OXIDIZER/OVEN HEAT RECOVERY SYSTEMS BAKERIES

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 with several successful installations throughout the United States and Canada.  Today if you were to visit one of these plants you would find no boiler room, but you would find an innovative heat recovery system supplying proofers, fermentation rooms, and other end uses with more than enough heat to satisfy their load requirements. 

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 is accomplished by combining our expertise in managing the efficient distribution and control of the energy source with capturing  the generated waste heat from the oven(s) or oxidizer exhaust streams which results in complete system with guaranteed savings. 

The system can serve various points of usage including proofers, fermentation rooms, plant water heating, feedwater, CIP, space heating, etc. System operation is accomplished by utilizing heat from the oven exhaust stream that passes thru the plants oven(s) and / or 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 with a footprint about double the size of a residential air conditioner 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. 

Central hot water distribution loop provides heating from the recovery system to end uses at a temperature between 200º-210ºF, and by incorporating a combination of compressed air atomization and high-pressure humidification systems to proofers and fermentation rooms 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. 

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 two line plant savings can be in excess of $60,000 per year. 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 with new installations the cost is completely defrayed by eliminating the conventional steam boilers so savings begin immediately providing a positive cash flow. 

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 is a major driving force behind this type of project which 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 but recovery can also be implemented in facilities that don’t have oxidizers and still satisfy production heat load requirements. 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 Lewisburg, PA. E-mail him at scott.houtz@airmanagement.com.