Seizing the Opportunity for Improved Energy Efficiency of an Existing Fluid Bed Incinerator

摘要

For water resource recovery facilities that use thermal oxidation (incineration) to manage wastewater solids there are often opportunities to recover energy from the combustion process to improve thermal efficiency, reduce operating costs and make significant contributions to overall plant sustainability. The Sewerage and Water Board of New Orleans (SWBNO) has implemented an innovative and cost effective project to capture energy from the exhaust of the fluid bed incinerator (FBI) at their East Bank Wastewater Treatment Plant (WWTP) to substantially reduce the use of fossil fuel during operation. When Hurricane Katrina devastated the WWTP it left both the FBI and a multiple hearth incinerator (MHI) badly damaged. The SWBNO elected not to repair the MHI but to increase capacity and improve the efficiency of the FBI by installing a drying system. With less water in the feed material there is more volume of the FBI available for combusting solids and fuel use is reduced with less water to be evaporated. The energy source for the drying system is heat recovered from the FBI exhaust gas created by the heat content of the biosolids released during combustion. Under typical conditions the drying system will reduce fuel use by 1.3 MW (4.3 million BTU/hr). With the drying system restoring solids processing capacity by increasing the capacity of the FBI, FEMA has approved funding for the dryer project, in lieu of repairs to the MHI, with approximately $4.8 million available for construction costs.