CHP plant engine replacement in just 14 days

CHP plant engine replacement in just 14 days

SERCOO ENERGY, previously VG Diesel- und Gasmotoren Service GmbH, constructed a combined heat and power plant with two type MWM TCG 2016 V8 C generator sets for AES GmbH at the Rothmühle landfill site in Bergrheinfeld, and were commissioned to carry out full maintenance. After 48,000 operating hours, the E70 overhaul was now due. “Our task was to restore the client’s plant as quickly as possible. Since two identical generator sets were installed in one machine room, the challenge was to remove and reinstall the generator set to be overhauled as quickly as possible in order to keep the downtimes of the entire plant as short as possible”, explains Christoph Fitten, plant manager at SERCOO ENERGY GmbH. Both generator sets have engine circuit cooling and are coupled to the overall heat circuit. In order to avoid having to shut down both generator sets, the service team uncoupled the heat circuit first. “Our two fitters were able to remove the generator set in just one day, even though we had planned for two days. The spatial conditions required maintaining an overview and showing some ingenuity. As little of the generator set as possible was removed on site. It was then lifted with hydraulic jacks, pulled forward using heavy duty rollers and pulled out using the wheel loader provided by the client. As we were able to use technical equipment supplied by the client, no crane was necessary, which means we were able to save about €1,600.00”, Christoph Fitten explains and adds: “They have been our client for about seven years now. For removal, we were provided with two helpers who supported us energetically. The teamwork between the client and VG was excellent.”

Long block instead of short block: an overhaul option that pays off.

There are several options for overhauling a CHP plant:

One option is to completely overhaul the generator set at the client’s premises. However, this is not an ideal solution in terms of time and effort, as the plant would be at a standstill for 4 to 5 weeks.

The other option is to remove the generator set and then send it to our factory for overhaul. Downtimes of 3 weeks are common in this instance as well. A short block is ordered in exchange and there are still many spare parts with additional steps to be done by hand. That takes time. Furthermore, one has to bear in mind that the short block delivered in exchange has already been running for several operating hours - i.e. it is a spare part that has been overhauled in the manufacturer’s factory for renewed use.

Our favourite for the future:

For the overhaul of the AES GmbH generator set, the current SERCOO ENERGY used another option: namely, the removal of the generator set and the use of a long block. The removed generator set was transported to VG by truck, disassembled by the engine specialists, cleaned and supplemented with the long block. The generator was also overhauled on site at SERCOO ENERGY through the long-standing collaboration with Baumüller. The importance of professional collaboration partners with whom you can work hand-in-hand becomes clear again here.

“The usual procedure when overhauling the removed generator set is to use a short block, i.e. the lower part of the engine with camshaft etc. would be ordered from MWM Caterpillar Energy Solutions GmbH and then completed by us in Mengkofen. That takes about three weeks. By using a long block, we were able to reduce our workload to just 3 days”, says Christoph Fitten.

The other major advantage of using a long block is that the client receives a 12-month warranty on this new part. “The price difference was within reasonable limits, so we proposed this solution. Our suggestion convinced the client straight away. The saving comes from the reduced amount of time that we had to spend on the overhaul and the knowledge that, essentially, a new module was installed. Since our experience with this procedure was a positive one, we are planning to generally offer the overhaul with long block as an option. The price difference contrasts with the cost block of longer downtimes of conventional replacement options, meaning this overhaul option definitely pays off.

Thanks to the perfect collaboration and teamwork between the client’s employees and our fitters, both the removal and the installation of the generator set could be completed in just one day, despite the dismantling of the heating cabinet and plate heat exchanger as well as decoupling from the useful heat heating circuit.

By the way, the old engine was sent to MWM, where it would become a overhauled short block, i.e. a replacement engine without cylinders, pistons etc.. Currently, we already have the second generator set from AES GmbH with us for overhaul”, says Christoph Fitten, as he describes the advantages of using a long block for overhauling.

Chronological sequence of the generator set overhaul

• Phone call from client, Thursday 5 August
• Enquiry for a long block at MWM, Thursday 5 August
• Quote from MWM to us, Monday 9 August
• Quote from us to the client, Monday 9 August
• Order placed by the client, 10 August
• Long block ordered, 10 August
• Generator set removed, 12 August
• Loading onto truck at client’s premises, 13 August
• Generator set delivered to VG, Monday 16 August
• Disassembly-assembly at VG, 16-20 August (4.5 days)
• Overhauled module collected, 20 August
• Delivery to the client, 23 August
• Overhauled generator set installed, 23 and 24 August
• Commissioning: the generator set went back online in the evening of 25 August

CONCLUSION: At least 24 days would have been required for overhauling using a short block. By using the long block, we were able to save 10 days for the client, which in figures equates to 2,500 EUR / day = 25,000 EUR in total.