Plant & Works Engineering
A new approach?
Published:  22 February, 2019

PWE spoke to Fulton’s Carl Knight about the company’s new VSRT.

Fulton’s Carl Knight says the claims made by vertical steam boiler manufacturers are easy to get excited about, especially at a time when stringent industry and environmental standards – such as the MCPD and London’s Air Quality Strategy – are making the headlines. Indeed, Knight told PWE that it has its own claims to make about its own VSRT, which he says is the most “radical change to vertical steam boiler design” since 1949.

He explains that Fulton’s new VSRT is “a ground-up, clean-slate design approach that combines new people with new skills, has brought a new approach to the design and optimisation of heat transfer solutions.” But let’s look at the company’s new VSRT in more detail.

Energy efficiency

With full operating performance curves available throughout the full range of output – and at various operating pressures – Fulton claims its VSRT provides very high operating efficiencies (84% gross thermal efficiency compared to approximately 80% from equivalent models), which result in lower operating costs.

These operating efficiencies are achieved, according to the company, thanks to the VSRT’s long heat transfer path and double-wall annular spiral rib heat exchanger that are fully-water-backed. This means that heat is transferred in two directions to double the heat transfer area in a fixed volume. The fully-water-backed design of the VSRT also allows low jacket loses which, combined with low flue gas temperatures, provides the highest thermal efficiencies.

Its combustion technology – featuring a Fulton-designed modulating burner and furnace that have been designed as a single component and fully-matched with the VSRT in mind – has also helped, according to Fulton, to achieve ultra-low NOx emissions of less than 20ppm and up to 10:1 turndown capability. Additionally the company claims, when correctly sized for applications, the high turndown of the VSRT will result in savings above and beyond those gained from the stated efficiencies.

Steam output & quality

Knight also claims that at 1306 litres, the water volume of the VSRT-60 is almost 120% greater than equivalent 60HP vertical tubeless steam boilers yet, despite the increased volume, the VSRT, according to Fulton, still boasts a start-up time of 10-15 minutes and its installed footprint is up to 25% smaller. At 8 bar, Knight says the VSRT also achieves a 99.75% steam quality.

Durability & warranty

Knight believes that thanks to its down-firing burner alignment – that eliminates flame impingement on the pressure vessel – and the VSRT’s patented spiral-rib heat exchanger design that virtually eliminates thermal stress, Fulton has created a longer-lasting boiler. He adds, this is why all its VSRT models come with a 10-year warranty on the pressure vessel.


With features including a tubeless design, no internal refractory and air filtration system as standard, Knight also says the VSRT is extremely easy to maintain: “For applications where contaminated air can reduce boiler uptime, the VSRT’s standard-fit cyclonic air filter effectively separates debris and damaging particles from the combustion air and, because it won’t clog over time, eliminates the need for replacement filters. Maintenance is further improved thanks to the VSRT’s industrial control platform and easy access to the pressure vessel.”

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