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[Flyou]

Hi there!
I am a process engineer working in the field of petroleum industry since 9 years.
I have a problem concerning the dissolution of a gas in a liquid stream for start up purpose.
The scheme is the following in normal operation: a liquid stream is coming from BL and enters a drum blanketed with a pressure control. This liquid is then sent to a high pressure system with a centrifugal HP pump at the bottom of the vessel.
During start up, the aim is to dissolve a gas in this liquid stream before sending it to the HP system so we have foreseen an injection of gas upstream the drum with a minimum distance of 20 diameters.

Let's say for example that the gas solubility at operating P&T conditions is 1000 ppm and that we need at least 800 ppm in our stream to ensure a good start up.
When we talk about solubility, it means that an equilibrium is reached between the 2 phases L&V and to ensure this equilibrium as quick as possible, we need to facilitate the material transfer between L&V. This could be achieved by maximizing the turbulence and the surface area between L&V ie to have very small bubbles of gas dispersed in the liquid. For me, if a simple injection of the gas is considered (pipe in a pipe) no matter the min distance of 20 diameters, without any special device (sparger or else) then the risk is not to reach the equilibrium of solubility and to be far from it... The result would be a small dissolution of the gas compared to solubility and the quantity of gas injected and not dissolved would be sent to the flare by the PC control of the drum... Another thing that could help to increase the solubility of the gas I think is to reduce the temperature of the liquid stream.
Another solution I was thinking about is to inject the gas at the bottom of the drum, directly upstream the centrifugal pump but cavitation could appear... Nevertheless I think that a centrifugal pump can accept a small quantity of gas at its inlet (how much in %vol?).
The last solution I was thinking about which is the most expensive is to consider a metering HP pump to send the gas (in a liquid form) to the HP system.

Does anybody has already face this kind of issues in a unit? What would be his advice to help? Are there any device sellers that could guarantee a % of dissolution compared to solubility?
Thx for yr help!
Flyou