Mechanical Seals for. Ramesh Krishnappan AESSEAL ICEPIM 2015

Transcription

1 Mechanical Seals for Pipeline Applications Ramesh Krishnappan AESSEAL ICEPIM 2015 International ti lconference on Pipeline Integrity management

2 Introduction This presentation will focus on the application of mechanical seals in pipeline pumps, covering the transmission of crude oil and refined products such as fuel oils, gasoline's and natural gas liquids (NGL), for example propane and ethane. Included in this discussion will be pipeline systems that transport multiple products through the same pipeline as well as mixtures of NGL. These batched product pipelines present difficult sealing applications because the pumped products can range from light NGL products to heavier gasoline products. Additionally, some of these same pipeline systems can also be used to transport crude oils.

3 Pipeline Categories In general, pipelines can be classified in three categories depending on purpose: Gathering pipelines Group of smaller interconnected pipelines forming complex networks with the purpose of bringing crude oil or natural gas from several nearby wells to a treatment plant or processing facility. In this group, pipelines are usually short a couple of hundred metres and with small diameters. Also sub sea pipelines for collecting product from deep water production platforms are considered gathering systems. Transportation pipelines Mainly long pipes with large diameters, moving products (oil, gas, refined products) between cities, countries and even continents. These transportation networks include several compressor stations in gas lines or pump stations for crude and multiproduct pipelines. Distribution pipelines Composed of several interconnected pipelines with small diameters, used to take the products to the final consumer. Feeder lines to distribute gas to homes and businesses downstream. Pipelines at terminals for distributing products to tanks and storage facilities are included in this group.

4 Pipeline Types Gas Gas production, and in particular Liquefied Natural Gas (LNG), is expanding at a rapid rate. With a range of cryogenic pumps suitable for pumping LNG, Pump OEM s specialize in building ultra large high pressure send out pumps for the latest generation of LNG terminals. Multiphase Multiphase pumping is increasingly used to boost well production. Latest developments include a subsea version of the pump for direct boosting at the well head. CO 2 Capture, transportation and storage of CO2 is a developing market with CO2 being used as an injection medium or stored in depleted wells. Pump OEM s are active in this field supplying CO2 pipeline transportation and high pressure injection pumps. Crude Oil / NGL Transporting crude oil or refined products in pipelines across continents from production centers to market is a key part of the modern world s energy distribution infrastructure.

5 Pipeline Lay out Desired material throughput values as well as circumstantial factors along the pipeline route are considered in designing and locating pump stations. ti Because there are a multitude of ways in which h the desired d operating conditions can be obtained and sustained, the outfitting and location of pump stations are also ofteninfluencedbyeconomics, typicallyrepresentinga compromise between few large capacitypump stations and a greaternumberof smaller capacity stations.

6 Pumping Stations At a minimum, pump stations include pumps (components that actually contact the fluids in the pipeline and provide kinetic energy) and prime movers (power sources that provide power, typically some form of mechanical energy) to the pumps. To facilitate maintenance and to prevent disruptions of pipeline operation as a result of equipment failure, most pump stations use several pumps arranged in parallel fashion. Typically, all but one of the pumps is capable of producing the desired operating pressures and throughputs, so some pump is constantly off line andinstandby. Typical pump station configurations involve at least three pumps connected to the pipeline in parallel. Two of the three pumps operate while the third remains available, if needed, or in the event of a failure of one of the operating pumps. Such a configuration also allows pumps to be taken off lineformaintenanceor replacement without affecting the operating status of the pipeline.

7 Pump Designs Pumps of various designs are used in crude oil and petroleum product pipelines. Two fundamental pump designs are in common use: centrifugal pumps and positive displacement pumps. Centrifugal pumps are preferred for moving large volumes of material at moderate pressure, while positive displacement pumps are selected for moving small volumes of material at higher line pressures. Centrifugal pumps consist of two main components: the impeller and the volute. The impeller, the only rotating component of the pump, p, converts the energy it receives from the force that causes its rotation into kinetic energy in the fluid being pumped, while the volute converts the kinetic energy of the fluid into pressure. Positive displacement pumps can be of various designs; however, two designs predominate in pipeline applications: reciprocating and rotating pumps. Rotating pumps are often the pump design of choice for viscous fluids such as crude oils. Unlike a centrifugal pump where power demands rise sharply with increasing fluid viscosity, the performance of rotating pumps is generally unaffected by variations in either fluid viscosity or line pressure.

8 1. Pipeline Seal Designs CFC / CFFC up to 60 barg / 60 m/s 64% to 69% Face balance HPVS/HPVD up to 90 barg / 60 m/s 80/70 Face balance, Hydro pads

9 2. Demanding Applications 60 bar plus Pressures Bigger Shafts / high velocity Reverse pressure capability Dry running possibility High Viscous (Crude) Volatile fluids (Ethane & Propane) Sand Particles, Abrasive Pipe Rouge Start/Stop operations Cooling Water availability at remote locations. Remote Locations Complex Supply Systems Poor Equipment Conditions Small Seal Chamber

10 2a. Seal Arrangements Single Seals Dual Seals Contact Wet Primary/ Containment Secondary

11 2a. Seal Arrangements Dual Seals Liquid Pressurized Face to Face Back to Back Gas Pressurized Face to Face Back to Back Face to Back

12 3. Pump Types Crude Oil and Refined Product Pipeline Pumps Mainline/Booster Pumps Single and two stage between bearings Multistage, horizontal split case Multistage, radially split double case Multistage vertical canned Twin screw multiphase Auxiliary Pumps Single stage g overhung Vertical in line Submersible motor Single stage and multistage vertical wet pit Single stage and multistage t vertical canned Service specific specialty designs Water Pipeline Pumps Single and multistage overhung Axially split, single stage between bearings Vertical turbine Submersible motor Horizontal, multistage ring section Slurry Pipeline Pumps Single stage overhung Hard metal Metallic and non metallic lined Reciprocating positive displacement CO2 Pipeline Pumps Single stage, bt between bearings, radiallysplit lit Multistage, horizontal split case Multistage, radially split double case

13 3a. Pump Types and Models Sulzer Sulzer Single and two Stage Pumps

14 3b. Pump Types and Models Sulzer Sulzer Axially Split Pumps

15 3c. Pump Types and Models Sulzer Horizontal Split Diffuser Pumps of Sulzer Bingham Pumping Stations at remote locations

16 3d. Pump Types and Models Heavy Crude Oil pumping : Bornemann & Leistritz it Screw pumps used in pipeline applications are of two types: 1) Twin-screw pumps which h are used predominantly at pipeline boosting stations and Terminals. 2) Three-screw pumps to boost pressure from laterals to the main pipeline. 4x Seals per Pump... Tight Space!

17 3e. Pump Types and Models : Flowserve DVSH/LPN/LPLD (BB1) Axially Split, Single Stage Flows to m3/h ( gpm) Heads to 565 m (1854 ft) Pressures to 150 bar (2175 psi) Speeds to 6000 rpm DMX (BB3) Aill Axially Split, Multistage t Flows to 2950 m3/h ( gpm) Heads to 2130 m (7000 ft) Pressures to 275 bar (4000 psi) Speeds to 6000 rpm

18 Design Features Some of CFFC seals working satisfactorily in Pipeline Applications ranging from 65mm to 100mm size. These seals have been fitted in Stork Pumps, Ensival lmoretpumps and OLMX Guinard dpumps for pressures ranging from 23 bar to 65 bar. The pumped fluids include Mineral Oil, Crude Oil & Naphtha

19 Typical API Plans in Pipelines Research has proven that the best way to prevent mechanical seal failure is in using effective Seal Support Systems. This means that no matter how well designed your mechanical seals are, without a reliable Seal Support System there is still the possibility of your mechanical seal failing. Because sealing applications on product pipeline pp pumps p are critical to pipeline pp operation, the use of dual (tandem, double or dry running secondary) seals should be considered. Dual seals can maintain low leakage rates while providing improved safety. A tandem seal is two seals operating in series with the secondary seal usually of the sameconfiguration as the primary seal. An unpressurized seal reservoir, Plan 52, is required to support the operation of the secondary seal. A double seal is usually two seals sealing in opposite directions. This seal is usually supported with a pressurized seal reservoir, Plan 53A or 53B or 54. Dry running secondary seals operate in tandem arrangement without the seal reservoir required for liquid tandem arrangements. The innovative and reliable Seal Support System Range at AESSEAL gives customers the confidence to remove this root cause of mechanical seal failure.

20 API Plan 53B Typical API Plans in Pipelines Pressurized barrier fluid circulation in outboard seal of dual seal configuration. Circulation is maintained by using pumping ring in running condition and with thermosyphon effect in stand still condition. The pressure is maintained in the seal circuit by a bladder accumulator. 1. Keeps barrier fluid and pressurized gas (N2) separate by using a bladder. 2. Heat is removed from the circulation system by an air cooled or water cooled heat exchanger. 3. Being a stand alone system does not rely upon a central pressure source. Hence much more reliable than a Plan 53A. 4. In no case media leakage to atmosphere. Sample System

21 4. Opportunities Global Source : Pipeline Knowledge & Development

22 4. Opportunities Americas Imbalances provide pipeline opportunities Source : Pipeline Knowledge & Development

23 4. Opportunities USA Source : National Pipeline System Mapping, USA

24 4. Opportunities Asia Source : Pipeline Knowledge & Development

25 Pipeline Operators Enterprise Products Partners L.P. provides midstream energy services to producers and consumers of natural gas, natural gas liquids (NGLs), crude oil, refined products, and petrochemicals in the United States and internationally

26 Pipeline Operators SunocoLogisticsPartnersL.P. engages in the transport, terminalling, and storage of crude oil and refined products in the United States.

27 Pipeline Operators Enbridge Inc. operates as an energy transportation and distribution company in the United States and Canada. Its Liquids Pipelines segment operates common carrier and contract crude oil, natural gas liquids (NGL), and refined products pipelines and terminals.

28 Pipeline Operators ONEOK Partners, L.P. engages in the gathering, processing, storage, and transportation of natural gas in the United States. It operates in three segments: Natural Gas Gathering and Processing, Natural Gas Pipelines, and Natural Gas Liquids.

29 Thank you.