Abstract:
The following report has been compiled to provide a guideline for designing a waste heat recovery and transportation system in an industrial facility. The overwhelming availability of waste heat in the United States demonstrates the inefficiencies and the wasteful practices currently in the industrial sector. These inefficiencies are estimated to be anywhere between 20% and 50% of the total energy purchased and a large portion of this energy is contained in exhaust gas from combustion processes at temperatures below 450°F. This wasted energy does not only cost the manufacturer extra money to operate, but adds an additional environmental impact. This impact is not just from excess CO2 production but from a steady source of high temperature exhaust gas flowing into the atmosphere. To assist in recovering and determining the possible uses for this recovered energy, background information and recommended uses for waste heat recovery equipment are given. Additionally, thermal heating fluids and phase change materials which can be used to transport and store this recovered energy are discussed. A sample design of this energy transportation system, along with end uses is provided to demonstrate the method of determining the possible energy and cost savings impact which are estimated to be 14,700 MMBtu/year and $120,000/year respectively. This system design includes recovering energy from 485°F exhaust air flowing at 4,050 cfm and distributing this energy throughout the plant to perform several different tasks. These tasks include space heating, domestic hot water production, maintaining a minimum temperature in glue baths, powering an absorption chiller and preheating boiler feed-water. The remaining energy is then stored in two thermal storage tanks, one for the sensible heat exchanger loop and one for the condensing economizer loop. The design shows a rough implementation cost based on the material and labor to be just over $323,000. These values can be used to demonstrate a typical payback period of 2.7 years. The information provided throughout the report is intended to inform the reader of the overall impacts of wasted heat energy while providing options and methods for recovering this wasted energy.
