Firetube Boiler Carryover

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Taxonomy

• Cooling Boiler & Wastewater
• Industrial Water Treatment
• Industrial Water Treatment
• Industrial Water Managment
• Industrial

9 Answers

1. Hello,Improper boiler operation and monitoring will cause carryover.If the water level in the boiler is dropping, or the pump seems to cavitate for no reason,
   check for carryover. It may explain what is happening. I can say  most common mechanical causes of carryover are operation in excess of design load and sudden increases in load.

2. Considering all previous answers could be correct, there is also the possibility of tubes with incrustations on areas not well cleaned... the effect of heat transmission is of great importance, specially on the deepest section of tubes.

3. Another potential factor not mention is response of level control with boiler feed water pump rate control (could be swinging by oscillation of feed control valve, perhaps.  This is something to consider if other factors have been rules out, such as wild load swinging, firing rate oscillation, etc.

4. Mr. McDonald,

   In other words, there are lots of reasons that you could be getting boiler water carryover into your steam feed. Start with the simplest issues to resolve, test your boiler feed water and condensate return. After that, verify that your level control switches and pumps are working correctly. Watch your steam pressure and temp trends to spot irregularities in usage throughout the day. (Maybe someone is switching steam feeds too fast?) The answer to this question could be as simple as a bad mix on your pre-treat chemicals or opening steam lines too fast.

5. Fire tube boilers are generally low pressure boiler. One key reason for carryover in fire tube boiler is the entrained boiler water in steam carrying impurities 

6. Following reasons. .

   Over loaded boiler.

   Bad quality of feed water.

   Sudden fluctuation in load

   Manual inperfect, disconutinuous combustion and fuel feed.

   Inperfect condensate collection and piping    

   1 Comment

   1. Many don't understand how boilers are rated.  It is called a from and at rating and is based on a feed temperature of 100 C.  These temperatures cannot be practically maintained.  Therefor feed temperatures lower than 100 will reduce the boiler rating as feed temperatures are dropped.  Secondly, boilers are rated in kg per hour.  So a boiler rated at 6000 kg per hour will only produce 100 kg per minute.  If the steam demand exceeds this to say 150 kg in a minute then the boiler will prime and carry boiler water with it.  This is caused priming.  If the boiler pressure drops the same can happen.  The velocity of steam changes dramatically between 7.5 and 5.5 bar so if the pressure drops in the boiler then the speed at which steam can reach its use point is slower and can cause the boiler to prime.

      Foaming is caused by the things the other comments have been made.  The greatest cause of foaming is high TDS or high caustic levels.  If the pretreatment plant is not working properly, then hardness enters the boiler, which will increase the suspended solids within the boiler.  Once the suspended solids level exceeds a certain level, the water stops acting like water and acts more like a fluid with solids.  Then the boiler will foam.

7. In addition to the previous answers, foreign contaminants in the condensate return, such as fats, oils and greases.

8. High alkalinity, high dissolved solids, severe and abrupt load swings, and water level control

9. Higher than designed steam consumption, boiler water quality and boiler design.