Compact separation By Means of Inline Technology

Abstract

In a conventional separator, with the exception of mist elimination, separation is usually achieved by allowing the fluids to have a few minutes retention time under the influence of gravity. Separation equipment can be reduced in size bythe application of a centrifugal force, which is many times gravity. The result of this is that centrifugal separators can be manufactured as a very compact unit. One step further is to fabricate the equipment according to pipeline design codes so as to avoid the complexities associated with the use of pressure vessels. Inline separators are based on cyclonic technology and can be regarded as mono-cyclones. At the moment two types of separators are available and qualified for the market. The first one is a Degasser where the aim is to separate gas from a liquid continuous flow. The second type is a Deliquidiser acting in the opposite way namely separating liquid from a continuous gas stream. Besides this, liquid/liquid inline separators are in development at the moment. Besides the compactness of these inline separators, the flexibility in terms of turndown, pressure drop and efficiency is a significant benefit compared to conventional separation equipment. The paper describes several types of newly developed inline separators and inline separator-systems. In addition current installations, namely those on Statoil Statfjord B and Sleipner T platform and on the BP ETAP platform, along with their specific benefits and cost savings are discussed. It will be shown that inline technology can and has played a major role in the de-bottlenecking and upgrading of existing top-side facilities. Besides this several sub-sea applications on new and existing oil and gas fields are currently being assessed for the application of this inline technology. Introduction The inline technology described in this paper is a result of a joint development program between CDS and Statoil. Recently, inline technology has received a lot of attention due to the considerable weight and space savings that can be achieved. In addition to new build topside and sub-sea applications, inline technology can and has played a major role in the de-bottlenecking and upgrading of existing production facilities.In a conventional separator, with the exception of mist elimination, separation is usually achieved by allowing the fluids to have a few minutes retention time under the influence of gravity alone. Therefore a way in which the size of this equipment can be reduced is by the application of a centrifugal force with a magnitude that is many times gravity. The result of this is that the system can be manufactured as a very compact unit. One further step is to manufacture the equipment in accordance with pipeline design codes so as to avoid the complexities associated with the use of pressure vessels. This paper describes several types of newly developed inline separators and inline separator- systems. In addition current installations, namely those on Statfjord B, Sleipner T and ETAP, along with their specific benefits and cost savings are discussed. Inline Technology Inline separators are based on cyclonic technology and can be regarded as mono-cyclones. At the moment two types of separators are available and qualified for the market. The first one is a Degasser where the aim is to separate gas from a liquid continuous flow. Whereas the second type is a Deliquidiser acting in the opposite way, separating liquid from the gas continuous stream.

Gas-Liquid Flow in a Vertical Pipe Equipped with a Double Helical Swirl Separator Element

“…Water was defined as the liquid continuous phase while air was defined as the dispersed phase having a uniform diameter of 0.5 mm. Two set of continuity and momentum equations (i.e., one set for each phase) given in (1) and (2), respectively were solved across the fixed computational cells [12]:…”

“…the gas entrainment into waterline system in the Statoil Statfjord-B platform leads to problems with vibrations and unstable flare system [2]. The entered gas in the pipe system can be separated using a swirl flow concept where a static swirl element can be used to generate centrifugal force to separate between the liquid and gas phases [2]- [8]. Swirl elements with different geometries can be found in the open literature e.g.…”

Debottlenecking of Mature Field Production through the Use of Very Compact and Efficient Separation Equipment, Topside or Subsea

“…Statoil and CDS have pioneered the use of these kind of inline components in the past decade (2) and a large number has been successfully applied in predominantly de-bottlenecking projects. Optimizing the design of such an inline separator is not unlike optimizing the design of any cyclone type separator: separation efficiency, pressure drop, size and turn down are traded off against each other.…”