Frequently Asked Quesitions
How does 15-30 mol% CO2 effect 10-40 ppm H2S removal rates and efficiencies?
Due to their molecular structure, Tetra 300 and Tetra 412 are not prone to absorbing CO2, and does not appreciably affect the ratio required to react with H2S. However, under certain partial pressures and conditions CO2 could form carbonic acid which could impair the ability for Tetra 300 or Tetra 412 to react with the H2S, but probably only slightly.
Is there any non-reacted formaldehyde in your products at any levels?
No. Both products being introduced here (Tetra 300 and Tetra 412) have no non-reacted formaldehyde. During our reaction process all formaldehyde is reacted. We have had lab tests ran and they show we have excess ethanolamine in the end product, therefore we know that all formaldehyde has been reacted.
What level of activity are your products? 50%, 100%?
We blend the products back as per the customers request.
Do you have a concentrated version?
Yes. We have Tetra 412 (59 % Active) and we have Tetra 300 (89 % Active). The Tetra 300 should be blended down 1/3 with methanol and RO water. If you are not using RO water then the water must be chelated.
When you quote activity what does it measure, active ingredients?
When we quote activity it is based on active ingredients.
Is your active component triazine? Is there anything else?
Yes, you are correct in assuming that the triazine is the primary ingredient that scavenges the H2S, however the other ingredients play a key role.
What are your efficencies in total standard cubic feet of H2S removed per gallon of 50 wt% scavenger for both pipeline and tower treating applications?
We recommend using 30-33% wt% of scavenger.
What are your velocity and residence times needed for injection and tower treating applications to be successful?
When 80% of triazine is consumed, you tend to precipitate out the by-product dithiazine.
What is the reaction by-product of H2S with triazine and will it cause plugging down-hole or foaming in a downstream TEG dehydration unit?
The reaction by-product of H2S with triazine, is a sulfanated amine which will act as a mild corrosion inhibitor that is water soluble. It will not cause plugging down-hole or foaming in a downstream TEG dehydration unit. We do not use any inorganic bases in our H2S scavenger. Plugging is possible when inorganic bases such as sodium hydroxide are used in the scavenger. It makes sodium sulfide which is a solid and not soluble in water.
What effect does water in gas have on the efficiencies and what guidelines do you have?
This is a three part answer. First, if you have wet gas then it has no affect on the scavenging process. Second, if you have dry gas, it can cause evaporation of the water from the scavenger. You can remedy this by adding water. Be careful though if you are using produced water because it could cause some scaling. Third, if the gas has free water then it can dilute the scavenger.
How do you determine the correct concentration for a tower and pipeline treating process?
As a rule of thumb (.03 to .09 ) x ppm H2S x mmcfpd would be used to determine the correct concentration for a pipeline and .11 x ppm H2S x mmcfpd is used to determine the approximate concentration for a tower.
In a tower application is it better to inject upstream of the tower?
Yes, then the tower can be used to polish the gas.
What is the formula/calculation to purge a given volume of scavenger out of a tower and recharge to keep from fouling the vessel? If any?
As a general rule, when more than 80% of the triazine is consumed you tend to precipitate out the by product (dithiazine). Therefore in a tower application one would like to recharge the tower when it gets to the 80% mark. In normal towers this is not an issue because you tend to get H2S breakthrough once you exceed the 80% number. Where it is extremely important is for flooded towers or circulating contactors. In both of these cases you are essentially recycling the scavenger so that one could achieve 100% consumption of the triazine. If that occurs you will also be precipitating dithiazines and having plugging problems. In these cases you must calculate the theoretical amount of scavenger using an 80% number for the efficiency.
What is the residual powder substance left behind when you empty a vessel? How sensitive is it to water or lack of water?
The residual powder substance left behind when you empty a vessel is Dithiazine. It is water soluble/dispersible. Normally it is in the water and not seen. The quantity is very minute if consumption of triazine is 80% or less. If sodium hydroxide or any other inorganic base is added in order to increase efficiency then you will get other residual substances that are not soluble in water and could cause plugging. Tetraco, L.L.C. does not add any inorganic bases in our scavengers. Our scavengers are very efficient without adding any inorganic bases. Scaling is another possibility.