The economizer is a device installed in the lower part of the flue gas duct of a boiler for recovering the residual heat of the exhausted smoke. It heats the boiler feed water into the heated surface of the saturated water under the pressure of the steam drum as it absorbs the high-temperature smoke. The heat of the gas reduces the exhaust temperature of the flue gas, saves energy and improves efficiency, so it is called an economizer.
Steel tube economizers are not subject to pressure limitations and can be used as boiling type, typically made from carbon steel tubes with an outer diameter of 32-51 mm.
Sometimes use finned tube to improve heat transfer.
The economizer is mainly applied to the industry and gradually spreads to agriculture and some related industries and commerce.
Features of Finned tube economizer:
1. The H-shaped finned tube is used as a heat exchange element, which has high heat transfer efficiency, compact structure, less dust accumulation, good anti-wear performance and good overall steel strength, and eliminates waste heat recovery.
2. The flue gas import adopts the patented design and manufacturing of Xi’an Jiaotong University, and the smoke is evenly distributed, which effectively reduces the wear.
3. It is made of sulfuric acid-resistant corrosion steel in the low-temperature section of the contact parts with the flue gas, and the smoke is evenly distributed, which effectively reduces the wear.
4. Maintenance and maintenance clearances (usually 800-900mm) are left between the high temperature section and the low temperature section to facilitate overhaul;
5. Modular design method, convenient and reliable installation, simple operation and high efficiency;
Advantage of Finned tube economizer:
1. Wear-resistant, can increase the wear life 3-4 times.
2. Less ash
The reason why the H-shaped fins are little dusty is as following:
1. The H-shaped fins are welded to the sides of the tube that are not easily covered with ash,
and the airflow flows straight. The airflow direction is parallel to the fins, and the fins
are not easy to accumulate ash.
2. There is a gap of 4-10mm in the middle of the H-shaped fins, which can guide the airflow
to sweep the pipe fins.
3. Extensive heating surface can greatly reduce the smoke temperature
The heating surface is fully expanded, and the heating surface can be increased by 2-3 times, which can greatly reduce the exhaust temperature.