Abstract
This presentation provides an overview of the importance of Energy efficiency in steam systems, highlighting the need for it: the Decarbonization Path, various energy losses in steam systems, and opportunities to recover energy.
This presentation also includes explanations of various opportunities for heat recovery with a few global examples and case stories.
Now, the first question is
Why do steam systems matter?
Steam remains one of the most versatile and efficient heat transfer media. That is used in process heating in various industries like Chemical, Petrochemical, Oil & Gas, Refineries, Power generation, Food & Beverages, Sterilisation in Pharma, District heating, and humidification in HVAC and many other manufacturing industries like Automotive, Tires & rubber, Textile, Plastics, Surface treatment and Electronics plants.
Why Do We Require Energy Efficiency in Steam?
Steam systems account for 30% of global energy usage, and it is high-impact area for decarbonization and cost reduction. Southeast Asia (SEA) drives ~25% energy demand growth by 2035 (IEA). Fuel prices and CO2 emissions are rising, putting pressure on ESG and net zero targets. ASEAN aims to reduce energy intensity by 40% from 2005 levels. Energy Efficiency is the fastest, low-cost way to cut emissions and improve competitiveness.
The need for decarbonization:
There is no single or simple solution to decarbonise electricity, heat, chemicals and fuels – many technologies and solutions have a part to play across all sectors of the economy. Energy efficiency will be one of the main contributors, together with the build-out of renewable energy sources such as solar and wind, and the switch from fossil fuels to new energy carriers such as hydrogen and biofuels.
And for sectors where we cannot remove fossil fuels, in the so-called hard-to-abate sectors, we will need carbon capture technology. So, we are seeing a complete energy landscape in transformation.
Reaching the Paris Agreement requires a faster, broader and global implementation of sustainable solutions.
Energy efficiency is one of the main contributions to reaching the targets for the Paris agreement and is claimed to be our ‘first fuel’ for a decarbonised future.
According to IEA, Energy efficiency accounts for 40% of the potential carbon dioxide savings by 2040, the majority coming from the industry and buildings sector. But energy efficiency has an even more important role in the short term, as technologies are available today.
To be on track for Net Zero 2050, we need to halve our emissions by 2030, where energy efficiency could stand for 50% of these emission reductions. It represents approximately half of the abatement in the sustainable development scenario to 2030.
Steam systems in industry account for around 30% of manufacturing energy use and a significant fossil-fuel input. Improving steam‐system efficiency, therefore, delivers a big impact in both cost and CO₂ terms.
In countries across S.E.A., with growing industrial steam demand, improving steam-system efficiency is one of the fastest ways to reduce fuel use, emissions and cost.
Energy Losses in the steam system:
A complete steam plant consists of steam generation, distribution, utilisation, condensate recovery and various support systems like feedwater treatment, deaerators and start-up and safety systems. Modern boilers operate at 85 to 90% efficiency, but total system efficiency even drops to 60 to 70% means only that amount of fuel energy reaches the process. Now the question is, where does the energy go?
- Stack losses: 10 to 15%
- Blow down: 1 to 2%
- Condensate losses: 5 to 10%
- Flash steam venting: 5 to 8%
- Distribution and trap losses: 5 to 10%
Opportunities for heat recovery:
1. Feedwater and Fuel Preheating:
A boiler works best when the water and fuel entering it are already warm.
- If the feedwater is too cold, the boiler must burn more fuel to raise its temperature.
- If fuel oil is cold, it does not burn efficiently, causing higher emissions.
PHE can use recovered waste heat to preheat feedwater and fuel before entering the boiler. That improves boiler firing efficiency, reduces stack losses, enhances combustion quality and extends boiler life. Warm input led to a healthier, more efficient boiler.
Better heat balance = better efficiency + lower fuel cost
2. Condensate heat recovery:
When steam condenses after releasing heat in the process, the resulting condensate is still very hot, usually between 80 to 95 Deg C.
If this condensate is simply dumped down the drain or cooled before returning, all that heat is wasted.
But if we use PHE, we can transfer the heat from condensate into colder feedwater entering the boiler, so less fuel is burned, less fuel cost, reduces fresh water and chemical use, and protects the boiler from thermal shock.
3. Flash steam heat recovery:
When hot condensate moves from a high-pressure area to a lower-pressure area (like the return tank), some of it instantly re-evaporates. This is called flash steam.
Many factories still let this flash steam escape into the air, which is a major energy loss. With a PHE, we can condense the flash steam and use its heat for heating the other process streams, preheat feedwater.
Flash steam contains a large amount of latent heat that reduces visible steam plumes & greenhouse gases and improves overall steam system efficiency.
Flash steam recovery = capturing energy that would literally disappear into thin air.
Blowdown heat recovery: Boilers must remove a small amount of water regularly to reduce impurities like dissolved solids. The drained water is called blowdown, and it exits the boiler at very high temperature. Without recovery, that heat goes straight to waste.
A PHE can be used to transfer the heat from blowdown water to cold make-up water entering the system. This lowers fuel demand and improves boiler efficiency. The blowdown heat recovery prevents energy loss in the blowdown. Reduces freshwater heating demand and makes the operation more economical. Blowdown heat recovery turns a waste function into a cost-saving one.
Boiler Protection: In a steam system, water continuously circulates through pipes, tanks and equipment. Along this journey, water can pick up unwanted contaminants such as rust from ageing pipes, sand, dirt and debris, CaCO3 scale, Oxygen that accelerates the corrosion and particles from non-oxygen barrier tubing in radiant floors. If these impurities reach the boiler, they can damage and block the heat transfer surfaces in the boiler.
A PHE acts like a protective wall. It isolates the boiler from dirty or chemically unstable water circuits. Only clean, properly treated water enters the boiler. This means boilers stay healthy, efficient and safe.
The Silent killer – Calcium Carbonate: Question is, why does scale form? When water is heated inside a boiler, dissolved minerals like calcium plus bicarbonate react they turn into hard CaCO3 scale. This scale sticks to boiler tube surfaces and forms an insulating layer. The consequences are higher fuel consumption. The rule of thumb says that a 0.3 mm thickness of CaCO3 increases 10% fuel consumption, and 1.0 mm thickness increases approximately 30% of fuel consumption. It means boilers meant to consume 100 units of fuel may now require 130 units.
Scale also causes overheating of tubes, and they get ruptured. It increases stack temperature and increases waste heat, soa higher CO2 output higher environmental penalty.
A PHE reduces scale formation on the boiler side by maintaining stable, well-treated feedwater.
Debris & Corrosion – The Mechanical Threats: Particles and oxygen cause:
Internal damage: rust eats steel inside the boiler.
Reduced flow: sludge deposits block passages.
Pump strain: More power needed to circulate water
Hot spots: Poor water contact, tube overheating, this leads to safety risks, unexpected shutdowns, Expensive repairs, more energy needed to push water through the system.
A PHE blocks these contaminates from ever reaching the boiler.
Static Pressure & System separation:
Some heating circuits operate with variable pressure (like floor heating or process loads). If it is without protection, then pressure swings damage boiler seals and internal structures. Air can migrate, and corrosion accelerates. Water chemistry becomes unstable and more scaling risk.
A PHE hydraulically separates circuits, so the boiler always operates in a stable, controlled environment.
Stability = Higher efficiency + Longer life + Lower Cost
Heat recovery from deaeration valve:
In the process of dearation to remove dissolved gases (mainly Oxygen & CO2) from the feed water before it enters boiler. These gases are vented out through the deaeration valve at top.
The small amount of steam is continuously vented through dearetion valve to carry away the unwanted gases.
In one of the cases for a medium-sized boiler 25 kg/hr. It seems tiny.
25 kg/hr X 24 h/day X 365 days = 219,000 kg = 219 tons/ year so appx. 200 tons of steam lost per year simply fromthe dearator.
If we convert that ~150 MWh of energy per year, and equal to 200 m3 of treated make-up water that needs to be replaced.
That is the energy you already paid for fuel, water treatment, chemicals added that go into vent. A small PHE can recover heat from vent steam. PHE condenses the vent steam into water. The condensate is collected and returned to the feedwater tank. The heat is transferred to cold make up water.
Case Story 1: Flash steam heat recovery from India
Steam Boiler 10 TPH 155 Deg C with 5% flash steam 500 kg/hr @105 Deg C
Energy Savings: Recovered to process water 313 kW
Running hours 4,380 h/y
Cost of Natural Gas 0.05 €/kWh (4.4 INR)
Customer savings: 67,560€/year (5,940,000 INR)
Fuel costs: 313kW x 4,380 h/y x 0.05 €/kWh
Carbon emission: 1,081,000 kg Co2/year
Return on investment ROI = 2.7 months
Total investment 15,000 €
(Alfa Laval HEX + flash drum + installation & piping) (1,320,000 INR)
Case Story 2: Safe Sterilization by high-speed heating & Cooling, China
Rapid Heating:
Before sterilisation shortens the entire sterilisation cycle, reducing the survival time of microorganisms in a non-sterilisation temperature range, and minimising the risk of microorganisms developing heat-resistant mutations.
Rapid Cooling:
Rapid Cooling is required to protect the material and performance of the sterilised item. It prevents the ageing and deformation of devices caused by long-term exposure to high temperatures, making sure that the quality and service life of critical devices is maintained.
Alfa Laval PHEs heat and cool the solution within eight minutes for small cabinets and fifteen minutes for large cabinets.
Design criteria
Fluid properties:
Heating: water / steam
Cooling: water / water
Temperatures:
Heating: Process water 20° to 121°C, Steam at 151 Deg C
Cooling: Process water 121° to 40° or 60°C
The temperature of the cooling water differs at each installation.
Type of heat exchangers:
TS6M, T6; T10, TS 20 and CB units
Material choice: AISI 316 & EPDM gasket
Correct heat exchanger for heat recovery: PHE Vs S&T
Thermal Fatigue and Efficiency:
Thanks to the elasticity of the gasket, there will be no thermal fatigue problems in the plate pack. A close temperature approach is possible in a PHE.
Temperature efficiency =
Conclusion and Recommendations:
- Steam systems are vital and energy-intensive.
- Energy Efficiency is the fastest path to decarbonization.
- Every part of the steam cycle offers recovery opportunities.
- Boiler protection is equal to energy protection.
- Small losses add up to big waste.
- Recommend thinking about Energy flows, not just equipment.
- Measure, Monitor and question losses.
- Integrate heat recovery early in the design
Lastly, Energy Efficiency is not a product, it’s a mindset. Be curious, be efficient and let no energy go to waste.
Presenters:
Himanshu Sheth
Sr. Global Business Development Manager,
Alfa Laval Technologies AB, Sweden
FAQs
- Stack losses: 10–15%
- Blowdown losses: 1–2%
- Condensate losses: 5–10%
- Flash steam venting: 5–8%
- Distribution & trap losses: 5–10%
- Feedwater & fuel preheating to reduce boiler firing and stack losses
- Condensate heat recovery to return valuable heat and reduce fresh-water demand
- Flash steam recovery to capture latent heat that is otherwise vented
- Blowdown heat recovery to reclaim high-temperature blowdown energy
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