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Basic compressed air
- 1. Product Line Training Product Line - Industrial Filtration Technology Status: July 2010 01 Basics of Compressed Air C - Generation & Pollution
- 2. 2 Content • Functionality • Type of contruction • Atmospheric Pollution • System Pollution
- 3. 3 Functionality Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible, so the main action of a pump is to pressurize and transport liquids. A compressor is a mechanical device that increases the pressure of a gas by reducing its volume.
- 4. 4 Functionality SO2 NH3 CO CO2 O3 VOCNOX H2O Particle s SO2 NH3 CO CO2 O3 VOC NOX CO2 NH3 NOX VOC VOC Compressed Air Compressor Atmospheric Pressure ≈ 1 bar Compressed Air Pressure ≈ 7 bar Atmospheric Air Compressor
- 5. 5 Content • Functionality • Compressor Types • Atmospheric Pollution • System Pollution
- 6. 6 Compressor Types Positive Displacement Dynamic Reciprocating Rotary Lobe Liquid Ring Screw Vane Scroll Single-Acting Diaphragm Double-Acting Centrifugal Axial Compressor Types Overview
- 7. 7 Compressor Types Dynamic Centrifugal Axial Compressor Types Dynamic Compressors Dynamic compressor depends on a rotating impeller to compress the air. In order to do this efficiently, centrifugal compressors must rotate at higher speeds than the other types of compressors. These types of compressors are designed for higher capacity because flow through the compressor is continuous and oil free by design.
- 8. 8 Compressor Types Compressor Types Positive Displacement Rotary Lobe Liquid Ring Screw Vane Scroll Rotary Compressor Rotary air compressors are positive displacement compressors. The most common rotary air compressor is the single stage helical or spiral lobe oil flooded screw air compressor, consisting of two rotors within a casing where the rotors compress the air internally. There are no valves. These units are basically oil cooled with the oil sealing the internal clearances. Since the cooling takes place right inside the compressor, the working parts never experience extreme operating temperatures making them continious duty compressors.
- 9. 9 Compressor Types Screw Compressor Ca. 50% of all compressors are screw compressors. Existence of two spindle-shaped rotors (screws) which attack each other. Oil-free or Oil lubricated. Functionality 1. phase: The air enters through the opening in the compressor housing. 2. phase: The compressor chamber is closed by the rotation. 3. phase: By reduction of the space, the air is compressed 4. phase: The compressed air enters.
- 10. 10 Compressor Types Screw Compressor – Oil lubricated In case of oil lubricated compressors one part of the oil, determined by the heat and the mechanical pressure is converted into steam. Besides the steam, aerosol consisting of fine droplets and oil in liquid form is released into the air. Production of normal air quality residual oil content about 3 mg / m³ Screw Compressor – Oil free Oil-free screw compressors are called dry running, in which the compression chamber is not lubricated and run the screws couples without contact. Highest precision in manufacturing and production make this compression principle for optimal efficiency. Can be effective over seals to ensure that no oil entering the compression chamber and contaminate the air. A) Dry Compressors: • Production of high pressure air quality • Residual oil content <0.002 mg / m³ • Max. pressure of 1-stage: 3.5 bar • Max. pressure of 2-stage: 10 bar B) Water sprayed Compressors: • Production of high pressure air quality • Residual oil content <0.002 mg / m³ • Max. pressure of 1-stage: 13 bar
- 11. 11 Compressor Types Pressure range Screw Compressor Fluid cooled Dry running Water Oil Single-stage Single-stage Single-stage Single-stage Single-stage Up to 13 bar Up to 160 KW Up to 14 bar Up to 600 KW Up to 20 bar Up to 200 KW Up to 3,5 bar Up to 500 KW Up to 10 bar Up to 1000 KW
- 12. 12 Compressor Types Scroll Compressor Functionality Consisting of a suction chamber, a pressure chamber, a stationary and a rotating screw. Final pressure max. 8bar As between the scroll compressor elements, there is no metal contact, no lubrication of the compression space is needed. Intake air passes through the suction in the suction chamber The rotating screw seals off the suction chamber and pushes the air into the increasingly small pressure chamber. The generated compressed air leaves the compressor via an outlet opening in the center of the screw.
- 13. 13 Compressor Types Compressor Types Positive Displacement Reciprocating Single-Acting Diaphragm Double-Acting Reciprocating Reciprocating air compressors are positive displacement machines. This means that they increase the pressure of the air by reducing its volume, this is accomplished by a piston moving up a cylinder compressing the air above it. Single-stage and two-stage reciprocating compressors are commercially available. Single-stage compressors are generally used for pressures in the range of 70 psi to 150 psi. Two-stage compressors are generally used for higher pressures.
- 14. 14 Compressor Types Reciprocating Existence of a crankcase, crankshaft, connecting rod, cylinder, piston, suction and pressure valve. Oil-free or Oil lubricated Oil-free compressors operate completely without oil. Bearings are greased and encapsulated. 1-2-and multi stage compressor available single-stage double-stage
- 15. 15 Content • Functionality • Compressor Types • Atmospheric Pollution • System Pollution
- 16. 16 Nitrogen 78% Oxygen 21% Other gases 1% Ambient air does not only consist of…. You will also find… Atmospheric Pollution Why is air filtration and treatment needed?
- 18. 18 0,01 0,1 10 1001 10000,001 Viruses Particle Size [ µm ] Vapour, fumes, smoke Dust Mist Spray 10000 Droplets, Grains Bacteria Drifting Sand Gas Molecules Flour Grains of Salt Pollen Dried Milk Spores Pigments Human Hair Soot Cement Dust Tobacco Smoke Coal Dust Oil / Vapour Water Clouds Perceptible under microscope Visually PerceptibleSubmicroscopic Perceptible Atmospheric Pollution Aerosols and Solid Particles
- 19. 19 Pollution Typical concentration range Main source Carbon dioxide (CO2) 600…2000 mg/m³ Internal combustion engines and combustion processes in industry and energy production plants Carbon monoxide (CO) 1…50 mg/m³ Nitrogen oxide (NOX – NO, NO2) 0,01…0,08 mg/m³ Sulphur oxide (SO2) 0,002…0,01 mg/m³ Ammonia (NH3) 0,02…0,05 mg/m³ Agriculture, biogas Ozone (O3) 0,03…0,1 mg/m³ Develops from precursors like NOX or NMVOC (non-methane volatile organic compouns) through photochemical processes Atmospheric Pollution Gaseous Components
- 20. 20 Pollution Typical concentration range Main source VOC (Volatile organic compounds) 4…14 mg/m³ Several industrial processes, vapour from solvents Total emissions of NMVOC (non-methane volatile organic compouns) in the European Union per country Atmospheric Pollution Gaseous Components
- 21. 21 Atmospheric Pollution Water Vapor in Atmospheric Air Atmospheric air always contains a certain amount of water vapor Fog/mist = mass of fine droplets of water in the atmosphere near or in contact with the earth Water vapor is always invisible – do not mistake vapor for fog or mist!
- 22. 22 Atmospheric air is a composition of several gases + water vapor. Percentage portion of each component depends e.g. on the water vapor content Water vapour content at 25°C 70% R.H Atmospheric Pollution Water Vapor in Atmospheric Air
- 23. 23 Atmospheric Pollution Oil – How does the oil get into compressed air? One part of the oil, determined by the heat and the mechanical pressure is converted into steam. Besides the steam, aerosol consisting of fine droplets and oil in liquid form is released into the air. Oil injected screw compressor For 360m³/h (100 l/s) Compressor (37kW) => ± 8 l/s oil Oil carry over ± 3mg/m³ Intake air Compressed air + oil Compressed air 70 to 100ºC Compressed air ambient +10ºC Oil Condensate
- 24. 24 Atmospheric Pollution Oil – Types of oil content Lubricated air compressors introduce three forms of oil contaminant into the compressed air stream: aerosol droplets, vapor and liquid wall flow. By contrast, oil-free compressors introduce no oil contaminants whatsoever
- 25. 25 Atmospheric Pollution Oil – How oil free is the air from oil free compressors? Ambient air aspirated by a compressor already contains some hydrocarbons. The concentration will strongly vary based on the location but the following averages could be representative Average (mg/m3) ISO oil class * Rural < 0.001 1 (0) Sub urban 0.01 1 Light industrial 0.01-0.03 1-2 City 0.01-0.10 2 Industrial area with major hydrocarbon industry 0.1-0.2 2-3 * At the outlet of an oil free compressor it can be estimated that the quality is one class better than those listed above, since the compressor coolers (after the 1st and 2nd stage), dryer and air receiver will also wash out some of these ambient vapours and aerosols and remove them with the condensate.
- 26. 26 Content • Functionality • Type of contruction • Atmospheric Pollution • System Pollution
- 27. 27 SO2 NH3 CO CO2 O3 VOCNOX H2O Particle s SO2 NH3 CO CO2 O3 VOC NOX CO2 NH3 NOX VOC VOC Compressed Air Compressor Atmospheric Concentration 8 x Atmospheric Concentration + H2O AgglomerationAcids + Bases Bacteria Atmospheric Air System Pollution Pollution in Compressed Air Systems
- 28. 28 Corrosion + contamination Material Damage Production downtime High maintenance cost High operating cost (Δp) Production of scrap Invest in new equipment required System Pollution Without Filtration + Treatment…