Plantkennis

Question 1

Wat is het doel van de RAF met het overtollige gas?

Answer 1

De raffinaderij produceert meer fuelgas dan voor eigen gebruik nodig is. Het overschot dient dus op de markt te worden afgezet. De diverse raffinaderij processen leveren fuelgas van verschillende kwaliteit, afhankelijk van de samenstelling en derhalve met een verschillende marktwaarde. Het is de bedoeling fuelgas met een hoge marktwaarde te verkopen, terwijl minder waardevol gas als brandstof in de raffinaderij wordt gebruikt.

Question 2

Welke 3 soorten fuel gas worden geproduceerd?

Answer 2

o Low Joule Gas (LJG); dit is gas met een lage verbrandingswaarde. o Saturated High Joule Gas (SHJG); dit is gas met een hoge verbrandingswaarde bestaande uit verzadigde verbindingen o en Unsaturated High Joule Gas (UHJG); dit is gas met een hoge verbrandingswaarde bestaande uit onverzadigde verbindingen.

Question 3

Waar wordt LJG geproduceerd? Waarom is een speciaal fornuis nodig?

Answer 3

LJG wordt in de Flexicoker Gasifier geproduceerd; het heeft een lage verbrandingswaarde en een lage druk. De totale hoeveelheid geproduceerde LJG moet in de raffinaderij worden gebruikt, omdat het niet geschikt is om verkocht te worden en wel om de navolgende reden: o Vanwege de lage verbrandingswaarde en het grote volume is een speciaal fornuis ontwerp nodig.

Question 4

Wat is SHJG? Waarom is SHJG niet geschikt voor verkoop?

Answer 4

Verschillende units van de raffinaderij en ExxonChemicals produceren SHJG, een gas met een hoge verbrandingswaarde. Dit gas bestaat uit verzadigde verbindingen, maar de samenstelling kan sterk uiteen lopen. Omdat produkten, die bedoeld zijn voor verkoop aan bepaalde specificaties moeten voldoen, is SHJG met zijn wisselende samenstelling minder voor verkoop geschikt.

Question 5

Wat is UHJG? Waar wordt dit gemaakt? Wat moet worden gedaan om het gas verkoopbaar te maken?

Answer 5

In de Flexicoker Light Ends Unit wordt een gas met veel onverzadigde verbindingen en een hoge verbrandingswaarde geproduceerd. De samenstelling van dit UHJG is tamelijk constant, zodat het vrij gemakkelijk aan de meeste specificaties kan voldoen. Toch is het nodig het UHJG te comprimeren en het dauwpunt en het sulfur content (het zwavelgehalte) te verlagen, alvorens het gas naar de afnemer te sturen. Deze behandelingen ondergaan het UHJG in de SalesGas Treating Unit.

Question 6

Wat kan als back-up fuel worden gebruikt? Wat zorgt ervoor welke fuel wordt gebruikt?

Answer 6

o High Joule Natural Gas (HJNG), dit is aardgas met een hoge verbrandings waarde, dat van de Gasunie wordt gekocht. o Vaporized LPG. o nC4 ex T 181. o C3, mix C4 en nC4 ex tankage. Of HJNG of LPG als back-up gebruikt wordt is van een aantal factoren afhankelijk zoals beschikbaarheid en prijs. Zo geldt er voor HJNG vaak een contractueel bepaalde hoeveelheid die ingenomen mag worden met hoge boetes bij een overschreiding van deze contracthoeveelheid.

Question 7

Waaruit bestaat RHJG?

Answer 7

SHJG en de overige gassen te weten UHJG, HJNG en vaporized LPG (indien nodig), worden met elkaar vermengd tot Refinery High Joule Gas (RHJG). Voor LJG met zijn lage druk en lage verbrandingswaarde wordt een apart distributienet gebruikt.

Question 8

Uit welke twee delen bestaat het refinery fuelgas system? Welk ander system bestaat er naast deze twee?

Answer 8

o De opvang en distributie van het RHJG. o De distributie van LJG. Naast dit fuelgas systeem bestaat er nog een HJNG systeem, dat pilot gas levert aan alle fornuizen en boilers. Dit systeem levert ook het HJNG, dat als back-up fuel voor het RHJG wordt gebruikt en verder HJNG voor diverse andere fuel behoeften in de raffinaderij.

Question 9

Hoe wordt RHJG gemaakt? Uit welke componenten bestaat dit?

Answer 9

Het hoofdbestanddeel van het RHJG, het SHJG , wordt bij de verschillende processen opgevangen en naar een centrale verzameldrum (collection drum) gevoerd (D997).Hier worden ook de overige componenten bijgeblend. o UHJG van de Flexicoker Light Ends unit o HJNG van het HJNG distributiesysteem o Vaporized LPG van de LPG-vaporizers. De vaporizer feed heeft drie bronnen, namelijk - process rundown (nC4 ex T 181) - offsite tankage (C3, mix C4 en nC4) - off-spec rundown

Question 10

Waar wordt LHJ gemaakt? En waar naartoe getransporteerd?

Answer 10

LJG wordt in de Flexicoker Gasifier Unit gevormd en wordt naar de fornuizen en de boilers, aangegeven in figuur 020.1, getransporteerd. Aangezien LJG verkocht noch opgeslagen kan worden, moet LJG met dezelfde hoeveelheid worden verbruikt waarmee het wordt geproduceerd. De regelingen, die hiervoor zorgen, maken deel uit van de Flexicoker Heater overhead en van het SG-8101 boiler systeem.

Question 11

Geef een overzicht van de afnemers van LJG

Answer 11

Question 12

Geef een schematisch overzicht van het HJNG netwerk

Answer 12

Question 13

Geef een schematisch overzicht van het RHJG netwerk

Answer 13

Question 14

Welke 4 basis processen zijn er om crude oil in finished product te raffineren?

Answer 14

–Separation

–Conversion

–Treating

–Blending

Question 15

Geef de definitie van destillatie

Answer 15

• A process in which heat is used to separate a mixture of liquid materials into two or more relatively pure products
• Occurs because of the difference between the boiling points of materials

–The lighter components vaporize while heavier components condense at the same temperatures

Question 16

Geef de definitie van flashing

Answer 16

• The sudden vaporization of a light fraction in a heavier stream induced by an instantaneous pressure drop
• Occurs when a stream under pressure is introduced into a vessel

–The lighter components vaporize out of the liquid stream easier as the pressure is reduced

Question 17

Geef de definitie van stripping

Answer 17

• The separation of a contaminant from a feed mixture by injection of steam or other light components
• Occurs when vapor is injected into the tower

–Reduces the partial pressure of the components in the tower

–The lighter components vaporize easier as the partial pressure of each component of the feed mixture is reduced

Question 18

Geef de defintie van absorptie

Answer 18

• The selective combination of a component and the material to be extracted
• Occurs when a similar material (sponge oil) is injected at the top of a tower

–Sponge oil condenses and absorbs the desired lighter component as it flows down the tower

–The sponge oil and product are sometimes separated by distillation or steam stripping and the sponge oil reused

Question 19

Geef de defintie van extractie

Answer 19

•Similar to Absorption

–A liquid solvent is used to dissolve and remove the extract rather than a similar hydrocarbon component

•Occurs when a solvent is mixed with a feedstock

–The solvent dissolves the component to be separated

–The solvent and product are sometimes separated by distillation or steam stripping and the solvent reused

Question 20

Geef de defintie van settling

Answer 20

• The separation of one component of a mixture from another component of the mixture by density difference
• Occurs when a mixture is introduced to a large vessel

–The vessel provides sufficient residence time for the more dense material to drop out

Question 21

Geef de defintie van crystallizatie

Answer 21

•A chemical solid-liquid separation technique in which transfer of a solute from the liquid solution to solid crystalline phase occurs

–Liquid solution is chilled or a solvent is added

–Solid crystals precipitate from the solution

–Crystals grow to reach a critical size, reach equilibrium and become stable

–Solution is passed through a filtering mechanism which “catches” the crystalline structures

–Crystals are mechanically removed and liquefied by dissolution or melting

Question 22

Geef de defintie van filtratie

Answer 22

•The mechanical or physical process of separating solids from fluids by interposing a medium through which the fluid can pass, but the solids are retained

–Used for the purification of fluids (either liquid or gas)

–Uses a multilayer medium where particles unable to follow the channels of the filter will adhere to the structure of the medium and be retained

•May use a chemical agent as a catalyst to assist the separation

–Catalysts are use to promote a chemical reaction

–Uses a reagent to precipitate one material and then a filter to separate the solid from the solution

–Uses a solvent to dissolve one material into solution and then a filter to separate the dissolved component from the remaining material

Question 23

Wat wordt met conversie bedoeld?

Answer 23

•Conversion

–Changes the size and/or structure of hydrocarbon molecules

–Usually involves a chemical reaction and catalysts to promote the chemical reaction to take place

ØCatalysts are substances that increase the rate of chemical reactions and are not consumed by the reaction

ØDepending on formulation catalysts promote certain reactions over others and give selectivity to desired products

–Performed using any of three main processes

ØDecomposition

ØUnification

ØAlteration

Question 24

Welke drie processen van conversie zijn er?

Answer 24

ØDecomposition

ØUnification

ØAlteration

Question 25

Wat is decompositie?

Answer 25

•Dividing large heavy hydrocarbon molecules into smaller lighter molecules

–Improves the proportion of high valued products

–Comparable to cutting a link on a chain to make two smaller chains

•Accomplished by thermal or catalytic cracking of the larger molecules

–Thermal cracking uses time and temperature to crack large molecules into smaller molecules without the selectivity that catalyst offers

–Catalytic cracking uses catalyst based process to crack large molecules into smaller molecules

ØCatalyst is used to increase yield and conversion selectivity to the desired products

Question 26

Wat wordt onder thermal cracking verstaan?

Answer 26

•Uses hydrogen in a reactor at moderate temperatures and high pressures to crack middle and heavy feed molecules into lighter, more valuable products

Question 27

Geef een voorbeeld van thermal cracking

Answer 27

•Uses time and temperature to crack large fuel oil molecules into smaller transportation fuel molecules without the selectivity catalyst offers

Question 28

Vertel iets over steam cracking

Answer 28

•Uses hydrocarbon diluted with steam in high temperature cracking furnaces to crack into ethylene, propylene, butadiene and hydrogen

–Product composition and quantity depend on feed composition, steam ratio, cracking temperature and furnace residence time

Question 29

Vertel iets over catalytic cracking

Answer 29

•Uses high heat and a fluidized catalyst bed reactor to crack heavier fuel oil molecules to lighter higher value fuel products

Question 30

Vertel iets over decompositie, S recovery proces

Answer 30

• Know as the Claus Process
• Uses a two step process to convert hydrogen sulfide and sulfur dioxide to elemental sulfur and water

–Step one – a high temperature thermal step where hydrogen sulfide is oxidized in a reaction furnace to produce some sulfur and sulfur dioxide

–Step two – a lower temperature catalytic step where the remaining hydrogen sulfide and sulfur dioxide are reacted in activated alumina catalyst beds to make more sulfur

Question 31

Vertel iets over unification

Answer 31

•Combining small light hydrocarbon molecules into larger heavier molecules

–Improves the proportion of higher valued products

–Comparable to adding a link to two short chains to make a longer chain

•Accomplished by catalytic combination of the smaller molecules

–Catalytic combination uses a liquid or solid catalyst to promote the reaction

Question 32

Vertel iets over polymerizatie

Answer 32

•The Unipol process (originally developed by Union Carbide Corp) turns ethylene gas (C2=) into low density polyethylene which is widely used in film packaging applications.

–The unification reaction is carried out in a gas phase fluidized bed

– Polymerization reactions generate heat, i.e., they are exothermic

Question 33

Geef drie voorbeelden van unification en leg uit

Answer 33

•Grease Compounding

–Combines two or more substances with distinct compositions in a chemical reaction to form a product with its own distinct characteristics

ØCompound products cannot be separated into original elements by physical or mechanical means

•MTBE

–Combines isobutylene and methanol with a strong acid ion exchange catalyst to produce a mixture of MTBE for gasoline oxygenation

•Alkylation

–Combines propylene, butylene and isobutane with a strong acid catalyst (sulfuric or hydrofluoric acid) at mild temperatures to produce high octane gasoline blending components

Question 34

Wat is alteration?

Answer 34

•Re-arranges the structure of straight chain molecules to create short branch chain Isoparaffins and ring chain aromatics

–Improves the proportion of higher valued products

ØStraight chain paraffins having a relatively low octane number are changed to branch chain isomers and ring chain aromatics that have high octane numbers

•Accomplished by using high heat, hydrogen and Catalytic reactions

Question 35

Geef twee voorbeelden van alterations

Answer 35

•Catalytic Reforming

–A series of catalytic reactions using high heat and hydrogen to convert naphtha to more complex molecular shapes

ØReactions produce hydrogen

•Isomerization

–Changes the structure of molecules converting normal paraffin straight chain molecules to Isoparaffin branched molecules

ØBranched molecules have higher octane numbers or lower pour points

Question 36

Welke drie hoofdprocessen zijn treating?

Answer 36

–Dissolving

–Absorption

–Precipitation

Question 37

Wat is treaten?

Answer 37

• Removing undesirable molecules to improve product quality
• Include chemical or physical separation

Question 38

Wat is dissolving?

Answer 38

•One substance forms a homogeneous mixture with another substance

–The resulting mixture is called a solution

–The substance dissolved (Solute) and the substance initiating the dissolving (Solvent) may be a gas, a liquid or a solid

ØAs long as the Solute continues to be dissolved in the Solvent the solution is unsaturated

ØIf the Solvent can dissolve no more Solute the solution is saturated

+Warmer temperatures allow a solution to hold more solute before it becomes saturated

Question 39

Wat is absorptie?

Answer 39

•A vapor mixture is contacted with a solution selected to preferentially absorb one or more components from the mixture

–The purpose is either to recover a desired component from the mixture or remove an impurity from the mixture

ØUsing a gas to extract a component from a liquid is referred to as stripping

ØRemoving an impurity from a mixture is referred to as scrubbing

Question 40

Wat is precipitatie?

Answer 40

•Occurs when an insoluble substance is formed in a solution due to a chemical reaction or condensation

–A precipitate may be removed from solution by physical means

ØSettling

ØCentrifuging

ØFiltering

Question 41

Wat is desalting?

Answer 41

•The removal of salts, silt, sand and other suspended solids from crude oil

–Water is added to Crude oil to dissolve salts and put other solids in suspension

–The water and dissolved/suspended impurities are then removed in a vessel with an electric grid coalescer called a Desalter

•Impurities not removed could

–Foul exchangers and towers reducing unit capacities

–Promote increased corrosion rates

–Poison downstream unit catalysts

Question 42

Wat is drying?

Answer 42

•The removal of liquid (usually water) which could affect process reactions or product quality

–Water left in product streams will promote

ØCorrosion in units with acidic atmospheres

ØUpsets in units operating at extremely high or low temperatures

ØProduct contamination

ØPoor finished fuel operability

Question 43

Wat is sweetening?

Answer 43

•The chemical process of removing or converting sulfur compounds (mercaptans, H2S) from products to improve color, odor and oxidation stability

–Uses Merox catalyst to convert mercaptans to disulfides

–Uses caustic solution washes for H2S removal

Question 44

Wat is hydrotreating?

Answer 44

•Catalytic process used to remove contaminants from intermediate components and product streams

–Removes sulfur by conversion to hydrogen sulfide

–Contaminants such as nitrogen, sulfur and metals can poison downstream catalytic processes

•Uses elevated temperatures and pressures in the presence of hydrogen and a catalyst

–Saturation of olefins and conversion of aromatics produce cleaner burning compounds

Question 45

Wat is solvent extraction?

Answer 45

• Selectively dissolving one or more constituents of a solution in a suitable solvent to remove a contaminant
• Benefits include:

–Decreased corrosion

–Protection of downstream catalytic processes

–Improved finished product quality

•Used in lube oil production to remove aromatic hydrocarbons from the base stock

–Widely used extraction solvents are:

ØPhenol

ØFurfural

ØSulfolane

ØCresylic acid

Question 46

Wat is solvent dewaxing?

Answer 46

• Extraction process used to remove wax from base stocks
• Process steps include:

–Mixing feedstock with a solvent to dissolve the wax

–Precipitating the wax from the mixture by chilling

–Recovering the solvent for recycle through filtering or membrane technology

•Toluene and Methyl Ethyl Ketone (MEK) are common solvents for de-waxing, but many other solvents are used depending on desired results

Question 47

Wat is blending? Wat is de reden van blending?

Answer 47

•The Primary Blending Objective is to achieve the lowest cost mixture of available blending components that will meet product specifications

–The process of physically mixing two or more streams in the proper proportions to create a product that meets required specifications and will perform as expected

•Blending is necessary for most fuel products because:

–Most process unit rundown streams typically do not meet all of the finished fuel quality requirements

–We want to minimize product quality giveaway

–We want to optimize the components to create the lowest cost blend

Question 48

Wat is het karakteristieke van een component van een blend?

Answer 48

•The Primary Blending Objective is to achieve the lowest cost mixture of available blending components that will meet product specifications

–The process of physically mixing two or more streams in the proper proportions to create a product that meets required specifications and will perform as expected

•Blending is necessary for most fuel products because:

–Most process unit rundown streams typically do not meet all of the finished fuel quality requirements

–We want to minimize product quality giveaway

–We want to optimize the components to create the lowest cost blend

Question 49

Wat houdt blend management in?

Answer 49

•The Primary Blending Objective is to achieve the lowest cost mixture of available blending components that will meet product specifications

–The process of physically mixing two or more streams in the proper proportions to create a product that meets required specifications and will perform as expected

•Blending is necessary for most fuel products because:

–Most process unit rundown streams typically do not meet all of the finished fuel quality requirements

–We want to minimize product quality giveaway

–We want to optimize the components to create the lowest cost blend