by Emily Newton
Industrial facilities are throwing profits away, leaking through deceptive cracks in the building as thermal losses. Runaway energy can cost manufacturers and machinery experts countless dollars before they realize the severity of the problem. Instead, companies can transform that waste into revenue by implementing energy capture technologies in utility and equipment systems. Every corner is an opportunity, with proven results and high returns on investment to justify up-front expenses.
Unrecovered Heat From Exhaust Stacks
Boilers, afterburners, furnaces and other heat-producing appliances in facilities radiate significant energy. Preventing it from escaping could be immensely lucrative, especially since 20%-50% of industrial energy intake is lost as exhaust gases and heat from hot equipment surfaces, among other sources. Companies may need to use multiple technologies across their workflows to maximize the value of escaping heat. Waste heat recovery units (WHRUs) are the ideal recuperators for these high-temperature devices.
They take exhaust gases and recycle them. One case study examined a steel plant that incorporated WHRUs. Analytics from connected software achieved a 60% efficiency when used for furnace reheating. Additionally, the process only took 1.48 hours to reach 315° Celsius, yielding a three-year payback period and saving $215,000 annually. WHRUs can also be made from heat-absorbing materials, such as ceramic, to capture additional residual heat and preheat air.
Discharge of Hot Process Water
From preserving foods during processing to manufacturing textiles, countless facilities need a continuous supply of hot water. Organizations lose monetary and utility resources by paying to warm and cool the water, in accordance with environmental discharge standards. Heat exchangers for water-to-water recovery are among the most optimal ways to achieve the temperatures required for processing without compromising efficiency or compliance.
Wastewater leaving the facility can still be deposited in the designated disposal areas. While it is on its path, heat exchangers can preheat the incoming process water the manufacturer needs for upcoming activities. Options like plate-and-frame and shell-and-tube heat exchangers work well alongside copper pipes because of their high thermal conductivity, enabling high recovery rates. Then, facilities like food processors can use it for repeat tasks, such as pasteurization, with a newly modified closed-loop model.
Poor Building Envelope and HVAC Inefficiency
Sometimes, heat escapes from the walls, open loading dock doors or through the ceiling. Insufficient building envelopes place additional pressure on heating and cooling systems, forcing them to compensate for the lack of insulation in the structure. Additionally, the extra strain on the HVAC equipment reduces its lifespan, increasing long-term maintenance and replacement costs. Smart insulation and building automation systems (BASs) are essential tools for identifying and addressing these inefficiencies.
Smart systems and adaptive building elements have the potential to create more circular facilities that reduce waste in even more domains than just heat. The planet produces more than two billion metric tons of solid waste annually, and visualizing areas for improvement using data provides the insights necessary for sustainable planning. BASs and smart sensors could inspire investments in insulation with higher R-values, destratification fans to regulate hot air or optimized loading dock doors to reduce open times.
Uncaptured Heat From Machinery and Air Compressors
Machines inevitably produce heat, especially when running at high speeds. In the era of autonomous production, equipment is running 24/7, sometimes without human oversight. Meanwhile, they emit a constant stream of squandered power, increasing cooling requirements year-round. Additionally, industrial staples such as air compressors can be major sources of thermal runaway and wasted radiant heat. Teams could be using the wrong type of compressor, with misaligned CFM and PSI for the application.
The solution is to replace outdated equipment with compressor heat recovery and cogeneration systems. The oil or water system in an air compressor is a valuable source of energy. Combined heat and power (CHP) equipment is another powerful option because it enables on-site power generation. Most industries generate heat with equipment like boilers, resulting in immense energy waste and ongoing utility costs to keep the process running. CHPs can achieve system efficiencies of over 80% while running continuously throughout the day and combining these processes into a single system.
Wasted Heat From Cooling Towers and Chillers
It seems antithetical, but the amount of energy wasted to reduce high temperatures in cooling towers is immense. As they chill, the heat is ejected away from them, floating into the atmosphere. Instead of letting the coolers and fans push the high temperatures away, teams can reuse them. Absorption chillers are the energy-conscious version of these essential industrial fixtures, nixing the need for electricity to power the system.
Absorption chillers can use any energy source, including waste heat from a CHP or other processes like solar cooling tech, to operate. This is a less expensive way to initiate essential cooling processes while reducing electricity demand. These savings are more helpful during summer, when prices can exceed budgetary comfort, especially during peak hours.
Product Cooling and Phase Change
In a similar way to cooling towers, which emit waste heat from their processes, many phase-change-based operations in facilities produce the same results. Cooling molten glass or processed plastics radiates heat, increasing temperatures in workspaces and warming the air. Industries can implement several strategies to mitigate these wastages, including radiant heat capture and an organic Rankine cycle (ORC) system.
An ORC system has been proven to deliver better performance than single-source alternatives by leveraging low-boiling-point liquids from waste heat sources. Incorporating this, along with other technologies, is ideal, especially when the output is not hot enough to work with conventional steam-based systems. Even hybrid setups yield results, improving power production by 44% with a low levelized cost of energy.
Driving Profitability Through Thermal Recovery
Facility stakeholders must plan to incorporate at least one of these strategies in the coming quarter if they have objectives to pad budgets while lowering carbon emissions. Uncertain grid stability, climate change stressors and fluctuating prices are all powerful motivators to install energy capture solutions sooner rather than later. The foresight will impact the business’s bottom line, while making it more innovative and resourceful as a competitor.
