BKK Varme: steam turbine automation retrofit increases reliability

Environmentally friendly energy is important to BKK Varme. Its main activities are the production, sales and transmission of electricity. An investment in new steam turbine automation has contributed to reliable district heat deliveries in the Rådalen region.

Good cooperation in Norway continues

BKK Varme owns the district heating system in Rådalen. The turbine and the heating plant are run by BIR Avfallsenergi, one of Norway’s leading waste management companies. The plant already has Valmet’s automation systems in use on waste incineration lines 1 and 2. It also has a service agreement with Valmet.

The good cooperation among BKK Varme, BIR Avfallsenergi and Valmet continues. Recently, the control system for a steam turbine and generator line 1 has been replaced. “For flexible operation, one user interface is important to BIR Avfallsenergi,” says Stig Högholm, Maintenance Engineer.

Old PLC logic replaced

The existing ABB extraction-back pressure turbine with 11 MWe had been installed in 1999. It is used in the incineration plant to produce steam from waste materials. In 2014, a new automation solution for the steam turbine and generator line replaced the old PLC system, which had reached the end of its lifetime. All turbine controls, protection, limiters and auxiliary system were integrated into the existing Valmet DNA automation system, and the entire operation is now run from the same control room.

“The old monitoring and control system from 1999 was outdated. There was some uncertainty regarding the availability of spare parts and expertise in the event of a breakdown. This might have led to loss of production,” explains Torkjell Tolo, from BKK Varme who is responsible for the site.

Valmet’s wide steam automation solution

Valmet’s delivery scope included an operator interface, a redundant Valmet ACN process station for turbine control, turbine protection 2/3 voting with three separate ACN MR compact controllers, overspeed protection, new speed sensors for field instruments and an operator panel for local operation by the turbine. In addition, new generator excitation, protection and synchronization have been installed.

“There are certain benefits of having one common control system at the plant. We wanted more advanced automatic functions – and indeed got them. The operators are familiar with the automation system. For all of us, it is definitely easier to get an overview of the whole process,” says Torkjell Tolo.

Seamless coordination throughout the plant

The open platform as well as the control and protection, which are integrated into one system, mean more precise information at the plant. Stig Högholm sees the benefits concretely in his work. “Now we can thoroughly analyze the reasons for the possible faults. There is more information for daily decision-making, and we can react sooner. What’s more, it is very positive for us that plant availability has increased.”

Valmet DNA Steam Automation offers redundancy and gives control of the turbine functionality. The high-speed process controllers use a temperature-dependent starting program with a quick run through resonance frequency bands.

District heating – an environmentally sound choice

For BKK Varme, the production of renewable district heating is important. Heated water is transferred to the district heat pipe network and then taken further to the consumers. The system requires flexible technology to adapt to the changing situations in heat distribution.

Torkjell Tolo emphasizes that many operations are now simplified, such as startup and sequences. “We can start the turbine if we need energy for district heating and stop when the need is lower. The turbine can be started quicker,” he says.

Project targets met

A well-planned project and quick startup are essential in a steam turbine project. When time schedules are respected and followed, the set objectives can be achieved and risks minimized. Just as in this particular retrofit project.

Stig Högholm explains: “I have to admit that the installation was well planned and on time. Sometimes, the start-up time can be chaotic, but we did not have any problems in this project. I’m proud to say that our expectations have been met: reliable turbine operation and quicker starts and stops.”

Both gentlemen emphasize that the cooperation with Valmet has been good. Now, after the completion of the project, Henri Hell, Service Technician from Valmet, is the main contact person for the plant. He continues the high-quality support in serving customers.

More information: 

Johan Musch

johan.musch at valmet.com