MORE FUEL GAS ABSORBTION IN MDEA FOR GAS SWEETENING PROCESS.

[RAMAKOTAIAH]

HELLO,

OURS IS GAS SWEETENING PLANT DESIGNED FOR REMOVAL OF H2S BY USING MDEA AS SOLVENT. IT IS DESIGNED FOR 1375 PPM OF H2S BUT AT PRESENT FEED IS HAVING 150 TO 180 PPM. DUE TO THIS WE HAVE REDUCED SOLVENT RATE TO 175 M3/HR FROM DESIGNED 228 M3/HR AT 50% BY WEIGHT SOLVENT CONCENTRATION.

AT PRESENT WE ARE FACING THE PROBLEM MORE HC ABSOBRTION IN MDEA, THAT IS GENERATING MORE THAN DESIGNED FLASH GAS IN THE INTERMEDIATE MP FLASH SYSTEM PROVIDED BEFORE LP REGENERATION SYSTEM. THIS IS EFFECTING FEED RATE AND QUALITY OF PRODUCT. PLEASE HELP ME BY ANSWERING FOLLWONG QUERIES:
1.) FACTORS EFFECTING HC ABSORBTION IN MDEA.
2.) HOW TO CONTROL IT.

RAMA

[eugenedakin]

Hi Ramakotaiah,

First Question: Factors effecting absorbtion of flash gas
a) lower the pressure differential between the MDEA and gas
b) lower the concentration of flash gas available (separation upstream?)
c) lower the contact time of MDEA with flash gas

Second Question: How to control it
a) install a separator upstream
b) carbon filters (expensive)
c) install larger gas flash drum
d) lower throughput rate of MDEA (you will need to increase MDEA concentration to compensate for H2S removal)
e) install a larger knockout
f) ensure knockout is working

I hope this helps,

Eugene