Boilers – the energy source

Attaining higher levels of efficiency

1 August 2008



With laundries under pressure to reduce their environmental impact and energy consumption, boiler systems must operate at peak efficiency if they are to succeed, says Tony Vince


The rising cost of energy and the increasing pressure to become “greener” is forcing laundry operators to make economies wherever possible.

While the cost of fuel is of concern to businesses of all sizes, it is the large industrial laundries that have most to lose through inefficient steam generation.

The boiler house is a large user of energy and every effort should be made to maintain boiler systems at peak efficiency to reduce operating costs and environmental impacts. The benefits of doing so include a reduction in the company’s fuel bill.

In most laundries, energy is used in the form of

steam in two ways:

• to heat water from cold to process temperature (in some cases as high as 85C). This water is eventually dumped into the sewer untreated;

• to dry the garments. The steam is then returned to the boiler and the excess is flashed off via a chimney into the atmosphere.

There are several options open to a business faced with rising costs in energy, effluent and fuel – to ensure its existing boiler system is operating at peak efficiency or to consider alternatives.

There has been great interest in the concept of the “steamless” laundry, and the development of low temperature washing systems, that reduce energy consumption and lessen the impact on the environment.

According to Jensen Group’s Jap Hobbel, its steamless (direct-fired) laundry concept for industrial laundries can dramatically reduce electrical consumption. Hobbel says the Jensen Group is focused on developing machines that operate by direct gas heating. This provides higher productivity and minimises energy and water consumption.

In certain markets, there is greater interest in thermal oil systems used to heat flatwork ironers, which are said to offer greater productivity per unit floor space.

Thermal oil systems can generally operate at higher temperatures than steam systems, with the pump discharge providing only enough pressure to overcome pipe friction. André Güdel of Regiomat in Switzerland says there are several drawbacks to the use of steam in a modern laundry. “By contrast, he says an oil system provides efficient heating of dryers and ironers with operating temperatures between 180 – 220C with an injection regulation.

Options for traditional boilers

So where does this leave the traditional boiler? One option is for a water recycling system that effectively reduces live steam demand from the washer-extractors, which has the effect of increasing boiler efficiency.

The Petersfield and Reliance laundry in Hampshire invested in a Kemco System supplied by Dunlop Design Engineering in Ulster. The system has allowed the laundry to successfully make the transition from what could be described as a “traditional” steam laundry set-up to becoming a leader in energy, water and effluent saving. According to Dunlop, the benefits for the operator are stable costs, and 20% increased turnover – from £1.5m to £1.8m after the system was commissioned.

As water is recycled back for reuse at 50C this reduces live steam demand from the washer-extractors which has the effect of increasing boiler efficiency as well as improving steam pressure across the laundry.

Hugh Jones, carbon management account manager at the UK’s Carbon Trust, says the laundry industry is becoming increasingly energy and resource conscious and this will develop. Jones estimates the industry spends £300million

a year on energy, but adds that savings of up to 20% could be achieved in laundries where basic efficiency measures have yet to be undertaken. The Carbon Trust is committed to helping businesses reduce energy use.

Free energy audit

Laundry businesses that have an annual energy bill

of more than £50,000 per site can qualify for a free energy audit which identifies wastage hot spots while smaller businesses can apply for an interest-free loan for the purchase of energy-saving equipment.

According to Helen Shepherd, the marketing and finance director at Byworth Boilers, cash flow has always seemed to be a major challenge in the laundry industry and this has forced capital investment decisions to be based on purchase price.

On the whole, cheaper boilers tend to have a much shorter lifespan, and consume more fuel to produce the same output. If the laundry’s business plan is only projected for a couple of years, the fact that a slightly more expensive boiler would last for 25 years and cost much less in fuel seems irrelevant. “However the phenomenal rise in gas, oil and electricity prices has

led to more forward thinking decisions on capital investment,” she says. “Leasing and HP help to spread the cashflow hit, and now the Carbon Trust’s interest-free loans are enabling many more businesses to invest in energy saving equipment of all types.

“I think fuel bills are a more urgent point on any business agenda as they hit the bottom line directly.” She adds: “Any steps we can all make to saving fuel,

be it gas, oil or electricity will in turn reduce carbon emissions.

She explains that this applies especially to boilers as they are heavy fuel consumers. Taking simple steps to minimise leaks, keeping the boiler in tip-top condition and running the most efficient boiler you

can afford will reduce a laundry’s emissions.

Shepherd says laundry operators should undertake

a thorough boiler house survey, eradicating leaks of steam or water, ensuring insulation is complete and effective, and properly treating the feed water.

Horizontal boilers are the choice for industrial laundries, certainly from 1,000kg/h of steam demand upwards, because of their efficiency and reliability. Laundry equipment is taxing on a boiler because demand rises from 0 to 100% almost immediately. The larger water surface area of a horizontal boiler can cope with this more easily than a vertical design.

The horizontal boiler traditionally comes in two types, the reverse flame and the three-pass wetback. The reverse flame boiler is the most common choice for industrial laundries and is so called because the flame reaches the end of the furnace then returns on itself. The hot gases then pass through boiler tubes through the water space before waste gases leave through the flue. Heat transfer from the hot gases in the furnace and tubes to the water to raise steam is therefore critical. The less heat that is left to go up the chimney, the better.

Researching efficient design

Byworth embarked on a joint R&D project with Leeds University three years ago to design the most fuel efficient steam boiler available in the UK. “We predicted the effect that fuel prices would have on industry, and that all equipment would eventually be judged on its running costs as much as on the purchase price,” says Shepherd.

As a result Byworth launched the Yorkshireman2 steam boiler. Based on the original design, the Yorkshireman2 incorporates the X-ID boiler fire tube. The boiler was rigorously tested by Leeds University and Byworth Boilers.

The Yorkshireman2 is said to deliver an efficiency improvement of up to 3% over other new boilers, and perhaps up to 20% over an old inefficient boiler. This could lead to 20% reduction in fuel bills for the next 20 to 30 years, says Shepherd.

Another manufacturer that is putting resource saving technology into practice is Trevil. “Saving energy is definitely a priority – because we are all becoming more and more environmentally conscious, and because saving energy and water means saving money,” according to Trevil’s business development director Corinna Mapelli.

The Italian-based producer of finishing equipment for the laundry and drycleaning industry also sells electric steam generators of up to 24kW, or 58kW in rare cases, to the garment care market and particularly the drycleaning industry. “ Beyond this size, the choice usually goes to fired boilers.

Trevil focused its developments on solutions that save water and electricity. These include re-using as much as possible of the condensate’s residual heat; reducing heat loss by using good insulation around the pressure vessel and condensate recovery tank; and improving the thermal efficiency of the heat exchanger inside the boiler to provide maximum steam production per kilowatt.

Boiler users are having to comply with new regulations. Several EU countries, including the UK, forbid discharging hot water into the drainage system. Operators must recover the condensate and install “cooling-down” tanks for hot water (coming from the overflow of condensate tank or from daily blowdown of the boiler). All the connections between the boiler and these tanks must be secure, thermally insulated and periodically inspected.

Trevil boilers comply with European directives on safety of pressure equipment and electric appliances, says Mapelli.

The range goes from 7.5kW to 120kW. All generators include pump and electronic level control for automatic refill, stainless heating elements and fireproof insulation. All generators have modular heating elements, which supply power when required in convenient 6kW or 7.5kW steps.

Each generator in the range has an optional stainless-steel recovery tank, an economiser (a device that uses the residual heat of condensate to pre-heat fresh water) and other tanks for cool-down.

Fulton Boiler Works developed its RBC horizontal wet back fire tube boiler in response to demand for higher capacities than the practical maximum of 960kg/h

for its vertical range. With capacities from 957 to 4,787kg/h, the RBC is ideal for larger laundry installations and can be specified with gas, oil, dual fuel or higher specification, ECA-approved burners.

Fulton’s popular Series J vertical steam boilers are suitable for medium-sized laundries. Of tubeless design, they are capable of covering outputs from 96 – 960kg/h and operating pressures up to 10.34 bar, and can raise full steam output in just 20 minutes.

Bespoke version

Dublin-based Concord Boiler Engineering recently installed and commissioned a Fulton gas-fired steam boiler for the laundry at Peamount Hospital near Dublin, replacing an ageing boiler that had been decommissioned. Due to the boiler room’s location, small size and poor access, a bespoke version of Fulton’s gas-fired 40E steam boiler was specified for the project by the hospital consultants J V Tierney & Company in association with Concord Boiler Engineering.

Concord project engineer Jim Byrne said: “We realised that Fulton’s standard Series J boiler was not only too big to go through the doors, but would also not fit next to the existing backup boiler. Thankfully Fulton agreed to build a bespoke version, which is shorter and fits perfectly.”

For smaller laundries and drycleaning applications, Fulton produces a range of compact electric steam boilers. The eight-model Electropack range is designed for steam loads up to 160kg/h. The boiler can be sited conveniently to provide “point of use” steam, even in retail outlets.

The heating elements are individually switched to allow the boiler to respond quickly and efficiently to variable steam demands.

For steam loads up to 104kg/h the compact eight-model Dragon range is fitted with low watt density “Incoloy” elements that can be operated independently to allow boiler output to match steam demand. The smallest boiler, which is designed for positioning under normal-height working surfaces, is the Mini Compack with four sizes delivering between 14 and 27kg/h.

Controlled Flame Boilers produces the 4VT vertical range, which can provide outputs of up to 2,000kg/h, using 30% less fuel and considerably less time to reach full pressure. The steam chamber of the 4VT boilers is designed to be approximately 30% larger than most other vertical boilers, therefore enabling it to respond more effectively to peaks and troughs in demand, says CFB.

Two common problems encountered in the laundry sector are wet steam, which contains water droplets and effectively insulates the heat transfer surfaces, and priming, when a sudden surge in demand causes an abrupt drop in boiler pressure and the entire contents of the boiler turn to a foam. This can flow into the steam main and so bring the entire plant to a halt.

CFB says the increased capacity of the 4VT boiler virtually eliminates the possibility of priming and avoids excessive amounts of moisture being carried over in the steam-creating dryer stream.

Dry steam also avoids the deterioration of both the plant’s pipe work and the steam batteries that convert the steam to heat. As the generated heat is passed over the water-heating surfaces four times, by means of four specially engineered ports and fins, the 4VT is able to make best use of combustion gases.

Drycleaners with limited shop space can opt for the Slim Jim. Part of the 4VT series, the Slim Jim vertical boiler is designed to produce up to 159kg of steam per hour and can fit through standard doorways and fit into corners, so making it much easier to install.




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