Petroleum Refining – Chapter 11: Gasoline Production 11-1 Chapter 11 Gasoline Production INTRODUCTION • Convert SR naphtha to motor gasoline stocks through 1. Reforming 2. Isomerization • Production of motor gasoline stocks though 1. Alkylation Isomerization Unit Light Naphtha Crude Coker Hydro/Cat Cracker High Octane Isomerate by transforming straight-chain paraffins (low octane) → isomers (high octane) Catalytic Reformer Heavy Naphtha Crude Coker Hydro/Cat Cracker High Octane Reformate Sold as regular/ premium gasoline Alkylation Unit Olefins i-C 4 Alkylate (high octane) iso-paraffins boiling in the gasoline range Catalyst: Sulfuric or hydrofloric acid Blended into premium motor gasoline & aviation gasoline
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Petroleum Refining – Chapter 11: Gasoline Production
11-1
Chapter 11 Gasoline Production
INTRODUCTION
• Convert SR naphtha to motor gasoline stocks through
1. Reforming
2. Isomerization
• Production of motor gasoline stocks though
1. Alkylation
IsomerizationUnit
Light Naphtha
CrudeCokerHydro/Cat Cracker
High Octane Isomerate
by transforming straight-chain paraffins (low octane) → isomers (high octane)
CatalyticReformer
Heavy Naphtha
CrudeCokerHydro/Cat Cracker
High OctaneReformate
Sold as regular/premium gasoline
AlkylationUnit
Olefins
i-C4Alkylate (high octane)iso-paraffins boiling in the gasoline range .
Catalyst:Sulfuric or
hydrofloric acid
Blended into premium motor gasoline & aviation gasoline
Prof. Tareq A. Albahri 2018 Kuwait University Chemical Engineering
11-2
1. CATALYTIC REFORMING
Introduction
Objective
To increase the octane number of heavy straight run (HSR) naphtha (for motor gasoline
blending) using a catalytic process.
• Catalytic reforming does not change in the IBP and FBP range of naphtha feed.
• Produces large amount of H2 gas that can supplement the refinery H2 system.
• Reforming units can use Platinum (Pt) and Rhenium (Rh) catalysts.
• MAA CCR Platformer uses Platinum (Pt) catalyst.
Capacity
Table 11-1: Catalytic Reforming Units Capacity in Kuwait.
Refinery
Unit
Feed Capacity
(BPD
Reformate
Produced
(BPD)
Octane
Number
(Clear)
MAA CCR Platforming 2X 90
ZOR CCR Platforming
Feed & Product Properties
Table 11-2: Rheniformer Feed and Product Properties.
Fractionator Feed
(total naphtha)
Reformate
API
Sulfur, ppm
N2, ppm
Octane Number (clear)
RVP, psi
Distillation (ºF)
IBP
10%
30
50
70
90
EP
Recovery
65.6
101
4
-
-
126
163
196
221
246
284
316
98
48.6
-
-
95.4
6.2
122
162
217
248
275
313
349
98
Figure 11-1: Catalytic Reforming Unit
Catalytic Reforming Process Description (Figure 11-3)
• The system consists of three reactors, fired heaters, hydrogen recycle system, and
product debutanizing facilities.
• Hydrotreated HSR Naphtha is preheated then vaporized in a fired heater.
• It is mixed with H2 then passed over a catalyst at about 900 ºF and 350 psig in the first
reactor.
• Intermediate heat is provided after first and second reactors because of the
endothermic reactions that reduce the temperature in the reactor.
Petroleum Refining – Chapter 11: Gasoline Production
11-3
• The effluent from the third reactor is cooled, by heating other streams in the unit (for
efficient heat recover) then separated into a liquid product and a H2-rich gas that is
recycled.
• The excess hydrogen which is used as make-up to the refinery hydrotreating system is
bled-off as needed to maintain system pressure.
• A stabilizer is used to remove light gases (C4-) from the reformate product, thus,
control its RVP.
Catalyst & Reactions
• Octane improvement is mainly achieved through
1. Dehydrogenation of naphthenes (low octane) to aromatics (higher octane).
(endothermic)
2. Dehydrocyclization of paraffins (low octane) to aromatics (higher octane).
(slightly endothermic)
3. Isomerization of Paraffins (low octane) to isoparaffins (higher octane).
4. Hydrocracking of heavy paraffins (low octane) to light paraffins (higher octane).
+ 3H2Dehydrogenation
isopropylcyclohexane
ON = 61.1 (clear)
isopropylbenzene
ON = 99.3 (clear)
Toluene
ON = 96.5 (clear)
n-heptane
ON = 0 (clear)
Dehydrocylization4H2+
isomerization
n-octane
ON = -15 (clear)iso-octane
(2,2,4-trimethypentane )
ON = 100 (clear)
n-butane
ON = 89.6 (clear)n-nonane
ON = -20 (clear)
Hydrocracking+
n-pentane
ON = 62.6 (clear)
+ H2
Prof. Tareq A. Albahri 2018 Kuwait University Chemical Engineering