Most industrial processes rely on equipment such as furnaces, kilns, heaters, boilers, internal combustion engines, and gas turbines. These systems typically combust fossil fuels like coal, oil, or natural gas. During this combustion, only a portion of the atmospheric oxygen is utilized, with the remaining gases released as exhaust flue gases.
These flue gases absorb a significant amount of the energy generated – often between 20% and 50% of the total energy from fossil fuel combustion. Their temperatures typically range from 150°C to 400°C. This heat, contained within the flue gas, is often wasted and lost to the atmosphere.
It is possible to recover this wasted heat through technological intervention and convert it into usable power. When flue gas temperatures exceed 300°C, the heat can be efficiently recovered using a Heat Recovery Steam Generator (HRSG) to generate power via a conventional Rankine cycle power plant.
However, conventional Steam Rankine Cycle power plants may not be feasible if the flue gas temperature is below 250°C to 300°C. Furthermore, certain industries, such as petroleum refineries, have liquid process streams with temperatures ranging from 120°C to 250°C that require cooling to approximately 60°C before storage. This highlights a critical need for advanced technologies capable of capturing this valuable low-grade heat from both flue gases and liquid streams.
At First ESCO, we offer proprietary, patented technology to recover this low-grade heat and convert it into power using Organic Rankine Cycle (ORC) power systems. To learn more about our innovative technology and discover how you can benefit from low-grade heat recovery, please contact us.
Additionally, if you would like to calculate the potential revenue from your waste heat recovery system using ORC, we have developed a Waste Heat Recovery Calculator that can assist you in estimating the financial benefits of implementing our ORC systems.
First ESCO's presentation on WHR-ORC and Thermal Energy Storage
Beyond continuous heat streams, we also provide advanced technologies for Thermal Energy Storage, particularly for intermittent heat sources. A prime example is heat recovery from Electric Arc Furnaces (EAF) in steel melting. While off-gas temperatures from EAFs can reach around 1400°C, the heat availability is intermittent, as steel is melted in batches (known as "heats"). Currently, due to this intermittent nature, off-gases are often cooled using energy-consuming forced draft heat exchangers, rather than recovering their valuable heat.
Our Thermal Energy Storage solution is ideally suited for these scenarios. It allows for the recovery and storage of high-temperature heat during a "heat cycle" when hot gas is available. This stored heat can then be utilized continuously, even when no off-gas is being produced. This presents a significant opportunity for the steel industry to recover valuable heat, generate power, and thereby reduce their specific carbon emissions. This, in turn, helps mitigate potential disadvantages arising from regulations such as the Carbon Border Adjustment Mechanism (CBAM) imposed by European customers.