend a lot of resource. It’s particularly important for NOx. We already offer a low NOx option for our turbines, which is less than 25 ppm NOx, so we guarantee less than 25 parts in 1 million. However, in the future this will probably move to a single-digit NOx level, so we are very involved in pushing that level down even further both to remain competitive as a company and also to stay ahead of future regulation.”

According to Mowill, another aspect that will increasingly become a primary focus for generator suppliers is that of being able to supply generators that can run efficiently and reliably on a wide range of different quality fuels; in many cases with low calorific values. “Opra is already quite advanced in its technology as we have been aware of this growing requirement for some time,” he added.

Additionally, Mowill maintains that there will continue to be a drive towards ever higher levels of turbine efficiency regarding generator usage. “It’s all about continuous improvement,” he concluded.

About Opra Turbines

Opra was established in 1991 in Hengelo, the Netherlands, and develops, manufactures, markets and services power generation sets based on Opra’s advanced turbine technology.

Opra provides power generation sets in the 2 MW power range as single or multiple installations.

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