CN115577216B - Supercritical carbon dioxide pipeline long-distance conveying phase state control system and method - Google Patents
Supercritical carbon dioxide pipeline long-distance conveying phase state control system and method Download PDFInfo
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 56
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 28
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims description 29
- 238000002347 injection Methods 0.000 claims abstract description 5
- 239000007924 injection Substances 0.000 claims abstract description 5
- 239000007788 liquid Substances 0.000 claims description 22
- 238000005259 measurement Methods 0.000 claims description 18
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 230000001133 acceleration Effects 0.000 claims description 6
- 230000005484 gravity Effects 0.000 claims description 6
- 238000005457 optimization Methods 0.000 claims description 6
- 230000002035 prolonged effect Effects 0.000 claims description 6
- 239000007789 gas Substances 0.000 description 48
- 238000010586 diagram Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
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Abstract
The invention discloses a supercritical carbon dioxide pipeline long-distance conveying phase state control system, which comprises a long-distance pipeline system, wherein an inlet of the long-distance pipeline system is connected with a front supercharging device of the pipeline system, and an outlet of the long-distance pipeline system is connected with an injection well; the long-distance pipeline system comprises a pipeline and a plurality of pipeline system booster pumps arranged on the pipeline, and the pressure at the inlets of the pipeline system booster pumps is configured to be 10.32MPa; the inlet and the outlet of each pipeline system booster pump are respectively provided with a pressure sensor; the arrangement position of each pipeline system booster pump is obtained by a pressure drop gradient formula; if the pipeline is judged to leak, the pressure drop gradient formula is also utilized to determine the position of the leakage point. The invention can jointly determine the arrangement position of each pipeline system booster pump and the leakage position of the long-distance pipeline through the pressure drop gradient formula, and has high engineering application value.
Description
Technical Field
The present invention relates to CO 2 In particular to a phase control system and a method for long-distance transportation of supercritical carbon dioxide pipelines.
Background
CO 2 Is of critical importance for controlling carbon emissions. Due to the trapped CO 2 Often far from the injection site, the pipeline is transported to form CO by large transportation quantity and long transportation distance 2 The most economical route of delivery. For large-volume and long-distance conveying pipelines, supercritical phase conveying or dense phase conveying is preferably adopted.
CO 2 In long distance pipeline transportation, CO is required to be maintained 2 And the medium is transported in the pipeline with pressure drop. That is, it is necessary to arrange a booster pump in the long-distance piping system. For supercritical CO 2 It is not practical to obtain the number and positions of the arrangement of the booster pumps through experiments. Thus, CO 2 Accurate calculation of supercritical phase conveying pipeline pressure and pressurization of long-distance pipeline systemThe arrangement of the pump is of great importance.
In addition, CO 2 In the long-distance pipeline conveying process, if the pipeline leaks, released CO 2 The gas state is quickly recovered, and the environment is influenced. Thus, for supercritical CO 2 It is also important to quickly determine the point of leakage for quick action.
Therefore, how to provide a supercritical carbon dioxide pipeline long-distance conveying phase control system and method capable of accurately calculating the arrangement number and positions of booster pumps and rapidly determining leakage points is a technical problem to be solved in the art.
Disclosure of Invention
The invention adopts the following technical scheme:
in a first aspect, the invention adopts a supercritical carbon dioxide pipeline long-distance conveying phase control system, which comprises a long-distance pipeline system, wherein an inlet of the long-distance pipeline system is connected with a front supercharging device of the pipeline system, and an outlet of the long-distance pipeline system is connected with an injection well;
the long-distance pipeline system comprises a pipeline and a plurality of pipeline system booster pumps arranged on the pipeline, and the pressure at the inlets of the pipeline system booster pumps is configured to be 10.32MPa;
the inlet and the outlet of each pipeline system booster pump are respectively provided with a pressure sensor;
the arrangement position of each pipeline system booster pump is obtained by a pressure drop gradient formula;
wherein if itThe ith pipeline system booster pump normally operates according to the calculated value of the pressure drop gradient formula;
if it isThe pressurizing time of the i-th pipeline system booster pump is prolonged appropriately according to the measured value of the pressure sensor at the inlet of the i-th pipeline system booster pump;
if it isAnd->Judging that the pipeline leaks, and determining the position of a leakage point by using the pressure drop gradient formula;
wherein n-1 is the number of booster pumps of the pipeline system;
p (i,1) calculating a pressure at the inlet of the booster pump of the ith pipeline system;the measured value of the pressure sensor at the inlet of the booster pump of the ith pipeline system; p is p (i-1,2) Calculating a pressure value at the outlet of the i-1 th pipeline system booster pump;the measured value of the pressure sensor at the outlet of the booster pump of the i-1 th pipeline system;
ε 1 to determine whether a threshold value of the pressurizing time length of the i-th pipeline system booster pump needs to be adjusted; epsilon 2 Epsilon 3 To determine x between the ith and the (i-1) th pipeline system booster pumps i A threshold for whether a leak occurs in a length of tubing.
Further, the pipeline system front booster device comprises a carbon dioxide compressor, a cooler and a pipeline system front booster pump which are sequentially connected through pipelines;
carbon dioxide compressor and CO 2 The exhaust port of the air source is connected;
the outlet of the front booster pump of the pipeline system is connected with the long-distance pipeline system;
wherein the carbon dioxide compressor compresses CO 2 The gas is compressed to the outlet pressure lower than the supercritical state, and the cooler isobarically cools CO 2 Booster pump before pipeline system for CO 2 Pressurizing to a supercritical state.
Further, the twoCarbon oxide compressor CO 2 Compressing the gas to 8.9-9.3 MPa.
Further, the booster pump before the pipeline system boosts CO 2 Pressurizing to a supercritical state of 15-18 MPa.
Further, the pressure drop gradient formula is:
wherein H is L For the liquid content of the cross section,is of liquid density, kg/m 3 ；/>Is of gas density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the θ is the angle of inclination of the pipe, rad; omega is the gas-liquid mixing speed, m/s; g is the mass flow of the liquid-gas mixture, kg/s; d is the inner diameter of the pipeline, m; omega sg Is the gas phase conversion speed, m/s; p is the average absolute pressure of the dl section pipeline and Pa; lambda is the liquid-gas mixing friction coefficient.
Further, the liquid-gas mixing friction coefficient is as follows:
λ＝kλ 0 e n
wherein k is a correction coefficient, lambda 0 A hydrodynamic friction coefficient for uniform flow;
wherein, establishing an optimization model to solve k:
Find k
wherein Δp is the actual pressure drop; Δp (k) is defined as λ=kλ 0 e n Calculating the theoretical pressure drop after the hydraulic friction coefficient; n is the number of conduit pressure drop samples; f (k) is the sum of the square deviation of the actual pressure drop and the theoretical pressure drop.
Further, the method comprises the steps of,if it is determined that the pipeline has leakage, x i Leakage occurs in the length of pipe;
wherein x is i The leakage point of the length of pipeline is obtained by the pressure drop gradient formula:
through the actual measurement value of the pressure sensor at the outlet of the i-1 th pipeline system booster pumpObtaining x of the pipeline by using the pressure drop gradient formula i A forward curve S1 of the length segment;
by actual measurement of pressure sensor at inlet of booster pump of ith pipeline systemObtaining x of the pipeline by using the pressure drop gradient formula i A reverse curve S2 of the length segment;
the intersection point of the forward curve S1 and the reverse curve S2 is the x of the pipeline i Leakage points of the length sections.
In a second aspect, the present invention provides a method for controlling a long-distance conveying phase of a supercritical carbon dioxide pipeline, which is used for the long-distance conveying phase control system of a supercritical carbon dioxide pipeline, and includes the following steps:
step 1, increasing the pressure at the inlet of a long-distance pipeline system to 15-18 MPa through a carbon dioxide compressor and a booster pump in front of the pipeline system;
step 2, determining the arrangement positions and the number of the booster pumps of the pipeline system according to a pressure drop gradient formula, so that the pressure at the inlet of each booster pump of the pipeline system is 10.32MPa;
wherein, the pressure drop gradient formula is:
wherein H is L For the liquid content of the cross section,is of liquid density, kg/m 3 ；/>Is of gas density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the θ is the angle of inclination of the pipe, rad; omega is the gas-liquid mixing speed, m/s; g is the mass flow of the liquid-gas mixture, kg/s; d is the inner diameter of the pipeline, m; omega sg Is the gas phase conversion speed, m/s; p is the average absolute pressure of the dl section pipeline and Pa; lambda is the liquid-gas mixed friction coefficient;
step 3, controlling the long-distance pipeline system through pressure sensors at the inlet and the outlet of each pipeline system booster pump:
if it isThe ith pipeline system booster pump normally operates according to the calculated value;
if it isThe pressurizing time of the i-th pipeline system booster pump is prolonged appropriately according to the measured value of the pressure sensor at the inlet of the i-th pipeline system booster pump;
if it isAnd->The pressure drop gradient formula is used to determine the location of the leak.
Further, step 3 includes:
step 31, through the actual measurement value of the pressure sensor at the outlet of the i-1 th pipeline system booster pumpObtaining x of pipeline by pressure drop gradient formula i A forward curve S1 of the length segment;
step 32, by the firstActual measurement values of pressure sensors at inlet of i booster pumps of pipeline systemObtaining x of pipeline by pressure drop gradient formula i A reverse curve S2 of the length segment;
step 33, the intersection point of the forward curve S1 and the reverse curve S2 is the x of the pipeline i Leakage points of the length sections.
Further, the liquid-gas mixing friction coefficient is as follows:
λ＝kλ 0 e n
wherein k is a correction coefficient, lambda 0 A hydrodynamic friction coefficient for uniform flow;
wherein, establishing an optimization model to solve k:
Find k
wherein Δp is the actual pressure drop; Δp (k) is defined as λ=kλ 0 e n Calculating the theoretical pressure drop after the hydraulic friction coefficient; n is the number of conduit pressure drop samples; f (k) is the sum of the square deviation of the actual pressure drop and the theoretical pressure drop.
The invention has the following advantages:
(1) Through the pressure drop gradient formula, the arrangement position of each pipeline system booster pump and the leakage position of the long-distance pipeline can be jointly determined, and the method has high engineering application value.
(2) Change CO 2 In the gas pressurizing mode, the final outlet pressure of the carbon dioxide compressor does not reach the critical pressure, and the high-temperature gas at the outlet of the carbon dioxide compressor is cooled to be completely liquefied by a cooler in the aftercooling process, so that a booster pump in front of a pipeline system can obtain higher suction density, and the reduction of pressurizing power consumption is facilitated.
(3) The pressure drop gradient formula of the invention introduces the cross section liquid content, gas density, gas-liquid mixing speed, liquid-gas mixing mass flow and gas phase conversion speedAnd liquid-gas mixed friction coefficient, for supercritical CO mixed with small amounts of CH4 and N2 gases 2 Long-distance pipeline transportation, and more accurate calculation model.
(4) By correcting the pressure drop gradient calculation model, the calculation error of the distance-pressure equation of the length section between two adjacent pipeline system booster pumps is reduced, and the position of each pipeline system booster pump is arranged more accurately.
(5) By using the pressure drop gradient formula, the leakage position of the long-distance pipeline system can be accurately determined.
Drawings
FIG. 1 is a system diagram;
FIG. 2 is a schematic diagram of a long-distance pipeline system;
FIG. 3 is a schematic diagram of a second long-distance pipeline system;
FIG. 4 is a third schematic diagram of a long-distance pipeline system;
FIG. 5 is a pipeline x i Length distance-pressure equation diagram.
Detailed Description
The following detailed description of embodiments of the invention, provided in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention.
As shown in fig. 1, the present embodiment provides a supercritical carbon dioxide pipeline long-distance transportation phase control system, which includes a carbon dioxide compressor 1, a cooler 2, a pipeline system front booster pump 3, a long-distance pipeline system 10 and an injection well, which are sequentially connected through pipelines.
It will be appreciated that the carbon dioxide compressor 1 and the CO 2 The exhaust port of the air source is connected with the CO of the embodiment 2 The gas discharged from the gas source is CO 2 The trapped and purified gas is mixed with a small amount of CH 4 And N 2 And (3) gas.
On a large scale CO 2 Long distanceCO is typically supplied in pipeline 2 The gas is pressurized to a supercritical or dense phase state, so that the method is more economical and efficient. In the present embodiment, CO is fed by a carbon dioxide compressor 1, a cooler 2, and a pipeline system front booster pump 3 2 The gas is pressurized to a supercritical state.
Wherein the carbon dioxide compressor 1 converts CO 2 The gas is compressed to the outlet pressure slightly lower than the supercritical state (the critical pressure value is 9.38 MPa), and the cooler 2 isobarically cools CO 2 The booster pump 3 before the pipeline system boosts CO 2 Pressurizing to a supercritical state.
In the prior art, CO is fed by a compressor 2 The gas is pressurized to be above the critical pressure, after heat exchange by the aftercooler, the density of the fluid is further increased, and then the fluid is pressurized to the pressure of the input port of the pipeline system by the booster pump.
The present embodiment changes CO 2 In the gas pressurizing mode, the final outlet pressure of the carbon dioxide compressor 1 does not reach the critical pressure, and the high-temperature gas at the outlet of the carbon dioxide compressor 1 is cooled to be completely liquefied by the cooler 2 in an isobaric manner in the post-cooling process, so that the booster pump 3 in front of the pipeline system can obtain higher suction density, and the reduction of pressurizing power consumption is facilitated.
Specifically, the carbon dioxide compressor 1 converts CO 2 The gas is compressed to 8.9-9.3 MPa, so that the outlet pressure of the carbon dioxide compressor 1 is slightly lower than the supercritical state.
The front booster pump 3 of the pipeline system boosts CO 2 Pressurizing to a supercritical state of 15-18 MPa to make CO 2 The supercritical state is still satisfied after the pressure drop is generated in the conveying process of the long-distance pipeline system 10, and the pressurizing cost is not excessively high. Preferably, the pre-pipeline system booster pump 3 will supply CO 2 Pressurizing to a supercritical state of 16MPa.
It will be appreciated that supercritical CO 2 During transportation of long-distance pipeline system 10, the pressure of the input port of the pipeline system cannot be too high due to the pressurization cost, and CO is always kept in the whole long-distance pipeline system 10 2 In the supercritical state, thus in practice to make CO 2 Is maintained at least 10.32MPa (critical pressure value) in long-distance pipeline system 101.1 times) or more.
Thus, several booster pumps are required to be arranged in the long-distance pipeline system 10, so that the pressure between the inlet of the long-distance pipeline system and the first booster pump and the pressure between the two adjacent front and rear booster pumps are kept between 16MPa and 10.32MPa.
In the present embodiment, as shown in fig. 2 to 4, the long-distance pipeline system 10 includes a pipeline 100 and a plurality of pipeline system booster pumps 110 provided on the pipeline 100, and the pressure at the inlets of the plurality of pipeline system booster pumps 110 is configured to be 10.32MPa.
Thereby ensuring that the pressure at the inlet of the long-distance piping system 10 to the pressure at the inlet of the first booster pump 110, the pressure at the outlet of the adjacent front booster pump 110 and the pressure at the inlet of the rear booster pump 110 are maintained between 16 and 10.32MPa, and that the pressure of the long-distance piping system 10 is pressurized again to 10.32MPa as much as possible, thereby reducing the number of booster pumps 110 to save costs.
Specifically, n-1 pipeline system booster pumps 110 are arranged on the pipeline 100, so that the pipeline 100 is divided into n sections, and the length of the pipeline in the ith section is x i (i=1, 2 … n), i.e., the length between the i-th line system booster pump 110 and the i-1-th line system booster pump 110 is x i (i=1, 2 … n). And, the pressure at the inlet of each of the pipeline system booster pumps 110 is 10.32MPa, and the pressure at the outlet of each of the pipeline system booster pumps 110 is 15 to 18MPa.
The arrangement position of the n-1 line system booster pumps 110 is obtained by the following pressure drop gradient formula:
wherein H is L For the liquid content of the cross section,is of liquid density, kg/m 3 ；/>Is a gasDensity of kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the θ is the angle of inclination of the pipe, rad; omega is the gas-liquid mixing speed, m/s; g is the mass flow of the liquid-gas mixture, kg/s; d is the inner diameter of the pipeline, m; omega sg Is the gas phase conversion speed, m/s; p is the average absolute pressure of the dl section pipeline and Pa; lambda is the liquid-gas mixing friction coefficient.
It will be appreciated that referring to FIG. 5, the x-th pipeline 100 can be obtained by the pressure drop gradient equation i Distance-pressure equation of (i=1, 2 … n), and x is obtained from the distance-pressure equation i The length value of (i=1, 2 … n) ultimately determines the arrangement position of the i-th piping system booster pump 110.
The pressure drop gradient formula of the present embodiment, taking into account the elevation change of the long-distance pipeline, introduces the parameter θ, it will be appreciated that the pipeline 100 is illustrated as horizontal in fig. 2-4 for ease of illustration only, x i (i=1, 2 … n) is understood to be the length of the conduit between two booster pumps 110, rather than the linear distance between two booster pumps 110.
The pressure drop gradient formula of the embodiment fully considers the CO 2 The gas from the gas source mixes with small amounts of CH4 and N2 gases. It will be appreciated that CO 2 Under the temperature and pressure conditions in the supercritical state, CH4 and N2 are in the gaseous state.
For this purpose, the present embodiment introduces: cross-sectional liquid content, gas density, gas-liquid mixing speed, liquid-gas mixing mass flow, gas phase conversion speed, and liquid-gas mixing friction coefficient for supercritical CO mixed with small amounts of CH4 and N2 gases 2 Long distance pipeline transportation, a calculation model is more accurate, so that the position of each pipeline system booster pump 110 can be accurately arranged.
In the present embodiment, the liquid-gas mixture friction coefficient λ=kλ 0 e n 。
Wherein k is a correction coefficient, lambda 0 Is the hydrodynamic friction coefficient of uniform flow.
Establishing an optimization model to solve k:
Find k
wherein Δp is the actual pressure drop; Δp (k) is defined as λ=kλ 0 e n Calculating the theoretical pressure drop after the hydraulic friction coefficient; n is the number of conduit pressure drop samples; f (k) is the sum of the square deviation of the actual pressure drop and the theoretical pressure drop.
By the above arrangement, the pressure drop gradient calculation model of the present embodiment is modified, so that the calculation error of the distance-pressure equation in the ith (i=1, 2 … n) section is reduced, that is, x between the ith pipeline system booster pump 110 and the ith-1 pipeline system booster pump 110 is reduced i The distance-pressure equation calculation error of the length of (i=1, 2 … n) further accurately arranges the positions of n-1 pipeline system booster pumps 110 so as to meet engineering requirements.
In the present embodiment, in order to more accurately control the pressure of the long-distance pipeline system 10, a plurality of pressure sensors 120 are provided on the pipeline 100.
Specifically, a pressure sensor 120 is disposed at the inlet and outlet of the long-distance piping system 10, respectively. The pressure sensor 120 at the inlet of the pipeline system 10 is used for detecting whether the front pressurization of the long-distance pipeline system 10 is in place, and the pressure sensor 120 at the outlet of the pipeline system 10 is used for detecting whether the pressure at the outlet accords with the follow-up device of the pipeline system 10.
And, a pressure sensor 120 is also provided at the outlet of the n-1 pipeline system booster pumps 110, respectively, so as to detect whether the boost pressure of the pipeline system booster pumps 110 is in place.
Wherein, the inlets of the n-1 pipeline system booster pumps 110 are respectively provided with a pressure sensor 120 to detect the pressure at the inlet of the pipeline system booster pumps 110, and:
if it isThe ith pipeline system booster pump 110 is operated normally according to the calculated value;
if it isThe pressurizing time period of the i-th line system booster pump 110 is appropriately prolonged according to the measured value of the pressure sensor 120 at the inlet of the i-th line system booster pump 110.
Wherein p is (i,1) A calculated value for the pressure at the inlet of the i-th tubing booster pump 110;is the actual measurement of the pressure sensor 120 at the inlet of the i-th tubing booster pump 110; epsilon 1 To determine whether the threshold value of the i-th piping system booster pump 110 boosting period needs to be adjusted.
Thus, the pressure sensor 120 arranged at the inlet of the booster pump 110 of the pipeline system prevents the pressure in the pipeline following the booster pump 110 of the ith pipeline system from being lower than 10.32MPa due to the pressure drop accumulation effect.
It will be appreciated that ifIt is also possible that x i Leakage occurs in the length of the pipeline, so that the pressure at the inlet of the i-th pipeline system booster pump 110 is suddenly changed, and the pressure suddenly changed is transmitted to the outlet of the i-1-th pipeline system booster pump 110.
Therefore, in the present embodiment, ifAnd->Then indicate x i Leakage occurs in the length of tubing.
Wherein p is (i-1,2) A calculated value for the pressure at the outlet of the i-1 th tubing booster pump 110;is the actual measurement value of the pressure sensor 120 at the outlet of the i-1 th pipeline system booster pump 110; epsilon 2 Epsilon 3 To determine x i A threshold for whether a leak occurs in a length of tubing.
It will be appreciated that when x i When the pipeline with the length section leaks, x is needed to be found i The leakage point of the pipeline with the length section is convenient for taking measures rapidly, and the loss is reduced.
In the present embodiment, x i The leakage point of the pipeline of the length section is obtained by the pressure drop gradient formula.
Specifically, first, the actual measurement value of the pressure sensor 120 at the outlet of the booster pump 110 through the i-1 th piping systemObtaining x by using pressure drop gradient formula i A forward curve S1 of the pipeline of the length section;
second, the actual measurement value of the pressure sensor 120 at the inlet of the booster pump 110 through the ith piping systemObtaining x by using pressure drop gradient formula i A reverse curve S2 of the pipeline of the length section;
finally, the intersection point of the forward curve S1 and the reverse curve S2 is x i Leakage points of the length of pipeline.
Referring to fig. 5, embodiment x i The principle of determining the leakage point of the pipeline of the length section is as follows: under the condition that the pipeline is not leaked, the normal curve obtained by using the pressure drop gradient formula is S0; when the pipeline leaks and is stabilized again, the pipeline is utilizedTo the forward curve S1, with +.>To the inverse curve S2. The pressure before and after the leakage point has the same boundary condition and pressure value at the leakage point, so the intersection point of the forward curve S1 and the reverse curve S2 is x i Leakage points of the length of pipeline.
Thus, the present embodimentThe pressure drop gradient formula provided by the formula not only can accurately determine the arrangement position of the ith pipeline system booster pump 110, but also can accurately determine x i The leakage position of the pipeline of the length section has high engineering application value.
The embodiment also provides a phase control method for long-distance conveying of the supercritical carbon dioxide pipeline, which comprises the following steps:
step 1, increasing the pressure at the inlet of a long-distance pipeline system 10 to 15-18 MPa through a carbon dioxide compressor 1 and a booster pump 3 in front of the pipeline system;
step 2, determining the arrangement positions and the number of the pipeline system booster pumps 110 according to a pressure drop gradient formula, so that the pressure at the inlet of each pipeline system booster pump 110 is 10.32MPa;
wherein, the pressure drop gradient formula is:
wherein H is L For the liquid content of the cross section,is of liquid density, kg/m 3 ；/>Is of gas density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the θ is the angle of inclination of the pipe, rad; omega is the gas-liquid mixing speed, m/s; g is the mass flow of the liquid-gas mixture, kg/s; d is the inner diameter of the pipeline, m; omega sg Is the gas phase conversion speed, m/s; p is the average absolute pressure of the dl section pipeline and Pa; lambda is the liquid-gas mixed friction coefficient;
step 3, the long-distance pipeline system 10 is controlled by the pressure sensor 120 at the inlet and outlet of each pipeline system booster pump 110:
if it isThe ith pipeline system booster pump 110 is operated normally according to the calculated value;
if it isThe pressurizing time period of the i-th line system booster pump 110 is appropriately prolonged according to the measured value of the pressure sensor 120 at the inlet of the i-th line system booster pump 110;
if it isAnd->The pressure drop gradient formula is used to determine the location of the leak.
Wherein p is (i,1) A calculated value for the pressure at the inlet of the i-th tubing booster pump 110;is the actual measurement of the pressure sensor 120 at the inlet of the i-th tubing booster pump 110; p is p (i-1,2) A calculated value for the pressure at the outlet of the i-1 th tubing booster pump 110; />Is the actual measurement value of the pressure sensor 120 at the outlet of the i-1 th pipeline system booster pump 110; epsilon 1 To determine whether a threshold value of the pressurizing time period of the i-th pipeline system booster pump 110 needs to be adjusted; epsilon 2 Epsilon 3 To determine x i A threshold for whether a leak occurs in a length of tubing.
In this embodiment, step 3 includes:
step 31, passing the actual measurement value of the pressure sensor 120 at the outlet of the i-1 th pipeline system booster pump 110Obtaining x by using pressure drop gradient formula i A forward curve S1 of the pipeline of the length section;
step 32, passing the actual measurement value of the pressure sensor 120 at the inlet of the i-th pipeline system booster pump 110Obtaining x by using pressure drop gradient formula i A reverse curve S2 of the pipeline of the length section;
step 33, the intersection point of the forward curve S1 and the reverse curve S2 is x i Leakage points of the length of pipeline.
In the present embodiment, the liquid-gas mixture friction coefficient λ=kλ 0 e n 。
Wherein k is a correction coefficient, lambda 0 Is the hydrodynamic friction coefficient of uniform flow.
Establishing an optimization model to solve k:
Find k
wherein Δp is the actual pressure drop; Δp (k) is defined as λ=kλ 0 e n Calculating the theoretical pressure drop after the hydraulic friction coefficient; n is the number of conduit pressure drop samples; f (k) is the sum of the square deviation of the actual pressure drop and the theoretical pressure drop.
The foregoing is illustrative of the best mode of carrying out the invention, and is not presented in any detail as is known to those of ordinary skill in the art. The protection scope of the invention is defined by the claims, and any equivalent transformation based on the technical teaching of the invention is also within the protection scope of the invention.
Claims (5)
1. A supercritical carbon dioxide pipeline long-distance conveying phase control system comprises a long-distance pipeline system (10), wherein an inlet of the long-distance pipeline system is connected with a front supercharging device of the pipeline system, and an outlet of the long-distance pipeline system is connected with an injection well;
the long-distance pipeline system (10) comprises a pipeline (100) and a plurality of pipeline system booster pumps (110) arranged on the pipeline (100), wherein the pressure at the inlet of each pipeline system booster pump (110) is configured to be 10.32MPa;
a pressure sensor (120) is respectively arranged at the inlet and the outlet of each pipeline system booster pump (110);
the system is characterized in that the arrangement position of each pipeline system booster pump (110) is obtained by a pressure drop gradient formula;
wherein if itThe ith pipeline system booster pump (110) can normally operate according to the calculated value of the pressure drop gradient formula;
if it isThen the pressurizing time period of the i-th pipeline system booster pump (110) is prolonged appropriately according to the measured value of the pressure sensor (120) at the inlet of the i-th pipeline system booster pump (110);
if it isAnd->Judging that the pipeline (100) leaks, and determining the position of a leakage point by using the pressure drop gradient formula;
wherein n-1 is the number of the pipeline system booster pumps (110);
p (i,1) calculating a pressure at an inlet of an ith tubing system booster pump (110);is the actual measurement value of the pressure sensor (120) at the inlet of the i-th pipeline system booster pump (110); p is p (i-1,2) Calculating a pressure at an outlet of an i-1 th tubing booster pump (110); />Is the pressure at the outlet of the i-1 th pipeline system booster pump (110)An actual measurement value of the sensor (120);
ε 1 to determine whether a threshold value of a boost duration of the ith piping system booster pump (110) needs to be adjusted; epsilon 2 Epsilon 3 To determine x between the ith line system booster pump (110) and the (i-1) th line system booster pump (110) i A threshold value for whether a leak occurs in the length of tubing (100);
the pressure drop gradient formula is:
wherein H is L For the liquid content of the cross section,is of liquid density, kg/m 3 ；/>Is of gas density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the θ is the angle of inclination of the pipe, rad; omega is the gas-liquid mixing speed, m/s; g is the mass flow of the liquid-gas mixture, kg/s; d is the inner diameter of the pipeline, m; omega sg Is the gas phase conversion speed, m/s; p is the average absolute pressure of the dl section pipeline and Pa; lambda is the liquid-gas mixed friction coefficient;
if it is determined that the pipeline has leakage, x i Leakage occurs in the length of tubing (100);
wherein x is i The leak point of the length of tubing (100) is obtained from the pressure drop gradient equation:
through the actual measurement value of the pressure sensor (120) at the outlet of the i-1 th pipeline system booster pump (110)Obtaining x of the pipeline (100) by using the pressure drop gradient formula i A forward curve S1 of the length segment;
pressure sensing at the inlet of booster pump (110) through the ith piping systemActual measurement value of device (120)Obtaining x of the pipeline (100) by using the pressure drop gradient formula i A reverse curve S2 of the length segment;
the intersection point of the forward curve S1 and the reverse curve S2 is the x of the pipeline (100) i Leakage points of the length sections.
2. The system of claim 1, wherein: the liquid-gas mixing friction coefficient is as follows:
λ＝kλ 0 e n
wherein k is a correction coefficient, lambda 0 A hydrodynamic friction coefficient for uniform flow;
wherein, establishing an optimization model to solve k:
Find k
Min
wherein Δp is the actual pressure drop; Δp (k) is defined as λ=kλ 0 e n Calculating the theoretical pressure drop after the hydraulic friction coefficient; n is the number of conduit pressure drop samples; f (k) is the sum of the square deviation of the actual pressure drop and the theoretical pressure drop.
3. A method for controlling the long-distance conveying phase state of a supercritical carbon dioxide pipeline, which is used for the system as claimed in claim 1 or 2, and is characterized in that: the method comprises the following steps:
step 1, increasing the pressure at the inlet of a long-distance pipeline system (10) to 15-18 MPa through a carbon dioxide compressor (1) and a booster pump (3) in front of the pipeline system;
step 2, determining the arrangement positions and the number of the pipeline system booster pumps (110) according to a pressure drop gradient formula, so that the pressure at the inlet of each pipeline system booster pump (110) is 10.32MPa;
wherein, the pressure drop gradient formula is:
wherein H is L For the liquid content of the cross section,is of liquid density, kg/m 3 ；/>Is of gas density, kg/m 3 The method comprises the steps of carrying out a first treatment on the surface of the g is gravity acceleration m/s 2 The method comprises the steps of carrying out a first treatment on the surface of the θ is the angle of inclination of the pipe, rad; omega is the gas-liquid mixing speed, m/s; g is the mass flow of the liquid-gas mixture, kg/s; d is the inner diameter of the pipeline, m; omega sg Is the gas phase conversion speed, m/s; p is the average absolute pressure of the dl section pipeline and Pa; lambda is the liquid-gas mixed friction coefficient;
step 3, controlling the long-distance pipeline system (10) through pressure sensors (120) at the inlet and the outlet of each pipeline system booster pump (110):
if it isThe ith pipeline system booster pump (110) can normally operate according to the calculated value;
if it isThen the pressurizing time period of the i-th pipeline system booster pump (110) is prolonged appropriately according to the measured value of the pressure sensor (120) at the inlet of the i-th pipeline system booster pump (110);
if it isAnd->The pressure drop gradient formula is used to determine the location of the leak.
4. A method as claimed in claim 3, wherein: the step 3 comprises the following steps:
step 31, through the actual measurement value of the pressure sensor (120) at the outlet of the i-1 th pipeline system booster pump (110)Obtaining x of the pipeline (100) by using a pressure drop gradient formula i A forward curve S1 of the length segment;
step 32, through the actual measurement value of the pressure sensor (120) at the inlet of the ith pipeline system booster pump (110)Obtaining x of the pipeline (100) by using a pressure drop gradient formula i A reverse curve S2 of the length segment;
step 33, the intersection point of the forward curve S1 and the reverse curve S2 is the x of the pipeline (100) i Leakage points of the length sections.
5. A method as claimed in claim 3, wherein: the liquid-gas mixing friction coefficient is as follows:
λ＝kλ 0 e n
wherein k is a correction coefficient, lambda 0 A hydrodynamic friction coefficient for uniform flow;
wherein, establishing an optimization model to solve k:
Find k
Min
wherein Δp is the actual pressure drop; Δp (k) is defined as λ=kλ 0 e n Calculating the theoretical pressure drop after the hydraulic friction coefficient; n is the number of conduit pressure drop samples; f (k) is the sum of the square deviation of the actual pressure drop and the theoretical pressure drop.
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| CN105135216A (en) * | 2015-07-30 | 2015-12-09 | 云南大红山管道有限公司 | Method for locating leakage position of ore pulp conveying pipe |
| CN110513603A (en) * | 2019-08-13 | 2019-11-29 | 常州大学 | A kind of nonmetal pipeline leakage locating method based on inverse Transient Analysis |
| CN212480831U (en) * | 2020-04-21 | 2021-02-05 | 神华神东煤炭集团有限责任公司 | Liquid carbon dioxide long distance conveying system |
| CN114165725A (en) * | 2021-12-14 | 2022-03-11 | 中氢(湖南)氢能装备有限公司 | Supercritical working medium rapid filling and accurate supply device and method |
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| CN105135216A (en) * | 2015-07-30 | 2015-12-09 | 云南大红山管道有限公司 | Method for locating leakage position of ore pulp conveying pipe |
| CN110513603A (en) * | 2019-08-13 | 2019-11-29 | 常州大学 | A kind of nonmetal pipeline leakage locating method based on inverse Transient Analysis |
| CN212480831U (en) * | 2020-04-21 | 2021-02-05 | 神华神东煤炭集团有限责任公司 | Liquid carbon dioxide long distance conveying system |
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