5 replies to this topic

[krishanan]

Dear sir,

 

I want to know how to calculate unburned hydrocarbons in natural gas fired boiler as i want to set range of HC analyser.

 

However in general there wont be hydrocarbons presented in the flue gas due to complete combustion, but one of our customer insisting to put HC analyser at chimney to measure the hydrocarbons.

 

Please let me know how to calculate the unburned hydrocarbon so that i can select the range for HC analyser Your quick response is appreciable.

Edited by krishanan, 03 April 2013 - 04:14 AM.

[thorium90]

If you are already operating at sufficient excess air, then ppm range of hydrocarbon would easily satisfy this problem. Like you have said, you would not expect unburnt HC. Also, due to safety issues of large quantities of large releases of unburnt HC, you likely already have interlocks preventing such a scenario.

[jrtailor09]

You should provide SOX & NOX anlyzer instead of HC analyzer.

 

You are designing the furnace considering the complete combustion. 

 

if something is available, I will share with you.

 

Regards,

Jatin

[amirali1572]

Hi Dear

if you work in 2 to 3.5 % or higher excess O2 in flue gas you can sure than no HC exist in flue gas and you can mesure O2 and HxCy by TESTO portable analyzer.

[krishanan]

Thank u all for spending your precious time to reply.

 

I know if i maintain execess O2 in flue gas in the range of 3 - 3.5 % there wont be any unburnt HC in flue gases, however client is insisting to provide HC analyser in flue gas(at Stack), but i am unable to know how to fix the range of analyser and which hydrocarbon needs to be measure like methane/eathane etc....

[Atttyub194]

Dear All  

Good day!  

 

It is correct that generally there is no need of installing HC  and normally , it is very difficult to maintain an online analyzer in the field and to be very honest,  I have not seen such an analyzer installed in filed for such monitoring for power boilers or furnaces operating on Natural gas.  

 

The objective for such installation is not clear at least to myself and when you go a techno economical study you may not find it economical  

 

I have specified  oxygen and combustion analyzer i.e. basically CO analyzer , which were in turn used to reduce excess oxygen thereby increasing the efficiency of combustion/ boiler .  

 

Flue gas analyzers  now available have fuel types and their chemical compositions programmed in its' memory. Therefore, when the analyzer is used to to measure flue gas temperatures and either the O2 or CO2 levels, it instantly and automatically calculates and displays boiler efficiency. Accordingly, option for adjusting the setting to maximum efficiency are available and we as design engineer normally provide such option , however, operators prefer to adjust the parameters manually.  

 

Acid dew point analyzer may be an other source of fuel economy, however, I personally prefer to do manual adjustment with safety margin of at least 10-20 Deg C due to huge implication in case of malfunctioning of analyzer

 

 

Regarding your query for range , it may be selected using chart attached starting from maximum to minimum and analyzer are available in market with this range. However, for CO analyzer the optimum range is ( 0~3000 ppm)  

 

 I am attaching one more document by one of the CO analyzer manufacturer  for your information, which may be helpful for you

 

 

  Best regards and God Bless You  

 

Ahmed Attyub

 Comb_Presntn_CCO_5500_TrainCust_200701.pdf   260.13KB   6 downloads

Edited by Attyub194, 14 April 2013 - 11:24 AM.