Oxygen Measured in Boiler Stacks -- Is the captured value true or false ?
Consider the Reaction C + O2 --> CO2, the following conditions are available in the furnace
Condition Carbon Oxygen Carbondioxide Reaction
1 Reactive Reactive 100% probability Successful
2 Reactive Non-reactive 0% probability Fail
3 Non-reactive Reactive 0% probability Fail
4 Non-reactive Non-reactive 0% probability Fail
In the boiler furnace only 25% probability exists for a successful carbon & oxygen reaction.
What if conditions 2, 3 & 4 are present in the furnace, then the following is probable
a) Carbon showing up as LOI
b) Reaction failure O2 shows up as a component of excess air
Hence the indication of O2% in stack, may not be true if the reaction conditions are not examined & also if LOI is present.If LOI is present, the fact is that there is reaction failure O2 showing up as excess air.
So, what is excess air now ?. True excess air is obtained only when the LOI is near zero, till then it is only a mixture of excess air + reaction failure O2.
How do we achieve true excess air ?
Can be achieved by synchronizing 3T's, time, turbulence & temperature.
In 3T alignment, the reaction condition 1, prevails.
There are 27 types of Boiler Operation combinations considering
1) PA or FD Fan, SA Fan & WBP for CFBC boilers
2) PA Fan, FD Fan & WBP for AFBC boilers
3) FD Fan, SA Fan & Bed thickness for Stoker boilers
4) PA Fan, FD Fan & WBP for PF boilers
In 26 Boiler operation combinations conditions, improper reaction conditions reign & reaction failure O2 shows up as excess air.
How to recognize, that the O2% indication is true excess air ?
If
1. LOI is near zero for CFB & PF boilers
2. LOI is < 2% for AFBC & FBC boilers
3. LOI is < 4% for Stoker Boilers
4. Direct Method efficiency is 1.5% to 2% less than Indirect Method Efficiency
5. No adjustments made for CV of coal, Coal quantity or Steam quantity & real data has been considered
6. 3T's are in alignment
If you have any questions on the same, write to me at sap@chargewave.in
Thanks for reading
PS Anand Prakash
Consider the Reaction C + O2 --> CO2, the following conditions are available in the furnace
Condition Carbon Oxygen Carbondioxide Reaction
1 Reactive Reactive 100% probability Successful
2 Reactive Non-reactive 0% probability Fail
3 Non-reactive Reactive 0% probability Fail
4 Non-reactive Non-reactive 0% probability Fail
In the boiler furnace only 25% probability exists for a successful carbon & oxygen reaction.
What if conditions 2, 3 & 4 are present in the furnace, then the following is probable
a) Carbon showing up as LOI
b) Reaction failure O2 shows up as a component of excess air
Hence the indication of O2% in stack, may not be true if the reaction conditions are not examined & also if LOI is present.If LOI is present, the fact is that there is reaction failure O2 showing up as excess air.
So, what is excess air now ?. True excess air is obtained only when the LOI is near zero, till then it is only a mixture of excess air + reaction failure O2.
How do we achieve true excess air ?
Can be achieved by synchronizing 3T's, time, turbulence & temperature.
In 3T alignment, the reaction condition 1, prevails.
There are 27 types of Boiler Operation combinations considering
1) PA or FD Fan, SA Fan & WBP for CFBC boilers
2) PA Fan, FD Fan & WBP for AFBC boilers
3) FD Fan, SA Fan & Bed thickness for Stoker boilers
4) PA Fan, FD Fan & WBP for PF boilers
In 26 Boiler operation combinations conditions, improper reaction conditions reign & reaction failure O2 shows up as excess air.
How to recognize, that the O2% indication is true excess air ?
If
1. LOI is near zero for CFB & PF boilers
2. LOI is < 2% for AFBC & FBC boilers
3. LOI is < 4% for Stoker Boilers
4. Direct Method efficiency is 1.5% to 2% less than Indirect Method Efficiency
5. No adjustments made for CV of coal, Coal quantity or Steam quantity & real data has been considered
6. 3T's are in alignment
If you have any questions on the same, write to me at sap@chargewave.in
Thanks for reading
PS Anand Prakash
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