Waste Heat Power Generation from Cement Kiln Exhaust Using Finned Tube Heat Exchangers

Waste Heat Power Generation from Cement Kiln Exhaust Using Finned Tube Heat Exchangers

During cement production, rotary kilns and cooler grate systems emit large volumes of medium-to-low temperature exhaust gases (typically 300°C–400°C). The waste heat power generation system recovers thermal energy from these exhaust gases, converting it into electricity to achieve cascading energy utilization. The system primarily consists of:

AQC Furnace: A heat exchanger that recovers high-temperature exhaust gases from the middle section of the cooler grate.

SP Furnace: Heat exchanger recovering exhaust gas from the kiln tail preheater.

Finned tube heat exchangers serve as the core heat transfer surfaces for these boilers.

Working Principle

The entire system follows the Rankine cycle:

Heat Recovery: Cement kiln exhaust gas flows over the outer surface of the finned tube heat exchanger.

Heat Transfer: Heat from the exhaust gas is transferred through the fins and tube walls to the working fluid (water/thermal oil) circulating inside the tubes.

Power Generation: The heated working fluid vaporizes into high-temperature, high-pressure steam, driving the turbine to rotate and thereby powering the generator to produce electricity.

Exhaust Discharge: The cooled exhaust gas (typically reduced to 90°C-150°C) is discharged from the system.

Why Choose Finned-Tube Heat Exchangers? (Core Advantages)

Cement kiln exhaust gas is a classic “high-flow, low-grade, high-dust” heat source. Finned-tube heat exchangers excel in addressing these challenges:

Overcoming Gas Heat Transfer Bottlenecks: With extremely low heat transfer coefficients on the exhaust side, fins dramatically increase the heat transfer area, enabling efficient heat exchange within compact equipment dimensions.

Handling High Flow Rates: Massive exhaust volumes demand extensive heat transfer area. The compact fin-tube design is the only economically viable solution meeting this requirement.

Reducing Material Costs: Compared to plain-tube heat exchangers, fin-tube units save substantial metal materials for equivalent heat transfer capacity, lowering manufacturing costs.

Successful application of finned tube heat exchangers in cement kiln waste heat power generation delivers:

Substantial power generation revenue: Converting discarded thermal energy into electricity meets approximately 20%-30% of the cement plant's power demand, drastically reducing purchased electricity costs.

Enhanced energy efficiency: Achieving a qualitative leap in overall energy utilization for cement production.

Environmental emissions reduction: Under identical production conditions, it decreases fossil fuel consumption and corresponding CO₂ emissions.

Lower flue gas temperature: It alleviates thermal loads on downstream dust removal equipment (e.g., baghouse dust collectors), extending their operational lifespan.