Optimization, Cooperation and Design between Components and Wet Contour Regarding System Efficiency

Transcription

1 Optimization, Cooperation and Design between Components and Wet Contour Regarding System Efficiency Uwe Dortmund (Presenter) Björn Behrends KSB Aktiengesellschaft Frankenthal (D) 1

2 Purpose of Intake Structures Transport intake water to the pump in desalination plants House the pumps and auxiliary equipment Control the impact of hydraulic disturbances (into the pump) Submerged vortices Free surface vortices Excessive pre swirl of flow entering the pump Eddying effects due to sump geometry Non uniform velocity distribution at the impeller eye Transient velocity and swirl variations Entrained gas or bubbles 2

3 Pump Installation Arrangements Dry Well Pumps are not immersed in water. Water is introduced through means of a Pipe System or Hydraulic Structure / Pipe System Wet Well Pumps are immersed in water. Water is introduced by means of Hydraulic Structures 3

4 Wet Well Intake Design Standards These all give chamber dimensions that are used as a first step to determine the chamber size and are usually given as a function of the Froude Number (FD) at the pump Bellmouth entry, related to the Vortex Type (VT). VT = f (FD, S/D) S = Submergence D = Inlet or Bell Diameter S/D = FD (ANSI/HI) Hydraulic Institute (ANSI/HI) Prosser BHRA M. Padmanabhan Pump manufacture in-house 4

5 Chamber Types Inlet Types Type 1 Type 2 Type 3 Open Unlined Open Line Covered S = 100 % h2 = const. S = 66 % h2 = const. S = 40 % h2 = const. 5

6 Intake Design Process 6. Execution 1. Analysis 5. Model / CFD test 4. Optimisation 3. Design of wet contour 2. Technical assessment Total volume: ~ 1000m³ Total volume: ~ 3250m³ 6

7 Auxiliary Equipment in Seawater Intakes Screens, Trash Racks, Stop Blocks (Log), Baffle / Curtain Walls Measuring Equipment, Inlet cone, Splitters, Guide vanes What are the Hydraulic effect of these items? Assist: Straighten, Energy Dissipation Hinder: Vortices, Eddying, Stagnation 7

8 Optimisation of Seawater Intakes by Modelling Sump Model Test (SMT): Computer Modelling (CFD): Geometric Similarity Model test must CFD Simulation of Flow within the structure be an exact replica of the Prototype HI/ANSI: Q > 1136 m 3 h -1 (5000USgpm) 8

9 Vortex Formation 9

10 Example of MSF Intake Model Test and reduction potential 80m Initial Design: Area ~ m 2 40m Pump Pit Screens Structure Vol. ~ m 3 Reduction Potential: Reduction of foundation depth: ~ 4000m³ Chamber reduction: ~ 300m³ ~ 26% Operation Pumps Standby Pumps 10

11 Large Axial Flow Pump Types are Constrained by Hydraulics P[%] P Characteristic Curves P P n q PHZ H [%] SEZ Pumpen / Pumps n q SEZ Pumpen / Pumps n q PNZ Q min Q min Q min η Q - H η Q - H η Q - H η [%] NPSH NPSH NPSH NPSH NPSH NPSH Q [%] Q [%] 11 Q [%]

12 Design of Seawater Intake Pumps Ruber Bearing & Casted Pump Design Residur Bearings & Fabricated Pump Design Grooves Shaft Protection Sleeve Coating Damag e Sand Entrapme nt Diamet er Increa se Bearing Bush 12

13 LCC Reduction by Residur Bearings KSB Residur Bearings Bearing Sleeve Intermediate Layer (Rubber) Shaft Bearing Bracket Bearing Bush Locking Sleeve Cover Ceramics-based shaft guide bearing developed by KSB The RESIDUR shaft guide bearings are lubricated by the medium handled. No maintenance and low-wear design. 13

14 ROI < 2 Years Cost - Savings 2 x Pump Investment Residur Bearings Life Cycle Cost Evaluation Fabricated duplex pump with Residur bearings vs. cast Ni-Resist pump with rubber bearings Example: Seawater supply pump for MSF plant with 70 MGD Costs in EUR million 1) 3,0 2,5 2,0 1,5 1,0 0,5 A B ROI Duplex with Residur bearings less than 2 years D C 2,7 1,3 Cost savings Duplex with Residur bearings after 24 years: approx. EUR 1.4 million 2 times pump investment Ni-Resist w ith rubber bearing 0, Years 1) Investments + maintenance costs + additional energy costs Ni-Resist (electricity and lubrication) Duplex w ith Residur bearing 14

15 Compendium Optimisation of Seawater Intakes Compendium The new Intake concept enabled: Increased Availability & operation reliability Optimisation by interdisciplinary Co-operation Reduction of construction period Reduction of construction volume Decline of investment costs Decline of overall LCC Pre-Condition: Functional description of specification all parts (civil construction, mechanic, electro technique) over all concept 15

16 Intakes as a module for better solutions Which advantage provides this concept for a client, operator or consultant? How would you evaluate the marketability of this concept? How shall a possible strategy for implementation looks like? 16

17 Thank you very much for your attention Uwe Dortmund Dipl.-Ing. (TU) Senior Manager Sales and Engineering Desalination and Seawater Intake KSB AG Johann-Klein-Str. 9, Frankenthal, Germany Tel Mobile