Optimizing compressor packing designs by predicting rod temperatures.

LectureThe pressure packing is a critical component of every reciprocating compressor. High wear leads to increased process gas leakage rates which can result in a compressor shutdown. Excessive leakage can even cause fugitive emissions if the emission control system is not set up for high leakage levels. These fugitive emissions can cause environmental concerns, safety issues in case of hazardous gases and it can lead to reliability problems if the crank case is contaminated with process gas. High pressure applications, non-lube machines or abrasive environments are especially prone to high wear rates and increased packing leakage rates. Current packing engineering standards rely on rule of thumb methods and selection tables. This lecture presents a method to maximize the packing run time by optimizing the performance determining parameters of the packing. By predicting the rod temperature distribution, the performance of different packing layouts can be compared and relative run time prediction can be given. The lecture describes the model details, discusses the heat transfer correlation assumptions and deducts general packing design guidelines based on the model results. Several packing optimizations have been performed using this approach and two case studies are discussed in this lecture

A Novel Method for Evaluating Sideload Compressor Thermodynamic Performance

LectureA method has been developed that allows reasonably accurate sectional performance evaluation of sideload compressors based upon only external measurements available from the streams entering and exiting the compressor casing at the respective nozzles. Estimated sectional thermodynamic performance has historically been limited to acceptance testing where temporary temperature measurement instrumentation has been inserted into the flow path between sections. Accurate longer term evaluation and monitoring of compressor performance once installed and operating has not been possible. While overall, multi-section thermodynamic performance may be obtained by the heat balance method as defined in ASME PTC 10, individual section behavior has not been attainable with the existing procedures. The method logic and equation development is presented for a two-section sideload compressor but can be extended to compressors with additional sections (typically three or four) through the application of some additional logic and calculations. A number of example cases derived from data sheet predicted information and a PTC 10 Type 2 test are included to demonstrate the potential accuracy of the proposed method

Excessive Axial Load on Main Oil Line Pump Thrust Bearing, Measurement and Control

Case StudyThis case study describes the deployment of an axial load measurement and control solution for centrifugal pumps experiencing high bearing temperatures on the Non-Drive End (NDE). Through the real-time measurement of the axial load on-skid, informed and successful control of the balance line pressure was performed. Thus, the effect of the balance piston was increased and the overall load on the bearing was reduced by ~75% allowing the pumps to return to service averting the risk for the custome

Creating and curating an archive: Bury St Edmunds and its Anglo-Saxon past

This contribution explores the mechanisms by which the Benedictine foundation of Bury St Edmunds sought to legitimise and preserve their spurious pre-Conquest privileges and holdings throughout the Middle Ages. The archive is extraordinary in terms of the large number of surviving registers and cartularies which contain copies of Anglo-Saxon charters, many of which are wholly or partly in Old English. The essay charts the changing use to which these ancient documents were put in response to threats to the foundation's continued enjoyment of its liberties. The focus throughout the essay is to demonstrate how pragmatic considerations at every stage affects the development of the archive and the ways in which these linguistically challenging texts were presented, re-presented, and represented during the Abbey’s history

Care home environments, rehabilitation and older persons: a survey of current service provision in England

The emergence of the intermediate care agenda has added momentum to the debate on the use of alternative care settings for the delivery of rehabilitative interventions for older persons. This paper reports on the findings of the first stage of a research programme to investigate the extent of the use of care home environments for the rehabilitation of older people in England. Stage two of the project will explore in more depth the characteristics of the rehabilitation provision identified in stage one

Care home rehabilitation schemes: further findings from a national survey

The continued expansion of the intermediate care initiative has resulted in the use of alternative care settings, such as nursing and care homes, for the delivery of rehabilitative interventions for older people. In this paper, we report on the findings from the second stage of a national survey of rehabilitation schemes that use care home settings. The survey reveals a wide range of approaches and standards, leading us to ask whether there is a gap between policy goals, good practice and actual service provision. The care home rehabilitation schemes were selected on the basis that they offered, as a minimum, rehabilitation to improve an older person's physical status

Care home versus hospital and own home environments for rehabilitation of older people

Background Rehabilitation for older people has acquired an increasingly important profile for both policy-makers and service providers within health and social care agencies. This growing demand for rehabilitation services has generated an increased interest in the use of alternative care environments, for example care home environments, for older persons' rehabilitation. At a time when there is pressure for policy decision-makers and service providers to explore the use of such care settings for the provision of rehabilitation for older people, there appears limited evidence on which to base decisions. Objectives The objective of this review is to compare the effects of care home environments (e.g. nursing home, residential care home and nursing facilities) versus hospital environments and own home environments in the rehabilitation of older people. Search strategy The following databases were searched. The Cochrane Effective Practice and Organisation of Care Specialised Register, the Cochrane Rehabilitation Specialist Register; Cochrane Controlled Trials Register (CCTR); MEDLINE (1966-2000); EMBASE (1980-2000), Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982-2000): Science Citation Index (1982-2000); Social Science Citation Index (1982-2000); Best Evidence (1991-2000); HMIC (1979-2000); PsycINFO(1967-2000); ASSIA (1987-2000); Ageline (1978-2000); AgeInfo (1971-2000); Sociological Abstracts (1963-2000); System for Information on Grey Literature (SIGLE) (1980-2000); UK National Research Registers Project Database( Issue 1 2001); Architecture Publication Index (1977-2000). The following Journals were hand searched: Disability and Rehabilitation (1992-2000); Disability and Society (1986-2000); Archives of Physical Medicine and Rehabilitation (1985-2000); Journal of the American Geriatric Society (1980-2000); International Journal of Rehabilitation Research (1980-2000); American Journal of Physical Medicine and Rehabilitation (1980-2000) and: Clinical Rehabilitation (1992-2000). The reviewers also consulted subject area experts and obtained full text review articles and forward tracked any references from these sources. Selection criteria Randomised controlled trials (RCTs), controlled clinical trials (CCTs), controlled before and after studies (CBAs) and interrupted time series (ITS) that compared rehabilitation outcomes for persons 60 years or older who received rehabilitation whilst residing in a care home with those for persons 60 years or older who received rehabilitation in hospital or own home environments. Primary outcomes included functional outcomes using activities of daily living measurement (both personal and instrumental). Secondary outcomes included subjective health status; quality of life measures; return to place of usual residency; all cause mortality; adverse effects; readmission to an acute care facility; patient and carer satisfaction; number of days in facility and number of days receiving rehabilitation. Data collection and analysis One reviewer (DW) completed the initial search and identified potential papers for inclusion. Abstracts for these papers were independently scrutinised by two reviewers (DW/MS) to assess their eligibility. Full text versions of potentially eligible papers were independently assessed by two reviewers (DW/MS). Papers that fulfilled the comparison inclusion criteria were then independently scrutinised by all reviewers to assess whether they met EPOC methodological criteria for inclusion. Main results The total yield from the initial search strategy was 19,457. A total of 1,247 abstracts were independently scrutinised by two reviewers (DW/MS) to assess their eligibility. Full text papers for 99 studies were obtained to assess if they fulfilled the review's comparison inclusion criteria. This process resulted in 12 papers being assessed further for methodological validity. However, none of these studies met the inclusion criteria. Authors' conclusions There is insufficient evidence to compare the effects of care home environments, hospital environments and own home environments on older persons rehabilitation outcomes. Although the authors acknowledge that absence of effect is not no effect. There are three main reasons; the first is that the description and specification of the environment is often not clear; secondly, the components of the rehabilitation system within the given environments are not adequately specified and; thirdly, when the components are clearly specified they demonstrate that the control and intervention sites are not comparable with respect to the methodological criteria specified by Cochrane EPOC group (Cochrane 1998). The combined effect of these factors resulted in the comparability between intervention and control groups being very weak. For example, there were differences in the services provided in the intervention and control arms, due possibly to differences in dominant remuneration systems, nature of the rehabilitation transformation, patient characteristics, skill mix and academic status of the care environment