Clinostomum marginatum metacercaria: Incidence in Smallmouth Bass from a North Arkansas Stream and in vitro Oxygen Consumption Studies

Small mouth bass (Micropterus dolomieui) captured from Crooked Creek (Marion Co., Arkansas) in the summers of 1977 and 1987 were found to have a high incidence of infection with the metacercaria of Clinostomum marginatum (yellow grub). Of 41 fish collected in 1977, 32 (78%) were found infected with metacercariae with some fish containing large numbers of parasites. The number of larvae per fish ranged from 1 to 184, with an average of 23.2 ± 38 per smallmouth. Eighty-six percent of the bass collected in 1987 were found positive for C. marginatum. The number of metacercariae per fish ranged from 1 to 227 with an average of 32.7 ± 54 per fish. Fish from both collection groups ranged in size from 12 to 34 cm. No significant correlation could be found between the number of metacercariae per fish and the length of the host. Using metacercariae removed from host tissue, the effect on oxygen consumption by glucose, serotonin and insulin, singularly or in combination, was measured by manometric methods. Glucose alone did not stimulate oxygen utilization, serotonin alone and with glucose was stimulatory, and insulin with glucose also increased oxygen consumption

Integrally Geared Compressors

Discussion GroupHow to specify an integrally geared compressor Typical process applications Controlling an integral gear compressor - IGV, VFD Rotordynamic consideration

LNG TURBOMACHINERY

TutorialThe International Liquefied Natural Gas (LNG) trade is expanding rapidly. Projects are being proposed worldwide to meet the industry forecasted growth rate of 12% by the end of the decade. LNG train designs in the coming years appear to fall within three classes, having nominal capacities of approximately 3.5, 5.0 and 8.0 MTPA (Million Tons Per Annum). These designs may co-exist in the coming years, as individual projects choose designs, which closely match their gas supplies, sales, and other logistical and economic constraints. The most critical components of a LNG liquefaction facility are the refrigeration compressors and their drivers which represent a significant expense and strongly influence overall plant performance and production efficiency. The refrigeration compressors themselves are challenging to design due to high Mach numbers, large volume flows, low inlet temperatures and complex sidestream flows. Drivers for these plants include gas turbines that range in size from 30 MW units to large Frame 9E gas turbines. Aeroderivative engines have also been recently introduced. This paper covers the design, application and implementation considerations pertaining to LNG plant drivers and compressors. The paper does not focus on any particular LNG process but addresses turbomachinery design and application aspects that are common to all processes. Topics cover key technical design issues and complexities involved in the turbomachinery selection, aeromechanical design, testing and implementation. The paper attempts to highlight the practical design compromises that have to be made to obtain a robust solution from a mechanical and aerodynamic standpoint

Fatigue Damage Of Steam Turbine Blade Caused By Frequency Shift Due To Solid Buildup - A Case Study.

LecturePg. 107-114The case history is presented of a large steam turbine that experienced blade damage after about eight years of service. The probable cause and subsequent solution to the problem are addressed. A discussion of the metallurgical analysis of the damage, Campbell diagram, SAFE diagram and modal test results is provided. The damage is believed to have been caused by a solid build up at the blade root that shifted a natural frequency into an interference region, and changed the response characteristic of the bladed disk assembly. Proper blade design with conservative stress levels and separation of natural frequency from exciting frequency is important for reliability. If solid build up is expected, or is experienced during operation, the blade design should be reviewed for possible interference, and its effect on the resulting life of the blading evaluated

Screw Compressors

Discussion GroupAPI Standard 619 for screw compressors Wet and dry Silencers for dry screw compressors Noise reduction methods Lubricants and lubricant carryover for flooded screw compressor Over-compression and under-compression Pulsation and vibration issue

Wet and Dry Screw Compressors

Discussion Grou

Integrally Geared Compressors

Discussion GroupHow to specify an integrally geared compressor Typical process applications Controlling an integral gear compressor - IGV, VFD Rotordynamic consideration

Screw Compressors

Discussion Grou

Wet and Dry Screw Compressors

Discussion Grou

Guidelines For Specifying And Evaluating New And Rerated Multistage Centrifugal Compressors.

Tutorialpg. 215-232Refineries, petrochemical companies, and gas processors are continually trying to increase plant production while budgets are getting tighter. Rerating process centrifugal compressors has become an ever-increasing trend as a solution to this problem. Existing hardware, however, has its limitations. The limiting factors can be different for different applications of the same equipment. When rerating existing compressors cannot adequately meet increased compression production demands, new equipment must be added to an existing plant or a new plant must be built. Both of these scenarios require the purchase of new compressors. Realizing that eventually a new plant may expand or increase production to respond to increased demand, and that the differential cost for a new compressor is high, it makes sense to consider the future uprateability of new compressors when they are initially purchased and built. Discussions in this paper will give the rotating equipment engineer guidance when evaluating the design of a centrifugal compressor--either new or rerated, including a list of items that should be reviewed; and guidelines that should be followed. A case study and examples will be used to emphasize and help explain the various limiting factors for both new and rerated multistage centrifugal compressors. Cost implications and tradeoffs along with the impact on reliability will also be analyzed. With this information, the rotating equipment engineer will be able to work with process engineers to effectively optimize compressor hardware selections for the required process duty