Finned Tube Radiator for Paper and Alkali Furnace Supporting Primary and Secondary Air Heaters

Finned Tube Radiator for Paper and Alkali Furnace Supporting Primary and Secondary Air Heaters

In the paper industry, the alkali recovery furnace (alkali furnace) is used to process the black liquor produced in the pulping process, and recover alkali and heat energy by burning the black liquor. The primary and secondary air heaters are important components of the alkali furnace, used to heat the air entering the furnace chamber and improve the combustion efficiency.

Primary air: Used to provide the basic oxygen required for combustion.

Secondary air: Used to supplement the combustion, ensuring complete combustion of the black liquor and reducing pollutant emissions.

Finned tube radiators increase the heat transfer area by adding fins outside the base tube to improve the heat transfer efficiency. The working principle is as follows:

Flow of hot medium: High temperature flue gas or steam as hot medium flows inside the finned tube.

Heat transfer: the heat of the hot medium is transferred to the surrounding air through the tube wall and fins.

Air heating: Cold air passes through the outside of the finned tube, absorbs heat and then increases in temperature to form hot air to be sent to the alkali furnace.

Application in paper making and alkali furnace

Primary air heating

Through the finned tube radiator, high temperature flue gas or steam is used to heat the primary air to improve the combustion efficiency.

The temperature of the heated primary air is usually 150°C-250°C.

Secondary air heating

The secondary air is heated by finned tube radiator to ensure complete combustion of black liquor and reduce pollutant emission.

The temperature of the secondary air after heating is usually 200°C-300°C.

Waste heat recovery

Utilize the high temperature flue gas discharged from the alkali furnace to heat the primary and secondary air through the finned tube radiator to realize waste heat recovery and reduce energy consumption.

Advantages of finned tube radiator

Efficient heat transfer: the finned design greatly increases the heat transfer area and improves the heating efficiency.

Uniform temperature: through the reasonable arrangement of the radiator to ensure uniform temperature distribution of the hot air.

Energy saving and environmental protection: efficient heat utilization reduces energy waste and lowers operating costs.

Compact structure: small volume, easy to install and maintain.

High-temperature and corrosion-resistant: High-temperature and corrosion-resistant materials (such as stainless steel or carbon steel) can be selected according to process requirements.

Design considerations

Heat medium selection: high temperature flue gas or steam as heat medium, need to select the appropriate medium and temperature according to process requirements.

Fin parameters: according to the heating requirements to select the fin height, spacing and thickness, optimize the heat transfer efficiency.

Arrangement: The radiator should be evenly arranged in the duct to ensure uniform temperature distribution of the hot air.

Air flow: Enhance air flow through fan to improve heating efficiency.

Corrosion resistance: Select corrosion-resistant materials according to the process environment to extend the service life of the equipment.

Convenience of maintenance: the design should be considered easy to clean and maintain, to prevent the accumulation of dust or clogging affect the efficiency of heat transfer.