"You'll never convince anyone that it's possible to filter coarse bulk with a cyclone that looks like that"
That’s how it sounded almost 20 years ago when the innovator Thore Fridhill introduced a completely new design on a cyclone to the coarse bulk industry. At that time, Pellvac Whirlwind was still in its infancy. But now it is 2021 – and Whirlwind has found a home among over ten thousand private households in Sweden. But how did this come to be?
What is the story behind Whirlwind? How did the Swedish industry in the late 90s reject this unique and non-conforming cyclone? That we will cover in this article.
Cyclone separation is nothing new. It has been common knowledge among engineers worldwide that cyclone offers the best degree of separation. But why is that? The particles are thrown into a contained tempest, thrusting towards the edges. When the particles have fallen, gravity takes over. The particles fall to the bottom while a tiny proportion, 1% or less, escapes through the eye of the cyclone
In a folder with notes that the innovator Thore Fridhill left behind, we could find what explains how the idea of a low-profile cyclone came to be. And a design that was considered controversial or next to impossible. But also a design that was considered controversial.
And it began in the early 90′ with a project that went by the name “The Spiral”. The purpose was to get Industries to stop using conveyor belts to transport raw materials.
The notes tell us how, in the aftermath of a project to get heavy metal industries to stop spilling raw materials, Thore stumbled into a problem. Clogged filters and low degree of separation in the cyclones. A more reliable filtration technique is needed. During his career, Thore had already designed large quantities of cyclone filters for industries worldwide. Many of these started with a cyclone top that continued down a funnel, where the air also passed textile filters.
It was not just a problem that many dust particles got stuck in these filters. The cyclone funnel was built on height and took up much space.
Is it possible to cut the funnel and only have the top of the cyclone? – is supposed to be a question asked to Thore.
He answered – Yes!
That would prove to be a presumptuous answer, which could end badly!
Thore was booked to demonstrate this at an exhibition in Hanover. The purpose was to show that a cyclone does not have to be shaped like a funnel. So Thore spent several evenings at the University Library of Lund to study everything related to cyclone technology. He also talked to other engineers and professors – and when he gathered all the valuable knowledge, he was convinced. It’s possible!
There was a shortage of time. Thore would demonstrate his prototype in Hanover in just a few days. So he started in his workshop outside Malmö, south of Sweden, constructing a straightforward cyclone top with a low height. The night before departure, he tested the new cyclone. He measured almost 90% separation! Regrettably, it was too late to cancel the exhibit.
He decided to take the bull head-on and think of a solution on the way down to Hanover. With a poor-performing cyclone top and books on physics, he drove at high speed to Hanover. Once there, he had one night in the hotel to devise a solution. He ploughed through the books again in search of what he had missed. He drew a strange figure in his notebook in the wee hours; -which would change everything.
He connected the cyclone. He started the vacuum cleaner – and measured 99% ash separation!
The day had come, and at the last minute, Thore had gotten hold of some glue and plywood. It is according to his notes here that the magic occurred. He had designed a vortex breaker.
Minutes before the doors opened and people streamed in, he could confirm that the glue was sufficient enough to hold the vortex breaker in place, under the top of the cyclone cap. He connected the cyclone. He started the vacuum cleaner – and measured 99% of ash separation.
So far, so good! He had proved it possible to get over 99% separation without filters, left the exhibition with the honour intact, and sensed how the industry would change forever.
Here one could imagine that the golden age would start. In a way, it did, but not in the way one might expect. The industries were challenging to convince. In the notes from Thore, there is something that can either be a quote from what someone told him or maybe the echoes of his thoughts. He was not known for having legible handwriting. But we suggest the following:
“You’ll never convince anyone that it’s possible to filter coarse bulk with a cyclone that looks like that”
This is a time when cyclones have always looked a certain way, and that has been enough. They were tall, cone-shaped and worked. Even if it meant regular filter changes, spilt raw materials, the strain on the environment, and perhaps even dangerous particles that leaked into the air as the workers breathed. This is what everyday life looked like in the 90s. Thore tried to convince the directors that his cyclone had better efficiency than the traditional one, but unfortunately, no one listened.
Here, history takes a turn, and we are approaching how it comes about that this cyclone, designed for heavy industry, came to be a hit among over 10,000 households instead.
In the late 1990s, the Swedish government voted for a new environmental policy. The purpose was, among other things, to get oil-heated houses to switch to environmentally friendly alternatives. This, in turn opened up a new market. The switch to wood pellet was the best solution for many with oil pans.
We are now in the early 2000s. Thore is constructing a vacuum system that shall transport the pellet from storage to the pellet stove. This is also where the cyclone returns to the story. Vacuuming pellets mean that sawdust and wood dust is released, and this will clog the central vacuum machine.
It turned out that the cyclone was the crucial detail required for the system to be functional. But, equally, there was another need among all the country’s new pellet users.
Yes, this cyclone became better known as an excellent ash vacuum extractor. Many wood pellet users out in the country tried to vacuum ash with filter-based vacuums. In forums like byggahus.se (Swedish forum), there are many threads where ash vacuum filter techniques are discussed and many nice DIY cyclones. We at Pellvac think that this is fantastic to see that Whirlwind regularly appears in these forum threads.
Yes, this cyclone became better known as an excellent ash vacuum extractor. Many wood pellet users out in the country tried to vacuum ash with filter-based vacuums.
In forums like byggahus.se (Swedish forum), there are many threads where ash vacuum filter techniques are discussed and many nice DIY cyclones. We at Pellvac think that this is fantastic to see that Whirlwind regularly appears in these forum threads.
Pellvac Whirlwind has not been marketed much over the years. Between 2010-2018, marketing efforts were less than zero. But through the phenomenon known as “Word of mouth”, sales through our retailers have steadily increased every year. In 2018, we rebuilt our website and started an online shop. With good search engine optimization (SEO), more people found Pellvac.
After following the number of Whirlwinds sold since the start, we can now state that in mid-September 2020, we passed over 10,000 Pellvac Whirlwind 20 litres sold.
And what’s more, the industry has softened in terms of our low-profile design and how well it works with various materials. That said, Whirlwind is not a cyclone technology that suits all industries – but it fits many. Without going into more detail, it is used today by smokehouses and concrete manufacturing. Pellvac Whirlwind may actually have occurred in making your morning coffee.
Thore, unfortunately, passed away in 2011. But he left behind a legacy that is preserved today by his sons. The eldest son has built heavy-duty vacuum machines together with his father since his teens and today runs the company from Strömsnäsbruk in Småland.
The youngest son flew to Vietnam in early 2020 and did not return home. Covid-19 closed the borders, and the youngest son, the author of this article, decided to ride out the storm in a foreign land. But we have understood after looking in the rearview mirror and going through Thore’s old notes that he was a visionary – and ahead of his time. We have learned that it merely took 10,000 satisfied household customers to get the industry to rethink.
In the same way, house owners were forced to abandon fossil fuels for domestic heating in the 1990s, the industry must now review how they affect the environment. For example, is it reasonable to waste 1-5% of raw material in production that may have been shipped across half the globe? Is it reasonable to drive x number of tonnes of spilt raw material and filter to the landfill annually?
2020 has been a very interesting year with many new developments in the industry. We hope to help more industries by implementing cyclone separation with Pellvac Whirlwind. Therefore, in 2021 we will pick out a prototype with cyclone separation on a dump container. We will return more about that later.
Whirlwind is also heading towards Europe. There are already several industrial companies in Switzerland that already use Pellvac, but many countries remain.
Since 2018, we also offer our products via our webshop, and more and more people choose to shop directly from us, who manufacture Whirlwind. We want to say thank you to you all! We are extremely grateful that you are involved and support us as a family business, but also save the Rainforest.
This is because we love bioenergy and want fossil fuels to be phased out. We want to reduce carbon dioxide emissions into the atmosphere. We want more countries to plant more trees. Carbon-neutral and carbon-negative solutions must be rewarded.
Therefore, we donate 5€ of each Pellvac product sold via the webshop to Save the Rainforest. On January 2, we paid €474 to preserve the Rainforest for future generations. Thanks again to everyone who contributed.
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