Abstract
In this paper, the method developed by the authors to separate the inorganic materials from the hydrocarbon of the sludge deposits, which is fast and can accurately identify very small quantities of inorganic materials, has been extended to characterize the 12 types of sludge samples collected from (a) a regeneration overhead acid gas condenser, (b) water draw-off pump’s suction strainer in a gas plant, and (c) condenser, inside vessels of inlet head, and head coiler tube equipment at gas plants. The results revealed that the major phases are (a) iron sulfide corrosion products with the hydrocarbon type of mixture of diesel and lube oil for a condenser and (b) carbonate scale in the form of calcium carbonate with the hydrocarbon type of lubricant oil for sludge deposits from a suction strainer for pumps, and drilling mud in the form of barium sulfate with no organic hydrocarbon or polymer for sludge samples from a water recycling pump. Moreover, the major phases for inorganic materials built up in a condenser, inside the vessel’s inlet head, and the head coiler tube revealed that iron oxide corrosion products are found in the steam drum, and iron sulfate corrosion products are built up in the condenser. The presence of dissolved oxygen in the boiler feed water is indicated by a high wt% of iron oxide corrosion product in the form of magnetite (Fe3O4), which appeared in the inorganic materials built up in the condenser steam drum. Knowing accurately which phases and their wt% were involved in the inorganic materials can guide the field engineers to facilitate efficient cleaning of the equipment by drawing up the right procedures and taking preventive action to stop the generation of those particular sludge deposits.
Highlights
The sludge deposits that frequently accumulate inside the equipment used in the oil industry can cause failures and temporarily shut down the refinery and gas plants [1]
The main objective of the present study was to extend the new method developed by Sitepu, Al-Ghamdi, and Zaidi (2007) [1] to and accurately examine the phase composition of inorganic materials that were built up in the different equipment at refineries and gas plants — (a) a regeneration overhead acid gas condenser located at the low-pressure gas treating unit, (b) water draw-off pumps suction strainer for pumps and water recycle pump in a gas plant, and (c) condenser, inside vessels of inlet head, and head coiler tube of the sulfur recovery unit (SRU) — using advanced X-ray powder diffraction (XRD) [3,4,5,6,7,8,9] and Rietveld method [10,11,12,13,14,15,16,17,18], which are well-known techniques, both for identification of phases and for the quantification [19,20,21,22,23,24] of all the identified phases
The XRD phase identification result of the inorganic materials revealed that the deposits consisted of corrosion products in the forms of iron sulfide with some additional amounts of brimstone, carbonate scale in the form of calcium carbonate with the mineral name of calcite (CaCO3), Figure 2(a)
Summary
The sludge deposits that frequently accumulate inside the equipment used in the oil industry can cause failures and temporarily shut down the refinery and gas plants [1]. Al-Ghamdi, and Zaidi (2017) successfully experimented to separate the inorganic materials (i.e., the insoluble part or non-hydrocarbon) from the hydrocarbon (dichloromethane soluble part) of the sludge deposits that were collected from the diesel oil tank in a refinery and accurately identified and quantified the very small quantity of inorganic materials, Figure 1. They showed that the X-ray powder diffraction (XRD) data consisted of iron oxide corrosion products in the form of goethite [FeO(OH)], magnetite [Fe3O4] and lepidocrocite [FeO(OH)], iron sulfide corrosion products in the form of pyrite [FeS2] and pyrrhotite [Fe7S8], and formation materials in the form of quartz [SiO2]. Knowing which phases and their wt% were involved in the inorganic
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