It’s a question we hear more and more: “Can I reduce the pressure of my steam boiler?”
The short answer is, “Yes, you can”—but the real question is: should you? While reducing boiler pressure might seem like a simple way to lower energy consumption and CO₂ emissions, the reality is more complex. Let’s explore the implications, dispel some myths, and highlight better strategies for optimising your steam system, all with the support of Spirax Sarco’s Advance Consulting service.
Why Consider Reducing Boiler Pressure?
The primary drivers behind this question often include:
- Lower gas consumption
- Reduced carbon emissions
- Compliance with safety or insurance requirements
On the surface, it seems logical: if you’re generating steam at a high pressure (e.g., 10 BarG) but only need 2 BarG at the point of use, why not generate steam at 5 BarG instead? You’d burn less fuel, right?
Not necessarily. The latent heat content of lower-pressure steam is also reduced. This means your boiler might need to produce a greater mass of steam to meet process demands, potentially offsetting any perceived savings.
Why Reducing Boiler Pressure May Cause More Problems
Here’s why reducing your boiler pressure might not be the best move:
1. Reduced Resilience
At higher pressures, boiler water contains more sensible heat, acting as an energy buffer during periods of high demand. Lowering the pressure reduces this stored energy, potentially leading to:
- Steam starvation during peak demands.
- Increased boiler cycling, reducing efficiency and longevity.
2. Infrastructure Mismatch
Your current steam system is likely designed for the original pressure and flow rate. Reducing pressure can cause:
- Higher steam velocities: Steam will need to move faster to deliver the same mass, increasing wear and tear.
- Erosion: Faster-moving steam carries moisture, rust, and scale, damaging valves, meters, and pipework.
- Water hammer: High-speed condensate increases noise, vibration, and risks of pipe failure.
3. Safety and Control Issues
- Safety valves are sized for a specific pressure/volume relationship. Lowering pressure may render them ineffective or non-compliant.
- Control systems like pressure-reducing valves and flowmeters become misaligned with the new pressure, reducing accuracy and reliability.
4. Poor Steam Quality
Lower-pressure steam has larger bubbles, leading to:
- Carryover of water into the steam system, reducing steam energy and efficiency.
- Wetter steam, increasing maintenance costs from erosion and corrosion.
- Foaming, caused by turbulence at the water surface, especially with poor water chemistry.
5. Steam Trap Inefficiencies
Steam traps are designed for a specific condensate load and pressure drop. A reduction in boiler pressure can lead to:
- Undersized traps: Unable to manage increased condensate loads, causing inefficiencies.
- The need for re-trapping the system, adding time and costs.
A Better Approach: Optimise, Don’t Compromise
If your goal is to reduce fuel consumption and CO₂ emissions, reducing boiler pressure isn’t your only—or best—option. Greater savings, with far less disruption, can often be found elsewhere in the steam and condensate loop.
Here’s how Spirax Sarco’s Advance Consulting service can help:
1. Optimise Your System
- Conduct detailed energy audits and surveys to identify inefficiencies.
- Use digital tools to track energy usage and pinpoint areas for improvement.
2. Improve Maintenance and Monitoring
- Implement smart monitoring systems to proactively manage performance.
- Regularly inspect steam traps, control valves, and pipework to maintain efficiency.
3. Upgrade Technology
- Invest in technologies like heat recovery systems, which can deliver substantial savings without compromising system performance.
- Consider TargetZero solutions to minimise or eliminate carbon emissions from steam generation, whilst maintaining output.
The Spirax Sarco Philosophy: Keep It Designed for Purpose
Boiler pressure should generally remain at its original design conditions. Changes can disrupt your system, creating more problems than they solve. Instead, focus on holistic system optimisation, targeting areas with greater potential for savings.
By partnering with Spirax Sarco and leveraging their Advance Consulting expertise, you can achieve meaningful reductions in fuel consumption and emissions—without risking the integrity of your system.
