Mercury Speciation and Distribution in an Egyptian Natural Gas Processing Plant

Abstract

Unprocessed petroleum hydrocarbons often contain high concentrations of mercury (Hg), which can severely damage the metal components of a processing plant and pose a health risk to the workers and the natural environment. Although Hg removal units can significantly reduce the Hg concentration in the export products, they are often installed in the final stage of the processing plant, thus failing to protect the production facilities. In this study, Hg distribution within a natural gas processing plant was studied to identify the most effective place for a Hg removal unit. Additionally, the impact of sampling container materials and their acidification was evaluated, and Hg species in the condensate were quantified. Total Hg concentration was significantly higher in all samples stored in glass in comparison to that with plastic containers. However, the acidification effect of the containers was more pronounced for Hg in nonpolar solutions. Interestingly, the assessment of Hg distribution within the gas plant showed that the export gas is being enriched in Hg, whose concentration rose from 1.25 to 4.11 μg/Sm3 during the processing steps. The second stage separator was identified as the source of excess Hg, which partitioned from the liquid phase of condensate to the gas phase as a result of reduced operational pressure and temperature. The dominant Hg species found in the analyzed gas condensates were elemental Hg (Hg0) and inorganic Hg with the methylmercury fraction comprising up to 18%. However, it was also found that the % fraction of individual Hg species varied along the plant units most likely as a result of Hg0 migration to the export gas. Therefore, to protect all treatment facilities from Hg contamination, the Hg removal unit should be installed after the second stage compressor.

Novel field-portable high-pressure adsorbent tube sampler prototype for the direct in situ preconcentration of trace compounds in gases at their working pressures: application to biomethane

“…To the authors' knowledge, biomethane has only been in situ sampled directly on the pipelines at the grid pressure (40 bar a ) by Cachia et al 22 using a high-pressure acid bubbling impinger for the direct preconcentration of metallic TC in gas samples. 31 So far, other reported determinations of TC in high-pressure gases (typically natural gas) have always been carried out by depressurization of the gas and preconcentration at atmospheric pressure: the gas is either depressurized in situ from the pipe aer what the sampling system is installed at atmospheric pressure, 32 or it is sampled at its grid pressure in surface-treated high-pressure stainless-steel cylinders subsequently transported to the lab for depressurization and preconcentration. 29,[33][34][35][36] Depressurization is detrimental to the preconcentration of TC since, assuming the ideal gas law PV ¼ nRT, a dilution factor equal to the ratio of the high pressure to the pressure aer depressurization leads to a concentration decrease of the TC, implying larger gas volumes have to sampled at atmospheric pressure than at high pressure to trap a given amount of TC.…”

Solid Particles in Natural Gas from a Transportation Network: A Chemical Composition Study

“…These specifications ensure high quality gas for combustion but are also essential to prevent damage to facilities and protect consumer health. However, studies have revealed the presence of arsenic compounds, mercury and other metals/metalloids in natural gas from different origins at very low concentrations ranging from 10 −1 to 10 3 µg/m 3 [6][7][8][9][10][11]. These elements have well-known risks and potentially can cause industrial damage, such as through corrosion or catalytic poisoning.…”

AF4-UV-MALS-ICP-MS/MS, spICP-MS, and STEM-EDX for the Characterization of Metal-Containing Nanoparticles in Gas Condensates from Petroleum Hydrocarbon Samples

“…To the best of our knowledge, mercury speciation studies in gas condensates have mainly been focused on elemental, organic and inorganic mercury, mainly relying on separation by Gas or Liquid Chromatography and detection by ICP-MS 9 . The particulate Hg is then calculated as the difference between total Hg and the sum of all the other species.…”

“…For this reason, there is a need to identify exactly which species of mercury are present. The total amount of Hg should fulfill the following mass balance equation To the best of our knowledge, mercury speciation studies in gas condensates have mainly been focused on elemental, organic, and inorganic mercury, mainly relying on separation by gas or liquid chromatography and detection by inductively coupled plasma-mass spectrometry (ICP-MS) . The particulate Hg is then calculated as the difference between total Hg and the sum of all of the other species.…”

“…The total amount of Hg should fulfill the following mass balance equation 8 To the best of our knowledge, mercury speciation studies in gas condensates have mainly been focused on elemental, organic, and inorganic mercury, mainly relying on separation by gas or liquid chromatography and detection by inductively coupled plasma-mass spectrometry (ICP-MS). 9 The particulate Hg is then calculated as the difference between total Hg and the sum of all of the other species. More specifically, no information is found in the literature about the presence of naturally occurring Hg nanoparticles (NPs) in condensates.…”