Midterms Flashcards
(100 cards)
1
Q
formation and accumulation of bubbles around a pump impeller.
A
Cavitation
2
Q
when the pressure of a liquid at a constant temperature falls below its saturated vapor pressure point
A
Cavitation
3
Q
Cavitation can occur when the Net Positive Suction Head Available (NPSHa) is ____ the Net Positive Suction Head Required (NPSHr
A
Lower
4
Q
Common causes of flow disruption that result in cavitation:
A
Excessively long inlet piping
Higher than expected fluid viscosity
Clogged inlet
Clogged filters and strainers
Poorly specified pump
5
Q
How to recognize pump cavitation
A
Cavitation sounds like marbles or gravel circulating through the pump, pipes, or hoses.
6
Q
Typical indications of cavitation:
A
Noise, Vibration, Seal/bearing failure, Impeller erosion, Higher than usual power consumption.
7
Q
energy that pushes the liquid through the pump
A
Net Positive Suction Head (NPSH)
8
Q
When NPSH drops, ________ occurs.
A
Cavitation
9
Q
A measure of the absolute pressure present in a liquid.
A
NPSH
10
Q
- value that expresses the absolute pressure acting on a liquid as it enters the pump.
A
NPSHa
11
Q
operate without experiencing damaging cavitation and a dramatic reduction in pumping production.
A
NPSHr
12
Q
Expresses the minimum absolute pressure that must be acting on a liquid as it enters the pump impeller to avoid excessive cavitation and degradation of pump performance.
A
NPSHr
13
Q
Occurs when a pressure of a liquid droos below its vapor pressure
A
Cavitations
14
Q
NPSHa should be ____ than NPSHr
A
Higher/greater
15
Q
Transfer of heat from lower-temp substance to a higher temp usung a refrigeration cycle
A
Refrigeration cycle
16
Q
Primary purpose of ref cycle
A
Lower the temp of an area or substance
17
Q
where the working fluid absorbs the heat from the surrounding at a low temperature and rejects the heat to the atmosphere at a higher temperature.
A
Refrigeration cycle
18
Q
In ref cycle, heat flows from
A
Low temp to high temp
19
Q
Refrigeration cycle’s mission
A
heat absorption and heat rejection.
20
Q
The refrigeration cycle, sometimes called a
A
Heat pump cycle
21
Q
can be thought of as the heart of the process in refrigeration cycle
A
Compressor
22
Q
refrigeration cycle consists of just 4 basic components to complete the circuit:
A
Compressor
Condenser
Restriction
Evaporator
23
Q
It acts like a pump to create circulation by compressing the refrigerant gas.
A
Compressor
24
Q
Primary function of compressor
A
Compress low pressure and low temp to high pressure and high temp
25
cools and condenses the refrigerant gas coming from the compressor into a vapor and finally into a liquid.
Condenser
26
restricts the liquid refrigerant flow and creates a pressure difference between itself and the evaporator
Restriction
27
evaporates the liquid refrigerant into a vapor and then into a gas before it gets back to the compressor.
Evporator
28
This is where the refrigerant absorbs heat from the refrigerate area
Evaporator
29
Refrigerant can be
GAS, VAPOUR and a LIQUID.
30
Pump curve aka
Performance curve or pump characteristic curve
31
Pump curve is a graphical representation that
Provides info about performance of centrifugal pump or any pump
32
This helps in understanding how a pump behaves under different operating conditions
Pump curve
33
tell you how much net positive suction head the pump requires
Pump curves
34
The pump’s operating “sweet spot,” is also called as
best efficiency point (BEP)
35
best efficiency point (BEP), is generally located ____
Near the middle of the curve
36
Pumps are the _____ when they can run near their BEP, as determined by the manufacturer.
most efficient and have their highest life expectancy
37
Typically, the area on the curve between 70 and 120 percent of the BEP is known as
preferred operating region (POR)
38
In general, the _____ the specific speed of an impeller, the _____ the curve will be.
Lower, flatter
39
Usually represented on the x-axis of the graph on pump curve
Flow Rate (Q)
40
Volume of fluid (such as water) that the pump can move per unit of time
Flow rate
41
Represented by y-axis of the graph
Head (H)
42
energy added to the fluid by the pump
Head
43
Indicates the effectiveness of the pump in converting input energy into hydraulic energy
Efficiency (n)
44
By comparing ____ and ____, engineers cam find operating point at which the pump will perform optimally
System curve and pump curve
45
Point along a pump performance curve where efficiency is the highest
Best efficiency point (BEP)
46
Best Efficiency Point is where the ________ peaks
Pump efficiency
47
How to increase suction head available
1. Raise and maintain tank liquid level.
2. Elevate supply tank.
3. Reduce piping losses from too many fittings or too small diameter.
4.Replace collapsed or compromised components.
5. Clear solids from inside of pipes.
6. Replace corroded pipe.
7. Check for a gasket protruding into piping.
48
A good rule-of-thumb is to require that NPSHa be _____ than NPSHr by at least ____ and not less than ____.
Greater, 10%, 5 Ft
49
Used in industrial settings to power pneumatic instruments and control systems
Instrument air
50
Clean, dry, oil-free compressed air used in industrial settings to power pneumatic instruments
Instrument air
51
purified to remove contaminants and moisture, preventing damage and corrosion and distributed thru network of pipes maintaining consistent pressure
Instrument air
52
extremely clean supply of compressed air that is free from contaminates such as moisture & particulates.
Instrument air
53
Standard Air Temperature & Pressure (STP) is measured as:
Pressure=14.7 Psia
Temperature=68 F
Relative Humidity=40%
54
Desalination is also called as
desalting
55
removal of dissolved salts from seawater and brackish waster to make it safe for drinking and industrial use
Desalination
56
Desalination occurs naturally during the ____
water cycle: The evaporation of seawater leaves salt behind and forms clouds that give rise to rain.
57
residue resulting from the desalination
Brine
58
Desalination two methods
- Reverse Osmosis
- Multi-stage flash (MSF) or Multi-effect distillation (MED)
59
Explain the Reverse osmosis method
High pressure forces water thru semi permeable membrane, which allows water molecules to pass and block the salts and impurities
60
Purified water.in RO is ___ while ___ is disposed of
Permeate, concentrated brine (or any rejected salty water)
61
Explain multi stage flash or multi effect distillation
Use heat to evaporate water, leaving salts behind. Used in large-scale plants
62
Sieve trays rely on the flow of vapors through the _____ and cannot operate _____
holes to hold the liquid on the tray, at very low vapor rates.
63
Components used in distillation columns for separating liquid mixtures based on their boiling points
Sieve trays, valve trays, and bubble cap trays
64
Differentiate sieve, valve, and bubble cap trays
- Sieve trays consists of perforated plates with holes that allows vapor to rise and contact the liquid. Simple, cost-effective, and work well for non-foaming systems.
- Valve trays have movable valves on tray surface, versatile, and can handle wide range of vapor and liquid loads
- Bubble cap trays feature indiv caps or covers on each tray hole. Provide excellent separation esp in foamy but complex and costly.
65
Packed column vs plate column
Packed - for smaller diameter, low-capacity operation, foaming systems and corrosive substances
Plate - large diameters, high number of stages, more accessible for maintenance
66
Safety vs. process control
- Safety focuses on protecting personnel, equipment, and environment from potential hazards.
- Process control involves monitoring the variables that affect the production process to ensure consistent and efficient operations
67
A _____ is a type of valve that can start, stop, and regulate the flow of fluid from one point to another.
Throttling valve
68
Process of partially closing or opening a ctrl valve to regulate the flow rate of liquids
Valve throttling
69
A ____ contains a rotating impeller that creates a vacuum that helps in moving fluids.
dynamic pump
70
Pumps that can handle highly viscous fluids
Positive disp pump
71
Compressor choke or ??
Stonewall
72
unstable operating condition, which occurs when the compressor is operating at low discharge pressure and high flow rate. At this point, no more flow can pass through the compressor, causing high frequency and low amplitude vibration of the rotor blades or stator vanes.
Compressor choke or stone wall
73
unstable condition of compressor that causes the erratic compressor performance.
Surge
74
the task of __ to detect and automatically compensate for the potential disturbance by the surge condition.
Anti-surge system
75
Fans, blowers, compressors
- Fan used to move fluid or air, pressure rise req is small
- Blower is a machine to move air at moderate pressure
- Compressor is a machine that reduces the volume of a gas with high pressure. (More on increasing the pressure of gas rather than moving it)
76
conducted after completion of Conceptual Design or Feasibility Study. At this stage, before the start of EPC, various studies take place to figure out technical issues and estimate rough investment cost.
FEED (Front-End Engineering Design)
77
EPC means
Engineering, Procurement and Construction
78
contracting agreement where the contractor is responsible for all the engineering services on a project
Engineering, Procurement and Construction
79
Incoterms or
International Commercial Terms
80
Set of standardized trade terms established by the ICC (international chamber of commerce), define responsibilities, obligations with shipment and delivery between buyers and seller internationally
Incoterms (Int. Commercial Terms)
81
define responsibilities, obligations with shipment and delivery between buyers and seller internationally
Incoterms (Int. Commercial Terms)
82
Basic legislation on wastewater treatment raisung the standard values of 6 parameters
DAO 2016-08 (DENR administrative order)
83
effective technology for disposing of gases that cannot be used otherwise
Flare
84
device used to safely dispose of unwanted or excess gases and liquids from normal, unplanned or upset conditions during process operations in CPI sites.
Flare
85
Flaring is done by
burning off the gas or liquid into the atmosphere.
86
Design Pressure vs MAWP (max allowable working pressure)
design pressure is always calculated while designing the equipment, whereas MAWP is measured after completing it
87
The design pressure should be _____ than MAWP.
equal to or less
88
Serves as support the tubes in the proper position during assembly and operation and prevent vibration of the tubes
Baffles
89
sound, usually of a characteristic pitch ranging from a low rumble to a piercing scream, caused by the shell side fluid flowing through the bundle.
Acoustic vibration
90
clearance maintained between the maximum water level and the roof slab.
Free board
91
space kept between the top of water level and the bottom of the roof slab of the water tank
Free board
92
Deadwood example
ladders, supports, bolts, nuts, and channels
93
any part of the interior of the tank that reduces or adds to the volume.
Deadwood
94
A butterfly check valve is known as a dual plate check valve, folding disc check valve, double-disc, or splits disc check valve.
95
As the name suggests, two halves of the disk move towards the centerline with the forward flow, and with reverse flow two halves open and rest on the seat to close the flow.
butterfly check valve
96
produces a violent slamming that physically moves the pipe and causes a loud banging noise.
Water hammer
97
Water hammer aka
Hydraulic shock or fluid hammer
98
Occurs when there is a sudden change of velocity within a pipe
Water hammer
99
portion of the condensed overhead liquid product from a distillation tower that is returned to the upper part of the tower
Reflux
100
metabolic pathway that converts glucose into pyruvate.
Gycolysis
