Flue Gas Denitrification in Thermal Power Plants

Flue Gas Denitrification in Thermal Power Plants

In the flue gas denitrification system of thermal power plant, the finned tube heat exchanger is mainly used to recover the heat in the flue gas. During the denitrification process, the flue gas temperature is high, and part of the heat from the flue gas is transferred to other media, such as air or water, through the heat exchanger, to realize the recycling of heat and improve the energy utilization efficiency of the power plant.

Regulating flue gas temperature: A suitable flue gas temperature is crucial for the efficient conduct of denitrification reaction. The finned tube heat exchanger can accurately adjust the flue gas temperature according to the requirements of denitrification process to ensure that the flue gas enters the denitrification reactor at the optimal temperature range, thus improving the denitrification efficiency and ensuring the stable operation of the denitrification system.

Structural features

Finned tube: This is the core component of the heat exchanger, consisting of base tube and fins. The base tube is usually made of corrosion-resistant metal materials, such as stainless steel, to withstand the scouring and corrosion of high-temperature flue gas. The fins are fixed on the surface of the base tube by welding or mechanical connection, which increases the heat exchange area and improves the heat transfer efficiency. There are various shapes and sizes of fins, such as spiral fins, flat fins, etc. Different fin structures are suitable for different working conditions and heat exchange requirements.

Shell: Used to hold the finned tube, usually made of steel plate, with good sealing to prevent flue gas leakage. The shell is equipped with flue gas inlet and outlet, medium inlet and outlet and other interfaces to connect with other equipment in the denitrification system.

Tube plate: It is used to fix both ends of the finned tube to ensure the stability and sealing of the finned tube in the heat exchange process. The tube plate is welded together with the shell to form a whole structure.

Support structure: In order to ensure the stability of the heat exchanger during operation and to prevent the finned tubes from being deformed or damaged due to the flow of flue gases and thermal stresses, support structures, such as brackets, hangers, etc., are usually installed.

Working Principle

Heat transfer process: When the heat exchanger is in operation, the high temperature flue gas flows outside the finned tube, transferring heat to the outer wall of the finned tube. As the fins increase the heat exchange area, the heat can be more effectively transferred to the medium inside the base tube. At the same time, the medium inside the base tube absorbs heat in the flow process and the temperature rises, thus realizing the heat exchange between the flue gas and the medium.

Strengthen the heat transfer mechanism: the presence of fins not only increases the heat exchange area, but also changes the flow state of the flue gas and the medium, so that the fluid forms turbulence on the surface of the fins, which reduces the thermal resistance of the boundary layer and further improves the heat transfer efficiency. In addition, the fins are usually made of materials with good thermal conductivity, enabling rapid heat transfer from the flue gas to the medium.

Advantages

Highly efficient heat transfer: the special structure of finned tube greatly increases the heat exchange area and improves the heat transfer efficiency, which can realize a large amount of heat exchange in a small space and help to reduce the volume and weight of the heat exchanger.

Good corrosion resistance: The selection of suitable corrosion-resistant materials for the finned tube and shell can effectively resist the erosion of acids and other corrosive components in the flue gas, prolonging the service life of the heat exchanger and reducing the maintenance and replacement costs of the equipment.

Stable and reliable operation: reasonable structural design, good sealing and stability, able to withstand high temperature and high pressure flue gas environment, and maintain stable performance during long-term operation to ensure the normal operation of denitrification system.

Strong adaptability: the structure and parameters of finned tube heat exchanger can be flexibly designed according to different flue gas flow rate, temperature, composition and other working conditions, in order to meet the needs of flue gas denitrification system of various thermal power plants.