Steam gives Green’s Flour power

You might expect that doubling the output of a process would result in a near doubling of energy costs. Not so for leading food manufacturer, Green’s Flour. Since CFB Boilers replaced the company’s existing electric boiler with their high-efficiency 4VT steam boiler in February 2012, the flour miller is benefitting from an incredible 225% increase in process output – resulting in overhead savings of tens of thousands of pounds. Furthermore, the company is also on track to save an additional £21,000 every year on boiler running costs alone.

From its factory in Maldon, Essex, Green’s Flour manufactures and provides a wide range of speciality flours and flour-based products to independent bakeries, major food manufacturers and retail multiples. One of the major commercial by-products of Green’s Flours’ milling process is wheat feed, a highly digestible product which the company supplies to the animal feed industry.

As a raw product the wheat feed is loose and therefore difficult to store and transport. To improve distribution efficiency, Green’s Flour extrude the wheat feed into 10mm pellets, and it is during this process that steam is applied. Known as a ‘conditioner’, steam helps gluten in the wheat act as a binding agent – enabling the condensed, compact pellet form. The result is that one truck is able to transport 29 tonnes of pellets, as opposed to only 15 tonnes of raw wheat feed.

With storage and transport efficiency fully optimised, Green’s Flour recently turned their focus to the electric boiler used to provide steam in the extrusion process. “Energy efficiency and reduction of carbon emissions are key priorities for Green’s Flour,” explained Lawrence Potter, Operations Manager at Green’s Flour’s Maldon site. “As ops manager I’m always looking for ways to improve our manufacturing processes, and the electric boiler was a prime candidate as it was such a significant energy consumer,” he continued.

Green’s Flour’s 150kW electric boiler achieved an output of 1.2 tonnes of pellets an hour, and as a result had to be in operation 22 hours a day in order to maintain flow capacity. The running costs were high, so Lawrence contacted several boiler specialists to investigate energy-saving alternatives. It was CFB Boilers’ detailed solution that stood out, as Lawrence explained:

“CFB Boilers suggested that we switch from our electric boiler to their 4VT steam boiler and provided us with detailed analyses which compared our existing energy usage and running costs with their solution. They showed us that we could not only increase boiler capacity and speed up production time, but also save money on boiler running costs. It was a no brainer.”

CFB Boilers specified a 300kW 4VT steam boiler – which the company manufacturers at its Essex factory – for the project. As a gas-fired steam boiler, the 4VT has a distinct financial advantage over electric boilers – fuel cost. While rates vary, gas is approximately one third, or even one quarter, of the price of electric per kWh, meaning considerable savings can be achieved.

But the benefits of the 4VT boiler are not limited to the gas/electric comparison – the 4VT steam boiler is one of the most efficient vertical gas-fired steam boilers on the market in the UK. It is the only boiler in its class to offer four-pass technology (unlike the more common one, two and three pass designs from other brands), which means that combustion gases pass generated heat over water heating surfaces four times. This design maximises the opportunity for heat transfer, resulting in low exit flue temperatures and exceptional efficiency.

The four-pass construction also means that the boiler is able to reach full capacity very quickly – usually in just 15 minutes. This is a much faster time than many other vertical steam boilers, and significantly faster than most electric boilers.

Also contributing to high levels of efficiency is the 4VT’s steam chamber, which is approximately 30% larger than most other vertical boilers. This enables the boiler to respond quickly to any peaks and troughs in load demand, ensuring operational continuity, and avoiding unnecessary energy wastage. It also means that boiler priming – where water droplets are carried over with the steam – is virtually eliminated. The result is a much drier, higher quality steam, which significantly reduces system scaling, contamination and condensate losses, and increases the efficiency and longevity of the boiler plant.

Installation of the new steam boiler system began in late 2011. The first stage of the project was construction of the outside plant room, which Green’s Flour planned to complete in-house before CFB Boilers installed the steam boiler system. As a result, strong collaboration and communication between the two parties was essential, as Derek Parish, Managing Director at CFB Boilers, explained:

“Usually when a plant room is needed, our engineers will build it either on the client’s site or at our factory in Clacton. That way we can ensure that everything is done correctly, and that the installation will run smoothly. This project was different, with Green’s building the plant room themselves, but it was still absolutely vital that it was done properly. To achieve this we drew up the specifications for the plant room, including sizing and ventilation, and then gave advice whenever it was needed.”

Lawrence was impressed with CFB Boilers’ flexible approach: “The guys were really helpful, providing us with everything we needed for building the enclosure. And to their credit, the specs were spot on. It felt like a real team effort,” he said.

Upon completion and inspection of the plant room, CFB Boilers installed the 4VT steam boiler, ancillary equipment and pipework. The system was commissioned in March 2012 and since this time Green’s Flour has closely monitored its performance – with better than expected results, as Lawrence explained:

“CFB Boilers predicted that we would save £21,000 a year on boiler running costs with the new 4VT, and we’re right on track to achieve these savings, which is fantastic. But the impact that it’s had on production is astounding – the process is much, much smoother now that we have twice the steam power. And whereas we used to produce 1.2 tonnes of pellets an hour, we now produce 2.7 tonnes – production has more than doubled. This means that our process time has almost cut in half from 22 hours a day to just 13. We’re currently estimating exactly how much this is saving us, but it looks like it could be more than £70,000 a year. To say we’re delighted is an understatement.”

He continued: “CFB Boilers really delivered on this project. There were a couple of snagging issues after completion, but the team took care of them straight away, and have worked with us closely since to make sure we’re getting the most out of the boiler. For anyone still using electric boilers in their process, or even another gas-fired steam boiler, I’d highly recommend them to investigate whether they could improve on efficiency. It’s made a massive difference to our business.”

For more information on the 4VT boiler range, which spans thirteen models from 6HP to 130HP and can be natural gas, propane or oil fired, please contact CFB Boilers on 01255 224500 or visit the website www.steamboilers.co.uk.