How to measure pH of a Gas
How to measure pH of a Gas
(OP)
I am currently in the process of trying to find a good way to measure the pH of a gas stream and I am searching for alternatives.
The application is in an oil refinery, the gas stream is the flare header gas, made up of a variety of hydrocarbons, basically anything and everything in the refinery depending on what is happening in the various units.
The idea that we are going with right now is to draw the gas through a liquid (water) and measure the pH as a result. However, I have been unable to find anyone in the industry who has done this sort of thing before, I have checked with local lab techs, engineers, vendors, etc.
Our process engineer seems to think that this is going to work without a problem however I am not so sure.
Any information hints or history would be appreciated.





RE: How to measure pH of a Gas
So, the REAL question is what question are you actually trying to answer by this measurement?
TTFN
RE: How to measure pH of a Gas
RE: How to measure pH of a Gas
RE: How to measure pH of a Gas
RE: How to measure pH of a Gas
Go ahead and ask the question, "SHOULD THE HEADER BE MADE OF CORROSION RESISTANT MATERIAL, OR CAN WE ACCURATELY PREDICT WHEN THE CS PIPING WILL FAIL".
RE: How to measure pH of a Gas
Additionally, have you actually determine how MUCH gas is required to get a positively unambiguous pH reading?
Generally, you'd need a sizable fraction of a molar to get a meaningful result.
TTFN
RE: How to measure pH of a Gas
Anyway, all of the gas in the flare header is sent to a flare gas compressor which pushes the gas back to an amine unit where it is cleaned and turns into fuel gas to be burned in boilers / furnaces throughout the refinery. The flare gas compressor runs roughly 75% of the time when the conditions are right, i.e. sufficient mole weight and volume.
The idea of the pH analyzer is to give the board operator an automated indication of the acidity of the gas going to his compressor. We have had an instance where we were compressing acidic gas for some time with out knowing it until one of the sight glasses on the compressor sprung a leak, obviously very costly rebuild.
Appreciate all the feedback!! Keep it coming!!
RE: How to measure pH of a Gas
RE: How to measure pH of a Gas
TTFN
RE: How to measure pH of a Gas
RE: How to measure pH of a Gas
TTFN
RE: How to measure pH of a Gas
I'll let you know how I make out.
Thanks!!
RE: How to measure pH of a Gas
I would like to point out that I don't work for Siemens, lol! Therefore have no vested interest, just a customer of theirs.
RE: How to measure pH of a Gas
ABB Extrel
Hamilton Sundstrand AIT MGA iScan.
Siemens Quantra
Thermo Onix VG Prima ?B
Ametek
Monitor Instruments
RE: How to measure pH of a Gas
Otherwise do a complete on-line process stream monitoring, continuous or on a sampling basis.
RE: How to measure pH of a Gas
RE: How to measure pH of a Gas
The cost is pretty much what drove us this way, budgetary quote came back at between 7 and 10 K for the hardware, this is about 1/3 the cost of the cheapest analyzer that we looked at.
Anyway, I'll try to write back in a few months and let you know how it worked out, thanks for all the feedback.
RE: How to measure pH of a Gas