World-renowned piano manufacturer Steinway & Sons is currently in the process of upgrading their aging kiln system at their American production facility in Astoria, Queens, New York. Because the high-quality pianos require tight tolerances for wood board moisture, the drying process for the raw wood purchased by the facility must be carefully controlled. The existing process uses the plant's original turn-of-the-century brick masonry kilns. Although the structures are sealed, insulated, and well maintained, the process is inherently inefficient. Low-pressure steam - both live steam injection and dry heat via a steam coil - is used for heat and provided by two natural gas-fired boilers. Steam injection is required to prevent too steep a moisture gradient from forming within the wood, which can produce "checking" or, cracks that occur on the ends and surfaces of the lumber, rendering the board unfit for use. Ventilation dampers are used to discharge the warm air and humidity periodically, resulting in high thermal losses. The cycle of steam injection and ventilation can last for as long as 5 weeks depending on the wood type and product specifications. The original kilns are being replaced by a partial vacuum kiln system manufactured in Warren, Vermont. The new modular system can fit on the back of a flatbed truck and is expected to reduce kiln-drying time to 4 to 5 days. The system creates a partial vacuum, reducing the heating requirements and increasing the speed of moisture removal. Heating inputs are so low that hot water can be used in place of steam for the drying process resulting in a step level increase in overall dry efficiency. Although the technology has been around for decades, it remains underutilized in the industrial market, with significant savings resulting from decreased energy use, increased product quality, and reduced labor. This presentation will provide a walk through the design, installation, and commissioning process of installing the new kiln system. It will focus on the "lessons learned" and challenges through each stage of the process, beginning with the retrofit options and decision tree leading to the partial vacuum system. The various design options and heat sources will also be discussed.
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