There's no better time to specify steam
March 1st 2007

In this article Gordon Bareham of Fulton Boiler Works (Great Britain) look at the use of steam for processing, and the savings that the new government backed ECA (Enhanced Capital Allowance) scheme can offer

As a safeguard against fuel price increases or even shortages, larger organisations are tending to move towards dual-fuel boilers and are combining this with newer technologies to help counter price rises using efficiencies. This has led to a growing interest in higher specification burners combined with already efficient steam boilers.

But before we examine steam in detail, let's start with a few basic points.

First, for most commercial and industrial applications requiring medium to high loads, it is usual to produce steam in direct fuelfired boilers, although electric boilers are available for smaller loads. Steam can also be produced in specialised boilers by indirect heating, using highpressure hot water or thermal fluid.

Next, let's compare centralised and point-of-use steam by looking at the relative benefits of two sites.

The first is using point-of-use steam to operate multiple processes using individual boilers to provide direct heat. As well as the individual boilers, this site will also require a fuel (oil or gas) distribution system to feed them, and a safe flue system for each boiler. The benefits of a point-of-use steam operation include shorter distribution pipe work and therefore fewer leaks; on-demand operation for cost savings; more flexible plant; and smaller plant room size.

The second site is using a centralised boiler with steam piped to the various locations that need it. Although this arrangement will need a much simpler fuel delivery system, it will require more pipe work to deliver the steam, and will therefore more susceptible to leaks. However, as steam is generated from water and simply condenses, it is inherently sterile and the leaks will not present a contamination risk to sensitive processes.

Special 'thermal storage' boilers are also available to meet the needs of certain types of process equipment that create transient peak demands. These boilers have a water content considerably greater than their standard counterparts, which enables a short-term supply of steam to be released should demand cause a significant drop in boiler pressure.

Pressure drops will cause the formation of 'flash' steam, as a proportion of the water spontaneously evaporates.

Direct steam injection is only appropriate to manufacturing processes where the inclusion of condensate from the steam is an acceptable ingredient in the finished product. This should not be a problem, even in the food processing industry, because, as previously mentioned, the condensate is sterile. However, it will be necessary to remove any debris such as scale and rust that might be liberated from the steam pipework. Culinary or other high grade filters are therefore needed, and it is good practice to use stainless steel pipework downstream of the filter.

Electricity, while inappropriate for largescale UK users due to its high energy cost, should not be dismissed by companies with smaller processes. As well as being much easier to operate, electric steam boilers usually benefit from low maintenance costs and are very clean, and can therefore be located within a production area.

With so many options available steam is still an effective and appropriate process heating medium for the 21st Century.

Having committed to a steam as an energy source, it is good business practice to consider its use for other applications.

Taking food processing as an example, it makes sense to use steam to wash down and/or clean-in-place (CIP) at the end of a process or the day's production.

Hot water for washing can also be costeffectively produced using a heat exchanger, eliminating the need for a separate hot water boiler and storage tank.

It is even worth considering steam for space heating in place of electric heaters, which are usually mounted at high level and can be difficult to maintain.

Finally, a steam boiler can provide costeffective humidification for buildings – especially office areas where the dry atmosphere created by air conditioning and modern ventilation systems often cause respiratory problems for some staff.

To further increase your return on investment and reduce overall running costs, optional ECA approved burners can be fitted to boilers such as Fulton's ninemodel RBC range of horizontal boilers, which are included on the Energy Technology List for the government backed ECA scheme. The Inland Revenue, DEFRA and Department of Environment are working with the Carbon Trust to operate the scheme, enabling businesses to claim 100% of their capital allowances in year one, for investments in qualifying energy saving technologies and products.

The ECA scheme allows businesses to write off the whole of the capital cost of their investment in these technologies against their taxable profits for the period in which the investment is made.

This provides a helpful cash flow boost and a shorter payback period. For new or replacement steam boiler installations, the scheme covers both capital plant and installation costs. Interest free 'Action Energy Loans' are also available to SMEs for boiler plant improvements and replacements if improved energy savings can be shown.

Based on 2004 figures for a steam plant in the North of England equipped with four boilers, the following estimates were calculated per boiler/burner: Typical additional cost per boiler with ECA approved Nu-way burner - £2,300 Estimated annual running-cost saving per ECA approved boiler (based on plant application and fuel used – gas and electricity) - £2,750 Payback period using ECA burner - less than one year With fuel costs now rising dramatically, these savings will increase and the payback period will reduce.

The more sophisticated the burner and control specification the shorter the payback period. In addition there are many other operational advantages in the ECA specification for boiler/burner equipment with modulating control and variable speed drive.

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