Методичка по английскому языку для ИТС (пр. С.С.Иванов)
.pdf550 kVA, and should this go above 600 kVA on those in circuit , then another generator cuts in automatically and will cut-out when the output drops to 500 kVA. For operation of the bow thruster it is necessary to have at least four generators on load . When manoeuvring it is possible to switch in additional generator on 'secured running', thereby ensuring that the bow thruster is immediately available for example without the possibility of loosing this power at an awkward moment due to a temporary drop in overall power requirements. Steam is obtained from two Wartsila Steambloc 600 M donkey boilers, each of which has a capacity of 6.3 ton/h at a pressure of 8 kp/cm2 . Two waste heat boilers also of Wartsila supply , have a capacity of 3 ton/h each.
The ship's fresh water supply is obtained from an Atlas AFGU No.9 evaporator utilising the waste heat from the main engine cooling water and two Alfa-Laval/Griscom Russell Steam-driven evaporators. These three units can supply a total of 300 tons of water per 24 hours.
Notes
exhaust gas boiler - утилизационный паровой котел
subsidiary - вспомогательный
power train – силовая цепь
gear - box – коробка передач
clutchсцепление , муфта
shafting - валопровод
alternator – генератор переменного тока
distribution board – распределительный щит
should - если
on load – под нагрузкой
evaporator – опреснитель
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Grammar
Write out of the passage terms consisting of three or more words and translate them.
Sea trials
Preliminary trials with 'Song of Norway' commenced about three months before the delivery date. Local vibrations in important deсk areas were measured during these trials and by the addition of small amounts of stiffening in these areas and also in the bridge wings very satisfactory noise and vibration levels throughout the ship have been obtained.
During early speed trials in calm water at an engine output of 18000 bhp , when on an even keel at a draught of 6.3 m. a speed of 21.7 knots was attained. The ship's hull had not been cleaned prior to these trials, however, and the performance suffered because of eight months accumulated marine growth on the hull.
At the official trials under the same ship conditions the speed attained was 21.35 knots, but on this occasion the trials were run in Beaufort 5-7 conditions. Under ideal conditions it is estimated that the contractual speed of 21 knots would be exceeded by about one knot.
Notes
Beaufort scale – an international scale of wind velocities ranging from 0 (calm) to 12 (hurricane force).
In the US an extension of the scale from 13 to 17 for winds over 64 knots is used.
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Captain R.W. Goode and Mr. J.M. Logan
PROPULSION GAS TURBINE EXPERIENCE ON THE COAST GUARD HAMILTON CLASS HIGH ENDURANCE CUTTERS
The Authors
CAPT. R.W. GOODE, a native of Maine, graduated from U.S.C.G academy in 1944. He served in the Asian and European Theaters on board a troop transport as assistant engineer officer. Other tours at sea have included engineering and deck duty on various Coast Guard Cutters employed in search - and - rescue and ocean station programs. He attended MIT Graduate School from 1949 to 1952 and was awarded the degree of Naval Engineer. During the years 1960 - 1964, he was head of the electrical and nuclear engineering courses at the Coast Guard Academy.
Mr. Logan received a B.S. degree from the U.S. Naval Academy in 1943. He held engineering positions both in and out of the marine field before joining the Coast Guard Naval Engineering Design Branch in 1957. He was project engineer on several classes of new ship machinery designs including the subject 378-ft. HAMILTON Class High Endurance Cutters. Presently, he is Chief, Machinery Technical Section, Design Branch of the Naval Engineering Division.
EDITORS NOTE: Presented at the Gas Turbine Conference and Products Show, Cleveland, Ohio, March 9-13, 1969, of the American Society of Mechanical Engineers.
I n t r o d u c t i o n
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This paper will review the engineering problems encountered with the P & WA FR4A gas turbine on the Coast Guard 378-ft. H a m i l t o n Class Cutters, Fig. 1. It is only fair to say that the majority of the problems were in the associated systems rather than within the gas turbine itself.
No effort will be made in this paper to describe in detail the overall machinery plant design as this has been documented in a previous paper. However, a brief description will be made of components and systems involved in the shaking-down process experienced on the ships, along with the solutions of the numerous problems encountered.
The Coast Guard has taken delivery of six Hamilton class cutters at this writing, with three more due under an existing contract.
Gas Turbine Starting System
The first marine application of a hydraulically started large aircraft type gas turbine was on the USCGC Hamilton. The hydraulic starting system consists of a variable displacement piston pump powering a variable displacement piston starting motor. Both pumps, one per turbine, are timing belt-driven by the front end of each ship service diesel generator set. The capability of unlimited motoring is well suited for the demands of prolonged water washing.
The positive starting characteristics of hydraulic starting should have guaranteed reliable starts; this assumption proved to be wrong. This is not a reflection on hydraulic starting, since starting problems were due to use of No.2 diesel fuel instead of the usual JP-5. P & WA proposed that an air boost system be incorporated into the fuel system to provide reliable starts. This retrofit involved setting aside one of the three diesel starting air tanks (250 psi) for gas turbine use. The air boost feature requires air at 150-250 psi during the starting cycle. Air is introduced into the secondary fuel line to the nozzles and exits through the nozzle secondary openings to provide improved atomization of the fuel. This modification resulted in consistently reliable starts. Initially, it was proposed that the fuel be heated to overcome the
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starting problem, but the success of the air boost system on the CG cutters proved this to be unnecessary.
Notes
variable displacement piston pump – поршневой насос переменной производительности
variable displacement piston motor –поршневой двигатель переменной производительности
timing belt - driven – с синхронным ременным приводом diesel generator set – дизельная генераторная установка unlimited motoring – неограниченный моторесурс
water washing - промывка
should – в сочетании с перфектным инфинитивом означает что действие должно было бы иметь место , но не произошло
assumption - предположение
to be due – зд. быть обусловленным
air boost system – система воздушного наддува, бустерная система retrofit – модификация; переостнастка
involve – влечь за собой feature - особенность nozzle - сопло
psi – фунт на кв. дюйм
Fuel System
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The fuel is transferred from the storage tanks to a 30,000 - gal service tank by a 140 gpm transfer pump discharging through a Bowser - Briggs coalescing type filter - separator. A centrifuge was not feasible because we required propulsion equipment to be designed to high impact shock Standards ( MIL- S - 901 ). This ruled out all but one large industrial centrifuge ( 10,000 gph ). A fuel boost pump ( 70 gpm ) takes suction from the service tank and discharges through a second slightly smaller, filter - separator to the gas turbines. The fuel filtration system became troublesome almost immediately. The ships were plagued by rapid plugging of the transfer coalescer filter elements. The element life was limited to approximately 10 - 20 thousand gal. This required changing 20 coalescer elements and 9 separator elements at a cost of over $400 and 3 to 4 hr. for each changeout. The short filter life was intolerable, especially in view of the 300-gph fuel rate when cruising in the turbine mode. Each coalescer filter element had a nominal dirt holding capacity of 2 lb. when the differential pressure reached 15 psi. This meant that the transfer coalescer elements were taking out approximately 40 lb. of dirt per 20,000 gal of fuel. Extremely dirty fuel storage tanks were first suspected, which seemed plausible since the ship had only recently left the building yard. Investigation, however, revealed the tanks to be reasonably clean. The elements were sent to a laboratory for testing and found to have trapped only a few ounces of dirt, but contained slime-like matter which caused blockage and the resulting P of 15 psi.
The slime was the product of microbiological growth which, in turn, was direct result of ballasting the fuel storage tanks when empty of fuel. Whenever sea water ballast was removed prior to taking on fuel, a small amount of water would remain providing the ideal environment for the growth of microorganisms at the fuel/water interface. Microorganisms in diesel fuel manifests itself as sludge and slime. These microbial slimes cause excess water and particulate matter to become suspended in the fuel. It was this growth that primarily caused the exceedingly short filter life. Microbiological growth has been a problem in marine, railroad, and aircraft fuel systems for years, but has gone largely unrecognized. Investigation into the " state of the art " regarding microbicides revealed that a fuel soluble boron compound, developed by Standart Oil Co. (Ohio) and marketed by U.S. Borax under the name Biobor JF, was effective in inhibiting the formation of the bothersome slime. Biobor JF was added to the storage tanks
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in amounts equalling 270 ppm; experience to date has shown Biobor JF to be compatible with both the gas turbines and the diesel engines.
The filter element life, though now improved, continued to have relapses as the fuel quality taken on at some ports proved to be very erratic. It was felt that efforts should be made to use the coalescer filters for water removal instead of a combination water and particulate filters. A pre filter was purchased and installed ahead of the transfer coalescer filter. Initially, the filter opening size was equal to the coalescer elements (MIL-F-8901). However, it was found that the fine dirt continued to be trapped in the coalescer elements . The prefilter elements were replaced with finer elements, and were able to trap most of the fine particulate, leaving the coalescer elements with the principal function of removing water and extending the elements life. The prefilter consisting of four elements went as long as 130000 gal. between changeouts. This reduced the elements cost to 0.02 cent per gal. of fuel, which is felt to be an acceptable price to pay to maintain a high degree of filtration.
Notes
coalescer filter коалесцирующий фильтр
blockage - закупорка
storage tank – цистерна для хранения топлива
service tank – эксплуатационная цистерна
gpm – галлон в мин
transfer pump – насос подачи топлива
coalesing type filter - separator – фильтрсепаратор коалесцирующего типа
feasible - приемлемый
high impact shock Standards – стандарты высокой ударной вязкости
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troublesome - аварийный
plugging - закупорка
element life – срок службы элемента
cost - стоимость
intolerable - неприемлемый
turbine mode – режим турбины
plausible - вероятный
ounce - унция
slimelike – похожий на ил
ballasting – балластировка, заполнение балластом
interface – поверхность раздела двух сред
manifest itself – проявлять себя , проявляться
" state of the art " – состояние вопроса
fuel soluble boron compound – растворимое в топливе соединение бора
compatible - совместимый
Air Intake System
The gas turbine inlet air vent is located on the 02 deck, where the intake air passes down through a 9 ft. by 6 ft. duct to a 10 ft. by 13 ft. plenum chamber located forward of the engine room. The turbine inlet bellmouth extends into this plenum.
The air intake system was designed with a maximum air inlet restriction of 4 in. of water gage as the governing parameter. The air intake system was model - simulated and tested by the manufacturer. The specified full power rating ( 18,000 shp ) produced an air restriction of 2 1/2 in. H2 O. An excess capacity was designed into the system to allow for a demister, if required.
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The purpose of a demister, is to minimize the ingestion of salt spray with the inlet air and the resulting sulfidation. An inertial type air inlet demister manufactured by the Farr Co. has been considered and a prototype has been installed on a 210 - ft. CODAG cutter for evaluation.
Corrosion of the compressor inlet guide vanes and inlet casing of both gas turbines became a problem on the first Cutter. The inlet vanes and casing are constructed of nickel cadmium plated steel. Long periods of exposure to the weather in the shipyard plus the original water wash procedure combined to remove part of the protective cadmium plating. The gas turbine installation angle is approximately 5 deg, down by the output coupling. This angle cancels the flare of the inlet casing, allowing the water remaining after washing to accumulate in the forward casing. To alleviate this condition, a detergent compound ( HARCO 141 ) was added to the distilled water wash. In addition, the turbine was motored with the anti - icing system on for 15 min after completing the wash. This procedure is now standard on all cutters with excellent results.
The following factors influenced the decision not to install an air inlet demister at this time:
( a ) The protected location of the air inlets on the 02 deck.
( b ) The improved water wash procedure.
( c ) The use of air inlet covers during periods of turbine shutdown to prevent air circulation.
A turbine inlet screen is provided in the plenum chamber. This consists of a cylindrical 1/2 - in. mesh stainless steel screen installed fore - and - aft enclosing the gas turbine bellmouth and attached at each end to the forward and after walls of the plenum. There was fear that the mere presence of the screen together with the structural frame would generate flow distortions and increase the inlet restriction. Pressure measurements taken during trials have shown that the screen has no detrimental flow or pressure effects. In addition, the manufacturer expressed concern that icing might become a problem and cause a section of the screen to be ingested into the turbine. However, the screen is sufficiently oversized to allow 3/4 of the area to be blocked without air starvation. In the event icing is expected, the lower quadrants of the screen
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can be removed as a safeguard. However, to date icing has not been experienced.
Notes
air vent – вентиляционное отверстие duct – канал, воздухопровод
plenum chamber – воздушная (нагнетательная) камера inlet bellmouth – входной раструб
restriction - ограничение
water gage – водяной манометр
model - simulated and tested – смоделированный и испытанный на модели
demister – устройство для удаления паров из воздуха ingestion – зд. смешивание
sulfidation - сульфидация
guide vane – направляющая лопатка casing – кожух, корпус
cadmium plated – с кадмиевым покрытием coupling - муфта
cancel – сводить на нет, устранять flare - выпуклость
detergent compound – состав, содержащий моющие присадки
Exhaust System
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