7 replies to this topic

[fapbo7]

when i run a 3 phase sep, with component list as N2, co2,h2s, c1,c2,c3,ic4,nc4,ic5,nc5,nc6,nc7 with 50 mmscfd feed sour gas coming to the sep., i met a question. first, i use a mixer to add a water stream to saturate the sour gas which contain the ic5 nc5,nc6,nc7 heavy HC components. when i connect the saturated stream to the 3 phase separator. There is no condensate coming out of the sep. only water coming out and a bit more than 50mmscfd gas from the vap. side. MY question why the ic5,nc5,nc6,nc7 those heavy HC not separate out of the stream. The outlet vap. is more than the feed gas stream, it's look like some water to flas out and go to vap secton. The 3-phase sep. is really not work out here. Pls help me out the question as i am new in hysys. many thanks

[Zauberberg]

Check if saturated stream (separator inlet) temperature and pressure are the same as initial fluid conditions (prior to water saturation). One common mistake I usually find is that water is added at much lower pressure and the resulting stream is, by default, at the lowest mixing pressure. I suppose you connected all 3 outlet streams to the separator vessel (look at the sketch below).

I don't know what is the amount of heavier hydrocarbons, but you should get some condensate flow. And check if you are using correct fluid package, PR or SRK are there for such systems.

[attachment=870:Water_Sat..xls]

[Root]

Hi,

Have you check the product stream, flow and compostion specs are given and you have used correct fluid property package used, 'PR,RK"
and also check pressure and temp condtion of sperator.

[fapbo7]

Thanks Zanberberg and Toor,
i still don't get the result. Actually, i do add a water to saturate the dry gas before entering to the 3 phase separater and the 3 phase sep. inlet stream is saturated already. Here is the conditions:
dry gas :Mol% N2 0.0025; CO2 0.0519; H2S 0.1073; c1 0.6792 c2 0.0874 c3 0.0416 ic4 0.0072 nc4 0.0119 ic5 0.0034 nc5 0.0032 nc6 0.0028 nc7 0.0016.
30 deg C & 300psia.
Dry gas : 50MMSCFD
I use above conditions to run the 3 phase separater, but still don't get the condensate from the sep. pls help me, thanks !

[Root]

Hi Fobpo7,

Relex the Temp and pressure of the separator, and then run the simulation and problem will solve.
Good luck

[Zauberberg]

I've checked your data, and with this composition at 30C and 20.68bar (300psia) there is no condensate flow from 3-phase separator. The amount of C5+ is very low (3.75% weight) and C1 partial pressure is very high.

Equilibrium content of water in the gas is 0.228% mole which is equal to approx 1740 mg/Sm3.

[fapbo7]

Thanks Zauberber &Toor,
Dear Zauberberg, actually, i dont follow your answer, and the approx 0.0301Mol% C5+ components in the 50MMSCFD feed gas is containing about 1.505MMSCFD C5+ content, which must have some condensate out of the main stream. and there is no reason for no Condensate separated in the 3 phase separater. this is my thought which might r=wrong and pls correct me if i am wrong. Also, i use PR pkg. The dry gas before entering to the separater is saturated regarding the field real condition because the real gas is full saturated stream. I know this is a very simple single unit in the HYSYS but i stuck to this and I really want to solve it to improve my simulation skills in the HYSYS. Thanks fpr any reply.

[Zauberberg]

Fabpo, there is no condensate at process conditions you specified. Partial pressure of C1 and noncondensables is very high, causing heavier components to be carried away into the vapor stream. You cen check this yourself, simply by plotting phase envelope and looking for cricondenbar and cricondentherm values. As you are probably aware, above certain values of these parameters - which are a function of composition - there's no possibility for two phases to exist together.

Best regards,