BOILER WATER TREATMENT
Why do you treat boiler water? Can boiler operate without having boiler feed water treated?
What are impurities in boiler water?
What are impurities in boiler water?
What are the effects of impurities in the boiler water?
What is internal and external water treatment?
What causes temporary hardness?
What causes permanent hardness?
Describe how the hardness levels are controlled.
Describe how does lime and soda ash react in the softening process? What are the various methods of lime softening? Discuss what are the advantages and disadvantages of lime soda softening.
Draw a typical setup of a water treatment plant in a palm oil mill.
What are coagulation and flocculation? What are the chemicals used in the process?Why is soda ash added at the clarifier before coagulant is added?
With the aid of a diagram, describe the operation of water clarifier.
What are the functions of sludge blanket in the operation of clarifier?
What is the purpose of a sand filter? Draw a pressure sand filter and describe how it works.
When should you backwash the sand filter?
What is the purpose of softener? Draw a softener and describe how it works.
What is fouling, and what substances can “foul” the ion-exchange resins of a softener?
What are the benefits of open feedwater heater?
What is a mixed-bed demineralizer? Describe its principle of operation.
What is regeneration of polisher?
What is the external treatment to remove oxygen from boiler feed water? Why does it require to externally remove oxygen since the boiler already incorporates chemical treatment to remove oxygen?
Draw a pressurized deaerator complete with ancillaries and describe how it works.
Draw a tray-type deaerator and describe its operation.
Draw a vacuum deaerator and describe its operation.
What can indicate the good performance of a deaerator?
How do you know if the deaerator has malfunctioned?
Can you measure the content of dissolved oxygen in the feed water to check for deaerator performance? If yes, what are the precautions?
How do you know the amount of steam required to heat and deaerate the water? Is tray-type and pressurized type consumes different amount of steam at similar feed water flow rate?
What are the boiler water parameters at your plant? Indicate the permissible range and why are they important?
What are the recommended TDS limits in the boiler?
What are the tests required for boiler water?
Why is water analysis results expressed as CaCO3?
What are the chemicals used for treating boiler water?
Briefly explain the types of chemicals used in internal boiler water treatment.
What is magnetite on boiler steel?
How do you maintain magnetite?
Why pH between 10.5 and 11.5 is ideal in boiler water?
What is the effect of pH on corrosion?
How corrosion is controlled in ‘once-through’ supercritical boiler?
How oxygen enters the boiler?
What are the chemicals used to prevent oxygen corrosion in the boiler?
Why DEHA is a better oxygen scavenger compared to sulfite? What are the advantages and disadvantages of using hydrazine for feed water treatment?
What are the chemicals used to protect condensate return line from corrosion and where are they added?
Can you use sodium sulfite as an oxygen scavenger at higher steam pressure? What does phosphate do in a boiler?
How is carbonic acid formed in the condensate system?
What causes corrosion in condensate system? What is the purpose of an electric conductivity or TDS test of boiler water?
What is the relationship between e-conductivity and TDS?
What is alkalinity? Is alkalinity and pH the same?
What is M-alkalinity in boiler water test result?
What is P-alkalinity in boiler water test result?
How do you interpret the results from alkalinity test?
What is the permissible level of alkalinity in boiler water?
What are chlorides in boiler water?
Why is chloride indication in boiler water and feed water of importance? Why silica in boiler feed water is bad?
How do you control silica in boiler water?
What is scale? Is scale different from sediment?
Can you measure the thickness of scale on boiler tubes or surfaces?
Several types of powders or flakes (scales) will be presented before you and the examiners normally ask you to identify the type of deposit. It is good to remember the characteristic of each deposits as listed here:
How do you measure Total solids (TS)?
What is boiler blowdown in term of water treatment?
How many types of blowdown are there and describe each type in detail.
What is the difference between slightly soluble solids and insoluble suspended solids? Give examples in your answer.What is continuous blowdown (CBD)?
Where is continuous blowdown valve located?
What is automatic blowdown?
Why it is important to control blowdown?
How do you calculate the blowdown rate for a boiler with an evaporation rate of 10 ton/hr, if the maximum permissible TDS in boiler water is 2,500 ppm with 20% makeup water? The TDS of feedwater is 200 ppm.
What is intermittent blowdown (IBD)?
What is the danger of oil in boiler water?
How does oil enter boiler water? And what you should do once oil is detected in boiler water?
Can you notice oil from watching the gauge glass?
From the deaerator level gauge glass, you noticed a presence of oil. What should you do?
What are the dangers of water carryover?
What is cycle of concentration? How do you calculate cycle of concentration for boiler water?
What causes carryover?
What is foaming and what are the causes?
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