2 replies to this topic

[skhattak]

Dear All,

I am working in oil and gas plant and we are facing much problems in condensate stabilization. Our condenstae separation and stabilization process is described below.
Condensate from high pressure separator is routed to MP separator, where after necessary separation of condensate, it enters into plate type heat exchanger and exchanges heat from hot condensate coming from condensate heater. Estimated total duty of exchanger is 1.2 MMBtu/hr.

Condensate discharged from MP Separator is preheated to around 105 Deg F in a plate type Condensate/Condensate Exchanger, the pre-heated condensate is further heated in Condensate Heater to a temperature of around 120-130 deg F, while heater bath temperature is maintained at 180-190 Deg F. Duty of condensate heater is 2 MMBtu/hr.
Hot condensate is then diverted to Degasser where entrained gas flashes off and condensate is further stabilized.Hot Condensate is passed through the Condensate/Condensate Exchanger and then sent to storage tanks. Further to this NGL extracted from raw gas in LTS (Low temperture separator) from De-ethanizer is also transferred to the discharge of MP separator. Which is basically the main reason for higher RVP.

Actually the facility was designed for crude but due to some necessary changes in production formation, the same facility is being used for condensate also.
Our Bottlenecks in controlling the RVP are.

Flash gas compressor which is running at full load and having a capacity of 1 MMSCFD. Flash gas compressor is used for compressing flash gases from MP separator, Degasser and De-ethanizer.

Condensate heater which is also running at its full duty.

Low temperature from well

Degasser is insatlled instead of proper stabilizer

specification of degasser are.

Diameter = 75 inches, Length = 13 feet
Design Pressure = 50 Psig at 200 Deg F
My question is how to lower the RVP upto 7 psia in the existing setup, whereas current RVP value is above 11 psia. Kindly guide regarding the same.
If we want to install proper stabilizer additionaly in the existing setup, then what will be the re-dsign criteria and specification of stabilizer. I am attaching herewith the layout for condensate cycle, if anyone can modify with the specification. Our current condensate production rate is 1500 bbl/day and would be increased upto 7500 bbl/day in near future.  Condensate cycle.bmp   1.45MB   21 downloads

[ankur2061]

skhattak,

You have provided a very generalized description without providing any sketch or diagram of your system. The only advise I can provide is in the form of a reference book which deals with the basics of condensate stabilization and some operational schemes and their description for condensate stabilization to reduce RVP.

Reference:

Chapter 6, Condensate Stabilization, "Surface Production Operations- Volume 2" by Ken Arnold & Maurice Stewart

This is one of the most exhaustive description I have personally come across for condensate stabilization.

Regards,
Ankur.

[aransari85]

Hi,

As i understand, the existing unit is designed for crude unit but you are using it for De-ethanizer bottom stream also. Due to which lighters in the condensate is increasing and inturn increasing RVP of condensate.

Existing system is sigle stage saperation where you are removing lighters by heating it to 125 F and then flashing it in the degasser and bath temperature is 180 to 190 F.

you might be maintaining some pressure in the degaseer at which you are getting some separation and you are getting RVP as 11psia. I suggest you can try increasing the condensate heater outlet temperaute by 20-30F, if this is possible in the condensate heater which will saperate shift the equillibrium of condensate to some higher RVP. You can try to simulate the process in any simulator and check exact temperatures.

One disadvantage is that, there is no absorption stage provided in the existing set up which will lose some heaviers in to off gas which will increase the load of off gas compressor.. you can know from the simulation results how much you can increase upto..

If you provide PFD of the unit, someone can work on it.

For the new unit at 7500bpd, i suggest you provide a stabilizer column.

Regards,
ARA