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Process Design and Safety > Final > Flashcards

Final Flashcards

1
Q

What is FCI

A

Fixed Capital Investment

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2
Q

What is TCI

A

Total Capital Investment

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3
Q

What is Direct Production Cost part of?

A

Product Cost (C)

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4
Q

Do you get back the money associated to depreciation?

A

No

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5
Q

Can your cumulative cash position be negative?

A

Yes

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6
Q

The cost of installing a pump (not purchasing it) is

A

Part of Direct Investment Cost

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7
Q

The Marshall and Swift index is used to adjust

A

Capital Cost by time

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8
Q

A pump has a cost of $14,000 and a scrap value of $2,000. What is the total depreciation?

A

$14,000 - $2,000 = $12,000

Cost - scrap value = depreciation

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9
Q

A plant cost is $3,000,000 in 2007. What is the cost in 2018 if the M&S indices are 1452.3 in 2007 and 1955.8 in 2018?

A

$3,000,000(1955.8/1452.3)=$4,040,074

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10
Q

A plant has a cost of $300,000 for a capacity of 100 ton/day. What is the cost of the plant for a capacity of 230 ton/day if the power is x=0.6?

A

$300,000(230/100)^.6 = $494,490

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11
Q

What is depreciation?

A

Loss of equipment value

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12
Q

What is straight line depreciation?

A

Equal depreciation each year

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13
Q

Depreciation does not last for as long as the plant does what?

A

Operates

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14
Q

Depreciation does/does not last forever?

A

Does not

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15
Q

(T/F) Depreciation lasts only one or two year?

A

False

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16
Q

(T/F) Depreciation is mandatory?

A

False

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17
Q

MACRS depreciation is what?

A

Double decline followed by straight line depreciation

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18
Q

When the cost exponent of capacity is less than 1, two equipment of equal size will cost what?

A

More than one of twice the size

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19
Q

What is money spent today to take raw material and covert it to a unit of product called?

A

Product cost

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20
Q

A pump has a cost of $14,000 and a scrap value of $2000. What is the depreciation using straight line method over 10 years?

A

($14,000-$2,000)/10 = $1,200

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21
Q

A pump has a cost of $14,000 and a scrap value of $2,000. What is the first year depreciation using double decline method calculated for a total of 10 years?

A

$12,000(1-(2/10))^1 = $9,600

$12,000 - $9,600 = $2,400

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22
Q

What is return of investment?

A

Net annual profit divided by TCI

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23
Q

What is the value today of future money?

A

Present worth

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24
Q

What is POT?

A

Pay Out Time

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25
Q

What is the present value of all net profits in the future minus TCI?

A

Net Present Worth

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26
Q

Why is ROI a disadvantage?

A

It considers all future net profit being the same value

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27
Q

What depends heavily on the interest rate used?

A

Net Present Worth

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28
Q

What do we call the interest rate that makes NPW=0

A

Effective

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29
Q

What is the time needed to get the TCI back?

A

Payout time

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30
Q

What reduces energy consumption?

A

Heat integration

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31
Q

What converts many hot or cold stream curves into one hot and one cold, respectively?

A

Composite curves

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32
Q

What is Pinch?

A

The smallest delta T than can take place anywhere

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33
Q

What should not be transferred across the pinch?

A

Heat

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34
Q

What is obtained by overlapping hot and cold composite curves?

A

Minimum heating utility

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35
Q

What increases cold utility by the same amount?

A

Increasing heating utility

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36
Q

What is spread over the number of years the IRS determines?

A

Depreciation

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37
Q

A pump has a cost of $14,000 and a scrap value of $2,000. What is the second year depreciation using double decline method for a total of 10 years?

A

$12,000(1-(2/10))^2=$7,680 second year
$12,000(1-(2/10))^1=$9,600 first year
$9,600-$7,680=$1,920

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38
Q

The net profit of an investment is $200,000/year for 10 years. does the ROI change if the net profit is also $200,000/15 years?

A

ROI = Net Profit/ TCI
Net profit is $200,000/year for 10 years = $2,000,000
Net profit is $200,000/year for 15 years = $3,000,000
Yes it will increase

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39
Q

The net profit of an investment is $200,000 /year, the capital is $1,000,000. What is the POT?

A

$1,000,000/($200,000/year)=5 years

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40
Q

What have rotating gears, lobes, or screws?

A

Rotary pumps

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41
Q

What pump does not have a large pressure head?

A

Centrifugal pumps

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42
Q

What is defined as discharge pressure minus suction pressure?

A

Total Dynamic Head (TDH)

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43
Q

What is equal to the volumetric flowrate * the total dynamic head?
?=Q*TDH

A

Hydraulic power of a pump

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44
Q

What is the difference between suction head and vapor pressure head?

A

NPHSA

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45
Q

What is provided by the manufacturer of a pump?

A

NPHSR

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46
Q

NPHSR has to be (greater/smaller) than NPHSA.

A

Smaller

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47
Q

Two equal pumps in a series have what?

A

Double the head

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48
Q

What has smaller head than one pump?

A

Two equal pumps in parallel

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49
Q

What can happen if NPHSA is zero?

A

The pump can cavitate

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50
Q

What prevent flow reversal?

A

Check valves

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51
Q

What are usually not used for control?

A

Gate valves

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52
Q

What have large pressure drops?

A

Control valves

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53
Q

Closing a control valve (increases/decreases) the pressure drop in a system.

A

Increases

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54
Q

Do rotary pumps have reduced outlet pressure?

A

No

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55
Q

Do rotary pumps have rotating casings?

A

No

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56
Q

Do rotary pumps have cavitation problems?

A

No

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57
Q

Do Centrifugal pumps work well with viscous fluids?

A

No

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58
Q

Can centrifugal pumps only handle small flows?

A

No

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59
Q

Do centrifugal pumps cavitate when the flow is too large?

A

No

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60
Q

What is discharge pressure minus suction pressure?

A

Total dynamic head

61
Q

NPHSA is define as what?

A

Suction head minus vapor pressure

62
Q

In flash design, the balance of forces is considered what?

A

Gravity vs drag forces vs buoyancy vs viscosity

63
Q

The velocity used to obtain a column diameter is smaller/larger than the flooding velocity?

A

Smaller

64
Q

The formula g(delta z) + delta p/rho + (v2^2-v1^2)/2 = delta W - (sum of friction losses) is used for what?

A

Liquids

65
Q

What is a rapid and uniform expansion?

A

Explosion

66
Q

What is comprised of an initial system boundary and an expanding shock wave?

A

An explosion

67
Q

When does the expansion end?

A

When the pressure of the final system is P = 1 atm

68
Q

What is the limit for the expansion velocity?

A

The speed of sound

69
Q

What can be achieved only when the initial pressure at detonation is sufficiently high?

A

The expanding shockwave reaches the speed of sound

70
Q

The first law describes the rate change of what?

A

Total Energy (internal and external) of the system

71
Q

What is the rate change of total energy of the system equal to?

A 
Energy added/subtracted associated with mass entering/leaving the system
\+
Heat added
\+
Shaft work
-
Expansion work
\+
Work done by fluid entering or leaving the system
72
Q

The second law of thermodynamics is related to what?

A

Entropy change with time

73
Q

In a closed system, the final mass is equal to what?

A

The initial mass

74
Q

With closed systems, explosions are considered adiabatic and the heat terms go to what?

A

Zero

75
Q

A closed and adiabatic system reduces the first law to what?

A

(DU/dt) + (M d/dt (v^2/2 + psi) = -P dV/dt

76
Q

In closed and adiabatic systems the Second Law is reduced to what?

A

DS/dt = S gen

77
Q

why does entropy generation only occur at the boundary?

A

Explosions are uniform

78
Q

Because entropy only occurs at the boundary what can be neglected?

A

Entropy

79
Q

Neglecting entropy reduces the second law to what?

A

DS/dt = 0

80
Q

Because the speed of the system and its potential energy does not change, what term in the first law goes to zero?

A

D/dt (M(v^2/2 + psi))

81
Q

The final representation of the first flaw when studying explosions is what?

A

DU/dt = -P dV/dt

82
Q

If you integrate the final first law equation from t =0 to t = final time what happens?

A

First Law becomes

M( U at final pressure and temperature - U at initial pressure and temp)
=
W
=
- integral PdV
83
Q

If you integrate the final second law obtained when studying explosions what do you get (from t=0 to t=tf)?

A

Entropy at initial pressure and temperature
=
0

84
Q

What are some explosion and fire prevention methods used in design?

A

Explosion resistant equipment
Sprinkler Systems
Static electricity preventing materials

85
Q

What are some explosion and fire prevention methods used in operation?

A 
Inerting
-Vaccum Purging
-Pressure Purging
-Sweep-Through Purging
Static Electricity Control
-Grounding
-Increasing conductivity in joints with additives
86
Q

Cracks in equipment are preferred where on a unit?

A

Top and bottom, not sides

87
Q

Double walls may be used for what?

A

Corrosive materials

88
Q

What can build up in pipes that have the potential to cause a fire or explosion?

A

static electricity

89
Q

What is inerting?

A

using N2 or CO2 to reduce O2 concentrations in a vessel

90
Q

Reducing oxygen levels reduces what?

A

the risk of explosions

91
Q

If the vessel will contain gas, when should you perform inerting?

A

prior to loading the gas

92
Q

If the vessel will contain liquid, when should you perform interting?

A

prior to filling with liquid and then continue to purge on vapor phase

93
Q

What is needed during inerting?

A

an oxygen analyzer

94
Q

What does LOC and MOC stand for?

A

Limiting Oxygen Concentration

Minimum Oxygen Concentration

95
Q

Having too much oxygen can do what?

A

limit explosions

96
Q

What oxygen concentration should you use as a rule of thumb if you do not have data?

A

10 mol%

97
Q

What are the steps of vacuum purging?

A

1 Draw some vacuum to a pressure that will not make the vessel implode
2 Replenish with inert
3 Repeat until the oxygen is at the desired level

98
Q

Does vacuum purging require the pressure to be zero?

A

No

99
Q

What is inert is usually used in vacuum purging?

A

N2

100
Q

What is usually the desired pressure level of the oxygen during vacuum purging?

A

atmospheric

101
Q

During vacuum purging what do we assume to simplify calculations?

A

that temperature stays the same and Z=1

102
Q

How do you calculate the moles of O2 at high pressure?

A

(n oxygen)H = (nH)(yO2) original

103
Q

How do you calculate the moles of O2 at low pressure?

A

(n oxygen)L = (nL)(yO2) original

104
Q

After N2 is added the pressure is (low/high).

A

high

105
Q

How do you calculate the mole fraction of oxygen after nitrogen is added and the pressure is higher?

A

yO2 = (noxygen)L / nH

106
Q

How do you calculate nH? (total number of moles at high pressure)

A

nH = (PH * V) / (ZH * R * T)

107
Q

How do you calculate nL? (total number of moles at low pressure)?

A

nL = (PL * V) / (ZL * R * T)

108
Q

for k times that vacuum purging is repeated what is the general equation?

A

yO2 = yO2 original * (nL/nH)^k

109
Q

What are the steps for pressure pruging?

A

1 pressurize the vessel with inert to a value admissible
2 let the pressure go down
3 repeat until the oxygen is at the desired level

110
Q

In what type of purging do we treat the original state as the high pressure one and PL is the initial pressure (usually atmospheric)?

A

Pressure purging

111
Q

what formulas are used for pressure purging?

A

yO2 original = 0.21 PL/PH = 0.21 Patm/PH

(yO2 after being repeated k times)/yO2 original = (Patm/PH)^k

112
Q

In what type of purging do you add inert into one opening and let the gas leave the vessel from another?

A

Sweep-through

113
Q

What equation do you use for sweep-trough purging?

A

V dC/dt = Co (molecules going in) * Qv - C (molecules going out) *Qv

this is a mass balance

114
Q

After integrating the sweep-through mass balance what equation do you get?

A

Q*t= V ln [(C (at t=0) -Co)/(C(t) - Co)]

115
Q

Co needs to be what to avoid taking a long time to purge?

A

small

116
Q

What is Q times t?

A

amount of mass

117
Q

Piping and Instrument Diagrams show what?

A

all piping connecting equipment
all valves
all instrumentation (measuring, transmitters, controllers, actuators)

118
Q

The first letter of an instrumentation indicator represents what?

A

the measured variable

119
Q

the measured variable can be what?

A

Pressure
Level
Flow
Temperature

120
Q

The letters following the first are used to what?

A

designate the function of the component or to modify the meaning of the first letter

121
Q

Letters other than the first can represent what?

A

Indicator
Recorder
Controller
Transmitter

122
Q

What is the meaning when there is no line on the instrumentation circle?

A

The instrument is mounted in the field near the process (close to the operator)

123
Q

What is the meaning when there is a solid line on the instrumentation circle?

A

The instrument is mounted in the control room (accessible to the operator)

124
Q

What does it mean when the is a dotted line on the instrumentation circle?

A

the instrument is mounted out of sight (not accessible to the operator)

125
Q

Piping is indicated how on a PID?

A

thick line

126
Q

A process is indicated how on a PID?

A

thinner line

127
Q

electrical signals are indicated how?

A

dashed line

128
Q

pneumatic signals are indicated how?

A

double slashes along the line

129
Q

data links are indicated how?

A

open circles along the line

130
Q

capillary tubing for filled systems are indicated how?

A

X’s along the line

131
Q

hydraulic signal lines are indicated how?

A

L’s along the line

132
Q

How are guided electromagnetic or sonic signals indicated?

A

hourglass like shapes (slanted)

133
Q

What are angle valves used for?

A

high pressure drops

134
Q

What kind of flare limits radiation effects?

A

vertical; tall

135
Q

Why don’t we use horizontal flares?

A

take up too much space

plumes form on ground

136
Q

Controls need relatively high what?

A

pressure drops

137
Q

Pumps need what which should include all the necessary by-passes/on-off valves and check valves?

A

parallel spares

138
Q

In heat exchangers leaks can are preferred from which tube?

A

tube side to shell side

139
Q

Why would heat exchangers need a spare?

A

to be cleaned due to fouling during plant operation, all on-off valves need to be included for the spare

140
Q

What is the purpose of a hazard and operability study?

A

1 identifies hazards systematically (based on malfunctions)
2 does not address risk (probability can be high or very low)
3 addresses consequences (harmless or harmful)
4 proposes actions (design and/or operational)

141
Q

How many equipment are analyzed at a time?

A

1

142
Q

How do HAZOP describe the consequences of malfunctions and propose actions?

A

by identifying deviations and their cause

143
Q

Hazops are based on using what applied to parameters?

A

guide words

144
Q

Give examples of Guide Words.

A 
no or not
more
less
as well as
part of
reverse
other than/instead
early
late
before
after
145
Q

Give examples of parameters.

A 
Flow
Pressure
Temperature
Level
Time
Agitation
Reaction
Start-Up / Shut-Down
Draining / Venting
Inertising
Utility Failure
DCS fairue
Maintenance
Vibrations
146
Q

If a parameter does not apply you should do what?

A

check off and say does not apply if it doesn’t

147
Q

What should be focused on first during a HAZOP study?

A

cause

148
Q

How fast does sound travel?

A

343 m/s

Process Design and Safety (6 decks)

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