Steam is an inherently natural medium and is something familiar that we can all understand on its simplest level – it is just the boiling of water, but with some totally unique properties. This is why it has been adopted as the preferred method of delivering thermal energy and motive energy throughout our industrial history. Distributing steam around a system, a building or a process can be done safe in the knowledge that is just water, but with far higher thermal qualities. As technology advances, the methods of steam generation will continue to become:
• Increasingly sustainable
• Capitalising on renewable sources
• Optimised through digital advances
Our ability to produce it, harness it and control it makes it an incredible medium with a vast range of applications and uses including electrical power generation, sterilisation, cooking and cleaning. As renewable generation solutions and digital controls evolve, steam will be a vital part of our sustainable future as we transition to greener technology. As sustainability agendas accelerate and organisations look to invest correctly in green technology, the availability of renewable power is on the rise, which fits well with advances in the electrification of steam. So why is steam the ideal choice for thermal energy transfer?
1. High energy density
Steam has a high energy density enabling effective transfer of large quantities of energy. If we circulate water with a flow and return temperature of 71 – 82oC (160 – 180oF), then each litre (or kg) of water has the ability to deliver 46 kj/kg. If we circulate water with a flow and return temperature of 60 – 80oC (140 – 176oF), then each litre (or kg) of water has the ability to deliver 84 kj/kg. In comparison, if we take steam at 1 bar g, we have the ability to deliver 2201 kj/kg. If the application allowed for subcooling of the condensate to 10oC (a drop of 110.42oC), then the additional energy available is 464 kj/kg. By adding this to the enthalpy of evaporation we can achieve a total of 2665 kj/kg. Per kg, steam Hfg has 26 times more useful energy than water at delta 20oC, or 48 x more than water at delta 11oC.
2. Precise Temperature Control
Steam has a temperature that is relative to the pressure and maintains a constant temperature as it gives up its energy and changes state from a gas back to a liquid (unlike water that starts to lose temperature immediately as it gives up energy). This allows steam to maintain uniform temperature during heat exchange. In comparison, water would see a temperature drop as soon as it starts to exchange energy.
3. Smaller infrastructure
When steam pressure increases, the volume decreases. So if we distribute at a higher pressure, steam pipes are smaller, minimising valuable process space, lowering costs and minimising radiated losses.
4. Flows naturally
Steam moves from areas of high pressure to areas of low pressure without the need for pumps. This eliminates high electrical loads and maintenance associated with circulation pumps. In addition to this, a plant will only consume the steam it requires when needed, when compared to wet systems that continually circulate. If electric condensate return pumps are used, the electrical load is far less than that of a water system, due to steam’s high energy density.
5. Efficient heat transfer
Steam can be used directly onto products e.g. equipment sterilisation in healthcare, cooking produce in food and beverage or even indirectly via heat exchangers. Steam is a fantastic heat transfer medium. When using an indirect heating surface (heat exchangers), the heat transfer coefficient when using steam is much greater than other heating mediums.
6. Natural Water Cycle
Most steam applications use the same cycle as the earth’s natural water cycle (Hydrologic Cycle), so we may see an industrial process, but it is also a very natural process. There are however exceptions such as direct injection.
7. Central to the transition to greener technologies
Thermal heating is commonly reliant on the burning of fossil fuels and industry is increasingly looking at how to generate steam in a carbon-free way. The transition to greener technology can start today through system optimisation, digitalisation, electrification, biofuels and zero emission steam to name just a few. Technology is currently available to reduce carbon emissions, improve sustainability and even fully decarbonise steam production. But there is also huge investment in emerging technologies to help decarbonise steam production in other ways including green hydrogen, advanced electrification and thermal battery technology.
The first step on the road to a green future is to ensure all systems are working correctly and fully optimised – often the quickest wins too. There should be ongoing activities to look at how systems are currently operating and to make sure they are operating effectively and efficiently including:
• Reducing demand through improved plant management and preventative maintenance
• Adopting steam system best practice to minimise plant consumption
• Addressing areas of energy loss by implementing heat recovery
• Maintaining steam quality to maximise process effectiveness
• Measuring of utilities to trend and optimise performance
Even when considering significant plant changes to address sustainability and energy, it is important to understand the starting point for your plant, the base-line energy consumption.
Benefit from the power and capabilities of steam while decarbonising and working towards net zero. Expertise from Spirax Sarco is your gateway to tailored solutions that deliver twenty-first-century steam powered operational efficiency, helping you to meet your sustainability targets and solve multiple business challenges. Spirax Sarco can work with you to give your business a clear forward vision whilst harnessing the power of steam today and in the future.
Make the most of steam in your sustainable future at www.spiraxsarco.com/global/en-GB
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Steam is an incredible heat transfer medium and, it’s come a long way from its traditional associations with locomotives and the Industrial Revolution. Today it’s an integral, clean and essential part of modern technology. Without it, our food, textile, chemical, medical, power, heating and transport industries could not exist or perform as they do.
Operating an energy efficient steam system does not mean compromising on performance. By working together, we can help you to reduce costs and carbon emissions and meet sustainability targets.