In some paper, the authors used the mix gas, like 10 ppm H2S/1bar CO2, i am very surprised the amount of H2S can be controlled so accuratly. I have no idea how to control the amount of H2S reach the ppm level, can somebody tell me ? Should i by some equipment?
In some areas it is possible to purchase pre-mixed CO2/H2S in gas cylinders with desired H2S concentrations, However, when talking about low ppm levels, the requested H2S concentration in the gas may only exist at the suppliers facilities as the gas is being mixed. In the time between being mixed and eventual use, the gas will slowly react with the steel cylinder. This will result in slow drop in the H2S level. How fast this occurs will depend on if the cylinder has seen past H2S service and the storage temperature and transportation temperature.
Therefore, to know the H2S concentration of the gas, you really need to run a GC analysis at the same time as your test. If you don't do this, instead of haviang 10ppm, the level could be something lower. I have seen CO2/200ppm H2S gas drop from 200 a the time of delivery to around 120ppm a month or two later.
That is one of the reasons why I used a continuously metered stream of CO2, Na2S and dilute HCl and brine when I conducted my low H2S autoclave testing. We then did periodic dissolved H2S analyses of the fluid flowing out of the autoclave. This is the only way that we could figure out to be certain of the exact H2S levels that we were using in my tests.
In some areas it is possible to purchase pre-mixed CO2/H2S in gas cylinders with desired H2S concentrations, However, when talking about low ppm levels, the requested H2S concentration in the gas may only exist at the suppliers facilities as the gas is being mixed. In the time between being mixed and eventual use, the gas will slowly react with the steel cylinder. This will result in slow drop in the H2S level. How fast this occurs will depend on if the cylinder has seen past H2S service and the storage temperature and transportation temperature.
Therefore, to know the H2S concentration of the gas, you really need to run a GC analysis at the same time as your test. If you don't do this, instead of haviang 10ppm, the level could be something lower. I have seen CO2/200ppm H2S gas drop from 200 a the time of delivery to around 120ppm a month or two later.
That is one of the reasons why I used a continuously metered stream of CO2, Na2S and dilute HCl and brine when I conducted my low H2S autoclave testing. We then did periodic dissolved H2S analyses of the fluid flowing out of the autoclave. This is the only way that we could figure out to be certain of the exact H2S levels that we were using in my tests.
Thank you for your help! Mr. Stephen N Smith and Mr. Wojciech JERZAK.
In China, we can purchase the pre-mixed CO2/H2S, i will try to do some tests in the CO2/ 200 ppm H2S solution. Thank you for your help.
how i can calculate 1 ppm of H2S from 0.1m/l Na2S in volume?
Dear Pengpeng Bai
First of all you need to know the pressure and temperature of your system . Then you need to calculate the number of moles of each gas in the gas mixture and determine the over all weight of the gas mixture. out of this you can determine the weight of 1 ppm of H2S , convert that to number of moles, then to partial pressure .
Dear Wadah Jawich
I have 500ml of Na2S in concentration of 0.1m/l in a desiccator and I should take 1ppm of H2S from it by syringebut I need to know how to calculate 1 ppm of H2S from this solution so if you have an idea please let me know how I can do
it is not a straight forward calculation, where do you want you 1ppm of H2S ? in the solution or in the gas phase?
dear Wadah Jawich in a solution I used a solution of Na2S to evaporate H2S then I take the generated gas by syringe and inject in a box with samples so I need to calculate the amount of H2S inside the box
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