**Investigation of Cold-flow Properties of Diesel Fuel**

**National Research Tomsk Polytechnic University**

Institute of Natural Resources

Galina Y. Silko

Nataliya S. Belinskaya

Institute of Natural Resources

Galina Y. Silko

Nataliya S. Belinskaya

Urgency and aim of research

Hydrodewaxing process flow sheet

Cold-flow properties of diesel fuel

Thermodynamic characteristics of reactions

Kinetic model of hydrodewaxing process

Influence of technological conditions

Optimum performance of process

Diesel fuel production

Addition of light fractions to diesel oil.

Addition of depressor additives.

Cold flow properties can be decreased by change of hydrocarbon composition -

hydrodewaxing process

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THE AIM OF THE PRESENT WORK

Urgency of Research

Composition of raw materials

Hydrodewaxing process flow sheet

RAW MATERIALS:

Gasoline from hydrorefining

Gasoline from visbreaking

Middle distillates

Atmospheric gas oil

PROCESS CONDITIONS:

P-1 (hydrorefining reactor):

P=9.0 MPa, T=313 – 361 °C, Vkat=150 m3, kat: NiO-MoO3

P-2 (hydrorefining reactor):

P=8.8 MPa, T=338-398 °C, Vkat=151.2 m3, kat: NiO-MoO3

P-3 (hydrodewaxing reactor):

P=8.4 MPa, T=345-405 °C, Vkat=150 m3, kat: CoO-MoO3

PRODUCTS:

Gasoline

Petroleum gas

Diesel fractions 180 – 240 °C

Diesel fractions 240 – 340 °C

Fractions >340 °C

Formalized conversion scheme of hydrocarbons

Quantum-chemical methods

(program Gaussian)

DFT – Density Functional Theory,

B3LYP, basis 3-21G,

T=375 °C, P=6.9 MPa

Thermodynamic Characteristics of Reaction

Kinetic Model of Hydrodewaxing

Process

General view of kinetic model equations:

v – stoichiometric coefficient in corresponding reaction, Wj – rate of j-th reaction.

Kinetic Model of Hydrodewaxing

Process

General view of kinetic model equations:

v – stoichiometric coefficient in corresponding reaction, Wj – rate of j-th reaction.

Specific Reaction Rate

Influence of Temperature on Process

Increase of 60 °C in process temperature

CONCLUSION

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is to investigate cold-flow properties of diesel fuel using developed computer modelling system of hydrodewaxing process.

The

Cloud Point

is the temperature at which paraffin begins to form cloudy wax crystals.

The

Pour Point

is the temperature at which the paraffin in the fuel has crystallized to the point where the fuel gels and becomes resistant to flow.

The

Cold-filter plugging point

is the highest temperature at which a certain amount of fuel does not pass through a standard filter the set time under standard under cooling.

Two main reactions:

hydrocracking of high molecular isomerization of normal

weight linear paraffins C10–C27 paraffins

paraffins

naphthenes

aromatic hydrocarbons

unsaturated hydrocarbons

Melting point of n-paraffin and i-paraffin hydrocarbons

Solid phase sediment from diesel fuel

Hydrocarbons with

asymmetric branched structure

Hydrocarbons with

normal structure

During the hydrodewaxing process constant decrease in diesel fuel pour point is observed :

raw material – 1 °C,

hydrotreated feed (after 2 reactor) – minus 18 °C

isomerizate (after 3 reactor) – minus 25 °C.

CONCLUSION

content of n-paraffins C10 – C27 reduces by 2.18 % wt.

amount of i-paraffins increases by 1.06 % wt.

rate of hydrocracking reaction increases four-fold

rate of izomerization reaction increases two-fold

Cold flow properties of diesel fuels was investigated;

Computer modelling system of hydrodewaxing process was created;

Using the created mathematical model the influence of hydrogen gas flow rate and temperature on the yield of high-paraffins and iso-paraffins in the product was investigated.

Content of n-paraffins C10 – C27 in the product mixture decreases, which promotes improvement of cold-flow properties of diesel fuels.

The composition of raw material includes:

normal paraffin hydrocarbons C10–C27 with about 16.12 wt.%.

Content of n-paraffins C10–C27 after the third (hydrodewaxing) reactor is 10.17 wt.%.