W1- Chemistry

Question 1

Petroleum

Answer 1

Mixture of HC w/ small amounts of organic (S,O,N) and oranometallics in sedimentary rocks

Question 2

Petroleum reservoir

Answer 2

Underground reservoir with HCs & its contents are reservoir fluid

Question 3

Paraffin

Answer 3

saturated HC (alkanes)

Decrease with higher MW

Question 4

Naphthenes

Answer 4

Saturated HC w/ 1+ rings (Cycloalkanes)

Question 5

Aromatics

Answer 5

HC with aromatic nuclei

Question 6

Olefins

Answer 6

Non-cyclic unsaturated HCs (ethynes, dienes)

Question 7

Suspended inorganic salts

Answer 7

i.e. NaCl -> HCl -> corrosion

Harm refinery operations:

Question 8

Heavy Metals & how removed

Answer 8

Ni, V, Fe, Cu

Deposition cause catalyst poisoning (FCC) and pipe/tank corrosion.

Removed by precipitation with HC solvents, distillation

Question 9

Sulfur

Answer 9

Sweet (<0.5 wt%); Sour (>1 wt%)

Cause corrosion of engines in gasoline/diesel

Question 10

Gas-to-oil-ratio (GOR)

Answer 10

Amount of gas produced in standard cubic feet (scf) to liquid oul prodcued at SC in stack tank barrel (stb)

Higher GOR = higher fuel quality

Question 11

API gravity

Answer 11

API = (141.5/SG) - 131.5

API < 10 Extra heavy oil
API <20-22 Heavy Oil
22<API<31 Medium Oil
API>31 Light oil

Question 12

Watson/UOP Characterisation factor

Answer 12

Differentiate between paraffinic and aromatics

Kw = (Tb^(1/3))/SG
Where Tb = normal BP (‘ R); ‘R = ‘F + 459.67

Increasing Kw: Aromatic < Naphthenic < Paraffinic

Question 13

Aniline point

Answer 13

Min. temp at which equal volumes of liquid HC and aniline (aromatic amine) are miscible

Aromatics have low aniline points

Question 14

Reid Vapour Pressure (RVP)

Answer 14

Absolute pressure exerted by a fuel mixture at 100’F and vapour-to-liquid volume ratio of 4

RVP indicates the volatility of liquid HC- can see if there is similar RVP to prevent explosions

Question 15

Cloud Point

Answer 15

Highest temp at which wax crystals begin to form and observed during gradual oil cooling under standard conditions

Low cloud point products desirable in low temp conditions

Wax crystals plug fuel system lines/stalling aircraft

Question 16

Pour point

Answer 16

Lowest temp at which oil pours/flows when cooled without stirring under standard conditions

Lowest temp that oil can be stored and capable of flowing under gravity (T&S requirement)

Question 17

Flash point

Answer 17

Min temp which its vapour pressure is sufficient to produce vapour for spontaneous ignition of HC with air with presence of external source

Critical for safety for volatile product T&S- temp around storage tank below flash to prevent ignition

Question 18

Fire point

Answer 18

Min temp at which the HC will continue to burn for at least 5s after ignition by flame

Question 19

Autoignition point

Answer 19

Min temp which HC vapour mixed with air can spontaneously ignite without any spark

Crucial for process safety studies & compressed HCs

Question 20

Smoke Point (SP)

Answer 20

Maxx flame height which fuel can be burned in standard wick-fed lamp without smoking

High SP implies low smoke producing tendency

High aromatics = low SP (smoky flame)

Question 21

Carbon Residue (CR)

Answer 21

Formed from vaporising non-volatile compounds in crude in absence of air (1 atm)

Heavier fractions = more aromatics = less volatiles = Higher CR
(Light oils of gasoline/naphtha has CR=0)

Question 22

Octane Number (ON)

Answer 22

Quantifies antiknock characteristics of fuel burning in spark-ignition engine (ability to resist auto-ignition during compression and prior to knock/ignition)

Higher ON means better engine performance
Isoparaffins and aromatics have high ON, while n-paraffins and olefins have low ON

Question 23

Motor Octane Number (MON)

Answer 23

High speed performance measured under heavy road conditions

Question 24

Research Octane Number (RON)

Answer 24

Road performance under lower speed driving conditions

Question 25

Post octane number (PON)

Answer 25

Average of MON+RON

Question 26

Cetane number (CN)

Answer 26

Quantifies ignition delay

Shorter ignition delay = higher CN (auto-ignition desired)

Higher CN fuels reduce combustion noise, improve combustion control, higher engine efficiency, easier engine starting

Organic additives to improve CN

CN = vol%n-cetane + 0.15(vol% HMN)