Separating Oil, Water, and Gas with Weir System Separators

A weir system separator is a device that separates a mixture of oil, water, and gas into its individual components. It is commonly used in the oil and gas industry to recover valuable resources and reduce environmental impact.

There are different types of weir system separators, such as horizontal, vertical, and spherical. Each type has its own advantages and disadvantages depending on the flow rate, pressure, temperature, and composition of the mixture.

One of the main components of a weir system separator is the weir plate, which is a barrier that controls the level and flow of the liquid phases. The weir plate can be either an overflow weir, which allows the oil to spill over the top of the plate, or a bucket and weir, which collects the oil in a separate compartment.

The following table summarizes some of the features and benefits of different types of weir system separators:


Type Features Benefits
Horizontal with overflow weir – Fluid enters the vessel and hits an inlet diverter, which releases the gas by breaking the surface tension of the liquid. <br> – The oil separates and forms a layer above the water. An interface level controller maintains the oil-water level and signals a dump valve to release water as needed. <br> – The oil spills over the top of the overflow weir and a level controller operates a dump valve to maintain the oil level in the oil bucket. <br> – Gas rises to the top of the separator and exits through a mist extractor and a back pressure control valve. – Simple and robust design. <br> – Low maintenance and operating costs. <br> – High efficiency and reliability. <br> – Suitable for high gas-liquid ratios and low liquid-liquid ratios.
Horizontal with oil bucket and water weir – Similar to the horizontal with overflow weir, except that the vessel does not require an active interface controller. <br> – As the oil separates on top of the water, it spills over the weir plate and into the oil bucket. The oil level in the bucket is controlled by a level controller and a dump valve. <br> – The water flows under the oil bucket and over the water weir, where it is controlled by another level controller and dump valve. – Same as the horizontal with overflow weir, plus: <br> – No need for an interface controller, which reduces the complexity and cost of the system. <br> – Better control of the oil and water levels and quality.
Vertical with interface control – Fluid enters the vessel and hits an inlet diverter plate, which separates the bulk of the gas upon entry. <br> – The inlet divertor also directs the fluid down along the side wall, minimizing disturbances to the fluid. <br> – Lower in the vessel, the fluid encounters a splash guard, which protects the interface level controller from false readings. <br> – As the oil separates, the interface level is determined. The interface level controller opens the water dump valve when the interface level rises. <br> – The oil level is also controlled by a liquid level controller, which opens the oil dump valve when the oil level rises. <br> – Gas exits through a mist extractor and a back pressure control valve. – Compact and space-saving design. <br> – Suitable for high liquid-liquid ratios and low gas-liquid ratios. <br> – Good performance under varying flow conditions. <br> – Less susceptible to foaming and emulsion problems.
Vertical with a downcomer and spreader – Similar to the vertical with interface control, except that the fluid enters the vessel through a downcomer pipe, which distributes the fluid evenly across the cross-section of the vessel. <br> – The fluid then encounters a spreader, which enhances the separation of the liquid phases by creating a thin film of fluid. <br> – The rest of the process is the same as the vertical with interface control. – Same as the vertical with interface control, plus: <br> – Improved separation efficiency and quality. <br> – Reduced turbulence and mixing of the fluid. <br> – Increased capacity and flexibility of the system.

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