1. GBH Enterprises, Ltd.Engineering Design Guide: GBHE-EDG-MAC-1536Hydrogen CompressorsInformation contained in this publication or as otherwise supplied to Users is believed to be accurate and correct at time of going to press, and is given in good faith, but it is for the User to satisfy itself of the suitability of the information for its own particular purpose. GBHE gives no warranty as to the fitness of this information for any particular purpose and any implied warranty or condition (statutory or otherwise) is excluded except to the extent that exclusion is prevented by law. GBHE accepts no liability resulting from reliance on this information. Freedom under Patent, Copyright and Designs cannot be assumed.Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com

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Engineering Design Guide:Hydrogen CompressorsCONTENTSSECTION1SCOPE22PHYSICAL PROPERTIES22.1 2.23Data for Pure Hydrogen Influence of Impurities23.1Hydrogen from Electrolytic Cells33.24MATERIALS OF CONSTRUCTIONPure Hydrogen334.1Pulsation34.25DESIGNBypass3TESTING OR COMMISSIONING RECIPROCATING COMPRESSORS46LUBRICATION47LAYOUT48REFERENCES4Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 3. FIGURES 1MOLLIER CHART - HYDROGEN2COMPRESSIBILITY CHART3NELSON DIAGRAM4WATER CONTENT IN HYDROGEN FOR OIL-LUBRICATED COMPRESSORS AS GRAMM/M2 SWEPT CYLINDER AREARefinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 4. 1SCOPEThis Engineering Design Guide describes those requirements for a compressor centered system which arise from the duty with hydrogen.2PHYSICAL PROPERTIES2.1Data for Pure Hydrogen Molecular Weight2Critical values:TK = 33.25K PK = 12.95 bar(Reference I)VK = 0.0323 m3/kg Cp = 14.23 kJ/kg/o C at 10CSpeed of sound:1286 m/sec @ OCCp/C v = 1.41(Reference 2)A Mollier chart is given in Figure I, a compressibility chart on Figure 2. (Ref 3)2.2Influence of ImpuritiesThe density of the hydrogen is so low that small quantities of impurities cause large increases in density, e.g. the density is doubled by 7.5% N2 in hydrogen. The consequent effects are: (a)Reciprocating Compressors The increase in density leads to increases in pulsation and also increased loads on the valves. Both pulsation levels and valve velocities should be checked when operating on the heaviest gas to be handled.Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 5. (b)Centrifugal and Axial Compressors Increase in the density of the gas handled results in a nearly equal increase in pressure ratio. For this reason the use of centrifugal compressors on hydrogen rich gases subject to impurities is not recommended.3MATERIALS OF CONSTRUCTIONAt temperatures normally encountered with compressors all ferrous materials are suitable. At temperatures above 200C and elevated pressures, however, special steels should be used. A Nelson diagram is given in Figure 3 (Reference 4). Non-metallic materials are not affected at moderate pressures. Non-ferrous materials are not attacked by pure hydrogen below 200C.3.1Hydrogen from Electrolytic CellsHydrogen from electrolytic cells is: (a)Saturated with water(b)Contains other impurities (Hg, etc) particularly mercury.If mercury is carried over, then aluminium and aluminium alloys should not be used. All non-metallic materials are suitable at moderate pressures.3.2Pure HydrogenThere is limited evidence that extremely pure hydrogen - purer than 99.9% causes the speed of fracture propagation to be increased by several magnitudes. The presence of a small amount of impurity (oil, water or other gases) eliminates this effect. The first indication of this phenomenon with reciprocating compressors is expected to be frequent valve failures as valves are the highest stressed parts within the compressor cylinder (Reference 5 & 6).Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 6. 4DESIGN4.1PulsationThe basic pulse (d p = CV) is low in systems handling hydrogen because of the low density - in spite of the higher speed of sound. However, the volume required for a given attenuation is large; pulsation dampers for hydrogen are therefore expensive. By keeping velocities low in the pipework pulsation dampers can be avoided. A relationship between line pressure cylinder arrangement and permissible velocities is given by:where V P C K4.2= = = =velocity in m/sec in the pipe pressure in bar speed of sound in m/sec 0.4 for single cylinder, single acting machines, and 0.2 for single cylinder, double acting machinesBypassWhen hydrogen is expanded from high pressures (above 110 bar) it warms up in the process. However, the effect is small (see Figure. 3).5TESTING OR COMMISSIONING RECIPROCATING COMPRESSORSReciprocating hydrogen compressors are usually tested on air. Under these conditions the velocity in the valves will be excessive and leading to excessive pressure drop. Either valves of a different kind are to be used or other precautions taken.Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 7. 6LUBRICATIONOn lubricated machines the oil film will tend to be starved of oxygen. To replenish the oxide film on the cylinder wall it is necessary to either operate the machine periodically on air or to add small quantities of water to the hydrogen or to the oil. (see Figure 4.) This can be done by adding a small percentage of wet hydrogen either from another source or by passing some hydrogen through a saturator.7LAYOUTThe minimum area classification for machines operating on hydrogen is Division 2 Class B. Machines should preferably be installed in buildings with sufficient ventilation to prevent the build-up of an explosive mixture under normal operation. They also ensure that any accidental release of hydrogen is quickly removed from the building.Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 8. REFERENCES 1Comprehensive Inorganic Chemistry: Bailar, J C, Emeleus, H J, Sir Ronald Nyholm, Trotman-Dickenson, A F Tables of Physical & Chemical Constants2Kaye and Laby3F Frohlich Kolben Verdichter4API 941: Steel for Hydrogen Service at Elevated Temperatures and Pressures in Petrochemical Refineries and Plants5Walter, R J and Chandler, W T: 'Cyclic Crack Growth in ASHE SA 105 Grade 2 Steel in High Pressure Hydrogen at Ambient Temperature' printed in 'Effect of Hydrogen on Behavior of Metals', published by AIME 1976, p 2736Nelson, H G: 'Hydrogen Induced Slow Crack Growth under Cyclic Loading' Ibid p 602Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 9. FIGURE 1- MOLLIER CHART HYDROGENRefinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 10. FIGURE 2- COMPRESSIBILITY CHARTRefinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 11. FIGURE 3- NELSON DIAGRAMRefinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 12. FIGURE 4 - WATER CONTENT IN HYDROGEN FOR OIL-LUBRICATED COMPRESSORS AS GRAM/M2 SWEPT CYLINDER AREARefinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 13. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com 14. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com