Interview with a customer

GreenExergy took part in a renovation at Boliden Rönnskär

In connection with the big Boliden project with significant investments at Rönnskär GreenExergy contributed with extensive design work when the district heating facility was rebuilt.
An important part of the investment at Rönnskär was the construction of a new E-kaldo plant whose purpose was to improve the smelter plants position as world leading in recycling of electronic scrap. A side effect of the investment was an increased production of waste heat, something which prompted the construction of a new district heating facility.
Stig-Olov Lundström was the coordination manager for the new district heating facility. He says:
– The district heating facility utilizes the steam from the E-kaldo plant. It involves steam with 40 bar pressure which is distributed here in pipes with a diameter of 300 mm.

It is saturated steam with a temperature of 250°C which is then converted to 20 bar process steam and 3 bar process steam.
– We had discussed that we wanted a steam accumulator on the plant. And with this construction it became reality. Steam also charges the 230 m³ accumulator with a maximum pressure of 40 bar.

GreenExergy was hired to do the design.
– It was a complicated project under time constraints where the construction ran parallel with the erection of the E-kaldo plant. Our facility had to be ready to receive the steam from the E-kaldo plant when that was put into operation.

The district heating facility with its new steam accumulator works very well.
– We say that the steam accumulator is our best friend. If there is a power outage we are able to get going much quicker since we can increase the pressure in the system faster.
Since the plant consists of long highly pressurized pipes it is also required for inspection and it has been design reviewed by an accredited body. An unorthodox detail is that the steam relief valve has been placed on the roof, which leads to major piping but provides more space inside and increased safety and security in case of leakage.

– This is a complicated facility, top-of-the-line. We have dreamt of having a steam accumulator since 1985, and we are very happy that it is operational now. It entails big savings and because of decreased use of oil also contributed to a decreased environmental impact. Altogether a facility which works very well.

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