Finned Tube Heat Exchanger for Drying/Kiln Exhaust Waste Heat Recovery

Finned Tube Heat Exchanger for Drying/Kiln Exhaust Waste Heat Recovery

The finned tube is utilized to increase the heat exchange area so that the high temperature exhaust gas from the drying/kiln furnace flows through the tube or shell section of the finned tube heat exchanger, while the air, water or other media that needs to be preheated flows through the other side. Through the thermal conductivity of the tube wall and fins, as well as the convective heat transfer between the fins and the fluid, the heat in the exhaust gas is transferred to the heated medium, thus realizing the waste heat recycling and improving the efficiency of energy utilization.

Fin design

There are various types of fins: straight fins, spiral fins, serrated fins and so on. Straight fins are simple in structure, easy to manufacture, and are suitable for general heat transfer occasions; spiral fins can increase more heat transfer area in a limited space to strengthen the heat transfer effect, and are commonly used in high temperature and high flow rate exhaust environment; serrated fins further improve the heat transfer coefficient by increasing the disturbance of the fluid, and are especially suitable for working conditions with high requirements on the heat transfer efficiency.

Material selection: according to the exhaust temperature, corrosivity and other characteristics, fin material can be selected from carbon steel, stainless steel, aluminum alloy and so on. In the high temperature, non-corrosive environment, carbon steel fins lower cost and can meet the requirements; for corrosive exhaust, stainless steel fins have good corrosion resistance and oxidation resistance; and aluminum alloy fins have the advantages of light weight, good thermal conductivity, suitable for some of the weight of the requirements of the occasion.

Tube Selection

High Temperature Resistance: Due to the high temperature of the exhaust gas from the drying/kiln furnace, the tubes need to have good high temperature resistance. Generally, seamless steel pipe can be used. For extremely high temperature, special materials such as alloy steel pipe or ceramic pipe can be used. Alloy steel pipe has high high-temperature strength and oxidation resistance, can work at high temperatures for a long time and stable; ceramic pipe has excellent high-temperature resistance, corrosion resistance, but need to pay attention to its brittleness is large, in the installation and use of the process to prevent collision.

Corrosion resistance requirements: If the exhaust contains acidic gases, water vapor and other corrosive components, the pipe needs to have good corrosion resistance. For example, when dealing with exhaust gas containing sulfur dioxide and other acidic gases, acid-resistant stainless steel pipe or steel pipe lined with anticorrosive materials can be used to extend the service life of the heat exchanger.

Advantages

High efficiency and energy saving: It can effectively recover a large amount of waste heat from drying/kiln exhaust and use it to preheat air, water or other media, reducing energy consumption and lowering production costs.

Compact structure: the design of finned tube makes the heat exchanger have a large heat exchange area in a small volume, saving installation space, suitable for drying / kiln places with limited space.

High stability: the use of high-quality materials and reasonable structural design, can withstand high temperature, high pressure and corrosive and other harsh working conditions, stable and reliable operation, low maintenance costs.

Strong adaptability: According to different drying/kiln process requirements and exhaust parameters, the structure, size and material of the heat exchanger can be flexibly designed to meet diversified waste heat recovery needs.

Application Notes

Anti-corrosion measures: For the corrosive components in the exhaust gas, in addition to selecting suitable corrosion-resistant materials, measures such as coating protection and corrosion inhibitor treatment can also be taken. For example, coating the heat exchanger surface with high-temperature resistant anti-corrosion coating can effectively isolate the corrosive gas from the metal surface and slow down the corrosion rate.

Anti-dust accumulation and ash removal: exhaust gas may contain dust, particles and other impurities, easy to accumulate ash on the surface of the fins and tube walls, affecting the heat transfer effect. Reasonable airflow channels and flow rates can be set to reduce the possibility of ash accumulation. At the same time, equipped with effective ash-cleaning devices, such as pulse blowing ash-cleaning system, mechanical vibration ash-cleaning device, etc., regular ash-cleaning operation.

Thermal expansion compensation: Under high temperature working conditions, finned tube heat exchanger will experience thermal expansion. Therefore, it is necessary to design a reasonable thermal expansion compensation structure, such as the use of bellows, expansion joints, etc., in order to absorb the displacement generated by thermal expansion, to prevent equipment damage due to thermal stress.

Operation monitoring and maintenance: install temperature, pressure, flow and other monitoring instruments, real-time monitoring of the heat exchanger's operating parameters, and timely detection of abnormalities. Regular inspection and maintenance of the heat exchanger, including checking the damage of fins, corrosion of tubes, sealing performance, etc., and timely replacement and repair of damaged or aging parts.