2 replies to this topic

[muddu4]

1. At Existing refinery, flare gas from various locations is collected in flare KOD followed by water seal drum before disposing it through flares stack, In order to recover these flare gases & to incorporate zero flaring philosophy, Flare Gas Vapor recovery package was proposed,

Under Current scenario, Tie-in for VRU was taken upstream of water seal-drum. Now the water seal drum being located at long distance approx. (100m) from tie-in point, the line to water seal drum is undergoing stagnant corrosion since no gas flow. Further as flare not being operated chances of air ingress through burners are quite high and air accumulation in vapor space of water seal drum could lead to explosive mixture (Less Hydrocarbon and more of Oxygen).

If the Suction pressure of compressor is lower than water seal drum than gases will pass thru water seal drum & if higher than no gas to seal drum leading to corrosion problem.

 

How can these operational problems can be overcome?

 

2. Is it necessary to reduce/throttle purge gas (Fuel gas) on flare header since we are reducing flaring or should it be kept under full open condition?

As per my understanding since we already have water seal drum downstream of flare KOD to maintain positive pressure so why we need to keep purge gas fully open?

As per client during hot release as soon as gas enters flare header it gets cooled down and temperature shrinkage occurs. Hence it is better to keep purge gas always open instead of throttling.

 

Is there any guideline for flare header operation?

 

3. Under current design vendor have considered Liquid ring compressors for Vapor recovery package, however client have requested to do study about using   eductors as they serve better purpose as compared to liquid ring compressor due to large fluctuations in flowrates and compositions throughout entire day. With liquid ring compressor client have to continuously run by-pass line to overcome these fluctuations with lead to high power consumption.

 

Does anybody have experience using eductors instead of liquid ring compressors?

[Bobby Strain]

Sounds like you need help. Talk to John Zink, now a part of Koch companies.

 

Bobby

[shvet]

3. Under current design vendor have considered Liquid ring compressors for Vapor recovery package, however client have requested to do study about using   eductors as they serve better purpose as compared to liquid ring compressor due to large fluctuations in flowrates and compositions throughout entire day. With liquid ring compressor client have to continuously run by-pass line to overcome these fluctuations with lead to high power consumption.

 

In our plant we have:

- existing 8 piston reciprocal compressors 305ГП in parallel and water seal in suction. 1200 m3/h and 16 barg each. Manual start-stop.

- new 4 water-ring centrifugal compressors GARO AB 2500 in parallel and water seal in suction. 2500 m3/h and 6 barg each. Auto stop on suction pressure and manual start. Under construction yet.

All work well. No problems. We have no continuosly run bypass. For less power consumption we have compressors in parallel instead of 1 compressor.

 

 

 

Under Current scenario, Tie-in for VRU was taken upstream of water seal-drum. Now the water seal drum being located at long distance approx. (100m) from tie-in point, the line to water seal drum is undergoing stagnant corrosion since no gas flow.

200-300 m. We haven't met this problem yet.