Enameled Tube Air Preheater | Special Equipment for Boiler Flue Gas Waste Heat Recovery

The enamel-lined tube air preheater is a tubular waste heat recovery device that uses a high-temperature sintered acid-resistant enamel layer on the outer/inner wall of steel tubes as the heat exchange element. It is specifically designed for high-sulfur, high-ash flue gas conditions in coal-fired, biomass, and waste incineration boilers. It utilizes the waste heat from the high-temperature flue gas at the boiler tail end to heat the combustion air entering the furnace, significantly reducing coal/biomass fuel consumption. Simultaneously, it addresses the industry pain point of low-temperature acid dew point corrosion, making it the most cost-effective waste heat recovery device for boilers with highly corrosive flue gas.

Work Process

1. High-temperature boiler flue gas (160~400℃) flows through the tubes, and heat is transferred through the enamel-lined tube wall to the cold air outside the tubes;

2. Room-temperature fresh air flows horizontally across the tube bundle, absorbs heat, and is then sent into the boiler furnace for combustion;

3. After cooling, the flue gas enters the dust removal and desulfurization equipment; the preheated hot air improves combustion efficiency and reduces exhaust heat loss;

4. The dense enamel layer isolates sulfur oxides in the flue gas, preventing condensation on the tube walls and acid corrosion.

Core Structural Components

1. Heat Exchanger Tube Bundle: 20# seamless steel tubes, double-sided high-temperature enamel enameled, coating thickness 0.3~0.5mm, pinhole-free;

2. Tube sheet, shell, flue gas inlet/outlet ducts, hot air ducts;

3. Reserved soot blowing port, maintenance port, and expansion joint to accommodate boiler thermal expansion and contraction;

4. Available in vertical and horizontal structures; the vertical structure occupies less space, while the horizontal structure offers more convenient maintenance and soot cleaning.

Core Advantages (Core Value of Boiler Waste Heat Recovery)

1. Superior resistance to low-temperature acid corrosion, significantly extending service life

Coal and biomass combustion produces SO₂ and SO₃. Below the acid dew point, the flue gas will condense sulfuric acid, corroding ordinary carbon steel tubes. The enamel glass coating completely isolates the tubes from acidic media, extending their service life by 3~5 times compared to ordinary carbon steel tube preheaters, avoiding frequent tube bundle replacements and boiler shutdowns for maintenance.

2. Stable Heat Exchange, Significant Energy Saving and Consumption Reduction

The enamel layer has extremely low thermal conductivity and minimal heat exchange efficiency degradation; hot air temperature can reach 90~280℃, increasing the overall boiler thermal efficiency by 7~14%, saving fuel by 9~17%, and quickly recovering equipment investment.

3. Smooth Tube Walls, Less Prone to Ash Accumulation and Clogging

The dense and smooth enamel surface makes it difficult for fly ash and tar to adhere, reducing the frequency of soot blowing, lowering the power consumption of induced draft fans and forced draft fans, and maintaining stable waste heat recovery capacity over the long term.

4. Low Overall Operating Costs

- Purchase price is significantly lower than heat pipe and all-stainless steel plate preheaters;

- Tube bundles can be replaced individually without overall disassembly, resulting in low maintenance labor and parts costs;

- Reduces heat loss caused by corrosion and air leakage, reducing desulfurization agent consumption.

5. Adaptable to harsh flue gas conditions

Suitable for high-sulfur, high-dust flue gas environments such as circulating fluidized bed boilers, biomass boilers, coal-fired hot water/steam boilers, and hazardous waste incinerators.