Refinery Processes Industry Guide - PRO-QUIP

1 Refinery ProcessesIndustry GuideFlow Control DivisionValtek Control Products2 Flowserve Corporation, Flow Control Division, Valtek Control ProductsTable of ContentsIntroduction to Refining5 Crude Distilling Unit6 Crude Oil Charactertistics6 Introduction to Distillation7 Control Valve Guidelines9 Control Valve Applications9 Recommended Control Valves10 Alkylation11 Introduction to Alkylation11 Chemistry Overview11 Alkylation Process11 Hydrofluoric Acid Process12 Control Valve Guidelines (Hydrofluoric Acid Applications)12 Sulfuric Acid Alkylation Process12 Control Valve Guidelines (Sulfuric Acid Applications)13 Control Valve Applications14 Recommended Control Valves14 Catalytic Reformer15 Introduction to Catalytic Reforming15 Reformer Equipment15 Regeneration16 Control Valve Guidelines17 Control Valve Applications18 Recommended Control Valves18 Hydrotreating19 Introduction to Hydrotreating19 Sulfur Facilities20 Sulfur Recovery20 Combustion20 Reaction21 Control Valve Guidelines21 Control Valve Applications22 Recommended Control Valves22 Vacuum Flashing23 The Cracking Phenomenon23 Low Pressure24 Vacuum Flashing24 Control Valve Guidelines25 Control Valve Applications25 Recommended Control Valves25 Refinery Processes Industry Guide3 Flowserve Corporation, Flow Control Division, Valtek Control ProductsRefinery Processes Industry GuideTable of Contents (continued)

2 Isomerization Plant26 Introduction to Isomerization26 Butane Isomerization27C5/C6 Isomerization28 Control Valve Guidelines28 Control Valve Applications28 Recommended Control Valves28 Gas Plants29 Introduction to Gas Plants29 Saturates (Sats) Gas Plant29 Cracked Gas Plant30 Control Valve Guidelines30 Control Valve Applications31 Recommended Control Valves31 olefins Plant32 Ethylene Plants32 Refinery Interaction32 olefins Process33 olefins Plant Compression Train33 Control Valve Guidelines35 Control Valve Applications35 Recommended Control Valves35 Catalytic Cracking37 Introduction to Catalytic (Cat) Cracking37 Cat Cracker Process37 Reaction Section38 The Regenerator38 The Fractionator39 Process Variables40 Feed Quality40 Reactor Temperature40 Feed Rate and Recycle Rate40 Time of Day and Temperature40 Control Valve Applications41 Recommended Control Valves414 Flowserve Corporation, Flow Control Division, Valtek Control ProductsHydrocracking Plant42 Introduction to Hydrocracking42 Hydrocracking Process42 Control Valve Guidelines43 Control Valve Applications44 Recommended Control Valves44 Thermal Cracking Plant45 Introduction to Thermal Cracking45 Control Valve Guidelines46 Control Valve Applications47 Recommended Control Valves47 Coking Plant48 Introduction to Coking48 Coking Process48 Coke49 Control Valve Guidelines49 Control Valve Applications49 Recommended Control Valves49 Glossary51 Credits53 Table of Contents (continued)5 Flowserve Corporation, Flow Control Division, Valtek Control ProductsFigure 1.

3 Refining Process Flow DiagramIntroduction to RefiningThe modern crude oil Refinery is designed to convertbasic raw crude oil into various useful products througha series of separation and chemical Processes . Forexample, the Refinery process is used to produce gaso-line, kerosene, light oils, lubricating oils, and nature, many refining applications are severe ser-vices characterized by extreme temperatures, erosion,corrosion, and high pressure drops. With strict environ-mental requirements, process equipment must alsorestrict fugitive emissions to acceptable purpose of this Guide is to outline these Processes ,while offering selection guidelines for choosing the cor-rect control valve for a particular refining shown in Figure 1, a typical Refinery is divided intoseveral subprocesses or IndustryCrude DistillingUnitHydro-TreatersCatalyticRef ormerIsom-erizationPlantHydrotreater,Hyd ocracker Gas PlantGasoline BlendingCatalyticCrackerThermalCracker(o r Coker)

4 HydrocrackerAlkylationPlantGasPlantGasol ineBlendingOlefinsPlantVacuumFlasherGaso lineBlendingGasolineBlendingGasolineBlen dingAsphaltJet FuelDistilled FuelsDistillate FuelsGas PlantCatalyticReformerGas Plant Gasoline Blending Hydrocracker or Distillate Fuel Hydrocracker, Residual Fuel, AsphaltThermal Cracker,Residual FuelCrudeOilNaphthaKeroseneStraight-runL ight Gas OilStraight-runHeavy Gas OilButane, Propane, Fuel GasPentanes and HexanesStraight-run (or Long) ResidueFlasher TopsFlasher BottomsHydrogenLight GasesReformateLight GasesC5 & C6 Isomerate-Fuel GasPropaneNormal ButaneIso-butaneEthylenePropyleneMixed C4'sCracked GasolineCracked Gas OilCracked PitchAlkylatePropaneNormal ButaneLight GasesPropane/PropyleneButane/ButyleneCat -Cracked GasolineCat-Cracked Light Gas OilCat-Cracked Heavy Gas OilCracked GasesCracked GasolineCracked Light Gas OilCracked Heavy Gas Oil(Coke)HydrogenStraight-run Gas OilsCracked Gas OilsReformateCracked GasolineStraight-run GasolineIsomerateButanesand LighterGasolineGasolineDistillateHydrocr ackateJet Fuel,DistillateFuel6 Flowserve Corporation, Flow Control Division, Valtek Control ProductsCrude Oil CharacteristicsCrude oil is a carbon- and hydrogen-based natural re-source liquid used to produce petroleum products.

5 It isnot just one chemical compound; rather, it is a mixtureof chemical compounds. This becomes apparent whenthe crude oil is heated. When heated to its boiling point,crude oil does not completely evaporate and leaves aresidue. In contrast, if water (which is a pure compound)is heated to its boiling point and left at that tempera-ture, it would continue to boil until no water thermometer would indicate that the water stayed atits boiling point 212 F at psia (100 C at 1 bar)throughout the 2: Crude Distilling UnitCrude Distilling UnitUnlike water, crude is not a single chemical compound,but rather thousands of different chemical of these compounds are as simple as methane(CH4) or more complex such as isooctane (C8H18). Theimportant point to remember is that each one of thesecompounds has its own boiling temperature. For ex-ample, if a vessel filled with a medium weight crude isheated until it reaches a temperature of about 150 F(66 C), the oil will begin to boil.

6 If enough heat is ap-plied to keep the vessel at 150 F (66 C), soon thevessel will stop boiling. If the heat is applied to raisethe temperature to 350 F (177 C), the vessel will be-gin to boil again and stop after a period of Corporation, Flow Control Division, Valtek Control ProductsWhen further specifying the character of crude oil,grouping certain compounds in fractions or cuts is use-ful. The typical crude oil has the following fractions:Table I: Crude Oil Temperatures/FractionsTemperaturesFracti onLess than 90 F (32 C)butanes and lighter90 - 220 F (32 - 104 C)gasoline220 - 315 F (104 - 157 C)naphtha315 - 450 F (157 - 232 C)kerosene450 - 800 F (232 - 427 C)gas oil800 F ( 427 C) and aboveresidueCrude oil compositions may vary widely. Light crudeoil tends to have more gasoline, naphtha and kerosene;heavy crude oil tends to have more gas oil and resi-due. Generally, the heavier the compound, the higherthe boiling 5: Crude Entering theDistilling ColumnFigure 4: Crude Oil Feed to DistillingIntroduction to DistillationDistillation is the process of using heat to separate lightand heavy crude oil.

7 To begin the distillation process,the crude oil is heated to about 800 F (426 C) and flowsto the bottom of the main crude column (Figure 4).CRUDETANKCHARGEPUMPFURNACEDISTILLINGC OLUMNHEATEDCRUDEVAPORLIQUIDThis process can be repeated many times, boiling offmore crude with each step and increase in tempera-ture. The compounds that boil at a temperature below150 F (66 C), vaporized in the first step, while thecompounds that boil at a temperature between 150 Fand 350 F (66 and 177 C) vaporized in the secondstep, and so forth. With this process, a distillation curvecan be developed, which is a plot of temperature onone scale and the percent evaporated on the type of crude oil has a unique distillation curvethat determines what kinds of chemical compounds arein the crude (Figure 3).Figure 3: Crude Oil Distillation Curveand Fractions1000900800700600500400300200100 1002030405060708090100 BUTANES AND LIGHTERGASOLINENAPHTHAKEROSENEGAS-OILRES IDUECUMULATIVE PERCENT VOLUME BOILING TEMPERATURE F 8 Flowserve Corporation, Flow Control Division, Valtek Control ProductsFigure 6: Bubble Cap on a DistillingColumn TrayFigure 7: Downcomers and SidedrawsTRAYLIQUIDBUBBLECAPVAPORLIQUIDD OWN-COMERVAPORSLIQUIDSDOWN-COMERPRODUCTS IDE-DRAWVAPORSL iquid boiling above 800 F (427 C) does not vaporizeand exits from the bottom of the column (Figure 5).

8 Inside the distilling column are trays with perforationsin them. The perforations permit the vapors to risethrough the column. When the crude liquid/vaporcharge reaches the inside of the distilling column, gravitycauses the denser (heavier) liquid to drop toward thecolumn bottom, but the less dense (lighter) vapors startmoving through the trays toward the perforations in the trays are fitted with a devicecalled bubble caps (Figure 6). The bubble caps forcethe vapor coming up through the trays to bubble throughthe liquid standing several inches deep on that tray. Thisbubbling is essential for the distilling operation. Thehot vapor bubbles through the liquid and transfers heatto the liquid during the bubbling. As the vapor bubblescool, some of the hydrocarbons in the bubbles willchange from vapor to a liquid state. As heat transfersfrom vapor to a liquid, the temperature of the vapordrops. The lower temperature of the liquid causes someof the compounds in the vapor to condense the gas has passed through the liquid and shedssome of the heavier hydrocarbons, the vapor thenmoves up to the next tray where the same process takesplace.

9 The amount of liquid on each tray grows as someof the hydrocarbons from the vapor are stripped out. Adowncomer is installed to permit excess liquid to over-flow to the next lower tray. This cycle is continuous andrepetitive. Some of the molecules in the compoundsmake several round trips: up a couple of trays as vapor,finally condensing, then down a few trays via thedowncomer as a liquid (Figure 7). This mixing of liquid/vapor creates the several levels on the column, sidedraws take theliquid-distilled product off the lighter products (lowerboiling points) from the top of the column, and theheavier liquids (higher boiling points) toward the bot-tom (see Fig. 8).Figure 8: Distilling SidedrawsBUTANE AND LIGHTERSTRAIGHT-RUN GASOLINENAPHTHAKEROSENELIGHT GAS OILHEAVY GAS OILSTRAIGHT-RUN RESIDUECRUDE OIL9 Flowserve Corporation, Flow Control Division, Valtek Control Productswith positioners (such as Valtek Mark One globe valves)are generally used in applications requiring 4-inch (DN100) and smaller valves.

10 When 6-inch (DN 150) andlarger valves are required, rotary valves (such as theValtek MaxFlo eccentric plug valve) are commonly used,because they are inherently less valves are also less susceptible to packing leaksand should be considered when strict environmentalregulations are in Valve Applications VAC/ATM Residue VGO/AGO/LDO/HDO/AR/VR Pumparounds Bottoms Pump Recirculation Fuel Gas Block and Bleed Furnace Fuel Gas Furnace Pass Flow Control Exchanger Bypass Product and Unit Tower Cuts Stripping Steam Flow Control Crude Tower Pumparounds Mixing SystemsFigure 10: Distilling Crude and ProductDispositionFigure 9: Reboil and RefluxSeveral Processes are designed outside the distillingcolumn to facilitate the operation. To assure purity andto eliminate carry-over, a portion of the vapor will berun through a cooler. Condensed liquid is reintroducedto a lower tray, while remaining vapor is sent off as prod-uct to the distillation column.