RU2553734C1 - Oil treatment method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: oil treatment method includes oil separation into fractions in the rectification tower, extraction of natural gas liquids (NGL), cooling of NGL up to temperature sufficient for condensation, delivery of condensed NGL to buffer-separating container, pumping out of a part of NGL to the top part of the rectification tower and excessive part to the warehouse. NGL vapours are taken from the top of the rectification tower, NGL vapours are cooled down in heat exchanger until liquid-gas mixture is formed, then the liquid-gas mixture is cooled in the other heat exchanger, further the liquid-gas mixture is cooled down in air cooler until NGL are transferred to liquid state, thereafter NGL are subject to separation in reflux tank and in centrifugal vertical gas separator, wherein from NGL water and light hydrocarbon gases are separated.

EFFECT: increased output of NGL due to reduced losses at pre-treatment.

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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 with the release 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 the low boiling fractions and their downward flow of an incomplete distillation column with separation at a pressure of 0.8-1.2 MPa into the residual fraction and the vapor phase discharged from the top of the column, followed by its 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 supply 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 provide for the recovery of thermal energy of condensed products in order to heat process fluids in the form of oil and those. fresh water and does not allow the selection of oil from the potential amount of NGL.

There is a method of stabilizing oil at the complex oil treatment unit (VP Tronov. Gas separation and reduction of oil losses. Kazan: Fen, 2002, pp. 253-256 - prototype). In the preparation of oil, oil is separated 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 vapor phase condensate collecting tank, and an oil separator. A distillation column, a water-cooled refrigerator, a BFFL 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 disadvantage of this method is not a high yield of BFLH from oil.

Closest to the proposed invention in technical essence is a method of oil preparation, including the separation of oil into fractions in a distillation column, cooling volatile compounds in a heat exchanger, separating a wide fraction of light hydrocarbons (BFLH), returning a part of BFLH to the top of the distillation column and directing the rest to the warehouse, according to the invention, the pairs of volatile compounds are cooled in a heat exchanger to a temperature sufficient to condense C _{6 +} hydrocarbons _above and water when installed pressure in the heat exchanger, and before separation of the BFLH vapor 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 reuse in technological For purposes above, liquid C _{6 +} hydrocarbons are removed from a level above the water layer for further cooling in heat exchangers and accumulated in a buffer-separation tank, a portion of liquid C _{6 +} hydrocarbons _{above is} sent to consumers, the rest The bulk part is fed into the oil flow entering the distillation column, and the NGL from the condensate collector is sent to an additional heat exchanger, where they are cooled to a temperature sufficient to condense C ₂ -C ₅ hydrocarbons. (Patent 2393347, CL ЕВВ 43/34, publ. 06/27/2010).

The disadvantage of this method is the one-stage cooling of BFLH, which leads to an incomplete transition of BFLH vapor to a liquid state and the loss of a part of BFLH during further preparation.

The proposed invention solves the problem of increasing the yield of NGL by reducing losses in preparation.

The problem is solved in that in the method of oil preparation, including the separation of oil into fractions in the distillation column, the allocation of BFLH, cooling BFLH to a temperature sufficient for condensation, the direction of the condensed BFLH to the buffer separation tank, pumping part of BFLH to the top of the distillation column and excess parts to the warehouse, according to the invention, the vapor of BFLH is removed from the top of the distillation column, the vapor of BFLH in the heat exchanger is cooled to form a gas-liquid mixture, then it is cooled in another heat exchange The gas-liquid mixture is then cooled, then the gas-liquid mixture is cooled in an air-cooling apparatus until the BFLH becomes liquid, after which the BFLF is separated in a reflux tank and in a centrifugal vertical gas separator, where water and light hydrocarbon gases are separated from the BFLH.

SUMMARY OF THE INVENTION

In known methods for producing BFLH, volatile compounds from the top of a distillation column with a temperature of 110-120 ° C are sent to a heat exchanger, cooled, sent to a condensate collector, separated into fractions, and BFLH pairs from a condensate collector are sent to additional heat exchangers, where they are cooled to a temperature sufficient for condensation . Next, the condensed BFLH is sent to a buffer separation tank, from which the BFLH is pumped to a gas depot with a pump. The selection of BFLH takes place in a condensate collector, and cooling to a liquid state is carried out in one cycle in one heat exchanger. With this cooling, some of the NGL vapor does not have time to become liquid and is inevitably lost in the buffer-separation tank and pipelines. The proposed invention solves the problem of increasing the yield of NGL by increasing the degree of condensation of hydrocarbons from NGL vapor. The problem is solved by means of the oil treatment unit shown in FIG. one.

- нефть,

- ШФЛУ,

- дистиллят,

- несконденсировавшиеся углеводороды.In FIG. 1 the following designations are adopted: 1 - crude oil metering unit, 2 - crude oil-stable oil heat exchanger, 3 - crude oil-BFLH heat exchanger, 4 - oil dehydration-desalination unit, 5 - dehydrated and desalted oil pump, 6 - heat exchanger "dehydrated and desalted oil - stable oil", 7 - oil heating furnace, 8 - distillation column for oil stabilization, 9 - heat recovery heat exchanger vapor of oil distillate, 10 - fresh water heat exchanger - ShFLU, 11 - ShFLU air cooling apparatus 12 - metering station for stable oil, 13 - reflux capacity, 14 - ShFLU transfer pump, 15 - ShFLU storage warehouse, 16 - distillate separation and storage unit, 17 - fresh water transfer pump, 18 - centrifugal vertical gas separator, ……… - fresh process water,

- oil

- NGL,

- distillate,

- non-condensing hydrocarbons.

Installation of oil preparation works as follows.

Crude oil is supplied to the oil metering unit 1 and then to the “crude oil - stable oil” 2 heat exchanger, in which it is heated by heat exchange with stable oil. Next, crude oil enters the heat exchanger "crude oil - BFLH" 3, where due to heat exchange with BFLH coming from the distillation column stabilization of oil 8, is heated, and BFLH is cooled. Then the crude oil enters the oil dehydration-desalination unit 4, then is pumped by pump 5 to the desalted oil-stable oil heat exchanger 6, where it is heated, then to the oil heating furnace 7, where it is additionally heated and then fed to the oil stabilization rectification column 8. In the column, crude oil is divided into fractions, resulting in the formation of stable oil. Then the stable oil is sequentially cooled in heat exchangers 6 and after accounting at the oil metering unit 12, it enters the fleet.

BFLH enters from the top of distillation column 8 into the heat exchanger 3, is cooled to form a gas-liquid mixture and goes for further cooling to the fresh water-BFLH heat exchanger 10, where the BFLH gas-liquid mixture is cooled by heating fresh water coming from the centralized water supply system. Next, BFLH enters the air-cooling apparatus 11 equipped with a system for automatically controlling the fan speed for after-cooling to a temperature not exceeding 30 ° С, i.e. before the transition of BFLH to a liquid state. Then NGL is subjected to separation with separation of water in the reflux tank 13, and in a centrifugal vertical gas separator 18, where light hydrocarbon gases are separated from the NGL. Thus prepared BFLH by the transfer pump of BFLU 14 is sent to the storage location of BFLH 15.

From the distillation column 8, distillate enters the heat exchanger 9. Fresh water heated in the heat exchanger 10 is pumped by the pump 17 and enters the heat exchanger 9, where it is heated by heat exchange with distillate vapor. The distillate, cooled to a condensation temperature of hydrocarbon components C _{5 + above} , comprising 45-50 ° C, enters the separation and storage unit 16.

Concrete example

Crude oil with a flow rate of Q = 400-700 m ³ / h, temperature T = 6-25 ° C, density 855-865 kg / m ³ , water cut from 0.5 to 5% comes from the tank farm to the oil control and treatment unit (Fig. 1), where after accounting at the metering unit, oil 1 enters the heat exchanger “crude oil - stable oil” 2, in which it is heated to a temperature of 35-60 ° C due to heat exchange with stable oil. Then the crude oil enters the heat exchanger “crude oil - BFLH” 3, where due to heat exchange with BFLH with a flow rate of Q = 15-20 t / h, temperature T = 80-110 ° C, coming from the distillation column of oil stabilization 8, is heated to 6-10 ° C, and NGL is cooled to a temperature of 50-70 ° C. Then the crude oil enters the oil dehydration-desalination unit 4, then is pumped by pump 5 to the desalted oil-stable oil heat exchanger 6, where it is heated to 100-130 ° C, then to the oil heating furnace 7, where it is heated to a temperature of 130-180 ° С, then oil enters the distillation column of oil stabilization 8. Then stable oil is sequentially fed to heat exchangers 6 and 2, cooled by heat exchange with crude oil to a temperature of 25-35 ° С, then after accounting at the metering station, oil 12 enters the commodity the park.

Cooled to 50-70 ° C, BFLH after heat exchanger 3 is fed for further cooling to the "fresh water - BFLH" 10 heat exchanger, where it is cooled to a temperature of 15-45 ° C, heating fresh water coming from the centralized water supply system to a temperature of 15-40 ° C. Next, BFLH enters the air-cooling apparatus 11, equipped with a system for automatically controlling the speed of rotation of the fan for after-cooling to a temperature not exceeding 30 ° C. Then NGL is subjected to separation with separation of water in the reflux tank 13, and in a centrifugal vertical gas separator 18, where light hydrocarbon gases are separated from the NGL. Thus prepared BFLH by the transfer pump of BFLU 14 is sent to the storage location of BFLH 15.

Fresh water heated in the heat exchanger 10 enters the heat exchanger 9, where due to heat exchange with vapors of the distillate having a flow rate of Q = 2 t / h and a temperature of T = 120 ° C, it is heated to a temperature of 30-60 ° C. The distillate, cooled to a condensation temperature of hydrocarbon components C _{5 + above} , comprising 45-50 ° C, enters the separation and storage unit 16.

As a result, it is possible to increase the yield of NGL by 5% and bring it to 99% of the potential.

The application of the proposed method will allow to solve the problem of increasing the yield of BFLH by reducing losses during preparation.

Claims (1)

A method for preparing oil, including dividing the oil into fractions in a distillation column, isolating a wide fraction of light hydrocarbons, cooling a wide fraction of light hydrocarbons to a temperature sufficient for condensation, directing the condensed wide fraction of light hydrocarbons to a buffer separation tank, pumping part of a wide fraction of light hydrocarbons into the upper part of the distillation column and the excess part to the warehouse, characterized in that the vapors of a wide fraction of light hydrocarbons are taken from the top and distillation columns, cool the vapors of a wide fraction of light hydrocarbons in a heat exchanger to form a gas-liquid mixture, then cool the gas-liquid mixture in another heat exchanger, then cool the gas-liquid mixture in an air-cooling apparatus until a wide fraction of light hydrocarbons becomes liquid, and then expose a wide fraction of light hydrocarbons separation in a reflux tank and in a centrifugal vertical gas separator, where water and water are separated from a wide fraction of light hydrocarbons Soft hydrocarbon gases.

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