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2nd Engineer > 2nd Engineer > Flashcards

2nd Engineer Flashcards

1
Q

What happens if you lose the turning gear on large turbine while shutting down ?

A

If you cannot get it back on line you may have to admit steam to roll it while you repair it. If no steam availible you may need to turn it by hand

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2
Q

How is the efficiency of steam turbine increased ?

A

1 Super heat steam 2 Use a condencer 3 Reheat the steam

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3
Q

What are two principles of turbine operation ?

A

Impulse and reaction. Impulse is the energy imparted to a set of turbine blades by impack. Reaction is force exerted on the blades as the expanding steam leaves the blades

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4
Q

What besides thrust bearings is used in a reaction turbine to absorb thrust ?

A

A dummy piston

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5
Q

What are two things your first stage pressure indicates?

A

1 Amount of load change 2 Boiler pressure change. 3 Vaccune changes. 4 Deposits on the blading

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6
Q

What causes most damage, loss of thrust bearing or a journal bearing ?

A

The loss of thrust bearing would cause severe damage.Loss od journal would cause localized damage

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7
Q

Why does the ASME recommend that welded seams be e-xrayed?

A

To determine that full penetraction of weld and no hidden flows.

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8
Q

What are four modes of failure in a single lap joint ?

A

1 The shearing strength of rivets
2 The crushing strength of the plate in front
3 Strength of the solid plate
4 The stregth of the plate between rivet holes

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9
Q

What is the heat balance in a steam generating unit ?

A

Heat balance is the distribution of the heat absorbed by the boiler and the losses which occur in the operation of the plant.

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10
Q

What are three conditions necessary for caustic embrittlement to happen ?

A

High alkalinity, Microsopic cracks and leaks for the alkalinity to accumulate and highly stressed areas for reaction to take place.

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11
Q

What fourconditions are prevented by proper water treatment ?

A

Priming and carry over, caustic embrittlement, scale formation and corrosion.

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12
Q

List six gases or gaseous mixtures found in a typical flue gas analysis ?

A

1CO2 O2 N2 SO3 CO H2O SO2 NOX

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13
Q

Which takes moore total air for combustion, 1 pound of oil or 1 pound of pulverized coal ?

A

One pound of oil requires moore air because it has moore heat units.

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14
Q

Which fuel gives higher co2 readings, oil or gas ?

A

Oil gives higher co2 reading than gas, oil about 15.6 5 and gas around 12 %

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15
Q

If a handhole opening is corroded may it be built up on outside by welding ?

A

Yes providing that at least 50% of orignal thickness is present and the corrosion does’t extend moore than 3 inches

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16
Q

How may lap cracks be repaired ?

A

No repairs on lap cracks are permitted unless a new course of boiler plate is installed . If not the boiler must be condemned.

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17
Q

With a 4” saftey valve what is minium size conected to nozzle ?

A

4”

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18
Q

What is Electrolysis?

A

Electrolysis is corrosion caused by the externally applied electrical current

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19
Q

DefineSpecific Heat,Relative Humidity and Adiabatic

A

SH Heat required to raise a substance 1F and expressed in relation to water (1.0)
RH Amount of humidity in the air at specific temp and pressure compared to amount if saturated. Adiabatic the process that producers the loss of no heat during work taking place.

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20
Q

How does a retractable sootblower work ?

A

Located outside of the boiler , when in operation it moves in and out of the tube banks in a swival pipe which spins the moving element . Steam is that directed in appropriate direction.

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21
Q

List 6 causes of turbine vibration ?

A

1 low oil temp 2 critical speed 3 wiped bearing 4 moisture carry over 5 unbalanced rotor 6 high pressure 7 misaligned bearings

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22
Q

How can you tell if a feedwater heater has a leak on it tube side ?

A

It will result in increase in make up water and temperature of feed water will decrease.

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23
Q

Describe the operation of a air ejector ?

A

Steam enters the nozzle and is expended. The increase in velocity and decrease in pressure. Steam passes into the suction chamber and draws air and other non-condensibles from the condencer. These gases are condensed in the inter-condenser. For higher vaccume a second stage is added taking suction from the intercondenser and discharging to an after condenser with the gases (air and noncondensibles) discharging to atmosphere and steam condensate back to condensate system.

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24
Q

What is Carnot Efficiency, Rankine Cycle Efficiency?

A 
Carnot formular for ideal efficiency.
T1-T2/T1
Rankine takes into account losses and compares to ideal.
h1-h2/h1-hf2
hf2 =enth >32F
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25
Q

Why would use a non-condensing turbine ?

A

If your plant required large amount of low pressure steam for process.

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26
Q

Does a double plate increase ligament efficiency?

A

No it does not as it is not included in the formular. It does however increase the thickness of the boiler plate in ligament section increasing the MAWP.

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27
Q

When should air tanks be inspected ?

A

over 50 psi every 2 years

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28
Q

What is more important ,Axial or Radial clearance ?

A

Radial clearance is more important as ther is a pressure differential across the moving blades and ther is leakage past the blades.

29
Q

What ia a Watt ?

A

A bascic unit of electrical power. It is calculated by multiplying the voltage by the current.
W=ExI

30
Q

What is rotor long ?

A

Is a condition which develops when the turbine is warmed too quickly. The rotor expands more quickly than the casting due to smaller mass.

31
Q

Why is turbine speed governed by cutting out nozzles ?

A

To cut throttling losses. The nozzles are aranged on a lifting bar which allows them to be opened in groups. Each group is then controlled by seperate admission valve.

32
Q

What is blade gaging ?

A

Blade gaging is the reduction of exit angle on the blades in the last two stages of turbine. lARGE VOLUMES OF LOW PRESSURE steam is then allowed a rapid escape.

33
Q

Conduct an overspeed trip.

A

With one man a throttle valve keeping it open, another at the tachometer and another vat the manual trip, slowly run up the turbine. At 10%over its rated speed it should trip.The actual speed it trips at should be recorded.

34
Q

What is the formula for turbine horsepower ?

A 
Wsx(h1-h2)/2545
Ws=weight of steam
h1=Enthalpy of admission steam
h2=Enthalpy of exhaust steam
2545=amount of BTU'S in one horsepower
35
Q

What isthe main purpose of a nozzle in a steam turbine ?

A

Expand the steam decreasing its pressure and increasing its velocity. This converts potential energy into kinetic energy.

36
Q

How can you tell if rolled tubes are tight ?

A

When you can see cracks in the mill scale. The best way is to give them a hydrostatic test.

37
Q

What is psia. If barometer reads 29.4 and the gage reads 26’’ ?

A
  1. 4-26=3.4

3. 4x.491=1.67 psia

38
Q

What is the formular for theoretical air needed to burn one pound of fuel ?

A

11.53C+34.56(H0/8)+4.32S

39
Q

Why is moore attention given toSO2 emissions ?

A

Due to clean air act of 1973. SO2 reacts with moisture in air forming sulfurous Acid Rain

40
Q

What are fuel additives used for ?

A

anti-emulsifiers anf anti-bacteral agents

41
Q

A furnace of 13000 cu.ft burns 7 tons of 13500 btu/ton coal per hour. What is the heat release?

A

H.R. is the amount of heat energy in btu’s. released per unit volume of furnace.
H.R.= 13500x7/1300=7.27 btu’s

42
Q

Name seven losses occur in a coal fired boiler ?

A

1 losses due to amient moisture

2

43
Q

What is code requirement when two safety of different sizes?

A

The smaller one has to be at least 50% of the larger one.

44
Q

When is the best economy obtained for impulse and reaction turbine ?

A

When a condenser is used.

45
Q

Line up and start a condensing tirbine.

A

1 Establish cooling water flow
2 Open all drains
3 Start your lube oil system and test standby pump.
4 Put hogger into service and close vaccume breaker
5 Keep an eye on lube oil system check for leaks and levels
6 When you get to 10’’ of vaccume slowly admit steam and roll turbine. Check for rubbing or squealing. Let casting and rotor warm up together.
Start air ejection. slowly bring up turbine.
Do an overspeed test and bring back up to speed.
7 Monitor your instrumentation and after the govener taken control, open throttle valve wide.
8 Close all drains

46
Q

Why is a reheater used?

A

A reheater takes steam from the intermediatev areas of the turbine and passes it through the gas passes of the boiler. This adds heat energy and increases it’s efficiency. Also condensations losses are reduced.

47
Q

What isthe purpose of the gland condenser ?

A

Is to recover the steam used to seal the turbine and raise the ovrrall efficiency.

48
Q

What are six losses in a turbine ?

A 
1 Radiation
2 Windage
3 Eddy losses
4 Friction at the surface on which steam flows
5 Bearing friction
6 Leakage loss
49
Q

What are three ways to connect a to a condenser ?

A

1 Bolt it to exhaust and support on springs
2 Set it on saddles and connect with expansion joint.
3 Support an extension of the turbine seperatley and connect with an expansion joint.

50
Q

What are four types of flame detectors devices ?

A 
1 Catmium sulfide photocell.
2 Lead sulfide photocell
3 Rectifying phototube
4 Rectifing flame rod
5 Ultra-violet flame detector
6 Stack switch
51
Q

What is procedure for adjusting radial clearances ?

A

You must use liners that may be implanted or removed from under thr journal bearing

52
Q

Name three reason for load reduction in a turbine over a few days.

A

If your plant is air cooled condenser its ability to condense steam is dependent on ambient air. A low pressure front in your area will also decrease the vaccume in both surface and air cooled condenser. A surface condenser may be foulling .Any water treatment problems resulting in foarming or priming may reduce load

53
Q

Solve for p

A

t=d/cp/s p=(td)xs/c

54
Q

What are the two most important clearances in a turbine ?

A

axial and radial

55
Q

What are 6 methods for controlling superheat ?

A 
1 Use of atemperator
2 Use of tilting burners
3 Use of bypass dampers
4 Location of superheater
5 Separately fired superheater
6 Radiant and convection superheaters
56
Q

How do zeolite softeners work ?

A

Water pases through the zelite bed and exchanges it ‘‘hard’’ Magnesium and Calcium ions for ‘‘soft’’ Sodium ions which results in salts which may be blown downinstead of scale.

57
Q

Name 6 turbine trips ?

A 
1 Overspeed
2 Low oil pressure
3 High vibration
4 High bearing temperature
5 High exhaust temperature
6 High and low steam temperature
7 Reverse current
58
Q

Acording to the ASME which heads need no stays ?

A 
1 Segment of a spere 
2 Semi-ellipsoidal
3 Hemispheric
4 Flatheads
5 Dished heads
59
Q

In an air ejector how is the enthalpy of steam recovered?

A

The enthalpy of the steam is recovered in the condensate used in the inter and after condenser cooling medium. The heat exchanged heats the condensate and is reintroduced to the condensate system

60
Q

A boiler is running at 100 psi and thestack temperature is 300 f . There is no preheater or economizer . Is this condition normal ?

A

The corresponding saturation temp for a 100 psi is 327 f therfore it is not normal

61
Q

When you are running a boiler and its ph is high, what should you do ?

A

First thing is to check if its foarming

62
Q

Am electrical motor ,240v, 20a, power factor .9 has what horse power ?

A

240x20x.9x1.73=746 whatts/746= 1.002 HP

63
Q

What undesirabe effect would be created if a large watertube boiler supplying a turbine had its safety lify?

A

Water would rise be lifted out of the drum and this would cause carrover. A low water condition may occur or posible blade damage due to water impinging on the blades

64
Q

Why is H2 in large generators as coolant ?

A

Hydrogen has a specific heat of 3.42
,14 times greater than air. This means that per unit volume it has 14 times the coolant capacity. It also is 15 times lighter than air.

65
Q

What causes return line corrosion ?

A

low ph in the condensate it can be treated with alkallinity it can also be treated with an amine which forms a coating

66
Q

What does low air gate mean ?

A

that the combustion control system fuel will cut out before air is opposed to a high air gate where air leads the fuel

67
Q

What is turbine heat rate?

A

Wsx(hi-h2)/3413

68
Q

Describe how to do a proximate analysis.

A

First sample of coal is crushed and weighed. It is than heated to drive off moisture. The sample is then weight and the difference is the moisture content. Next the sample is heated and all volatile matter is dreven off. It is weight and the difference is volatile matter. Then the sample is burned completely and the difference between the weight of the ash is the fixed carbon . Then a portion taked prior to burning is sent to lab to determinr the sulfur

69
Q

What is spalling ?

A

Thewasting away of furnace brick work.

2nd Engineer (2 decks)

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