New chimney stack top for the RZR Herten waste incineration power station:

The challenge of working at a height of 100 metres

The RZR Herten waste incineration power station is considered as a classic example of efficient disposal and being of exemplary technology. At the start of the year GBT supplied another technical showpiece - At a height of 100 metres and under quite difficult conditions they put on a new stack outlet top.

Every year, around 650 000 tonnes of domestic, trade and industrial waste is burnt in the RZR Herten incineration power station. A significant contribution to a positive CO2 balance. This is because the operation of the waste power plant saves immense amounts of fossil fuels and therefore relieves the climate and environment.

By working sustainably on landfill sites, in the recycling industry, logistics and in the RZR Herten plant, AGR saves around 261,000 tonnes of so-called CO2 equivalent. This is equivalent to the "cleaning power of" a mixed forest area of the size of at least 36 000 football fields.

Put into operation in 1982, the RZR Herten waste incineration power station is continually updated according to the latest technical developments.

Six incineration lines, modern flue gas scrubbing

The Herten site consists of six incineration lines in total, which ensure an optimal thermal treatment of waste.

The flue gas scrubber at RZR Herten with its sophisticated filter system is a very good example of the latest incineration technology. It makes sure that the waste power plant's emission is normally only less than ten percent of the legal limit.

Also, the basis for this is not least because of the operator's really finely-meshed control and revision management. Here the requirements are literally speaking set exceptionally high.

For example, when considering both the 100 metre high power plant stacks.

Even though the use of new technical materials and an optimised operation of the incineration lines have permitted the interval times between chimney stack inspections to be greatly increased, RZR carries out an inspection of the vents every 18 months. Care and responsibility, pays off. For example in the form of sufficient planning leeway for pending strengthening measures.

In summer 2012, an examination of the stack outlet tops on the stack at two incineration lines showed a need for action well in advance. After over 20 years of reliable operation, one of the two steel stack outlet tops was now soon ready for replacement. Not an easy job.

After all, in this case it depends upon a huge amount of weight – over a tonne of steel to be exact. And a great height: over 100 metres above ground. A job for specialists, no problem at all!

100 metres: highest demands on material and technology

In the neighbouring town of Marl, RZR Herten found the headquarters of the German company GBT Bücolit GmbH. The GBT group is one of the largest German specialists in plant construction, renovation, optimisation, steel plant equipment and coating technology. With more than 300 employees it is active worldwide, including in the USA, China and India.

GBT, as a developer of many high resistance coating materials that are specially designed for flue gas scrubbing - and waste incineration plants, also has the necessary material technology expertise – a decisive criteria for those held accountable at the operating company AGR. Because their area of work requires specialist know-how.

The flue gas scrubbing system technology used in power station and waste incineration plants is based primarily on the principle of wet scrubbing. It creates specific corrosive environment conditions in process plants and flue gas ducts.

As a result of different plant designs and various modes of operation, practically every flue gas cleaning plant has its own chemical, thermal and mechanical Ioad-profile. This includes the system at the incineration power plant in Herten.

Selection procedure: The right coating system

For the coating of new stack tops that are still needing to be built and put on, GBT engineers, together with the customer decide the choice of system from a wide range of coating methods - for the BÜCOLIT V47-36 system, a Novolac vinyl ester resin reinforced with ECR glass matting.

BÜCOLIT V47-36 shows very good characteristic property values against thermal and mechanical loading and chemicals. It also has an excellent diffusion resistance. The coating is temperature resistance up to 180 °C, in some cases even up to 200 °C.

BÜCOLIT coating systems can be matched exactly to suit the different conditions they will be exposed to when in use. In this case for example, at a height of 100 metre above RZR Herten.

However, first of all the object to be coated needed to be created. This job required the manufacture of an absolutely identical "clone" of the long-serving steel outlet top. It was made in the HAW Linings GmbH works in Bornum, at the edge of the Harz region of Germany.

With the addition of HAW Linings GmbH, in Bornum am Harz, the GBT group has brought the inventor of the industrial rubber lining into its ranks. Simultaneously it belongs to the leading German specialists in steelwork and plant equipment construction. They make steel components such as plant equipment, pressure vessels, piping and accessories. This includes the new stack outlet tops at the incineration power plant in Herten.

Planning, project work, manufacture, coating, logistics and assembly: It was a positive synergy of these within the GBT group, which convinced AGR decision makers. This is because they could assume that the complete project would be technologically from one source and smoothly implemented, as well as planned and organised without delays. Come what may...

Surprising challenges

First of all, things didn't go to plan as they should have done: The long serving outlet top really clung on to its usual seating. Due to having been in it's airy, high up position over the decades; the top had "grown" into the counter flange and the connecting bolts inextricably bonded and couldn't be freed. There was only one solution to the problem: To separate the top, including flange, from a steel ring fitted adjacent to the stack wall. A significantly greater amount of work, which in no way should affect the original schedule.

There was also an additional challenge: Workers and materials needed to be transported 100 metres up the inside of the stack flue. This showed what experience can achieve: Within a few hours, the GBT special team carried out project planning and installed a transportation device with basket and winch. Up to 93 metres. Then the free space narrowed to only 1.60 metres in diameter – to little for the hoisting cage. About another seven metres were needed to bridge the distance to the workplace at the internal steel ring. This was achieved by installing scaffolding, which reached just below the steel ring that had to be separated from the old outlet top. It was then successfully carried out, costing only a little extra time.

At the same time, another GBT team had not a minute extra. Unplanned, they had to remove and replace an old counter flange by making a new one overnight. It needed to be directly fixed to the new stack outlet top and to be welded with it to the steel ring of the vent – i.e. in the position of the previously removed outlet pipe. GBT also mastered this challenge and delivered on time, on Monday in Januay 2014 to RZR Herten. The last act of this great drama: Putting on the outlet top at a dizzying height using a heavy-duty crane.

The precision placing took place here, 100 metres above the ground and with it the timely completion of a surprisingly challenging project.

Sustainability at the highest level

A good 30 years must now pass until this outlet top will need such attention again. So long will it resist wind and weather with its elaborate coating of high value P265GH steel. Completely designed to be sustainable – as for everything at the pioneering waste incineration power plant RZR in Herten.