Saturated steam is steam that occurs in a state of equilibrium between the liquid and gaseous phases, i.e. where the rate of vaporization is equal to the rate of condensation; this is in contrast to super-heated steam, which is heated to higher temperatures.
The level of water present in the steam is indicated by a number between 0 and 1, which is known as the steam quality. Saturated steam is classified as follows, depending on the steam quality value:
- Dry Saturated Steam: Steam quality = 1 (indicating the complete absence of liquid water);
- Saturated Wet Steam: the Steam quality value less than 1.
Using dry steam reduces water consumption, and hence the quantity of water wasted during the steam cleaning process.
The temperature of the steam at the outlet of the REA STEAM CLEANING saturated steam generator boilers is 188 °C (corresponding to a pressure of 12 bar), and never falls below 150 °C during the contact phase with the surface to be cleaned.
REA STEAM CLEANING saturated stream generators produce a steam quality rating of greater than 0.9, containing less than 6% water (dry saturated steam).
The action of saturated steam, as applied in the field of cleaning, degreasing, and disinfection, is the result of 4 factors:
- the effect of heat on the dirt and the surfaces
- solvent effect: free water + condensate
- effect of mechanical energy: via micro-cavitation
- effect of the mechanical energy of the steam jet (flow x pressure).
COMPARISON BETWEEN TRADITIONAL METHOD AND STEAM METHOD
TRADITIONAL METHOD : 5 stages
- Physical removal of larger debris, sometimes followed by a pre-washing phase that makes it easier to detach the dirt.
- Cleaning, often with chemical agents.
- Final rinsing and drying
STEAM METHOD : 3 Stages
- Physical removal of larger debris.
- Cleaning and disinfection in a single operation, often without chemicals.
- Drying, if necessary (Using Hot Steam Favors Evaporation Of Water)
ADVANTAGES OF SATURATED STEAM
1. ELECTRICITY AND WATER CONSUMPTION:
one of the most widespread concerns regards the electricity consumption of a steam generator.
The first thing to point out is that thanks to the patented boiler, REA generators guarantee very high yields (15 Kg/hours of steam at a pressure of 12 bar with a 9 kW heating element).
Under normal working conditions the elements are energized for about 70-80% of the time, however, it is important to consider that an operator will be delivering steam for around 50/60% of the time during any given continuous period. Thus, it is possible to carry out the following calculation (assuming a basic 9 kW machine) Kw 9 x 80% heating element energization time x 60% maximum delivery period = 4.32 kW (actual consumption).
The same principle may also be applied when calculating water consumption, hence, the quantity of wastewater produced.
Again, assuming a 9 kw generator, we can calculate the water consumption related to the production of steam as follows: 15 Lt/h x 60% of the maximum delivery period = 9 lt/h (actual consumption), whereas in the case of waste water (while this figure is related to the quantity of steam produced too, it is also necessary to factor in the amount of detergent, which is between 2 and 4 lt/h, depending on the application), it is necessary to take evapouration into account, hence the figure is reduced by a further 50% (at temperatures of at least 20 °C), meaning that the quantity of waste water attributable to steam is equivalent to around 5 Lt/h.
2. RAPID INTERVENTION:
washing with saturated steam offers significant time savings over traditional cleaning methods while maintaining the operability of installations.
Traditional systems, such as cloth and detergent or low-performance steam generators are time consuming and may expose the operator to risks when attempting to reach some parts of the machinery, whereas pressure washer systems, while faster, are less accurate than saturated steam generators, and introduce a series of complications and risks (large quantities of free water, sensitive parts exposed to high pressures, not possible to use hot water without a release vent, operator fatigue and necessity for protective clothing, etc.)
It is important to bear in mind that machine tools are never designed to be cleaned using water, much less pressurized water.
3. WASTE PRODUCTS:
an average generator with a power rating of 18 kWh, capable of producing 30 kg of steam at a pressure of 12 bar, offers a rapid response and very low production of wastewater.
Since the operator would be delivering steam for approximately 50/60% of the time under continuous working conditions, a high proportion of the steam does not condense, and, wherever possible, a mixture of water and detergent is used together with the steam in order to accelerate the process when cleaning machine tools, we can estimate that the cleaning process would generate, on average, 10-15 litres of wastewater per hour.
These data are very different from the typical values of a medium sized pressure washer, which would generate in the order of 400/600 liters of wastewater (or even more) under the same conditions, resulting in significantly greater water consumption and disposal costs, and increasing the risk of damage to the systems to be cleaned.
in the majority of cases, the degreasing, sanitizing or cleaning process is guaranteed without the use of chemical detergents. If needed, our machines are designed to regulate the use of such detergents to a minimum. This feature means that saturated steam is ideal for use in the agro-industrial sector, where the use of chemical agents is strictly limited by the applicable regulations.
5 RISK OF INJURY:
REA saturated steam generators are manufactured to the strictest safety standards and are designed so that personnel is exposed to the minimum of operating risks.
Steam scalding risks are limited to a small number of easily identifiable hot parts of the equipment, at a distance of 15/20 cm from the outlet the steam is no longer a source of danger, and when working at low pressures there is no danger of ejected debris striking fellow workers or other equipment.
Personnel must observe the appropriate safety regulations when using the machines and use the prescribed personal protective equipment (gloves, goggles, protective clothing, and earplugs).