RU2513908C1 - Method of gasoline stabilisation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method of gasoline stabilisation is implemented by unstable gasoline delivery to the feed zone of the stabiliser tower, output of stabilisation fumes from the top of the stabiliser tower and output of liquid from below of the stabiliser tower. Stabilisation is carried out in a vertical fractionating unit with falling-down film and three heat-and-mass exchange sections, one of them is located above the feed zone while the two remaining sections - the medium and the lower one - are located below the feed zone. The upper heat-and-mass exchange section of the fractionating unit is cooled by delivery of the cooling agent to the upper part and outputting it from below part of the heat-and-mass exchange section. The medium and the lower heat-and-mass exchange sections of the fractionating unit are heated up by heat medium delivery to the lower part and outputting it from below of the section and by delivery of stable gasoline from below of the fractionating unit to the lower part and outputting it from the upper part of the medium heat-and-mass exchange section.

EFFECT: simplifying the method, increasing output of the stable products and reducing energy costs.

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Description

The invention relates to methods for stabilizing gasoline fractions and can find application in the oil and gas, oil refining and petrochemical industries to reduce saturated vapor pressure to a standard value.

Known installation of stabilization of hydrocarbon mixtures [RF Patent No. 2194739, IPC C10G 7/02, C10G 49/00, publ. December 20, 2001], in which stabilization is carried out by supplying unstable raw materials to a three-phase separator, withdrawing the separated gas and water for further processing, separating the separated unstable raw materials into two streams, most of which passes through a regenerative heat exchanger, where heat is exchanged with the waste from the column with a stable product, and enters the feed zone located in the middle part of the stabilization column. The rest of the unstable stream is mixed with stabilization vapors discharged from the top of the stabilization column and fed to an air cooler, then to a water cooler, and then to a reflux tank. Stabilization gas, hydrocarbon condensate, which is returned for irrigation to the top of the stabilization column, and water, which is removed for further processing, are removed from the reflux tank. Heat is supplied to the bottom of the stabilization column due to the circulation of the hot stream through the fire heating furnace. A stable product is removed from the bottom of the stabilization column, which is subsequently cooled in a recuperative heat exchanger, air cooler, water cooler and removed from the unit.

However, the method is designed to stabilize the hydrogenate of diesel fuel and cannot be used to stabilize gasoline, since mixing part of the unstable raw materials containing heavy hydrocarbons with stabilization vapors and returning them after condensation to the top of the stabilization column, which leads to a violation of the fractionation mode in the stabilization column and , accordingly, the increase in energy consumption for heating the bottom and cooling the top of the stabilization column in order to increase the steam and reflux numbers to compensate for the fractionation efficiency. In addition, the method is ineffective in stabilizing gasoline due to the high energy consumption for cooling and condensing the mixture of stabilization vapors and part of the unstable product due to the need to maintain a large flow of cooling air due to the low temperature pressure in the air cooler. A disadvantage of the described method is also a decrease in the separation efficiency due to the use of a "hot stream" for heating the bottom of the stabilization column instead of a heating apparatus with a phase interface (riboilera).

Closest to the claimed method according to the technical nature and adopted as a prototype a method of stabilizing coking gasoline [RF Patent No. 2051950, IPC C10G 7/02, C10G 5/04, publ. 01/10/1996] by supplying unstable gasoline to the middle part (feed zone) of the stabilization column, supplying to the bottom of the column vapors obtained by partial evaporation of liquid from the bottom of the stabilization column in the riboiler due to the heat of the cooled heavy gas oil, and output from a stable gasoline riboiler. From the top of the stabilization column output stabilization pairs. Heavy gas oil is removed from the bottom of the distillation column, in which vapors from coking reactors are fractionated and heavy gas oil removed from the bottom of the absorption column, and unstable gasoline is removed from the top of the distillation column. Heavy gas oil after cooling in a riboiler is fed to an absorption column to absorb vapors from the heating, steaming and cooling of coking reactors and the heavy gas oil is removed to a distillation column.

However, the method is characterized by a low yield of stable gasoline due to losses of light components due to the lack of cooling of the upper part of the stabilization column, as well as high energy consumption due to the lack of heat recovery of the heated stable gasoline. In addition, the method is complex and involves the use of a large number of equipment.

The objective of the invention is to simplify the method, increase the yield of a stable product and reduce energy consumption.

The technical result that can be obtained by implementing the method:

- simplification of the method by reducing the number of stages,

- increase the yield of stable gasoline by reducing the loss of light components with stabilization pairs,

- reduction of energy consumption due to heat recovery of heated stable gasoline.

The specified technical result is achieved by the fact that in the known method, which includes supplying unstable gasoline to the feed zone of the stabilization column (fractionation apparatus), the output of stabilization vapors from the top of the stabilization column and the output of liquid from the bottom of the stabilization column

stabilization is carried out in a vertical fractionating apparatus with a falling film and three heat and mass transfer sections, one of which is the upper one located above the power zone, and the other two, the middle and lower ones are located below the power zone,

while the upper heat and mass transfer section of the fractionation apparatus is cooled by supplying refrigerant to the upper part and removing it from the lower part of the upper heat and mass transfer section,

and the middle and lower heat and mass transfer sections of the fractionating apparatus are heated, supplying the coolant to the lower part and removing it from the upper part of the lower heat and mass transfer section, as well as supplying stable gasoline from the bottom of the fractionating apparatus to the lower part and removing it from the upper part of the average heat mass transfer section.

In the inventive method, cooling the upper part of the fractionating apparatus by supplying a refrigerant to the upper heat and mass transfer section reduces the loss of light gasoline fractions due to their condensation, which increases the yield of stable gasoline.

Heating the bottom of the fractionation apparatus by supplying stable gasoline to the middle heat and mass transfer section and supplying a heat carrier to the lower heat and mass transfer section allows the light hydrocarbons of stabilization vapors to be steamed from stable gas without using a riboiler.

The supply of heated stable gasoline taken from the bottom of the fractionating apparatus as a coolant to the bottom of the middle heat-mass transfer section allows to reduce the energy consumption for stabilization by recovering the heat of hot stable gasoline and using it for fractionation.

As heat and mass transfer sections, for example, devices consisting of a liquid distributor and a block of heat and mass transfer elements of a spiral-radial type with vertical mass transfer surfaces are used.

The method is as follows.

Unstable gasoline I is fed into the feed zone 1 of the fractionating apparatus 2, and the coolant II is fed into the lower part and removed from the upper part of the lower heat and mass transfer section 3. Stable gasoline III is supplied as a coolant to the lower part in order to recover heat from the bottom of the fractionating apparatus 2 and withdrawn from the upper part of the middle heat and mass transfer section 4. In order to reduce the loss of gasoline fractions, it is supplied to the upper part of the upper heat and mass transfer section 5, and refrigerant IV is removed from the lower part. From the top of the fractionation apparatus 1 output pairs of stabilization V.

Example 1 (prototype). Unstable gasoline (100% of the mass), containing, wt.%: Ethane 0.22; propane 2.40; butanes 12.40; pentane and higher 84.98, at a temperature of 20 ° C and a pressure of 1.013 MPa gage. injected in liquid form into the feed zone of a plate-shaped stabilization column with a separation capacity of 16 theoretical plates equipped with a riboiler. From the top of the stabilization column at a temperature of 97.9 ° C selected pair of stabilization in the amount of 17.5% of the mass. Stable gasoline with a vapor pressure of 66.7 kPa in the amount of 82.5% of the mass is selected from the riboiler at a temperature of 169.5 ° C.

Heat consumption amounted to 380 MJ / t of product.

Example 2. Unstable gasoline (100% of the mass), containing, wt.%: Ethane 0.22; propane 2.40; butanes 12.40; pentane and higher 84.98, with a temperature of 20 ° C and a pressure of 1.013 MPa gage. they are injected in liquid form into the feeding zone of a plate-shaped stabilization column with dividing ability of the upper and lower parts of the column of 8 theoretical plates, equipped with a riboiler and a system for supplying acute irrigation to the top of the column. Multiplicity of irrigation 1: 1. From the top of the stabilization column at a temperature of 55.6 ° C., stabilization vapors are taken in an amount of 13.1% of the mass. From the bottom of the stabilization column at a temperature of 169.0 ° C, stable gasoline with a vapor pressure of 66.7 kPa in the amount of 86.9% of the mass is selected

Cold consumption amounted to 87 MJ / t of product, heat - 414 MJ / t of product. The total energy consumption amounted to 501 MJ / t.

Example 3. Unstable gasoline (100% of the mass), containing, wt.%: Ethane 0.22; propane 2.40; butanes 12.40; pentane and higher 84.98, with a temperature of 20 ° C and a pressure of 1.013 MPa gage. served in liquid form in the feed zone located in the middle part of the stabilization column, which is a fractionating apparatus with a falling film, with an upper heat and mass transfer section having a separation capacity of 8 theoretical plates, an average heat and mass transfer section having a separation capacity of 2 theoretical plates, and a lower heat and mass transfer section having a separating capacity of 6 theoretical plates. The upper part of the stabilization column is heated by supplying a coolant to the lower part of the lower heat and mass transfer section and supplying stable gasoline with a temperature of 169.1 ° С taken from the bottom of the stabilization column to the lower part of the middle heat and mass transfer section. From the top of the stabilization column at a temperature of 68.7 ° C, stabilization vapors are taken in the amount of 13.2% of the mass, stable gasoline with a vapor pressure of 66.7 kPa the amount of 86.8% of the mass.

The cold consumption was 235 MJ / t of product, the heat consumption was 146 MJ / t of product. The total energy consumption amounted to 381 MJ / t.

A comparison of examples 1 and 3 indicates that the proposed method allows to increase the yield of stable gasoline at close energy consumption, a comparison of examples 2 and 3 shows that with an almost equal output of stable gasoline, the proposed method allows to reduce energy consumption.

The proposed method for stabilizing gasoline can find application in the oil and gas, oil refining and petrochemical industries to reduce saturated vapor pressure to a standard value.

Claims (1)

A method of stabilizing gasoline by supplying unstable gasoline to the stabilization column power supply zone, withdrawing stabilization vapors from the top of the stabilization column and draining liquid from the bottom of the stabilization column, characterized in that stabilization is carried out in a vertical fractionating apparatus with a falling film and three heat and mass transfer sections, one of of which - the upper one is located above the food zone, and the other two - the middle and lower ones are located below the food zone, while the upper heat-mass transfer section of the fractionating ap the coolant is cooled by supplying a refrigerant to the upper part and removing it from the lower part of the upper heat and mass transfer section, in addition, the middle and lower heat and mass transfer sections of the fractionation apparatus are heated, supplying the coolant to the lower part and removing it from the upper part of the lower heat and mass transfer section as well as supplying stable gasoline from the bottom of the fractionating apparatus to the lower part and removing it from the upper part of the middle heat-mass transfer section.

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