Customer case:

More energy from existing equipment at Mölndal Energi

Feb 15, 2018

A fifteen percent capacity increase and more operating hours with only minor investments – this is the achievement of the energy company Mölndal Energi. Part two of Mölndal’s strategy is plant availability. This indicates how much of the planned operating time the plant actually spends producing. “During our first operating season, we had 98.4 availability. This was a good start, but we have been able to improve on that. Last year we only had one outage of about one and a half hours. This gave us 99.96% – now that’s a very good number!”

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We realized that we should increase our capacity, so after the warranty period, we turned to Valmet for advice. We got good help and today we can run the boiler at 80 MWth, instead of the 70 MWth that we had in the contract. That’s 15% more production every hour we run at maximum capacity. I always say that there might be another MW or so in there, so let’s see what happens next.”
Christian Schwartz, Mölndal Energi CEO

Summary

Location

Mölndal, Sweden
Customer target

The goals of Mölndal Energi are to be of good service to the society, efficiently satisfy the needs of its customers and minimize the burden on the environment. Mölndals Energi’s philosophy is to always try to get out more from their existing installation. always trying to improve. This moves the limits of what’s possible.
Solution

In 2009, Valmet supplied a new boiler to Mölndal Energi, starting up at 70 MWth. The same boiler has been upgraded and is now running at 80 MWth, or 15% above design capacity. Mölndal Energi ordered a study from Valmet to find ways to increase the energy output from its designed 70 MWth to as much as 77 MWth. Shortly afterwards, a second study was ordered with the aim of finding ways to increase energy output to 80 MWth – 15% above the designed capacity.

Each plant is unique because the boiler is built to match local demands. For example, the fuel mix, all the auxiliary systems and the turbine are chosen based on the design as well. It’s not always easy to increase the energy output.

In this case, we went through all the critical systems and described what steps could be taken. We calculated new flows for things like flue gas and steam, and also new operating parameters for air and oxygen. Some equipment also needed to be upgraded before we could start.
Results High plant availability, increasing output, higher capacity, longer operating season
Keywords Energy production, rebuilds, services, studies, capacity, availability, plant availability, strategy, mölndal energi, BFB, CFB, flue gas and steam calculations

Technical data

Mölndal Energi is a Swedish energy company owned by the city of Mölndal. The company has a boiler plant, an electricity grid and a district heating network. 
  • 95 000 customers 
  • 440 GWh of district heating per year 
  • 124 GWh of own electricity produced per year 
  • 834 GWh of electricity sold per year
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