Heat Recovery System Design for the Renderer & Biowaste System
JBMR Consulting was tasked with designing a heat recovery system for the Renderer and Biowaste System (RBS) of the (). This report provides the needed background on the project, discusses the process for selecting the design and how it was optimized, presents the final design, and concludes with future work recommendations. The performs vital research on infectious diseases. The RBS is a key part of their operations, as it collects the effluent from containment Levels 3 and 4, sterilizes it, and then discharges it to the city’s sewer system. The RBS process uses an excess amount of water, measured at approximately 4373 kg per cycle, and it takes around 2 hours to heat up the effluent. Our main goals were to minimize the cooling water used, to reduce the effluent heating time, and for our design to be maintenance-friendly and safe. A preliminary concept for the final design was selected during Phase 2 of this project. However, after further research and consultation with the, this concept was altered to be more feasible and easier to implement. Each heat exchanger and the system that connects them were optimized through research and analytical calculations to meet the needs of the. The final design that resulted from these is as follows. A 0.75 hp pump pumps water at a rate of 32.5 gpm through schedule 40 6-inch lines from a 1000-gallon reservoir. The water first passes through the three discharge heat exchangers in series. These are 54-inch long tube-in-tube heat exchangers with 6-inch inner tubes and 8-inch outer tubes connected directly to the outlets of cookers 1 and 2, and the combined outlet of cookers 3 and 5. The water draws heat from the discharging sterilized effluent. The water next passes through the open-tank heat exchanger within the active hot well. This consists of five parallel coil panel heat exchangers with 0.75-inch tubes with 16 passes each. The open-tank heat exchanger array draws heat from the sterilized effluent-water mixture within the hot well at all times. The now heated water goes through the custom-designed parallel tubes heat exchanger located at the inlet line to the cookers. The heated water preheats the unsterile effluent before it enters the cookers. After going through the inlet heat exchanger, the water is further cooled through a radially finned return line and is deposited back into the reservoir to be recirculated. This system successfully saves 1265.5 kg of water and 5 MJ of heating energy per cycle. All components can be easily installed and removed for maintenance, and leak detection methods are incorporated for safety.