Water treatment Chemicals & its Philosophy

Water treatment Chemicals & its Philosophy

Water is our most important resource, when it is used in heating & cooling systems. There are number of problems that can arise independently the sources of supply ie. Lakes, Rivers, Well or Municipality.

It is difficult to envision the range of problems that the life sustaining substance can cause. Hardness Salts primarily calcium and magnesium carbonates have reverse solubility this means that these salts are at equilibrium at any given temperature but as water is heated, this equilibrium is upset and in order to re-establish equilibrium at the elevated temperature the amount of hardness salts that water can keep in solution must decrease. The result of all this is precipitation of the excess hardness which manifests itself as a scale deposit on heat transfer surfaces. This deposit acts as an insulator and inhibits the efficient transfer of heat. The result is fuel inefficiencies with boiler tube rupture due to overheating and increase maintains cost. Microbiological organisms can infect ion exchange resins, rendering them useless.

Treatment programs whether applied to Steam Generators, Open Recalculating Cooling Systems, Hot Water or Chilled Water Systems are designed to maximize the useful life of welted component at an acceptable cost while minimized negative environmental impact on the receiving streams. Normally treatment is through mechanical means i.e. Filtration, clarification, Ion Exchange, Degasification and Decoration. The effluent from these pre-treatment streams is then chemically treated to render benign those impurities that have escaped the pre treatment phase this is accomplished through the judicious application of chemical formulation The appropriate product in right amount at the proper feed point (optimizing chemical feed). Where replacement of existing treatment program would result in cost saving and for improved protection then such a change is proposed and the recommended program is evaluated for both performance and cost effectiveness. Our approach provides a true service program rather then a sale effort that so disguised as a service program.

It is one of our primary goals to design a water treatment program that is fully compatible with plant operations. A well designed water treatment program complements plant operations rather than call for changes in procedures to accommodate the treatment program.

No water treatment programs will live up to its potential in the absence of proper control.


Why Should Purify Water

Water is nature's most wonderful, most abundant and most useful compound. Presence of impurities in the water, limiting its application and requires treatment before water can be used.

The substance contained in natural or raw water can be listed broadly as follows:-

1) Suspended Impurities are dispersion of solid particles that are large enough to be removed by filtration or settling. The particles which are lighter than water float on the surface.
Suspended impurities include:

(a) Clay silt --- causes turbidity
(b) Bacteria --- some cause disease.
(c) Algae, Protozoa ---- cause order, colour and turbidity.

2) Dissolved inorganic impurities. Some impurities are dissolved in water when it moves over the rocks, soil, etc., these include:

Calcium and Magnesium	Bicarbonate--causes alkalinity and hardness.  Carbonate--            ----  Do    -----  Sulphate--cause hardness  Chloride              ----                 -------  Do    -----
Sodium	Bicarbonate--causes alkalinity and softening.  Carbonate--               -------  Do    -----  Fluride--cause molted enamel of teeth  Chloride--cause taste
Metals and Oxide	Mangages--produces blak or brown colour Iron Oxide--cause taste, hardness, corrosiveness and red colour. Lead--causes arsenic poisoning
Gases	Hydrogen sulphide--causes foul rolten egg smell, acidity and corrosion of metals

3) Organic Impurities include :

Suspended	Vegetable---imparts colour taste and acidity.  Animal (dead) ---- produces harmful disease germs.
Dissolved	Vegetable ---- produces bacterias  Animal ---- causes pollution of water and produces disease germs.

1) pH
2) Conductivity
3) Total Dissolved Solids
4) Alkalinity
5) Total Hardness
6) Chlorides
7) Iron
8) Silica
9) Sulphite

pH:-
pH is a measure of the concentration of hydrogen ion. It is defined as follows:

pH = -log(H+)

where (H+) is the activity of the hydrogen ion (activity in most cases is equivalent to concentration

A neutral solution is defined to have a pH of 7 and as the solution becomes more acidic (an excess of H+ ion) the pH drops below 7. As the solution becomes more basic (an excess of OH- ion) the pH increases. The pH scale varies between pH = 1 where the H+ concentration is 1 Molar (very acidic) to pH = 14 where the OH- concentration is 1 Molar (very basic).


Alkalinity:-
Alkalinity in water is due to presence of bicarbonates, carbonates and hydroxide ions. In raw water alkalinity is mainly due to bicarbonates; however, sometime carbonates may also be present. Out of three ions only two ions can exist in any systems. That is OH, CO3, or HCO3 can either exist alone or in combination with one more ions.

P Alkalinity:-Alkalinity to phenolphthalein represents alkalinity due to OH ions plus ½ CO3 (pH 8.3)

Total Alkalinity :- Alkalinity to methyl orange represents alkalinity due to OH ion plus CO3 ion plus HCO3

 ions (pH 4.3)

Relation between HO, CO3, HCO3 and total Alkalinity

I /	Hydroxide is	Carbonates is	Bicarbonate is	Total  Alkalinity is
P  =  Nil	Nil	Nil	M	M
2P < M	Nil	2P	M – 2P	M
2P = M	Nil	2P	Nil	M
2P > M	2P – M	2(M – P)	Nil	M
P  >  M	M	Nil	Nil	M

Total Hardness

Total Hardness of water represents the sum of the concentration of all metallic cations, other than the cations of the alkali metals and is expressed as equivalent CaCO3 concentration in ppm. In most waters, nearly all hardness is due to Ca and Mg ions; but in some waters measurable concentration of Fe, Al, Mn, Zn and others may be present.

Calcium
In vast majority of raw water calcium is the main source of hardness. In boiler and cooling water systems calcium salts are the main cause of scale.
Although calcium is primarily known for its scale forming tendencies, it also acts as cathodic corrosion inhibitor. All factors being equal, water containing calcium salt will not be as corrosive as soft water.

Magnesium
Magnesium usually forms hydroxides or silicates in boiler water, which are desirable types of sludge. If boiler water alkalinity is low, undesirable magnesium phosphate often forms which
is sticky and scale forming. In cooling water system, magnesium only precipitates when pH is over 10.0.

Relation between Total Hardness (TH) and Total Alkalinity (M)

If	Non Alkaline Hardness is	Alkaline Hardness is	Total Sodium Alkalinity is
TH > M	TH - M	M	Nil
TH = M	Nil	TH	Nil
TH < M	Nil	TH	M – TH

Chloride
All chloride salts are highly soluble in water, so scale is not a problem when chloride salts are concerned, but they are very corrosive in oxidizing environmental. Chloride is prominent in crevice corrosion and pitting all.

Sulphate
Most raw water contains sulphate. Presence of sulphate aggravates corrosion and be objectionable in concentrating water high in calcium, as in evaporative systems.

Iron
Iron is normally found in soluble ferrous Iron. On contact with air oxidizing agents, iron is converted to ferric iron and iron insoluble hydroxides or oxides. It will support to growth of iron bacteria and sulphate reducing bacteria.

Silica
Silica is present in almost all minerals and is found in fresh water. Silica is objectionable at high concentration in cooling tower makeup, because at this uncertainty about its solubility limit. It is objectionable in boiler feed water makeup is not only because it may from a scale in the boiler itself, but also because it volatility's at high temperature and pressure and redeposit on turbine blades.

Conductivities
the specific conductivity of water is a measure of its ability to conduct an electrical current. It is important as a direct measure of total amount of dissolved minerals and gases in the water.

Total Dissolved Solids (TDS)

The term total dissolved solid refers to the matter that remains as residue upon evaporation of filtered water.

Corrosion, Scale & Deposit Control: Award-winning, patented PERFORMAX MILLENNIUM cooling water treatments, PERFORMAX & deposit control products and corrosion inhibitors improve heat transfer, minimize downtime, prolong equipment life and reduce total cost of operation. We provide orthophosphate, p9rophosphate, zinc, molybdenum based proven corrosion inhibitors. Tetrapolymer based scale control technology works efficiently in highly stressed condition. (high 4emperature, hardness) The PERFORMAX MILLENNIUM series of cooling water treatment was awarded The Chemical Processing magazine's prestigious Vaaler Award.

Microbiological Control: Oxidizing and non-oxidizing micro biocides are specifically designed to control microbiological fouling in cooling towers, exchangers and other system components. We offer a comprehensive line of oxidizing biocides, featuring chlorine dioxide and bromine technology. In fact, we designed, built and patented one of the first commercially available chlorine dioxide generators, the GENEROX TM chlorine dioxide generator system. We also offer a broad range of non-oxidizing biocide based on QUATS, Gluteraldehyde, Dichlorophene, Isothiozelene, MET, DBNPA & Algaestat and speciaIly designed sea water treatment program.

Legionella Risk Management: Our best practices Legion Ella Risk Management program provides a total system approach & addressing chemical, mechanical and operational a3pects of risk management.

TREATMENT	FOR
Chlorination	Controlling Microbiological fouling
Filtration	Prevention of fouling of heat transfer surface.
Sulfuric acid	Regulation of pH
CHEMICAL DOSING SYSTEM
Inhibitors	Protection of Metal from Steel/Copper corrosion.
Antiscalent	Precipitation of Alkaline earth salts
Antifoulant	Retarding deposition of corrosion products.

Reasons of fouling
Silt introduced by the make up water. Dirt from air. Reaction of residues from chemical treatment. Microbiological debris. Products produced by corrosion such as hydroxides and insoluble salts.
If fouling is not controlled, it will result in heavy deposits inside cooling water tubes, resulting in reduced tube diameter.
Fouling is controlled by side stream pressure filter/ Chlorination/ chemical dosing

SELECTION OF CAPACITY OF SIDE STREAM FILTER

% of reduction of undissolved solids.
(Select 80%)
t = Time desired for reduction in hrs.
(Select maximum in 48 hrs.)
b = blow down rate m3/hr
v = Total volume of cooling system M3

f = Side stream filtration rate m3/hr Example

For V = 6000 M3, t = 48 h,
b = 100 M3/h
Filtration rate = 100 M3/hr

MICRO – ORGANISM

Bacteria, algae & fungi present in cooling water circuit decreases the efficiency of heat transfer in cooling tower and condensers.
Chlorine is the most widely used chemical in industry as oxidizing agent for destruction and dissolution of micro-organisms.
Chlorination is effective only when cooling water pH is between 6 and 7.
COOLING WATER pH	% of HOCl for effective oxidation	RECOMMENDED DOSAGE
6	97	Free residual chlorine of minimum 0.5 ppm is recommended after meeting chlorine demand in C.W. sample analysis.
7	76
8	24
9	3
At pH 7 in C.W. System every 1 ppm Cl2 dosed only 0.76 ppm is used as oxidizing agent for control of micro organism.

GENERAL GUIDELINES FOR CHLORINE DOSE OF REASONABLY GOOD COOLING WATER.