What is waste heat recovery and utilization?
Waste heat recovery and utilization refers to the process of collecting and reusing waste heat generated in industrial production or daily life (such as boiler exhaust gas, engine cooling water, etc.) through certain technical means. These waste heat usually exist in the form of thermal energy, which can be used for power generation, heating, cooling, or as a heat source in industrial processes through conversion.
Technical approach for waste heat recovery

heat exchanger
The most common waste heat recovery equipment is a heat exchanger, which achieves energy recovery through heat transfer between two different media. For example, the flue gas from industrial furnaces can be preheated by a heat exchanger to increase the combustion efficiency of the air or fuel gas entering the furnace.

Organic Rankine Cycle (ORC)
Organic Rankine cycle is a technology that utilizes low-temperature heat sources to generate electricity. Compared to traditional steam Rankine cycles, ORC can use organic working fluids with lower boiling
points, making it suitable for recovering energy from low-temperature waste heat.

Heat pump technology
A heat pump can "pump" the heat from a low-temperature heat source to a high-temperature location for use. Its working principle is similar to air conditioning, but the process is the opposite. In this way, waste heat can be upgraded into higher temperature thermal energy for heating or industrial processes.
Absorption refrigeration machine
Absorption refrigeration machines can utilize waste heat to drive refrigeration cycles, thereby providing cooling capacity. This technology is particularly suitable for situations with stable sources of waste heat, such as large industrial facilities.

Application cases of waste heat recovery
Steel industry: In ironmaking blast furnaces, a large amount of waste heat can be recovered through hot blast stoves to preheat the air entering the blast furnace, significantly improving energy efficiency.
Chemical industry: The heat emitted from chemical reactors can be recovered through heat exchangers for preheating raw materials or generating steam.
Power industry: The cooling water system of power plants can be equipped with heat exchangers to convert waste heat into residential heating or industrial heat.
Construction industry: Air conditioning systems in large commercial buildings can use heat pump technology to recover heat from condensers for hot water supply or auxiliary heating.

Challenges and prospects of waste heat recovery
Although waste heat recovery technology has significant energy-saving potential, it still faces some challenges in practical applications, such as high initial investment costs, complex system maintenance, and uneven technological maturity. However, with the continuous advancement of technology and policy support, the market prospects for waste heat recovery are vast. In the future, with the development of renewable energy and the construction of energy Internet, waste heat recovery will be more flexible and efficient, and become an important force to promote energy transformation and achieve the goal of carbon neutrality.