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Snippets from commissioning: Plant's first breath of Hydrocarbon


Starting your own process plant is a dream come true.
So many people work countless number of hours to plan, procure, construct, understand process, ensure safety and  take care of every minute detail. Its like creating a new world which for many years in future will breathe, thrive and give employment to generations of people.
Five years later after the first kick off meeting with our technology licensors finally the day came when we were ready to take Ethylene in pipelines inside our plant's boundary area or battery limit (ISBL).
All we had to do was reverse one of the spectacle blinds and open isolation valves at upstream of spectacle blind.
But, Mr Murphy's laws killed the fun.
As we were opening bolts of blind's flange, we heard our gas meters screaming. Both the valves at upstream of this spectacle blind were passing.

We made a plan,
Let's connect few hoses and vent the pressure to flare. When pressure comes down we will open the flange bolts and reverse the blind. We connected all hoses we could but pressure decreased only marginally.
Soon the ideas came pouring in to decrease the pressure further and
as it always happens in brain storming sessions, people came up with bizarre ideas.
One person suggested, let's vent it to a bigger vent pipe which further vents it to a flare header. other suggested that lets bypass the knock out drum and directly connect the vent to bigger flare line going to flares. 
Thank God, we didn't proceed with these ideas.

The reasons for Why I say this is that:
In first case:
Pressure is cause and flow rate is an effect. Pressure gradient makes the fluid flow, flow rate is a result of Pressure gradient and not visa versa .  The flow rate will increase in bigger vent pipe but pressure drop will be same like in smaller vent pipe venting to a similar flare header.
In second case, you always collect your liquid material  in a knock out drum. Otherwise liquid if doesn't vaporize in flare, it will spew out at utterly high temperatures and fall as a hot rain burning vicinity. The liquids may also cause irregular combustion or may even extinguish flare flame

So after resting all our temptations we thought for a night and then eventually isolated valves in our tank farm in line at upstream of our ISBL and proceeded with our ethylene intake plan to comission our plant.

Safely to startup.



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