When we think of steam or steam engines, we tend to imagine historical equipment, and while it’s true that the steam engine played a crucial role in the Industrial revolution, it’s as valid in 2017 as it was in 1880. At Homershams many of our customers are involved in steam generation and boiler maintenance.
What is steam?
Steam is the gaseous phase of water; produced when it boils. Steam itself is invisible. What we commonly call “steam” that we can see, is water vapour caused by condensing steam. Although we may think of steam engines as historic, from Titanic to steam rollers to steam trains, steam is still a very viable and well used means for providing energy to industrial plants today. About 30% of the fossil fuels burnt in the USA are used to produce steam for industry.
Contrary to popular belief, James Watt didn’t invent the steam engine; he perfected the condenser that made the steam engine so much more efficient.
||1769 Stem Wagon
called "Fardier a vapeur"
by Nicolas-Joseph Cugnot
We all know that our cars are powered by ‘Internal Combustion Engines”, but have you thought about what that term means? If there’s “Internal” combustion it implies there must be “external” combustion.
External combustion is the nature of the steam engine, where generation of steam occurs quite apart from the engine in a boiler, and is then fed to the engine whose function is to convert the steam into mechanical energy to drive the wheels. (Compare this to the Internal Combustion Engine where petrol burns WITHIN the engine.
||External Combustion (Steam)
Steam for Industry
In industry steam is the most widely used heat-transport fluid, being a non-toxic substance whose only hazards are in its basic limitations, it’s high vapour pressure and its low critical point. Industry has numerous demands not only for electricity but also heat at various temperature levels.
It’s generated from super-heating water by the burning of fuels. In the South Island, a predominance of coal fired boilers exist, whereas elsewhere in New Zealand, wood, pellets, LPG or other waste products are used.
If the desired temperature lies within the ranges 93 °C and 260 °C, steam is the ideal working fluid. No other material is so adaptable to the dual function of electric power generation and process heating.
Hazards of Steam
The enormous power contained within steam comes in part, from the fact that water expands its volume 1700-times when converted to steam. But this huge expansion can cause explosions. When outsiders visit aluminium smelters, one of the critical safety briefings explains that bottled water must not be brought on site. Why? Because if water were to make its way into the molten metal, this expansion can cause massive explosions. Part of the visitor induction at these smelters is watching a video of an aluminium foundry destroyed by water.
Much of the damage to the Chernobyl nuclear power plant (now contained in its brand-new sarcophagus) was due to liquid water hitting super-heated metal.
Where can we help?
Boiler Safety and Burner Efficiency are of utmost importance. Homershams calibrate/certify pressure gauges used on boilers. Boiler efficiency may be improved (even between boiler surveys) using handheld Flue gas Analysers. They are a product which show a return-on-investment extremely quickly due to reduced fuel costs. We also supply fixed boiler probes such as Zirconia Oxygen Sensors for flue stack gas.