Hot on Energy Savings

There are many qualities that a bakery oven should offer: ease of installation and of use, reliability, adaptability and flexibility. In the context of sharp energy price rises, one issue is currently on everyone’s mind: energy consumption. Annie Launois asked oven manufacturers how they are addressing this problem.

Bakeries are currently operating in a difficult economic context. As Austrian firm König explained: “The increasing prices of raw materials make it very hard for companies to maintain low prices while offering the high quality that clients demand”.
Raw materials are not the only things that are getting more expensive. In the context of high energy costs and environmental concerns, food processors are increasingly looking to reduce their energy consumption in order to maximise the ‘price/performance ratio’ and maintain their profit margins.

As a result, when buying or renewing equipment, bakers are looking for ovens that are energy efficient and more ecological.
A large variety of baking systems is available on the market: directly fired ovens, indirectly fired convection ovens, hybrid ovens, thermal oil systems and stone band ovens.
In terms of energy consumption, indirect-fired ovens are usually considered to be less efficient than direct fired ovens as they tend to lose energy during heat transfer. However, equipment manufacturers have been working on ways to
solve this problem.

RIGHT CHOICE

Usually, the choice of ovens depends on the products manufactured. There are also geographic variations.
Turkington USA produce direct gas fired ovens. William Terry of Turkington told European Baker: “I believe that most of the ovens sold in the European market are indirect fired ovens”.
Turkington has completed installations in Spain (La-Familia) and Germany (Wendelin), both with US style products.
“With energy costs continuing to increase, our customers are turning to us to provide that ability to track and control these costs”, he said.
Britain’s Spooner Industries Ltd has expertise in air flow and forced air convection. Steve Newell of Spooner confirmed that “the hot topics in the oven sector include energy usage, plant flexibility and training”.
Newell explained: “The Spooner oven design is based on forced air convection, which is inherently one of the most energy-efficient oven technologies. In terms of customer requests, this has translated into a general move towards higher technologies and from traditionally indirect fired systems to direct fired forced convection.”
Spooner has incorporated a variety of technical solutions to reduce energy consumption including thicker insulation of the oven units, inverter driven fans, and enhanced controls to enable turn-down to low fire when there is a break in production.
Newell added, “We also use heat recovery systems to further enhance the energy efficiency of our equipment and reduce the energy cost per product”.

COST CUTTING

König ovens are indirect-fired convection ovens, available with a gas or oil burner and as electric ovens. Engineer Helfried Enzi of König told European Baker, “Energy savings have become a major topic in the oven sector in recent years”.
According to the firm, its rack oven, the Roto Passat, offers low heating costs thanks to the large surface area of the heat exchanger.
The air which flows back out of the baking chamber is heated by the flue gases from the burner chamber and flows back into the baking chamber. The air-circulation fan transports the hot air to the baking chamber and returns the air from the baking chamber to the heater. The company has also put the emphasis on insulation and has fitted the oven door with double glazing.
To achieve further energy savings, Konig is planning to increase the overall thermal efficiency
of the heat exchanger used in its ovens.
“The objective is to gain maximum utilisation of the primary energy input in the oven in order to minimise energy costs,” said Enzi.
The company is also planning to provide its customers with optional packages for heat recovery, which can lower the costs of general heating and warm water supply.

SAVINGS PLAN

Denmark’s DFE Meincke, a global manufacturer of processing plants for the baking and confectionery industry, also takes energy savings seriously.
“There’s no doubt that the hottest topic at the moment is waste reduction; waste with regards to raw materials and especially energy. This is, of course, a result of the recent price increases in
both areas,” Kenneth Petersson, research and development engineer, DFE Meincke, commented.
According to Petersson, “To reduce energy consumption, you need to increase the overall efficiency of the baking system. Too often, heat is wasted through the system instead of going into the product.”
In the baking process, it is a matter of achieving an even heat distribution across the band together with the correct temperature and moisture profile.
DFE Meincke supplies all three major heat transfer systems: convection (Turbu Three indirect convection oven), direct heat (Direct Three DFG oven) and radiation (Radiant Three cyclothermic oven).
Its latest oven, the Turbu Three Green oven, is a convection tunnel oven, with indirect heating by means of oil, electricity or gas, which was launched at Interpack in April. In its marketing brochure, DFE Meincke claims that its third-generation Turbu oven has been “especially designed to minimise energy consumption”.
“First, we have looked at the entire inner structure of our ovens to determine which areas cause unnecessary heat bridges and which areas need extra insulation,” Petersson said.

PHOTOGRAPHY TOOL

A very effective tool for this process is thermographic photography which clearly shows how the heat is distributed through different materials.
Marlene B. Pedersen, sales and marketing consultant, DFE Meincke, continued, “Second, we have improved the design of our cleaning hatches to give a tighter seal around the oven chamber and to eliminate any heat bridges in this area
as well.”
The company has also updated and reintroduced the previous concept of using covers for the return band. The covers help to preserve the heat from the return band, therefore reducing the total energy consumption in the oven.
DFE Meincke also outlined that its heat recovery unit is designed to take the hot exhaust air from the burners (in the case of an indirectly heated convection oven) and the humid air from the oven chamber and use them to heat up the fresh air intake. In this way, the system makes use of all the energy available, lowering the overall consumption.

HOLISTIC CONCEPTS

German firm Miwe has also noticed that food processors are increasingly paying attention to energy consumption.
The company said that it now receives numerous enquiries concerning energy savings from bakeries in the whole of Europe, especially in countries with comparably high energy prices such as eastern Europe.
Miwe believes that there is a huge market for “holistic and long-term alternative energy concepts to optimise heat recovery solutions”. However, Charlotte Steinheuer of Miwe said that new energy saving concepts are often “not fully thought-through, leaving the baker with limited savings”.
In this respect, it is important to work closely with the bakery to design the best solution as the customer has an enormous influence on energy consumption by way of maintenance, measured steam input, and full loading of the units.
Miwe claims that, with the replacement of older ovens by new units, it is possible to achieve energy savings of up to 20-30 per cent.

According to the firm, these measures can help to reduce energy consumption:
• Down-function to provide automated shut-down of
• store baking ovens for periods of non-use.
• Half-load button – gradient baking.
• Various ovens are prepared for energy management systems.
• Sealing through air-control during steam input.
• Hearth door insulation, heat protection glass.
• Choice of high-quality insulating materials, such as mineral fibre with a strength up to 300mm.
• Partially (rack and ideal) very low flue gas loss of about 10 per cent.

STEAM-PROOF DOORS

The company has just introduced ‘MIWE eco: Nova’, its new heat recovery concept. Miwe claims that through the separate handling of steam and flue gas, not only the efficiency, but also the longevity of the system can be increased. “Our customers can view and supervise the recovered energy directly on the MIWE TC control system, making the amortisation period especially transparent.”
For speciality bread company Honeytop, the baking process plays a key role.
Honeytop’s founder, William Eid said, “It is difficult to attribute success to just one factor. However, we pride ourselves on the quality and authenticity of our products, and our ovens certainly play a key role here”.
Honeytop has designed and built soft-fired, tandoori-style clay ovens that allow it to produce authentic naan breads.
Eid told European Baker, “We opted for an in-house design because there were no ovens available that could replicate a traditional ‘Tandoor’ in the way it bakes naan bread. The bake profile required to produce truly authentic naans is quite unique in the way the oven imparts heat to the dough.”
Honeytop’s ovens are clay lined, fired by soft flames. TheY explain that this, paradoxically, results in a very intense heat being imparted onto the dough, allowing for a quick bake and hence soft, moist breads with some crisping on the base.
Honeytop tracks its energy use very closely and it is in the process of installing several energy saving measures in its bakery.
These include mechanisms to reduce gas usage whenever there are gaps on the line, and heat exchangers on oven chimneys.
“We constantly strive to improve production efficiencies in order to make the best use of the gas that we burn,” Eid added.
As Steinheuer of Miwe concluded, “The excitement and curiosity concerning further developments in the field of energy savings is increasing”.
At the same time, bakers will expect the quality of the baked goods to be preserved as their customers expect premium quality from them.
Only when these conditions are met will they be willing to pay an adequate price for their products.