Several years ago Air Management Technologies was approached to develop a way to eliminate the use of boilers in bakeries, as well as reduce energy cost. It may have seemed a little far fetched at the time but it is now a reality in a state of the art bakery facility located in Elkhart, IN.  Today if you were to visit this plant you would find no boiler room, but you would find an innovative heat recovery system supplying proofers and fermentation rooms with over 500,000 BTUH worth of energy and the future potential to deliver over twice this amount.

OLD SCHOOL

Steam boilers have been the traditional way of providing process heating in bakeries for many years and given their ability to directly satisfy the humidification “wet-heat” requirements while providing a reliable heat source was a good fit. Times have changed with energy costs more than doubling over the past few years and with volatility still a major concern efforts must be taken to remain competitive. Oven/Oxidizer heat recovery is a step in the right direction as it eliminates the need for a traditional boiler room and the building cost associated. Combine this with lower installation costs versus steam, as well as decreased maintenance and energy costs, while being environmentally friendly and you have a Win-Win project.

ENGINEERING & DESIGN

Engineering and installation of the heat recovery system was accomplished by combining our expertise in managing the distribution and control of the energy source with the oxidizer manufacturer which provided a heat recovery coil to generate the desired heating output as a integral part of their equipment. The results were a complete system that delivered on all promises.

GUARANTEED ENERGY SAVINGS

The system is monitored 24/7 by a web-based controller that allows a window into the system and logging of performance to verify savings with current estimates in excess of $40,000 per year and future increases that could more than double this amount. This system also provides a degree of protection against natural gas price volatility as savings will increase proportionally with natural gas prices. Heat recovery is also very efficient in delivery of the energy source greater than 98% when compared to traditional boilers at 70%.

Whenever implementing a project like this return on investment is a primary concern and this case was no exception, as the cost was entirely defrayed by eliminating the conventional steam boilers so savings began immediately providing a positive cash flow.

The system serves various points of usage including several proofers and fermentation rooms with future provisions for an additional line and plant water heating requirements. System operation is accomplished by utilizing heat from the oven exhaust stream that passes thru the plants catalytic oxidizer which is equipped with a recovery coil and control elements to regulate the heating output. Two outdoor gas-fired copper-tube water heaters are located beside the buildings glycol refrigeration system with a footprint about double the size of a residential air conditioner. The water heaters serve several purposes including backup in the event of primary system failure, operate during cold starts and as a peaking device to maximize recovered energy usage.

Central hot water distribution loop provides heating from the recovery system to proofers and fermentation rooms heating coils at a temperature between 200º-210ºF, and by incorporating a combination of compressed air atomization and high-pressure humidification systems both dry and wet heat loads are satisfied at a fraction of the cost. Control of the processes is maintained by a combination of direct digital controls and interfaces with vendor equipment as required.

ENVIRONMENTAL BENEFITS

Environmental impacts now and in the future are a major consideration as we see an increased commitment to managing air and water quality to improve the environment. This was also a major driving force behind this initiative and this project alone will eliminate several hundred tons of Greenhouse Gas emissions per year.

CONCLUSION

Considering all the benefits of heat recovery it is hard to imagine ever constructing a bakery without implementing this design concept. New installations in most cases will provide a positive cashflow from startup, but there is also ample opportunity to retrofit existing plants with typical returns ranging from 15-25%. These retrofit costs can be offset to provide a quicker return when capital can be attributed due to a need to replace or upgrade existing boilers.

Heat recovery can be applied in facilities with or without oxidizers. Oxidizers have an advantage with increased availability of heat and centralized heat exchangers and normally have a lower installed cost, but recovery can also be implemented in facilities that don’t have oxidizers and currently plans are underway to do just that. This technology has also been explored in other industry sectors including Snack Foods with positive results.

Scott G. Houtz is President of Air Management Technologies, Inc. a mechanical design-build contracting and energy consulting firm located in New Columbia, PA. E-mail Scott Houtz