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Steaming ahead with cost savings

15 October 2017

Derek Parish comments on the growing popularity of steam boilers in the food production sector. 

Boilers are at the heart of many food plant operations, principally because heat is required at almost every step of production – from cooking to cleaning. A notable trend is the increasing popularity of steam boilers, largely as a result of their ability to improve both a company’s bottom line and its environmental footprint. 

Steam is required in just about every industrial food process at one or more stages of production, primarily as a source to heat food and for decontamination. The benefits of steam are many. First and foremost, the hygienic quality of steam makes it safe for direct contact with food products, while also virtually eliminating microbiological risk in food. The hygienic nature of steam also allows it to be utilised for packaging sanitisation prior to filling, as well as pasteurisation or sterilisation of packaged food, while a further use is equipment and plant cleaning/sanitisation. 

Gas steam boilers offer numerous advantages over their electric counterparts. Most importantly, they are cheaper to run than electric boilers, with electricity being up to four times more expensive than natural gas. Steam also offers far better temperature control, which helps to prevent scorching of food ingredients, equipment and plant operatives. The ability of steam to provide uniform heating, rapid heat transfer and easy control of the heating rate also makes steam boilers suitable for meeting the precise heat requirements of a range of food processing applications, including jacketed kettles, ovens, fryers, and belt grills.

Getting the desired results
However, to achieve the desired results – whether boiling of wort in breweries or crusting bread rolls in bakeries – steam must delivered at the right time, at the right temperature and at the right quality. (for example it must be dry, not wet). In this regard, the functionality and capability of the selected steam boiler is paramount.

Consider the number of times that combustion gasses within the boiler transport generated heat over the water heating surface, for example. Most conventional steam boilers use two- or three-pass designs, but to maximise the opportunity for heat transfer it is worth seeking out solutions that surpass this benchmark. The knock-on benefit of a steam boiler capable of, say, four-pass functionality is very high efficiency and low exit flue temperatures. Four-pass construction also means that the boiler can reach full capacity more quickly – typically in just 15 minutes; far quicker than many vertical steam boilers, and significantly faster than most electric boilers. 

Maldon-based Carr’s Flour Mills (previously Green’s Flour) offers a good example of the benefits of steam boilers. Since the company’s original electric boiler was replaced with a four-pass 4VT steam boiler from CFB Boilers, the plant has benefitted from a 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.

A commercial by-product of the company’s milling process is wheat feed, a highly digestible product supplied to the animal feed industry. The feed is produced in pellet form by extrusion. However, the electric boiler serving this process was a major user of energy, and the company opted to replace it with a 300kW 4VT.

In addition to savings in boiler running costs, the use of steam power has had a significant impact on production. For example, with the electric boiler the mill produced 1.2 tonnes of pellets an hour; with the steam boiler, the mill is able to produce 2.7 tonnes. So, steam has more than doubled the production rate of pellets. This has cut the mill’s process time by almost half – from 22 hours a day to just 13 – saving the company an estimated £70,000 a year.

It is worth paying close attention to the size of the boiler’s steam chamber. A large chamber will enable the boiler to respond more 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 drier, higher quality steam, which reduces system scaling, contamination and condensate losses, and increases the efficiency and longevity of the boiler plant.

Derek Parish is managing director at CFB Boilers.

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