Hard water
Q:
Why hard water causes problems?
A: Hard water is a perfectly natural phenomenon. It contains a high percentage
of minerals which are present as salts in solution. They are mainly calcium
and magnesium based, and they are essential to plant and animal life.
Unfortunately, they also cause problems. The main culprit is calcium carbonate, which is the salt responsible for hardness. It is equally responsible for the formation of limescale, because of its rare property of dissolving in cold water and precipitating in hot water. Most other salts dissolve in hot water.
The loss in heating efficiency caused by the build-up of limescale in your water system can be extremely expensive, not only in terms of heating bills, but in appliance repair costs. The extent of the damage which can be caused is not always appreciated, until it is too late.
Q: The problems of hard water?
A: Anyone living in a hard water area knows the problems of limescale. Kettles and shower heads scale up, scum lines appear on baths, shampoos don't lather as they should. These are obvious symptoms, and there are many more, but the biggest single problem lies in the damage limescale does to pipes and the consequent waste of energy it causes, as the graph shown here illustrates.
Q: How does Water-King solve the problems associated with hard water and provide softer water for the whole household?
A: Dr W. G. Abi Aoun B.Sc. MSc. Ph.D., an acknowledged expert in water treatment explains:
Water-King operates by inducing a specially selected range of electro-magnetic signals into the water through aerials wrapped around the pipes. These signals are carefully controlled by pre-programmed micro-chips. The combination of frequencies and amplitudes is unique (patent pending), and these interact with the dissolved salts present in hard water, whether it is flowing or static, causing the formation of sub-microscopic clusters. These clusters act as nucleation seeds for the precipitation of calcium carbonate when the water is heated. Precipitation, in the form of larger crystals, occurs on these seeds in the body of the water and not as a hard deposit of limescale on the inside of the pipes.
Since the presence of nucleation seeds encourages the precipitation of calcium carbonate in the form of crystals in suspension, limescale encrustation in hot water cylinders, on heating elements and other surfaces in contact with the water is substantially reduced. The crystals will either settle as a soft sludgy deposit, or be carried away with the flowing water. New appliances such as showers, hot water cylinders and combi boilers will remain clear. If the appliance is already encrusted, existing deposits will become soft and will either break off or be washed away in the flowing water.
To users, the treated water which contains less dissolved free calcium appears to behave much like chemically softened water. There is reduced encrustation, better lathering and less scum formation in the hot water. At the same time, but unlike chemically softened water where all the minerals are removed, the cold water from the tap can be safely used for drinking. There is no need for a separate “hard water tap” and no health risks whatsoever.
The Water-King
is the only electronic water treatment device that has been tested by
independent accredited laboratories and proven to produce softer water.
It has revolutionised the way experts think about providing solutions
to hard water problems.
Technologies
Q. Getting physical - the intricacies of electronic water conditioners
A: JONNY SECCOMBE CONSIDERS THE DIFFERENCES BETWEEN ELECTRONIC AND MAGNETIC FORMS OF WATER TREATMENT FOR PREVENTING THE BUILD-UP OF SCALE IN HEATING AND HOT-WATER SYSTEMS.
Externally fitted electronic water conditioners work on an entirely different principle to the well known intrusive 'in-line' magnetic system, but the two are often confused or grouped together as 'magnetic'. Intrusive magnetic systems have been around for many years, much longer than electronic systems, but the fundamental mechanisms by which the magnets work are only now being understood.
Current thinking suggests that magnetic systems rely on the release of corrosion byproducts which act either as scale inhibitors or as nucleation seeds to stimulate the formation of nonencrusting scale. The corrosion is caused by the direct electric current which is created by water flowing past the magnet. The system will only work when water is flowing, and its effectiveness is governed very much by the rate of flow of the water and thus the size of the direct current. When the flow rate is low or intermittent, the effectiveness of the system is much diminished.
The fundamental problem with these systems is that once the source of the corrosion by products is exhausted, the process stops. Even before the source is exhausted, the effect can be greatly diminished because the source can become encrusted with other compounds already in the water, thus in hibiting the corrosion itself and ultimatley resulting in 'passivity'.
It is generally accepted that when the in-line magnetic systems work at all, they gernerally have a limited, sometimes quite short, lifespan, after which they becombe ineffective. They then need to be replaced entirely.
DIFFERENT PRINCIPLE
The more modern electronic systems work on an entirely different principle. They creat a series of alternatingcurrents in the water which interact with existing compounds already in the water to generate nucleation seeds.
These seeds then go on to inhibit scale encrustation by stimulating scale formation in particulate form within the body of the water.
There are many different systems on the market which have a varying degree of effectiveness. Three key points govern their effectiveness.
The complexity
of the signal pattern and the cosistency by which it is generated.
The overall output power of the signal.
The means by which the signal is transmitted into the water.
The most effective systems generate a complex wave pattern generated by
a programmed microchip.
Our own program for the Water-King has been developed over the last six years as a result of intensive research with our end users. As most of our early customers were derived from our mail order business, we have been able to continue contact with them to establish the effectiveness of different products. Over the years we have continually refined the product fromexperience learned in the field and we continue this product improvement as we discover more about the processes involved.
Most systems currently on the market generate an output of around 5 to 9 V. TheWater--King system generates a fluctuating signal with a peak output in excess of 80 V. Unlike magnetic systems, the current from electronic systems is alternating and therefore does not cause corrosion or any of the by product associated with it, As the current is not dependent on the flow of water, static water can be treated equally as well as flowing water. This is a considerable advantage because water does not need to even pass by the unit to receive effective treatment.
The signal from electronic devices is transmitted into the water by one of three means. Most common is the closed-loop system where a wirw comes out of the control box, around the pipe a few times and then goes back into the box. Some units employ a ferrite ring to transmit a powerful magnetic field and others, use open-ended aerials wrapped around the pipe. The attraction of the latter system is that one or more of the aerials can be attached to the pipe itself or to the water heater or place where scale is being generated - making the signal transmission very much more effective.
Some manufacturers claim that their systems are uniquely capable of transmitting the signal both upstream and downstream in the water. Obviously this is an erroneous claim as electricity cannot be forced to travel in one direction in a conducting medium such as water. The signal does decay with distance from the point of generation, and the closer the device is located to the point that scale forms, the more effective it will be. We know that our own product is more effective where there is conductivity. Plastic break tanks cause a loss in this continuity, but the problem can be overcome by cross bonding of the pipework or grounding one of the aerials of the unit across this break point.
EFFECTIVENESS
Correct siting of the signal unit is also an important factor in improving its effectiveness. Pumps will intefere with signal transmission. If water treated immediately prior to the pump, scale may be encouraged to form very rapidly within any low-pressure area within the pump, causing it to seize up. We recommend that the signal generator should be fitted on the discharge side of the pumps.
Magnetic-based systems have had a long occasionally successful history of water treatment. It is clear that the modern electronic-based systems are far more effective in a wider range of applications for a muchlonger period of time, and in due course they will become the main form of non-chemical water treatment.
Jonny Seccombe is managing director of Lifescience Products
Q. Descaling without acids
A: Preventing scale formation in water systems and removing existing scale deposits can have a common solution, as Jonny Seccombe explains.
The capabilities and shortcomings of many of the currently available physical water conditioners are now commonly appreciated, but less well known and often surprising to many engineers is the capability of some of these products to reduce, and sometimes totally clear, existing scale from plant and equipment that has been exposed to hard water over a period of time.
Traditional methods of treating scale-encrusted appliances range from scrapping and total replacement to time-consuming chemical descaling using acid in some form or other. Apart from the downtime and health hazards involved with using acids in water-handling plant, an undesirable side effect of acid washing is the unavoidable etching of the metal where scale has formed. The irony is that scale is attracted to rough surfaces, and that is exactly what the acid wash creates once the scale is dissolved. When the plant is returned to normal usage, scaling can be expected to occur much more rapidly than before.
As an alternative to traditional descaling methods, it is now becoming more widely appreciated that some of the electronic water-conditioning systems are capable of rapid and effective descaling without any further intervention. Although there are a number of well documented field studies that provide sufficient evidence of the effectiveness of these water-conditioning products, the exact mechanisms by which this is achieved are not fully understood.
Electronic water conditioning can cause encrusted scale to break away in large lumps, for easy removal by manual cleaning.
Erode
One hypothesis is based on the premise that scale is seldom in a stable form. Changes in pressure, temperature and water quality are continuously causing elements of the encrusted scale to dissolve back into the water, but normally fresh scale will deposit to take its place. However, where the water is treated with a suitable device, the fresh scale forms in the body of the water as suspended particles and not as an encrustation on the surfaces. Gradually, the old scale will erode from the surface in contact with the water.
Normally this process would take a very long time to remove all the limescale, but what is unusual about electronic water conditioning is the way that the scale breaks away quite rapidly. After only a few weeks, it is common to find that all the scale has broken away as plates, leaving the underlying surface almost entirely scale free. It seems that the dissolving scale weakens the whole matrix of the scale deposit to such an extent that it breaks away from the back surface in a plate form.
An example of what can be achieved is evidenced by some work carried out on the P&O cross-Channel ferry Canterbury, where Water-King units were installed to provide partial softening. The domestic-hot-water services were being provided by a 1500 litre calorifier, which, in spite of annual dry docking when some acid washing was carried out, over a period of years had accumulated about 7 mm of encrusted scale on the internal surfaces of the tank. Within three months of installation of a Water-King WK3 on the 54 mm cold feed to the calorifier, most of the encrusted scale had broken away and fallen into the bottom of the calorifier. Lumps of scale 7 mm thick and 4 cm square lay in the bottom of the tank, from where it was easily removed by manual cleaning. The downtime for scale removal was around six hours.
Following three months of electronic water conditioning of the domestic-hot-water services , the downtime to remove scale from this 1500 litre calorifier was around six hours.
Independent research
The speed with which the process can occur is also well documented by independent research carried out by TFW Associates on a house in Portsmouth. The level of residual calcium bicarbonate in the hot water of a domestic heating system was measured weekly after the installation of Water-King. The base value of the cold-water inlet was 150 ppm, which dropped to 100 ppm with normal heating and no water treatment.
After installation of the electronic water softener, the level rose progressively to peak at 152 ppm after four weeks before declining rapidly to less than 50 ppm for the last seven weeks of the trial. These results indicate that the descaling process took place within the first five weeks after installation of the device.
Whilst the scale that breaks away from inside a calorifier causes few problems as it settles in the bottom of the tank, scale breakdown within hot-water-service pipes has the potential to cause blockages, especially in shower heads and thermostatic mixing valves. The benefit of being able to effectively descale a complete hot-water system without any downtime must be tempered with the caution that vigilance against full and partial blockages is essential. Strainers and filters need to be reviewed, and loose scale removed if flow rates deteriorate. Certain types of heat exchanger, such as those with a heat store and small-bore domestic feed, can become completely blocked as the scale breaks away within the small bore supply. For these we recommend a chemical descale before an electronic water conditioner is fitted.
In spite of these drawbacks, the benefits of non-chemical descaling are very considerable, and a plant that would otherwise be considered only for scrap, can be rescued and have its effective life prolonged. Having completed its initial descaling task, electronic water conditioners can go on to provide continuing scale protection and, even, partial water softening as well. All these benefits are realised at a cost considerably less than traditional water softening.
Jonny Seccombe is managing director of Lifescience Products Ltd, 185 Milton Park, Abingdon, Oxon OX14 4SR.
Ozone
PDF-Use
of Ozone to Improve the Safety of fresh Fruits and Vegetables
Q. OZONIZATION OF COOLING TOWER
OZONIZATION OF COOLING TOWER
INTRODUCTION
Water cooled
chillers use evaporative cooling towers as the ultimate source of heat
rejection. As spray water of the tower re-circulates through condensers
of the HVAC machines, it is essential that the following are achieved;
a. Water in the system does not cause corrosion of the condenser tubes
and pipes.
b. As this water sprays through the tower, air flow causes drift, carrying
water droplets to a large area in the vicinity of the tower. Hence, it
is absolutely essential to ensure the level of water borne bacteria and
viruses in the water is below accepted norms (1000 CFU/ML Colony Forming
Units per milli Litre). It is now a well known fact many diseases, including
the dreaded Legionnaire's disease, are caused by the fine mist from cooling
towers. Importance of this is more pertinent applications, close to high
populated areas.
c. Minimize build up of water borne microbes such as algae, plankton etc.
d. Keep water clean from dirt, sediments and particulates.
e. Minimize build up of scales in the condenser tubes. Increased scaling
results in increased power consumption of HVAC compressors, a major factor
in operating cost of the system.
f. To comply with laws restricting discharge of chemically treated water.
CONVENTIONAL
TREATMENT (MULTI CHEMICAL TREATMENT)
To achieve these, it was customary to use a variety of multi chemical
treatments, combined with filtration. Usually, more than one chemical
is used, as no one chemical can provide solution to all above problems.
The applied chemicals are spent in the water, and therefore, it is necessary
to add chemicals continually. As part of the water in the system constantly
evaporates, concentration of residual chemicals builds up in water in
the sump of the cooling tower. It also increases calcium and magnesium
count in tower water, major components contributing to scale formation
in condenser tubes. Additionally, it alters PH of water and disables its
corrosion inhibition ability. To restore this, it becomes necessary to
drain out a large portion of water from the sump of the tower. This is
called sump blow down or bleed off water. Blow down water (together with
water lost due to evaporation and drift) are made up by continuous injection
of fresh water into the sump, called make up water. If adequate quantity
of water is not blown down, the result is increased scale formation on
condenser tubes, and increased power consumption. The trade off is in
favor of blowing down the necessary quantity of water and keep scale formation
down.
Blowing down water causes serious concerns due to the high cost of operation of the plant, and environmental problems. Typically, a chemically treated cooling tower operates at cycles of concentration between 1.5 and 5.0. Cycles of Concentration is defined as the number of times a molecule of water is rotated in the condenser system, before it is blown down, or carried away as drift, or boiled through process of evaporation. Analytically, it is the ratio of the sum of water evaporated, water lost due to drift, and water blown down to the sum of water blown down and drift loss. C = {E/(B+D)}+1. E and D are constant and B is the only variable component. Higher the value of C, lower is the volume of water blown down. Drift is also a form of blow down, except it is uncontrolled.
OZONE TREATMENT OF COOLING TOWER WATER
Present trend in the industry is to use the alternate method of treating
cooling tower with ozone. This achieves all of the purposes served by
multi chemical treatment, and more. Briefly described, it involves production
of low concentration of ozone at site, and injecting this into a side
stream water taken from the tower basin, and returning the injected water
(with ozone) to the basin. Ozonization of tower water:
· Disables scale formation tendency on condenser tubes.
· Suppresses corrosion of condenser tubes and condenser water pipes.
· Eliminates water borne bacteria, viruses, algae, plankton and
microbes in the water.
· Removes odors and color from condenser water system
· Eliminates use of chemicals completely.
· Can discharge directly to sewer.
· Bleed off water can be used for irrigation by maintaining the
total dissolved solid content within 3000ppm.
Cost of operating the plant is very low, because ozone is produced in situ. The best known advantages of this are:
Reduces dramatically blow down or bleed water, and reduces power consumption. Operating the tower at cycles of concentration of 20 is quite easily attainable. This results in incredible reduction in electricity and water consumption or make up water. During mild seasons, it may well be possible to operate with zero blow down. Annualized savings in blow down water is around 80%, a phenomenal reduction. Savings in electricity of 15% is attainable.
Reduces electrical power consumption of HVAC compressor. For a retrofit conversion form chemical to ozone system, we would expect power savings of over 15%.
ADVANTAGES
OF TREATMENT WITH OZONE
Advantages of ozone system over chemical system are many: Direct and tangible
economic advantages resulting in direct cost savings, consequential and
indirect advantages, and environmental benefits. Following is brief summary
of these;
DIRECT AND
TANGIBLE ECONOMIC ADVANTAGES
a. Savings in cost of water: Blow down water is reduced dramatically,
by over 80%.
b. Savings in power consumption of HVAC compressor. For retrofit, we would
expect power savings in excess of 15%.
c. Addition of chemicals incurs recurring cost. In ozonized towers, chemicals
are totally eliminated.
d. Although chemical treatment inhibits corrosion, yet corrosion formation
is quite high. In chemically treated systems, corrosion of 3 MPY or more
for copper is not uncommon. Ozonization reduces corrosion significantly.
Typically, in ozonized systems, corrosion of 0.3MPY for copper is attainable.
This is a very impressive figure by industry standards.
e. Scale formation on condenser tubes with chemical treatment is high.
Periodic descaling of condenser tubes is necessary, typically once a year.
This results in increased power consumption, and adds to cost of maintenance
of the plant. In ozonized system, the need to descale condenser is vastly
reduced. If operated properly, it can be eliminated altogether. Descaling
once in 5 years is a reasonable assessment.
f. Discharge of chemical laden water is not permitted by law in most countries.
It should be treated prior to discharge. Cost of this treatment is very
high. This may not yet be legislated in many countries, but it is likely
such legislation will come in effect soon, as environment consciousness
is on the rise globally. Blow down from ozonized cooling tower does not
require any form of treatment because it is totally free from all chemicals.
CONSEQUENTIAL
AND INDIRECT ADVANTAGES
a. Increased Plant Capacity: Due to scale formation in the condenser tubes
(with chemically treated towers), discharge pressure of the HVAC compressors
always tend to remain high. In an ozonated system, due to elimination
or vast reduction of scales on condenser tubes, compressor discharge pressure
is lower. This results in savings of electrical energy of the compressors.
Besides the power consumption factor, operation of compressor at reduced
discharge pressure increases cooling capacity of the installed HVAC system,
thus reducing the capital cost of the system, or allowing plant augmentation
without additional capital. Operation of compressor at reduced discharge
pressure extends life of the compressor, as there is less thermal stress
on the system. This prolongs utilization of the invested capital.
Reduction
of compressor discharge pressure by 5% results in reduction of power consumption
by approximately 7%, and increase of system output capacity by about 3%.
b. Descaling condenser tubes, typically once a year for chemically treated
systems, results in plant down time. Each condenser takes at least 3 days
to descale. This is either eliminated or reduced vastly in ozonized system,
resulting in better plant and capital utilization.
c. Frequent descaling reduces life of the condensers, as each descaling
results in scrapping metal out of the tubes. Reduction or elimination
of descaling results in longer plant life, and better capital depreciation.
d. Continuous addition of chemicals requires holding of inventory, warehouse
space, time of warehouse staff, and upkeep of protocols needed to handle
corrosive chemicals. Ozone treatment eliminates all these.
e. Elimination of bacteria and viruses results in reduced sickness and
allergies. This is particularly significant if HVAC fresh air intakes
are placed in leeward direction of the tower. Contaminants from cooling
tower drift have been recorded several miles away from cooling towers.
This is a very important consideration for a public building application.
f. Condenser tubes and condenser water pipes will always remain clean
in an ozonated system. This results in cleaner appearance, hygienic system,
reduced maintenance and longer life of the HVAC system. Water in cooling
tower basin will be clean and clear, unlike the brown, dirty, mucky water,
typically seen in basins of cooling tower working on chemical treatment.
ENVIRONMENTAL
BENEFITS
a. Incredible reduction of water consumption results in water conservation
and preserving underground aquifers, our obligation to future generations.
b. Significant reduction in electrical energy results in reduced use of
fossilized fuel, reduction in greenhouse effect, acid rain and global
warming.
c. Draining chemically laden water into municipal drains eventually results
in contamination of under ground aquifers. Preservation of national aquifers
is of paramount importance for future generations of a countries population.
Blow down water from ozonized cooling towers does not impose these problems.
d. Elimination of bacteria and viruses results in better air quality for
the surrounding areas.
Given the prevailing cost of water and electricity, in many countries,
we reckon payback period for ozonization of the tower is 2 to 3 years.
There after, it is just a profit situation.
FEASIBILITY STUDY
Detailed Feasibility Study and Return and Investment Analysis can be custom provided to suit clients specific requirements, several site specific information is needed to provide the study.
Q. Drinking Water Quality Limits
Drinking
Water Quality Limits:
Health Canada and the Environmental Protection
Agency (U.S.A)
pH 6.5-8.5
Iron 0.3 mg/L
Total Dissolved
Solids (TDS) 500 mg/L
Conductivity 2000 microhomes
Calcium 200 mg/L
Magnesium 200 mg/L
Hardness 500 mg/L
Sodium:
normal limits 200 mg/L
reduced limits 20 mg/L
Potassium 100 mg/L
Nitrate 10 mg/L
Nitrite 10 mg/L
Flouride 1 mg/L
Chloride 250 mg/L
Silica 25 mg/L
Alkalinity 500 mg/L
Mangenese 0.05 mg/L
H2S 0.05 mg/L
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