Boiler, feed tank, condensate, Improvement, condensate

1. Proposed ModificationsProposed Modifications
inin
Boiler Feed TankBoiler Feed TankBoiler Feed TankBoiler Feed Tank
By:
D K Singhal
deveshksinghal@gmail.com

2. Conventional Boiler Feed TankConventional Boiler Feed Tank
The fundamental object of having a boiler
feed tank is to ensure uninterrupted
supply of boiler feed water to the boiler.
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3. Problems with Existing TankProblems with Existing Tank
A boiler feed water tank is generally a
huge tank suitable of storing sufficient
feed water for 3-4 hours of operation.
That is why, it cannot be kept pressurizedThat is why, it cannot be kept pressurized
(or fully closed) easily and economically.
With open tank, flash vapors coming out
result in significant energy losses.
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4. Problems with Existing TankProblems with Existing Tank
Big size results in increased insulation
costs.
Furthermore, as the surface area is high,
heat losses are significant even after goodheat losses are significant even after good
insulation.
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5. Proposed ApproachProposed Approach
Proposed approach uses two separate
tanks connected to each other.
One tank contains cold makeup water,
and needs no insulation.and needs no insulation.
The second tank is relatively small, which
can be insulated easily and efficiently.
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6. Cold Make Up Water TankCold Make Up Water Tank
This tank can be made suitable sized to
hold adequate make up water in case
there is inadequate condensate supply.
The elevation of this tank is as per theThe elevation of this tank is as per the
boiler designer recommendations, as its
head will give sufficient NPSH to feed
pump.
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7. New Small Hot CondensateTankNew Small Hot CondensateTank
The proposed small hot condensate tank
is a small tank strategically placed in the
circuit.
Its capacity should be adequate forIts capacity should be adequate for
typically 15-20 minutes of operation.
As the size is substantially small, it can be
properly insulated.
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8. New Small Hot CondensateTankNew Small Hot CondensateTank
This tank has an outlet to boiler feed
pump near the top.
The make up water enters the tank at the
bottom.bottom.
At extreme top, there is a small venting
line that vents flash vapors generated by
condensate to the top of cold make up
water tank.
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9. The SchemeThe Scheme
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10. Small TankSmall Tank
The small tank is a closed vessel in which
hot condensate enters from the top.
The condensate is removed from top,
thus, hotter condensate goes to boilerthus, hotter condensate goes to boiler
feed pump.
In case condensate supply is lesser than
that required by boiler feed pump, cold
makeup water enters from the bottom.
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11. Small TankSmall Tank
Thus, the cold water enters the boiler if
and only if all hot condensate has been
consumed.
As the make up supply is without a valve,As the make up supply is without a valve,
there is no risk of tank becoming empty
and dry run of boiler feed pump.
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12. Small TankSmall Tank
In case the boiler feed pump is off, and
condensate is coming from process, the
same pushes the colder water at the
bottom of small tank back to the mainbottom of small tank back to the main
feed water tank through make up line.
Even if some hot condensate is pushed
back through this line, this returns back
when the pump is restarted.
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13. InsulationInsulation
The small tank and the make up water
line (as it may get flooded with hot
condensate occasionally) needs insulation.
Being this tank much smaller, you canBeing this tank much smaller, you can
insulate it well.
Typically, the insulation costs are reduced
to just 15-20% only.
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14. Main Feed Water TankMain Feed Water Tank
This way, the main feed water tank
remains at lower temperature, and hence
no insulation is required.
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15. ThankYou.ThankYou.
D K Singhal
+91-9412713426
deveshksinghal@gmail.com
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