HDS-1Low Sulfur Gasoline Project

General OverviewGeneral Overview

Introduction

The purpose of FCCU Gasoline The purpose of FCCU Gasoline Hydrodesulfurization (HDS-1), as part of the Low Hydrodesulfurization (HDS-1), as part of the Low Sulfur Gasoline Project, is to reduce the sulfur Sulfur Gasoline Project, is to reduce the sulfur content of the FCCU Naphtha to a combined content of the FCCU Naphtha to a combined sulfur content of 30 ppmw. sulfur content of 30 ppmw.

FCCU gasoline makes up over 50% of the FCCU gasoline makes up over 50% of the gasoline pool at Convent and currently contains gasoline pool at Convent and currently contains ~1200 ppmw sulfur . ~1200 ppmw sulfur .

Introduction (cont.)

HDS-1 will enable Convent Refinery’s gasoline HDS-1 will enable Convent Refinery’s gasoline pool to meet the Federally mandated Tier II sulfur pool to meet the Federally mandated Tier II sulfur specification for gasoline sold at the pumps. specification for gasoline sold at the pumps.

In 2004, the maximum sulfur allowed in any In 2004, the maximum sulfur allowed in any gasoline blend will be 300 ppmw, and Motiva gasoline blend will be 300 ppmw, and Motiva must meet a Corporate average of <120 ppmw. must meet a Corporate average of <120 ppmw.

In 2006, the maximum sulfur allowed in any In 2006, the maximum sulfur allowed in any gasoline blend will be 80 ppmw, and Motiva must gasoline blend will be 80 ppmw, and Motiva must meet a Refinery average of <30 ppmw.meet a Refinery average of <30 ppmw.

Background

The Low Sulfur Gasoline (LSG) Project began in 1999.The Low Sulfur Gasoline (LSG) Project began in 1999. CDTech Catalytic Distillation Technology was chosenCDTech Catalytic Distillation Technology was chosen for for

the project. the project. The Motiva Convent design is part of a centrally managed The Motiva Convent design is part of a centrally managed

project to provide Port Arthur, Convent, Puget Sound, project to provide Port Arthur, Convent, Puget Sound, Norco, and Deer Park with processing facilities to produce Norco, and Deer Park with processing facilities to produce low sulfur gasoline.low sulfur gasoline.

Bechtel was chosen to provide FEL and detailed engineering Bechtel was chosen to provide FEL and detailed engineering for ISBL. Bechtel was also chosen to provide CM for ISBL for ISBL. Bechtel was also chosen to provide CM for ISBL & OSBL& OSBL

Jacobs Engineering was chosen to provide FEL and detailed Jacobs Engineering was chosen to provide FEL and detailed engineering for OSBL (including CWT#4).engineering for OSBL (including CWT#4).

HDS-1 Feed

Debutanizer bottoms from the FCCU Debutanizer bottoms from the FCCU (Full range naphtha)(Full range naphtha)

Cold Feed from Tankage (offspec tank will Cold Feed from Tankage (offspec tank will be 20D-5)be 20D-5)

Modes of Operation

The HDS-1 unit is designed for two modes of operation:The HDS-1 unit is designed for two modes of operation: Case 2 describes the base case where HTU-3 is running in Case 2 describes the base case where HTU-3 is running in

gas oil hydrotreating mode. In Case 2, HDS-1 feed is gas oil hydrotreating mode. In Case 2, HDS-1 feed is expected to contain 1000 –1300 ppmw Sulfur.expected to contain 1000 –1300 ppmw Sulfur.

Case 3 describes the case where HTU3 is down, or not Case 3 describes the case where HTU3 is down, or not operating in gas oil mode, and is designed for an HDS-1 operating in gas oil mode, and is designed for an HDS-1 feedstock with a higher sulfur content (up to 1732 ppmw feedstock with a higher sulfur content (up to 1732 ppmw by design). by design). The unit design for both cases will desulfurize FCCU The unit design for both cases will desulfurize FCCU naphtha feed with high purity hydrogen to meet the 30 naphtha feed with high purity hydrogen to meet the 30 ppmw sulfur spec in the combined products.ppmw sulfur spec in the combined products.

Charge Rates

HDS-1 is designed to charge up to 57,000 BPSD of HDS-1 is designed to charge up to 57,000 BPSD of full range FCCU naphtha.full range FCCU naphtha.

This charge rate includes up to 9,000 BPSD of cold This charge rate includes up to 9,000 BPSD of cold feed from tankage (20D-5).feed from tankage (20D-5).

HDS-1 does not have a charge heater, so the heat HDS-1 does not have a charge heater, so the heat balance of the unit dictates the amount of cold charge balance of the unit dictates the amount of cold charge that can be fed (~15% cold feed).that can be fed (~15% cold feed).

Design turndown of the unit is 50% of the design Design turndown of the unit is 50% of the design charge or 28,500 BPSD. This turndown limit will be charge or 28,500 BPSD. This turndown limit will be tested after start-up.tested after start-up.

Hydrogen

Hydrogen is utilized to remove the sulfur in the Hydrogen is utilized to remove the sulfur in the FCCU naphtha feed.FCCU naphtha feed.

Fresh make-up hydrogen from the hydrogen Fresh make-up hydrogen from the hydrogen pipeline is introduced through several injection pipeline is introduced through several injection points to the unit.points to the unit.

In Case 2, Hydrogen usage is estimated to be In Case 2, Hydrogen usage is estimated to be 10.03 MMSCFD.10.03 MMSCFD.

In Case 3, Hydrogen usage is estimated to be In Case 3, Hydrogen usage is estimated to be 10.61 MMSCFD.10.61 MMSCFD.

Hydrogen (cont.)

A hydrogen purge operation is also employed to A hydrogen purge operation is also employed to maintain hydrogen partial pressure required for the maintain hydrogen partial pressure required for the treating process.treating process.

The unit produces a low-pressure and a high-pressure The unit produces a low-pressure and a high-pressure purge gas stream from the amine scrubbers, as well as purge gas stream from the amine scrubbers, as well as a low-pressure purge stream from the CDHydro Reflux a low-pressure purge stream from the CDHydro Reflux Drum. Drum.

Combined, the streams are >70% hydrogen and ~150 Combined, the streams are >70% hydrogen and ~150 MSCFH and will be routed to the refinery East-side MSCFH and will be routed to the refinery East-side fuel gas system. fuel gas system.

Alternate line-ups include the flare.Alternate line-ups include the flare.

Other Inputs

600# Steam for three column reboilers600# Steam for three column reboilers Fuel Gas and Natural Gas for the Fired Fuel Gas and Natural Gas for the Fired

ReboilerReboiler Lean Amine for the two Amine Absorbers Lean Amine for the two Amine Absorbers

(one high pressure and one low pressure)(one high pressure and one low pressure) DMDS (located in a storage vessel on the DMDS (located in a storage vessel on the

unit) for injection when the Recycle Gas unit) for injection when the Recycle Gas Compressor is not operating.Compressor is not operating.

Other Effluent Streams

Rich Amine routed to ARU2/3/4 for Rich Amine routed to ARU2/3/4 for RegenerationRegeneration

Sour Water collected from various drums in Sour Water collected from various drums in the unit and routed to the Sour Water the unit and routed to the Sour Water Strippers.Strippers.

HDS-1 Products

Light Cat Naphtha (LCN) – a side draw Light Cat Naphtha (LCN) – a side draw product from the CDHydro Naphtha Splitter product from the CDHydro Naphtha Splitter towertower

Stabilized Naphtha – bottom product from Stabilized Naphtha – bottom product from the Naphtha Stabilizer tower.the Naphtha Stabilizer tower.

The LCN will be “sponged” with Stabilized The LCN will be “sponged” with Stabilized Naphtha, as needed for RVP control, as Naphtha, as needed for RVP control, as final product leaving the unit. final product leaving the unit.

Some Affected Areas of HDS-1

The FCCU will decommission equipment downstream of the The FCCU will decommission equipment downstream of the Debutanizer and have a new gum inhibitor injection skid.Debutanizer and have a new gum inhibitor injection skid.

The TAME Depentanizer will receive LCN from HDS-1 as The TAME Depentanizer will receive LCN from HDS-1 as feed instead of LFC from the FCCU.feed instead of LFC from the FCCU.

HTU-1 will supply catalyst preparation material in the form of HTU-1 will supply catalyst preparation material in the form of hydrotreated naphtha and low sulfur avjet.hydrotreated naphtha and low sulfur avjet.

Several tanks in PUL have been taken over by HDS-1, for Several tanks in PUL have been taken over by HDS-1, for products and offspec material (Tanks 20D-26/66/25/65 and 5).products and offspec material (Tanks 20D-26/66/25/65 and 5).

HDS-1 is tied to Flare 4.HDS-1 is tied to Flare 4. Purge Gas from HDS-1 will be routed to the East Side Refinery Purge Gas from HDS-1 will be routed to the East Side Refinery

Fuel Gas Drum.Fuel Gas Drum.

HDS-1 Low Sulfur Gasoline Project

Process DescriptionProcess Description

Basic Operation

The function of the HDS-1 unit is to The function of the HDS-1 unit is to desulfurize the FCCU Naphtha while desulfurize the FCCU Naphtha while minimizing the amount of olefin saturation, minimizing the amount of olefin saturation, using CDTech Technology.using CDTech Technology.

CDHydro Naphtha Splitter

The CDHydro Column:The CDHydro Column: Receives 1000-1732 ppmw sulfur feed from the Receives 1000-1732 ppmw sulfur feed from the

FCCU and tankage. FCCU and tankage. Processes FCCU gasoline to produce and Processes FCCU gasoline to produce and

overhead C6 and lighter stream (LCN) that overhead C6 and lighter stream (LCN) that contains ~35 ppmw sulfur and a bottoms stream contains ~35 ppmw sulfur and a bottoms stream that contains 1500-2500 ppmw sulfur.that contains 1500-2500 ppmw sulfur.

Uses Pipeline hydrogen to enhance reaction rates.Uses Pipeline hydrogen to enhance reaction rates.

CDHydro Design

The CDHydro Column consists of 32 valve The CDHydro Column consists of 32 valve trays, 3 chimney trays, and 2 sections of catalyst trays, 3 chimney trays, and 2 sections of catalyst packing (a Nickel bed and a Palladium bed). packing (a Nickel bed and a Palladium bed).

The CDHydro Column is a 143’ tall, 15’6” The CDHydro Column is a 143’ tall, 15’6” diameter reaction-distillation column. This diameter reaction-distillation column. This column has a skirt of ~50’, which brings the column has a skirt of ~50’, which brings the total height to almost 200’. total height to almost 200’.

CDHydro Split

The feed with high olefins content flashes The feed with high olefins content flashes up the column, via a temperature controller up the column, via a temperature controller that controls heat input into the column. that controls heat input into the column.

On the way up the tower, these lighter On the way up the tower, these lighter products interact with hydrogen injected products interact with hydrogen injected into the tower to cause 3 chemical into the tower to cause 3 chemical reactions.reactions.

CDHydro Reactions

Thioetherification:Thioetherification: where mercaptans and olefins where mercaptans and olefins react to form disulfides (a stable heavy sulfur react to form disulfides (a stable heavy sulfur compound) which distills into the bottoms.compound) which distills into the bottoms.

Diene hydrogenation:Diene hydrogenation: where diolefins react with where diolefins react with hydrogen to form olefins. This reaction creates the hydrogen to form olefins. This reaction creates the reactants for the next step.reactants for the next step.

Hydroisomerization:Hydroisomerization: where the double bonds in where the double bonds in olefin molecules move to a different location in olefin molecules move to a different location in the same molecule, causing an octane boost.the same molecule, causing an octane boost.

CDHydro Products

The LCN product (a C6 and lighter stream) is drawn The LCN product (a C6 and lighter stream) is drawn from Tray 6, the chimney tray above the catalyst from Tray 6, the chimney tray above the catalyst packing, and contains ~35 ppmw sulfur by design (<5 packing, and contains ~35 ppmw sulfur by design (<5 ppm mercaptans). ppm mercaptans).

The LCN product is cooled, then mixed with Stabilized The LCN product is cooled, then mixed with Stabilized Naphtha product to reduce vapor pressure, before it is Naphtha product to reduce vapor pressure, before it is sent OSBL to the TAME Depentanizer for further sent OSBL to the TAME Depentanizer for further processing or to product tankage (Tanks 20D-26/66).processing or to product tankage (Tanks 20D-26/66).

The CDHydro bottoms (1500-2500 ppmw sulfur at this The CDHydro bottoms (1500-2500 ppmw sulfur at this point) are further treated in the CDHDS and Polishing point) are further treated in the CDHDS and Polishing Reactor systems.Reactor systems.

CDHDS Column

The CDHDS Column:The CDHDS Column: Receives the CDHydro bottoms as feed.Receives the CDHydro bottoms as feed. Processes the CDHydro bottoms to produce a C7 Processes the CDHydro bottoms to produce a C7

and heavier heavy naphtha stream that contains and heavier heavy naphtha stream that contains 120-150 ppmw sulfur.120-150 ppmw sulfur.

Uses recycle hydrogen provided by the Recycle Uses recycle hydrogen provided by the Recycle Gas Compressor as well as pipeline hydrogen Gas Compressor as well as pipeline hydrogen injected into the catalyst beds and reboiler inlet to injected into the catalyst beds and reboiler inlet to achieve proper reaction rates and reduce heater achieve proper reaction rates and reduce heater fouling.fouling.

CDHDS Design

The CDHDS Column consists of five individually The CDHDS Column consists of five individually supported catalyst beds (all Cobalt-Molybdenum), supported catalyst beds (all Cobalt-Molybdenum), a section of structured packing and a liquid a section of structured packing and a liquid distributor above the top catalyst bed, a liquid distributor above the top catalyst bed, a liquid distributor and chimney tray above each of the distributor and chimney tray above each of the remaining four catalyst beds, and a chimney-liquid remaining four catalyst beds, and a chimney-liquid collector tray below the bottom bed. collector tray below the bottom bed.

The CDHDS Column is a 133’ tall, 15’6” The CDHDS Column is a 133’ tall, 15’6” diameter reaction-distillation column.diameter reaction-distillation column.

CDHDS Split

The feed enters the column as ~40% vapor. Using a The feed enters the column as ~40% vapor. Using a temperature controller that controls heat input into temperature controller that controls heat input into the column, 80% of the feed is taken overhead and the column, 80% of the feed is taken overhead and the remaining 20% exits the column as bottoms. the remaining 20% exits the column as bottoms.

This 80:20 overhead to bottom ratio splits the This 80:20 overhead to bottom ratio splits the sulfur evenly between the upper and lower catalyst sulfur evenly between the upper and lower catalyst beds and concentrates the heaviest sulfur in the beds and concentrates the heaviest sulfur in the bottoms beds to be exposed to the highest reaction bottoms beds to be exposed to the highest reaction temperatures.temperatures.

CDHDS Reactions

Hydro-Desulfurization (HDS):Hydro-Desulfurization (HDS): where sulfur is where sulfur is removed from hydrocarbon molecules by removed from hydrocarbon molecules by converting it to Hconverting it to H22S. This is a desired reaction in S. This is a desired reaction in the CDHDS column and Polishing Reactor in order the CDHDS column and Polishing Reactor in order to produce a low sulfur heavy gasoline stream.to produce a low sulfur heavy gasoline stream.

Olefin Saturation:Olefin Saturation: where the double bond in a where the double bond in a hydrocarbon molecule is converted to a single hydrocarbon molecule is converted to a single bond by the addition of hydrogen. This is an bond by the addition of hydrogen. This is an undesired reaction in the CDHDS column and undesired reaction in the CDHDS column and Polishing Reactor. Polishing Reactor.

Recycle Hydrogen

Vapors from the CDHDS Overhead system Vapors from the CDHDS Overhead system are treated in the Recycle Gas Amine are treated in the Recycle Gas Amine Absorber.Absorber.

They are then routed to the Recycle Gas They are then routed to the Recycle Gas Compressor Knock Out Drum where it is Compressor Knock Out Drum where it is recycled back to the CDHDS column recycled back to the CDHDS column reboiler inlet via the Recycle Gas reboiler inlet via the Recycle Gas Compressor. Compressor.

Reboiler Furnace

The Reboiler for the CDHDS column is a The Reboiler for the CDHDS column is a Fired Heater, the only one on the unit.Fired Heater, the only one on the unit.

The Reboiler has 4 parallel passes, and 8 The Reboiler has 4 parallel passes, and 8 fired burners. fired burners.

The boil-up, regulated by the flow of fuel The boil-up, regulated by the flow of fuel gas, is controlled by a temperature gas, is controlled by a temperature controller on the CDHDS column.controller on the CDHDS column.

CDHDS Products

The CDHDS Column overhead stream is The CDHDS Column overhead stream is condensed, cooled, and collected in a series of condensed, cooled, and collected in a series of overhead drums and coolers.overhead drums and coolers.

Some of the liquid collected from the overhead is Some of the liquid collected from the overhead is fed back to the column as reflux, and the rest is fed back to the column as reflux, and the rest is fed to the Hfed to the H22S Stripper.S Stripper.

The CDHDS Column bottoms stream can be The CDHDS Column bottoms stream can be routed to the Reboiler Furnace, to the Polishing routed to the Reboiler Furnace, to the Polishing Reactor, to the Polishing Reactor Feed Heater, or Reactor, to the Polishing Reactor Feed Heater, or to the Naphtha Stabilizer (Pol. Rx. Bypass). to the Naphtha Stabilizer (Pol. Rx. Bypass).

H2S Stripper Design

In the HIn the H22S Stripper, 26 valve trays remove S Stripper, 26 valve trays remove dissolved Hydrogen, light hydrocarbons, and Hdissolved Hydrogen, light hydrocarbons, and H22S S from the desulfurized CDHDS overhead. from the desulfurized CDHDS overhead.

The Stripper is designed to strip HThe Stripper is designed to strip H22S in the CDHDS S in the CDHDS overhead to less than 5 ppmw prior to entering the overhead to less than 5 ppmw prior to entering the Polishing Reactor.Polishing Reactor.

Vapors from the HVapors from the H22S Stripper and Naphtha S Stripper and Naphtha Stabilizer Reflux Drums are routed to the Vent Gas Stabilizer Reflux Drums are routed to the Vent Gas Amine Absorber for treatment prior to entering the Amine Absorber for treatment prior to entering the refinery fuel gas system. refinery fuel gas system.

H2S Stripper – Preparing the Polishing Reactor Feed

The HThe H22S Stripper is an essential element in preparing S Stripper is an essential element in preparing the CDHDS overhead liquid for further reaction in the the CDHDS overhead liquid for further reaction in the Polishing Reactor as this stream makes up 80% of Polishing Reactor as this stream makes up 80% of Polishing Reactor feed.Polishing Reactor feed.

Since olefins are present in the Polishing Reactor feed, Since olefins are present in the Polishing Reactor feed, free Hfree H22S in the feed could combine with the olefins to S in the feed could combine with the olefins to form mercaptans through form mercaptans through Mercaptan Recombination. Mercaptan Recombination.

Olefins that react with HOlefins that react with H22S in the Polishing Reactor are S in the Polishing Reactor are removed from the gasoline product with an associated removed from the gasoline product with an associated loss of octane. loss of octane.

Polishing Reactor Design

The Polishing Reactor is a 19’6” tall fixed The Polishing Reactor is a 19’6” tall fixed bed reactor with a 10’ diameter.bed reactor with a 10’ diameter.

The Polishing Reactor receives feed from The Polishing Reactor receives feed from the Hthe H22S Stripper and the CDHDS Column S Stripper and the CDHDS Column bottoms. bottoms.

Hydrogen is injected into the feed upstream Hydrogen is injected into the feed upstream of the Polishing Reactor feed/effluent of the Polishing Reactor feed/effluent exchangers.exchangers.

Polishing Reactor

The feed passes through the Polishing Reactor’s The feed passes through the Polishing Reactor’s single Cobalt-Molybdenum fixed catalyst bed, to single Cobalt-Molybdenum fixed catalyst bed, to reduce the sulfur content from 120-150 ppmw reduce the sulfur content from 120-150 ppmw down to ~28 ppmw by design.down to ~28 ppmw by design.

The Polishing Reactor bottoms are routed through The Polishing Reactor bottoms are routed through the Polishing Reactor Hot/Cold Separator System, the Polishing Reactor Hot/Cold Separator System, where a recycle Hydrogen stream is produced and where a recycle Hydrogen stream is produced and routed to the CDHDS Column feed stream. routed to the CDHDS Column feed stream.

The liquids collected in the Hot and Cold The liquids collected in the Hot and Cold Separators are routed to the Naphtha Stabilizer.Separators are routed to the Naphtha Stabilizer.

Naphtha Stabilizer

The Naphtha Stabilizer :The Naphtha Stabilizer : Receives feed from the Polishing Reactor Hot and Receives feed from the Polishing Reactor Hot and

Cold Separators.Cold Separators. Uses a 600# steam reboiler to strip dissolved Uses a 600# steam reboiler to strip dissolved

hydrogen, Hhydrogen, H22S, and light hydrocarbon from the S, and light hydrocarbon from the heavy gasoline product. heavy gasoline product.

Naphtha Stabilizer bottoms are cooled and used to Naphtha Stabilizer bottoms are cooled and used to sponge the LCN product for vapor pressure sponge the LCN product for vapor pressure control, before being sent to product tankage control, before being sent to product tankage (Tanks 20D-25/65) as Stabilized Naphtha Product.(Tanks 20D-25/65) as Stabilized Naphtha Product.

LSG Project Fast Facts

ISBL has about 108 pieces of mechanical equipmentISBL has about 108 pieces of mechanical equipment OSBL has about 29 pieces of mechanical equipment OSBL has about 29 pieces of mechanical equipment

including the CWTincluding the CWT Total cubic yards of concrete = 2,590 cu ydsTotal cubic yards of concrete = 2,590 cu yds Total tons of steel = 1,180 tonsTotal tons of steel = 1,180 tons Total linear feet of pipe = 127,000 ft (24.1 miles)Total linear feet of pipe = 127,000 ft (24.1 miles) Total linear feet of cable tray = 5,490 ft (1.0 miles)Total linear feet of cable tray = 5,490 ft (1.0 miles) Total linear feet of cable = 283,500 ft (53.7 miles)Total linear feet of cable = 283,500 ft (53.7 miles)