Urea plant off-gases as fuel

[abutt116]

Our urea plant off gases contain 33% ammonia,
15% hydrogen, 08% oxygen and 44% nitrogen. I was thinking to burn these gases in primary reformer of ammonia plant as fuel.Is this possible? How ammonia could be removed from these gases to increase concentration of hydrogen without spending much money?

Thanks

 

[mbeychok]

abutt116:

Ammonia is very soluble in water. I think a simple water scrubber would remove a great deal of the ammonia.

Milton Beychok
(Contact me at www.air-dispersion.com)
.

 

[abutt116]

Thanks for reply.

Is the above mixture can be burn as it is? I heard that ammonia %age in air 16-30% is burnable. So the mixture of gases containing 33% ammonia, 15% hydrogen, 08% oxygen and 44% nitrogen will burn by mixing it with natural gas going to burners of primary reformer at ammonia plant or to the boilers of utility plant? what will be negative effects regarding burning process and environment.

Thanks.

 

[BenThayer]

if you have an ammonia plant and urea plant, you might also have a nitric acid plant? although catalyst is used to help force nh3 to nitric oxide, you can still get some NOx when burning ammonia. that would be one consideration on the environmental side of it.

do you use air for passivation of the urea reactor, that may be a source of a safety concern in the transport of the gas.

we tried to recover this same stream in our plant (+1000 MTPD Urea) and tried to use natural gas to ensure we always stayed above the flamable limits of the gas. we gave up finally due to difficulties with operational upsets. this was several years ago and typical of the fertilizer business, we went cheap on the controls.

good luck

 

[abutt116]

Our main purpose is to utilize 15-20% hydrogen (hydrogen is present in CO2 coming from ammonia plant) in the urea plant off gas as a fuel in the burners of ammonia plant primary reformer burners or in utility boiler burners as a fuel by mixing it with natura gas. My main cocern is the presence of 30-35% ammonia in the off gases and 40-45% nitrogen along with hydrogen. yes we give air for passivation of urea reactor and there is always a risk of explosive limit in the presence of hydrogen. We do have nitric acid plant but we are already using these off gases at our ammonium nitrate plant. Due to presence of 15-20% hydrogen in the off stream gases, idea was to use them as a fuel in above mentioned burners to save fuel instead of giving them to AN plant. My question is will they burn and what will be the negative aspects?

Thanks.