HRS System Helps Muntons Turn Waste Malt into an Asset

Based in Stowmarket, Suffolk, Muntons is a malted ingredients company with sustainability at its heart. Using 250,000 tonnes of barley to manufacture 180,000 tonnes of malt pa, the firm not only sells its malt to the brewing and distilling industry but also make a range of malted ingredients used extensively in diverse applications such as food, confectionery and baking. Established in 1921, Muntons supplies over 60 countries worldwide including leading brands Heineken beer, Weetabix, Maltesers and Ovaltine.

_HRS Muntons Digestate Pasteurisation System (DPS)

The company is currently putting the finishing touches to its £5.4m on-site anaerobic digestion (AD) plant. Integral to the success of the 499 kW facility is a 3 Tank Batch Sludge Pasteuriser System with Energy Recovery from HRS Heat Exchangers, which will help turn 80,000 tonnes of Muntons’ liquid malt waste into valuable biogas and a high quality organic fertiliser. This biofertiliser will be then be applied to local farmland, helping the company’s network of growers to produce the barley needed to make Muntons’ malt – a perfect closed loop solution.

Anaerobic digestion is the natural breakdown of organic products, including food and drink waste, energy crops, farm waste and sewage. The AD process releases a methane-rich gas, known as biogas, and generates a biofertiliser, known as digestate, which is rich in phosphorous, essential for the growth of all living things. AD is a fast-growing industry in the UK and has seen a steep rise in operational plants: from 192 in 2009 to 335 in January 2015. AD could deliver 10% of Britain’s domestic gas demands and reduce UK greenhouse gas emissions by 2%+ if industry reaches its potential: 40TWh of energy. There are many AD facilities treating municipal food waste, farm waste and sewage waste, but there is also a growing trend for on-site AD plants at food and drink manufacturing facilities. Companies such as Nestlé, Diageo, Barfoots, QV Foods and Wyke Farms have all developed on-site AD plants with wide-reaching benefits: energy and heat generation; better waste management; production of a quality biofertiliser; and, not least, revenue from the sale of energy to the national grid, and from government incentives such as the Feed-in Tariff and Renewable Heat Incentive.

Muntons first became interested in AD after analysis showed that 60% of the carbon footprint of its supply chain came from the artificial fertiliser used by its barley growers. The firm realised that processing its liquid malt waste through an on-site AD plant would not only produce a high-quality digestate for its farmers to use instead of artificial fertiliser, it would also cut 3,000 tanker movements per year as there would be no need to transport its liquid waste off-site. And, thanks to the production of biogas, it could also generate 25% of the site’s electricity demand.

Matt Hale, International Sales Manager at HRS:

“For Muntons, this whole project has been about maximising efficiency. Although they have an abundance of heat, they still wanted to recapture what they could and our heat exchangers will provide at least 40% heat regeneration.”
The HRS system works on a three tank principle; while one tank is being filled, the second tank holds the digestate sludge at 70°C (the optimum temperature for pasteurisation), at the same time as the third tank is being emptied – each process lasts one hour. Waste cooling water from the CHP engine (which converts the biogas into heat and power) is used to heat the sludge in corrugated tube-in-tube heat exchangers; this is more efficient than heating an entire tank of digestate. HRS has also incorporated an energy recovery section into the process to make it even more efficient: energy is transferred from the hotter (pasteurised) sludge to the colder (unpasteurised) sludge, reducing energy consumption by up to 70% compared to normal systems.

The HRS system works on a three tank principle; while one tank is being filled, the second tank holds the digestate sludge at 70°C (the optimum temperature for pasteurisation), at the same time as the third tank is being emptied – each process lasts one hour. Waste cooling water from the CHP engine (which converts the biogas into heat and power) is used to heat the sludge in corrugated tube-in-tube heat exchangers; this is more efficient than heating an entire tank of digestate. HRS has also incorporated an energy recovery section into the process to make it even more efficient: energy is transferred from the hotter (pasteurised) sludge to the colder (unpasteurised) sludge, reducing energy consumption by up to 70% compared to normal systems.

“The fact that the HRS system offers batch reporting was also a big draw; traceability is very important to us,” remarks Lawrence Howes, Project Engineer at Muntons.

For a food production company used to operating under strict hygiene and quality standards, this level of traceability was a key factor in its selection process.The HRS heat exchanger technology provides batch reporting for full traceability To satisfy growers’ need for a high-quality fertiliser, the digestate will be pasteurised to meet stringent PAS 110 standards using the HRS Heat Exchangers 3 Tank Batch system. As well as a comprehensive proposal, the Muntons’ team was impressed by the HRS system, which can save up to 70% of heat required, as well as its ability to run at a half flow rate, should the volume of digestate stock reduce. Additionally, the equipment’s monitoring feature enables Muntons to track every batch of digestate back to the feedstock from which it was produced.

The HRS system works on a three tank principle; while one tank is being filled, the second tank holds the digestate sludge at 70°C (the optimum temperature for pasteurisation), at the same time as the third tank is being emptied – each process lasts one hour. Waste cooling water from the CHP engine (which converts the biogas into heat and power) is used to heat the sludge in corrugated tube-in-tube heat exchangers; this is more efficient than heating an entire tank of digestate. HRS has also incorporated an energy recovery section into the process to make it even more efficient: energy is transferred from the hotter (pasteurised) sludge to the colder (unpasteurised) sludge, reducing energy consumption by up to 70% compared to normal systems.

Lawrence comments on his equipment decision making process:

We were already aware of the quality and reputation of HRS Heat Exchangers in the food production industry – using their solution enables us to make use of an abundance of waste hot water. Not only does the corrugated tube-in-tube technique deliver improved performance, they’re also more resistant to fouling, which means less downtime and maintenance. In addition, we had a short deadline – just 16 weeks – which HRS was able to meet easily.”

The team at Muntons credits the AD plant with reducing risk to its business. “We generate a significant amount of liquid waste and if we were unable to get that off site – for example, if there were adverse weather conditions or problems with the tankers – then production would have to stop,” explains Mick Cochrane, Environment Manager. “Now that all our waste is being fed into the AD plant, we don’t have that worry. We’re also protecting ourselves against future increases in our utility bills by generating our own energy. And, by supplying our growers with digestate derived from the barley used to make our malt, we’ve reduced our CO2 emissions by 1159 tonnes pa (from 27,264 to 26,605) – the equivalent of
running 300 average family cars per year (approx).”

The AD plant is currently undergoing commissioning and will become fully operational in late spring, with payback expected within four years.

 

 

 

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