Archive for February, 2019

Brine Recirculation RO System

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Brine recirculation is a concentrate reduction approach that has been tried in various forms to improve RO recovery. In certain forms, this approach has now been licensed and commercialised by several technology providers. Some technology providers have partnered with membrane suppliers to develop RO projection software to allow engineers and consultants to develop brine recirculation […]

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RO treatment at elevated pH

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The third and fi nal treatment step is the RO. This equipment is made up of standard components that are readily available from suppliers. Caustic is fed to the inlet of the RO to elevate the operating pH. Silica is highly soluble at elevated pH and therefore does not limit the recovery of the RO […]

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RO – Alkalinity adjustment

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The second step in the process is alkalinity removal. A forced draft degasifi er is typically used for this step. The acidic nature of the WAC ion exchange step results in the carbonate alkalinity being converted to free carbon dioxide that can be easily removed. The degasifi cation step reduces the amount of caustic required […]

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RO – Feed conditioning

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RO – Feed conditioning

One approach that can increase RO recovery is conditioning the feed water to reduce/remove or manage scaling conditions in the feed water. High efficiency RO processes use feed conditioning treatment steps that address certain feed water qualities that limit recovery, such as scaling and high oil and grease. Recoveries of more than 90% are readily […]

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RO – Hardness and suspended solids removal

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Pre-treatment steps are customised depending on the water chemistry and site-specific design criteria. The preferred hardness removal method for most industrial applications consists of a conventional lime-soda ash precipitation softening system followed by filtration and weak acid cation (WAC) ion exchange. Lime-soda ash softening in a conventional solids contact clarifier, or in a dense solids […]

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Proper mud washing is a best practice

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Proper mud washing is a best practice

Solids and grease that settle at the bottom of a desalter vessel can build up to form a mud or a sludge. It occupies space, which decreases the residence time for oil droplets to separate from water (Figure 1). If not addressed, solids can plug off draws in the effluent water header, which can lead […]

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Solids present in the incoming crude

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Solids in the incoming crude act as surfactants, which stabilise emulsions preventing the separation of water and hydrocarbons. Some of the heavier solids can be oil-coated and leave with the brine, increasing slop-oil generation. It is important to measure solids, in order to learn what potential problems may arise from desalting the crude. When analysing […]

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When oil leaves the unit

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When oil leaves the unit

There are several factors that cause emulsion stability (or hinder demulsification) and contribute to increased possibility of oil leaving the desalter with the brine. Upstream chemicals are important to the drilling, production and transportation of hydrocarbons. They protect assets, provide fl ow assurance and ensure phase separation so that produced hydrocarbons meet pipeline specifications. However, […]

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Incompatible crudes due to asphaltene precipitation

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Asphaltene precipitation can be disruptive to preheat exchangers and the desalting process. If not managed, refi ners will have fouling and corrosion challenges with their process equipment. Within a desalter, where it is critical to separate salt, solids and water from oil, asphaltenes can work against the desalting process by strengthening the emulsion stability. How […]

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Unconventional ways to keep oil in the unit

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Unconventional ways to keep oil in the unit

When prevention has not been optimally employed or implemented programmes are not achieving the right results, remediation steps might be necessary. A refinery should work with a chemical engineering team to evaluate operations and current conditions from the tank farm through to the wastewater treatment plant. Having a team that understands both process and water […]

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