Steel production is a precise calculation of "temperature." From the 950°C charged billet to the 1180°C discharge and the furnace's extreme limit of 1300°C, every degree of heat carries high fuel costs. However, a large amount of waste heat is often discharged directly into the workshop – a clear signal that a professional waste heat recovery heat exchanger is missing. This not only worsens the working environment but also steadily erodes profits.
Recently, an internal report from the QSP hot rolling line of a major Vietnamese steel company disclosed a practical, quantifiable, and return-clear retrofit plan: upgrade the existing steel tunnel furnace heat exchanger system and add recovery units in areas currently without any recovery. This plan does not chase the "zero-carbon" slogan, but focuses on directly measurable fuel savings and investment returns – a field where Ukada heat exchanger manufacture brings deep expertise.
I. Pain Points: Temperature Drop and "Naked" Heat Discharge
The tunnel furnace at this steel plant originally had three sets of heat exchangers (recuperators), with Zone 7 responsible for preheating combustion air. Actual operating data showed that the combustion air temperature after the Zone 7 steel tunnel furnace heat exchanger averaged only 450–460°C, far below the design value of 530°C. With lower heat exchange efficiency, the system was forced to add extra LPG to compensate for the heat deficit.
Even more serious, the two Shuttle zones (Zone 6) had no heat exchange equipment at all. About 1000°C exhaust gas was discharged directly into the workshop, causing heat waves and high noise – buying expensive LPG on one hand, and throwing heat into the air on the other. This is exactly the scenario where a high-performance waste heat recovery heat exchanger becomes indispensable.
II. Solution: High Temperature Recuperator (HTR) + Modular Additions
For Zone 7: Upgrade the ordinary recuperator to a High Temperature Recuperator (HTR). Specific actions include:
Material upgrade: Replace all carbon steel heat exchange tubes (1.4512 / S275JHD) with high-grade stainless steel and redesign the internal flow path cross-section to improve heat transfer efficiency. As a professional Ukada heat exchanger manufacture, we prioritize metallurgical robustness for sustained 620°C+ operation.
Auxiliary system upgrade: The existing carbon steel combustion air piping cannot withstand long-term high temperatures above 500–550°C, so it must be replaced with high-temperature stainless steel piping; associated valves, seals, sensors, pressure transmitters, etc. are all upgraded to a grade withstanding ≥620°C.
Fan capacity check: Confirm whether the existing combustion fan can still meet the system air volume after the upgrade, avoiding insufficient fan capacity that would prevent system operation.
After the revamp, the combustion air temperature in Zone 7 will jump from 450°C to a target of 620°C. This leap brings fundamental thermodynamic benefits – better flame stability, lower fuel consumption, and more uniform furnace temperature distribution. Such a performance upgrade is exactly what you expect from a premium steel tunnel furnace heat exchanger designed and supplied by Ukada heat exchanger manufacture.
For the Shuttle zones: Adopt compact modular waste heat recovery heat exchangers integrated into the existing exhaust gas system. The flue gas is drawn from the existing damper on the furnace roof, passes through the new heat exchanger to transfer heat to the combustion air, and is then sent to the burners via piping. This design fully considers the moving load characteristics of the Shuttle zones – compact, vibration-resistant, and easy to maintain.
III. Benefits: Over 10% LPG Savings, 2–3 Year Payback
According to the project's expected assessment, after the revamp the entire tunnel furnace system can save more than 10% of LPG fuel. With LPG prices remaining high and volatile, the annual economic benefit is significant, and the total investment is expected to be recovered within 2–3 years. This rapid payback is a hallmark of a well-engineered waste heat recovery heat exchanger from reliable Ukada heat exchanger manufacture.
In addition to direct fuel cost savings, there are multiple hidden benefits:
Carbon deposit reduction: Higher combustion efficiency significantly reduces carbon black generation, thus lowering the damage rate of sensors and observation windows, extending equipment life.
Improved working environment: The Shuttle zones no longer discharge high-temperature flue gas directly into the workshop, markedly improving summer workshop temperature and air quality.
Lower carbon emissions: Saving 10% of LPG means an equal percentage reduction in CO₂ emissions – tangible "green competitiveness" under the increasingly stringent global carbon constraints.
IV. Implications: Steel Energy Saving Has Entered the Era of "Deep Waste Heat Recovery"
This technical document from the Vietnamese steel company actually provides a replicable model for the entire industry. It shows that without changing the main process or stopping production for major repairs, a significant improvement in energy efficiency can be achieved simply by upgrading and supplementing the steel tunnel furnace heat exchanger system.
Whether it is the upgrade from carbon steel to stainless steel tubes in Zone 7, or adding missing heat exchange modules to the Shuttle zones, the essence is the same logic – capturing waste heat from the exhaust gas stream and sending it back into the combustion system. This "on-site recovery, on-site reuse" model is more direct, has lower losses, and yields faster returns than long-distance district heating or waste heat power generation.
Why Choose Ukada Heat Exchanger Manufacture?
Suzhou Ukada Energy Saving Technology Co., Ltd. , with years of technical experience in Ukada heat exchanger manufacture, provides customized waste heat recovery heat exchanger solutions for steel tunnel furnaces and other high-temperature industrial applications. We make the investment return logic of every project clearer and more visible – from material selection to lifetime cost analysis. Contact Ukada to transform your waste heat into measurable profit.
