RU2393347C1 - Oil treatment method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: oil is separated into fractions in rectification column, volatile compounds are directed to heat exchanger, then they are directed to condensate collector where liquid phase is separated and deposited to the bottom and vapour phase accumulated in upper part is separated. Water with temperature is discharged from the bottom of condensate collector. Above, from the level above water layer there discharged are liquid hydrocarbons C_6+above for further cooling in heat exchangers and accumulation in buffer separation capacity. Some portion of liquid hydrocarbons C_6+above is supplied to consumers, and the rest portion is supplied to oil flow entering the rectification column. Broad fractions of light hydrocarbons (BFLH) are directed from condensate collector to additional heat exchanger where they are cooled up to the temperature enough for condensation. Then condensed BFLH is directed to buffer separation capacity wherefrom BFLH is pumped out and some portion of BFLH is supplied to upper part of rectification column, and excess portion of BFLH is supplied to the store.

EFFECT: increasing the output of broad fraction of light hydrocarbons from oil.

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Description

The invention relates to the oil industry and may find application in the preparation of oil in the oil field and the allocation of a wide fraction of light hydrocarbons (BFLH).

There is a method of oil refining by heating and separation in a fractionating column at a pressure of 0.005-0.25 MPa to obtain stable oil and from the top of the column of low boiling fractions when a portion of the cooled stable oil is fed to the top of the column, followed by compression of low boiling fractions and feeding them to the bottom of an incomplete distillation columns with separation at a pressure of 0.8-1.2 MPa into a residual fraction and a vapor phase discharged from the top of the column, followed by condensation to produce gas and condensate containing NGL. To increase the yield of NGL, gas and condensate are directed by gravity to separation in the middle of the fractionating absorber, the residual fraction is sent to the helmet of the fractionating absorber, the intermediate fraction obtained from the first plate above the feeding zone is mixed with the feedstock, and a wide fraction of light hydrocarbons is removed from the bottom of the fractionating absorber ( RF patent No. 1372922, publ. 2000.02.20).

The known method does not allow to select from oil a significant amount of BFLH.

Closest to the proposed invention in technical essence is a method of stabilizing oil in a complex oil treatment unit (V.P. Tronov. Gas separation and reduction of oil losses. Kazan: Fen, 2002, p. 255-256 - prototype). In the preparation of oil, oil is divided into fractions in a distillation column, volatile compounds are cooled in a heat exchanger, BFLH separation, the return of BFLH to the upper part of the distillation column, and the rest of the unit are sent to the warehouse. An oil separation unit includes pumps, heat exchangers, a desalination-dewatering sump, an oven, a distillation column, water-cooled refrigerators, a separator for a wide fraction of light hydrocarbons, a tank for collecting vapor phase condensate, and an oil separator. A distillation column, a water-cooled refrigerator, a BFLH separator, a pump and pipelines are involved in the cycle of producing BFLH.

The mass fraction of selected BFLH is up to 3.5% of the mass of desalted oil, which is not more than 80% of the potential.

The proposed method solves the problem of increasing the yield of NGL from oil.

The problem is solved in that in a method for preparing oil, comprising separating oil into fractions in a distillation column, cooling volatile compounds in a heat exchanger, separating a wide fraction of light hydrocarbons (BFLH), returning a portion of BFLH to the upper part of the distillation column and directing the rest to a warehouse, according to According to the invention, volatile vapor pairs are cooled in a heat exchanger to a temperature sufficient to condense C _{6 +} hydrocarbons _above and water at a steady pressure in the heat exchanger, and before separation we take CFC-vapor containing C ₂ -C ₅ vapors, condensed components C _{6 + above} and water are sent to the condensate collector, where the liquid phase is separated and precipitated to the bottom of the condensate collector, water is removed from the bottom of the condensate collector for technological purposes, higher from the level above the water a layer of liquid hydrocarbons is withdrawn ₊ C _{6 above} for further cooling in the heat exchangers and storage in the buffer-separation tank, the liquid part of the C _{6 +} hydrocarbons is sent to consumers _above, the remainder is fed to the oil stream entering the recto fikatsionnuyu column and NGL from the condensate is directed to a further heat exchanger where they are cooled to a temperature sufficient to condense the hydrocarbons C ₂ -C _5.

SUMMARY OF THE INVENTION

The problem of increasing the output of BFLH from oil has been solved in many ways, but so far the output of BFLH does not exceed 80% of the possible. The proposed method solves the problem of increasing the yield of NGL from oil. The problem is solved as follows.

When preparing oil, use the equipment shown in figures 1 and 2. According to the technological scheme of oil preparation, oil is separated into fractions in a distillation column 1 at a temperature of 130-150 ° C and a pressure of 4.8-5.3 kgf / cm ² . Volatile compounds with a temperature of 110-120 ° C are taken from the top of column 1, they are sent to heat exchanger 2 under a pressure of 4.8-5.5 kgf / cm ² , where they are cooled to a temperature of 70-90 ° C. From heat exchanger 2, a mixture of NGF vapor with a composition of C ₂ -C ₅ hydrocarbons, condensed components C _{6 + above} and water are sent to a condensate collector 3 at a pressure of 4.8-5.5 kgf / cm ² to separate the gaseous (NGL) and liquid phase ( components C _{6 + above} and water). Condensate collector 3 is a container with a volume of 16 to 100 m ³ , equipped with an internal filling for condensation of water vapor and the C _{6 +} hydrocarbon fraction _above , separate removal of water and condensed C _{6 +} hydrocarbons from the water tank _above and the discharge of NGL.

The flow of the gas-liquid mixture enters the condensate collector 3 under the coalescing section 4, which is a frame structure in which coalescing elements are placed, which are finned tubes with a diameter of 25 mm with a finning coefficient of 9 to 20, the length of the tubes is 2-3 m, the package consists of 8- 12 rows of 30-60 pipes in a row. In the coalescing section 4, small droplets of the liquid phase are discharged, coarsened and deposited on the bottom of the condensate collector 3. At the bottom, the liquid consisting of water and components C _{6 + above} is separated by the difference in densities into water and components C _{6 + above} . From the bottom of the condensate collector 3, water is discharged at a temperature of 70-90 ° C with a flow rate of 3-12 m ³ / h and under a pressure of 4.5-5.2 kgf / cm ² for reuse for technological purposes (for desalting oil and increasing production of BFLH ) Components C _{6 + above} are removed from the level above the water layer with a flow rate of 2-10 m ³ / h and at a pressure of 4.5-5.2 kgf / cm ² (depending on the required composition of the mixture of components C _{6 + above} ) for further cooling in heat exchangers 5 and accumulations in buffer-separation tanks 6. A part of the liquid C _{6 +} hydrocarbons _{above is} sent to consumers, the rest is fed into the oil stream entering the distillation column 1.

In the condensate collector, 3 pairs of BFLH after separation of the liquid phase are directed to the drop collector 7, which is a coalescing nozzle on the perforated pipe, where drops of hydrocarbons C _{6 + above} are separated and then to the outlet of the condensate collector 3 for subsequent cooling and condensation in heat exchangers 8, where the BFLH is cooled to temperature (10-22 ° C), sufficient for condensation of hydrocarbons composition C ₂ -C ₅ at a pressure of 4-4.5 kgf / cm ² . Next, the condensed BFLH is sent to a buffer-separation tank 9 with a flow rate of 20-30 m ³ / h and at a pressure of 4-4.8 kgf / cm ² , where non-condensed hydrocarbons and water residues are separated. From the buffer-separation tank 9, BFLH with a flow rate of 20-30 m ³ / hour by gravity or pump 10 is pumped into the gas storage 11.

Concrete example

Spend the separation of oil into fractions in the distillation column 1 (see figure 1 and 2) with a flow rate of desalted oil at the inlet of 380 t / h at a temperature of 140 ° C and a pressure of 5.1 kgf / cm ² . Volatile compounds with a temperature of 116 ° C are taken from the top of column 1, sent to heat exchanger 2, where they are cooled to a temperature of 85 ° C. A gas-liquid mixture of hydrocarbons is sent to the condensate collector 3. From the bottom of the condensate collector 3, water with a temperature of 85 ° C is discharged in a volume of 5.6 m ³ / h for reuse for technological purposes. Above the level above the water layer, liquid C _{6 +} hydrocarbons are removed in a volume of 14 m ³ / h for further cooling in heat exchangers 5 and accumulated in buffer and separation tanks 6. 30% of the C _{6 + higher} hydrocarbons are sent to consumers, the rest is supplied to the flow of oil entering the distillation column 1. The vapor of BFLH from the condensate collector 3 is sent to additional heat exchangers 8, where they are cooled to a temperature of 15 ° C, sufficient for condensation at a pressure of 4.3 kgf / cm ² . Next, the condensed BFLH is sent to the buffer separation tank 9, from which the BFLH is pumped out by a pump 10 in a volume of 30 m ³ / h to the gas storage 11.

The proposed method in comparison with the traditional allows you to increase the selection of NGL from oil to 95% of the potential, which is 15% more than the prototype.

The application of the proposed method will solve the problem of increasing the yield of BFLH from oil.

Claims (1)

The method of oil preparation, including the separation of oil into fractions in a distillation column, cooling the volatile compounds in a heat exchanger, separating a wide fraction of light hydrocarbons — BFLH, returning a part of BFLH to the upper part of the distillation column and directing the rest to a warehouse, characterized in that the vapor of volatile compounds is cooled in the heat exchanger to a temperature sufficient to condense C _{6 +} hydrocarbons _above and water at a steady pressure in the heat exchanger, and before separating the BFLH pair with the composition C ₂ -C ₅ , the condensed components C _{6 + above} and water are sent to the condensate collector, where the liquid phase is separated and precipitated to the bottom of the condensate collector, water is removed from the bottom of the condensate collector for technological reuse, above the level above the water layer are liquid C _{6 +} hydrocarbons _higher for further cooling in the heat exchangers and storage in the buffer-separation tank, the liquid part of the C _{6 +} hydrocarbons is sent to consumers _above, the remainder is fed to the flow of oil entering the distillation column and SHFL of condensate is sent to a further heat exchanger where they are cooled to a temperature sufficient to condense the hydrocarbons C ₂ -C _5.

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