In the gas plants, gas condensate often contains unwanted glycol, water and salt together with light HC, H2S, mercaptanes which are soluble in condensate and cause corrosion, fouling, plugging, scaling, catalyst poisoning and other detrimental effect on plant operation. Condensate stabilizing is a process that mainly uses for separation of mentioned components from raw gas condensate in order to meet product specifications which is on-spec RVP, water and salt contents for the ultimate product.

At the overall view point, condensate stabilizing process consist of four main parts which are; separation of free aqueous phase and light HC from heavy HC in a high pressure three phase separator, desalting and sludge removal using desalter, separation of remained light HC by a medium pressure distillation tower and finally degassing of column stabilized product plus with debutanizer bottom product (C5+) in a low pressure flash drum in order to produce final product for sending to atmospheric storage tanks.

As a real case in our gas plant, due to low performance of stabilizer reboiler, efficiency of process was reduced gradually and caused off-spec product to be produced. So, other operational parameters affect on process efficiency was changed and optimized in order to compensate product specification and meet on-spec values. The most operational parameters which affect product specifications are as below:

  1. Changing demulsifier and water wash injection to desalter mean while draining of interface layer of desalter once per each operating shift.

  2. Optimization differential pressure of the desalter mixing valve.

  3. Effect of stabilizing column pressure reduction to the optimum value, in a way that does not affect proper working of off-gas compressor.

  4. Effect of increasing stabilizer column condenser temperature.

  5. Effect of increasing temperature of inlet feed to stabilizer column.

  6. Effect of (C5+) flow rate and RVP on the condensate RVP.

This paper introduces main results of the actual case studies in plant together with simulation results. Comparison between actual and simulation results indicate excellent satisfaction from practical engineering standpoint and high reliability of test run.

Keywords:
Modeling & Simulation, gas processing, separation and treating, psia, desalter, gas plant, different operational parameter, condensate, operational parameter, bottom temperature
Subjects:
Processing Systems and Design, Separation and treating, Gas processing
Copyright 2009, Society of Petroleum Engineers
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