Done by:-

Abdulaziz Al-RashidiFaisal Al-AzmiKhalaf Al-AzmiMohammed Al-AzmiNawaf Al-Azmi

Supervised by: Prof. Mohamed Fahim Eng. Yusuf Ismail

Outline:

Introduction History World production and consumption Uses Feedstocks and products Reactions involved Reactor’s design Catalyst Modes of operation Process variables Basic economy Conclusion

Introduction:

The interest of using the hydrocracking has been caused by several factors:

1. High demand for gasoline, diesel, and jet fuel.2. Hydrogen is available at low cost and in large amounts.3. Environmental concerns limiting sulfur and aromatic

compound concentration in motor fuels have increased.

Advantages of hydrocracking:

1. Better balance of gasoline and distillate production

2. Greater gasoline boiling-range naphtha yields

3. Improved gasoline pool octane quality and sensitivity

4. Production of relatively high amounts of isobutane in the butane fraction

5. Supplementing of fluid catalytic cracking to upgrade heavy cracking stocks, aromatics, cycle oils, and coker oils to gasoline, jet fuels, and diesel.

6. Improves combustion quality of product.

History:

Hydrocracking is one of the oldest hydrocarbon conversion processes.

Hydrocracking technology was developed in Germany between 1915 and 1945.

The first plant for hydrocracking of brown coal was in Germany in 1927.

In 1960s, the automobile industry was an important factor to develop hydrocracking processes.

The early 1970s saw a continuation of the rapid growth of hydrocracking in the United States.

Because of the increasing demand on hydrocracking products the process spread widely in the 1980s and early 1990s

World production and consumption

Uses of Naphtha:

Feedstock for producing high octane gasoline. Industrial solvents and cleaning fluids In the home cleaning fluid An oil painting medium An ingredient in shoe polish An ingredient in some lighter fluids A fuel for portable stoves and lanterns As a coating for elemental lithium metal, to prevent oxidation As a fuel in gas turbine unit As the working fluid in the naphtha engine.

Feedstocks and products

. Feed Products

1. Kerosene Naphtha

2. Straight –run diesel Naphtha and / or jet fuel

3. Atmospheric gas oil Naphtha, jet fuel and / or diesel

4. Vacuum gas oil Naphtha, jet, diesel, lube oil

5. FCC LCO Naphtha

6. FCC HCO Naphtha and/or distillates

7. Coker LCGO Naphtha and/or distillates

8. Coker HCGO Naphtha and/or distillates

Reactions involved:

Major routes of hydrocracking reactions:1. Noncatalytic:

thermal cleavage of C-C bonds via hydrocarbon radicals, with hydrogen addition.

2. Monofunctional:

C-C bond cleavage with hydrogen addition over hydrogenation components consisting of metals (Pt, Pd, Ni), oxides, or sulfides.

3. Bifunctional

C-C bond cleavage with hydrogen addition over bifunctional catalysts consisting of a hydrogenation component dispersed on a porous, acidic support. In petroleum refining, most hydrocracking reactions follow this route.

In most hydrocracking processes, the feedstock is

submitted to hydrotreating prior to hydrocracking, in

the same or in different reactors.

Reactions occurring mostly during hydrotreating:

1. Hydrodesulfurization (HDS)

2. Hydrodeoxygenation (HDO)

3. Hydrodenitrogenation (HDN)

4. Olefin hydrogeneration

5. Partial aromatics hydrogenation

Reactions occurring mostly during hydrocracking:

1. Monoaromatics hydrogenetionconvert the double bounds in benzene ring to single bound

2. Hydrodealkylationcracked the side chain of cycle compound

3. HydrodecyclizationNaphtha ring opening

4. Isomerization of paraffins Alteration of the arrangement of atoms in a molecule without changing the number of atoms

C

300o C |

C – C – C – C C – C – C

Straight Chain AlCl3 Branched chain

Reactor’s design:

The reactors used in hydrocracking processes are

downflow, fixed-bed catalytic reactors.

The reactors are normally carried out at average

catalyst temperatures between 550 and 750°F (290 and

400°C) and at reactor pressures between 1200 and

2200 psig (8,275 and 15,200 kPa)

Modes of operation:

The hydrocracking processes are designed to upgrade a variety of petroleum feedstocks by adding hydrogen and cracking to a desired boiling range.

The feedstocks used in hydrocracking processes contain sulfur, nitrogen, and oxygen. These compounds have a negative effect on hydrocracking catalysts, and require hydrotreatment prior to contact with the hydrocracking catalyst. For that reason, most of the hydrocracking processes involve both hydrotreating and hydrocracking steps.

The processes used in hydrocracking can be divided into three major categories: single-stage, two-stage and once-through.

Single-Stage Recycle Hydrocracking:

The simplest configuration of hydrocracking process It may contains single reactor or two reactors in series It is used to maximize diesel products with amorphous catalyst The reactor operates at temperatures varying from 300 to 450°C (570-

840°F), and hydrogen pressures between 85 and 200 bar (1250-2915 psig).

The effluent from the first reactor is not subjected to intermediate vapor/liquid separation and fractionation prior to being passed into the second reactor.

For feeds with relatively low endpoints, a single-stage recycle configuration is commonly used to achieve total conversion. However, such a configuration can be less selective for liquid product than a two-stage configuration because all conversion must be accomplished in a single stage.

once-through process

In the once-through process the unconverted oil resulting from the first pass is not recycled.

The fractionator bottoms are used as steam cracker feed, FCC feed, or lube oil base.

However, middle distillates made by this process are generally higher in aromatics and are therefore of poorer burning quality than those produced by recycle hydrocracking.

This process is carried out in low temperature and in low hydrogen partial pressure since the conversion of the heaviest molecules in the feedstock is not required

Lower capital cost Catalyst deactivation is reduced by the elimination of the recycle

stream

Two-Stage Recycle Hydrocracking:

A widely used hydrocracking process configuration is the two-stage process, which allows a larger throughput (higher feed rates) than the single-stage process.

It Contains three reactors: First reactor is for hydrotreating Second reactor is for partially hydrocracking The Third reactor is used to totally hydrocrack (unconverted oil). The conversion in R-1 and R-2 represents the first stage of the process, whereas the conversion

in R-3 represents the second stage of the process

The first and second reactors in the two-stage configuration use the same catalysts as in single-stage configuration. The hydrocracking catalyst in the third reactor use either noble metal or base metal sulfide hydrocracking catalysts because of the absence of N and S. The base metal sulfide catalysts are most frequently used.

The hydrocracking in the second stage can be carried out at lower temperature than in the first stare due to the absence of ammonia in reaction environment. Thus, first-stage hydrocracking temperatures are in the range of 300-450°C (570-840°F), whereas second-stage hydrocracking temperatures are in the range of 270-370°C (520-700°F)

Comparison between process modes:

Mode of operation Single-stage recycle Two-stage Once through

Advantages Low capital investment

Used for feeds with low end points to achieve total conversion

More product yield flexibility

Use different catalyst each stage

Complete hydrogenation of the product with reduction in aromatics and increase smoke point

Lower temperature and lower hydrogen partial pressure

Longer catalyst life because of the absence of the recycle

Lower capital cost

Disadvantages Less selective for liquid product

Used for low capacity plants

High capital investment

High severity Less flexibility Lower quality of

products High aromatic

content

Product Qualities:

Specification

PRODUCTS

Naphtha Jet fuel/kersone H. Pour

Diesel

Fract.

Btms.

Gravity API 58.8 37.1 33.9 33

Sulfur

PPM / %wt

15 14 16.0 100

Nitrogen,

PPM

0.1 2.4 0.5 1.0

Dist. Range , Deg. 106 – 330 350 – 560 410 – 730 570 – 960

Flash Point , Deg. -- 160 206 --

Smoke Point , MM -- 19 -- --

Pour Point , Deg -- -- 40 95

Freezing Point , Deg -- ( - ) 50 -- --

Catalyst

Spent catalyst:

  All catalyst that cannot be used farther even after

regeneration will be replaced and this type of catalyst is known as spent catalyst. The spent catalyst will be backed in drums and sealed in drums the catalyst will be send back to the supplier so that proper disposal can take place. The life time of the catalyst in our process is five years.

Regeneration of catalyst:

Regeneration of catalyst during normal operation of catalyst there will be deposition of coke on its surface. This coke deposition will block the active sites of the catalyst and thus the conversion will be reduced greatly. In order to make these sites active again the catalyst has to be regenerated. This usually done by burning of fuel gas or the surface of catalyst so that the carbon on the catalyst surface will be converted to CO2 and thus making the catalyst active again and bring back to its initial conditions. In our process the catalyst regenerated every three months.

Compared between amorphous and zeolite:

The advantages of zeolite are: Greater acidity, resulting in greater cracking activity. Better thermal/hydrothermal stability. Better naphtha selectivity. Better resistance to nitrogen and sulfur compounds. Low coke-forming tendency. Easy regenerability.

Process variables:

Process variables have a significant impact on the conversion, the yield and quality of the resulting products.

The primary reaction variables are reactor temperature and pressure, space velocity, hydrogen consumption, nitrogen content of the feed, and hydrogen sulfide content of the gases.

1-Reactor Temperature:

Reactor temperature is the primary means of conversion control. If the temperature of reactor increase the rate of reaction also increase.

2-Reactor Pressure:

The primary effect of reactor pressure is in its effect on the partial pressures of hydrogen and ammonia. Conversion increases with increasing hydrogen partial pressure and decreases with increasing ammonia partial pressure.

3-Space Velocity:

The space velocity varies directly with feed rate, As the feed rate increases the conversion decreases.

4-Nitrogen Content:

An increase in organic nitrogen content of the feed causes a decrease in conversion.

5-Hydrogen Sulfide:

Hydrogen sulfide at low concentrations act as a catalyst to prevent the saturation of aromatic rings.

Storage tanks:

Tanks for a particular fluid are chosen according to the flash-point of that substance. The naphtha has medium flash point so it stored floating roof -tanks. These tanks are cone roof tanks with a floating roof inside which travels up and down along with the liquid level. This floating roof traps the vapor from fuels.

Basic economy

The price of naphtha vary with time depending on the market demand after some research the prices of the products were obtained through personal contact with KPC and the prices for September 2013 are:

Naphtha 902 $/MT.

Diesel 120 $/Bbl.

Jet fuel 120 $/Bbl.

Basic economy

Basic economy

Conclusion

1- The hydrocracking process is used to convert heavy molecular weight to light molecular weight products.

2- The hydrocracking process include three modes of operation

1.Two stage.

2.Single stage once through.

3.Single stage recycle.

3- It consists of two main types of reactions which are hydrotreating reactions, and hydrocracking reactions.