CN116064070A - Crude oil bi-component pre-separation method and device - Google Patents

Abstract

The invention belongs to the field of petroleum processing, in particular to the technical field of crude oil distillation, and provides a crude oil bi-component pre-separation method. The non-side line extraction system provided by the invention is free of a tower top condensation separation system, and the non-side line rectifying tower can be a pressurized flash evaporation device for separating crude oil into light fraction and heavy fraction; the fractionation accuracy of two components of crude oil can be achieved by using a small number of matched facilities; the pressure flash evaporation mode is adopted to separate two components of the crude oil which is a wide boiling range medium and is communicated with the pressure of a downstream device system.

Description

Crude oil bi-component pre-separation method and device

Technical Field

The invention belongs to the field of petroleum processing, in particular to the technical field of crude oil distillation. In particular to a crude oil bi-component pre-separation method and a device.

Background

Existing crude oil fractionation methods include flash distillation, atmospheric distillation, and vacuum distillation;

flash evaporation of crude oil: the flash evaporation of crude oil is realized under normal pressure, and the flash evaporation is mainly used for removing gas components and light naphtha components in the crude oil as normal pressure pre-separation means, so that the heating furnace and the conveying conditions are improved, and the components are more overlapped; the low boiling point component which is flashed off is generally sent to an atmospheric tower for continuous treatment;

crude oil atmospheric distillation: is a necessary process for all crude oil distillation. The normal pressure distillation generally adopts the method that oil products cooled by a heat exchange system by extracting liquid from a plurality of sections in a distillation tower are returned to the distillation tower upwards, and crude oil is fractionated according to the true boiling point or boiling range by adopting a step-by-step heat extraction and reflux method; therefore, a heat exchanger, a reflux pump, a liquid collector in the tower and the like are required to be matched for facilitating side extraction; the atmospheric distillation tower is also provided with a tower top product condensing section, the gas product of the rectifying section is condensed into a liquid phase by using cooling water and an air cooler and then is subjected to oil-water separation, and steam with great condensation latent heat is also condensed together, so that the load of the tower top condenser is high; the investment of the normal pressure distillation side line cold exchange system is far higher than that of the fractionating tower; besides, equipment such as a tower top condenser, an oil-water separation tank, a pump and the like is arranged, equipment investment is large, separated water is oily sewage and needs to be purified by a sewage treatment device, and sewage treatment cost is increased;

crude oil reduced pressure distillation: besides the technical characteristics of normal pressure distillation, the crude oil reduced pressure distillation realizes component separation by vacuumizing or negative pressure.

The partial vaporization separation is realized under low pressure in both atmospheric distillation and vacuum distillation, so that the mixed gas and the bottom liquid phase rising in the rectifying section cannot be directly used as raw materials of a downstream device and cannot be directly connected with a catalytic cracking device for transportation. Conventional "flash" techniques after pressurization of crude oil cannot achieve the desired separation of crude oil, such as failing to separate the diesel components, and the separation product components overlap severely, affecting the selectivity of the subsequent reaction.

Disclosure of Invention

Petrochemical industry is large chemical industry, the profit margin according to the output value is low, and the reduction of the investment of the device and the energy consumption of operation are important; the invention aims to provide a crude oil bi-component pre-separation method which does not depend on side line heat exchange, can adjust the separation proportion and the separation precision according to the requirement in operation, can realize pressurized separation according to a downstream device, and has the advantages of low investment and low energy consumption so as to pre-separate the crude oil into two components. The invention also provides a device for realizing the method.

The invention relates to a crude oil bi-component pre-separation method, which is characterized by comprising the following steps of:

the desalted and dehydrated crude oil enters a pressurizing separation tower after being preheated in a heating furnace or heat exchange equipment, and low-boiling-point components are gasified and separated into gas-phase components and high-boiling-point liquid-phase components, and the specific process is as follows:

(1) Pressurizing and preheating the desalted and dehydrated crude oil to form a crude oil stream entering a tower, entering a separation tower, reducing the pressure in the separation tower, gasifying low-boiling components in the crude oil in the separation tower, enabling the gasified gas stream to flow upwards, and settling unvaporized high-boiling components to the bottom of the separation tower;

(2) A cold reflux stream is fed into the upper part of the separation tower, and the cold reflux stream is a liquid stream with the temperature not more than 250 ℃;

the cold reflux stream is a cooled stream of a portion of crude oil, water or a separated bottom liquid component; preferably splitting a portion of the crude oil prior to heating as a cold reflux stream into a separation column from the top; alternatively, a portion of the high boiling point component from the bottom of the column is cooled and then enters the separation column from the top zone as a cold reflux stream; or/and, using water as a cold reflux stream into the separation column from the top;

the cold reflux stream is mixed with the gasified ascending gas stream in the crude oil stream in the separation tower in the top area of the separation tower and cooled, so that the high-boiling point component in the gasified gas stream in the crude oil stream in the tower is liquefied again, the liquefied part flows downwards together with the high-boiling point component in the cold reflux stream, the liquefied part is continuously mixed with the ascending gas below to reduce the content of the high-boiling point component in the gas component, the liquid part returns to the high-boiling point component at the bottom of the separation tower, the low-boiling point gas phase component at the top of the separation tower, namely the tower top component, flows out of the separation tower, and the high-boiling point liquid phase component, namely the tower bottom component, flows out of the bottom of the separation tower;

the temperature of the crude oil stream entering the column or the operating pressure of the separation column or the flow rate of the cold reflux stream are changed, and the composition and flow rate ratio of the separated top component and bottom component are controlled. The separation proportion and the composition or the separation precision are controlled by adjusting the operation pressure of the separation tower and the flow of the cold reflux stream preferentially; in practice, the cold reflux stream is split into several separate streams that enter the separation column at different elevations.

The crude oil bi-component pre-separation method further comprises the step of injecting steam or water before or after the crude oil is heated and enters the separation tower, or injecting steam or water into the liquid phase component at the lower part in the separation tower. So as to reduce the partial pressure of oil gas in the separation tower and gasify the low boiling point component in the liquid phase at the bottom of the tower into gas phase, thereby improving the fractionation accuracy of the two components separated by the separation tower, namely improving the quality of the product. The injection of water or stripping steam is no greater than 15% of the crude oil (mass ratio).

In the invention, crude oil, water and steam entering the separation tower are dispersed to the cross section of the separation tower through a distributor; dispensers are well known to the skilled person.

In the crude oil bi-component pre-separation method, further, water is used as a cold reflux stream of the separation tower, the cold reflux stream enters the separation tower from the top area or/and the middle part of the separation tower, is mixed with the gasified ascending gas in the crude oil stream entering the tower, and is cooled, so that the high-boiling-point components in the gasified components are liquefied. The cold reflux water flow is not more than 10% of the crude oil (mass ratio), and the water is used for stripping sewage by using a catalytic cracking device preferentially.

The crude oil bi-component pre-separation method is characterized in that when the crude oil enters a separation tower, the crude oil is preheated to 200 ℃ to 380 ℃ and the pressure is 250Kpa (absolute) to 1.3Mpa (absolute); the pressure at the top of the separation tower ranges from 230Kpa (absolute) to 460Kpa (absolute).

The invention also provides a crude oil bi-component pre-separation device which is provided with crude oil heat exchange or heating equipment and a separation tower; the separation tower is vertical, the bottom is provided with a tower bottom component liquid outlet, the top is provided with a tower top component gas outlet, the lower part of the outer side is provided with a tower inlet crude oil stream inlet, a steam or water inlet is arranged below the tower inlet crude oil stream inlet, and the top or/and the middle is provided with a cold reflux stream inlet;

a pipeline is connected between the inlet of the crude oil flow entering the tower and the heat exchange or heating equipment or the separation tower;

the cold reflux stream inlet is communicated with an upstream pipeline of the heat exchange or heating equipment, so that crude oil enters the top of the separation tower from the cold reflux stream inlet before being subjected to heat exchange or heating; a pressure regulating valve is arranged on a gas phase pipeline of the tower top component of the fractionating tower to control the operating pressure of the tower top of the separating tower.

The crude oil bi-component pre-separation device is further provided with a water inlet at the middle part and/or the upper part of the separation tower so as to introduce cold reflux water.

The crude oil two-component pre-separation device is further provided with a tray or packing 30 below the cold reflux stream inlet in the separation tower.

The above crude oil two-component pre-separation device, further, a filler or a tray or a liquid coalescing device is arranged below the top outlet of the separation tower or above the inlet of the cold reflux stream, and the coalescing device or the coalescer is well known and can be in a thread shape, a corrugated plate shape and the like.

The invention relates to a crude oil bi-component pre-separation method, which comprises the following steps of:

1. the crude oil bi-component pre-separation comprises a crude oil feeding part, a crude oil separation tower and a product separation control part;

the crude oil is usually pressurized crude oil from a desalting and dewatering device (or crude oil from a storage tank is pressurized by a pump);

the crude oil feeding part comprises a crude oil heat exchange or heating system, a pump, a feeding flowmeter and the like before separation; the product separation control part comprises a tower top reflux control part, a water injection or steam control part and a separation tower top pressure control part;

in the concrete implementation, the crude oil feed is communicated with heat exchange or heating equipment such as a heating furnace or a heat exchanger through a pipeline, the heating furnace or the heat exchanger is communicated with a crude oil feed inlet of a separation tower through a pipeline, a control system consisting of a feed flowmeter and a regulating valve is arranged on the pipeline in front of the heating furnace or the heat exchanger, and a temperature transmitter is arranged on the pipeline between the heating furnace and the separation tower; the pipeline is arranged between the cold reflux material flow and the cold reflux material flow inlet, and when the cold reflux material flow is crude oil, the cold reflux crude oil quantity control system is arranged on the pipeline; the cold reflux flow and the crude oil feeding temperature can be adjusted, so that the separation quality of the two-component separation product is adjusted.

2. When the top cold reflux stream is a part of desalted and dehydrated crude oil, the crude oil is divided into two paths, one path is heated to become a raw material of a feeding part of the separating tower, namely a crude oil stream entering the tower, and the other path is taken as the top cold reflux stream, and the composition of the top cold reflux stream is the same as that of the crude oil of the feeding part; the cold reflux crude oil quantity is not more than 15 percent (mass ratio) of crude oil;

when the cold reflux stream is a part of crude oil and water, the crude oil and the water are preferentially separated into a separation tower, the crude oil is preferentially introduced from the lower part, and the water is introduced from the upper part; preferentially water enters the separation column above the column top zone or tray or packing;

the flow rate of the top reflux crude oil is regulated according to the quality requirements of the downstream device on the top light oil product and the bottom heavy oil product.

3. Steam or stripping steam enters the separation tower through a pipeline or enters the separation tower after being heated by crude oil, is mixed with the crude oil and enters the separation tower, the stripping steam pipeline is provided with a loop control system consisting of a flowmeter and a regulating valve, and the flow of the stripping steam is regulated according to the quality requirements of a downstream device on the light oil product at the top of the tower and the heavy oil product at the bottom of the tower.

4. The control part of the separation tower comprises tower top pressure control, flash evaporation temperature control, liquid level control in the tower and heat insulation measures of the device;

the pressure control of the tower top is controlled by a control system composed of a regulating valve arranged on a tower top gas product pipeline and a pressure transmitter at the tower top;

the gas phase components separated by the separating tower are a mixture containing light oil fraction and vapor, but are jointly output as a raw material gas phase state of a downstream device;

the liquid level in the tower and the regulating valve and flowmeter set on the tower bottom product pipeline constitute the liquid level-flow cascade control system.

The beneficial effects are that:

the invention relates to a pressure flash evaporation device which is a non-side line extraction system, a non-tower top condensation separation system and a non-side line rectifying tower, wherein the non-side line rectifying tower can separate crude oil into light fraction and heavy fraction; the fractionation accuracy of two components of crude oil can be achieved by using a small number of matched facilities; adopting a pressurized flash evaporation mode to separate two components of the crude oil which is a wide boiling range medium and communicate the two components with the pressure of a downstream device system; the invention breaks through the conventional normal and reduced pressure distillation tower process, adopts simple process flow, has less matched equipment and greatly reduces the investment amount.

Drawings

FIG. 1 is a schematic view of the process of example 1 of the present invention;

FIG. 2 is a schematic process diagram of embodiment 2 of the present invention;

the numbering in the figures is as follows:

f0 crude oil, T0 separation column, 20 crude oil heating or heat exchange equipment, 30 trays or packing; an R catalytic cracking reactor, an R2 second catalytic cracking reactor; 11 crude oil stream entering the column (i.e., crude oil heated to form a stream entering the separation column); 12 steam or water, 13 cold reflux stream, 14 bottoms component, 15 overhead component or effluent overhead gas stream, 16 pressure or flow regulating valve, 17 cold reflux water, FRC flow record control signal, LC level control signal, PIC pressure indication control signal.

Detailed Description

The following specific examples are given to illustrate the technical aspects of the present invention, but the scope of the present invention is not limited thereto.

Example 1:

as shown in FIG. 1, using Daqing oilfield crude oil F0, 300t/h, requires a 95% TBP (tributyl phosphate) of the petroleum hydrocarbon fraction in the overhead component gas of 200 ℃; the implementation is as follows:

the flash pressure of the separation tower T0 is 0.26MPa (a), the diameter is 2600mm, and 6 layers of floating valve trays 30 are arranged in the separation tower T0;

the crude oil F0 from the desalting and dewatering device enters the device under the pressure of 0.3MPa (a), the temperature of 120 ℃, the crude oil is heated to 200 ℃ in the crude oil heating or heat exchanging equipment 20, and enters the separation tower T0 as the crude oil flow 11 entering the tower, the superheated steam 12 with the temperature of 250 ℃ is injected into the bottom of the separation tower, and the steam injection amount is 6T/h; simultaneously, catalytic cracking gas sewage, namely cold reflux water 17 and crude oil before heating are used as cold reflux streams 13, wherein 4.5T/h of cold reflux stream sewage enters a separation tower T0 from the top of a tray, and 10T/h of crude oil at 120 ℃ enters the separation tower T0 from the bottom of a second tray from top to bottom;

the overhead component 15, i.e. the effluent overhead gas stream 29.5t/h, is fed out of the apparatus, with 19t/h of petroleum hydrocarbons; the bottom component 14, i.e. the bottom liquid petroleum hydrocarbon 281t/h, is fed out of the apparatus.

Example 2:

as shown in FIG. 2, daqing crude oil is 300t/h, and naphtha components are separated. The implementation is as follows:

the crude oil F0 is subjected to heat exchange to 270 ℃ in a crude oil heating or heat exchange device 20, and is taken as an incoming crude oil stream 11 to enter a separation tower T0, 6 layers of floating valve trays 30 are arranged in the separation tower, the pressure of the top of the separation tower is 0.26MPa (a), and superheated steam 12 at 250 ℃ enters the separation tower T0 from a liquid zone at the bottom of the separation tower at a speed of 6T/h; using 120 ℃ crude oil as a cold reflux stream 13, wherein the cold reflux stream enters a separation tower in two layers, 4.5t of crude oil enters the separation tower from above a tower top tray, and 10.5t/h of crude oil enters the separation tower from below a second layer of trays from top to bottom; the flow rate of the tower top component 15, namely the tower top gas phase, is 42t/h, and the flow rate of the low boiling point component petroleum hydrocarbon in crude oil is 36t/h; bottom component 14 liquid 264t/h. The liquid separation column bottom component 14 enters the catalytic cracking reactor R through a pipeline; the gas state of the low boiling point separation tower top component 15 enters a catalytic cracking second reactor R2 through a pipeline;

otherwise, the same as in example 1 was used.

Claims (8)

1. A crude oil bi-component pre-separation method is characterized in that desalted and dehydrated crude oil enters a pressurizing separation tower after being preheated in a heating furnace or heat exchange equipment, and low-boiling-point components are gasified and separated into gas-phase components and high-boiling-point liquid-phase components, and the specific process is as follows:

(1) Pressurizing and preheating desalted and dehydrated crude oil (F0), forming a crude oil stream (11) entering a tower partially or completely, entering a separation tower (T0), gasifying low-boiling components in the crude oil in the separation tower (T0), enabling the gasified gas stream to flow upwards, and settling unvaporized high-boiling components to the bottom of the separation tower;

(2) Entering a liquid cold reflux stream (13) at a temperature not greater than 250 ℃ in the upper part of the separation column;

alternatively, a portion of the crude oil (F0) is split off before heating and introduced into the separation column (T0) from the top as a cold reflux stream; alternatively, a portion of the high boiling components from the bottom of the column is cooled and fed as a cold reflux stream from the top zone to the separation column (T0); or/and, using water as cold reflux stream into the separation column (T0) from the top;

the cold reflux stream (13) is mixed with the gasified ascending gas stream in the crude oil stream (11) in the top region of the separation tower (T0) and cooled, the high-boiling components in the gasified gas stream in the crude oil stream (11) in the separation tower are liquefied again, the liquefied part flows downwards together with the high-boiling components in the cold reflux stream (13), the liquefied part is continuously mixed with the ascending gas below to reduce the content of the high-boiling components in the gas components, the liquid part returns to the high-boiling components at the bottom of the separation tower, the low-boiling gas phase components at the top of the separation tower, namely, the top component (15) of the separation tower flows out from the separation tower (T0), and the high-boiling liquid phase components, namely, the bottom component (14) of the separation tower flow out from the bottom of the separation tower;

the temperature of the crude oil stream entering the column or the operating pressure of the separation column or the flow rate of the cold reflux stream is varied to control the composition and flow rate ratio of the separated overhead component (15) and bottom component (14).

2. The crude oil two-component pre-separation process of claim 1, wherein: steam or water is injected before or after the crude oil is heated and enters the separation tower, or steam or water is injected into the lower liquid phase component in the separation tower.

3. The crude oil two-component pre-separation process of claim 1, wherein: water is used as a cold reflux stream of the separation tower (T0), and the cold reflux water (17) enters the separation tower (T0) from the top area or/and the middle part of the separation tower, is mixed with the gasified ascending gas in the crude oil stream (11) entering the tower and is cooled, so that high-boiling components in gasified components are liquefied.

4. The crude oil two-component pre-separation process of claim 1, wherein: the crude oil (F0) is preheated to 200 ℃ to 380 ℃ when entering a separation tower (T0), and the pressure is 250Kpa (absolute) to 1.3Mpa (absolute); the pressure at the top of the separation tower ranges from 230Kpa (absolute) to 460Kpa (absolute).

5. A crude oil bi-component preseparation device, characterized in that: the device is provided with crude oil heat exchange or heating equipment (20) and a separation tower (T0); the separation tower (T0) is vertical, the bottom is provided with a tower bottom component liquid outlet, the top is provided with a tower top component gas outlet, the lower part of the outer side is provided with a tower inlet crude oil stream inlet, a steam or water inlet is arranged below the tower inlet crude oil stream inlet, and the top or/and the middle is provided with a cold reflux stream inlet; connecting pipelines between the inlet of the crude oil stream entering the tower and the heat exchange or heating equipment (20) and the separation tower (T0); the cold reflux stream inlet is communicated with an upstream pipeline of the heat exchange or heating equipment (20) so that crude oil enters the top of the separation tower from the cold reflux stream inlet before entering the heat exchange or heating equipment; a pressure regulating valve is arranged on a component gas pipeline at the top of the fractionating tower so as to control the operating pressure at the top of the separating tower.

6. The crude oil two-component preseparation apparatus as defined in claim 5, wherein: water inlets are arranged at the middle part and/or the upper part of the separation tower (T0) so as to introduce cold reflux water.

7. The crude oil two-component preseparation apparatus as defined in claim 5, wherein: a tray or packing is provided in the separation column (T0) below the cold reflux stream inlet.

8. The crude oil two-component preseparation apparatus as defined in claim 5, wherein: and a packing or tray or liquid coalescing equipment is arranged below the top outlet of the separation tower (T0) or above the inlet of the cold reflux stream.

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