1.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 GBH Enterprises, Ltd. Engineering Design Guide: GBHE-EDG-MAC-1101 Shaft Couplings for Special Purpose Rotary Machines Process Disclaimer Information 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.

2. 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 Engineering Design Guide: Shaft Couplings for Special Purpose Rotary Machines CONTENTS SECTION 0 INTRODUCTION 1 SCOPE 2 PRELIMINARY COUPLING SELECTION 2.1 Establish Data 2.2 Type Selection SECTION 1 - COUPLING FEATURES BY TYPE 3 GEAR TOOTH COUPLINGS 3.1 Crowning 3.2 Application Envelope 3.3 Oil Lubrication 3.4 Grease Lubrication 3.5 Forces on Machine Bearings 3.6 Balancing 4 DIAPHRAGM COUPLINGS 4.1 Application Envelope 4.2 Forces on Machine 4.3 Natural Axial Frequency of the Spacer 4.4 Stability of Paired Diaphragms 4.5 Balancing 4.6 Contoured Single Diaphragm 4.7 Multiple Laminate Diaphragms 3. 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 ELASTOMERIC ELEMENT COUPLINGS 5.1 Application Envelope 5.2 Elastomer Behavior 5.3 Design Factors in Selection 5.4 Balance 5.5 Alignment 5.6 Materials 6 QUILL SHAFT COUPLINGS 6.1 Stresses 6.2 Forces on Machine Bearings 7 CRITICAL SPEEDS 7.1 Intrinsic Natural Lateral Frequency of Spacer 7.2 Effect on Rotor Dynamic Response 8 LIMITED END FLOAT 9 COUPLING HUB ATTACHMENT 9.1 Attachment by Interference Fit 9.2 Friction Drive Elements 10 ACCESSORIES 10.1 Alignment Measurement 10.2 Torque Measurement 10.3 Guards SECTION THREE - PURCHASE PROCEDURES 4. 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 11 SPECIFICATION 11.1 Supplementary Clauses to API 671, 1st Edition 1979 11.2 Clauses Requiring Purchaser Decisions 12 VENDOR CO-ORDINATION MEETING AGENDA TABLES 1 SERVICE FACTORS 2 COUPLING TYPES AND ATTRIBUTES 3 OPTIMUM RUNNING MISALIGNMENT 4 LUBRICATING COUPLING LIMITS 5 MACHINE CO-ORDINATOR 5. 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 FIGURES 1 PRELIMINARY SELECTION SEQUENCE 2 COUPLING EXPERIENCE 3 COUPLINGS AVAILABLE 4 GEAR COUPLING SELECTION SEQUENCE 5 DEFINITION OF CROWNING 6 APPLICATION ENVELOPE FOR GEAR TYPE COUPLINGS 7 SELECTION OF MATERIALS FOR GEAR COUPLINGS 8 TYPICAL GEAR COUPLING AND PITCH CIRCLE DIAMETER 9 GUIDE TO SPACER MASS 10 GENERAL LIMITS FOR LUBRICATION 11 DIAPHRAGM COUPLING SELECTION SEQUENCE 12 DIAPHRAGM COUPLINGS 13 ELASTOMER ELEMENT COUPLING SELECTION SEQUENCE 14 APPLICATION OF ELASTOMERIC-ELEMENT COUPLINGS 15 CHANGE IN ELASTOMER COMPLIANCE WITH FREQUENCY AT VARIOUS IMPRESSED STEADY LOADS 16 HYDRAULIC FITTING AND REMOVAL OF HUBS 17 PERMISSIBLE TORQUES FOR TAPER RING DRIVERS BIBLIOGRAPHY DOCUMENTS REFERRED TO IN THIS GBHE ENGINEERING DESIGN GUIDE 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 0 INTRODUCTION Couplings between shafts may perform more than one function, thus hydrodynamic couplings can also act as variable-speed devices. Rigid couplings permit no relative movement of the shaft ends. They range from flanges integral with the shaft, to sleeve couplings which permit easy dismantling (exemplified by the oil-injected OK-HB device made by SKF Steel) and for small shafts, by the shrink disc. However, in this GBHE Engineering Design Guide we consider only flexible couplings which permit relative misalignment of the rotating shafts of machines and drivers typically employed in petrochemical plant service. 1 SCOPE This GBHE Engineering Design Guide covers the choice and specification of flexible shaft couplings for transmitting powers above 75 kW between special-purpose rotary machines. The Guide does not cover allied devices exemplified by: (a) Variable-speed couplings. (b) Freewheel couplings. (c) Clutches. (d) Very low speed couplings used for mechanical handling equipment. (e) Torque limiting couplings for reducing the starting load on electric motors. (f) Line shaft couplings for deep well vertical pumps. Additional considerations beyond the scope of this Guide are needed to cover couplings for reciprocating machines or for other machines where large regular cyclic torque fluctuations are encountered. Supplementary clauses to API 671 purchase specification are included. 7. 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 FIGURE 1: PRELIMINARY SELECTION SEQUENCE 8. 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 2 PRELIMINARY COUPLING SELECTION 2.1 Establish Data (a) Maximum power transmitted. (b) Maximum speed of operation (not necessarily at maximum power). (c) Service factor from Table 1. TABLE 1: SERVICE FACTORS (abstract from API.613. Ed.3) Enter the Experience/Availability Charts (Figures 2 and 3) to obtain the preliminary choice of coupling. 9. 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 2.2 Type Selection Consider the following topics for type selection: FIGURE 2: COUPLING EXPERIENCE 10. 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 FIGURE 3: COUPLINGS AVAILABLE 11. 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 12. 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 (a) High Power On large machine trains, a flexible coupling duty may lie outside the operational envelope of Figures 2 and 3, thus leading to re-arrangement of the train to split the power flow. Alternatively the machine shaft ends may be coupled rigidly or by a quill shaft. (b) High Transient Torque Electric motor drivers are inherently capable of high transient torques. When the drive is through a gearbox, it is current practice to insert a torsionally compliant coupling, typically an elastomer coupling, between an electric motor and the adjacent gearbox where: (1) The driver is an induction motor with a switched start device such as the Korndorfer System. (2) The driver is a synchronous motor with salient poles. (3) The speed-increasing gearbox is an epiyclic type. Note: Elastomer-element couplings need not be the first choice for: (i) Direct-coupled motors. (ii) Parallel-shaft gearboxes used in conjunction with induction motors. (c) High Speed Gear tooth couplings have been the first choice for high speed machines defined by: 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 (d) Low Forces or Moments applied to Shafts Where a minimal forces on thrust and radial bearings are required then diaphragm couplings are the first choice. As an example, the following loads are representative for a coupling transmitting 15 MW at 108 r/s with parallel offset of 1.0 mm per meter of spacer length: Moments: Gear coupling tooth pitch dia 230 mm 7270 N m Contoured diaphragm dia 420 mm 124 N m Continuous rig diaphragm dia 350 mm 28 N m Axial Forces: Gear 30 kN Diaphragm 1 kN Note: If the gear coupling is worn, the value will significantly increase. (e) Drive Continuity Coupling element failure may disconnect the drive. Such disconnection may cause an immediate hazard. Review instrumentation required to alert the operators on failure. Auxiliary back-up coupling mechanisms may be required. (f) Regular Lubrication Unacceptable Select a diaphragm coupling or an elastomer element coupling. (g) Zero Backlash Drives Where torque reversals may occur and zero deadband transmission is required, for governors or other controllers, then select a diaphragm coupling. 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 (h) High Offset Specify a spacer coupling. Note that long spacers are sometimes termed Cardan Shafts. The spacer length for a gear coupling is determined by the maximum angular misalignment, which is given by the limit on tooth sliding speed (see Clause 3.2(b)). As a first estimate take this maximum misalignment as: 15. 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 16. 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 SECTION 1 - COUPLING FEATURES BY TYPE 3 GEAR TOOTH COUPLINGS The sequence of selection is shown in Figure 4. 3.1 Crowning Crowning the teeth is necessary to avoid edge loading due to misalignment [6]; it is illustrated in Figure 5. Do not confuse crowning with edge relief; the latter applies over only a small part of the face width to eliminate tooth end effects on ordinary gears. Note that crowning is sometimes called barreling. FIGURE 5: DEFINITION OF CROWNING A crowned gear tooth coupling has an optimum running misalignment, from the point of view of lubrication and coefficient of friction, as shown in the following table [12]. 17. 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 TABLE 3: OPTIMUM RUNNING MISALIGNMENT 18. 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 FIGURE 6: APPLICATION ENVELOPE FOR GEAR TYPE COUPLINGS 19. 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 3.2 Application Envelope The limits shown in Figure 6 are derived from the following empirical design criteria: (a) Resistance to Fretting Dudley estimated the fretting wear limits for involutes splines [1]. Following Woodley [7], his results have been re-presented in Figure 7. FIGURE 7: SELECTION OF MATERIALS FOR GEAR COUPLINGS 20. 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 (b) Boylan limit on tooth sliding speed [2]. For typical turbine and compressor couplings, V should be less than 0.12 m/s for continuous running. Above this value severe wear of a form known as 'worm tracking' occurs [6] unless the lubricant viscosity is high enough to ensure an oil film thickness above 0.5 m. Low speed (< 15 r/s) couplings with high crowning and high viscosity lubricant have operated with sliding speeds up to 0.40 m/s. (c) Contact Stress Limit The contact stress is indirectly assessed by the tooth contact load factor (analogous to Lloyds K factor for gears), obtained from: 21. 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 (d) Conti-Barbaran Limit Conti-Barbaran [3] developed a criterion defined as: Figures 8 and 9 give some guidance on spacer mass (hub with male teeth) [6]. Elastic deformation of the coupling muff by the combination of speed and residual unbalance leads to increased load on the teeth. The criterion was developed for couplings typical of marine practice for which B should exceed 10. For higher hardness teeth, lower minimum values are permissible; given by: 22. 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 FIGURE 8: TYPICAL GEAR COUPLING AND PITCH CIRCLE DIAMETER 23. 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 FIGURE 9: GUIDE TO SPACER MASS 3.3 Oil Lubrication Typical oil flow needs at each end of a coupling [4] are shown in Figure 10. With short male teeth driving, tooth inclination is favorable for generating hydrodynamic oil pressure. At the other end of a symmetrical coupling the opposite applies. If the misalignment at one end of the coupling is very small, local fretting can occur. Oil viscosity is an important parameter. 24. 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 Coupling wear reduces with increasing oil viscosity up to a 40 cSt at 100C (Viscosity Grade VG 680) [5]. The minimum operating viscosity is 50 cP, equivalent to VG 46 at 40C or VG 32 at 30C. Hot high-viscosity grade oil is better than cool low-viscosity grade oil that has the same operating viscosity. Coupling lock-up can be caused by fine solids (< 15 m) centrifuged out of the oil. Inbreathing at bearing labyrinths is one source of contamination. The return of bearing housing vents to an oil drain header reduces this. 3.4 Grease Lubrication A widely quoted limit is a pitch-line velocity of 40 m/s but the centrifugal acceleration at the pitch line is a more relevant parameter than velocity. 25. 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 The type of oscillating motion that occurs at the tooth contacts is best lubricated by a fluid, but most manufacturers recommend grease as it is easier to retain in the coupling than oil. In the centrifugal field grease tends to separate into oil, which escapes from the enclosure by creep, and a hard soap-rich phase which is ineffective as a lubricant. Experience with lubricated couplings gives the following limits: Re-lubrication implies that the coupling has to be split to allow the old grease to be removed completely. These re-lubrication periods make grease-packed couplings unsuitable for machines in Reliability Class 1 and 2 as defined in GBHE-EDG-MAC-1101. An alternative to grease lubrication is to use a semi-fluid soap thickened polyglycol, such as Shell Tivela Compound A. The soap content of Tivela Compound A is lower than that of a grease so that the material remains a fluid. The polyglycols are more effective as lubricants than mineral oils. Experience with Shell Tivela Compound A is that it provides satisfactory lubrication without changing for two years, thus making lubricant-filled couplings suitable for Reliability Class 2 operation. Lubricant retention is ESSENTIAL. 26. 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 3.5 Forces on Machine Bearings A misalignment of up to 2 mm/m is common [7]. The direction of the load is at an angle to the direction of offset, typically trailing 40 in the direction of rotation. 27. 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 3.6 Balancing Dynamic balance of the complete coupling requires tip centering or, (where the tooth flanks define the position of the spacer under load) locked in torque. Tip centering is likely to be required [7] if: If the complete coupling cannot be balanced with locked in torque or tip centering, the spacer should be balanced when centered on its outside diameter. Tip clearance in operation depends on growth of the female coupling half, distortion due to shaft/hub interference and the radial component of contact force. Tip centered components may not be interchangeable. 4 DIAPHRAGM COUPLING The selection sequence is shown in Figure 11. This type of coupling sub-divides into two classes: (a) Single contoured diaphragm (Type I in Figure 12). (b) Multiple diaphragm (laminate) either spoked or continuous ring, transmitting torque by shear forces or tension in alternate sections respectively. Continuous ring couplings (Type III in Figure 12) are smaller in diameter than the others for the same torque, they also continue to drive on diaphragm failure by interference between the diaphragm fixings. They permit higher misalignments. 28. 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 FIGURE 11: DIAPHRAGM COUPLING SELECTION SEQUENCE 4.1 Application Envelope See Figures 2 and 3. 29. 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 4.2 Forces on Machine (a) All diaphragm couplings should be installed so that at operating conditions they are not axially offset. The axial load is then insignificant. (b) Radial forces due to parallel misalignment are then: 4.3 Natural Axial Frequency of the Spacer Any axial natural frequency band (due to a non-linear axial spring rate) shall be avoided. The low end of the band is given by: 30. 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 4.4 Stability of Paired Diaphragms Couplings are produced commercially with an enhanced misalignment tolerance by using paired diaphragms. Paired diaphragms are forbidden for use at either end of a spacer coupling, unless an unlubricated centering bearing is provided, as they provide no radial location and the spacer mass centre will move to an eccentric position, over-stressing the diaphragms at high speeds. 4.5 Balancing The hubs are balanced individually. The diaphragm unit is balanced while mounted between both hubs. 4.6 Contoured Single Diaphragm This is illustrated as Type I in Figure 12. The diaphragm is contoured to decrease in thickness from hub to rim. Key parameters are:- (a) Stresses Stresses should be less than 50% of the fatigue limit at 107 cycles. Coarse surface finish leads to scatter in fatigue test results, resulting in an undefined endurance limit. Axial deflection leads to high stresses at the hub and centrifugal forces are highest at the hub. The torque load gives only small incremental stresses. Angular misalignment leads to similar stress levels for a tapered or parallel diaphragm provided that: For constant shear stress, the thickness is inversely proportional to the radius squared. Radial corrugation can allow more axial deflection. 31. 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 (b) Cooling The disc in this type of coupling is of necessity a large diameter in order to gain the required flexibility. High windage losses due to the large diameter can result in high temperatures: Some installations have been reported to need an oil jet or air blast for cooling. (c) Materials The material selection is typically AISI 4340 alloy steel, vacuum melted and cross-rolled to obtain isotropic properties. Heat treatment is applied to obtain a tensile strength of about 1200 MN/m2. Resin coating may be required to prevent corrosion. This coating also permits rapid checking for localized mechanical damage. 32. 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 FIG 12: DIAPHRAGM COUPLINGS 33. 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 4.7 Multiple Laminate Diaphragms Type II (Figure 12), typified by the Metastream M series, transmits power by subjecting the laminate to shear forces due to the differing diameters of the driving and driven bolt circles. In this type, the flexible element is built up from a number of thin steel laminates in a single pack, clamped by bolts. The laminates are 0.5 mm to 0.25 mm thick. Experience has shown that AISI 310 material is satisfactory, being resistant to corrosion and suitable for stamping in volume manufacture. The individual laminates are machined and finished ground together in a pack of the size intended in the application. After this stage the packs are never broken down or shuffled. The packs and precision-machined clamping washers are held together by bolting carefully torqued to about 75% of the clamp bolt proof load. This procedure drastically reduces the probability of fretting failure in the pack. Type III (Figure 12), is typified by the Metastream T series or Thomas SN and 51, 52 series. Torque is transmitted only by tensile loads in half of the ring. The section of the stressed element may be shaped to obtain continuity of strain energy, producing a coupling better able to withstand shock loads. Four bolt ring type couplings do not transmit steady torque and velocity when angularly misaligned; ideally 5 to 8 bolts should be used. Type IV (Figure 12), is a variation of Type III, having separate links. It is extremely difficult to match the links during assembly; thus load sharing is imperfect and the life expectancy erratic. This type should be avoided. (a) Application Envelope The use of these couplings is unrestricted up to the boundary given by: Above this boundary, a vibration analysis should always be done. 34. 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 (b) Natural Frequencies For the ring type (Figure 12, Type III), use as a rough guide: For spoked and ring types, when the slack is taken up, the axial spring rate is non-linear. Thus the natural frequency depends on the amplitude, increasing as the excitation increases. Current practice is to avoid operation at a running speed above the coupling natural frequency unless the margin exceeds 30%. Operation below the speed corresponding to the natural frequency for infinitesimal amplitudes is acceptable when the margin exceeds 6%. The axial natural frequencies of Metastream spacer and coupling elements are typically within the range 65 to 95 Hz; consequently such couplings should not be used above 60 r/s without specific review of possible excitation. Note that this only refers to resonance of the spacer. 35. 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 FIGURE 13: ELASTOMER ELEMENT COUPLING SELECTION SEQUENCE 36. 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 ELASTOMERIC ELEMENT COUPLINGS For the selection sequence of the Elastomer Element Coupling, see Figure 13. 5.1 Application Envelope The limits applicable to commercially available couplings are shown in Figure 14. It is possible to operate up to 80 r/s in the small sizes, the limit being set by the precision of manufacture and the dynamic response of the elastomer element. Above the 'normal' limit line couplings may be made individually. Consequently accuracy depends on operator skill. It has been necessary to specify on the following manufacturing accuracy for drives up to 25 r/s. (a) All cylindrical surfaces to be concentric to 0.1 mm radially and 1 in 10,000 maximum angular deviation relative to the axis. (b) All radial surfaces to be flat to 0.1 mm and equi-spaced to 1 in 10,000. (c) Surface finish, where there is contact with elastomeric blocks, to be better than 3.2 m Ra. 5.2 Elastomer Behavior The non-linear elastic modulus and the intrinsic hysteresis of elastomers tend to suppress torsional resonance. The fundamental torsional mode of the machine set should occur at less than 20% of normal running speed under normal load conditions and should not exceed 60% under maximum acceleration. The properties of elastomers are not well defined nor are they time-stable. The elastomer dynamic compliance decreases with increasing frequency [14], see Figure 15. Hardness has a major effect. The design of inserts should be based on a minimum Shore Hardness of 60, though for on-site modifications a hardness value of 45 is permissible. 37. 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 The shape of the inserts relative to the shape of the cavity in the body of the coupling has an effect on compliance and the movement under centrifugal load affects balance. When operating close to the speed limit line a wedge shape insert is needed to minimize the average stress by ensuring a close fit in the coupling body at the periphery. For unprotected machines in cold climates check the 'glass-point' temperature of the rubbers. The minimum operating temperature is then 48C above this temperature. 38. 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 FIGURE 14: APPLICATION OF ELASTOMERIC-ELEMENT COUPLINGS 39. 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 5.3 Design Factors in Selection Couplings should be selected on the basis of being capable of continuous operation at the unfactored nominal electric motor peak torque. The coupling design should permit the renewal of elastomer inserts without disturbing the driver or driven shafts or the coupling hubs. Cardan shaft type couplings should use non-lubricated centering bearings. Coupling types which rely on placing the rubber in shear should be avoided since progressive failure is possible with resulting loss of drive continuity. 5.4 Balance Insert sets are supplied in match weighed sets, normally within 0.5% band. It is essential that the batch is clearly identified and is not mixed in any way with a different batch. Inserts should be changed only as complete sets. Silicone oil is used to ease assembly. 5.5 Alignment Experience on Holset WB couplings shows that residual misalignment at start-up will be locked-in under the heavy load peculiar to electric motor drivers. It is necessary to specify to the machine manufacturers that:- (a) Cold parallel misalignment shall not exceed 0.02 mm. (b) Differential displacement from cold to hot operating conditions shall be limited to 1/500 of the effective spacer length or 0.20 mm whichever is smaller. These requirements constrain the machine maker's choice of support; it may be necessary to use centre-line mounting. 40. 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 5.6 Materials Coupling bodies should be made from carbon steel or nodular cast iron. Grey cast iron should be prohibited. Resin laminate material used for limit stops should mate with 13% chrome steel hardened to 380-420 HV. 41. 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 42. 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 QUILL SHAFT COUPLINGS 6.1 Stresses The resultant stresses, constant and cyclic, in a quill shaft should not exceed 50% of those that permit a life in excess of 107 cycles for the particular material. For solid uniform section circular steel shafts, the maximum stresses are: 43. 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 44. 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 SECTION TWO - EFFECTS ON COUPLED MACHINES 7 CRITICAL SPEEDS 7.1 Intrinsic Natural Lateral Frequency of Spacer A long coupling spacer should have a natural frequency in bending at least 50% above running speed. Neglecting friction at the points of articulation, i.e. assuming pin jointed ends [4]: 7.2 Effect on Rotor Dynamic Response Where the ratio of central mass (including shaft between bearings) to shaft end mass (including shaft overhang) is less than 0.25 and the ratio of overhang to span is less than 0.3 the reduction in the first critical speed will be less than 10%. The second critical speed can be dramatically affected by overhung mass. This can be assessed by mathematically modeling the rotor (e.g. Current computer program are ROMAX and BIRD). 45. 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 LIMITED END FLOAT Under driving torque, both gear and elastomer block couplings require a significant force to cause relative axial displacement of the shaft ends. This is likely to be greater than the axial magnetic centering forces of a motor thus, as the shafts expand thermally, the motor rotor will be displaced. On run down the torque is reduced but the magnetic force is absent so the running position is held until the coupling comes to rest. On cooling in the absence of driving torque the coupling is likely to permit axial movement, thus increasing the displacement for the next start. Current practice is to specify a limited end-float feature such that the motor rotor is held off its bump stops. Diaphragm couplings normally provide sufficient axial restraint for sleeve bearing motors during run up and run down and while reaching operating alignment. Where the axial movement is large or the master state is misplaced significant axial forces can be generated while the motor rotor is off its magnetic centre. 9 COUPLING HUB ATTACHMENT Coupling hubs integral with the shaft are preferred but frequently cannot economically be provided. 9.1 Attachment by Interference Fit The preferred method of attaching coupling hubs to the shaft is by interference fit, without keys. See Figure 16. Installation can be by hydraulic expansion of the hub bore together with hydraulic control of axial position [13]. Expansion pressures of 1500-4000 bar and pushing pressures of 500-1000 bar are typical. Robust stops to prevent ejection of the hub during hydraulic removal are necessary [15]. Use of threaded components for assembly in poor conditions can lead to shaft end damage or failure to fit the hub. Thermal expansion demands that there is no delay or pause in fitting; temperatures in excess of 250C should not be used. 46. 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 Precise final axial location of the hub and specified pull up need to be achieved where a taper surface is employed. 9.2 Friction Drive Elements For smaller sizes of coupling (