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CET I > Paper 2 > Flashcards

Paper 2 Flashcards

1
Q

Things that can go wrong with a catalyst

A

degradation e.g. sintering which reduces surface area, sulfur poisoning Pd by attaching to active sites, coking blocking access to surface of catalyst, thermal degradation, lifetime too short, someone else has the IP, may need high pressure leading to reactor failure

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2
Q

WFLITTENC

A

Waste, Financials, Location, Ingredients, Timescale, Toxics, Employment, Novelty, Catalyst

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3
Q

cash flow

A

net amount coming into a company in a set period of time. =income-expenditure

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4
Q

profit

A

sales revenue - total costs
gross profit is income minus expenditure, i.e. cash flow
taxable profit is profit minus allowance
net profit is gross profit minus tax

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5
Q

working capital

A

money needed to start up and run the plant before any sales generated. some recovered at end of project

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6
Q

can land be written off against tax?

A

no

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7
Q

book value of an asset

A

the depreciated value of the asset = historic cost minus accumulated depreciation

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8
Q

straight line depreciation

A

spreads the cost of the asset evenly through its useful life

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9
Q

declining balance or fixed annual percentage

A

e.g. annual depreciation charge=0.25*book value for each year.

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10
Q

which depreciation method should you use?

A

straight line for IP and buildings

UK prefers declining balance methods

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11
Q

are taxes rounded up or down?

A

down

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12
Q

“scrap value at the end of 6 years”

A

put the scrap in the year 5 row

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13
Q

limitations of RORI

A

only valid for an average year so doesn’t allow for changes in profits
does not consider time value of money

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14
Q

incremental RORI

A

further benefit over further cost

i.e. extra saving generated by the extra investment

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15
Q

interest

A

benefit gained without taking any risk

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16
Q

npv index

A

npv over capital required

for a project to be viable, want high NPV (>0) and high i* st the discount rate i is less than i* for the project

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17
Q

FAR

A

Number of deaths per 10^8 exposed hours (corresponding to a workforce of 1000 working for 50 years at 50 weeks per year and 40 hours per week)

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18
Q

how do chem eng’s write the second law of thermodynamics

A

dS=dq/T + dSgen where the dq is the same as dq appearing in the first law
dU=dq+dws-pdV

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19
Q

COP refrigeration cycle

do you want big or small COP?

A

COP refrig = heat in/net work in = ‘HINWI’

want small COP

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20
Q

what does presence of Re suggest

A

fluid flow, inertial and viscous forces present

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21
Q

what does Fr suggest

A

ratio of KE/PE where energy interchange btw these two forms is involved. suggests fluid flow subject to gravity/buoyancy

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22
Q

does temp change when you pass through a valve?

A

if ideal gas then no because isenthalpic, if real gas then temp changes even if isenthalpic

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23
Q

When was the Health and Safety at Work Act passed?

A

1974

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24
Q

concept of reasonably practicable

A

weighing a risk against the trouble, time and money needed to control it
decision weighted in favour of h & s
to avoid making sacrifice, duty-holder must demonstrate that the sacrifice is grossly disproportionate to the benefits of risk reduction that would be achieved

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25
Q

is reasonably practicable good?

A

can set goals for duty-holder without being prescriptive
subjective
can’t always rely on ‘good practice’ so can also use cost benefit analysis

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26
Q

what words does DiW love?

A

expertise, access, pipeline, utilities, licensed, plant capacity, supply chain, existing, meteorological, legislation
pros, cons and missing info

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27
Q

emplaces

A

expertise, meteorological, pipeline, legislation/license, access, capacity, existing, supply chain
also utilities

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28
Q

otto cycle is for petrol or diesel?
efficiency
limit on r

A

petrol
1-r^(1-gamma)
limit is r=10 with corresponding efficiency of 33%

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29
Q

Flixborough stats

A

1974

28 dead, 36 injured

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30
Q

piper alpha

A

1988

160+ dead

31
Q

Chernobyl effect on emergency services

A

1986
30 firemen dead
birth defects
135,000 evacuated

32
Q

bhopal

A

1984
4000 dead immediately
many blinded

33
Q

Seveso short term health disorders

A

1976
2000+ skin complaints
10 square miles of contaminated land

34
Q

example of panic buying

A

Buncefield 2005 - petrol

35
Q

what does leakage imply?

A

that a normal stress will be zero. e.g. for caps fastened on the end of a cylinder, sigma L =0 at the leakage point because the caps are clear of the cylinder

36
Q

what does the thin wall approximation lead to regarding the stress tensor?

A

tau xz=zx=yz=zy=0

note that tau zz is not necessarily zero

37
Q

when can you say that molar GA= molar GB?

A

at equilibrium btw a phase A and B of a PURE substance

38
Q

assumptions for Claudius Clapeyron

A

equilibrium between a phase A and B of a PURE substance, one phase is vapour, vapour is ideal gas

39
Q

permit to work system

A

controls implementation of potentially hazardous tasks
clear identification of who may authorise particular jobs
instruction in the issue, use and closure of permits
auditing to ensure sys works as intended
clear and standardised identification of tasks, risk assessments, permitted task duration
signature by designated authority
Piper alpha - new shift crew didn’t realise a maintenance task incomplete

40
Q

duty of care

A

employer assumes duty of care as part of voluntary contract with employee
provide safe premises, sys of work, materials & equipment, machinery, competent personnel
else law of negligence

41
Q

for which years do you calculate qualifying value and capital allowances?

A

the OPERATING years of the project

42
Q

is there an allowance on working capital?

A

no. you recover it the same year that you recover the scrap

43
Q

turbine isentropic efficiency

A

actual work out/ideal work out

44
Q

when can you say that Ws. = V. /\P ?

A

for an incompressible liq flowing through an isentropic pump

45
Q

partial molar property

A

change in total theta when one mol of species i added to very large amount of mixture

46
Q

sequence of steps for doing the partial molar property proof

A

differentiate property of the mixture wrt x1, notice that gibbs-duhem can be cancelled out, rearrange for partial molar theta, sub back into property of the mixture

47
Q

quotation for inherent safety

A

what you don’t have can’t leak

48
Q

what went wrong in Bhopal?

A

used a toxic intermediate methyl isocyanate. Water leaked into tanks leading to explosion and 42 tonnes of MIC released

49
Q

examples of protective devices for engineered safety

A

pressure safety release valves (last resort), non-return valves, high/low temp/pressure alarms, flameproof electrical equipment, process interlocks, fire detection and fighting systems

50
Q

are aqueous or oil based hydraulic fluids safer?

A

aqueous

51
Q

Law of strict liability

A

possessor of hazardous substance is prima facie responsible for damage caused by its escape
item 7 of HASAWA 1974: take reasonable care of all, comply with duties - makes negligence a criminal offence

52
Q

cost index formula

A

current cost = cost in year 1 * current cost index/cost index, year 1
i.e. cost/cost index is a constant for each year

53
Q

what might be the reason for a high ratio of one component of a feedstream to another?

A

maximising selectivity

54
Q

critical point

A

point of inflexion on P-V graph.
can’t have liq at temp above critical temp
thermodynamic properties of liq and vap identical
crit temps low for small molecs
when T less than Tc both liq and vap states can exist - which is more stable depends on pressure

55
Q

when wouldn’t you have a discontinuity in V-T graph?

A

when plotting at the critical pressure, there will be no step change in the graph.

56
Q

What is the dSgen term at equilbrium?

A

dSgen=0

57
Q

fine vs bulk

A

more expensive, lower volume, greater variety, greater complexity, greater added value, fewer application, various multi step syntheses possible, rarely need catalyst, greater raw material consumption, energy consumption, by-products, toxic compounds (e.g. phosgene, HCN), usually batch, greater investment/kg, greater labour, greater market fluctuations, fewer producers

58
Q

Raoult’s law

A

yiP=xiPisat

59
Q

under what conditions is a turbine adiabatic?

A

ideal gas, no friction in turbine, gamma indep of T

60
Q

for equilibrium of two phases in direct contact need

A

P, T and mu the same
also dmuA=dmuB
dGA=dGB

61
Q

definition of NPV

A

cumulative sum of DCF’s from year 0 to end of project
value today of the surplus a project is predicted to make over its lifetime over what it would make in a bank by investing at the company’s chosen rate i.

62
Q

when does Raoult hold

A

liq ideal mixt @ VLE

i.e. 1-1, 1-2 interactions identical

63
Q

what is ideal mixt

A

delta mix H and V are zero for IM
interactions equivalent
dG=VdP-SdT

64
Q

yield

A

mols of rctnt converted to specified product/mols of rctnt in feed

65
Q

selectivity

A

mols of rctnt converted to specified product/mols of rctnt consumed

66
Q

recycle ratio

A

recycle flowrate/fresh feed flowrate

67
Q

reduced temp

A

Tr=T/Tc

68
Q

when does Gibbs phase rule apply?

A

at eq, no chem rxn

69
Q

princ of corr states

A

all fluids similar at same Tr and Pr

70
Q

isolated sys

A

no energy no matter

71
Q

closed sys

A

energy but no material

72
Q

cts sys at SS

A

dU/dt =0

dV/dt =0

73
Q

when does the SFEE apply

A

open sys at SS i.e. dU/dt=0 and dV/dt=0

CET I (5 decks)

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