Saturday, July 23, 2005

• Kribhco


Introduction
Process plants require various inputs for raw material conversion. Plants that provide these inputs and located away from the battery limit of process plants are called offsites facilites. Offsites facilities of an ammonia urea fertilizer plant are:

 Water pretreatment plant.
 Cooling water supply system.
 Dm plant.
 Nitrogen plant.
 Instrument air and service air supply.
 Ammonia storage and handling.

Our report will cover only one facility of Offsites facilities it’s (DM plant)

As you know water used for drinking should be free from Bacteria, excessive hardness, harmful chemicals and radioactive element. For aesthetic reasons water should free from objectionable testes, color and odour which are the of contribution of dead microorganisms and chemical impurities.

• Actually raw water contents :

 CATIONS
 Na+
 Mg++
 Ca++

 ANION
 Cl-
 SO4 –
 SiO2
 CO3-







In DM plant we removing all this impurities and dissolved salts from the water by using (Ion exchange)




As you see this diagram show as the main components about DM plant:

 Activated carbon filter. 5 units (ACF).
 Strong acid cation. 4 units (SAC).
 Degasser Tower.
 Weak basic anion. 4 units (WBA).
 Strong basic anion. 4 units (SBA).
 Mixed bed. 4 units.
 DM water storage tank. 3 tanks.
 RCST storage tank. 2 tanks.








 ACTIVATED CARBON FILTERS



Activated carbon filter received water from Filtered water tank which have three centrifugal pumps. These pumps one in line and two standby.
In Activated carbon filter we removed chlorine

During Services mine:
o the normal operation (removed of cation by resin)
During Regeneration it has two main goals:
o To remove trapped particles or fines while leaving behind the good resin.
o To expand and resort compacted resin beds








 STRONG ACID CATION



In this unit we removed the cation salts from the water like Na+, Mg++ and Ca+.

Some reaction during Service OF (SAC):

• R-H + NaCl R-Na + HCL

• 2R-H + CaCl2 R2-Ca + 2HCL










Some reaction during Regeneration OF (SAC)


• R- HSiO3 + NaOH R- OH + NaHSiO3

• R2- SO4 + 2 NaOH 2R-OH + Na2SO4































 DEGASSER TOWER



The purpose of degasser tower is to absorb CO2 from the water by air.
Degasser tower consist of:
 four towers and
 Sex blowers.

For each two towers three blowers two in line and one standby.
The operation don when blowers passing air inside the towers from bottom side and water coming from top side. By this way air will removed CO2 when contact with water.






 STRONG AND WEAK BASE ANION


In weak base anion we removed anion from water like: Cl-,SO4--,SiO2 and CO3--.

ANION REACTION DURING SERVICE (WBA):

• R- OH + H2SiO3 R- OH + NaHSiO3
• 2R- OH + H2SO4 R2 - SO2 + 2H2O

ANION REACTION DURING REGENERATION (WBA)

• R- HSiO3 + NaOH R- OH + NaHSiO3
• R2- SO4 + 2 NaOH 2R-OH + Na2SO4



 MIX BED


• During service :

The figure given above is a simplified illustration of a mixed-bed ion exchanger. A mixed-bed exchanger removes both cations and anions at the same time. IT has an additional distribution header, which is called a collector.


• During regeneration:

When the cation resin and the anion resin are regenerated at the same time, the two regenerants are fed in at the same time, and they both flow out of the ion exchanger through the collector.






 Specification of Demineralisation water:

 Free from hardness.
 Conductivity less than 0.1mmhos/cm.
 Contain silica less than 0.01ppm.
 pH from 6.8 to 7.3 .

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