A technique has been developed to allow for the comparison of scavenging rates and scavenging capacity of different hydrogen sulphide scavengers by continuously measuring the hydrogen sulphide concentration in the gas phase of a multiphase system. In addition, the stability of the scavenger reaction products has also been investigated.
The methodology to assess the performance of the hydrogen sulphide scavenger is described. The scavenging rates of the hydrogen sulphide scavenger are compared by the contact time required to reduce the initial hydrogen sulphide concentration to a pre-determined value. In addition, the scavenging capacity of the scavengers can be calculated by recording the gaseous hydrogen sulphide concentration once the reaction has been allowed to run to completion. Finally, the stability of the scavengers and their reaction products, including carbon disulphide, are determined by treating a solution of the scavenger with excess hydrogen sulphide.
It is known that hydrogen sulphide scavengers have the potential to form reaction products that can foul the refining process. More recently, it has been identified that carbon disulphide may be produced during the scavenging reaction of some commonly used triazine based chemistries, driving a desire to identify alternative products. These works describe a new method which is capable of differentiating between the hydrogen sulfide scavenging performance of different chemistries. It also allowed for the scavengers to be differentiated with respect to the formation of both solid and oil soluble by-products, with the presence / increase in carbon disulphide analysed by gas chromatography. By doing this, the method allows for improved scavenger selection on the basis of performance, compatibility and cost.
This work presents a novel method for the assessment of relative reaction rates and scavenging capacity of hydrogen sulphide scavengers. In doing so, it allows the evaluation of cost performance and suitability of different treatments and scavenger chemistries to be evaluated. Additionally, the likelihood of a scavenger chemistry fouling the refining process due to the production of reaction by-products can be investigated.