Pulp Paper & Logistics
INDUSTRY NEWS 21 VALMET
Christian Schwartz
perspective and keep going. If we can improve a little every year, we will produce great results.” To think ‘outside the box’ is an
expression for being creative and finding new ways. This seems to be common practice at Mölndal Energi: “Today we look for entirely new opportunities. We have an old boiler that is not used much, and so far we’ve come up with 13 different alternatives for how to develop it. It’s exciting to think of what the future may bring.” Mölndal Energi ordered a study
operating season is a challenge because this is controlled by the climate and local weather conditions. Says Schwartz: “On warm days the output from the turbine is lower, which means that we have to lower the load on the boiler. The boiler performance at low loads therefore has a direct effect on how long our operating season is. When we chose the supplier for our new boiler we paid close attention to this because the better the performance is at low loads, the more electricity we can produce during spring, summer and autumn.
“We have also installed coolers
that we use on warm days. Our boiler has great performance at low loads, and together with the coolers we get a very long operating season, more than 7,100 hours a year. We only stop the plant during the two hottest months.” “In order for us to make
progress, many different organizations and lots of people have to contribute. First we did the easy upgrades – the ‘low- hanging fruit’ if you like – but after this things became more difficult. When this happens, you have to focus on the long-term
from Valmet to find ways to increase the energy output from its designed capacity of 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 per cent above the design capacity. Thomas Nordin, sales and
project manager at Valmet, comments on some of the important steps in the work: “The plant has to remain safe when the energy output increases, so I recommended getting an independent third party involved from the beginning. Consequently, we at Valmet, our customer Mölndal Energi and Inspecta were able to work together from the beginning. I think this made the work easier for all of us.” Increasing capacity is always a challenge. Thomas continues:
Thomas Nordin
“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. It’s professionally rewarding to get good results like this. It’s always nice.”
Mölndal Energi at a glance Swedish energy company Mölndal Energi is owned by the city of Mölndal. The company has a boiler plant, an electricity grid and a district heating network. It has 95,000 customers; generates 440 GWh of district heating per year, generates 124 GWh of its own electricity produced per year, and sells 834 GWh of electricity per year. More information from Mölndal
Energi at
www.molndalenergi.se. For information about Valmet’s input contact Magnus Fischer, Sales Manager, EMEA, Valmet. Tel: 46 (0) 3150 1000. Email: magnus.
fischer@valmet.com
July/August 2015
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