coating at smoke chamber / calciner and feed
pipes ?
pipes ?
Ted Krapkat
Ted Krapkat•• Hello Muhammad,Hello Muhammad,
The compounds which cause build-ups in the smoke box/calciner and feed pipes will be different The compounds which cause build-ups in the smoke box/calciner and feed pipes will be different depending on the following factors;-
depending on the following factors;- (a) The chemical balance o
(a) The chemical balance of chlorides, alkalis and sulphur in the hot meal.f chlorides, alkalis and sulphur in the hot meal. (b) Oxygen content in the g
(b) Oxygen content in the gases at the kiln inlet.ases at the kiln inlet. (c) Burning zone and calciner temperature. (c) Burning zone and calciner temperature.
Chlorides: Chlorides:
Alkalis (particularly potassium) preferentially react with chloride to form KCl and NaCl. Any Alkalis (particularly potassium) preferentially react with chloride to form KCl and NaCl. Any left over alkalis then react with SO2
left over alkalis then react with SO2 and oxygen to form alkali sulphates. Chlorides are far and oxygen to form alkali sulphates. Chlorides are far moremore volatile in burning zone than alkali
volatile in burning zone than alkali sulphates and will substantially evaporate and recirculate tosulphates and will substantially evaporate and recirculate to the back end of the kiln where they will be deposited on incoming meal. Some chloride will the back end of the kiln where they will be deposited on incoming meal. Some chloride will however escape with the clinker, and
however escape with the clinker, and if this amount is equal to the if this amount is equal to the amount of fresh chloridesamount of fresh chlorides entering the kiln with the raw meal,
entering the kiln with the raw meal, a balance will be maintained and a balance will be maintained and few buildups will occur.few buildups will occur. However, if the chloride input changes or
However, if the chloride input changes or the burning zone temperature increases these factorsthe burning zone temperature increases these factors will upset the balance and
will upset the balance and buildups will occur more frequently.buildups will occur more frequently.
Sulphates and Oxygen: Sulphates and Oxygen:
As mentioned before if akalis are in molar excess
As mentioned before if akalis are in molar excess of chloride they will react with SO2 andof chloride they will react with SO2 and oxygen to form alkali sulphates according to
oxygen to form alkali sulphates according to the following equation;-the following equation;- K2O + 2 SO2 + O2 --> 2 K2SO4
K2O + 2 SO2 + O2 --> 2 K2SO4
If insufficient oxygen is present in the kiln inlet gases, the
If insufficient oxygen is present in the kiln inlet gases, the reaction above will not reaction above will not occur and veryoccur and very little alkalis or sulphur will exit the kiln in the clinker. Instead, K2O
little alkalis or sulphur will exit the kiln in the clinker. Instead, K2O and SO2 levels in the and SO2 levels in the back back end of the kiln will increase rapidly causing the hotmeal to become sticky and heavily coat the end of the kiln will increase rapidly causing the hotmeal to become sticky and heavily coat the walls and other surfaces of the smokebox/calciner/meal pipes,
to have the residual alkalis and
to have the residual alkalis and sulphur in molar balance AND to ensure sulphur in molar balance AND to ensure at least 2-3% O2 at theat least 2-3% O2 at the kiln inlet.
kiln inlet.
If sulphur is in large molar excess of alkalis, sulphate spurrite build-ups c
If sulphur is in large molar excess of alkalis, sulphate spurrite build-ups c an form higher up inan form higher up in the preheater by reaction of C2S, CaO and SO3 ie;-
the preheater by reaction of C2S, CaO and SO3 ie;- CaO.SiO2 + CaO + SO3 --> 3 CaO.SiO2.SO3 CaO.SiO2 + CaO + SO3 --> 3 CaO.SiO2.SO3
Sulphate spurrite is stable at temperatures between 900 -1200 degC and causes buildups which Sulphate spurrite is stable at temperatures between 900 -1200 degC and causes buildups which are very hard and difficult to remove.
are very hard and difficult to remove.
Temperature: Temperature:
If the temperature in the burning zone
If the temperature in the burning zone is excessive, not only will more alkalis/sulphur andis excessive, not only will more alkalis/sulphur and chloride be evaporated from the clinker
chloride be evaporated from the clinker charge, but the kiln inlet temperaure is likely to charge, but the kiln inlet temperaure is likely to be toobe too hot as well. This can make
hot as well. This can make the hot meal even stickier (due to the hot meal even stickier (due to the low melting point of the low melting point of alkali/sulphate/chlorides eutectic mixtures (mp 500-600 degC) that occur i
alkali/sulphate/chlorides eutectic mixtures (mp 500-600 degC) that occur i n the hot meal. Then the hot meal. The result will be an increased tendency to
result will be an increased tendency to form buildups.form buildups. Regards,
Regards, Ted. Ted.
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IBRAHIMUnfollow Follow IBRAHIM IBRAHIMUnfollow Follow IBRAHIM IBRAHIM ABU AWWAD
IBRAHIM ABU AWWAD•• But what is the residual percent of chloride that will be preservedBut what is the residual percent of chloride that will be preserved in the produced clinker in this case, is it could be still below than 0.1 % as required in the
in the produced clinker in this case, is it could be still below than 0.1 % as required in the international standards.
international standards. 9 days ago
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TedUnfollow Follow Ted TedUnfollow Follow Ted Ted Krapkat
Ted Krapkat•• Hello Ibrahim,Hello Ibrahim, Each kiln system is unique.... Each kiln system is unique.... Without a bypass, the amount of
Without a bypass, the amount of chloride retained in the clinker depends largelchloride retained in the clinker depends largely on the totaly on the total input of chloride from the raw materials, AFRs and fuels... after accounting for any chloride input of chloride from the raw materials, AFRs and fuels... after accounting for any chloride leaving the stack(s). Some kilns may at times exhibit
leaving the stack(s). Some kilns may at times exhibit a so-called "detached plume" on a so-called "detached plume" on the stack.the stack. This is caused by ammonium chloride
This is caused by ammonium chloride leaving the kiln system in gaseous form and leaving the kiln system in gaseous form and condensing ascondensing as solid particles in the cooler ambient air. This can
solid particles in the cooler ambient air. This can represent a significant amount of chloriderepresent a significant amount of chloride leaving the system, which can potentiall
leaving the system, which can potentially pose a serious environmental problem.y pose a serious environmental problem.
With a bypass installed, the chloride in the clinker
With a bypass installed, the chloride in the clinker is determined by the amount of is determined by the amount of kiln gaseskiln gases bypassed and the quantity of chloride contained in them.
bypassed and the quantity of chloride contained in them.
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tweet this tweet this Share Discussion Share Discussion Latest Updates Latest Updates Sagar Raysoni
Sagar Raysonilikes thislikes this commentcommentby James Kellyby James Kelly
Suitable materiel for temp range 1100-120 degree Centigrade and properties of
Suitable materiel for temp range 1100-120 degree Centigrade and properties of weldable andweldable and fabricated also.
fabricated also.:: I suspect that no customers ask for 353 MA as it was never promoted in IndiaI suspect that no customers ask for 353 MA as it was never promoted in India and is no
and is no longer made. Until Outokumpu ceased production...longer made. Until Outokumpu ceased production...
o o Like (2)Like (2) 2 hours ago 2 hours ago Sagar Raysoni
Sagar Raysonilikes thislikes this commentcommentby arun raoby arun rao
Suitable materiel for temp range
Suitable materiel for temp range 1100-121100-120 degree Centigrade and properties of 0 degree Centigrade and properties of weldable andweldable and fabricated also.
fabricated also.:: James, I agree with your comments. On a few ocassions I had recommendedJames, I agree with your comments. On a few ocassions I had recommended using HT or HU grades with a life guarantee. The plants were...
using HT or HU grades with a life guarantee. The plants were...
o
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Kacie Brinker
Kacie Brinkerstarted a started a discussion:discussion: Seeking a Safety Manager for a Seeking a Safety Manager for a national cement producer.national cement producer. The position is based on the
The position is based on the eastern half of the United States.eastern half of the United States. o
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