StocExpo Conference 2013, Antwerp. Dipl.-Ing. Axel Sommer Braunschweiger Flammenfilter GmbH (PROTEGO)

Transcription

1 StocExpo Conference 2013, Antwerp Dipl.-Ing. Axel Sommer Braunschweiger Flammenfilter GmbH (PROTEGO)

2 Where Do My Storage Tank Losses Come From? Storage Tanks Have to Breath

3 Why Overpressure Protection? Pressure rise due to filling of tank (Pump - In) Pressure Rise due to thermal expansion (can be significant with large tank) Pressure rise due to control valve failure (such as tank blanketing regulator) Pressure rise due to atmospheric pressure decrease Pressure rise due to external fire

4 Why Vacuum Protection? Vacuum from tank outflow (Pump - Out) Vacuum from cooling (such as thunderstorm) Vacuum from vapour condensation Vacuum from atmospheric pressure increase

5 Emission Reduction through breathing loss minimization (VDI 3479*) The Function of the P/V Vent is to keep the vapor space closed during variations in the atmospheric pressure and/or temperature decrease in spite of pertinent changes of gas volume and pressure, until that time when a technically admissible low or high pressure is reached Goal: avoid intake of ambient air and discharge of product/air mixture * Forschungsbericht 225 Kohlenwasserstoff Emissionen aus Festdachtanks Vergleich von Berechnungsformeln unter besonderer Berücksichtigung der VDI Richtlinie 3479, Hamburg, February 1985

6 Main influence factor of emission reduction for hydrocarbon vapors a) Upper and lower set pressure of vents (set pressure & set vacuum) b) Temperature difference within the vapor space of the tank c) Hydrocarbon concentration of the hydrocarbon/air mixture in the vapor space (vapor pressure)

7 Set Pressure and Vacuum needs to be influenced MAWP (design pressure)

8 Overall Equation for annual emission of Tank 1 VD f1 m A, a m B a m T, VD f 1 m A, a m B, a = efficiency of p/v-vent (mainly a function of set pressure to full lift) = coating factor = annual emission mass flow of freely vented tank with fixed roof (open nozzle, no conservation vent) = annual emission mass flow of filling

9 Total Breathing Tanks with Open Vent m A, a f A, S c n V n, S d S f A, W c n V n, W d w f A c V n d = saturation ratio (existing concentration to saturation concentration) = saturation concentration of hydrocarbons in vapor space above the liquid surface = mean volume flow = number of summer/winter days per year

10 V n Is calculated from the following equation: V n T n p n p T 1 T p n n p T 1 p T 2 V G 1 t = standard temperature = standard pressure in = atmospheric pressure in mbar m d = mean minimum temperature in K in the vapor space at the morning hours 3 T 2 V G t = mean maximum temperature in K in the vapor space at the midday hours = gas volume above the product, in = reference time, t = 1 d 3 m

11 Finally the average annual emission mass flow from breathing losses amounts to: m A, a f A, S p T M T p n n p T 1, S p T 2, S V G d S f A, W p T M T p n n p T 1, W p T 2, W V G d w T T, S 1, W 1 ; = mean minimum temperature in K in the vapor space in summer or winter T ; T 2, S 2, W = mean maximum temperature in K in the vapor space in summer or winter

12 Calculation Example 1: Fixed Roof Tank freely vented (open nozzle, no pressure vacuum vents) m A, a Resulting Vapor Loss: 15.2 tons/year

13 Total Breathing Fixed Roof Tank with Pressure/Vacuum Vents VD Emission Mass Flow of Total Breathing has to be multiplied by 1 f A, S A, S 1 VD cn ds V f c d V n S n, S( VD) n, S f f A, W A, W c c n n d d W W V V n, W ( VD) n, W V n T p p n 1 2,( VD ) VG p n T1 T 1 operational low pressure p1 absolute atmospheric pressure overpressure% operational overpressure p2 absolute atmospheric pressure overpressure% t The smaller the overpressure % the better the vent

14 Emission Massflow (t/yr) and % of Emission Reduction Calculation Example 2: Fixed Roof Tank with Pressure Vacuum Valves % % % % % 40% 10% 0%

15 lift [mm] - pressure [mbar] Full Lift Pallet - 10% overpressure 15

16 lift [mm] - pressure [mbar] time [s] Vent with 40% overpressure Ventilhub valve lift Tankdruck tank pressure

17 lift [mm] - pressure [mbar] Vent with 100% overpressure Ventilhub valve lift Tankdruck tank pressure time [s]

18 overpressure set pressure mass (opening) mass (reseating) total mass total volume mbar kg kg kg m³ full lift 10% 20 0,08 0,32 0,40 0,5 modulated 40% 14 0,51 0,66 1,17 1,4 modulated 100% 11 2,31 1,08 3,39 4,1

19 TÜV-Certified Flow Test Rig

20 Flow testing of vents according to API 2000/ISO (TÜV Certified Flow Rig) 1. test medium supply (e.g. blower or fan) 2. calibrated flow measurement device 3. test tank 4. calibrated measuring device for pressure and vacuum 5. (pressure and vacuum measurement may be achieved with separate instruments) 6. temperature measuring device 7. barometer - measuring device for atmospheric pressure 8. device to be tested 9. pipe-away if fitted 10. atmospheric temperature and dew point measuring device 11. L = length of connecting pipe (straight pipe nipple) L 9

21 Best Design Practice: Overpressure 100% versus 10% (Considering blow down and leak rate testing) Pset,CV = 3,8 mbarg Pset,N2 = 2,6 mbarg Pset,CV = 14,9 mbarg Pset,N2 = 10,4 mbarg Pset,ERV = 10,0 mbarg Pset,ERV = 18,2 mbarg Example: API 650 Tank with MAWP of 20 mbarg

22 Blow Down needs to be considered when sizing p set d F A F d 4 2 d < D p reseat D F A F D 4 2 p p set reseat

23 Benchmark Report on Vents (leak rate)

24 Why Does A Quality Product Result in Vapor Saving?

25 Leak rate testing according to API 2521 API calls for leak rate testing at 75% of set pressure

26 Leak rate [scfh] 1 Leak rate testing results Groth company A PROTECTOSEAL company B PROTEGO PROTEGO 10% 75 % to set (0.5 oz/sqinch) 75 % to set (0.65 oz/sqinch) Point of full open Tank Pressure oz/sq inch PROTEGO 6" PROTEGO 10% 6"

27 Avoid secondary damage from leaking!

28 Reduce your Explosion Risk from Leaking!

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30 Thank you for your attention Questions?