Breaking The Cycle Of Pump Repairs

TutorialOf the numerous process centrifugal pumps undergoing repair right this very minute, an estimated 90% have failed randomly before. Some have run just fine until the very first repair two or three years after startup, and were never quite the same since after the first repair. Other pumps failed frequently or randomly— perhaps once a year--from the time they were originally commissioned. That brings up such questions as: Could it be we don’t really know why many process pumps are failing? Could it be we just don’t give pumps the attention they deserve? Is it because everybody’s priorities are elsewhere? Or are there perhaps elusive failure reasons, i.e., factors overlooked by all parties? Fortunately, improvement is both possible and cost-justified. Allowing repeat failures on process pumps rarely makes economic sense. Simple benefit-to-cost or life cycle analyses will easily demonstrate that the pursuit of remedial action greatly benefits users

Lubrication Delivery Advances For Pumps And Motor Drivers

TutorialA ranking order is found in the Eschmann-Hasbargen-Weigand text “Ball and Roller Bearings” (ISBN 0-471-26283-8) for oil and grease-lubed bearings. The author re-assesses this ranking with input derived from the collective experience of a “Rotating Machinery Network.” It is found that, unless plant-wide oil mist systems are justified, the listing in Table 1 is encouraging; it recommends oil-air for rolling element bearings. Details on all oil and grease application methods referenced in ISBN 0-471- 26283-8 and ISBN 978-1-4822-2864-9 are explained. Particular emphasis is given to (a) jet oil spray, (b) oil mist, now successfully used on approximately 26,000 electric motors and 130,000 process pumps world-wide, (c) shield orientation in typical grease-lubricated electric motor bearings and (d) good experience with PFPE-based (perfluoropolyether) greases in fully-sealed motor bearings. The PFPE experience completely up-ends prior notions regarding grease-filled (sealed) bearings

Storage Preservation Of Machinery.

LecturePg. 35-46Storage preservation of machinery makes economic sense fur as yet uncommissioned as well as temporarily deactivated ("mothballed") machinery. Storage preservation herein is divided into three main elements: turbomachinery rotor storage and preservation, preservation of inactive machinery by conventional coating or liquid fill methods, and preservation of inactive machinery by nitrogen or oil mist purge application. Guidelines are given on desirable properties or available preservatives. Typical cost data are presented for oil mist purge installations which have been effectively used in equipment storage facilities and on entire process units in the U. S. Gulf Coast area

Breaking The Cycle Of Pump Repairs

Tutoria

Using Modified Acoustic Emission Techniques For Machinery Condition Surveillance

LecturePg. 139-158.Acoustic emission is the release of high frequency sound energy in a material under strain. It is the result of microscopic changes in material structure and is associated with deformation and defect growth. Until about 1973, acoustic emission technology was primarily employed in the non-destructive testing of such structures as pipelines, heat exchangers, storage tanks, pressure vessels, and coolant circuits of nuclear reactor plants. However, the applicability of this technique to the detection of defects in rotating equipment bearings was recognized and the results of prototype testing were published in 1973. These tests led to the development of a plant-wide, computerized acoustic incipient failure detection (IFD) system which was leased from a major aerospace contractor in 1975 and evaluated until early 1977. In late 1977, advanced, second generation IFD systems were employed. These systems incorporate features which greatly enhance component reliability and usefulness to plant operators. Automated acoustic emission sensing has proven to be indispensable for dependable surveillance of machinery condition. Design concepts and field experience with advanced, second generation acoustic IFD systems are described and many actual incipient failure warning events illustrated in detail

Recent Experience With Large Liquid Injected Rotary Screw Process Gas Compressors.

LecturePg. 43-56Advances in manufacturing techniques and design enhancements for such components as shaft seals have made it possible for liquid flooded rotary screw compressors to achieve availability, reliability, and overall performance thought impossible 10 years ago. With some machines operating continuously for over 30000 hr, and installed driving power levels exceeding 7000 hp per compressor train, process engineers and machinery specialists may have to reassess older notions of the application range for this close cousin of the modem turbocompressor. Specific details on construction features and design parameters are given for large rotary screw process machines which can clearly outperform turbocompressors and reciprocating process compressors in selected gas compression services. Two application examples are given, together with shortcut estimating procedures on the performance, initial installed cost, probable maintenance cost, and projected long term operating cost of large state-of-the-art rotary screw machines

Vacuum Distillation Methods For Lube Oils Increase Turbomachinery Reliability.

LecturePg. 41-50The lube oils in self-contained reservoirs for turbomachinery in hydrocarbon processing plants are subject to contamination and deterioration from airborne dust, component debris, system corrosion, heat, and water. Oil supplies associated with certain gas compression sealing systems are further exposed to potential dilution with lighter hydrocarbons, and gaseous dilutants such as H₂S. Excess water and acquired hydrocarbon constituents which adversely influence the viscosity and other characteristics of turbomachinery lube oils must be removed periodically, if machinery distress is to be avoided. As part of a determined effort to maintain the reliability of critically important turbomachinery, a major petrochemical complex has implemented a lube oil quality assurance program. Vacuum distillation equipment is used for oil purification, and periodic analysis of 36 reservoirs is employed to quantify lube oil condition. A major refinery in the same geographic area is developing a program with similar goals. The relevant experience accrued at both facilities is described. What is required to have consistently good results and to obtain the maximum economic benefits is illustrated. This can be achieved by evaluating and selecting an appropriately designed vacuum oil purifier and following up by implementing a rigorous analysis program

POWER2008-60068 MECHANICAL SEAL EFFICIENCY CONSIDERATIONS FOR PUMPS IN UTILITIES ECONOMICS OF SEALS VS. PACKING, AND SAVINGS WITH BEST AVAILABLE SEAL FLUSH ARRANGEMENTS

ABSTRACT Applicable industrial standards for centrifugal pumps endorse several different sealing options as "best practice." However, the overall acceptance of best practice techniques seems slow and is linked to the fact that sealing devices account for only a small fraction of the energy consumed by pumps. Yet, regardless of perception, significant energy conservation has been achieved by thoughtful sealing practices, as this paper will show. It will highlight case studies that provide guidance on issues of increasing technical and societal concerns relating to fluid emissions. Special attention will be directed to barrier fluid circulation devices used in dual mechanical seal arrangements as described by API-682 (Ref.1), a Standard widely used in the oil refining and petrochemical industries. The applicability of these ciculation devices to the Power Industry will be explained. Comparisons of three of the most widely used conventional integral flow induction/pumping ring devices will be made and the results of extensive testing presented. The paper and presentation also quantifies the value of advanced sealing technologies for pumps and highlights configurational differences between the newer and the more traditional (older) devices. Without exception, international utilities and power producers know that both energy and maintenance expenditures are affected by availability and reliability considerations relating to power generators and their turbine drivers. But feed water pumps and cooling water issues play their part as well. Consequently, a measure of attention has been given to "other big ticket items", such as cooling tower losses and the like. However, there is compelling evidence that additional, less prominent or less obvious opportunities exist and that these can no longer be overlooked. Pump sealing falls into that category, although sealing devices and seal cooling account for only a small fraction of the energy consumed by pumps. In can be readily shown that significant energy savings have been achieved by thoughtful sealing practices. The general narrative and the implications conveyed by our case studies give visibility to the issues and provide guidance to the user. ENERGY EFFICIENCY DESERVES ATTENTION By way of introduction, we should accept the premise that pumps require a sealing device to prevent liquid from escaping where the driving shaft enters the pump casing As to traditional pump designs in the power industries, recently developed sealing technology can provide utilities and related power producers with further efficiency improvements. The key to those improvements lies in carefully selecting the most appropriate means of seal cooling. Keep in mind also that fluid machines in all industry sectors consume energy and contribute to CO 2 emissions (Ref. 2). Accordingly, a few quantitative highlights will shed light on experience-based findings relating to emissions. Initially and in the first half of the 20 th Century, the area of shaft penetration (called stuffing box) was fitted with compression packing. This will be considered later, in conjunction with a relevant case history. After the 1950's and in the industrialized world, the traditional gland packing shown i

A Self-Consistent Solution to the Nuclear Many-Body Problem at Finite Temperature

The properties of symmetric nuclear matter are investigated within the Green's functions approach. We have implemented an iterative procedure allowing for a self-consistent evaluation of the single-particle and two-particle propagators. The in-medium scattering equation is solved for a realistic (non-separable) nucleon-nucleon interaction including both particle-particle and hole-hole propagation. The corresponding two-particle propagator is constructed explicitely from the single-particle spectral functions. Results are obtained for finite temperatures and an extrapolation to T=0 is presented.Comment: 11 pages 5 figure

Modeling autosomal recessive cutis laxa type 1C in mice reveals distinct functions for Ltbp-4 isoforms

Recent studies have revealed an important role for LTBP-4 in elastogenesis. Its mutational inactivation in humans causes autosomal recessive cutis laxa type 1C (ARCL1C), which is a severe disorder caused by defects of the elastic fiber network. Although the human gene involved in ARCL1C has been discovered based on similar elastic fiber abnormalities exhibited by mice lacking the short Ltbp-4 isoform (Ltbp4S(-/-)), the murine phenotype does not replicate ARCL1C. We therefore inactivated both Ltbp-4 isoforms in the mouse germline to model ARCL1C. Comparative analysis of Ltbp4S(-/-) and Ltbp4-null (Ltbp4(-/-)) mice identified Ltbp-4L as an important factor for elastogenesis and postnatal survival, and showed that it has distinct tissue expression patterns and specific molecular functions. We identified fibulin-4 as a previously unknown interaction partner of both Ltbp-4 isoforms and demonstrated that at least Ltbp-4L expression is essential for incorporation of fibulin-4 into the extracellular matrix (ECM). Overall, our results contribute to the current understanding of elastogenesis and provide an animal model of ARCL1C.Peer reviewe