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ALMiG Adsorption Dryers: Advanced Drying Solutions for Compressed Air Systems

Explore the various models and advantages of ALMiG adsorption dryers for achieving a pressure dew point as low as -70°C. Learn about the adsorption drying process, cold and warm regeneration methods, and how these dryers provide constant low-pressure dew points.

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ALMiG Adsorption Dryers: Advanced Drying Solutions for Compressed Air Systems

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  1. 2 Contents • ALMiG adsorption dryers • General function of adsorption dryer • Overview of ALM adsorption dryers • ALM adsorption dryers • ALM-CCD • ALM-CD • ALM-WD • Special models • Adsorption dryer design • ALM-HOC

  2. Classification of moisture reg. DIN ISO 8573-1:2010 Area foradsorptiondrying

  3. ALMiGdrying procedures Adsorption Condensation Refrigeration dryer(Pressure Dew Point ≥ +3°C) Adsorption dryer(PDP < 3°C to -70°C)

  4. If cooling to +3°C (corresponding to a residual moisture level of 5.95 g/m3) is not sufficient, e.g. • pipelines above ground level (cold in winter) • outdoor receivers / consumers • the process requires drier air • etc. • the • adsorption dryer • drying system must be used.

  5. Adsorption drying The adsorption principle: The water vapour contained in the compressed air is bound to the surface of a granulate-shaped drying agent (adsorbate) by the forces of adhesion. Depending on the drying agent used, pressure dew points of down to -70°C can be attained. Note: Unlike the refrigeration drying process, the compressed air is not cooled. The adsorption process itself requires no energy; energy only has to be used to regeneratethe adsorbate, i.e. to remove the moisture collected. Since the regeneration process requires a certain amount of time, an adsorption dryer always consists of two receivers, one of which is always operating while the other is regenerating or 'drying'.

  6. General function of adsorption dryer An adsorption dryer consists of 2 receivers: One receiver is used to dry the compressed air (1). The drying agent is regenerated in the other receiver, i.e. moisture is now expelled (2). 1 2 The system switches between the two depending on loading or at defined intervals. • 2 possible forms of regeneration: • cold regeneration • warm regeneration Reduction in moisture to ISO class 1-3, Pressure dew point: ≥ -70°C/ -20°C

  7. Adsorption Drying in general An adsorption dryer consists of 2 receivers: One receiver is used to dry the compressed air (1). Second receiver is used for the regeneration of desiccant, which means reduction of moisture (2). 1 2 There will be switched between the receiver regarding time intervals or charge load.. • 2 possibilities of regeneration: • cold regeneration • warm regeneration Humidity reduced to ISO class 1-3, DTP: ≥ -70°C/ -20°C

  8. Types of adsorption drying Warm regeneration Regeneration with supply of heat Cold regeneration Regeneration with a partial flow of dry compressed air Internal warm regeneration With compressor heat (HOC) Caution 10 – 20 % of the valuable compressed air is used as purge / regenerating air. Regeneration with a partial flow of dry compressed air and internal, electric heating Regeneration through use of compressor heat, no additional energy supply • Collection of moisture • on outer surface only • Short adsorption time of 4 – 10 min • Collection of moisture on the • internal and external surface • Long adsorption time of 4 – 10 h

  9. Overview of ALM adsorption dryers ALM-CCD Cold regeneration - compact series ALM-CD Cold regeneration ALM-HOC Heat of Compression ALM-WD Warm regeneration

  10. ALM-CCD (Compact Cold Desiccant) Key data: Cold-regenerated adsorption dryer Volume flow: 9 – 45 m³/h Pressure dew point: -40°C; -70°C Operating pressure: 3 – 10 bar Ambient temperature: 5 – 50°C • Advantages: • Compact and space-saving / wall mounting possible • Variable pressure dew point, can be set using microswitch • 10 min. cycle for -40°C • 4 min. cycle for -70℃ • Low maintenance costs • Simple installation / operation • Constant pressure dew point

  11. ALM-CD (Cold Desiccant) • Key data: • Cold-regenerated adsorption dryer • Volume flow: 100 – 9400 m³/h • Pressure dew point: -20°C; -40°C; - 70°C • Operating pressure: 4 – 10 bar (higher pressures on request) • Ambient temperature: 5 – 50℃ • Advantages: • Constant low pressure dew point • Low investment, low maintenance costs • Simple installation / operation • EMS Energy Management System (optional) • Virtually maintenance-free process valves

  12. ALM- cold regeneration in detail Phase Phase 1 2 Compressed air outlet Compressed air outlet Drying at operating pressure Drying at operating pressure Pressure increase Regeneration outlet Compressed air inlet Compressed air inlet • Once the adsorbent in the left-hand receiver is saturated and regeneration is taking place in the right-hand receiver, they change over. • The pressure in the right-hand receiver is first balanced using system compressed air. • The adsorbent is protected from major changes in pressure • The adsorbent life is extended The left-hand receiver adsorbs the compressed air while the right-hand one is busy with regeneration.

  13. ALM- cold regeneration in detail Phase Phase Compressed air outlet Compressed air outlet 4 3 Drying at operating pressure Drying at operating pressure Buildup of pressure Regeneration outlet Compressed air inlet Compressed air inlet As soon as the right-hand receiver has built up pressure, they change over and the right-hand one starts adsorbing. Regeneration takes place in the left-hand receiver. Once the adsorbent in the right-hand receiver is now saturated and regeneration is taking place in the left-hand receiver, they change back again. The pressure in the left-hand receiver is then balanced using system compressed air.

  14. Adsorption dryer design Vnom: Nominal volume flow at dryer inlet. To get the volume flow of dried compressed air, please subtract 15% from that calculation because of regeneration air. The detailed design will be done project-wise.

  15. ALM-WD (warm desiccant) Key data: Warm-regenerated adsorption dryer Volume flow: 245 – 4280 m³/h Pressure dew point: -40°C Operating pressure: 4 – 16 bar Ambient temperature: 5 – 50°C Purge air / cooling air share just 2.5% Regeneration by heating elements inside the receivers.

  16. Advantages: • Ideal positioning of heating elements in drying bed • Direct heat transfer to the adsorbent • Optimum use of regenerative energy • No fan / no external blower • No contact with the ambient air and therefore no ingress of liquid molecules / particles / etc. • Longer drying agent life • No additional noise from fans / blowers • Simple installation/operation • Low maintenance costs • EMS Energy Management System (optional) Ideal distribution of heat thanks to optimum positioning of heating elements

  17. ALM- warm regeneration in detail Drying4,5 hours Cooling1,25 hours Drying Heating & regeneration 3 hours max. • As soon as the moisture is removed from the dry granulate, the heating elements are switched off • The purge air from the right-hand receiver is used to cool the granulate • The compressed air flows through the right-hand receiver, the adsorption agent dries the compressed air • Desorption through internal heating takes place in the left-hand receiver • A small partial flow of the air dried in the right-hand receiver is pressure-relieved and used to dry the moist granulate in the left-hand receiver. • The moist air is blown outside via a silencer

  18. ALM- warm regeneration in detail Drying Stand-by and pressure balancing Drying Drying • The valve on the purge air output is closed, pressure in the left-hand receiver is balanced until operating pressure is reached in the two receivers • The compressed air in the right-hand receiver continues to be dried • Once operating pressure has been reached in the left-hand receiver, compressed air is dried in both receivers in parallel for a short time

  19. ALM- warm regeneration in detail Drying Expansion Heating &regeneration Drying • The valve on the purge air outlet in the right-hand receiver is opened and operating pressure reduced • Dying takes place in the left-hand receiver • 1 complete adsorption and desorption process is now complete. • The next function process starts but the receiver functionalities are now reversed

  20. Adsorption dryer design To get the volume flow of dried compressed air, please subtract 2,5% from that calculation because of regeneration air. The detailed design will be done project-wise.

  21. Take care when designing adsorption dryers: Compressor Refrigeration dryer 10 m3/min of dry compressed air is fed into the pipework system. 10 m3/min 10 m3/min Adsorption dryerwarmregeneration Close to 9.75 m3/min of dry compressed air is fed into the pipework system. 9.75 m3/min 10 m3/min Adsorption dryercoldregeneration 10-20% compressed air loss through cold regeneration  Only around 8.5 m3/h of dry compressed air is fed into the pipework system. 10 m3/min 8.5 m3/min

  22. ALM-HOC (heat of compression) • In ouroil-freecompressionsystems • oil-free DUPLEXX screwcompressoror • DYNAMIC turboseries • thecompressedaircanbedriedusingheatfromthecompressor. Isthecompressionheat large enough, dryingcanbedonewithout an additional supplyofenergy.

  23. ALM-HOC (heat of compression) Key data: Pressure dew point: down to -40°C Volume flow: 800 – 6000 m³/h Operating pressure: 5 – 10 bar Adsorption temperature: 35°C Hot air inlet temp.: max. 230°C Cooling water temperature: max. 32℃ Ambient temperature: 5 – 40℃ Compression temperature: 140 – 180°C • Requirements for use: • Oil-free compression • Compressor with integrated aftercooler • Hot air connection • Cold air connection

  24. Advantages: • Dry compressed air is produced immediately after starting up / starting back up • Low pressure losses of just 0.2 to 0.3 bar under design conditions • Partial load of up to 20% of capacity with guaranteed pressure dew point • Intermittent compressor operation is possible at guaranteed pressure dew point • Low maintenance costs • Replacing the adsorption agent costs around 15-20% of the system price • The drying agent can be replaced a bit at a time • Only standard DIN/ISO components commonly found on the market are used • Systems can be increased to any size (scale-up) • Large volume of adsorption agent, therefore: • one regeneration cycle in 2 to 4 hours • Long adsorption agent life (up to 10 years) • The high-temperature zinc coating on the pipes and separator offers max. corrosion protection, especially for the inner areas at particular risk • High reliability by: - Compact cooler design - Safe condensate drain - Protected cables and pipes

  25. Function Desorption phase The hot partial flow of compressed air coming from the compressor flows over the hot air inlet K1 and the 4/2-way tap cock HK2 (connection 3/2) into the desorbing adsorption receiver B2. The moisture absorbed by the drying agent evaporates and passes to the cooler along with the partial flow of desorption air via the 4/2-way tap cock HK1 (connection 2/1) and fitting K3. Here the compressed air is cooled to the adsorption inlet temperature required. The condensate collected during cooling is discharged from the compressed air system via the downstream separator. The cooled partial flow of desorption air then flows behind the butterfly valve KS1 into the partial flow of cold air coming from the compressor. The partial air flow required for regeneration can be adjusted by hand using the butterfly valve KS1. The volume flow now again corresponds to the compressor's delivery volume. The entire compressed air flow is fed via HK1 (connection 3/4) into the adsorption receiver B1 intended for adsorption. The flows pass from the bottom up through the drying agent bed during adsorption. During this passage, the drying agent absorbs the moisture. The dry compressed air passes to the points of consumption via the 4/2-way tap cock HK2 (connection 4/1) and system outlet. The desorption process decreases the amount of moisture in the drying agent. As the moisture level falls, the outlet temperature of the desorption air flow increases. Desorption is complete when the temperature of the desorption air flow on the adsorber outlet side (here B2) has reached the temperature required by the procedure.

  26. Function Cooling phase In order to prevent peaks in temperature and dew point after changing over, the heat stored in the drying agent is cooled by the partial flow of cold compressed air after the desorption phase. The cold partial flow of compressed air coming from the compressor passes to the heated adsorption bed via the valve K4 and the 4/2-way tap cock HK1 (connection 1/2). During this flow, the cold partial flow of compressed air absorbs the heat stored in the drying agent. The partial flow of compressed air heated by the drying agent flows to the cooler where it is cooled down to the adsorption temperature. The cooled partial flow of cooling air then flows behind the butterfly valve KS1 into the partial flow of cold air coming from the compressor. The volume flow now again corresponds to the compressor's delivery volume. The entire compressed air flow is fed via the 4/2-way tap cock HK1 (connection 3/4) into the adsorption receiver B1 intended for adsorption. The flows pass from the bottom up through the drying agent bed during adsorption. During this passage, the drying agent absorbs the moisture. The dry compressed air passes to the points of consumption via the 4/2-way tap cock HK2 (connection 4/1) and system outlet.

  27. Function Stand-by Stand-by If the adsorption phase is being monitored and terminated by a control system dependent on dew point (optional), the length of the standby phase depends on the loading state of the adsorption receiver (here B1). The process of changing over is only initiated once the drying agent breakthrough capacity (increase in pressure dew point) is reached. If the system is being operated in "time-dependent changeover" mode, the process of changing over is initiated after the set cycle time. Process of changing over Once the standby phase is complete, adsorption on the regenerated receiver (here B2) is moved into the corresponding position by reversing the 4/2-way tap cocks HK1 and HK2. The receiver saturated with moisture B1 is now in the desorption phase, while the adsorption receiver B2 starts to dry the compressed air.

  28. HOC vs. rotary dryer Heat of compression (HOC) Rotary dryer • Dry compressed air is produced immediately after starting up and starting back up • Dry compressed air is only produced • after a stabilisation period • Pressure losses of 0.2 to 0.3 bar under • design conditions - Pressure losses of between 0.2 and 0.6 bar • Poorly suited to partial load operation • (Pressure dew point increases) • Partial load of up to 20% of capacity at guaranteed pressure dew point • Intermittent compressor operation at • guaranteed pressure dew point • Intermittent operation causes • fluctuations in pressure dew point • Pressure dew points of down to -20°C under normal operating conditions. PDP is not stable for changing volume flows. - Stable pressure dew points of down to -40°C

  29. HOC vs. rotary dryer Heat of compression (HOC) Rotary dryer - High maintenance costs: - Low maintenance costs: • Changing the adsorption agent costs • around 50% of the system price • Changing the adsorption agent costs • around 15-20% of the system price • The drying agent can be replaced at bit at a time • The drum can only be replaced in one piece • Use of manufacturer-specific components • Only standard DIN/ISO components • commonly found on the market are used - Large volume of adsorption agent, therefore: - Low volume of adsorption agent, therefore: • One regeneration cycle in 2 to 4 hours • Up to six regeneration cycles per hour • Long adsorption agent life iii(up to 10 years) • Short adsorption drum life (4-5 years) • Systems can be increased to any size • (scale-up) - Scale-up not possible

  30. Design HOC-Dryer HOC-Dryer must bedesignedindividuallyforeachapplication. • Followinginformationandparametersarenecessary: • Numberofcompressionstages • Existanceof a coldor a hotairoutlet • Size ofvolumeflow • Operating pressureandtemperatureofthecompressedairbefore last stage (after intermediate cooler) • Outlet temperaturebefore aftercooler(„hot“) • Outlet temperaturebehind aftercooler („cold“) • Final pressure • Temperatureofcoolingwater • Suctionconditions (climaticvalues) • Suctionpressure (heightabovesealevel) • Ambienttemperature • Necessarypressuredewpoint (summer / winter)

  31. ALMiG Kompressoren GmbH Adolf-Ehmann-Strasse 2 • 73257 Köngen Sales tel. no.: +49 (0)7024 9614-240 Sales e-mail address: sales@almig.de www.almig.de

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