Rotating service partner for Nuon

Nuon generates electricity and heat on a large scale in the Netherlands. Rotating parts in the large units operated by Nuon for this form a crucial part of the operation. Overhaul is essential for these parts to keep functioning effectively. For a portion of this overhaul, Nuon has been using the services of Vos Rotating for many years.

Taco van Ketel is Rotation team leader in the Maintenance & Engineering Services division of Nuon. M&ES is the internal service partner of Power Heat & Services, a division which houses the activities Generation, Heat and Renewables. The latter branch, for example, focuses on wind and water energy.

“We (M&ES) support our internal customers, the managers of the various Nuon installations in the Netherlands.” Although Nuon uses fossil fuels such as gas, coal and blast-furnace gas for the generation of power, it is also looking for possibilities to use the fuels as cleanly as possible. “In Buggenum we have a coal gasification plant. Here the coal is converted into synthetic gas, which is then used in a gas turbine. This technique has far cleaner emissions than a conventional coal-fired power station. Once as this technique has been further optimised, a similar large-scale modern power station will be built: the Magnum power station at Eemshaven.”

Various clusters

The main task of Generation is the production of electricity. It is generated in various Nuon power stations and wind farms in the Netherlands. Cluster Amsterdam consists of several production units. Amsterdam has the Hemweg power station with two units, one gas-fired and one coal-fired, and Purmerend has a gas-fired unit that supplies heat to the city heat network.

Cluster Utrecht is mainly aimed at supplying electricity and district heating. This has to do with the demand in the region for heat and the construction of the system. At various Nuon power stations the surrounding areas also use the energy produced. This approach will eventually have the highest return.

The importance of overhauls

Taco van Ketel: “To generate electricity there are revolving parts in the installations; anything that rotates and on which forces are exerted in various ways must be stopped from time to time for inspection and maybe repairs. We partly perform this stop work together with Vos Rotating. The part played by Vos Rotating has for many years been the overhauling of various pumps, fans and gearboxes, as well as the supply of turbine mechanics during these stops. Vos Rotating performs this specialised work for us at the Nuon locations Amsterdam, Purmerend, Velsen, Diemen and Utrecht. Nuon distinguishes three workflows for the overhaul of rotating components in its units. The main components of rotating equipment are gas turbines, steam turbines, generators and fans. This overhaul work is performed under our management, in cooperation with, or fully contracted out by the original supplier (OEM) or executed by an equivalent party. Additionally, you have the flow of mainly special pumps, most of which go to the OEM for overhaul. In conclusion, there are a great number of regular pumps. For these it is less risky to look on the market for alternative suppliers, as both the necessary expertise and spare parts are more readily available. Within Nuon, Vos Rotating is the main supplier for that third flow. The lion’s share of the work is therefore done by Vos Rotating,” explains Taco van Ketel.

From A to Z

Richard Nansink works at Vos Rotating as Sales Manager Revision and Maintenance for the whole of the Netherlands: “In that capacity, me and my sales team are involved with Nuon. For the performance of overhauls on rotating parts we now work for all Nuon sites. With each approaching stop we receive a request, on the basis of which we provide a quotation. The execution of the stop is our speciality, not only in rotation engineering terms, but also in planning terms. On average a stop takes about three weeks and we do all of our work during this short period. Sometimes three engineers are required but at other times we need twelve engineers. We accurately modify our team to suit the demands of a specific stop. We also have regular contact with the OEMs regarding spare parts, know-how, tolerances and play. We then contact their Dutch representatives.”

Overhaul on the basis of prescribed maintenance inspections

The units are overhauled on the basis of prescribed maintenance inspections, but insight and experience also play a part. Taco van Ketel: “Planning an overhaul is an art. On one side are the prescribed regulations, on the other side is the subsequent loss if you continue production with the component or unit. If you look at rotating parts, the authorities are less prescribing when it comes to overhauls. On the steam side you are confronted with the Steam Equipment Supervision Service. From my perspective I also look strongly at the regulations for overhaul and repair prescribed by OEMs. All of these regulations and assessments are incorporated in a long-term plan, indicating when an interval expires and a unit needs an inspection. The aim is to perform as many inspections as possible in as little time as possible and to execute repairs with the aim to achieve problem-free operation until the next inspection.”

The huge importance of safety

Safety plays an important role during a stop. Richard Nansink: “While working with rotating parts anything can happen. You are working at great height with heavy parts. For every stop we prepare a task risk analysis based on the safety plan. Before a stop a PIM talk (Pre Inspection Meeting) is held between the foreman of Vos Rotating on site and the Nuon executive.” For the PIM not everybody involved during the stop needs to be present. Taco van Ketel: “In addition we have pre-work meetings prior to the work itself with all personnel involved, not only with Vos Rotating regarding overhaul and repair but also regarding safety and permits. The whole chain of events, including reports and delivery, is performed in close consultation with Vos Rotating. Examples are safety plans and hoisting plans.” Richard Nansink: “We report back on which repairs have been done and which spare parts have been replaced. Together we estimate very accurately in advance which risks may affect the processing time of a stop for a specific unit or part. We take our measures on the basis of this. Everything depends on a quick, safe and high-quality stop.”

The advantage of a country-wide network

Taco van Ketel: “During a stop there is frequent consultation between representatives of Nuon and Vos Rotating.
Vos Rotating is a versatile organisation. Within the field of rotating they can take on a lot, especially in the area of pumps for which we mainly engage Vos Rotating. They also stand out with many well-equipped sites in the Netherlands. There is always a Vos Rotating site in the vicinity of Nuon locations. The local presence leads to decisiveness and we appreciate that. After a stop has been performed, the start-up of a component is a shared responsibility of Nuon and Vos Rotating. Nuon performs a vibration analysis of an overhauled unit on the basis of a zero-value in addition to Vos Rotating performing its own analysis. As a result, the quality of the work performed is assessed together but independently.”

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