twister supersonic separator

Twister? Supersonic Separator The Twister? Supersonic Separator is a unique combination of physical processes producing a completely revolutionary gas conditioning system. Condensation and separation at supersonic velocity is the key to achieving a significant reduction in both capital and operating costs. Applications Twister can be used to condense and separate water and heavy hydrocarbons from natural gas. Current applications include any combination of the following: l Water Dewpointing (Dehydration) l Hydrocarbon Dewpointing l Natural Gas Liquids extraction (NGL/LPG) These applications can be applied in the following market areas: l Underground gas storage l NGL recovery New applications under study include bulk H2S removal upstream sweetening plants, landfill gas treatment and sub-sea gas processing. The simplicity and reliability of Twister technology enables de-manned, or not normally manned, operation in harsh onshore and offshore environments and is expected to prove to be a key enabler for sub-sea gas processing. Twister BV is currently working on a joint technology development project with Petrobras in Brazil for sub-sea gas processing using Twister technology. In addition, the compact and low weight Twister system design enables de-bottlenecking of existing space and weight constrained platforms. Benefits Condensation and separation at supersonic velocity is the key to some unique benefits. The residence time inside the Twister Supersonic Separator is only milliseconds, allowing no time to form for hydrates to form and avoiding the requirement for hydrate inhibition chemicals. The elimination of the associated chemical regeneration systems avoids harmful BTX emissions to the environment and the expense of chemical recovery systems. The simplicity and reliability of a static device, with no rotating parts which operates without chemicals, ensures a simple facility with a high availability, suitable for unmanned operation in harsh and/or offshore environments. Supersonic separation also results in compact and low-weight facilities which can be installed on an unmanned, minimum facilities platform, not much larger than a simple wellhead platform or can be used to de-bottleneck existing space and weight constrained platforms. Key benefits may include: 1. No chemicals or reduced chemical consumption – eliminating or reducing chemical logistics, storage, regeneration and recovery systems. 2. Closed system – no environmental emissions (e.g. BTX). 3. Compact and low weight design. 4. No rotating parts – eliminating lubrication systems and reducing maintenance costs. 5. Simple and reliable – ensuring a high availability, enabling de-manned, or not normally manned, operation and improving safety performance. 6. Near instant start-up. 7. Higher Natural Gas Liquid (NGL) extraction resulting in improved revenue streams. 8. Significant capital and operating expenditure savings. 9. To assess the feasibility and specific benefits for your application, please contact the Twister office for a free screening study How it works The Twister? Supersonic Separator has thermodynamics similar to a turbo-expander, combining the following process steps in a compact, tubular device: l expansion l cyclonic gas/liquid separation l re-compression Whereas a turbo-expander transforms pressure to shaft power, Twister achieves a similar temperature drop by transforming pressure to kinetic energy (i.e. supersonic velocity): l Multiple inlet guide vanes generate a high vorticity, concentric swirl (up to 500,000g) l A Laval nozzle is used to expand the saturated feed gas to supersonic velocity, which results in a low temperature and pressure. l This results in the formation of a mist of water and hydrocarbon condensation droplets. l The high vorticity swirl centrifuges the droplets to the wall. l The liquids are split from the gas using a cyclonic separator. l The separated streams are slowed down in separate diffusers, typically recovering 70 – 75% of the initial pressure. l The liquid stream contains slip-gas, which will be removed in a compact liquid de-gassing vessel and recombined with the dry gas stream. Figure 1 shows a cross-section of a Twister tube with typical process conditions. Figure 2 compares the thermodynamics of Twister with conventional Joule-Thomson expansion. In this example, the same feed conditions (100 bar/1450 psi, 40°C/104°F) and the same pressure drop (30%) has been assumed for both processes. System Design The above figure shows a Process Flow Diagram for a typical Twister? System. Twister is a low temperature separation process, for which performance can be optimised by inlet cooling. This can be achieved by heat integration using the cold gas exiting Twister, supplemented with air or seawater cooling if required. The inlet separator upstream of the Twister tubes is designed to remove produced liquids and prevent carry-over of slugs and solids. In designing a gas conditioning system based on Twister technology, the following issues need to be considered: l Twister is a fixed actual volumetric flow device. The gas velocity at the throat of the inlet nozzle will always be exactly Mach 1, fixing the flow through the tube. Some turndown flexibility can be achieved by adjusting the operating pressure. However, a typical Twister system will include multiple Twister tubes connected together to provide the required turndown flexibility. l Twister is a pressure ratio device. For any design pressure, the gas will expand to 30% of feed pressure mid Twister and will recompress to 65 to 80% of the feed pressure on exiting Twister. Higher pressure drops may be required for efficient NGL recovery. The adjacent figure shows a typical layout developed for an offshore application. Up to six compact Twister tubes, each with a capacity of up to 3 million Sm3/d (105 MMscfd), can be mounted in a vertical position on a vertical liquid degassing vessel. This compact, low weight arrangement provides a revolutionary gas conditioning solution for unmanned minimum facilities platforms and can be a key enabling technology for de-bottlenecking existing space and weight constrained platforms. Twister vs Competition Commercial Benefits l Significantly lower life cycle costs compared to conventional silica gel and glycol based systems. l Near instant start-up – potential revenue improvement from on-demand trading? l Minimal OPEX costs – since Twister does not have any rotating parts and has minimal maintenance (6-yearly tube inspection scheme), eliminating operator intervention requirements, OPEX costs are lower than for conventional technologies. No external heating required for Twister Gas Conditioning Package. Technical Benefits l Simple and reliable – ensuring a high guaranteed availability (>98%), enabling de-manned operation and improving safety performance. l Small(er) footprint l No fouling/poisoning of system resulting in replacement of dehydration bed (as for desiccants) and efficient turn down capability, fully process automation in control systems ensuring safer and more efficient operation. l No downtime constraints due to utility equipment failures (glycol pumps, regen systems, etc) Twister subsea gas dew-pointing Offshore gas production is faced with increasingly deeper water developments and longer tie-back distances. This trend is leading to a variety of flow assurance challenges, such as hydrate formation, wax deposition and degraded hydraulic performance issues. Twister offers an unrivalled subsea processing tool which simultaneously dehydrates the gas and removes heavy hydrocarbon components in a single compact modular device. The technology manages the above-stated flow assurance challenges and, as such, has been identified as a key enabler for future subsea developments. Twister BV and FMC completed a feasibility study in 2002 to investigate the feasibility of a subsea Twister system. No show-stoppers were identified, although the study did highlight that some – non Twister – components require further development and qualification, prior to subsea use. Twister BV, FMC and various other partners subsequently secured EU funding for a four year development programme, which resulted in further development of Twister subsea technology. A joint technology development co-operation agreement was signed with Petrobras in 2006, to test, qualify and develop a subsea dewpoint system using Twister. Under this agreement, Twister BV has since supplied a Twister module to Petrobras which has been installed at an existing onshore gas plant in Brazil, to allow Petrobras to further evaluate the technology. The unit was started up in November 2009 and has operated successfully to date. The second phase of the agreement is expected to kick off during 2010 and will comprise an engineering study for the subsea test on the Petrobras Canapu field. This field is located 20.5 kilometers from a nearby FPSO, in 1600 metres water depth. Benefits of Twister subsea gas dew-pointing Twister dehydration and dew-pointing enables dry, single-phase export, eliminating flow assurance risks and limitations associated with wet, multiphase export systems. Benefits of subsea gas conditioning include: l Hydrate prevention: As Twister dehydrates the gas, the continuous use of MEG (or other hydrate inhibitors) can be eliminated or lowered substantially. Dedicated chemical pipelines are no longer required, but can be incorporated in the Twister control umbilical. In turn, the problems associated with MEG regeneration equipment (i.e. incompatibility with other chemicals, salt deposition) are eliminated or dramatically reduced. l Improved hydraulic performance of pipeline : Multiphase export limits both pipelline turndown flexibility and maximum pipeline size. This usually necessitates multiple smaller diameter pipelines and often eliminates the flexibility to tie-in future developments. By splitting the flow into separate single-phase gas and condensate streams, multiphase flow is avoided and future tie-ins facilitated. Terrain or severe riser slugging is prevented, and costly slug-catchers can be avoided. Routine pigging liquid hold-up mitigation, which is a costly and risky operation, can also be avoided. The elimination of pigging loops also halves the amount of installed subsea pipelines. l Corrosion prevention: Twister subsea dew-pointing is expected to be a particularly attractive option for corrosive services. Due to the process Twister enables most corrosive elements to be removed from the gas, and hence may avoid the need to install expensive corrosion resistant alloy (CRA) pipelines. Effective corrosion management for wet gas carbon steel (CS) pipelines normally requires routine pigging to maintain a protective chemical film on the inside wall of the pipeline. This requirement is costly and cumbersome for subsea developments. Twister subsea dew-pointing minimises the need for extensive subsea pigging. l Field enabling technology by cost saving: Using Twister subsea gas treatment, an otherwise un-economical or marginal field can be developed without the need to install an offshore surface facility. Twister enables direct gas and liquid export lines from the subsea wellhead to the onshore facility, or to a platform in shallower waters. This enables the economic development of stranded gas fields. The ability to hot tap new fields directly into existing export lines allows asset life extension, further reducing costs for field development, as no new pipelines are required. By combining Twister subsea gas dew-pointing with currently under-development subsea gas compression, offshore surface facilities may in the future be totally eliminated with the associated substantial commercial benefits. Experience To date Twister systems have accumulated over 200,470 running hours. Twister technology has been operated at the following sites under various pressures, flows and compositions. NAM Zuiderveen– The Netherlands 1998 NAM Barendrecht– The Netherlands 1999-2000 NAM Leermens– The Netherlands 2000-2001 SPDC Utorogu– Nigeria 2001-2002 NAM Leermens– The Netherlands 2002-2003 Gasunie – The Netherlands 2005-2006 Petronas/SSB B11– Malaysia 2003-present SPDC Okoloma – Nigeria 2009 start-up Petrobras – Brazil 2009 start-up Ecopetrol – Colombia 2010 start-up     The Petronas/Sarawak Shell B11 contract was secured in 2002 and comprises a system using 12 Twister tubes handling 17 MMSm3/d (600 MMSCFD) of sour gas. Condensate that is formed is dried in a static coalescer and spiked back into the dry gas. This plant has now been in continuous operation for over six years and has performed better than the contractually agreed 98% availability. Twister technology was selected by Shell Petroleum Development Company (SPDC) on a 120 MMSCFD onshore dehydration and dewpointing application for fuel gas treatment for the Afam power plant in Nigeria. The Twister module comprises 6 Twister tubes. The system was successfully started up in April 2009 and has operated with 100% availability to date. Twister technology has been awarded a contract by Ecopetrol to supply Twister technology for an onshore, 65 MMSCFD, dehydration and hydrocarbon dew pointing plant in Colombia. The Twister tubes have been manufactured and shipped to Colombia and start-up is planned during Q3 2010. Recent Projects Twister BV was awarded a contract by Petrobras in April 2007 for an onshore dehydration/dew-pointing test module. This test is part of a joint technology co-operation to develop Twister technology for subsea applications. The Twister module has been delivered to Petrobras and installed. The plant started up in Oct 2009 and has run well to date. Twister BV has completed an engineering contract for Petronas Carigali Sdn Bhd to jointly develop a basic engineering package for a Twister dehydration module which will replace a TEG unit on an existing platform offshore Malaysia. The equipment supply contract is expected in Q4 2010. Twister technology has also been selected by PTT PCL in Thailand for a brownfield debottlenecking application for enhancing NGL recovery at their onshore gas processing plant at Ma Thab Phut. We have completed a FEED contract and expect the equipment supply contract to be awarded in 2011. Twister Supersonic Separator Screening Tool Twister BV has produced a simple screening tool to help customers to identify suitable applications for Twister Supersonic Separation technology. Download Screening Tool for Twister Applications.pdf To date Twister systems have accumulated 200,470 system running hours in total including commercially operated units, pilot plants and closed-loop testing. LPG/NGL Recovery Twister technology can recover significantly more NGL than a turbo-expander and JT system without the use of hydrate inhibition chemicals. Whereas the hydrate formation temperature limits the operating temperature in the LTS for a turbo-expander and JT system, the hydrate formation temperature only limits the Twister system at the inlet of the Twister tube. No hydrate formation takes place inside the Twister tube due to the very short residence time, and hydrates in the secondary outlet of the Twister tube are managed in the Hydrate Separator using heat input. In other words, the minimum acceptable temperature in the LTS for a turbo-expander and JT system is more or less the same as the minimum acceptable temperature at the Twister tube inlet. Therefore Twister is able to expand much deeper into the phase envelope and recover significantly more NGL than a turbo-expander and JT system without the use of hydrate inhibition chemicals. An independent study to compare the NGL recovery rate of Twister and a JT system has been conducted by Genesis Oil & Gas covering a wide range of water contents, gas compositions and operating conditions. The recovery rates for LPG, condensate and C3+ have been presented in figure 1 and figure 2. Figure 1: C3+ recovery as function of water content for Twister and JT-LTS Figure 2: NGL recovery as function of water content for Twister and JT-LTS using a chiller This study clearly showed that Twister recovers significantly more NGLs down to very low water contents. The JT system can utilise the maximum possible heat integration at these very low water contents, without hydrate formation in the LTS, hence improving the NGL recovery rate, but the NGL recovery rate for the Twister system is still better even at these water contents. By applying a chilled water and/or a mechanical refrigeration unit the Twister inlet temperature can be reduced again to just above the hydrate formation temperature. As expected, this results in a further increase in the NGL recovery as is presented in figure 2. The Twister C3+ recovery increases by approximately 10% (from 50-60% range to 60-70% range) when upstream chilling is applied. The JT-LTS system does not benefit from adding a chiller, since its heat integration is limited by the water in the gas. The same results can be expected for non bone-dry gas applications, where Twister is compared to a turbo-expander, as the water content will limit its LTS temperature.