Dry gas seal in syn gas compressor 2

[mthakur]

Deal all, we have a problem of dry gas seal failure in syn gas compressor which operates at 160 KG dischrage pressure. For start up condition, to avoid contaminated gas flow from inside the machine to outside, sealing system provide a booser compresor which supplier high pressure N2 gas to provide the requried differential. In our case the booster N2 compressor doesnt seem to be performing well. Can you share your experience with booster compressor? Is this device installed in all the dry gas selas of high pressure compressors? Is there any other system which can replace booster.
regards

 

[flexibox]

Boosters are not installed in all gas seal instalations. They are normally required when clean gas cannot be guaranteed during start-up, shut-down or settle out conditions alternatively N2 bottles are used in place but you need to ensure there is sufficient N2 left after use for next time it is required. This ensure clean nitrogen is delivered to the seals at all times if boosters are not installed. The booster should not run for very long periods and if they do then you may experience seal problems within the booster. You should perhaps have a counter on the unit to know how many cycles the booster has run so you can prepare for maintenance.

 

[mthakur]

thanks for the reply, in our case even with boosters running, pressure differential across the seal faces to ensure clean gas flow is not being maintained. Could this be due to reduced capacity of booster which can not be measured or the increased lay seal just after the gas seal?

 

[flexibox]

It can be a number of things, internal Labyrinth worn (have you ever checked this). you need to maintain a minimum veleocity across the labyrinth, Booster seals damaged, booster selection incorrect. is the booster designed to cut in Automatically, if so where does it take signal to start & stop? ideally take differential pressure across internal labyrinth to guarantee clean flow at all times. Do you have heater in panel? is there liquids in gas causing problems with booster? Check your filters for moisture and are they coalescing filters with a sufficient element size?
It sounds like you need to review the whole gas panel design and you may find that with some modifications you will sort this out but get the experts involved. There are many poorly designed gas panels which are the root cause of Gas seal failures.

 

[mthakur]

HI there, damage to the internal seal was checked and found OK during the last replacement. boosters are designed to cut in and off as per the requirement for rstart ready. diffential can be measured between casing pressure and booster discharge, as per design requirement same has to be 5 bar for ready start condition which we are not able to achieve and are forced to roll the machine as it is.

The panel is fitted with steam heating coil but its tuned off due the good gas quality with no possibility of having moisture, I like your suggestion of reviwing the whole design. what is the best approach to go, consult the seal vendor or the compressor supplier in such cases?

 

[flexibox]

I believe that you are better speaking to a seal vendor who specialise in building these systems. they understand seal leakage rates, minimum velocity requirements across labyrinth, heating requirements, filtration size and latest in booster design. good luck