 Instant steam puts heat on MRSA
Portable, superheated, high pressure steam is now available, writes Nina Morgan in Chemistry & Industry |
 Portable, superheated, high pressure steam that could be used in applications as diverse as hospital disinfection or removing chewing gum from pavements is now available thanks to the development of a catalyst by UK-based company, Oxford Catalysts.
A small bed of powdered precious metal-based catalyst, the size of a sugar cube, is incorporated into a specially adapted nozzle mechanism on a standard plastic spray bottle containing a mixture of methanol and hydrogen peroxide. Squeezing the trigger causes the liquid fuel to pass over the catalyst and initiates the spontaneous and highly exothermic reaction.
The reaction occurs very quickly – it takes just 1-2s to produce steam -- and it takes place at room temperature and atmospheric pressure. It releases only C02 and high temperature steam. A reactor the size of a sugar cube can pump steam at a rate of 7 L/minute at up to 800°C. A reactor just 2cm high – roughly the height
of a stack of six £1 coins – is capable of producing 70L of 650°C
steam/minute.
‘Instant steam’ is not designed to generate the vast quantities used in industry -- BASF, for example, used 53.8m t of steam in its operations worldwide in 2006. This is produced using waste heat or by cogeneration, operates at higher temperatures and pressures and requires a substantial capital investment. ‘Instead, the value of instant steam lies in creating truly portable steam that can be generated intermittently on demand,’ explains Dave Wardle, business development director at Oxford Catalysts.
One important application could be to improve steam-based hospital disinfection systems, already widely applied in Denmark both for hospital cleaning and combating sick building syndrome. Research commissioned by OspreyDeepclean, a subsidiary of the Liverpool UK-based company Proventec, and carried out by the Hospital Infection Protection Environmental Research (HIPER) Unit at University College London Hospital in 2006, demonstrated that dry steam applied at temperatures ranging from 150-180°C could destroy bacteria, including antibiotic-resistant ‘superbugs’, such as MRSA and Clostridium difficile, in less than 2s without the use of chemicals. OspreyDeepclean and HIPER plan to publish the results of this research soon. The company is also involved in establishing a new standard for steam disinfection.
However, the first potential use for the instant steam technology envisaged is in GumBuster, Proventec’s steam-based technology for removing chewing gum from indoor and outdoor surfaces. GumBuster presently requires a minimum of 3kW of electrical power to generate the steam used by each operator and relies on generators carried on trolleys or in vans. Instant steam technology could make it possible to develop a backpack-
based system to make GumBuster even more convenient and
cost effective.
‘Steam - in combination with a specially developed range of tools and accessories to apply the steam to surfaces and used in accordance with standard operating procedures – is an important part of our integrated approach to infection control,’ explains Thomas Stuecken, managing director of OspreyDeepclean and chief commercial officer at Proventec. ‘The steam has to be extremely dry and at a high temperature. This is where Oxford Catlayst’s technology scores over conventional technologies. Its use will make the system more portable and make it possible to place the steam where we need it, when we need it. If we get the healthcare sector right, and if and when Oxford Catalysts develops its technology to meet our requirements, the opportunities are enormous,’ he says.
Wardle is similarly optimistic – and not just on the cleaning front. ‘This technology opens the door to new opportunities where the traditional method of making steam was considered inadequate or impractical,’ he says. ‘The design is very versatile and can be implemented to fit both small and large scale applications. We’re always on the lookout for new ideas for uses.’
- Portable cleaning power
On the household front, instant steam created using a trigger bottle could form the basis of a new category of retail products where the heat from the steam is used to increase the efficacy of cleaning solutions or detergents used for degreasing. The steam alone could be used to kill weeds, or strip paint or difficult wallpapers. Instant steam could also pave the way for the development of cheap and efficient sterilising systems, or form the basis for down hole steam generators to create localised heat for enhanced oil recovery. It might also be used to drive small turbines to generate electricity in backup power systems. Or more speculatively, the steam could be used in turbine-powered environmentally friendly cars designed for urban use. With a slightly different fuel formulation combined with a more energetic catalyst, instant steam could even be used as a rocket propellant.
| Steam generation methods compared |
| |
Traditional Steam |
Oxford Catalyst Instant Steam |
| |
|
|
| Start up |
Slow start up |
Instantaneous start up |
| Energy |
Energy required to vaporise water |
Self starting reaction |
| Temperature and pressure |
High temperatures are only achievable
by higher pressures, and thus, expensive vessels and associated systems |
Decouples the dependency of steam temperature on pressure |
| Mobility and portability |
Usually requires an external power source thus limiting its mobility and power |
Requires only a rechargeable battery for temperature/flow control |
| Gas composition |
CO, CO2, NOx and other gases emitted
during fired boiled heating or at site
of electrical energy production |
Approximately 15% (w/w) C02 produced,
depending on fuel concentration |
| Size |
Requires tank, boiler and superheater |
Only requires a fuel reservoir and a miniature reactor |
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