8 replies to this topic

[Ra v]

Hi,

 

I want to calculate the rate of condensate producing in gas cooler downstream of stripper.

 

 

Rgs

A Ravi

Attached Files

•  VLS.xlsx   15.93KB   62 downloads

[shan]

Nobody is able to tell you the condensate rate without operating pressure values and stream compositions.

[kkala]

I would agree with shan. Heat balance can be the first step to specify heat supplied to cooling water (28-34 oC). Same heat is removed form gas (98-32 oC), which will eventually reach dew point at conditions, then start being condensed. Knowing flow rates, as well as gas  pressure(s) upstream of control valve, will be sufficient to estimate gas enthalpy there; temperatures are already given. Scheme in "VLS.xlsx" is clear, but the spreadsheet has to be completed with conditions, even better with calculations too. In this way generic answers as this one could be avoided.

[Ra v]

Kkala and Shan,

 

Please find the rev excel sheet.

 

Rgs

A Ravi

Attached Files

•  VLSRev.1.xlsx   16.49KB   69 downloads

Edited by Alamuri Ravi, 01 March 2013 - 04:09 AM.

[kkala]

Now we can estimate heat exchanged, based on cooling water side: Q=60*60 kg/h x 1 kcal/kg/oC x (34-28) oC = 21600 kcal/h (25.1 kW).

But something important: Critical temperature of pure CO2 is ~31 oC, <http://encyclopedia....ia.asp?GasID=26>. Above this temperature, CO2 cannot be liquid irrespectively of pressure.

It is also noted that saturation pressure of pure CO2 at (say) 30 oC is ~73 kg/cm2 a. For constant temperature of 30 oC, gaseous CO2  will contain no liquid CO2 below this pressure.

Consequently there will be no CO2 condensate under presented operating conditions (1.2 kg/cm2 absolute or gauge?). Probably you need to revise data? Is it pure CO2, or a mixture?

Edited by kkala, 01 March 2013 - 06:08 AM.

[Ra v]

Kkala,

 

It is the Gauge Pr and its not a pure CO2.

 

Its a CO2 production by diesel  with MEA absorption (15 % Conc), So from the stripping unit the gas comes out with a temp of 92 Deg C and It enters in CO2 Gas cooler where it is cooled to a temp of 32 Deg C and then Vapor liquid seperator where the condensate is collected and sent to absorber. The impure CO2 gas then goes to KmnO4 tower to remove impuitires and thereby it is again compressed and sent to liquification unit.

 

Rgs
A Ravi

[shan]

The condesate flow is 13.7 Kg/hr if we assume the inlet is CO2 saturated with H2O (CO2 57.14 mol%, H2O 42.86 mol%).

[Art Montemayor]

A Ravi:
AsI have already stated and showed you numerous times on our Forums, you are forcing our members to “jump through hoops” and spend their efforts and attempts to help you in vain because you don’t tell ALL THE TRUTH about your query.

 

The total truth is:

You are operating a nominal 100 kg/hr CO₂ combustion generation plant using MEA in a direct-fired reboiler instead of generating the Combustion in a standard steam boiler.  This is a cheap, low-budget type of design that generates an excess amount of steam vapor over that required to strip the CO₂.  The excess steam vapor is OK, as long as you have sufficient stripper and cooler-condenser capacity.

By not stating the above, our members are going all over the place in making the wrong assumptions, trying to help you.  They don’t know that the vapor going to the cooler-condenser contains well in excess of the amount needed to saturate the CO₂.  But I do, because I have designed, built, installed, and operated more than one of these type of plants.
 

You also fail to tell them that you are insisting on using a timer-switch on a solenoid or similar valve to drain the vapor-liquid separator – something I already warned you about NOT doing because it is the wrong way to positively control the correct drainage of the produced condensate.  I have even sent you pictures and identification of what to buy and install – including the size that should do the job.

I will repeat my advice one, last time: you are doing the wrong thing.  All you need is a low-cost, 1” float drainer (as made by Armstrong and many others) and this will work well and for many years.  A better method would be to install a level detector/controller with a control valve – like a Fisher level-trol.  But since you are hard put for operational funds and maintenance, you can get by with a float drainer.  It is as simple and easy as that.  You are making a mountain out of a mole hill.  I am attaching your workbook as Rev2 wih my comments.

 VLSRev.2.xlsx   18.36KB   65 downloads

[Ra v]

Thanks for your advise Art.

 

I will install a float drainer at the vapor liquid seperator.

 

Rgs

A Ravi