1. Power Plant Chemistry
Phosphate Use & Safety Precaution
Prepared By : -
Umar Farooq
Chemist “A” Chemical Section
MSc ( Chemistry ) MBA (HR & Marketing )
107301@se.com.sa
umar7325@yahoo.com
SEC Shoaiba Jeddah
Saudi Arabia 1
Mineral
Analysis
Deposit
Analysis
Microbiological
Analysis

2. Power Plant Chemistry
 Topic for Discussion
 Type of Hardness
 Internal Water Treatment
 Phosphate Treatment
 Tri Sodium Phosphate
 Phosphate Hideout
 Hazardous Information
 First Aid Measure
 Handling and storage
 Toxicological Information

3. Types of Hardness
Temporary Hardness ( Alkaline Hardness )
 It is due to presence of bicarbonates of calcium
and magnesium in water , also called carbonate
hardness. It can be removed by boiling and
pretreatment process
Permanent Hardness(Non Alkaline Hardness )
 It is due to presence of chlorides , sulphate and
nitrate of calcium and magnesium , it can be
remove by ion exchange and desalination
process
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4.  The term internal water treatment describe
the reaction induced with in the boiler
system to render the water less harmful to
system operation .
The main features of internal
water treatment are summarized on the
above slide.
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Internal Water
Treatment

5. Internal Water Treatment
Prevention scale by
1) Ether precipitating chelating the hardness in water
2) Maintaining the sufficient alkalinity for appropriate
chemical reaction.
3) Sludge conditioning to keep the suspended particle in
non adhering state.
4) Maintaining total dissolve solid with in limit.
Prevention of Corrosion.
In Boiler by
1) Scavenging oxygen formulation of protective film .
2) Maintaining sufficient alkalinity neutralizing CO2
formulation of protective film.
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6. Phosphate Treatment
 Function of phosphate treatment is to reduce the
effect of hardness producing salt and
maintaining them a non adherent sludge rather
than to deposited and then removing the excess
sludge [Ca3 ( Po4 )2] by below down.
Various forms phosphate
alkalinities are used boiler treatment listed below
 Na3PO4 + Boiler drum [Ca3 ( Po4 )2] + Protective layer
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7. Phosphate Treatment
1) Na3Po4 + H2O Na2HPo4 + NaOH
2) Na2HPo4 + H2O NaH2Po4 + NaOH
3) NaH2Po4 + H2O H3Po4 + NaOH
4) H3Po4 + H2O 3H + + Po4 +3
Tri Sodium Phosphate Na3Po4
Di sodium phosphate Na2HPo4
Mono sodium phosphate NaH2Po4
Phosphoric acid H3Po4
Hexa mete phosphate [Na3Po3]6
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8. Tri Sodium Phosphate
React with Ca++ and Mg++ salt ( if present in
boiler water ) to form [Ca3(Po4)2] and [Mg3(Po4)2] which
precipitate as sludge.
 Na3Po4 + 3CaSo4 3NaSo4 + Ca3(Po4)2
 Na3Po4 + 3MgSo4 3NaSo4 + Mg3(Po4)2
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Monocalcium phosphate, Dicalcium phosphate, Tricalcium phosphate,

9. Tri Sodium Phosphate
When it is required to reduce the concentration of NaOH in
boiler water mono sodium phosphate and hexa meta
phosphate can be used
 Na2HPo4 + 2NaOH Na3Po4 + 2H2O
 [Na3Po3]6 + 12NaOH 6 Na3Po4 + 6H2O
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Monosodium phosphate Sodium hexametaphosphate

10. Tri Sodium Phosphate
Excess dosing of phosphate result Mg3(Po4)2
formation of Mg content is high in boiler water . This
magnesium phosphate form a sticky sludge so its
formation must be avoided by maintaining proper
phosphate and alkalinity ratio.
 MgCl2 + 2NaOH Mg3(OH)2 + 2NaCl4
 MgCl2 + Sio2 + 2NaOH MgSio3 + 2NaCl4 + H2O
Magnesium silicate also tends
to change into scale if the pH of the boiler water is too
low . Silica scale is very hard to remove and have high
resistance to heat transfer silica ( Sio2) can be stabilized
in the boiler water is about 2 time of silica concentration .
There fore both the pH of boiler water and phosphate
concentration must be applicable for the prevention of
silica in boiler. Umar Farooq Chemist “ A “
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11. Phosphate Hide Out
Temporary deposition of water soluble
chemical e.g. Na3PO4 during normal boiler operation is
called as “ Hideout “This phenomena is some time
found in high pressure boiler . Due to change in heat flux
loss of Na3PO4 accurse in boiler water however if load is
reduce phosphate re dissolve and again appear although
a number of substance exhibits.
This phenomena Na3PO4 is must be interest
in boiler operation . At temperature between 300 to 350
C* . Tri sodium phosphate exhibits an interrogate
solubility . Its solubility is reduced at high temperature
and precipitates out on the boiler tube and than
disappears from boiler water when boiler or pressure
reduced. It is again dissolved and appear in the solution
form. Umar Farooq Chemist “ A “
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12. Hazard Identification
Inhalation
Material is irritating to mucous membranes and upper
respiratory tract. Exposure can cause coughing, chest pains and
difficulty breathing,
Skin Contact / Absorption
May cause moderate skin burns. May cause
severe irritation, especially if skin is moist or wet.
Eye Contact.
May cause eye burns. May cause permanent corneal
injury. May cause severe eye irritation.
Ingestion.
May cause burns of the mouth, throat and stomach.
Aspiration in to the lungs may occur during ingestion or vomiting,
resulting in lung injury.
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13. First Aid Measures
Inhalation .
Remove victim to fresh air. Give artificial respiration only if
breathing has stopped. If breathing is difficult, give oxygen. Seek
medical attention if difficulties persist.
Skin Contact / Absorption.
Remove contaminated clothing. Wash affected
area with soap and water. Seek medical attention if irritation occurs
or persists.
Eye Contact.
Flush immediately with water for at least 20 minutes.
Forcibly hold eyelids apart to ensure complete irrigation of eye
tissue. Seek immediate medical attention if symptoms persist.
Ingestion.
Do not induce vomiting. Do not give anything by mouth to an
unconscious person. Have conscious person drink several glasses
of water or milk. Seek immediate medical attention.
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14. First Aid Measures
Additional Information.
Treat symptomatically. Ingestion of large quantities of phosphate salts
(over 1.0 grams for an adult) may cause an osmotic catharsis resulting in diarrhea
and probable abdominal cramps. Larger doses such as 4-8 grams will almost
certainly cause these effects in everyone. In healthy individuals most of the ingested
salt will be excreted in the feces with the diarrhea and, thus, not cause any systemic
toxicity. Doses greater than 10 grams hypothetically may cause systemic toxicity.
Treatment should take into consideration both anionic and caution portion of the
molecule. The following treatments should be considered for the specific group(s) of
phosphate salts found in this product:
1) All phosphate salts, except calcium salts, have a hypothetical risk of hypocalcemia, so
calcium levels should be monitored.
2) Ammonium salts have a hypothetical risk of ammonia toxicity. In addition to calcium
levels, ammonia and phosphate levels should be monitored.
3) Potassium salts have a hypothetical risk of hyperkalemia which can cause cardiac
arrhythmia. In addition to calcium levels, potassium and phosphate levels should be
monitored. Also consider continuous EKG monitoring to detect hyperkalemia.
5) Sodium salts have a hypothetical risk of hypernatremia. In addition to calcium levels,
sodium and phosphate levels should be monitored.
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15. Handling and Storage
Handling Procedures
Avoid contact with eyes, skin and clothing. Avoid
breathing in dust. Use with adequate ventilation. Wash thoroughly
after handling. Potentially deadly carbon monoxide gas can form in
enclosed area or tanks when alkaline products contain materials that
contain sugars. Do not enter such areas until they have been well
ventilated and carbon monoxide and oxygen levels have been
determined safe. Continue to monitor atmosphere while personnel
are in enclosure. Empty containers may contain hazardous product
residues.
Storage Requirements.
Store in a cool, dry, well-ventilated area.
Keep containers tightly closed
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16. Personal Protection and Exposure Controls
Protective Equipment
Eyes. Chemical goggles, full-face shield, or a full-face respirator is to be worn
at all times when product is handled. Contact lenses should not be worn;
they may contribute to severe eye injury.
Respiratory ,NIOSH-approved respirator for dust should be worn, if needed.
Gloves, Impervious gloves of chemically resistant material (rubber or PVC)
should be worn at all times. Wash contaminated clothing and dry thoroughly
before reuse
Clothing ,Body suits, aprons, and/or coveralls of chemical resistant material
should be worn at all times. Wash contaminated clothing and dry thoroughly
before reuse.
Engineering Controls
Ventilation Requirements, Mechanical ventilation (dilution or local exhaust),
process or personnel enclosure and control of process conditions should be
provided. Supply sufficient replacement air to make up for air removed by
exhaust systems.
Other, Emergency shower and eyewash should be in close proximity.
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17. Toxicological Information
Irritancy.
Irritating to skin & respiratory area, extremely
irritating to eyes.
Chronic/Acute Effects
Inhalation of product may aggravate existing
chronic respiratory problems such as asthma,
emphysema or bronchitis. Skin contact may aggravate
existing skin disease.
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