electrodischarge cracking of heavy oil residues

Schematic of reactor ED

The electro-discharge zone is in direct contact with the HC feedstock to be treated, which is fed continuously. Under the influence of high-energy electrons and plasma ions, HC molecules, which are part of the feedstock, undergo degradation and are divided into lower molecular weight compounds.

The effective residence time of the petroleum product in the electrodischarge zone is about 12 microseconds.

Advantages of ED processes

The main advantage of energy conversion under the conditions of electrodischarge processes (EDP) consists in high rates of the cracking reaction. Intensification of cracking processes occurs under the action of high temperature (about 105 K) and high specific power of electric discharges, which lead to the formation of a high concentration of active radicals, ions and electrons.
The electron energy at EPR is about 10 eV, which allows the splitting of hydrocarbons through C-C (6.2 eV) and C-H (5.5 eV) bonds.
Exposure of fuel oil to EAF causes many chemical reactions leading to degradation of high molecular weight compounds of fuel oil, which increases the efficiency compared to thermal cracking.

Electric discharge cracking of tar sands

The unit operates at a raw material temperature of 100-160ºC, power consumption of the reactors 12.5 kW, occupied area of about 5 square meters. The productivity is about 1 t/h.
1- power source;
2- high-voltage wires;
3- electric discharge reactors;
4- pump nsh-100;
5- tank for the initial product;
6- tank for processed product;
7- exhaust hood for gases.

Sequence of tar tar tar processing after ABT in order to obtain maximum amount of light fractions

Treatment of tar sands in an ED reactor at 160oC to obtain processed product and hydrocarbon gas;
Atmospheric distillation of this product with obtaining a fraction of n.k.-360oC, residue and gas. The boiling point was 145oC; The yield of distillate was about 35% and of road bitumen component about 57%.
Distillation of initial tar without ED treatment allowed to obtain about 4.7% of distillate. The boiling start temperature amounted to 270oC.

Block diagram of ED of tar treatment and atmospheric distillation of the obtained product
(conversion to initial tar)

Material balance of EP of tar sands processing
per 1000 kg, kg

Products of tar sands processing and energy costs

At processing of 1000 kg of tar using ER technology can be obtained, kg: 80 - gas, 350 - distillation and 570 - residue.
The distillation after the first distillation complies with the requirements of the specifications for heating oil.
The residue is a component of road bitumen. It has a penetration index of 100 - 150 dmm and ring and ball softening temperature (RST) of 60 - 73oC, it can also be used as a component of delayed coking raw materials.
Energy costs for ER treatment of 1000 kg of tar: power supply consumption of the ER reactor about 12.5 kW, heating of tar (from 25 to 160°C) - 55 kW, pump motor operation - 3 kW. Total: 70.5 kW for processing 1000 kg of tar.

Conclusions on the group composition of fractions

The group composition of distillate shows that the fraction n.k-180оС contains about 30% olefins and 6% dienes. It is these compounds that can polymerize and increase viscosity of the product of fuel oil refining before distillation.
The 181-360оС fraction is free of dienes and contains about 3% of olefins. At the same time, this fraction contains about 40% of linear paraffins and 26% of aromatic compounds.
Sulfur compounds are mainly represented by benz- and dibenzthiophenes derivatives. The sulfur content is distributed as follows, %: 0.57 - gasoline fraction (fl. n.k. - 180оС), 1.16 - diesel fraction (fl. 181-360оС), 2.5 - initial fuel oil M100, 2.6 - residue of distillation of plasma-chemically treated fuel oil M100.

Sequence of tar sands processing after ABT in order to obtain fuel oil M100

Processing of tar sands consisted of the following stages:

Treatment of tar sands in an ER reactor at 160oC to obtain the processed product;
Distillation of gasoline fraction n.a.c.-200оС. As a result of distillation residue-1 is obtained. The gasoline fraction contains a noticeable amount of diene hydrocarbons. This distillation is necessary to increase the stability of the product of tar tar refining in time. Without distillation of the gasoline fraction, viscosity and pour point increase sharply in a few days.
Then from 50% of residue-1 is distilled off the fraction 201-360оС, to obtain residue-2, which is a thermobitumen with penetration of 100-150 dmm and softening point on the ring and ball (CiB) 60-73оС. This 201-360o C distillation is added to the remaining residue-1. The resulting product meets the requirements for M100.

Block diagram for processing tar sands into M100

Scheme for processing tar tar into M100

According to this scheme, the residue-2 (thermobitum) is mixed with the initial tar and the resulting mixture is sent for processing. As a result of realization of this technological scheme from 1000 kg of tar from 1000 kg of tar is obtained about 80 kg of fuel gas (mainly a mixture of limiting and unsaturated hydrocarbons C1-C4), 120 kg of gasoline fraction n.k.-200°С (containing up to 30% of unsaturated hydrocarbons, including dienes) and up to 80% of fuel oil M100. This energy-saving low-temperature atmospheric technological scheme for tar sands processing is an alternative to the widely used visbreaking.

Economic indicators of visbreaking process per 1 ton of feedstock
* provided the tar enters the plant at a temperature of 200-270°C
- Other advantages of electro-discharge technology:
- No metal-intensive equipment;
- no coking;
- relatively low process temperature.

Electrodischarge cracking of vacuum gas oil
(Petromaruz Uzbekistan)

Vacuum gas oil refining sequence

Processing of vacuum gasoil in an ED reactor at 100oC to obtain processed product and hydrocarbon gas;
Atmospheric distillation of this product yielded a fraction of n.k.-360оС, residue and gas. The boiling point was 170oC; The distillate yield was about 40%, 55% residue and 5% hydrocarbon gases. The vacuum distillation residue consists of 22% of the original gasoil (not cracked) and 33% of tar.
Distillation of initial vacuum gasoil without ED treatment allowed to obtain about 4.9% of distillate. The boiling start temperature was 330oC.

Cyclic method of vacuum gas oil refining

In order to increase the yield of light fractions, a method is proposed in which the residue of atmospheric distillation is returned to secondary processing together with the fresh part of gasoil. In the process of processing with each cycle the viscosity of the residue increases about 1.3 times at 80oC. According to GOST the viscosity of M40 fuel oil should not exceed 59 cSt at 80oC. Therefore, after 5 processing cycles the residue is drained and sent for analysis. In case of compliance with GOST requirements it is used as M40 fuel oil.

Block diagram of cyclic method
vacuum gas oil refining

Material balance of cyclic method of vacuum gas oil refining

Feedstock loading is constant 1000 kg/h.
1 cycle Raw material - gas oil -1000 kg.
Output: Fraction n.k.-360оС - 370 kg, gas and losses 30 kg residue - 600 kg.
2 cycle Raw material - gas oil - 400 kg + residue 600 kg.
Output: Fraction n.k.-360оС - 370 kg, gas and losses 30 kg residue - 600 kg.
3 cycle Raw material - gas oil - 400 kg + residue 600 kg.
Output: Fraction n.k.-360оС - 370 kg, gas and losses 30 kg residue - 600 kg.
4 cycle Raw material - gas oil - 400 kg + residue 600 kg.
Output: Fraction n.k.-360оС - 370 kg, gas and losses 30 kg residue - 600 kg.
5 cycle Raw material - gas oil - 400 kg + residue 600 kg.
Output: Fraction n.k.-360оС - 370 kg, gas and losses 30 kg residue - 600 kg.
Total: 2600 kg of gasoil.
Obtained: 1850 kg of fraction n.k.-360оС 71.2%;
150 kg of hydrocarbon gas and losses of 5.8%;
600 kg M40 23%.

Electrodischarge cracking of heavy oil (Usinsk)

Sequence and results of heavy crude oil refining

Distillation of initial heavy oil without ER treatment yielded about 34% of 40-360oC fraction and 66% of high-viscosity residue.
Processing of the residue in the ER reactor at 100oC with obtaining of processed product 58% and hydrocarbon gas about 8% in terms of oil taken.
Atmospheric distillation of the residue after treatment in the ER reactor with obtaining the fraction n.k.-360оС, residue and gas. The yield of distillate was 20%, 38% of thermobitumen in terms of oil taken.
Secondary distillation of total liquid fractions n.k.-360оС was obtained, %: gasoline fraction n.k.-200оС - 28.8; kerosene fraction 201-250оС - 15.4, diesel fraction 251-360оС - 42.3, distillation residue - 13.5.

Cyclic method of heavy oil refining

In order to increase the yield of light fractions, a method similar to the processing of tar sands from the AVT unit is proposed, in which the residue of atmospheric distillation is returned for secondary processing together with the fresh part of heavy oil.
Presumably it will be possible to obtain about 42% of the n.k.-360oC fraction, about 50% of M100 fuel oil and about 8% of hydrocarbon gases.

Experimental production unit
in a container

Technical characteristics
of the experimental production unit