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Guides 2026-09-29

Flue Gas Waste Heat Recovery Systems (Boiler, Kiln & Converter)

Flue Gas Waste Heat Recovery Systems (Boiler, Kiln & Converter)

Flue gas from boilers, kilns, and converters leaves at 150–400°C — very high-grade heat that is traditionally lost up the stack. A flue-gas heat recovery system captures that energy and returns it to combustion air, process streams, or building heating. This guide covers the exchanger forms and how to specify them for a converter or furnace duty.

Why Flue-Gas Recovery Is High Value

Unlike low-temperature ventilation exhaust, flue gas carries dense, high-grade heat. Recovering even 15–25% of it from a 300°C stack can cut fuel use by double digits. Our waste-heat recovery methods overview frames the options; the real-world implementation (condensing, corrosion, white-plume) is in our flue-gas cooling and white-plume article.

Core Form: High-Temperature Welded Plate

Flue gas needs a core that survives heat and acid condensation. A high-temperature welded stainless-steel plate exchanger is the standard: stainless shrugs off the corrosion that destroys aluminum, and the welded construction handles thermal stress. For lower-temperature exhaust-air duties, a plate or heat-pipe core is enough. The material choice is in our material selection guide.

Converter / Steel-Furnace Duty

A converter off-gas recovery system pre-heats combustion or process air with the hot flue stream, improving furnace efficiency and cutting CO₂. Because the gas is hot and often particulate-laden, stainless construction plus an upstream dust stage is typical. The sensible-recovery math (effectiveness × temperature lift × mass flow) is in our efficiency reference.

What to Specify

Item Recommendation
Core Welded stainless plate (high temp)
Recovery Combustion-air / process pre-heat
Upstream Dust / particulate removal
Condensation Manage acid dew point (stainless)

Related

See our application library and selection guide.

Get a Flue-Gas Core

We build high-temperature stainless plate exchangers for boiler, kiln, and converter flue-gas recovery. Tell us your gas temperature, flow, and duty — contact +86 15753355505 for a matched quotation.

Engineering calculators

Run the numbers for your project: savings, sizing, psychrometrics and duct pressure.

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