WO2024019638A1

WO2024019638A1 - Method for vacuum distilling hydrocarbon residues and heavy fractions

Info

Publication number: WO2024019638A1
Application number: PCT/RU2023/050078
Authority: WO
Inventors: Александр Владимирович ЗУЙКОВ
Original assignee: Александр Владимирович ЗУЙКОВ
Priority date: 2022-07-16
Filing date: 2023-04-08
Publication date: 2024-01-25

Abstract

The invention relates to a method for vacuum distilling hydrocarbon residues and heavy fractions which includes supplying a feedstock to a furnace and passing the flow heated in the furnace into the lower part of a main vacuum distillation column, with an additional vacuum distillation column being situated below the main part of the vacuum column. The method includes installing between the lower part of the main vacuum distillation column and the upper part of the additional vacuum distillation column a chimney tray, wherein egress of a vapour phase is provided from the upper part of the additional vacuum distillation column to a unit of a vacuum generating system. The technical result lies in more energy efficient operation, increased separation of gasoil cuts, and reduced greenhouse gas emissions during operation.

Description

METHOD FOR VACUUM DISTILLATION OF HYDROCARBON RESIDUE AND HEAVY FRACTIONS

The invention relates to the oil and petrochemical industry, in particular, to columns for the vacuum distillation of hydrocarbon residues and heavy fractions and can be used to increase the energy efficiency of process units, increase the selection of products and reduce greenhouse gas emissions, including a vacuum unit.

Known is “METHOD FOR VACUUM DISTILLATION OF LIQUID PRODUCT AND INSTALLATION FOR ITS IMPLEMENTATION” RU 2083638[1], which includes feeding a liquid product into a vacuum column, removing the liquid fraction from it, feeding the liquid fraction after cooling into the column as circulation irrigation and pumping out of the column with a jet apparatus vapor-gas phase, the liquid fraction of the vacuum column is fed into the jet apparatus as the active medium, the cooling and compression of the vapor-gas phase is carried out in the flow part of the jet apparatus by mixing the vapor-gas phase with the liquid fraction, converting its condensing components into a liquid state, the resulting gas-liquid mixture is fed from the jet apparatus into the separator, from where, after separation into gaseous and liquid phases, the latter is fed as circulation reflux into a vacuum column.

The disadvantage of this known method is low efficiency, low product selection and increased greenhouse gas emissions.

The closest to the claimed technical solution is “METHOD FOR VACUUM DISTILLATION OF A FLOW OF CRUDE HYDROCARBONS” RU 2621042 [2], which includes feeding raw materials into a furnace, passing the flow heated in the furnace into the lower part of the main vacuum distillation column, below the main part of the vacuum column there is an additional vacuum distillation column .

The known method allows for a slight increase in efficiency due to the presence of an additional distillation column.

The disadvantages of the method include low efficiency due to the ingress of vapor from the additional vacuum column into the main one, increased heat consumption, and the lack of removal of additional product flow and technical condensate.

Technical challenge

The technical problem solved by the proposed method of vacuum distillation of hydrocarbon residues is to increase the efficiency of the vacuum column by reducing the pressure in the stripping zone, located below the zone where raw materials are introduced into the column.

The solution of the problem

The technical result obtained by solving the stated technical problem is to increase the energy efficiency of work (reducing the amount of heat input) and the extraction of gas oil fractions by reducing the pressure in the tar stripping zone, as well as reducing greenhouse gas emissions during the operation of the facility.

The technical result is achieved in that: a method for vacuum distillation of hydrocarbon residues and heavy fractions, including feeding raw materials into a furnace, passing a flow heated in the furnace into the lower part of the main vacuum distillation column, an additional vacuum distillation column is located below the main part of the vacuum column, characterized by the fact that includes a semi-blind plate installed between the lower part of the main vacuum column and the upper part of the additional vacuum column; from the upper part of the additional vacuum column (under the semi-blind plate) the vapor phase exits to the vacuum-creating system block.

The exit of the vapor phase to the block of the vacuum-creating system can be carried out with preliminary condensation and separation into gas, gas oil and condensate.

The vapor phase from the bottom of the column can be transported through a vacuum-creating system (VSS) unit to the area where raw materials are introduced into the column.

Positive effects from the invention

Technical result: Creating a reduced pressure by installing a vacuum-creating system unit on the vapor flow leaving the tar stripping zone allows one to reduce the temperature in the raw material input zone, while increasing the total selection of the distillate fraction by reducing the pressure in the tar stripping zone. In turn, lowering the temperature in the raw material input zone allows the rectification process to be carried out at a lower degree of heating of the raw material of the vacuum column and contributes to the formation of a smaller amount of decomposition gases, which helps to reduce the total pressure in the column and reduce energy costs for VSS. Reducing the degree of heating of the vacuum column feedstock also reduces greenhouse gas emissions from fuel combustion. Also, a decrease in pressure in tar stripping leads to a general decrease in pressure in the column, which makes it possible to reduce the consumption of the working agent in the vacuum-creating system.

Implementation of the invention: On shows the implementation of the method (first option), on shows the implementation of the method (second option), where:

1 – supply of raw materials;

2 – supply of water steam;

3 – oven;

4 – main vacuum column;

5 – additional vacuum column;

6 – vacuum-creating system (VSS) block;

7 – semi-blind plate;

8 – ejecting agent;

9 – gas outlet;

10 – first heat exchanger;

11 – second heat exchanger;

12 – third heat exchanger

13 – yield of tar or heavy residue;

14 – yield of gas oil fraction No. 1;

15 – yield of gas oil fraction No. 2;

16 – condensate outlet;

17 – gas outlet to the VSS;

18 – yield of condensed diesel fraction;

19 – cold flow.

20 – zone for introducing raw materials into the column.

Figure.1

Figure.2

Examples

The method is carried out as follows:

The raw material of the process, the remainder of the atmospheric distillation of oil and/or hydrocarbon raw materials, is sent in direction 1 to the evaporation furnace 3, in which the required level of heating and evaporation of the raw material is ensured and then through a transfer pipeline is supplied to two entry points into the vacuum distillation column 4, into the raw material input zone to column 20.

In the raw material input zone in the column, the flow is divided into two phases - a vapor phase and a liquid phase. The vapor phase is directed to the top of the vacuum distillation column, passes through layers of special packings and internal contact devices.

Part of the vapor that does not condense under the conditions of the given temperature regime of the vacuum distillation column is removed from the top of the column into a special vacuum-creating system 6. The removal of gases 9 from the column through the VSS is ensured by the supply of an ejecting agent (gas and/or liquid flow and/or energy flow and /or mechanical energy, which are used to remove the vapor phase from a low-pressure area to a high-pressure area).

As an ejecting agent 8, depending on the type of vacuum-creating system (VSS), energy/material flows are most often used, which may include water vapor, a component of straight-run or vacuum diesel fuel. In the first embodiment, the ejecting agent is the first heat exchanger 10 with a supply of cold flow 19. By heat exchanger we mean a heat exchange unit, i.e. a set of several heat exchangers and auxiliary technical/technological equipment, for example pumps, separators, etc. Thus, the required and specified value of the residual pressure at the top of the column is maintained. The pressure in the area of input of raw materials and separation into vapor and liquid phases will be greater by the value of the pressure drop when the vapor phase passes through layers of special nozzles and internal contact devices. The pressure in the lower part of the column, which is located below the zone of input of raw materials and separation into vapor and liquid phases, will also be greater than in the zone of input of raw materials and separation into vapor and liquid phases by the value of the pressure drop when the flow of vapor and water vapor passes through layers of special packings and internal contact devices at the bottom of the column.

Part of the vapor phase separated from the raw material in the area of input of raw materials and separation into vapor and liquid phases is condensed at the top of the column using a circulating flow of the liquid phase (called circulation reflux), in the diagram this is the flow taken from the top of the column and passing through the first heat exchanger 10. The heat in which is removed to the cold stream 19. The cooled circulating stream from the first heat exchanger is returned back to the top of the column to condense part of the vapor stream. The resulting balance amount of the liquid phase from the vapor stream is removed from the top of the column in the form of a liquid product stream - condensed diesel fraction (CDF) 18.

In a similar way, condensation of part of the vapor occurs in the middle zone of the vacuum distillation column, where part of the vapor is in contact with the circulating flow (circulation irrigation), cooled in the second heat exchanger 11. The condensed part of the vapor passes into the liquid phase and the balance amount is removed in the form of a second product - the gas oil fraction No. 1 – pos. 14.

Water vapor supplied to the lower part of the vacuum distillation column provides additional evaporation of the target components from the tar. In this case, plate No. #n, located below the raw material input zone, is “semi-blind”, which means that it passes the liquid phase into the lower part of the column into contact with water vapor for additional evaporation. The passage of the liquid phase through the “semi-blind” plate is possible due to the height of the liquid column. In this case, the “semi-blind” plate does not allow vapors to pass from the bottom of the vacuum distillation column into the area where raw materials are introduced into the column. All vapors accumulated under the “semi-blind” plate are sent to the third heat exchanger - (condenser) 12.

The required temperature regime in 12 is ensured by supplying cold flow 19. When the required temperature is achieved, a corresponding condensation of part of the vapor occurs, with the formation of a product, gas oil fraction No. 2 - pos. 15, and also water vapor is condensed and removed in the form of a condensate stream 16. The non-condensed part of the gases is sent to the VSS and then removed from the system 17.

The lower part of the column under the semi-blind plate is designated as an additional vacuum column 5, into which water vapor 2 is supplied, the remaining gas oil components evaporate from the tar, and tar 13 is removed from the lower part.

The pressure in 12 and in the upper part of the additional vacuum column 5 is significantly lower than the pressure in the raw material input zone, which makes it possible to additionally evaporate part of the liquid phase and obtain an additional amount of products expressed in the production of gas oil fraction No. 2.

An option is possible when the vapor phase from the top of the additional column is transported through the VSS to the raw material input zone, shown in .

In combination with the production of an additional amount of products - gas oil fraction No. 2, the presented scheme makes it possible to reduce the temperature of the raw material flow at the outlet of the furnace and, accordingly, the temperature of the raw materials in the zone of raw material input and separation into vapor and liquid phases. A decrease in temperature leads to a decrease in energy consumption in the furnace for the evaporation of raw materials, reduces the amount of gases formed due to decomposition and helps to reduce the overall pressure in the column. The increased consumption of the liquid phase is compensated by an increase in extraction due to a decrease in pressure in the lower part of the column due to the removal of vapors under a “semi-blind” plate into the third heat exchanger and further to the VSS.

The implementation of this method of vacuum distillation of hydrocarbon residues leads to a reduction in energy consumption by 25-30% while simultaneously increasing the extraction and quality of the resulting product. Equivalent to a 25-30% reduction in greenhouse gas emissions from fuel combustion.