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Liquid Cargoes > Chemistry of Oil > Flashcards

Chemistry of Oil Flashcards

1
Q

what is crude oil?

A

raw material (decomposed vegetation + animal life compressed - high pressure, millions of years)

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2
Q

examples of products from crude oil:

A

motor + activation; - gassoline - kerosene - diesel - gass oil - fuel oil (all refined)

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3
Q

what is crude oil made up from?

A

hydrogen + carbon (+ range of components e.g. sulphur to water)

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4
Q

what is the generic name for any petroleum (crude + by-products)?

A

hydrocarbons

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5
Q

what is the simplest form of a hydrocarbon molecule?

A

methane (gas) - CH4

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6
Q

what determines the physical characteristics of the petroleum?

A
  • length of chain - manner in which they are joined
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7
Q

what is the second smallest petroleum hydrocarbon?

A

ethane (C2H6)

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8
Q

what state are hydrocarbons in if they have less than 5 carbon atoms at normal ambient temp + pressure?

A

gases

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9
Q

what state are hydrocarbons in if they have between 6 and 19 carbon atoms at normal ambient temp + pressure?

A

liquids

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10
Q

what state are hydrocarbons in if they have 20 or more carbon atoms at normal ambient temp + pressure?

A

solids

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11
Q

what is an octane rating?

A

a measure of flammability

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12
Q

what are aromatics?

A

ring-type arrangements of hydrocarbons

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13
Q

why are aromatics more reactive?

A

they are hydrogen deficient

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14
Q

what process do all different ways of refining crude oil start with?

A

the distillation process (fractionating)

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15
Q

what process comes after distillation in refining crude oil?

A

cracking

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16
Q

how and why can different components of crude oil be distilled (into fractions)?

A
  • heating - different boiling points
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17
Q

what is the diagram associated with atmospheric distillation of crude oil

A
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18
Q

what is the main difference between atmospheric distillation and vacuum distillation?

A

vacuum distillation can be done at higher temperatures

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19
Q

what are the main hazards of petroleum?

A
  1. flammability
  2. toxicity
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20
Q

what 2 things have to be considered when discissing flammability?

A
  1. vapour pressure
  2. volatility
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21
Q

what are the main considereations of crude oil based cargo in relation to vapour pressure?

A
  • water evapourates slowly - gasoline evapourates quickly
  • petroleum = various components of hydrocarbon family- some more volitile than others
  • some exist as gases - may have evapourated off before reaching ship
  • within cargo tank - oil = different from chemical make up of vapour in ullage space above cargo
  • in vapour = more lighter components - evapourate 1st
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22
Q

what temperature is absolute zero?

A

-273 *C

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23
Q

how are molecules bound together?

A

inter-molecular attraction

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24
Q

what is evapouration?

A

changing from liquid to a vapour

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25
Q

what is condensation?

A

changing from vapour to liquid

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26
Q

what does S.V.P stand for?

A

saturated vapour pressure

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27
Q

when does S.V.P (saturated vapour pressure) stop?

A

when there are an equal number of molecules leaving the liquid as there are re-entering it

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28
Q

what does S.V.P mean?

A

no more vapour can be produced at that temperature

29
Q

what happens to the S.V.P reading if the temperature is increased?

A

S.V.P reading increases with temperature

30
Q

what does T.V.P stand for?

A

true vapour pressure

31
Q

what does R.V.P stand for?

A

Reid Vapour Pressure

32
Q

what is the T.V.P?

A

the highest vapour pressure possible

33
Q

when does the T.V.P occur?

A

when the gas to liquid ratio is effectively zero

34
Q

what makes the T.V.P difficult to measure?

A

you need to have detailed knowledge of the molecular makeup of the liquid in question

35
Q

where can you find the R.V.P test results on a ship?

A

on load port documentation

36
Q

what is the diagram of the R.V.P testing equipment?

A
37
Q

what does the amount of evapouration depend on for any given liquid?

A
  • surface area
  • vapour to liquid ratio
  • turbulence
38
Q

why does the surface area rather than the volume of a liquid effect the evapouration rate?

A

evapouration occurs only at the surface of a liquid (not in the body)

39
Q

what is the ullage space?

A

space above the liquid in a cargo tank

40
Q

why is the density of a vapour a concern on a ship?

A
  • most hydrocarbon are denser than air
  • tend to linger at bottom of tanks, pumprooms etc.
  • causing problems in removing the vapour
41
Q

why is flammability a concern in relation to vapour of a liquid?

A
  • liquids cannot burn unless vapour is produced
  • flammability is a function of the ability to give off vapour
42
Q

what is the Flashpoint?

A

the lowest temperature at which a liquid gives off enough vapour to form a flammable mixture in air when an external ignition source is applied

43
Q

what 3 things need to be present at the same time for fire to occur?

A
  1. fuel
  2. oxygen
  3. source of ignition (generates heat)
44
Q

what is the Flammable Range?

A

the region between the Lower and Upper Flammable Limits

45
Q

what happens to the Flammable Range if the oxygen content is reduced?

A

Flammable Range decreases until at about 11% oxygen by volume - insufficient air to sustain combustion

46
Q

how is the atmosphere described if the space above the Upper Flammable Limits (U.F.L)?

A

Too Rich

47
Q

how is the atmosphere described if it is below the Lower Flammable Limits (L.F.L)?

A

Too Lean

48
Q

Where should all safe tanker opperations aim to opperate in relation to the Flammable Zone?

A

Aim to opperate outside of the Flammable Zone at all times!

49
Q

What is the main source of reference for tanker safety?

A

the Internation Safety Guide for Oil Tankers and Terminals

50
Q

how does the International Safety Guide for Oil Tankers and Terminals classify petroleiums’?

A

into 2 groups:

  1. Volatile
  2. Non-Volatile
51
Q

What is threshold for classifying petroleums as volatile or non-volatile?

A
  • those with a flashpoint below 60*C = volatile
  • flashpoint of 60*C or above = no-volatile
52
Q

what significance has temperature of 60*C in relation to volatility of petroleums’?

A

an arbitary temperature of classification of petroleum - above ambient temperatures found anywhere in the world

53
Q

why is liquid being sprayed out of a small hole in a pipe particularly dangerous in relation to the flashpoint of that liquid?

A

the flashpoint falls - specific surface area involved

54
Q

what is the Fire Point of a substance?

A

Temperature at which the substance gives off enough vapour to ignite + stay alight (when exposed to external source of ignition)

55
Q

what is the Auto Ignition Temperature?

A

if a flammable liquid is heated sufficiently high - vapour will ignite without external source of ignition being applied

56
Q

what does A.I.T stand for?

A

Auto Ignition Temperature

57
Q

What does Toxic mean?

A

Poison

58
Q

what are the main routes of entry into the body for a toxic substance?

A
  • ingestion
  • inhalation
  • intra dermal (through the skin)
59
Q

Name 2 examples of acute poisons:

A
  1. cyanide
  2. hydrogen sulphide
60
Q

name 3 chronic poisons:

A
  1. lead
  2. mercury
  3. benzene
61
Q

what are Time Weighted Averages?

A

Standards established for concentrations of airbourne substances based on what humans can tolerate safely with no ill effects for an 8 hour working day, every day

62
Q

what does O.E.L stand for?

A

Occupational Exposure Limit

63
Q

What are the 2 types of O.E.L?

A
  1. Long term - 8 hour T.W.A
  2. Short term - 15 minute one off exposure at a higher level
64
Q

what does O.E.L mean?

A

set level that, based on current scientific knowledge - won’t damage a worker through inhalation day after day

65
Q

what does M.E.L stand for?

A

Maximum Exposure Limit

66
Q

what does P.E.L stand for?

A

Permissible Exposure Limit

67
Q

why were M.E.L and P.E.L limits introduced?

A

for substances that cause most harm to health - ‘safe’ levels of exposure cannot be ascertained or are unachievable

68
Q
A

Liquid Cargoes (11 decks)

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