Cutting Fan Design Time and Developing New Product Lines

FLEBU has a 50% share of the world market for IG Fans which are an important component of Inert Gas Generator units installed on every oil tanker around the world. Their function is to insert Inert Gas and low oxygen content air into the tanks of the ship during unloading of the crude oil. Fans reliability is a primary concern as a malfunction can lead to catastrophic explosions. These types of blowers are therefore subject to very strict quality requirements where every unit is tested before delivery with a multitude of Class Tests, Capacity Tests and FATs.

Recent legislation changes impose a significant reduction in accepted maximum noise level on board of the ships, however noise insulation or acoustic enclosures are expensive solutions to the problem. “We want to attack the problem from the source” says Eriksson, “the idea is to reduce the noise generation of the fans by increasing efficiency and also changing their performance characteristics in order to closely match the best efficiency point to the actual duty point”. The ability of TURBOdesign1 to optimise the fan performance at a specific duty point is decisive. In the case of IG Fans this duty point is difficult to achieve being characterised by high pressure and very low flow for a fixed motor speed. “The solution obtained from TURBOdesign1 is completely new to us but optimizing the fan impeller design may reduce the noise generation by 5 to 6dB.”

Maritime

In the case of IG Blower, Eriksson says “The solution obtained from TURBOdesign1 was completely new to us but optimising the fan impeller design may reduce the noise generation by 5 to 6dB.”

Industry

In this case the key aim was to reduce the fans diameter while maintaining performance. Eriksson says “The fan impeller diameter was reduced considerably without compromising performances and, very important, efficiency.”

FLEBU delivers ID fans with power of up to 3 MW to all major manufacturers of Exhaust Gas Cleaning System (EGCS). ID Fans are used to extract the exhaust gases from the boiler in modern power plants. The present legislation regarding emission control from these plants has considerably increased the requirement on the EGCS of which the ID Fan is a part of. To stay competitive, FLEBU has constantly been looking for new solutions to reduce costs and improve performance.

“In this case, we used TURBOdesign1 to solve two challenges” says Eriksson. “First we want to reduce the size, these fans can be of up to 3.5 meters in diameter and manufactured in expensive materials, therefore even a small reduction in impeller size can lead to a large reduction in manufacturing costs. We also want to slightly increase the rotation speed in order to make it possible to implement the use of motors with a lower number of poles that in turn reduces the total cost of the motor significantly. The problem is quite complex, strength, resistance to fatigue, critical speed and natural frequencies are all conflicting parameters that had to be addressed. One unique strength of TURBOdesign1 is the ease by which you obtain a new optimized blade shape for each modification of the wheel design. This way we can experiment with different designs to solve strength and fatigue problems and still very quickly obtain the optimum blade shape. Once again, the capacity tests made on the first prototype were very convincing. The fan impeller diameter was reduced considerably without compromising performance and, very importantly, efficiency”.

“TURBOdesign1 has given new answers to really challenging problems” concludes Eriksson “it also raises new questions… Now we realise that it is only our own imagination that sets the limits to how we can develop optimum solutions for coming projects. With TURBOdesign1 we will raise the concept of ‘tailor-made’ fans to a new and much higher level.”