Gas 2024 Issue

Solids-forming chemical additives Table 5 * describes the chemical additives that caused sol- ids formation when contacted with the amine solvent, and Figure 5 shows seven of the nine samples visually. The number of process additives causing solids formation was far lower compared to the process additives causing foam stabilisation. Most of the solids formed were amber to brown in colouration. The process additives that generated solids upon contacting the amine solvent may cause solids formation if they reach the amine unit. These products were recommended to be removed prior to entering the plant or replaced. Concluding remarks From the perspective of the chemical additives used upstream of gas processing plants, a total of 65 products were evaluated in terms of their lean amine solvent com- patibility. The evaluation was partially based on colour changes once the chemical was contacted with the amine solvent. In addition, foaming tests and solids formation were also verified. These tests were performed with and without heat (60°C for five hours) and agitation. Only seven chemical additives changed colour during heat treating. Of the total 65 chemical additives tested, about two- thirds (42 out of 65) caused lean amine solvent foaming in different degrees. A total of seven chemical additives gen- erated severe foaming and should not be used in the pro- cess or anywhere upstream (see Figure 6 ). Eight products induced solids formation when exposed to the lean amine solvent and should also be avoided in both the process and upstream. Most of the chemical additive products tested were miscible in the lean amine solvent. However, 23 gen- erated a separate phase or emulsion formation. Figure 5 Samples with solids precipitation in lean amine solvents (from left to right: Sample 4, 15, 18, 19, 22, 43, 51). Samples 63, 65 not shown

samples highlighted in the table with severe foaming ten- dency. It was recommended that these seven additives be considered for replacement or replaced. Foaming tendency in methanol samples It must be noted that two out of five methanol samples were found to have foaming tendency. Methanol-based additives should not foam as they are used primarily as hydrate inhib- itors and should not contain any surfactant components in their formulation. Methanol is used for hydrate inhibition and other applica- tions, and in general should not produce foam. The meth- anol-based additives with foaming tendency were Sample 11 (Indigo RSI Methanol) and Sample 17 (Methanol Indigo 17). It is recommended that these additives should be re-evaluated before further use or replaced. The number of process additives causing solids formation was far lower compared to the process additives causing foam stabilisation. Most of the solids formed were amber to brown in colouration. The chemical additives that generated solids upon contacting the amine solvent may cause solids formation if they reach the amine unit. These products were recommended to be removed prior to entering the plant or replaced. Figure 4 Chemical additives with severe foaming. Top, from left to right: samples 7, 23, 26, 34, 42, 50, 57 before agitation. Bottom, from left to right: after agitation (+1 min)

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Gas 2024