6 replies to this topic

[cruam]

Dear all

I have some question about Amine plant for co2 recovery from flue gas:

as shown in the attached file, there are a washing water cooler for absorber and a reclaimer in a conventional amine plant.

in my simulation I consider a washing section inculed 3- 4 tray top of the absorber. at first I had just added a fresh water stream to the top tray (tray1) as a wash water without cooler and recycle to column. but I saw in amine plants a washing cooler should be included. when I did so, the amount of MEA loss in the overhead stream increased and I had to increase amount of make up water. Acoordingly, the question is that what is the basic reason to have a wash water cooler in spite of that it doese not have significant effect on wash water consumption??

the second one is about reclaimer,

I've red that heating and adding some water and soda ash to a reclaimer should be continued to reach the same MEA composition in the outlet vapor of the reclaimer as in the lean MEA fed to it and this temperature should not exceed 148 C for MEA (Gas Purification) is it correct in practice??

the other question is about Amine loss because of heat stable salts formation. How can I calculate or find the amount of HSS at the operation condition applied in my case? I've found some data for amine losses due to vaporazation or average amine loss in the plant (1.6 Kg/tonne CO2)but not especific about HSS!!


the final question:

in co2 recovery plants a soda ash tower and a [b]Potasium permangenate column is necessary. I can not find any specific information about them to calculate the amount of Soda ash or KMno4 needed in my case. is there any guidline for it?

Thank you all

Regards,
Cruam

Attached Files

•  pilot plant.pdf   71.86KB   46 downloads

Edited by cruam, 04 May 2010 - 01:05 AM.

[Art Montemayor]

Cruam:

Please tell us exactly what it is that you are doing – or trying to do. Are you designing a CO2 “capture” process? Or are you analyzing such a process? Why are you attempting to simulate what is already designed?

Are you experienced in applying a CO2 removal system? Are you knowledgeable in dealing with amine CO2 removal processes? What is the purpose of your questions? The reason I ask all these questions is because I have designed, built, installed, modified, and operated many CO2 removal, storage, transport, and conversion plants and I don’t want to confuse you with what I consider basic facts and knowledge. I also don’t want to waste a lot of time on subject matter that is already understood.

You basically ask four (4) questions:

1) What is the basic reason for having a wash water cooler when it does not have significant effect on wash water consumption??
The answer is: You are obviously not doing your “simulation” correctly, or you don’t know how to apply the principle. A water wash works. And it works better when the water is cooler than the exiting gas (mostly nitrogen).

2) It is not only correct practice to use an MEA reclaimer still, but it is essentially a strict requirement in order to maintain a stable, clean, and essentially pure MEA circulating solution. You fail to state what is your basic data – such as MEA solution concentration, flow rates, pressures, etc.

3) How can I calculate or find the amount of HSS at the operation condition applied in my case?
The answer is: You can’t. HSS formation is empirical data and you can only predict it after you operate the specific process and equipment. Don’t waste your time trying to calculate something that uncalculable.

4) Is there any guideline for a soda ash tower and a Potassium permanganate column being applied in the CO2 removal from flue gas?
The answer is: Yes, both are recommended – but their recommendation depends on the type and quality of flue gas being treated. You have failed to furnish any basic data on the flue gas, so no comments can be generated. Basically, the Soda Ash tower is used prior to the flue gas entering the amine absorber. The permanganate treatment is applied usually after the first stage of CO2 compression.

[cruam]

Dear Art Montemayor

Thank you so much for your reply. I'm working on the simulation of a CO2 capture process from a low pressure flue gas containing approximately 12% H2O, 12% CO2, 0.08% SO2 and 0.03% NOx and 74% N2 and 1.5% O2 (in mole percent). surely I'm not experienced as much as you in CO2 removal/recovery plants and I'll be so thankfull if you guide me.I'm working on this simulation by the use of Promax as the first step of a plant design.

About wash water: as I found this section is necessary to eliminate or decrease amine losses through vaporization from top of the absorber, I asked that question. I know this cooling has benefits on tower operation but I don't know if this cooling and recycling should decrese the fresh water consumption or not? as in my case it isn't so.

for reclaimer:
inlet lean amine fed to the reclaimer (3% of total circalation rate)at 122C, 2 bar and 10gpm contains approximately 21% MEA, 78% H2O and 2% CO2 ( in mass percent). lean load=0.14 and rich load=0.38, rich approach=76% and lean approach=27%. the MEA solution concentration =20%wt. now , Is it correct that the MEA composition in the outlet vapor of the reclaimer should be as same as in the lean MEA fed to it and reclaimer temperature should not exceed 148 C for MEA?

for Soda ash :
inlet gas condition: flue gas stream with 5000 CFM flow rate and composition as same as mentioned above at 140 C and 1.7-1.8 bar.
the target value for SO2 in outlet gas is <10 ppm.

If it is needed I can give further data.

Edited by Art Montemayor, 04 May 2010 - 07:11 AM.

[research papers]

Could I please know what simulation softwares can be used in order to calculate amine loss from the absorber?

[Art Montemayor]

Research:

I don't know of any software to calculate an amine water wash unit operation.

I have resorted to empirical methods in the past, increasing the water wash as I could notice that more amine was being captured and recovered economically.

[research papers]

Thank you so much Art. Thanks for your prompt reply

By any chance is it possible for you to explain the design of water wash,how it works with the operating conditions?

I am working on calculating amine loss using excel.It turns out to be highly tedious with a lot of calculation involved. I was wondering if the loss could be calculated by just using the difference of amine in the vapor phase from the absorber to the amine from the water wash or should I also have to consider the liquid/gas flow rate?

[research papers]

Sorry I kinda muddled up the question.

The difference between the amine from the absorber to amine from the water wash would give the MEA recovered in the system. How do we calculate the amine loss from the water wash?