May-2024

Testing and effects of pipeline chemicals on gas processing facilities

Minimising, replacing, and properly using pipeline chemical additives causing foaming and/or solids formation will alleviate detrimental effects in amine and glycol units.

David Engel and Scott Williams
Nexo Solutions

Article Summary

Chemical additives used upstream of processing facilities are often a root cause of detrimental effects in amine and glycol dehydration units, such as solvent foaming, chemical poisoning, and equipment fouling, among others. For this reason, a study was conducted to understand the behaviour of various chemical additives when contacted with an amine solvent.

A total of 65 commercially available pipeline and upstream chemical additives commonly used upstream from processing facilities were received and reviewed in terms of their safety data sheet (SDS) documentation. Each chemical sample was contacted with lean amine solvent (methyldiethanolamine [MDEA] 50% in water) at ambient and elevated temperatures. To assess the chemical compatibility of each additive with the amine solvent, the outcome of a series of tests was observed in terms of foam formation, solid formation, and colour changes.

Figure 1 shows the various chemical additive experiments when contacted with the lean amine solvent and incubated at 60°C for five hours under atmospheric conditions. Table 1* describes the samples as labelled, named according to each SDS (as received), and numbered for future reference. The observed colour of each additive and the supplier were also listed. Compositional information was reviewed for each sample but is not listed in this discussion because of the extensive number of samples and components in each chemical additive and the fact that most compositions were proprietary and not indicated in the SDS documentation.

Bottle testing and results
Bottle testing of each chemical additive was performed by adding 0.5 ml of each additive to 10 ml of fresh lean amine provided in 40 ml sealed vials. This is essentially 5% concentration by volume. Each vial was properly mixed after the addition of the chemical additive to the amine solvent. Pictures were taken starting in one hour after mixing into the tenth day. Higher chemical additive concentrations were used to exacerbate their effects and differentiate results.

Unheated samples
Each vial was observed after 24 hours to determine if any phase separation had occurred, and several characteristics of each sample were then recorded. The results of the testing for all 65 samples are listed in Table 2.* The foaming tendency, phase separation, solids precipitation, opacity, and colour of each sample were recorded.

Of the 65 pipeline and upstream chemical additives tested with lean amine solvent, 39 displayed some degree of foaming tendency. Twenty-eight chemical additives displayed a significant amount of foam with stability, and 11 displayed a high to severe foaming. Twenty-nine samples displayed some degree of liquid phase separation, as those additives were partially or completely insoluble in the amine solvent. Eight chemical additives exhibited solids precipitation, presumably due to chemical or physical incompatibility between the formulation components and lean amine solvent. Forty chemical additives were observed to have a significant amount of haze present after agitation due to emulsification and solids dispersion.

Heated samples
The chemical additives samples with the lean amine solvent were then placed in a water bath and heated to 60ºC for approximately five hours. The samples were allowed to cool over the course of 24 hours. Each vial was observed to determine if any phase separation occurred. During the test, several characteristics of each chemical additive sample were recorded. The results of these 65 test samples are in Table 3.* The foaming tendency, phase separation, solids precipitation, opacity, and colour of each test were recorded.

Of the 65 chemical additives tested with lean amine solvent, 43 displayed some degree of foaming tendency. Twenty-eight chemical additives displayed a significant amount of foam with stability, and 13 displayed a high to severe amount of foaming. Twenty-three chemical additives samples displayed some degree of liquid phase separation, as those chemical additives were partially or completely insoluble in the lean amine solvent. Nine samples exhibited solids precipitation, presumably due to chemical incompatibility between the formulation components and lean amine solvent. Forty-one chemical additive samples were observed to have a significant amount of haze present after agitation due to effects including emulsification and solids dispersion.

The observed effects of each chemical additive sample heating (in comparison to unheated sample characteristics and 24-hour cooling) were not significant in most cases, as only sample characteristics changed. Solids precipitation was observed in one additional chemical additive sample after heating. Sample opacity was largely unchanged.However, some chemical additive samples slightly clarified or became a little hazier. Some samples were observed to have slightly changed foaming tendency after heating, but most chemical additive samples were unchanged. The most significant change in characteristics was liquid phase separation; six chemical additive samples were observed to have dissolved their discontinuous phase after heating and cooling time.

Additive analysis
The complete analysis shows that about 75% of the chemical additives tested resulted in some form of observed incompatibility. Some chemical additives displayed a greater degree of incompatibility compared to others, and continued use of those products with significant incompatibility should be replaced. At least 12 chemical additives presented moderate to severe foaming tendency of the lean amine solvent (see Tables 2 and 3)* and should be reconsidered and re-evaluated for use or potentially replaced.

Additionally, eight chemical additive samples showed solids precipitation when contacted with lean amine solvent, and 23 chemical additive samples generated liquid phase separation (see Tables 2 and 3).* All these products should be reconsidered for use or potentially replaced. Any samples with severe haziness or complete opacity should be reconsidered for use or also potentially replaced.