137- Discussion on the advantages and disadvantages of the design of the three-phase separator and core internal components system for CNPC International’s Phase III Hafaya project in Iraq

The attached figure is an excerpt from the layout diagram of this three-phase separator.

This post was last edited by luoli519 on 2019-12-5 at 20:00. The main advantages of this design are indicated in the figure below, and they are worth considering by everyone.

This post was last edited by luoli519 on 2023-9-26 at 16:49. As shown in the figure, advantage 1 is that a vaned separation assembly is installed at the inlet of the three-phase separator. The three-phase separators provided by many companies, both domestic and international, often lack this inlet separation assembly; as a result, the liquid phase flow within the separator contains numerous small dispersed bubbles, while the gas phase flow carries a large amount of liquid droplets and foam. This, in turn, affects the stable and efficient operation of the subsequent separation components. G50B-1 is the image of this inlet separation assembly. Data such as the length and width of the components within the inlet separation assembly, the number of vanes in the assembly, the central angle, the tip angle, the radius of curvature at the vanes’ joints, the inward extension distance of the vanes’ separation components, and the outward expansion distance of the vanes must be determined through precise dynamic separation calculations and a configuration design system platform; it is not possible to assume these values arbitrarily, as doing so will significantly affect the performance of the assembly.

Advantage 2: The weir plate features an adjustable structure. The weir plates found in many three-phase separators that people see are usually of traditional design, being fixed-type weir plates with fixed heights and widths that cannot be adjusted. However, in actual operation, the liquid-liquid phase ratio in the feed stream often varies significantly from the designed value, and the position of the liquid-liquid interface also changes, thereby affecting the efficiency of liquid-liquid phase separation. The adjustable weir plate allows the height of the weir to be adjusted according to the ratio of the two liquid phases; as the height of the weir changes, the width of the weir plate within the radial cross-section of the separator also changes accordingly. An adjustable weir plate must be one whose height and width can both be adjusted. If the ratio of the liquid-liquid phases in the feed changes, an adjustable weir plate can improve the separation of these phases according to the operating conditions; however, this adjustable weir plate alone is far from sufficient, and this is one of the shortcomings that will be discussed later in this post.

This post was last edited by luoli519 on 2019-11-10 at 18:51. Advantage 3: This three-phase separator is equipped with a bottom purge internal component set, which allows for the regular removal of solid particles such as sediment and crystalline substances that accumulate at the bottom of the separator. Especially in the oil and gas processing and transportation processes, as well as in the three-phase separators used for the alkaline washing of organic substances, a bottom purge internal component set is an essential installation ； Otherwise, the accumulation of solid phase at the bottom of the three-phase separator will increase, which will inevitably affect the residence time of the liquid phases inside the three-phase separator as well as the separation efficiency.

This post was last edited by luoli519 on 2019-11-10 at 19:38. Advantage 4: A vaned separation internals set is installed at the gas-phase outlet of the three-phase separator, which greatly helps to improve the separation accuracy and efficiency of the separator for the output gas stream. This prevents liquid accumulation in subsequent gas transmission pipelines as well as operational failures in downstream equipment that rely on gas supply. This can be confirmed from the technical requirements for the internal components of the vapor separation head in the attached drawings.

Advantage 5: This three-phase separator is equipped with a heating and insulation system. It should be noted that the oil-water mixture obtained from oil and gas fields often has a high viscosity; even at room temperature, the viscosity of the oil phase can exceed 10^3 cp. The dispersed water phase and gas phase contained within the oil phase find it difficult to be released rapidly from this highly viscous oil phase within a specified time frame. It is necessary to heat the system in order to rapidly reduce the viscosity of the oil phase, thereby allowing the dispersed water phase and gas phase carried within the oil phase to be quickly released from the highly viscous oil phase within a specific residence time.

Apart from the design advantages of the aforementioned three-phase separator, this design is not perfect either; it has the following major shortcomings, as shown in the attached diagrams:

Shortcoming 1: Lack of liquid-liquid coalescing internal components. Since process separation technologies require the residual oil content in the produced water to be below 0.05%, meeting such high separation standards is difficult using solely the conventional, simple, and inefficient method of pure gravitational sedimentation with no coalescing internals, especially given the high viscosity of the oil phase. Therefore, a liquid-liquid coalescing internals assembly must be installed, such as the G56 type vane-type liquid-liquid coalescing internals assembly. To ensure the efficient and stable operation of the liquid-liquid coalescing internals under conditions of fluctuating feed rates and large fluid volumes, ballast elements can also be installed in advance.

This post was last edited by luoli519 on 2023-9-26 at 16:50. The attached image shows a photo of the G56 type vane-separating and coalescing internal component set for everyone’s reference: