Force Main Valve Applications for

Transcription

1 Force Main Applications for For Additional Information: Jason Chase or Fred Haines or Carl Moser Telephone: www. Harper-Haines.com Presented By Fred Haines of Harper Haines Fluid Control What we ll talk about What we ll talk about What we ll talk about 1

2 Application Problems Application Problems Go with the Flow PUMP SOURCE TREATMENT TRANSFER Lift Stations Same Function Packaged Differently Lift Stations Check Selection WET PIT PUMPING DRY PIT PUMPING 2

3 Application Problems Lift Stations VFD Pumping Creates Varying Flow Rates Pumping Velocity Matters Minimum Pumping Velocity: 4 FPS MAY NOT be 100% open Maximum Pumping Velocity: 15 FPS SHOULD be 100% open Do not exceed this rating Lift Stations - Varying Flow Rates Proper Sizing for Range of Flows Application Problems Fully Open s Do Not Restrict Flow Lift Stations - Varying Flow Rates Partially Open s Effect Headloss Energy Cost is 15% Open Restricted Flow What is Head-loss? ANSWER: The drop in the sum of pressure head, between two points along the path of a flowing fluid, due to causes such as fluid friction (through a valve, or a pipe). Partially Open s Restrict Flow 3

4 Horsepower Expressed as: Flow Coefficient (Cv) Size specific rating OR Resistance Coefficient (K factor) Dimensionless rating ALWAYS CALCULATED AT 100% OPEN Type of (12 ) Port Size Cv K Control 100% Silent Check 100% Swing Check 80% Dual Disc Check 80% Nozzle Check 100% Ball Check 100% Eccentric Plug 80% Surgebuster Check 100% Tilted Disc Check 140% Butterfly 90% Cone 100% 21, Ball 100% 22, Cost versus Energy Consumption Cost versus Energy Consumption High Cost Low Ball K=.03 Tilting Disc Check K=.63 Surge Buster Check K=.80 Energy Consumption Swing Check K=1.58 Booster Pump Control K=5.70 Silent Check K=2.95 High High Cost Low Surge Buster Check K=.80 Energy Consumption Swing Check K=1.58 High Annual Energy Cost Calculations Life Cycle Costs Purchase Costs Installation Costs Maintenance Costs Energy Costs Electrical Cost Per Year ( EC/Y ) = 1.65 x Q x ΔH x Sg x C x U E Where: A = Annual energy costs, dollars per year Q = Flow rate in Gallons Per Minute ΔH = Head Loss of valve (in ft of water) Sg = Specific Gravity of Water C = Cost of electricity, $/kw h U = usage (in percentage) E = Efficiency of pump/motor set 4

5 Annual Energy Cost Calculations Legend of Values Project location: Finish Water Pumping Application Conditions Discharge pumping pressure (in feet of head) Ft 150 Pumping Flow Rate (in GPM) Q 6500 Specific gravity, dimensionless water (water = 1.0) S g 1 Cost of electricity, ($kw-hr) AVG for NJ** C Usage, percent x 100 (1.0 equals 24 hrs per day) U 1.00 Efficiency of pump and motor set (0.80 typical) E 0.80 **Average NJ Commercial Electricity Rate is Courtesy of Annual Energy Cost Calculations Electrical Cost Per Year ( EC/Y ) = 1.65 x Q x ΔH x Sg x C x U E Where: A = Annual energy costs, dollars per year Q = Flow rate in Gallons Per Minute ΔH = Head Loss of valve (in ft of water) Sg = Specific Gravity of Water C = Cost of electricity, $/kw h U = usage (in percentage) E = Efficiency of pump/motor set Baseline Energy Costing Uses Lever & Weight Swing Check s Energy Cost Comparison Using Surgebuster Check Type 1-Year Energy Cost 5-Year Energy Cost 10-Year Energy Cost Baseline $7,766 $38,838 $77,667 Based on 100% Open 14 Type 1-Yr Energy Cost 5-Yr Energy Cost 10-Yr Energy Cost Baseline $7,766 $38,838 $77,667 Surge Buster Style $3,838 $19,193 $38,387 Energy Savings 1-Year $3,928 5-Year $19, Year $39,280 Based on 100% Open 14 Application Problems Lift Stations VFD Pumping and The System Curve Check s close when the system pressure is higher than the pumping pressure 5

6 Lift Stations: Flat vs Steep Pump Curves Orientation Matters Surge Potential + Serviceability Check Slam Severe Impact on Excessive Stress On Components: Seat Disc Shaft Body High Potential for or System Failure Check s and Water Hammer Cause and Effect System Dynamics After Shutdown 1)Residual Forward Flow 2)Moment of Zero Velocity 3)Reverse Flow Pump Cause Of Water Hammer: 1. Check Allows Reverse Flow 2. Reverse Flow Gathers Momentum 3. Check Closes 4. Reverse Momentum Trapped 5. Pressure Surge Results 6. Pipes Stretch Instantaneously 6

7 Tank B creates greater potential for reverse flow and check valve slam than Tank A System Dynamics Tank B Elev.=100ft Tank A Reverse Flow and Water Hammer Every 1 ft/sec of reverse velocity will cause a water hammer (surge) of 50 psi upon check valve closure. Pump Check Elev.=0ft Methods To Prevent Check Slam Close Rapidly Minimize Reverse Flow OR Close Slowly Allow Reverse Flow Slowly Restrict Flow to zero Check Closing Speed Depends on.. Length of Disc Stroke Orientation of Disc in Flow Friction/Inertia of Disc Mechanical Assistance Lever, weight, spring Dampening Devices Air Cushion, Oil Dashpot Rapid Closing Check Short Disc Stroke Low Disc Friction Low Disc Inertia Restrictive Closing Stroke Spring Assistance System Dynamics After Shutdown 1)Residual Forward Flow 2)Moment of Zero Velocity 3)Reverse Flow Pump 7

8 Don t Get Slammed Application Problems Percent Full CV Red Lines = Swing Check 30% Open, 60% Flow Surgebuster 30% Open and 13% of Flow Green Lines = Swing Check 10% Open, 36% of Flow Surgebuster 10% open and 3% of flow Percent Opening Why do s Fail Prematurely? Knife vs Plug vs Gate vs Butterfly Mis- Application Piping Problems Improper Installation Knife gates and plug valves best suited for seating against solids and rags among four listed above for lift station isolation service. Knife Gates Are Designed for Solids Compact Design Plug s Rectangular and Round Ports A design difference that is subject to differing opinions. Surface area at plug. 8

9 2-Way Plug 3-Way Plug Most typical valve configuration, in waste water systems. Usually applied in locations where two valves and associated piping is space limited. 4-Way Plug Center Line of Body Plug Seat End Specialty valve rarely applied, but available. Eccentric Offset Center Line of Seat Clockwise to Close Direct Pressure Reverse Pressure 9

10 Reverse Pressure Application Problems Direct Pressure Don t Introduce Entrained Air Application Problems Sources of Entrained Air 10

11 Three General Sources (of Air) 1. Pipelines are initially filled with Air. 2. There is air in water 2% by volume. 3. Air enters through mechanical equipment. Air in Water is 2% by Volume 1000 feet of pipe contains a slug of air 20 FEET LONG if accumulated in one point 1 mile of pipe contains a slug of air 100 FEET LONG if accumulated in one point. This is true regardless of size of pipe Air Bubbles Raising To High Point, Increasing In Size Entrained Air Problems Typical Flowing Pipeline Highpoint, Without Air Air Collects At High Point Restricted Flow When the large air mass is forced downstream to the next high point, the restriction will cause a velocity change. This change in velocity may cause a pipeline surge. Entrained Air Problems Column Separation at High Points System Shuts Down (Power Failure, Pump Failure, etc.) As Water Drains, A Vacuum Forms at High Point. Draining Vacuum ( Negative Pressure ) Column Separation Entrained Air Problems Columns Rejoining Create Surge The two columns are drawn together by vacuum Rejoining Column Entrained Air Problems Result As columns rejoin, surge may take place causing system damage. Vacuum Damage to Pipeline 11

12 Entrained Air Problems Air Types Vacuum Damage to Water Storage Tank Types of Air s to Remove Entrained Air ARV = Air Release Releases air with pipeline under pressure AVV = Air/Vacuum Releases air only until pipeline is pressurized, breaks vacuum CAV = Combination Air Combines both functions of ARV/AVV Air Types Waste Water Air s Design Differences Clean Water Air Release s (WW-ARV) Air Vacuum (WW-AAV) Combination Air (WW-CAV) Air Types Wastewater Applications WW valve body is expanded to avoid internal fouling. Globe bottom increases float clearance reducing potential for clogging and float lock-up. Air Types Why Automatic Air s? Initial Line Filling Large Amounts of Air Exhaust Pump Start Up Skirted float more receptive to in-rush of media which helps to prevent clogging. Model 48A, for wastewater applications Flow Potential Water Levels 12

13 Air Types Why Automatic Air s? Air Types Why Automatic Air s? Pump Stop Large Amounts of Air Intake Vacuum Protection Pumping Small Amounts of Entrained Air at High Points Flow Flow Flow Waste Water ARV ARV Operation of Air Release s Closed Position Open Position Waste Water AVV Air s Operation of Air / Vacuum s 1 Open: Air exhausted during pipeline fill 3 Open: Air enters during pipeline draining 2 Closed: Pipeline under pressure 13

14 Why An Air / Vacuum Stays Closed Under Pressure Operation: Exhausts air during filling operations & 2 Outlet admits air during draining operations. Note: Does not vent air accumulated during system operation AVV Operation Seat Float Stem Guide Waste Water CAV Alternate Design for Dual Body WW CAV Note Back-washing Accessories Air Types Combination Air s - CAV Single Body Style Dual Body Style Air s Operation Of Combination Air s Open: Air exhausted during pipeline fill Pipeline Under Pressure: Accumulated air continually released Closed: Pipeline under pressure Open: Air enters during pipeline draining Air Sizing and Location 14

15 Air Sizing Parameters Evacuation of Air during pipeline filling not to exceed 1-2 feet per second (FPS) See AWWA Publication M-51 Primary Sizing Premise Free-flow condition in piping: Pipeline rupture As Water Drains, Velocity increases with slope. Air Sizing Parameters Exhaust Air expressed as SCFM (standard cubic feet/minute) Operating differential = 2 PSID for exhausting Use 5 PSID when using surge-check during exhausting Maximum operating differential = 5 PSID for vacuum breaking 7 PSID = Sonic Condition Air Sizing - ARV General Reference Chart Air Sizing - AVV Based on evacuating air on initial fill at a range of 1-2 feet per second (FPS) AVV Rule of Thumb = 1 of valve size per 1-0 Ft of pipe line size Val-Vatic Air Sizing Program Available CAV Sizing ARV and AVV Parameters apply Single Body Sizing more difficult on larger pipe lines Dual Body Combination Units can be custom-built Val-Vatic Air Sizing Program Available 15

16 Example: Air Sizing Report Example: Air Sizing Report Example of Proper Placement Air Location High Points: CAV Long Horizontal Runs: ARV or CAV at 1250 to 2500 ft intervals Long Descents: CAV at 1250 to 2500 ft intervals Air Location Air Location Long Ascents: AAV at 1250 to 2500 ft intervals Decrease in an up slope: AAV Increase in a down slope: CAV Place on or in close proximity to Mechanical Equipment 16

17 Air s at System High Points Air Sizing Air Sizing Program Available At Air Sizing Program Available Online For Additional Information: Fred Haines or Jason Chase or Carl Moser Telephone: www. Harper-Haines.com fhaines@harper-haines.com jchase@harper-haines.com cmoser@harper-haines.com Thank You for Your Time! 17