Purity of CO2 after regeneration.

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samiran3051
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Purity of CO2 after regeneration.

Post by samiran3051 » Thu Jun 06, 2019 12:19 pm

I am working at ammonia plant as designed by HTAS. we have gas purification having benefield solution system. Now a days we are facing a problem regarding the purity of Carbon dioxide. Earlier we got it of 99% but it is now 96%. Can anyone suggest or find out the reason behind the problem. Showing Hydrogen of 2.3%

omkarpatil
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Re: Purity of CO2 after regeneration.

Post by omkarpatil » Mon Jun 10, 2019 11:44 am

Hydrogen percentage indicates the possibility of leakage in Benfield reboiler.


omkarpatil
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Re: Purity of CO2 after regeneration.

Post by omkarpatil » Tue Jun 11, 2019 10:54 am

Increase in the hydrogen concentration in C02 will increase the requirement of passivation air to maintain O2 concentration in CO2 since some portion of O2 gets consumed in the hydrogen removal reactor. This will also increase the CO2 compressor power requirement to some extent as the volumetric flow through compressor had increased due to the increased concentration of hydrogen in CO2 and addition of extra quantity of passivation air. This will be evident from increase in the compressor speed.
Inerts from Urea wash section may be analysed for explosive range.

chinh
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Re: Purity of CO2 after regeneration.

Post by chinh » Thu Jun 20, 2019 4:12 am

I think, you should check reboiler leakage.
Take sample from top stripper.

bedmonds
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Re: Purity of CO2 after regeneration.

Post by bedmonds » Mon Jun 24, 2019 11:51 pm

It's not uncommon to suffer leakage in the Benfield steam generator located upstream of the reboiler. It's possible to check as follows:
make a cooler with 1/4" SS tubing in a pail of water
run the steam through the cooler and into full inverted graduated cylinder in a beaker of water
the steam will be the increase in beaker contents and the gas will be the volume in the inverted graduated cylinder
A common cause is (I think) concentration of K2CO3 in the first baffle compartment and reversion to KOH which can attack the stainless steel tubes
I'm not familiar with reboiler tube leakage but that doesn;t mean it's not a distinct possibility-but I'd suspect the steam generator first and the syngas goes with the steam to the Lo-Heat ejectors

pbaboo
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Re: Purity of CO2 after regeneration.

Post by pbaboo » Sat Jul 06, 2019 2:33 pm

In CO2 Hydrogen percentage indicates the possibility of leakage in Benfield reboiler.It is very dangerous in Urea Plant, MP section. The risk of explosion mainly due to H2/O2 mixtures. If No hydrogen removal in Urea Plant then then in MP section vent get explosion. The leakage in reboiler may be attended as soon as possible. Hydrogen exists in varying quantities as a component of flammable gas streams throughout the ammonia complex presenting the potential for explosions either internal (resulting from ingress of air) or external (from leaks). In the HP section (stamicarbon Process) and MP section in Saipem Process section of urea plants numbers of explosions are reported to have occurred involving explosions, which were thought to be caused by Ignition of hydrogen and oxygen present in the gas streams. Several operators of similar plants experienced explosions in the scrubber prior to the introduction of the catalytic hydrogen removal process.
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gschulz
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Re: Purity of CO2 after regeneration.

Post by gschulz » Thu Oct 03, 2019 3:48 pm

Dear Sir, please be aware that higher H2 content to CO2 plant will increase the area of explosive mixture at the triangular diagrame at inert wash column. If you increase passivation air this will be even worse. High H2 content can also be a consequence of deficient performance at HP flash (I asume that your HTAS plant has a BASF Co2 removal section). Have you increased amine concentration and or total semilean solution circulation?. we have had increased H2 slip at CO2 due to these changes. Best regards, G Schulz

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