Colorado School of Mines Pollution Prevention

1. Colorado School of MinesPollution Prevention Fugitive Emissions

5. Fugitive Emissions • Unintentional releases, such as those due to leaking equipment, are known as fugitive emissions • Can originate at any place where equipment leaks may occur • Can also arise from evaporation of hazardous compounds from open topped tanks

6. Fugitive Emissions Sources Pumps and Valves Tanks Measurement Calculation Prevention

7. Sources of Fugitive Emissions

8. Sources of Fugitive EmissionsPumps and Valves • 70% of process plant fugitive emissions are from pumps and valves • Measurement of fugitive emissions will require some level of knowledge of pumps and valves

9. Sources of Fugitive EmissionsPump Packing

10. Sources of Fugitive EmissionsCentrifugal Pump

11. Sources of Fugitive EmissionsPump and Motor Assembly

12. Sources of Fugitive EmissionsPumps and Flanges

13. Sources of Fugitive EmissionsGate Valve

14. Sources of Fugitive EmissionsGlobe Valve

15. Sources of Fugitive EmissionsGate Valve

16. Sources of Fugitive EmissionsGlobe Valve

17. SourcesCheck Valve

18. Sources: Butterfly Valves

19. Sources of Fugitive EmissionsFlanges

20. Sources of Fugitive EmissionsFlanges

21. Piping Systems • One line diagrams • Valves • Pumps • Pipes

22. Tanks

23. Tanks

24. Tanks

25. TanksFugitive Emissions • Tanks are designed to reduce fugitive emissions • Floating roof tanks are typically used for very large diameter tanks where a fixed roof construction becomes expensive to support and for products where vapor emissions become an issue

26. Fugitive Emissions from Storage Tanks There are six basic tank designs • Fixed roof • vertical or horizontal • least expensive • least acceptable for storing liquids • emission are caused by changes in • temperature • pressure • liquid level

27. Fugitive Emissions from Storage Tanks • External floating roof • open-topped cylindrical steel shell • steel plate roof that floats on the surface of the liquid • emission limited to evaporation losses from • an imperfect rim seal system • fittings in the floating deck • any exposed liquid on the tank wall when liquid is withdrawn and the roof lowers • Domed external floating roof • similar to internal floating roof tank • existing floated roof tank retrofitted with a fixed roof to block winds and minimize evaporative loses

28. External Floating Roof Tanks

29. Fugitive Emissions from Storage Tanks • Internal floating roof • permanent fixed roof with a floating roof inside • evaporative losses from • deck fittings • non-welded deck seams • annular space between floating deck and the wall

30. Fugitive Emissions from Storage Tanks • Variable vapor space • expandable vapor reservoirs to accommodate volume fluctuations due to: • temperature • barometric pressure changes • uses a flexible diaphragm membrane to provide expandable volume • losses are limited to: • tank filling times when vapor displaced by liquid exceeds tank’s storage capacity

31. Measuring Fugitive EmissionsInstruments • Portable gas detector • Catalytic bead • Non-dispersive infrared • Photo-ionization detectors • Combustion analyzers • Standard GC with flame ionization detector is most commonly used

32. Measuring Fugitive EmissionsApproach • Average emission factor approach • Screening ranges approach • EPA correlation approach • Unit-specific correlation approach

33. Measuring Fugitive Emissions • What factors can impact fugitive emission measurement?

34. Average Emission Factor Approach ETOC = TOC emission rate from a component (kg/hr) FA = applicable average emission factor for the component (kg/hr) WFTOC = average mass fraction of TOC in the stream serviced by the component

35. Screening Ranges Approach • Leak/ No-leak approach • more exact than the average emissions approach • relies on screening data from the facility, rather than on industry wide averages

36. EPA Correlation Approach • Predicts mass emission rates as a function of screening values for a particular equipment type • Total fugitive emissions = sum of the emissions associated with each of the screening values • Default-zero leak rate is the mass emission rate associated with a screening value of zero

37. EPA Correlation Approach

38. Unit-Specific Correlation Approach • Most exact, but most expensive method • Screening values and corresponding mass emissions data are collected for a statistically significant number of units • A minimum number of leak rate measurements and screening value pairs must be obtained to develop the correlations

39. Controlling Fugitive Emissions • Modifying or replacing existing equipment • Implementing a leak detection and repair (LDAR) program

40. Equipment Modification

41. Equipment ModificationMagnetic Drive Pump

42. LDAR Programs • Designed to identify pieces of equipment that are emitting sufficient amounts of material to warrant reduction of emissions through repair • Best applied to equipment types that can be repaired on-line or to equipment for which equipment modification is not suitable

43. Emissions Estimation from Storage Tanks LT = total losses, kg/yr LS = standing storage losses, kg/yr LW = working losses, kg/yr The standing storage losses are due to breathing of the vapors above the liquid in the storage tank MV = vapor molecular weight R = universal gas constant, mm Hg-L/EK-mol PVA = vapor pressure at daily average liquid surface temperature, TLA = daily average liquid surface temperature, EK VV = vapor space volume, m3 WV = vapor density, kg/m3 KE = vapor space expansion factor, dimensionless KS = vented space saturation factor, dimensionless 365 = days/year )TV = daily temperature range, EK )PV = daily pressure range, )PB = breather vent pressure setting range, PA = atmospheric pressure,

44. Emissions Estimation from Storage Tanks HVO = vapor space outage, ft = height of a cylinder of tank diameter, D, whose volume is equivalent to the vapor space volume of the tank Q = annual net throughput (tank capacity (bbl) times annual turnover rate), bbl/yr KN = turnover factor, dimensionless for turnovers > 36/year, KN = (180 + N)/6N for turnovers # 36, KN = 1 where N = number of tank volume turnovers per year KP = working loss product factor, dimensionless for crude oils = 0.75 for all other liquids = 1.0

45. Fugitive Emissions from Waste, Treatment and Disposal I = important S = secondary N = negligible or not applicable Surface Wastewater treatment plants Land Pathway impoundments Aerated Non-aerated treatment Landfill Volatilization I I I I I Biodegradation I I I I S Photodecomp. S N N N N Hydrolysis S S S N N Oxidation/red’n N N N N N Adsorption N S S N N Hydroxyl radical N N N N N