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5

Quenching By Water Or Oil


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#1 CHEMSTRONG

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Posted 21 July 2022 - 02:54 AM

Dear Sir,

 

I wanted to know what is diff between quenching of process stream by oil and by water ? 

What is the difference ?

 

Please advice. I know Water quench is more effective way for heat transfer than that of oil quench .

 

Please elaborate further now.

 

Best Regards,

CHEMSTRONG 



#2 horatorres

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Posted 21 July 2022 - 10:20 PM

Process will define your best quench fluid.

 

Horacio



#3 fallah

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Posted 22 July 2022 - 01:53 AM

 

I wanted to know what is diff between quenching of process stream by oil and by water ? 

What is the difference ?

 

Please advice. I know Water quench is more effective way for heat transfer than that of oil quench .

 

 

Hi,

 

In general, for high temperature process streams if quenching by water will lead to having steam (phase change), at first it should normally be quenched by oil and then by water if required.



#4 breizh

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Posted 22 July 2022 - 07:21 AM

Hi,

More information about your stream is required .

Good luck

Breizh



#5 CHEMSTRONG

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Posted 23 July 2022 - 10:44 AM

Hi Fallah,

 

Thanks for your reply on this.

 

In my case, Furnace outlet is at 835 Deg C and they are using quench oil and water as well. In which case, we should use both and which case we should use only quench water as HT medium here??

 

For Ethylene Plant Furnace Outlet Quenching 

 

Thanks.

 

Best Regards,

CHEMSTRONG 



#6 fallah

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Posted 24 July 2022 - 02:27 AM

 

In my case, Furnace outlet is at 835 Deg C and they are using quench oil and water as well. In which case, we should use both and which case we should use only quench water as HT medium here??

 

For Ethylene Plant Furnace Outlet Quenching 

 

 

Hi,

 

Although the temperature of the stream outgoing from Olefin Furnace is normally higher than 800 C, the temperature of the same stream incoming to fractionation/cooling area after passing through the TLEs,...is normally lower than 200 C.

 

In the field of Olefin Plant, for liquid Feeds the cracked gas at first is normally to be cooled by produced quench oil and then by water; and for Ethane (Gas) Cracker the cracked gas is being cooled just by water.



#7 CHEMSTRONG

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Posted 24 July 2022 - 10:28 AM

Hi Fallah,

 

I know all these points but want to know this( quench Oil for Liquid Feeds and Quench Water is for Gas Crackers)  is due to Design and Heat Pinch reasons ?? 

 

Why we can not use only quench water for all feed types here like Liquid feeds and gas feeds etc??

 

Regards,

CHEMSTRONG 



#8 Pilesar

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Posted 24 July 2022 - 08:33 PM

Chemstrong, why do you want to use only quench water in your ethylene plant when operating with liquid feeds? What advantage have you found with that design? What do you plan to do with all the hot quench water? Please explain the expected process improvement. You mention heat pinch. What does your pinch analysis show?



#9 fallah

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Posted 25 July 2022 - 04:16 AM

 

Why we can not use only quench water for all feed types here like Liquid feeds and gas feeds etc??

 

 

Hi,

 

This is mostly due to significant difference of TLEs outlet temperature between liquid (Heavy Liquid or Light Naphtha) and gaseous Feedstocks.

In liquid Feedstock, for potential risk of coke formation due to droplet condensation, the TLEs outlet temperature cannot be brought lower than, say, 300C while in gaseous Feedstock such temperature can be well lowered due to lack of the mentioned potential risk.

 

Hence, it's obvious a high temperature cracked gas of liquid feedstock (~300 C-~600 C) incoming from TLEs cannot directly be quenched by water in a low pressure quench water column and at first has to be quenched with a higher boiling point cooling media, say quench oil, and then by water.

 

For a lower temperature (less than 200 C) cracked gas from gaseous Feedstock furnace, there would be no need to quench with quench oil and it can directly be quenched with water.

 

Hope a.m. explanations clarify about the point you are following to know...


Edited by fallah, 25 July 2022 - 05:51 AM.


#10 CHEMSTRONG

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Posted 25 July 2022 - 08:22 AM

Hi Fallah,

 

Thanks for your prompt reply.

 

My opinion is little bit different, let me know if you agree with me :

 

1) Liquid feedstocks Crackers produce high amount of Fuel Oil as part of cracked Gas exit Furnace unlike Gas Crackers. Liquid crackers have higher heavy HCs in their feedstock so when these HCs get cracked, they produce higher amount of Fuel Oil which is necessarily C9 + only. Quench oil is not imported stream for Ethylene Cracker but it is produced internally in plant. So they use this to reduce some heat from Cracked Gas.

2) For Gas Crackers, Quench Oil is not available so they only use Quench Water here.

 

Let me know if my understanding is correct here.

 

Best Regards,

CHEMSTRONG 



#11 fallah

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Posted 25 July 2022 - 11:25 AM

 

My opinion is little bit different, let me know if you agree with me :

 

1) Liquid feedstocks Crackers produce high amount of Fuel Oil as part of cracked Gas exit Furnace unlike Gas Crackers. Liquid crackers have higher heavy HCs in their feedstock so when these HCs get cracked, they produce higher amount of Fuel Oil which is necessarily C9 + only. Quench oil is not imported stream for Ethylene Cracker but it is produced internally in plant. So they use this to reduce some heat from Cracked Gas.

2) For Gas Crackers, Quench Oil is not available so they only use Quench Water here.

 

Let me know if my understanding is correct here.

 

 

Hi,

 

You didn't focus on my explanations:

 

For gas crackers quench oil isn't being used because the cracked gas can be cooled enough through the TLEs, not because the quench oil isn't available as by product of gas cracking...hence quench by water is adequate...

 

For liquid crackers because the cracked gas cannot be cooled well enough (risk of droplet condensation followed by coke formation) through the TLEs, at first it has to be quenched by quench oil and then by water...



#12 CHEMSTRONG

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Posted 26 July 2022 - 07:14 AM

Hi Fallah,

 

Liquid feed crackers TLE outlet will not be much different from that of Gas feed TLEs outlet as per my work ex. 

Let me know your thoughts.



#13 fallah

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Posted 26 July 2022 - 07:23 AM

Hi Fallah,

 

Liquid feed crackers TLE outlet will not be much different from that of Gas feed TLEs outlet as per my work ex. 

Let me know your thoughts.

 

Hi,

 

In liquid crackers, for potential risk of coke formation due to droplet condensation, the TLEs outlet temperature cannot be brought lower than, say, 300 C while in gas crackers such temperature can be well lowered due to lack of the mentioned potential risk.



#14 Joan Pinol

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Posted 27 September 2022 - 08:00 AM

Hello everyone,

 

We are trying to design a quench tower. The purpose of these quench is to cool down hot flue gas from 1100ºC (coming from a oxidizer) by adding some water in countercurrent flow down to 80ºC. Then, downstream it will be installed a scrubber for acid gases. 

 

I have searched some correlation but I have not found anything. Does anyone know where to size a quench column, direct cooling, without any packing bed?

 

Thank you in advance



#15 breizh

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Posted 27 September 2022 - 10:35 PM

Hi,

Consider Perry's chemical engineer's handbook to support your work. 

Note: A contactor liquid- gas without packing is not very common, spray nozzles technology could be an option.

BTW, did you check using your favorite search engine? 

Let you perform mass and heat transfer balances. A simulator should be the option for this task.

Good luck

Breizh 






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