water-ring pump
38. Which of the materials listed is used as the dynamic seal material on mechanical seals installed on most centrifugal pumps used in water service?
A. Copper B. Copper and carbon C. Carbon D. Bronze 39. Which of the following actions should be taken if during a routine maintenance inspection of a centrifugal pump, localized scoring on a pump shaft sleeve is detected?
A. Correct the cause of the scoring and repair the sleeve or replace with a new one. B. Reassemble the unit and provide more water leak off for proper lubrication. C. Check for parallel alignment of the sleeve radial faces to the sleeve bores. D. Reassemble the unit and adjust the governor to obtain a slower speed.
40. When starting a reciprocating pump, the discharge valve should be ______. A. closed B. opened fully C. cracked open D. partly open
41. While flowing through the volute in a centrifugal pump, part of the ______energy of the liquid is converted to ______energy.
A. kinetic/pressure B. kinetic/essential C. pressure/kinetic D. pressure/height
42. Gear pumps are ______because they discharge a near constant amount of liquid regardless of pressure.
A. negative displacement type B. turbine type
C. positive displacement type D. mixed-flow type
43. Operating a rotary pump at speeds in excess of design requirements could cause______.
A. decreased clearances between rotating parts
B. decreased slippage to the suction side of the pump C. air binding in the discharge ports D. erosion and excessive wear
44. The fire pumps must be capable of delivering a total quantity of water at a defined head , not less than______ of the total bilge pumping capacity.
A. one-third B. two-thirds C. one-fourth D. two-fourths 45. Which of the following will be the advantage of a centrifugal pump as compared with a reciprocating pump? I. Its discharge is continuous; II. It has no internal valves; III. Upon accidental closing of discharge valve, excessive pressure will not build up
A. I, II B. II, III C. I, II, III D. II only 46. Why are removable sleeves installed on centrifugal pump shafts? A. They make it easier to replace the pump shaft packing. B. They can be economically replaced as they wear out.
C. They can be removed when it is necessary to lighten the weight of the pump. D. They increase the strength of the shaft.
47. Which of the listed statements is correct concerning the starting of centrifugal pumps?
A. They should always be started with the discharge valve closed. B. They should always be started with the discharge valve opened.
C. A priming pump is always required to flood the impeller suction. D. They should always be started with the sealing line valves closed.
48. The simplest method to use for determining if a centrifugal pump is operating as designed, is to ______.
A. closely observe the pump discharge temperature
B. close off the discharge valve, and watch for a rise in pressure
C. momentarily close off the suction valve, and watch for a rise in pressure D. use a clamp on ammeter and compare the readings to past records 49. A ______in the air delivery line near to each compressor is essential.
A. butterfly valve B. globe valve C. gate valve D. non-return valve
50. The value of GM still remains one meter, meanwhile we can pump the ballast water to ______the ship on the even keel.
A. make B. put C. keep D. get 51. Grind the ______.
A. keyway B. shaft C. packing D. valve
52. The valve best suited for throttling gas or liquid flow in a pipeline is the ______. A. gate valve B. globe valve C. check valve D. plug cock
53. To maintain the down stream pressure within defined limits over a range of flow and despite any changes in supply pressure, ______is fitted.
A. a check valve B. a gate valve C. a pressure reducing valve D. a quick closing valve
54. Which of the following statements describes one of the functions of the ballast system?
A. To permit flooding of any fuel oil storage tank on any class of ship. B. To use it as a secondary service system.
C. To store reserve feed or potable water for extended cruises.
D. To stabilize the ship by flooding certain designed tanks with seawater.
55. Where tanks are arranged for either oil or ballast ______must be fitted in the pipeline.
A. a change-over chest B. a head tank C. a emergency bilge pump D. an air cooler
Lesson 16 Marine Boilers
单项选择题：
1. _______ are mounted in pairs to protect the boiler against overpressure. A. Safety valves B. Water tubes C. Steam stop valves D. Blow down valves
2. A donkey boiler is _________.
A. one to supply steam to the main propulsion turbine B. an auxiliary boiler C. A and B
D. neither A nor B
3. Impurities from the boiler water surface can be removed through the ______. A. safety valve B. blow down valve C. scum valve D. feed check valve 4. In motor ship, _______ is often used to recover some of the heat carried in the exhaust gases from the main engine. A. an diesel oil heater B. a waste heat boiler C. a fresh water generator D. all the above
5. ________ will be used to blow away the combustion products from the tube surfaces.
A. The blow down valve B. The scum valve C./ The air release cock D. The soot-blower 6. W.H.R. stands for ________. A. Water Head Register B. Water Heater Re-circulating C. Waste Heat Recovery D. Waste Handle Reference
7. ________ is the production of pure water from sea water by evaporation and re-condensing. A. Evaporation B. Circulation C. Condensation D. Distillation 8. When a vacuum boiling evaporator works, the hot jacket water will pass over the tube stack and _______ the sea water passing through the tubes. A. dispose B. dissolve C. heat D. dissipates
9. With a vacuum boiling evaporator, the remainder of sea water fed to the evaporator is pumped out by _______. A. a brine pump B. an air ejector C. a feed pump D. distillate pump
10. In a vacuum boiling evaporator, the fresh water generated is pumped out by _______.
A. a brine pump B. an air ejector C. a feed pump D. a condensate pump
11. The process during which liquid containing a reasonable amount of sensible heat at a particular pressure immediately changes into steam after admitted to a chamber at a lower pressure is called ________. A. boiling off B. flash evaporation C. condensation D. none of the above
12. Large pipes or down-comers are fitted between the steam drum and _______ to ensure good natural circulation of water. A. fire-tubes B. furnaces C. water drums D. water wall tubes
13. Large pipes or _______ are fitted between the steam and water drums to ensure good natural circulation of water. A. fire-tubes B. furnaces C. down-comers D. soot-blowers
14. Additional heat extraction from the exhaust gases can be effected by adding an _______ section to the unit in plants. A. air cooler B. economizer C. injector D. air blower
15. The exhaust boilers are used to recover some of _______ carried in the exhaust gas from the main engine. A. water B. oil C. heat D. steam
16. The safety valves are mounted in pairs to ________ the boiler against overpressure. A. use B. release C. protect D. effect
17. The safety valve should be ______ in the presence of C/E and Surveyor. A. tightened up B. sealed up C. opened up D. unscrewed
18. Between the steam drum and the smaller water drum below, large numbers of smaller diameter _______ tubes are fitted. A. fire B. water wall C. generating D. down comer 19. A ________ boiler is an auxiliary boiler sometimes included in a steamship?s installation for supplying steam to auxiliaries in port. A. monkey B. donkey C. waste heat D. main
20. Water evaporates or steam condenses at the saturation temperature, which depends upon the pressure, the higher the pressure ________ the saturation temperature. A. the more B. the higher C. the lower D. the highest
21. Because of the reduced _________ in the vacuum boiling evaporator, some of the sea water boils as it flows through the tubes. A. temperature B. water level C. pressure D. rate of flow
22. More than one stage of evaporation can take place by admitting the sea water into chambers with progressively _______ pressure in the flash evaporator. A. lower B. higher C. the lower D. the higher
23. In _______, hot diesel engine jacket water passes over the stack and heats the sea water passing through the tubes. A. a flash generator B. a flash evaporator C. a vacuum boiling evaporator D. a boiler
24. ________ will be used to blow away soot and the combustion products from the tube surfaces.
A. The blow down valve B. The scum valve C. The air release cock D. The soot-blower
25. Which of the following descriptions best identifies the operating principle of a flash-type evaporator?
A. Sea water is heated to boiling temperature while under a vacuum B. Sea water is passed over heated plates in a thin film C. Heated sea water is injected into a vacuum chamber D. Sea water is forced through a heated eductor
26. The exhaust boilers are used to recover some of ______carried in the exhaust gas from the main engine.
A. water B. oil C. heat D. steam
27. Fins are installed on the generating tube surfaces in waste heat boilers to ______. A. prevent soot fires in the exhaust system B. prevent exhaust gas erosion of the tubes
C. increase the velocity of exhaust gas flow D. increase the rate of heat transfer
28. Less scale formation occurs in a flash evaporator than in a submerged tube evaporator because ______.
A. the distillate produced has greater purity B. no boiling occurs on heat transfer surfaces
C. evaporation occurs at a higher rate D. the incoming feed is at a higher temperature
29. Which of the following descriptions best identifies the operating principal of a flash-type evaporator?
A. Sea water is heated to boiling temperature while under a vacuum. B. Sea water is passed over heated plates in a thin film. C. Heated sea water is injected into a vacuum chamber. D. Sea water is forced through a heated eductor.
30. The purpose of the safety relief valves installed on an auxiliary boiler is to ______. A. relieve excess fuel oil pressure during the “ off ” fire cycle B. admit water to the dry pipe
C. throttle the forced draft fan output for proper combustion D. reduce excess steam pressure in the boiler
31. Fusible plugs are installed in fire-tube boilers to ______.
A. provide a means of draining the boiler B. warn the engineer of low water level
C. cool the crown sheet at high firing rates D. open the burners' electrical firing circuits
32. A donkey boiler is ______.
A. one to supply steam to the main propulsion turbine B. an auxiliary boiler
C.AandB D. neither A nor B
33. Which of the following statements concerning fire-tube boilers is correct?
A. Combustion gases flow through the tubes. B. Flames impinge on the tubes. C. Combustion occurs in the tubes. D. Water flows through the tubes.
34. In which of the areas listed would you expect to find the highest salt concentration in a flash evaporator?
A. Distiller air ejector cooling medium B. Saltwater heater discharge C. First-stage internal feed box D. Second-stage internal feed box
35. With a vacuum boiling evaporator, the remainder of sea water fed to the evaporator is pumped out by ______.
A. a brine pump B. an air ejector C. a feed pump D. distillate pump
36. When a flash-type evaporator is to be secured for an extended period of time, the entire unit should be drained, cleaned, and ______.
A. completely filled with saltwater B. filled with de-scaling compound C. tightly closed to exclude air D. vented to the atmosphere
37. The flame safeguard control system of a large automatic auxiliary boiler will provide fuel shut off in the case of high ____________.