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April 9-12, 2006 APPA 2006 Engineering & Operations Technical Conference Sacramento, California Reduction of Rainwater Intrusion Into Deerhaven Unit 2.

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Presentation on theme: "April 9-12, 2006 APPA 2006 Engineering & Operations Technical Conference Sacramento, California Reduction of Rainwater Intrusion Into Deerhaven Unit 2."— Presentation transcript:

1 April 9-12, 2006 APPA 2006 Engineering & Operations Technical Conference Sacramento, California Reduction of Rainwater Intrusion Into Deerhaven Unit 2 Coal Pile Reclaim System John B. (Jack) Miller – Black & Veatch Ali McDaniel – Gainesville Regional Utilities

2 04/09/2006JBM(8) - 2 Overview Describe the Process That Lead to the Decision to Install the Cover Review the Design Development Design Features Construction Process Examine the Initial Measurements of Its Effectiveness Gainesville Regional Utilities (GRU) Recently Installed a Rain Shield Over the Coal Reclaim for Their Deerhaven Unit 2. This Presentation Will:

3 04/09/2006JBM(8) - 3 About the Authors Ali McDaniel Material Science Engineer – GRU’s Project and Construction Manager for This Project Jack Miller Mechanical Engineer – Black & Veatch’s Project Manager for the Feasibility Study and Detailed Design

4 04/09/2006JBM(8) - 4 About GRU GRU Is a Municipally-Owned Utility Serving the City of Gainesville, Florida for 100 Years Gainesville Is Located in North Central Florida GRU Serves 87,000 Retail and Wholesale Customers Owns and Operates Two Power Plants, John R. Kelly and Deerhaven Generating Stations Installed Capacity of 611 MW to Serve a Peak Demand of 450 MW

5 04/09/2006JBM(8) - 5 About Deerhaven Unit 2 Deerhaven Unit 2 Is a 235 MW Pulverized Coal-Fired Steam-Electric Generating Unit Commissioned in 1982 Burns Low Sulfur East Kentucky Compliance Coal

6 04/09/2006JBM(8) - 6 Aerial View of Deerhaven Generating Station Looking North Northeast

7 04/09/2006JBM(8) - 7 Problem Definition Rain!! Wet Coal O&M Impacts Plugging in the Reclaim, Conveying Storage and Milling Systems Negative Impact to Thermal Efficiency Can Cause Significant Unit Derates and Relatively Expensive Replacement Power In 2003, Wet Coal Effects Directly Resulted in the Need for 12,879 MWh of Replacement Energy Annually58 inches max. 48 inches avg. 34 inches min.

8 04/09/2006JBM(8) - 8 Overview of Coal Handling System

9 04/09/2006JBM(8) - 9 Highlights of Coal Handling Operations

10 04/09/2006JBM(8) - 10 Highlights of Coal Handling Operations Coal Is Delivered by Unit Trains Carrying About 11,000 Tons Unloaded From Track Hopper at 3,000 TPH Conveyed to Dual Discharge Fixed Boom Stacker Can Build 1,800 Ton Conical Coal Pile on North and South Sides

11 04/09/2006JBM(8) - 11 View of Stockout Tower Looking West

12 04/09/2006JBM(8) - 12 Highlights of Coal Handling Operations Reclaim System Operates at 500 TPH (2" x 0" Coal at 15% Moisture) Four Below-Grade Hoppers: Three on the South (Active Reclaim) One on the North (Emergency Reclaim) Hoppers Feed a Common 30-Inch Belt Conveyor Conveys Coal to the Six Storage Bunkers Via a Crusher Tower Bunkers Hold 18 Hours of Fuel at Typical Burn Rate Coal Is Fed to Burners Through B&W MPS 75N, DVS Rotating Classifier Pulverizers

13 04/09/2006JBM(8) - 13 Graphic Display – Stockout and Reclaim System

14 04/09/2006JBM(8) - 14 Coal Pile Management Equipment Excess Coal Is Moved From Stockout Pile to Long-Term Storage Using Dozers and Front-End Loaders Takes Three Machines Three Days to Move and Spread 11,000 Tons

15 04/09/2006JBM(8) - 15 Analysis and Development of Solution

16 04/09/2006JBM(8) - 16 Analysis and Development of Solution Wet Coal Effects Had Been Manageable Until Coal Fines Content Increased In Late '90s, Began Using Lower Sulfur East Kentucky Coal Sizing Changed From Nominal 2" x 0" to ¾" x 0" Fines Increased Considerably More Conducive to Plugging When Wet More Conducive to Excessive Ratholing Above the Reclaim Hopper

17 04/09/2006JBM(8) - 17 Ratholing at the Center Reclaim Hopper Ratholing Provides Direct Path for Rainfall and Runoff to Enter the Reclaim Hopper and Flow Directly Onto Reclaim Belt  Primary Source of Entrained Water in the Coal and Attendant Problems

18 04/09/2006JBM(8) - 18 GRU Study Correlation Between Rainfall and Need for Replacement Energy Due to Unit Derates Short-Term Rain Events of Greater Than 2 Inches Cause Derates on a Proportional Basis  More Rain, More Replacement Energy Needed Results for 2003 Months in Which Derates Occurred in Year Average Rainfall Recorded at Deerhaven (Inches) Actual Rainfall Recorded at Deerhaven in 2003 (Inches) Duration of Derate (hrs) Replacement Energy Necessitated by Derate (MWh) February ,366 March ,592 May ,365 June ,132 July Totals ,879

19 04/09/2006JBM(8) - 19 B&V Study Potential Solutions Improve Pile Management Practices  Reduce Fines Stratification Modify Reclaim Equipment  Water Collecting Gates Install Alternate Reclaim  Above Grade, Dewatering Dozer Trap Install Cover Over Active Reclaim  Intercept Rainfall – GRU’s Preferred Alternative – Estimated Cost $1.5 Million

20 04/09/2006JBM(8) - 20 GRU Economic Analysis Focused on Cost of Replacement Energy Resulting From Unit Derates Recognized That 2003 Experience (12,879 MWh) Was Based on Above Average Rainfall Conservatively Assumed Average Annual Derate of 40 MW for 120 Hours Correlates to 4,800 MWh of Replacement Energy Based on Fuel Forecast (Natural Gas and Coal) – Avoidance of Replacement Energy Yielded and IRR of 13.4%  Satisfied GRU Threshold

21 04/09/2006JBM(8) - 21 Design

22 04/09/2006JBM(8) - 22 Functional Design Criteria Sized to Prevent Rainfall From Impinging on Active Reclaim Area High Enough to Accommodate 1,800 Ton Conical Pile Maximize Area of Coverage Within Space Between Stockout Tower and Perimeter Drainage Swale Support System Cannot Impede Movement of Coal by Mobile Pile Management Equipment Support Structure Should Be Resistant to Contact by Mobile Equipment Must Accommodate Night Time Pile Management Operations

23 04/09/2006JBM(8) - 23 Other Design Criteria Design Life: 30 Years Environment: Subtropical Climate  Hot Summers; Mild Winters Temperature and Humidity:70 F and 90% – Design 115 F and 100% – Extreme Max 10 F – Extreme Min Rainfall: 10-Year Return Period, 24-Hour Event  0.30 Inches Per Hour, 7.2 Inches Total Wind Speed: Per the Florida Building Code (FBC) Seismic: Aa =.05; Av =.05, Soil Profile S-3 Grade: 189 msl Lighting: 5 Footcandles of Illumination, Ability to Control Lighting Level

24 04/09/2006JBM(8) - 24 Design Foundation System 16 – 48 Inch x 55 Foot Drilled Piers Reinforced Concrete Pier Cap  Two Piers Per Cap 2' x 3' Reinforced Concrete Grade Beams Cover Support Structure Concrete Columns Precast Concrete Beams Top of Support Is 25 Feet Above Grade

25 04/09/2006JBM(8) - 25 Cover Support Structure – Concrete Columns and Beams

26 04/09/2006JBM(8) - 26 Cover and Its Structural Framework Initial Concept Was a Geodesic Dome Finally Selected a Rectangular Plan Arrangement to Maximize Coverage Within Allotted Area Arched North to South  Clear Span of 175 Feet 160 in Length East to West and 91 Feet Above Grade at High Point of Arch

27 04/09/2006JBM(8) - 27 Cover and Its Structural Framework Trusses: Fully Triangulated Space Truss Truss Depth Is 8 Feet 7 Trusses With 25 Foot Spacing Fabricated From 8 Inch Wide Flange Aluminum Struts Lateral Stability Provided by 4 Inch Aluminum Tubing Framework Is Bolted Together Skin: Inch Thick Aluminum Skin Is Bolted to Frame Lighting: Interior: 24 HPS Fixtures Attached to Inside of Cover Framework Exterior: 8 HPS Fixtures Attached to Support Structure Each Switch Controls Six Fixtures  Provides Adjustability

28 04/09/2006JBM(8) - 28 Construction

29 04/09/2006JBM(8) - 29 Construction Contracting Approach Engineering – Black & Veatch (Owner’s Engineer) Cover Supply (Detailed Design, Furnish and Erect) – Conservatek General Construction – Yates Construction Construction Management – GRU Overall Schedule Design, Fabrication and Delivery of Cover – 60 days Erection of Cover – 60 days General Construction Original Schedule Was 4 Months Actual Schedule Was 8 Months

30 04/09/2006JBM(8) - 30 Construction Site Preparation For Foundation and Support Structure Construction – Removed 50% of Coal From Active Pile For Erection of Cover Framework and Skin – Rebuild Minimum Coal Base of 12 Feet to Function as Construction Platform Coal Base Filled the 175' x 160' Covered Area Plus 30 to 50 Foot Margin on the East West and South Sides Foundations and Concrete Support Structures Six Week Delay in Mobilizing Drilled Pier Contractor Encountered Unforeseen Subsurface Obstructions Causing Damage to Caisson Installed Inch Diameter Drilled Piers Tied Pairs of Piers Together With Reinforced Concrete Pier Cap Tied Outboard Pier Caps Together With 2 Foot by 3 Foot Grade Beams

31 04/09/2006JBM(8) - 31 Drilled Pier Caisson

32 04/09/2006JBM(8) - 32 Drilled Pier Installation Equipment

33 04/09/2006JBM(8) - 33 Damaged Drilled Pier Caisson

34 04/09/2006JBM(8) - 34 Pier Cap Form Work Foundations and Concrete Support Structures Poured in Place Concrete Columns Were Constructed on the Pier Caps Precast Support Beams Were Placed on Top of the Columns

35 04/09/2006JBM(8) - 35 Concrete Support Structure – Lifting of Precast Beam

36 04/09/2006JBM(8) - 36 Concrete Support Structure – Positioning of Precast Beam

37 04/09/2006JBM(8) - 37 Concrete Support Structure – Setting of Precast Beam

38 04/09/2006JBM(8) - 38 Completed Concrete Support Structure

39 04/09/2006JBM(8) - 39 Erection of Cover and Supporting Structural Framework Unique Design of Cover Necessitated Custom Designed Lifting Towers Framed Two Bays at a Time  Lift  and Proceed. Once Peak Was Reached, Sheeting to the Mid-Point of the Cover Was Accomplished The Process Was Conducted Two Bays at a Time in That Manner Until Complete

40 04/09/2006JBM(8) - 40 Erection Towers and Partially Completed Trusses

41 04/09/2006JBM(8) - 41 Positioning Erection Towers – Partially Completed Trusses

42 04/09/2006JBM(8) - 42 North Side of Trusses Resting on Concrete Support – Skin Partially Installed

43 04/09/2006JBM(8) - 43 Skin Installation About 2/3 Complete – Repositioning South Towers

44 04/09/2006JBM(8) - 44 Skin About 2/3 Complete – Opening for Stockout Chute Almost Complete

45 04/09/2006JBM(8) - 45 View of Erection Towers on South Side and Underside of Trusses

46 04/09/2006JBM(8) - 46 Close-Up View of Erection Towers on South Side

47 04/09/2006JBM(8) - 47 South Side of Cover Being Raised Onto Concrete Supports

48 04/09/2006JBM(8) - 48 Completing Setting of Cover on Concrete Supports

49 04/09/2006JBM(8) - 49 Completed Cover Looking Northwest

50 04/09/2006JBM(8) - 50 Completed Cover Looking Northeast

51 04/09/2006JBM(8) - 51 Completed Cover Looking North From Tripper Gallery

52 04/09/2006JBM(8) - 52 Cost of Cover Preliminary Estimate Was $1,500,000 – Plus or Minus 30% As Bid Costs Totaled $1,718,543 Final Cost Was $1,890,573 Subsurface Difficulties Additional Dewatering Requirements for Foundation Work Extended Schedule

53 04/09/2006JBM(8) - 53 Initial Measurement of Results Rainfall During First 5 Months of Operation Was 60% Above Average No Wet Coal-Related Derates or Replacement Energy Requirements During That Time! Estimated Savings Potentially Accruing From Avoided Replacement Energy Could Have Been $660,000

54 April 9-12, 2006 APPA 2006 Engineering & Operations Technical Conference Sacramento, California Questions?


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