BACKGROUND
Boilers are employed in over 100,000 industries in the U.S. alone for a multitude of applications. These may entail supplying steam to remote locations from a central steam plant (District Heating,) or may simply consist of a single, dedicated boiler. In all cases, regardless of the type of fuel used, boiler efficiency is critical to operating costs and environmental regulatory compliance.

In an effort to maximize the use of energy, several approaches have been used to capture heat wasted in flue gas. Economizers and air heaters are the most common examples. An economizer adds heat to the boiler feed-water (BFW) after it leaves the de-aerator and before it enters the boiler. Heat captured from the flue gas directly raises the boiler efficiency.

SOLUTION
Direct Contact LLC (DCLLC) Heat Recovery Systems capture wasted heat (both sensible and latent) by utilizing cool BFW makeup and a unique “direct-contact” process. This approach extracts much more heat from hot flue gas than is captured by an economizer alone. A DCLLC Heat Recovery System is designed to be “transparent” to boiler operation, in that it can be taken off-line without affecting production processes. The Heat Recovery System can be used with or without an economizer or air heater.

DIRECT BENEFITS
The overall heat efficiency of your system can be increased significantly (as much as 6%) by using a DCLLC Heat Recovery System. The more make-up water required, the more efficiency our systems provide. For example, a DCLLC system installed on a typical boiler (already fitted with an economizer) burning natural gas at 15% excess air and returning 50% condensate would realize an increase of approximately 3% efficiency. The same system, with zero condensate return, would increase boiler efficiency by 6%. (See District Heating.) Energy savings quickly add up to offset the purchase and installation costs of the DCLLC Heat Recovery System and contribute to the facility’s long-term profitability.

Where there are nearby water heating requirements (e.g., laundry, showers, floor radiant, miscellaneous industrial, etc.), recovered heat can be used for these requirements to provide additional justification for such a system. A supplementary benefit is that this technology also condenses the water from combustion and generates a positive net water flow to the system, since the fuel stream is not generally considered a water source.