Grästorp, Sweden
The Challenge
The initial soot-blowing system, comprising of 9 valves on the 1st stroke (countercurrent), 5 on the 2nd stroke (wake), and 7 on the 3rd stroke (countercurrent), proved insufficient.
Despite the system, the boiler tubes were not kept clean, and mechanical cleaning was required multiple times per month. This led to increased maintenance, downtime, and reduced overall efficiency.
The Challenge
The initial soot-blowing system, comprising of 9 valves on the 1st stroke (countercurrent), 5 on the 2nd stroke (wake), and 7 on the 3rd stroke (countercurrent), proved insufficient.
Despite the system, the boiler tubes were not kept clean, and mechanical cleaning was required multiple times per month. This led to increased maintenance, downtime, and reduced overall efficiency.
The Solution
To improve boiler cleanliness and reduce manual intervention, it was decided to replace the soot-blowing system on the 1st stroke with an Aerovit ShockClean System.
Aerovit delivered new Aerovit ShockClean System mounted on a custom boiler door, optimized for reliable and continuous cleaning performance.
To improve boiler cleanliness and reduce manual intervention, it was decided to replace the soot-blowing system on the 1st stroke with an Aerovit ShockClean System.
Aerovit delivered new Aerovit ShockClean System mounted on a custom boiler door, optimized for reliable and continuous cleaning performance.
The Results
The retrofit showed immediate benefits:
• Mechanical cleaning on the 1st stroke dropped from several times per month to only twice a year.
• Tubes in the 1st stroke are now kept consistently clean.
• Tubes in the 2nd stroke are fairly clean.
• Tubes in the 3rd stroke still require further improvement.
A service inspection after 22 month confirmed that:
• The original soot-blowers on the 2nd and 3rd strokes (without cooling) showed significant dysfunction.
• All 12 valve diaphragms were damaged due to heat exposure and required replacement.
• Corrosion and soot buildup were evident, particularly in the shot tubes.
In contrast, Aerovit’s valves on the 1st stroke, even after 4 years in operation, were in excellent condition, with no need for replacement, demonstrating the effectiveness of the cooling-air design.
Overview
Grästorp Fjärnvärme AB is a district heating plant in Sweden, co-owned by Lantmännen Agroenergi AB and the municipality of Grästorp. The facility operates a 3.5 MW biomass boiler and is fueled by wood chips and Salix (willow). The plant originally relied on a traditional soot-blowing system installed at the top of the boiler, but struggled to maintain clean tube passes, leading to frequent manual cleaning and operational inefficiencies.
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