Water – Use, Abuse and Conservation
Water quite literally flows through every facet of life, being the key element for everyone and everything on the Earth.
The world’s population is increasing at 1.1 per cent (roughly 83 million) every year, an incredible and alarming rate straining the world’s fresh water supply.
The increasing pressures between what humanity demands and what is currently available emphasises the importance of conservation.
With increased competition for domestic, industrial, and commercial uses, efficiency is required across markets.
We must boldly declare the deployment of new strategies, in this case addressing inefficiencies in cooling tower operation. (From Global Water Intelligence)
What is wrong with using cooling tower?
It is obvious that this is an archaic, wasteful technology from the days of plenty. It is not sustainable today, so there is a need to think out-of-the-box!
The question is, “If the condenser is eventually cooled by water evaporation, why not use direct evaporation in the condenser itself and eliminate the entire condenser water system, including the cooling tower?”
Hah! Easier said than done?
It is actually easier once you realise that it is not necessary to heat water to 100C for converting it into vapour.
Have you ever noticed what happens when you cover a cup of steaming hot tea or coffee to keep it from cooling down? When you lift the lid, there is water on its underside. Vapour is produced when the vapour pressure within the liquid is high enough for it to break through the surface tension barrier of the liquid.
If you are heating some water in a pot, then it must first absorb enough energy to build that internal pressure. The larger the pot, the longer it will take to reach that level. Conversely, the smaller the volume, the faster the heating.
That is our key! If we atomise the water, the mass of each micro particle will be very low. Thus, when that particle just touches a hot surface, it will vaporise in an instant. So, if we pump the atomised fog into the tubes of the condenser instead of liquid water, vapor should come out at the other end.
The next section shows a diagram and description of a system designed on that idea.
Its condenser generates the water vapour, which is condensed by the other components. There is no loss of water; the air is recycled in a closed loop.
What are the benefits?
To the User
• Savings in capital cost due to
elimination of the cooling tower,
condenser water pump and piping,
water softening plant and peripherals.
• Further, saving in capital cost due to
reduced land requirement
• Saving in operation and maintenance
costs due to the above
• A major saving in the cost of water,
since almost all of it is recovered.
To the Society
• Availability of 4.6 billion cubic metres
of more water per year, that is the total
water consumption of coal power
plants in India.
• This can meet the basic water needs
of about 25 crore people.
• When just the India figures show such
huge numbers, one can imagine the
global savings of water by elimination
of the cooling towers.
To the Environment
In order to feed these towers, fresh water is being diverted from rivers, lakes, dams and aquifers. Now it will be released for human use, thus reducing the potable water scarcity.
Surendra H Shah
BE Mechanical Engg, Clemson University,
USA Founder & Owner of Panasia Engineers
Pvt Ltd, Mumbai