1. © Copyright 2016Operator Generic Fundamentals Components – Heat Exchangers and Condensers

2. © Copyright 2016Operator Generic Fundamentals Terminal Learning Objectives At the completion of this training session, the trainee will demonstrate mastery of this topic by passing a written exam with a grade of ≥ 80% on the following areas: 1.Describe the purpose, construction, and principles of operation for each major type of heat exchanger. 2.Describe the purpose, construction, and principles of operation of condensers. Intro 2

3. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Construction & Operation 1.1Describe the construction, effectiveness, and operation of the following types of heat exchangers and their components (tubes, tube sheets, baffles and shells): a.Tube and shell b.Plate 1.2Describe hot and cold fluid flow paths in the following types of heat exchangers: a.Parallel flow b.Counter flow c.Cross flow 1.3Describe the difference between the following types of heat exchangers: a.Single-pass versus multipass heat exchangers b.Regenerative versus nonregenerative heat exchangers TLO 1 – Describe the purpose, construction, and principles of operation for each major type of heat exchanger. TLO 1 3

4. © Copyright 2016Operator Generic Fundamentals Enabling Learning Objectives for TLO 1 1.4Describe the operation of a typical heat exchanger to include the following: a.Startup and shutdown b.Control of temperature c.Effects and control of fouling 1.5Given the necessary data, calculate flow rates, and temperatures for various types of heat exchangers. 1.6Explain the consequences of heat exchanger tube failure. TLO 1 4

5. © Copyright 2016Operator Generic Fundamentals Types of Heat Exchangers ELO 1.1 – Describe the construction, effectiveness, and operation of the following types of heat exchangers and their components (tubes, tube sheets, baffles, and shells): tube and shell, and plate. ELO 1.1 5

6. © Copyright 2016Operator Generic Fundamentals Types of Heat Exchangers Tube and Shell 6 ELO 1.1 Figure: Tube and Shell Heat Exchanger

7. © Copyright 2016Operator Generic Fundamentals Types of Heat Exchangers Plate Heat Exchanger 7 ELO 1.1 Figure: Plate Heat Exchanger

8. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Applications Heat exchangers are found in most chemical or mechanical systems Common applications are: –Ventilation and air conditioning (HVAC) systems –Radiators on internal combustion engines –Boilers –Condensers –Preheaters or coolers In most cases: –high pressure fluid on tube side –low pressure fluid on shell side ELO 1.1 8

9. © Copyright 2016Operator Generic Fundamentals Preheaters and Feedwater Heaters Some heaters, such as feedwater, heat in stages verses all heat transfer in one large heat exchanger –Increases the plant's efficiency o Less overall increase in entropy –Minimizes thermal shock stress to components Extraction steam used as heat source to preheat the feedwater –Moisture must be removed to limit impingement damage to later stages –Recovering the heat from the extracted moisture increases the overall cycle efficiency ELO 1.1 9

10. © Copyright 2016Operator Generic Fundamentals Preheaters and Feedwater Heaters Below is an example of construction and internals of a U-tube feedwater heat exchanger used to preheat feedwater in the pump process 10 Figure: Feedwater Heater ELO 1.1

11. © Copyright 2016Operator Generic Fundamentals Radiator A heat exchanger is any device that transfers heat from one fluid to another Some equipment uses air-to-liquid heat exchangers An example of an air-to-liquid heat exchanger is a car radiator –Coolant flowing in engine picks up heat from engine block and carries it to radiator –Containment and room coolers are similar Hot coolant flows into tube side of radiator (heat exchanger) Relatively cool air flowing over the outside of the tubes picks up the heat, reducing temperature of coolant Fins on the outside of the tubes increase surface area for heat transfer and maximize heat transfer efficiency ELO 1.1 11

12. © Copyright 2016Operator Generic Fundamentals AC Evaporator and Condenser AC units contain at least two heat exchangers, usually called evaporator and condenser Refrigerant fluid flows into heat exchanger and transfers heat –cooling medium is commonly air or water In the condenser, the hot, high-pressure refrigerant gas condenses to a subcooled liquid In evaporator, subcooled refrigerant flows into heat exchanger –heat flow is reversed, cool refrigerant absorbs heat from hotter air flowing on the outside of tubes Cools the air and boils refrigerants ELO 1.1 12

13. © Copyright 2016Operator Generic Fundamentals Condenser Condenser is a type of heat exchanger used to condense a substance from a gaseous state to a liquid state by cooling Condenser removes latent heat from the condensing fluid and transfers it to coolant Normally, tube and shell heat exchanger serves as a condenser Baffles usually added at inlet to prevent tube impingement from incoming gas or steam Frequently use large steam condensers as heat sinks for steam system ELO 1.1 13

14. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Classification Parallel Flow 14 ELO 1.2 – Describe hot and cold fluid flow paths in the following types of heat exchangers: parallel flow, counter flow, and cross flow. Figure: Parallel-Flow Heat Exchanger ELO 1.2

15. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Classification Counter Flow ELO 1.2 Figure: Counter-Flow Heat Exchanger 15

16. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Classification Cross Flow ELO 1.2 Figure: Cross-Flow Heat Exchanger 16

17. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Comparison ELO 1.2 17

18. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Comparison ELO 1.2 18

19. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Comparison ELO 1.2 19

20. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Comparison ELO 1.2 20

21. © Copyright 2016Operator Generic Fundamentals Heat Transfer Rate Equations ELO 1.2 21

22. © Copyright 2016Operator Generic Fundamentals ELO 1.2 Classification by Flowpath What is the mass flow rate of cooling water? A.8.8 x 10 4 lbm/hr B.7.3 x 10 4 lbm/hr C.2.2 x 10 4 lbm/hr D.1.8 x 10 4 lbm/hr Correct answer is A. 22

23. © Copyright 2016Operator Generic Fundamentals ELO 1.2 Classification by Flowpath Knowledge Check – NRC Bank The rate of heat transfer between two liquids in a heat exchanger will increase if the… (Assume specific heats do not change.) A.inlet temperature of the hotter liquid decreases by 20°F. B.inlet temperature of the colder liquid increases by 20°F. C.flow rates of both liquids decrease by 10 percent. D.flow rates of both liquids increase by 10 percent. Correct answer is D. 23

24. © Copyright 2016Operator Generic Fundamentals Other Heat Exchanger Characteristics Most large heat exchangers are not purely parallel-flow, counter-flow, or cross-flow Combination types maximize heat exchanger efficiency Having two fluids pass each other several times within a single heat exchanger increases efficiency ELO 1.3 – Describe the difference between the following types of heat exchangers: single-pass versus multipass heat exchangers and regenerative versus nonregenerative heat exchangers. ELO 1.3 24

25. © Copyright 2016Operator Generic Fundamentals Other Heat Exchanger Characteristics Single-pass heat exchanger –Fluids pass each other once Multi-pass heat exchanger –Fluids pass each other more than once –Reverses flow in the tubes by use of one or more sets of U-bends in the tubes Baffles direct fluid back and forth across the tubes ELO 1.3 Figure: Single-Pass and Multi-pass Heat Exchangers 25

26. © Copyright 2016Operator Generic Fundamentals Other Heat Exchanger Characteristics Heat exchangers are classified by their function –Regenerative –Nonregenerative Regenerative heat exchanger –One fluid is both the cooling fluid and the cooled fluid –Usually found in high-temperature systems –Improves efficiency Nonregenerative heat exchanger –Hot fluid is cooled by fluid from a separate system –Energy (heat) removed is not returned to the system ELO 1.3 26

27. © Copyright 2016Operator Generic Fundamentals Regenerative and Nonregenerative Heat Exchanger Comparison ELO 1.3 Figure: Regenerative Heat ExchangerFigure: Non-regenerative Heat Exchanger 27

28. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Startup & Operation Startup Filled with fluid on both sides Cold fluid flow initiated first Hot fluid slowly initiated second to minimize thermal shock Vent air and noncondensable gases –can effectively reduce surface area and heat transfer coefficient ELO 1.4 – Describe the operation of a typical heat exchanger to include startup and shutdown, control of temperature, and the effects and control of fouling. ELO 1.4 28

29. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Startup & Operation Shutdown Hot fluid normally stopped first Cold fluid stopped Never isolate from overpressure protection (either a discharge valve left open or a relief valve installed) ELO 1.4 29

30. © Copyright 2016Operator Generic Fundamentals Temperature Control Control the flow of either the cooled fluid or cooling fluid Example – Reduce cooling water fluid flow –Heat transfer rate decreases o Hot side Outlet temperature (7) increases –Cold side Outlet temperature (6) also increases o Spends more time in H/X due to lowered flow rate ELO 1.4 Figure: Operating Water Cleanup System 30

31. © Copyright 2016Operator Generic Fundamentals Temperature Control Refer to the drawing: Valves are identical and are initially 50 percent open To raise the temperature at point 7, the operator can: –Cold Side (normal method) o Throttle closed on Valve D –Hot Side o Throttle open ANY valve on Hot Flow side –A, B, or C ELO 1.4 Figure: Operating Water Cleanup System 31

32. © Copyright 2016Operator Generic Fundamentals Fouling of Heat Exchange Surfaces Foreign material (algae, scale, or debris) accumulates in a heat exchanger Reduces conductive heat transfer coefficient Scale removed by –Hydrolancing –Chemical cleaning –Backwashing Maintaining minimum flow through heat exchanger can prevent deposits Turbulent flow aids in heat transfer by agitating laminar film Chemicals can be added ELO 1.4 32

33. © Copyright 2016Operator Generic Fundamentals Fouling of Heat Exchange Surfaces Scaling effect on Heat Transfer (Initial Effect): –Initially heat transfer rate decreases –Hot outlet temperature increases –Cold outlet temperature decreases Scaling effect on Heat Transfer (steady state to steady state): –Hot outlet increase results in Hot Inlet temperature increase –Heat transfer rate now increases (≈ back to original) –Results in cold outlet temperature increase (≈ back to original) –Approximately the same mass flow rates and Delta-T’s –Hot fluid inlet and outlet temperatures slightly elevated ELO 1.4 33

34. © Copyright 2016Operator Generic Fundamentals Knowledge Check – NRC Question Refer to the drawing of an operating lube oil heat exchanger below. Increasing the oil flow rate through the heat exchanger will cause the oil outlet temperature to _________ and the cooling water outlet temperature to __________. A.decrease; decrease B.decrease; increase C.increase; decrease D.increase; increase Correct answer is D. ELO 1.4 Heat Exchanger Startup & Operation 34

35. © Copyright 2016Operator Generic Fundamentals ELO 1.4 Heat Exchanger Startup & Operation Knowledge Check – NRC Question Refer to the drawing of an operating lube oil heat exchanger (see figure below). If mineral deposits accumulate on the inside of the cooling water tubes, cooling water outlet temperature will __________; and lube oil outlet temperature will __________. (Assume the lube oil and cooling water inlet temperatures and flow rates do not change.) A.increase; decrease B.increase; increase C.decrease; decrease D.decrease; increase Correct answer is D. 35

36. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Calculations ELO 1.5 – Given the necessary data, calculate flow rates and temperatures for various types of heat exchangers. ELO 1.5 36

37. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Calculations ELO 1.5 37

38. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Calculations Use the following table to determine flow or temperature difference of heat exchanger fluids: ELO 1.5 ActionFormula Determine heat transferred across heat exchanger to or from one of the fluids Determine log mean temperature difference between two fluids if necessary Once heat transfer is known, solve for flow or temperature difference of other fluid 38

39. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Calculations ELO 1.5 39

40. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Demonstration StepFormulaSolution ELO 1.5 40

41. © Copyright 2016Operator Generic Fundamentals Correct answer is A. A.126°F B.135°F C.147°F D.150°F ELO 1.5 Heat Exchanger Calculations 41

42. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Tube Failure Most common failure is a breach of the pressure boundary Tubes can be worn or eroded over time due to: –High flow rates –Particulate in the fluids passing through –Chemistry problems Vibration –Caused by irregular flow pattern or throttled flow ELO 1.6 – Explain the consequences of heat exchanger tube failure. ELO 1.6 42

43. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Failure Vibration could compromise seal between tubes and tube sheet or sealing surfaces between fluids Failure of the heat exchanger will allow two fluids to mix –Higher-pressure fluid forces into lower-pressure system Instrumentation shows an equalization of fluid temperatures at some mid-temperature Lower-pressure system level should increase Higher-pressure system level should decrease Depending on the fluid contents of either side –contamination of one side can occur ELO 1.6 43

44. © Copyright 2016Operator Generic Fundamentals Heat Exchanger Failure Example Refer to the drawing of an operating cooling water system. What occurs when a tube fails in the heat exchanger? Based on system pressures/temperatures: –HP pressure decreases (tube side) –LP pressure increases (shell side) –Surge tank level decreases –LP fluid temperature increases ELO 1.6 Figure: Cooling Water System 44

45. © Copyright 2016Operator Generic Fundamentals ELO 1.6 Heat Exchanger Failure Knowledge Check – NRC Bank Borated water is flowing through the tubes of a heat exchanger being cooled by fresh water. The shell-side pressure is less than tube-side pressure. What will occur as a result of a tube failure? A.Shell-side pressure will increase and the borated water system will be diluted. B.Shell-side pressure will decrease and the borated water inventory will be depleted. C.Shell-side pressure will increase and the borated water inventory will be depleted. D.Shell-side pressure will decrease and the borated water system will be diluted. Correct answer is C. 45

46. © Copyright 2016Operator Generic Fundamentals Condenser Construction and Operation 2.1State the purpose of a condenser. 2.2State the definitions of hotwell and condensate depression. 2.3State the reason(s) why condensers in large steam cycles operate at a vacuum. 2.4State the definition of thermal shock. 2.5Describe the relationship between condenser vacuum and backpressure. 2.6Explain the process of forming a vacuum within a condenser. TLO 2 – Describe the purpose, construction, and principles of operation of condensers. TLO 2 46

47. © Copyright 2016Operator Generic Fundamentals Purpose of a Condenser Main Condenser Purpose of the condenser is to: –Provide a heat sink for turbines to exhaust to give up latent heat of vaporization –Operate in a vacuum to provide lowest heat sink o maximizes available heat energy transfer –Deareate condensate and feedwater o improves corrosion protection ELO 2.1 – State the purpose of a condenser. ELO 2.1 47

48. © Copyright 2016Operator Generic Fundamentals Purpose of a Condenser Gives up latent heat of vaporization –Converts used steam into water for return to S/G –Increases cycle's efficiency, allowing largest possible ΔT and ΔP between heat source and heat sink ELO 2.1 Figure: Single-Pass Condenser 48

49. © Copyright 2016Operator Generic Fundamentals ELO 2.1 Purpose of a Condenser Called latent heat of condensation –Or rejection of latent heat of vaporization Specific volume decreases drastically –Creates a low pressure, maintaining vacuum Increases plant efficiency Figure: Condenser 49

50. © Copyright 2016Operator Generic Fundamentals ELO 2.1 Purpose of a Condenser Thermodynamic Cycle Liquid delivered to condensate pump, then feed pump where its pressure is raised (point 1) to the saturation pressure corresponding to steam generator temperature High-pressure liquid is delivered to steam generator where cycle is repeated Figure: Thermodynamic Cycle 50

51. © Copyright 2016Operator Generic Fundamentals Purpose of a Condenser Condensed steam (saturated liquid) continues to transfer heat as it falls to the bottom of the condenser, called subcooling –Subcooling prevents condensate pump cavitation –Too much subcooling lowers efficiency Typically uses a single-pass, cross-flow condenser ELO 2.1 51

52. © Copyright 2016Operator Generic Fundamentals Condenser Terms As steam comes in contact with tubes, it cools and condenses Series of baffles redirects steam to minimize direct impingement on the cooling water tubes Condensed steam falls to the bottom of condenser Bottom area is a reservoir where condensate collects and is called the hotwell ELO 2.2 – State the definitions of hotwell and condensate depression. Figure: Condenser Cross-Section ELO 2.2 52

53. © Copyright 2016Operator Generic Fundamentals Condensate Depression As the condensate falls towards the hotwell, it subcools –comes in contact with tubes lower in the condenser Amount of subcooling is “condensate depression” T SAT – T HOTWELL = the amount of condensate depression Figure: T-s Diagram for Typical Condenser ELO 2.2 53

54. © Copyright 2016Operator Generic Fundamentals Condenser Vacuum Steam's latent heat of condensation is passed to water flowing through tubes Condenser usually operated at a vacuum Vacuum helps increase plant efficiency by extracting more work from the turbine ELO 2.3 – State the reason(s) why condensers in large steam cycles operate at a vacuum and the impact non-condensable gasses have on vacuum. ELO 2.3 54

55. © Copyright 2016Operator Generic Fundamentals Condenser Vacuum Steam turbines designed to exhaust into a condenser that operates within a specific vacuum range If pressure increases above these limits –physical damage will occur to turbine blades When exhausted steam is condensed, its specific volume decreases –helps maintain vacuum If condensate level is allowed to rise over lower tubes of condenser, fewer tubes are exposed for heat transfer –reducing heat transfer area Temperature and flow rate of cooling water through condenser control temperature of condensate –This in turn controls saturation pressure (vacuum) of condenser ELO 2.3 55

56. © Copyright 2016Operator Generic Fundamentals Condenser & Noncondensable Gases If noncondensable gases are allowed to build up in condenser –vacuum decreases and saturation temperature at which steam condenses increases Noncondensable gases also blanket tubes of condenser –reducing surface area for heat transfer in condenser Reduction in heat transfer surface has same effect as a reduction in cooling water flow ELO 2.3 56

57. © Copyright 2016Operator Generic Fundamentals Vacuum & Noncondensable Gases Condenser vacuum should be maintained as close to 29 inches of Mercury (Hg) as practical Allows maximum expansion of steam and therefore maximum work If condenser perfectly airtight and no air or noncondensable gases present in exhaust steam –only necessary to condense steam and remove condensate to create and maintain vacuum Figure: Condenser Cross-Section ELO 2.3 57

58. © Copyright 2016Operator Generic Fundamentals Vacuum & Noncondensable Gases Sudden reduction in steam volume as it condenses creates a vacuum –Pumping water from condenser as fast as it forms maintains vacuum Not possible to prevent entrance of air and other noncondensable gases into condenser Some method also needed to create initial vacuum in condenser –Necessitates use of an air ejector or vacuum pump to establish and help maintain condenser vacuum ELO 2.3 58

59. © Copyright 2016Operator Generic Fundamentals ELO 2.3 Condenser Vacuum Knowledge Check During normal nuclear power plant operation, a main condenser develops an air leak that decreases vacuum at a rate of 1 inch of Hg/minute. Which of the following will increase because of this condition? A.Steam cycle efficiency. B.Main turbine work output. C.Condenser hotwell temperature D.Low-pressure turbine exhaust steam moisture content. Correct answer is C. 59

60. © Copyright 2016Operator Generic Fundamentals Thermal Shock Thermal shock is the severe stress produced in a material upon experiencing a sudden, unequally distributed change in temperature Heat exchangers and condensers experience pressure stress and thermal stress due to function of transferring heat To reduce effects of these stresses –condensers should be as close as possible to operating temperatures prior to admitting steam from main turbine If equipment is not properly preheated, severe damage can occur to condenser tubes and the turbine ELO 2.4 – State the definition of thermal shock. ELO 2.4 60

61. © Copyright 2016Operator Generic Fundamentals Thermal Shock Large Delta-T’s in a condenser are good from a thermodynamic perspective However, they should be controlled in the system to prevent thermal shock to components Prevention Hotter fluids or vapors should be slowly admitted When out of service, heat exchangers are maintained, filled, and pressurized –Condensers steam side vented, waterside filled ELO 2.4 61

62. © Copyright 2016Operator Generic Fundamentals Thermal Shock Prevention Main condensers must be at operating pressures (vacuum) prior to admitting steam Colder fluid should be supplied to heat exchanger first, followed by hotter fluid When securing a heat exchanger or condenser hot fluid, vapor is stopped first Colder fluid is allowed to operate for a period of time to cool down component(s) and reduce stress ELO 2.4 62

63. © Copyright 2016Operator Generic Fundamentals Thermal Shock Heat exchangers and condensers should not be isolated in such a manner that they do not have relief valve protection Liquid isolated within the heat exchanger could warm up due to surrounding air temperature Increased temperature would lead to expansion of liquid and damage to heat exchanger if not protected from overpressure ELO 2.4 63

64. © Copyright 2016Operator Generic Fundamentals ELO 2.4 Thermal Shock Knowledge Check The major thermodynamic concern resulting from rapidly cooling a reactor vessel is... A.thermal shock. B.stress corrosion. C.loss of shutdown margin. D.loss of subcooling margin. Correct answer is A. 64

65. © Copyright 2016Operator Generic Fundamentals Vacuum Versus Backpressure Pressure and Vacuum Relationship If pressure is below that of atmosphere as in case of a condenser, it is a vacuum Vacuum, although a negative pressure, is normally expressed as a positive value ELO 2.5 – Describe the relationship between condenser vacuum and backpressure. ELO 2.5 65

66. © Copyright 2016Operator Generic Fundamentals Vacuum Versus Backpressure Pressure and Vacuum Relationship Figure: Comparison of Pressure Ranges ELO 2.5 66 Vacuum Absolute

67. © Copyright 2016Operator Generic Fundamentals Vacuum Versus Backpressure ELO 2.5 67

68. © Copyright 2016Operator Generic Fundamentals Vacuum Versus Backpressure Table shows the relationship between pressure measurements associated with a condenser 29.9 inches of Hg pressure equals zero (0) inches of mercury vacuum (HgV) and zero (0) inches of Hg equals 29.9 inches of HgV PSIAPSIGInches of HgVInches of Hgabs 14.70029.90 13.72.0327.87 12.7-2.04.0625.84 11.7-3.06.0923.81 ELO 2.5 68

69. © Copyright 2016Operator Generic Fundamentals Vacuum Versus Backpressure Given that a condenser pressure is 3 inches of Hg, determine the corresponding vacuum by: 29.9 – 3 = 26.9 inches of Hg vacuum ELO 2.5 69

70. © Copyright 2016Operator Generic Fundamentals Drawing a Vacuum To prepare plant for startup, a vacuum must be drawn in the main condenser –Allows recirculation of feedwater and condensate in order to clean up and deaerate these systems –Allows warming of the main turbine Vacuum is a condition where all molecules are removed Allows steam cycle to exhaust to lowest possible heat sink –providing largest enthalpy change through the main turbine ELO 2.6 – Explain the process of forming a vacuum within a condenser. ELO 2.6 70

71. © Copyright 2016Operator Generic Fundamentals Drawing a Vacuum Consists of isolating air in-leakage paths, establishing cooling water flow, then removing air from the condenser shell Vacuum normally drawn using vacuum pumps or steam jet air ejectors Air removal during operation is essential for efficient operation If air leaks into the condenser, pressure increases, temperature increases, and plant efficiency decreases because the turbine exhaust enthalpy increases ELO 2.6 71

72. © Copyright 2016Operator Generic Fundamentals Action StepHowDiscussion Establish cooling flow Startup support cooling systems Startup circulation water system Startup condensate system Various systems provide cooling for components necessary for vacuum pull (condensate pumps, air compressors, mechanical vacuum pumps) Isolate all air inleakage paths to the main condenser Complete valve lineup checks Close vacuum breakers Establish steam seal on turbines All possible leakage paths must be isolated to prevent loss of condenser pressure and temperature control. Air leakage across turbine shaft seals is removed via gland exhaust system. Establish turbine seals Startup steam sealing system Startup gland exhaust system Turbine shafts are sealed using labyrinth seals and low-pressure steam to prevent high-pressure steam from leaking out and air from leaking in. Remove air from the condenser Startup the mechanical vacuum pump (also known as a hogger) Shift to the air ejectors when vacuum reaches approximately 26 inches of HgV Mechanical vacuum pump removes air out of main condenser. As air molecules are removed, pressure decreases. Drawing a Vacuum ELO 2.6 72

73. © Copyright 2016Operator Generic Fundamentals NRC KA to ELO Tie KA #KA StatementROSRO K1.01Startup/shutdown of a heat exchanger2.12.3 K1.02Proper filling of a shell-and-tube heat exchanger2.12.3 K1.03Basic heat transfer in a heat exchanger2.22.3 K1.04 Effects of heat exchanger flow rates that are too high or too low and methods of proper flow adjustment2.52.7 K1.05Flow paths for the heat exchanger (counterflow and U-types)1.81.9 K1.06Components of a heat exchanger (shells, tubes, plates, etc.)1.71.9 K1.07Control of heat exchanger temperatures2.42.6 K1.08Relationship between flow rates and temperatures2.4 K1.09Definition of thermal shock2.8 K1.10Principle of operation of condensers2.32.4 K1.11Relationship between condenser vacuum and backpressure2.1 K1.12Effects of tube fouling and tube failure scaling on heat exchanger operation2.52.7 K1.13Consequences of heat exchanger tube failure2.82.9 K1.14Reasons for non-condensable gas removal2.42.6 73