A waxy crude oil cold transportation device and method of use thereof

Abstract

The present application relates to the technical field of oil conveying device, and particularly relates to a waxy crude oil cold conveying device, which comprises an oil storage tank and a cooling oil tank; a refrigeration device is arranged on the periphery of the cooling oil tank; a stirrer and a second temperature sensor are arranged in the cooling oil tank; the refrigeration device comprises an outer frame, a refrigeration pipe, a natural gas pipeline, an expander and a first heat exchanger; the refrigeration pipe comprises a surrounding part and a line part; the surrounding part is located inside the outer frame and surrounds the outer wall of the cooling oil tank; the line part is located outside the outer frame; the line part exchanges heat with the natural gas pipeline at the first heat exchanger; and a fourth temperature control valve is arranged on the line part. The present application also provides a waxy crude oil cold conveying method. The present application can prepare a uniform wax crystal suspension, thereby avoiding the wax deposition phenomenon in the pipeline, effectively solving the blockage problem of the crude oil conveying pipeline, saving the pigging cost; the natural gas in the natural gas pipeline is used for expansion heat exchange, thereby saving the refrigeration energy consumption and refrigeration cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil conveying device, in particular to a waxy crude oil cold conveying device and a using method thereof. BACKGROUND

[0002] Waxy crude oil refers to the crude oil containing paraffin wax, which is a white or light yellow solid composed of high alkanes, and the melting point is 37-76℃. Paraffin wax is dissolved in petroleum in colloidal form underground, and can be precipitated from petroleum when the pressure and temperature decrease. The temperature at which paraffin in the formation crude oil begins to crystallize and precipitate is called wax precipitation temperature. During the conveying process of waxy crude oil, as the conveying distance is prolonged, the oil temperature is continuously reduced, and when the temperature is reduced below the wax precipitation temperature, wax molecules are continuously precipitated from the crude oil and form crystals, and the paraffin crystals grow continuously, and finally deposit on the pipe wall. The deposition of paraffin greatly affects the conveying capacity and efficiency of the pipeline, and is prone to pipeline blockage and other dangers.

[0003] Chinese patent CN201410741052.4 discloses a waxy crude oil conveying pipeline, which is provided with a magnetic impeller inside the metal pipeline. The flow of the crude oil inside the pipeline drives the magnetic impeller to rotate at high speed, and the magnetic impeller periodically changes the magnetic field at the pipe wall of the metal pipeline. The pipe wall of the metal pipeline generates induced eddy current under the action of the alternating magnetic field of the magnetic impeller and heats itself, thereby realizing heating of the waxy crude oil inside the metal pipeline. The invention saves the construction cost of the heating furnace and the pig launcher-receiver device in the prior art, and reduces the daily operation cost of the oil conveying pipeline. However, the invention still has many problems in use, such as the inability to monitor and adjust the temperature of the waxy crude oil; the magnetic impeller inside the pipeline increases the friction loss during the conveying process of the waxy crude oil, and is not conducive to the passage of the pig.

[0004] Chinese patent CN201220064966.8 discloses a set of oil cold delivery electromagnetic thermostat control device, the device adopts the pipe body to be the reinforced plastic composite pipe, the pipe body wall is provided with the steel mesh and the temperature controller, the steel mesh two ends are connected with the control box inside direct current high frequency oscillation electromagnetic power supply through the wire, the temperature controller is connected with the control circuit in the control box through the wire structure; the temperature controller is used for collecting the crude oil temperature in the pipe body, the steel mesh is opened or closed through the control circuit in the control box, when the temperature in the pipe body is higher than the infusion temperature setting value, the control circuit in the control box controls the steel mesh to stop heating, when the temperature in the pipe body is lower than the infusion temperature setting value, the control circuit in the control box controls the steel mesh to start heating, when the steel mesh passes through the electromagnetic, the steel mesh will generate certain heat energy, the pipeline will quickly form heat, and the liquid in the pipe body is heated.The invention can realize the constant temperature transportation of the pipe body, thereby reducing the energy consumption and management cost, and guaranteeing the gathering and transportation effect.But the reinforced plastic composite pipe used in the invention is not suitable for some pipelines with large conveying pressure, and the steel mesh and the temperature controller in the pipe body wall have higher investment cost than ordinary steel pipes, and the heating power is provided by electric energy, so the energy consumption of the conveyed oil is high.

[0005] In recent years, domestic and foreign scholars have proposed the concept of cold transportation for wax deposition prevention of waxy oil pipeline transportation, which is a new technology that can control and reduce wax deposition problems of waxy oil during flow. First, the waxy oil is cooled to below the wax precipitation temperature but above the freezing point temperature, at which time the wax molecules precipitated in the crude oil will be suspended in the crude oil, and then the suspension will not cause wax deposition problems when transported in a low-temperature environment. The preparation of wax crystal suspension requires cooling to below the wax precipitation temperature, so it is necessary to develop a device that can realize the cold transportation of waxy crude oil.

[0006] Therefore, it is urgent to design a waxy crude oil cold transportation device and its use method, which can treat waxy crude oil before transportation into crude oil containing uniformly distributed wax microcrystals, thereby avoiding the deposition of wax in waxy crude oil to block the pipeline in subsequent pipeline transportation. SUMMARY

[0007] To solve the above problems, the present application provides a waxy crude oil cold transportation device, the technical scheme is as follows:

[0008] A waxy crude oil cold transportation device, comprising a storage tank and a cooling oil tank; a first temperature sensor is arranged on the storage tank, and a refrigeration device is arranged around the cooling oil tank; the storage tank is connected with an oil inlet pipeline, a first oil conveying pipe is connected between the storage tank and the cooling oil tank, and the cooling oil tank is connected with a second oil conveying pipe; a stirrer and a second temperature sensor are arranged in the cooling oil tank;

[0009] The refrigeration device comprises an outer frame, a refrigeration pipe, a natural gas pipeline, an expander and a first heat exchanger, the refrigeration pipe comprises a surrounding part and a line part, the surrounding part is located inside the outer frame, the surrounding part surrounds the outer wall of the cooling oil tank, and the line part is located outside the outer frame; the expander and the first heat exchanger are sequentially arranged on the natural gas pipeline in the transportation direction of the natural gas, the line part exchanges heat with the natural gas pipeline at the first heat exchanger; a fourth temperature control valve is arranged on the line part, and the temperature value detected by the second temperature sensor is used to control the fourth temperature control valve.

[0010] Further, a first conveying pump and a first temperature control valve are arranged on the first oil conveying pipe, the temperature value measured by the first temperature sensor is T1, when 25℃≤T1≤35℃, the first conveying pump, the first temperature control valve and the agitator are opened.

[0011] Further, it further comprises a heat preservation oil tank, a heat preservation layer is arranged on the outer wall of the heat preservation oil tank, the heat preservation oil tank is connected with the second oil conveying pipe, and the heat preservation oil tank is connected with the third oil conveying pipe.

[0012] Further, a second conveying pump is arranged on the second oil conveying pipe, and a third conveying pump is arranged on the third oil conveying pipe; a second temperature control valve is arranged on the second oil conveying pipe, a third temperature control valve is arranged on the third oil conveying pipe, and a fifth temperature control valve is arranged on the natural gas pipeline.

[0013] Further, the temperature value measured by the second temperature sensor is T2,

[0014] When the condensation point temperature≤T2≤wax precipitation temperature, the second conveying pump and the third conveying pump are opened, the opening degree of the second temperature control valve is 100%, the opening degree of the third temperature control valve is 100%, the opening degree of the fourth temperature control valve is 60%, and the opening degree of the fifth temperature control valve is 80%;

[0015] When the wax precipitation temperature≤T2≤25℃, the second conveying pump and the third conveying pump are closed, the second temperature control valve is closed, the third temperature control valve is closed, the opening degree of the fourth temperature control valve is 100%, and the opening degree of the fifth temperature control valve is 100%.

[0016] Further, the oil storage tank is an open oil tank, and the cooling oil tank and the heat preservation oil tank are both closed oil tanks.

[0017] Further, a first pressure gauge, a second pressure gauge and a flowmeter are sequentially arranged on the second oil conveying pipe, the pressure value measured by the first pressure gauge is P1, the pressure value measured by the second pressure gauge is P2, the flow rate of the crude oil measured by the flowmeter is V1, and the equivalent viscosity of the waxy crude oil contained in the second oil conveying pipe is μ:

[0018]

[0019] Wherein, d is the inner diameter of the second oil pipeline, and L is the length of the pipeline between the two pressure gauges.

[0020] Further, the refrigeration device further comprises a second heat exchanger, which is arranged behind the first heat exchanger in the transportation direction of the natural gas.

[0021] Further, the surrounding part spirally surrounds the outer wall of the cooling oil tank.

[0022] Further, the second temperature sensor is connected to a temperature transmitter, which converts the measurement data of the second temperature sensor into temperature data.

[0023] The application also provides a waxy crude oil cooling transportation method, which uses the waxy crude oil cooling transportation device and specifically comprises the following steps:

[0024] S1, the waxy crude oil is introduced into the oil storage tank, and the outer frame is filled with water;

[0025] S2, the fourth temperature control valve, the fifth temperature control valve, the expander, the first heat exchanger and the second heat exchanger are opened, and the natural gas pipeline is introduced into the natural gas to perform a refrigeration cycle;

[0026] S3, when 25℃≤T1≤35℃, the first temperature control valve, the first conveying pump and the stirrer are opened, the waxy crude oil is introduced into the cooling oil tank, and the preparation of the wax crystal suspension is performed;

[0027] S4, the prepared wax crystal suspension flows into the heat preservation oil tank through the second oil pipeline, and the equivalent viscosity of the wax crystal suspension is calculated according to the pressure values measured by the first pressure gauge and the second pressure gauge and the flow rate value measured by the flowmeter;

[0028] S5, the wax crystal suspension enters the downstream oil pipeline from the heat preservation oil tank through the third oil pipeline.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] 1. The present application can realize accurate preparation of wax crystal suspension by setting first and second temperature sensors, controlling the temperature in the oil tank within a certain range to prepare the wax crystal suspension, and adjusting the refrigeration efficiency and the flow of crude oil by controlling the opening of several temperature control valves using the second temperature sensor.

[0031] 2. The present application can save refrigeration energy consumption and refrigeration cost by setting the oil tank, the cooling oil tank and the heat preservation oil tank, and using natural gas in the natural gas pipeline for expansion heat exchange. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the present application.

[0033] Marked with reference numerals:

[0034] 1- oil tank; 2- first delivery pump; 3- first temperature control valve; 4- cooling oil tank; 5- outer frame; 6- stirrer; 7- temperature transmitter; 8- fourth temperature control valve; 9- refrigeration pipe; 10- fifth temperature control valve; 11- expander; 12- first heat exchanger; 13- natural gas pipeline; 14- second heat exchanger; 15- second delivery pump; 16- second temperature control valve; 17- first pressure gauge; 18- second pressure gauge; 19- flow meter; 20- heat preservation oil tank; 21- third temperature control valve; 22- third delivery pump; 23- first temperature sensor, 24- second temperature sensor, 25- first oil pipe, 26- second oil pipe, 27- third oil pipe. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are not all the embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application. It should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0036] As Figure 1As shown, the present application provides a kind of wax-containing crude oil cold transport device, including oil tank 1 and cooling oil tank 4;First temperature sensor 23 is arranged on the oil tank 1, and refrigeration device is arranged on the periphery of the cooling oil tank 4;The oil tank 1 is connected to the oil inlet pipeline, and the oil tank 1 is connected with the first oil conveying pipe 25 between the cooling oil tank 4, and the cooling oil tank 4 is connected with the second oil conveying pipe 26;Stirrer 6 and second temperature sensor 24 are arranged in the cooling oil tank 4;

[0037] The refrigeration device includes frame 5, refrigeration pipe 9, natural gas pipeline 13, expander 11 and first heat exchanger 12, the refrigeration pipe 9 includes a surrounding portion and a line portion, the surrounding portion is located inside the frame 5, and the surrounding portion is surrounded along the outer wall of the cooling oil tank 4, and the line portion is located outside the frame 5;Along the transport direction of natural gas, the expander 11 and the first heat exchanger 12 are sequentially arranged on the natural gas pipeline 13, and the line portion exchanges heat with the natural gas pipeline 13 at the first heat exchanger 12;Fourth temperature control valve 8 is arranged on the line portion.

[0038] The oil tank 1 is an open oil tank, after the wax-containing crude oil enters the oil tank 1, the heat exchange of the outer wall and the opening of the oil tank 1 is cooled, the first oil conveying pipe 25 is provided with first conveying pump 2 and first temperature control valve 3, the temperature value measured by the first temperature sensor 23 is T1, when 25 ℃≤T1≤35 ℃, the first conveying pump 2, the first temperature control valve 3 and the stirrer 6 are opened, and the wax-containing crude oil enters the cooling oil tank 4 through the first oil conveying pipe 25.

[0039] The wax-containing crude oil cold transport device of the present application further comprises a heat preservation oil tank 20, a heat preservation layer is arranged on the outer wall of the heat preservation oil tank 20, the heat preservation oil tank 20 is connected with the second oil conveying pipe 26, the heat preservation oil tank 20 is connected with the third oil conveying pipe 27, and the heat preservation oil tank 20 plays a buffering role to balance the preparation efficiency of the cooling oil tank 4 and the transportation efficiency of the oil conveying pipeline.

[0040] Second conveying pump 15 is arranged on the second oil conveying pipe 26, third conveying pump 22 is arranged on the third oil conveying pipe 27;Second temperature control valve 16 is arranged on the second oil conveying pipe 26, third temperature control valve 21 is arranged on the third oil conveying pipe 27, fifth temperature control valve 10 is arranged on the natural gas pipeline 13, and the temperature value measured by the second temperature sensor 24 is T2,

[0041] When the freezing point temperature≤T2≤wax precipitation temperature, the second conveying pump 15 and the third conveying pump 22 are opened, the opening degree of the second temperature control valve 16 is 100%, the opening degree of the third temperature control valve 21 is 100%, the opening degree of the fourth temperature control valve 8 is 60%, and the opening degree of the fifth temperature control valve 10 is 80%;

[0042] When the wax precipitation temperature is ≤ T2 ≤ 25℃, the second conveying pump 15 and the third conveying pump 22 are closed, the second temperature control valve 16 is closed, the third temperature control valve 21 is closed, the opening degree of the fourth temperature control valve 8 is 100%, and the opening degree of the fifth temperature control valve 10 is 100%; at this time, no crude oil is cold transported, but the temperature of the crude oil is reduced to below the wax precipitation temperature after heat exchange, and then the cold transportation of the crude oil is carried out.

[0043] Preferably, the cooling oil tank 4 and the heat preservation oil tank 20 are both closed oil tanks.

[0044] Preferably, the first pressure gauge 17, the second pressure gauge 18 and the flowmeter 19 are sequentially arranged on the second oil conveying pipe 26, the pressure value measured by the first pressure gauge 17 is P1, the pressure value measured by the second pressure gauge 18 is P2, the flow rate of the crude oil measured by the flowmeter 19 is V1, and the equivalent viscosity of the waxy crude oil contained in the second oil conveying pipe 26 is μ:

[0045]

[0046] Wherein, d is the inner diameter of the second oil conveying pipe, and L is the pipe length between the two pressure gauges; the calculated equivalent viscosity of the waxy crude oil can provide a reference for the subsequent cold transportation process of the waxy crude oil.

[0047] The refrigeration device further comprises a second heat exchanger 14, which is arranged at the rear end of the first heat exchanger 12 in the transportation direction of the natural gas, thereby further increasing the heat exchange efficiency.

[0048] Preferably, the surrounding part spirally surrounds the outer wall of the cooling oil tank 4, the outer frame 5 is filled with cooling water, and the refrigerant in the surrounding part spirally flows through, so that the cooling water is cooled, and the cooled cooling water cools the cooling oil tank 4.

[0049] Preferably, the second temperature sensor 24 is connected to a temperature transmitter 7, and the temperature transmitter 7 converts the measurement data of the second temperature sensor 24 into temperature data.

[0050] The application also provides a waxy crude oil cold transportation method using the above-mentioned waxy crude oil cold transportation device, and the specific steps are as follows:

[0051] S1, the waxy crude oil is introduced into the oil storage tank 1, and the outer frame 5 is filled with water;

[0052] S2, the fourth temperature control valve 8, the fifth temperature control valve 10, the expander 11, the first heat exchanger 12 and the second heat exchanger 14 are opened, and the natural gas is introduced into the natural gas pipeline 13 to carry out refrigeration cycle;

[0053] S3, when 25℃≤T1≤35℃, the first temperature control valve 3, the first delivery pump 2 and the agitator 6 are opened, and the waxy crude oil enters the cooling oil tank 4 to prepare the wax crystal suspension;

[0054] S4, the prepared wax crystal suspension flows into the heat preservation oil tank 20 through the second oil pipe 26, and the equivalent viscosity of the wax crystal suspension is calculated according to the pressure values measured by the first pressure gauge 17 and the second pressure gauge 18 and the flow rate value measured by the flowmeter 19;

[0055] S5, the wax crystal suspension enters the downstream oil pipeline through the third oil pipe 27 from the heat preservation oil tank 20.

[0056] The above specific embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the examples, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A waxy crude oil cold transportation device, comprising a storage tank and a cooling tank; a first temperature sensor is arranged on the storage tank, and a refrigeration device is arranged on the periphery of the cooling tank; the storage tank is connected with an oil inlet pipeline, a first oil transportation pipeline is connected between the storage tank and the cooling tank, and the cooling tank is connected with a second oil transportation pipeline; a stirrer and a second temperature sensor are arranged in the cooling tank; characterized in that: the refrigeration device comprises an outer frame, a refrigeration pipeline, a natural gas pipeline, an expander and a first heat exchanger; the refrigeration pipeline comprises a surrounding part and a line part; the surrounding part is located inside the outer frame and surrounds the outer wall of the cooling tank; the line part is located outside the outer frame; the expander and the first heat exchanger are sequentially arranged on the natural gas pipeline in the transportation direction of the natural gas; the line part exchanges heat with the natural gas pipeline at the first heat exchanger; a fourth temperature control valve is arranged on the line part, and the temperature value detected by the second temperature sensor is used to control the fourth temperature control valve; a first delivery pump and a first temperature control valve are arranged on the first oil transportation pipeline; the temperature value detected by the first temperature sensor is T1; when 25℃≤T1≤35℃, the first delivery pump, the first temperature control valve and the stirrer are turned on; a heat preservation tank is further arranged, a heat preservation layer is arranged on the outer wall of the heat preservation tank, the heat preservation tank is connected with the second oil transportation pipeline, and the heat preservation tank is connected with a third oil transportation pipeline; a second delivery pump is arranged on the second oil transportation pipeline, a third delivery pump is arranged on the third oil transportation pipeline; a second temperature control valve is arranged on the second oil transportation pipeline, a third temperature control valve is arranged on the third oil transportation pipeline, and a fifth temperature control valve is arranged on the natural gas pipeline; the temperature value detected by the second temperature sensor is T2; when the freezing point temperature≤T2≤wax precipitation temperature, the second delivery pump and the third delivery pump are turned on, the opening degree of the second temperature control valve is 100%, the opening degree of the third temperature control valve is 100%, the opening degree of the fourth temperature control valve is 60%, and the opening degree of the fifth temperature control valve is 80%; when the wax precipitation temperature≤T2≤25℃, the second delivery pump and the third delivery pump are turned off, the second temperature control valve is turned off, the third temperature control valve is turned off, the opening degree of the fourth temperature control valve is 100%, and the opening degree of the fifth temperature control valve is 100%. The storage tank is an open tank, and the cooling tank and the heat preservation tank are both closed tanks. A first pressure gauge, a second pressure gauge and a flow meter are sequentially arranged on the second oil transportation pipeline; the pressure value detected by the first pressure gauge is P1, the pressure value detected by the second pressure gauge is P2, the flow rate of the crude oil detected by the flow meter is V1, and the equivalent viscosity of the waxy crude oil in the second oil transportation pipeline is μ; wherein, d is the pipeline inner diameter of the second oil transportation pipeline, and L is the pipeline length between the two pressure gauges. The refrigeration device further comprises a second heat exchanger, which is arranged behind the first heat exchanger in the transportation direction of the natural gas. The surrounding part spirally surrounds the outer wall of the cooling tank. The device comprises the following steps: ​ ​ 2. The waxy crude oil cold transportation apparatus according to claim 1, characterized in that: ​ 3. The waxy crude oil cold transportation apparatus according to claim 2, characterized in that: ​ ​ 4. The waxy crude oil cold transportation apparatus according to claim 3, characterized in that: ​ 5. The waxy crude oil cold transportation apparatus according to claim 4, characterized in that: ​ 6. A method for cold transportation of waxy crude oil using the waxy crude oil cold transportation apparatus according to any one of claims 4 or 5, characterized by: ​ S1, the oil tank is filled with wax-containing crude oil, and the outer frame is filled with water; S2, open the fourth temperature control valve, the fifth temperature control valve, the expander, the first heat exchanger, the second heat exchanger, and the natural gas pipeline is filled with natural gas for refrigeration cycle; S3, when 25℃≤T1≤35℃, open the first temperature control valve, the first conveying pump and the stirrer, the wax-containing crude oil enters the cooling oil tank, and the preparation of wax crystal suspension is carried out; S4, the prepared wax crystal suspension flows into the heat preservation oil tank through the second oil pipe, at the same time, according to the pressure values measured by the first pressure gauge and the second pressure gauge, and the flow rate value measured by the flowmeter, the equivalent viscosity of the wax crystal suspension is calculated; S5, the wax crystal suspension enters the downstream oil pipeline through the third oil pipe from the heat preservation oil tank.

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