Forsthoffer's Rotating Equipment Handbooks Vol 4: Auxiliary Systems • ISBN: 1856174700 • Pub. Date: August 2005 • Publisher: Elsevier Science & Technology Books Preface This Series has evolved from my personal experience over the last 40 years with the design, selection, testing, start-up and condition monitoring of Rotating Equipment. Most of the concept figures were originally written on a blackboard or whiteboard during a training session and on a spare piece of paper or I beam during a start-up or a problem solving plant visit. My entire career has been devoted to this interesting and important field. Then and now more than ever, the cost of rotating equipment downtime can severely limit revenue and profits. A large process unit today can produce daily revenues in excess of US$5 million. And yet, the Operators, Millwrights and Engineers responsible for the safety and reliability of this equipment have not been afforded the opportunity to learn the design basis for this equipment in practical terms. I have also observed in the last ten years or so, that the number of experienced personnel in this field is diminishing rapidly. Therefore the series objective is to present, in User friendly (easy to access), practical terms (using familiar analogies), the key facts concerning rotating equipment design basis, operation, maintenance, installation and condition monitoring to enable the reader (Engineer, Operator and Millwright) to: • Understand the effect of process and environmental changes on equipment operation, maintenance and reliability • Condition Monitor equipment on a component basis to optimize up-time, mean time between failure (MTBF) and mean time to repair (MTTR) • Select, audit and test the Equipment that will produce highest safety and reliability in the field for the lowest life cycle cost. The hope is that the knowledge contained in this series will enable XI Preface WBBBMMBHWMHHBMHBWI^ Plant Operations, Maintenance and Engineering Personnel to easily access the material that will allow them to present their recommenda tions to management to solve existing costly problems and produce new projects of optimum reliability. This volume, Auxiliary Systems, deals with the function and application of each major system type (lubrication, control, liquid and gas seal, cooling, buffer gas and pump flush), component selection and design of - reservoirs, pump systems, control valves and instrumentation, coolers/ filters and transfer valves, design audits and troubleshooting of systems and components, preventive maintenance, key reliability indicators, system condition monitoring and much more. XII Acknowledgements This series is a result of interactions with literally thousands of dedicated engineers, machinists, operators, vendors, contractors and students who have been an integral part of my career. I consider myself very fortunate to have been associated with the best of the best mentors, business associates and dear friends throughout my career. Most especially, in chronological order Dick Salzmann, Bob Aimone, Merle Crane, Walt Neibel, the late Murray Rost, Mike Sweeney and Jimmy Trice. Bob, Merle, Murray and Mike have contributed specifically to the material in this series while Dick, Walt and Jimmy have tactfully kept me on track when necessary. Special thanks to all of the global machinery vendors who have allowed me to use their material for my training manuals and now this publication. Last but certainly not least; my career would not have been possible without the support, encouragement and assistance from my wife Doris and our children Jennifer, Brian, Eric, Michael and Dara. A special additional note of thanks to Michael who helped assemble the material, and hopefully learned some in doing so, since he has elected to pursue a career in rotating machinery. XV About the author Bill Forsthoffer began his life-time career in rotating machinery in 1962 with De Laval Turbine Inc. as a summer trainee. After obtaining a Bachelor of Arts degree in Mathematics and Bachelor of Science degree in Mechanical Engineering, during which time he worked for De Laval part time in the Test, Compressor and Steam Turbine Departments, he joined De Laval fiill time in the Compressor Engineering Department in 1968. He was responsible for all phases of centrifugal compressor component and auxiliary design and also made many site visits to provide field engineering assistance for start up and problem resolution. Bill joined Mobil Oil Corporate Engineering in 1974 and was responsible for all aspects of rotating equipment specification, technical procurement, design audits, test, field construction, commissioning, start-up and troubleshooting. After 15 years at Mobil, Bill founded his own consulting company in 1990 and has provided rotating equipment consulting services to over 100 companies. Services include: project reliability assurance, training (over 7,000 people trained) and troubleshooting. Bill is active in the industry as President of Forsthoffer Associates Inc., frequently writes articles for Turbo Machinery International Magazine and conducts many site specific and public workshops each year. He can be contacted at [email protected] XVII Table of Contents 1 - Introduction and overview, Pages 1-8 2 - Auxiliary system types and functions, Pages 9-22 3 - The reasons for inherently low auxiliary system reliability, Pages 23-30 4 - The development of an auxiliary system, Pages 31-50 5 - Auxiliary system component design—the pumping unit, Pages 51-96 6 - Component design control valves and instrumentation, Pages 97-119 7 - Component design coolers, filters and transfer valves, Pages 121-134 8 - Auxiliary system function summary, Pages 135-144 9 - Auxiliary system specifications, Pages 145-152 10 - System design audit and factory testing, Pages 153-181 11 - Assuring and maintaining auxiliary system reliability, Pages 183-208 12 - Lubrication system overview and types, Pages 209-221 13 - Compressor seal system overview and types, Pages 223-243 14 - Seal system component design and preventive maintenance, Pages 245-256 15 - Seal system—the contaminated seal oil drain system, Pages 257-269 16 - Dry gas seal systems, Pages 271-289 17 - Combined lube and seal systems, Pages 291-300 18 - Separate lube and seal systems, Pages 301-312 19 - Buffer gas system overview, Pages 313-324 20 - Buffer gas system operation and preventive maintenance, Pages 325-335 21 - Pump flush system overview, Pages 337-348 22 - Pump single seal flush system, Pages 349-357 23 - Pump tandem and double seal flush system, Pages 359-364 24 - Conversion to metric system, Pages 365-376 •-u'i;-4| Introduction and 1 overview / B Introduction Objectives The auxiliary system The types of auxiliary systems Introduction In this book, I will confine attention to those systems that support critical rotating equipment units. I.E., large turbo-compressors, centrifijgal pumps, their transmission devices and drivers. This book is intended for anyone who is or will be responsible for critical equipment selection, reliability, operation or maintenance. The importance of critical or special purpose rotating equipment, in attaining the owner's objectives of maximum process revenue cannot be overemphasized. Virtually all large process systems today rely on critical rotating equipment units to meet production quotas. Critical or special purpose units directly impact product revenue as opposed to non-critical or general purpose equipment which does not. Daily process unit product revenue losses can range from $100,000 to over $2,000,000 U.S. dollars (or $4,000-$83,000 per hour) for each day a critical unit is out of operation. In addition, the high speeds, pressures, temperatures and toxic fluids associated with critical equipment operation, present a potential safety problem. As a result, critical equipment safety and reliability is of utmost importance. Reliability is defined as the percentage of time the unit is producing product per year. Today, critical equipment usually is the dynamic or turbo type as opposed to positive displacement (usually 1 Auxiliary Systems Figure 1.1 Typical multi-stage, radially-split centrifugal compressor (Courtesy of Mannesmann Demag) reciprocating) equipment that was used in the past. As process units became larger, the high maintenance, slow speed and large 'footprint' positive displacement type was replaced by the lower maintenance, smaller footprint (more product per unit equipment area) and higher speed turbo type. This approach was true for both the driven equipment and the driver. A typical turbo-compressor and steam Figure 1.2 Multistage condensing extraction turbine (Courtesy of General Electric Company) Introduction and Overview Exhaust Steam Inlet Steam Figure 1.3 Steam turbine and compressor schematic turbine used for critical service is shown in Figures 1.1 and 1.2. Since critical equipment is always designed to meet specific process requirements, it is 'custom designed'. Faced with the exposure to large product revenue losses, many companies have instituted a critical equipment assurance program. The program's objective is to attain the highest possible critical equipment on line reliability through the effective specification, procurement manufacture, testing, installation, operating and preventive maintenance of the equipment. The success or failure of such a program really depends upon the definition of the 'equipment'. Figure 1.3 is a schematic of the turbo-compressor and driver shown in Figures 1.1 and 1.2. In the past, when positive displacement equipment was utilized, this picture was a true representation. That is, the sealing, lubrication, control and cooling systems were essentially self contained in the critical equipment itself Today however, a representation of our turbo-compressor unit is shown in Figure 1.4. The supporting systems are large, remote, complicated, usually inaccessible and not always understood fiinctionally. Before proceeding fiirther, let's define a 'system'. A system is a set of connected things or parts that work together. Refer again to Figure 1.1 and locate the rotor, bearings and seals. Now refer to Figure 1.4 and identify the supporting systems associated with each item. The Rotor - though not the subject of this course, the turbo- compressor product throughout depends on the rotor. It's operating point is determined by the equilibrium between rotor energy available and the energy required to move a given product quantity through both the suction and discharge system. The point here is that product revenue can be negated not only by a compressor failure but by the upset or failure of any of the numerous components in the process system. Therefore, one