Seawater pipeline electric heat tracing system, control method of seawater pipeline electric heat tracing system and seawater pipeline anti-icing and deicing method

Abstract

The invention provides a seawater pipeline electric heat tracing system, a control method of the seawater pipeline electric heat tracing system and a seawater pipeline anti-icing and deicing method. The seawater pipeline electric heat tracing system comprises a seawater pipeline; the plurality of electric tracing bands are circumferentially distributed on the pipeline section of the seawater pipeline; wherein the seawater pipeline is configured as follows: a first area and a second area are connected at two ends to form a complete pipeline section, and the hollow part of the pipeline section forms a fluid channel; the first area and the second area are divided by the middle horizontal plane of the fluid channel, and the first area is located on the upper side of the second area; moreover, the sum of the maximum heating powers of the electric tracing bands in the first area is greater than the sum of the maximum heating powers of the electric tracing bands in the second area.

Description

Technical Field

[0001] The present application relates to a seawater pipeline electric heating system and a control method thereof, and a seawater pipeline anti-icing and de-icing method. Background Art

[0002] The seawater piping system is a vital component of a ship. By bringing external seawater into the ship, it supplies water to systems such as cooling, firefighting, and household water. For example, it can be connected to the ship's engine cooling system to ensure the normal operation of these systems. When a ship is sailing in low-temperature environments (such as in polar waters), ice and flakes in the seawater, as well as seawater freezing inside the seawater pipes, can cause ice blockage, which can lead to failure of the seawater piping system and affect the normal operation of the ship.

[0003] Existing anti-icing / de-icing designs for seawater pipeline systems mainly include seawater filter gate solutions and hot water (or steam) pipeline heat exchange solutions. The seawater filter gate solution refers to the configuration of a filtering device at a location such as the seawater inlet to separate ice cubes from the seawater medium. However, this solution is limited by the filtration accuracy, and ice fragments and ice flocs are usually not completely filtered and enter the seawater pipeline. The hot water and steam pipeline heat exchange solution refers to the use of hot water or steam pipelines, such as coil heat exchangers, to transfer heat to structures such as storage bins to melt ice crystals. However, its ice melting capacity is limited, and seawater entering the pipeline is still in an unfavorable state of seawater-ice crystal two-phase flow. In addition, in low temperature environments, the seawater pipeline may refreeze and cause blockage. Therefore, the field needs to continue to develop anti-icing / de-icing designs that protect the seawater pipelines of seawater pipeline systems, especially to optimize the distribution of ice crystals in the seawater-ice crystal two-phase flow in the seawater pipeline to achieve reduced energy consumption and improved economic efficiency.

[0004] In view of this, the inventors of the present application propose a seawater pipeline electric heating system and a control method thereof, a seawater pipeline anti-icing and de-icing method, etc., to solve at least one or a combination of the above technical problems. Summary of the Invention

[0005] The purpose of this application is to provide a seawater pipeline electric heating system.

[0006] Another object of the present application is to provide a control method for a marine seawater pipeline electric heating system.

[0007] Another object of the present application is to provide a method for anti-icing and de-icing seawater pipelines of a marine seawater pipeline electric heating system.

[0008] According to the first aspect of the present application, a seawater pipeline electric heating system comprises: a seawater pipeline; a plurality of electric heating cables circumferentially distributed in a pipe cross-section of the seawater pipeline; wherein the seawater pipeline is configured such that a first region and a second region are connected at both ends to form a complete pipe cross-section, and a hollow portion of the pipe cross-section constitutes a fluid channel; the first region and the second region are divided by a middle horizontal plane of the fluid channel, and the first region is located above the second region; and the sum of the maximum heating powers of the electric heating cables located in the first region is greater than the sum of the maximum heating powers of the electric heating cables located in the second region.

[0009] The principle of the above technical solution to achieve the advanced technical effect is that the arrangement of electric heating tape in the seawater pipeline can achieve the insulation and anti-freezing of the pipeline, thereby avoiding the ice blockage problem of the pipeline and improving the reliability and safety of the seawater pipeline system and ship operation; Figure 5 As shown, according to the flow state of the seawater-ice crystal two-phase flow in the seawater pipeline, ice crystal particles and the like are more distributed in the upper area in the seawater medium. Therefore, the electric heating tape is arranged in different areas, so that the electric heating tape can output a greater heating power in the first area of the seawater pipeline than in the second area, which is beneficial to avoid excessive heating of the seawater medium and enable heat to be efficiently transferred to the ice crystal particles and the like, thereby improving the heating efficiency of the system and reducing energy consumption. The overall structure is streamlined and occupies a small space, which is beneficial to achieve compact spatial layout of the pipeline.

[0010] In one or more embodiments of the seawater pipeline electric heating system, the sum of the maximum heating powers of all the electric heating cables is greater than or equal to the total required power; the total required power includes a first required power and a second required power; the first required power is equal to the heat dissipation loss of the seawater pipeline; the second required power is determined based on the heating requirement to melt at least part of the ice crystal particles.

[0011] The power configuration of traditional pipeline electric heating systems only considers compensating for the heat loss of the pipeline. However, the heating power configuration of the seawater pipeline electric heating system is not only sufficient to compensate for the heat loss of the pipeline, but also to meet the heating needs of melting ice crystals. This allows the system to not only insulate and prevent freezing of the pipeline, but also melt ice inside the pipeline.

[0012] In one or more embodiments of the seawater pipeline electric heating system, the total required power satisfies the relationship:

[0013] P min =Q1+Q2

[0014] Where, P min is the total required power; Q1 is the first required power; Q2 is the second required power; the second required power satisfies the relationship:

[0015]

[0016] Where d is the diameter of the seawater pipe; v is the velocity of the seawater medium; ρ i represents ice crystal density; IPF represents ice crystal volume fraction; C p represents the specific heat capacity of ice crystals; T p Indicates the target temperature of electric heating; T f Indicates the ice crystal reference temperature; l indicates the heating length of the electric heating tape.

[0017] In one or more embodiments of the seawater pipeline electric heating system, the number of the electric heating cables satisfies the relationship:

[0018] N≥(1+j)·P min / P0

[0019] Where, N represents the number of electric heating cables; j represents the safety margin coefficient; P min represents the total required power; P0 represents the maximum heating power of a single electric heating tape.

[0020] In one or more embodiments of the seawater pipeline electric heating system, a polar coordinate system is established with the center of the pipe cross section as the pole and the axis pointing upward in the vertical direction as the polar axis; in the polar coordinate system, the angular coordinate of the electric heating tape is expressed as θ, in rad, and the angular coordinate of the nth electric heating tape is denoted as θ(n), where n=1,…,N, and satisfies the relationship:

[0021]

[0022] in,

[0023]

[0024] Where θ0 represents the reference angle of the electric heating tape position; k represents the density parameter of the electric heating tape, which is greater than 1; N represents the number of electric heating tapes, which is an even number greater than or equal to 2.

[0025] In one or more embodiments of the seawater pipeline electric heating system, the seawater pipeline electric heating system further includes: a temperature measuring unit, used to obtain the temperature value of the seawater in the seawater pipeline and output it to the power control unit; an ice crystal integral fraction measuring unit, used to obtain the IPF value of the seawater in the seawater pipeline and output it to the power control unit; a power control unit, used to control the heating power output by each of the electric heating cables based on information obtained from the temperature measuring unit and the ice crystal integral fraction measuring unit.

[0026] A control method for a marine seawater pipeline electric tracing heating system according to the second aspect of the present application, wherein the seawater pipeline electric tracing heating system is the seawater pipeline electric tracing heating system described in any one of the above embodiments; the control method includes:

[0027] Controlling the heating power output by each electric tracing belt according to the temperature value and IPF value of the seawater in the seawater pipeline.

[0028] In one or more embodiments of the control method, the seawater pipeline has a first end and a second end, and seawater flows from the first end to the second end, and the electric tracing belts are arranged between the first end and the second end; the seawater pipeline electric tracing heating system has a first mode and a second mode; in the first mode, each electric tracing belt outputs the maximum heating power; in the second mode, the heating power output by each electric tracing belt is determined according to the IPF value in the seawater pipeline; the control method includes repeatedly performing the following steps:

[0029] S101. Determine whether the temperature value T at the first end reaches a preset temperature threshold Ts; if T≥Ts, skip step S102; if T<Ts, execute step S102;

[0030] S102. Determine whether the IPF value at the second end reaches a preset ice crystal volume fraction threshold IPFs; if IPF≥IPFs, operate in the first mode; if IPF<IPFs, operate in the second mode.

[0031] An anti-icing and de-icing method for a marine seawater pipeline according to the third aspect of the present application, characterized by including:

[0032] Circumferentially arranging a plurality of electric tracing belts on the cross-section of the seawater pipeline;

[0033] The electric tracing belt outputs heat to melt the ice crystals in the seawater pipeline; wherein,

[0034] The seawater pipeline is configured such that a first region and a second region are connected at both ends to form a complete cross-section of the pipeline, and the hollow part of the cross-section of the pipeline forms a fluid channel; the first region and the second region are divided by the middle horizontal plane of the fluid channel, and the first region is located above the second region; and the sum of the maximum heating powers of the electric tracing belts in the first region is greater than the sum of the maximum heating powers of the electric tracing belts in the second region.

[0035] In one or more embodiments of the seawater pipeline anti-icing and de-icing method, the anti-icing and de-icing method further includes:

[0036] Obtaining the total required power of the seawater pipeline electric tracing heating system;

[0037] According to the total required power, the number of electric heating cables is obtained;

[0038] According to the number of the electric heating cables, the distribution position of each electric heating cable is obtained, so that the number of the electric heating cables in the first area is greater than the number of the electric heating cables in the second area. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The above and other features, properties and advantages of the present application will become more apparent through the following description in conjunction with the accompanying drawings and embodiments. In the accompanying drawings, the same reference numerals always represent the same features. It should be noted that these drawings are only for illustration and are not drawn to scale. They should not be used to limit the actual scope of protection claimed in this application. Among them:

[0040] Figure 1 This is a schematic structural diagram of a seawater pipeline according to an embodiment of the present application;

[0041] Figure 2 This is a schematic structural diagram of a seawater pipeline electric heating system according to an embodiment of the present application;

[0042] Figure 3 This is a schematic structural diagram of a seawater pipeline electric heating system according to an embodiment of the present application;

[0043] Figure 4 This is a schematic structural diagram of a seawater pipeline electric heating system according to an embodiment of the present application;

[0044] Figure 5 Schematic diagram of the distribution of ice crystal particles in the seawater-ice crystal two-phase flow in the seawater pipeline.

[0045] Figure 6 Schematic diagram of a control method according to an embodiment of the present application.

[0046] Figure 7 Schematic diagram of a flow chart of a method for anti-icing and de-icing seawater pipelines according to an embodiment of the present application.

[0047] Figure 8 Schematic diagram of a control method according to an embodiment of the present application.

[0048] Figure 9 This is a schematic structural diagram of a control system according to an embodiment of the present application.

[0049] Reference numerals:

[0050] 1. Seawater pipeline electric heating system; 10. Seawater pipeline; 11. First area; 12. Second area; 13. First layer; 14. Second layer; 15. First end; 16. Second end; 17. Fluid channel; 20. Electric heating cable;

[0051] 30. Control system; 31. Memory; 32. Processor. DETAILED DESCRIPTION

[0052] Each embodiment of the present application will now be described in detail, and examples of these embodiments are shown in the accompanying drawings and are described below. Although the application will be described in conjunction with the exemplary embodiments, it should be appreciated that the application is not intended to be limited to those exemplary embodiments. On the contrary, the application is intended to cover not only these exemplary embodiments, but also various alternative forms, modifications, equivalent forms, and other embodiments that may be included within the spirit and scope of the application as defined by the appended claims.

[0053] This application uses specific terms to describe the embodiments of this application. For example, "one embodiment" and / or "an embodiment" refers to a feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" mentioned twice or multiple times in different places in this application does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0054] In this application, the terms "first", "second", etc. are only used to distinguish descriptions and should not be understood as indicating or implying positional relationships or importance rankings.

[0055] In the subsequent description, unless otherwise expressly specified or limited, the orientations or positional relationships indicated by “up,” “down,” “left,” “right,” “front,” “back,” or other directional terms are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and / or be implemented in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0056] In the following description, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc. should be understood in a broad sense; for example, they can refer to fixed connections or movable connections; they can refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on specific circumstances.

[0057] This application uses flowcharts to illustrate the operations performed by the systems and methods according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0058] It can be understood that the seawater pipeline electric heating system provided in the present application is particularly suitable for being configured to be connected to the diesel engine cooling system of a polar ship, but is not limited to this; it can also be used in other applicable occasions where seawater pipelines need to be protected against / de-icing, such as being configured on other types of ships, or connected to other systems of the ship.

[0059] See also Figures 1 to 5 The seawater pipeline electric heating system 1 shown in the figure comprises: a seawater pipeline 10; a plurality of electric heating cables 20 circumferentially distributed in the pipe cross section of the seawater pipeline 10; wherein the seawater pipeline 10 is configured such that a first region 11 and a second region 12 are connected at both ends to form a complete pipe cross section, and the hollow portion of the pipe cross section forms a fluid channel 17; the first region 11 and the second region 12 are separated by the middle horizontal plane of the fluid channel 17 ( Figure 1 The first area 11 is located above the second area 12, and the total maximum heating power of the electric trace heating tape 20 located in the first area 11 is greater than the total maximum heating power of the electric trace heating tape 20 located in the second area 12. The electric trace heating tape mentioned here refers to a strip-shaped electric heating element generally composed of a conductor, a heating material, and an insulating layer, which heats the heating material by conducting electricity through the conductor to provide heat to the pipeline, etc. The middle horizontal plane of the fluid channel refers to the fluid channel 17 in the direction of gravity ( Figure 1 The median position in the direction Z) shown, that is, the middle height position, is a horizontal plane, the height z1 of the first area 11 and the height z2 of the second area 12 are equal. For example, when the fluid channel is circular, the middle horizontal plane is a horizontal plane passing through the center of the circle. The maximum heating power of the electric heating tape refers to the maximum heating power that each of the electric heating tapes 20 can output. When a ship is sailing in an extremely low temperature environment, the seawater is in a flow state of seawater-ice crystal two-phase flow, which contains seawater medium and ice crystals; the seawater medium mentioned here refers to the liquid phase in the solid-liquid two-phase flow; ice crystals refer to the solid phase in the solid-liquid two-phase flow, which can be independent, dispersed ice crystal particles, or ice flocs, ice cubes, etc. formed by the aggregation of multiple ice crystal particles.

[0060] Arranging the electric heating cable 20 in the seawater pipeline 10 can achieve heat preservation and antifreeze of the pipeline, thereby avoiding ice blockage of the pipeline and improving the reliability and safety of the seawater pipeline system and the operation of the ship; Figure 5As shown, the configuration is optimized according to the flow state of the seawater-ice crystal two-phase flow in the ship's seawater pipeline. Since ice crystal particles and the like are more distributed in the upper area in the seawater medium, the electric heating tape is arranged in different areas, so that the electric heating tape can output a greater heating power in the first area of the seawater pipeline than in the second area, which is beneficial to avoid excessive heating of the seawater medium and efficiently conduct heat to the ice crystal particles and the like, thereby improving the heating efficiency of the system, reducing energy consumption, and improving economy. In addition, the use of electric heating tape is also beneficial to precise control of the output heat, and is easy to install and maintain. The overall structure is streamlined and occupies less space, which is beneficial to achieve compact spatial layout of the pipeline.

[0061] like Figure 2 、 Figure 3 As shown, optionally, the pipeline has a first layer 13 and a second layer 14; the first layer 13 forms the fluid channel 17, allowing the fluid to flow therein; the plurality of electric heating cables 20 are arranged on the outer peripheral side of the first layer 13, that is, outside the fluid channel 17, to reduce the impact on the flow resistance of seawater; the second layer 14 (insulation layer) covers the first layer 13 and the plurality of electric heating cables 20 for insulation; the second layer 14 can also be configured to be made of polyurethane (PU) foam material.

[0062] Optionally, the seawater pipeline 10 is connected to a marine engine cooling system; specifically, it can be configured to be connected to a heat exchanger of the cooling system, so that the heat generated by the engine is absorbed and carried away by seawater flowing through the seawater pipeline 10 through the heat exchanger, thereby cooling the engine.

[0063] Optionally, the seawater pipeline 10 is a seawater pipeline 10 of a polar ship, and the polar ship refers to a ship suitable for sailing in polar waters.

[0064] In one or more embodiments of the seawater pipeline electric heating system 1, the sum of the maximum heating powers of all the electric heating cables 20 is greater than or equal to the total required power; the total required power includes a first required power and a second required power; the first required power is equal to the heat loss of the seawater pipeline 10; the second required power is determined based on the heating requirement to melt at least part of the ice crystals, so that at least part of the ice crystals in the pipeline can melt.

[0065] Existing electric heating systems for pipelines are generally used for insulation and antifreeze of homogeneous fluid transportation pipelines in fields such as petrochemicals, so their heating power is generally configured to only compensate for the heat loss of the pipeline; and for the seawater pipeline 10 of a ship, especially the seawater pipeline 10 of a ship operating in an extremely low temperature environment, the seawater pipeline electric heating system 1 is configured so that the maximum heating power that can be output as a whole is greater than or equal to the total required power, and the total required power includes not only the first power but also the second power. In other words, the maximum heating power that can be output as a whole by the system can not only compensate for the heat loss of the pipeline, but also meet the heating requirements for melting ice inside the pipeline, so as to achieve insulation, antifreeze and de-icing of the pipeline, and further improve the reliability and safety of the seawater pipeline system and ship operation.

[0066] Specifically, the seawater pipeline electric heating system 1 described herein can be configured so that after seawater under preset operating conditions is heated by the seawater pipeline electric heating system 1, ice crystals therein are expected to melt; for example, such melting can be characterized as an expected reduction in the ice packing factor (IPF); the ice packing factor described herein can be a volumetric ice packing factor, or an ice crystal volume fraction, which refers to the ratio of the volume of ice crystals to the total volume of the solid-liquid two-phase flow; since the total power demand includes the first power demand and the second power demand, the maximum heating power that the system can output as a whole can be significantly greater than the first power demand to meet the heating demand for melting at least part of the ice crystals; further, to ensure that at least part of the ice crystals are melted, the system can also be configured so that the actual ice crystal content of the seawater inside the seawater pipeline 10 is obtained to determine whether the expected goal of ice melting has been achieved; further, the electric heating system can also be configured to control the heating according to the actual ice crystal content of the seawater so that the actual ice crystal content changes toward the expected target.

[0067] In one or more embodiments of the pipeline electric heating system 1, the total required power and the second required power are calculated; the change in the preset ice crystal integral fraction (IPF value) is used as the expected de-icing target. Since the actual ice crystal integral fraction of seawater can be measured by an electromagnetic wave test method using a spectrum analyzer or an acoustic test method using an ultrasonic sensor, the de-icing effect is easy to measure.

[0068] Optionally, the total required power satisfies the relationship:

[0069] P min =Q1+Q2

[0070] Where, P minrepresents the total required power; Q1 represents the first required power; Q2 represents the second required power; the total required power P min The first required power Q1 and the second required power Q2 can be expressed as the power required per unit length of the seawater pipeline 10, in W / m.

[0071] Optionally, the second required power satisfies the relationship:

[0072]

[0073] Where d is the diameter of the seawater pipe, in meters; v is the flow velocity of the seawater medium (liquid), in meters per second; ρ i represents ice crystal density, in kg / m3; IPF represents ice crystal volume fraction, dimensionless; C p represents the specific heat capacity of ice crystals, with the unit being J / (kg·K); T p Indicates the target temperature of electric heating, in K; T f Indicates the ice crystal reference temperature in K; l indicates the heating length of the electric heating tape in m; the electric heating target temperature mentioned here refers to the temperature that the seawater medium inside the seawater pipeline 10 is expected to reach through the heating of the electric heating tape 20; optionally, the electric heating target temperature is preset in the range of 275.15K to 277.15K to ensure that the ice crystals are fully melted; the seawater medium flow rate, ice crystal density, ice crystal integral fraction, ice crystal reference temperature, etc. mentioned here refer to the threshold values of the relevant parameters inside the seawater pipeline 10 determined according to the preset operating conditions, which are affected by factors such as different sea areas (such as the polar waters of the Antarctic or the Arctic) and seasons. There are differences in salinity, and thus there are differences in the thermodynamic parameters of ice crystals, and the temperature of ice crystals entering the seawater pipe 10 varies within a small range; optionally, taking the phase change critical temperature of seawater with a salinity of 35‰ as a reference, the preset ice crystal reference temperature is approximately 271.28K; the heating length of the electric heating tape refers to the length of the seawater pipe 10 heated by the electric heating tape 20; taking into account the output power attenuation of the electric heating tape at the end, and the influence of factors such as the laying method, for example, the electric heating tape also has bends and joints, the length of the electric heating tape 20 can be greater than the length of the heated seawater pipe 10, that is, greater than the heating length of the electric heating tape.

[0074] Optionally, the first required power is determined according to the heat exchange between the insulation layer (second layer) and the outside air, satisfying the relationship:

[0075]

[0076] Where λ represents the thermal conductivity of the insulation material, in W / (m·K); T p It represents the target temperature of electric heating, in K; Te represents the external ambient temperature, in K; d represents the pipe diameter, in m; δ represents the thickness of the insulation layer, in m; α represents the heat transfer coefficient between the insulation layer and the outside air, in W / (m2·K).

[0077] Optionally, in one or more embodiments of the pipeline electric heating system 1, the number of the electric heating cables 20 satisfies the relationship:

[0078] N≥(1+j)·P min / P0

[0079] Where, N represents the number of electric heating cables; j represents the safety margin coefficient; P min represents the total power demand; P0 represents the maximum heating power of a single heating cable. Specifically, the maximum heating power P0 of a single heating cable 20 can be set to the nominal maximum heating power of the cable. The safety margin factor j can be set within a range of 10% to 20%, for example, 15%. This ensures that a sufficient number of heating cables 20 are available to meet the heating requirements for pipeline antifreeze and ice melting. Furthermore, the introduction of the safety margin factor enhances the system's ability to cope with extreme operating conditions and improves system reliability.

[0080] In one or more embodiments of the pipeline electric heating system 1, a polar coordinate system is established with the center of the cross-section of the seawater pipeline 10 as the pole and an axis pointing vertically upward, in the direction opposite to the direction of gravity, as the polar axis. Because the plurality of electric heating cables 20 are circumferentially distributed within the seawater pipeline 10, the angular coordinates in the polar coordinate system can represent their arrangement. In the polar coordinate system, the angular coordinate of the electric heating cables 20 is represented by θ, in rad. The angular coordinate of the nth electric heating cable 20 is denoted by θ(n), where n = 1, ..., N, and satisfies the relationship:

[0081]

[0082] in,

[0083]

[0084] Wherein, θ0 represents the reference angle of the electric heating tape position, and the unit is rad; k represents the electric heating tape density parameter, which is dimensionless and has a value greater than 1; N represents the number of electric heating tapes, and has a value greater than or equal to an even number of 2; optionally, the electric heating tape density parameter k can be set within the range of 1 to 2 according to actual conditions.

[0085] The angular coordinate θ(1) of the first electric heating tape 20 is 0 rad, that is, it is located directly above in the vertical direction; starting from the first electric heating tape 20, the positions of the remaining electric heating tapes 20 are calculated in sequence; further, each of the electric heating tapes can also be arranged in a straight line along the extension direction of the seawater pipeline 10; thus, a layout form with proportional changes in density is provided, which is convenient for design, installation, etc. and has strong practicality.

[0086] like Figure 4 As shown, in one or more embodiments of the pipeline electric heating system 1, the pipeline electric heating system 1 also includes: a temperature measuring unit, used to obtain the temperature value of the seawater in the seawater pipeline 10, and output it to the power control unit; an ice crystal integral fraction measuring unit, used to obtain the ice crystal integral fraction (IPF value) of the seawater in the seawater pipeline 10, and output it to the power control unit; a power control unit, communicatively connected to the temperature measuring unit, the ice crystal integral fraction measuring unit, and the plurality of electric heating cables 20, for controlling the heating power output by each of the electric heating cables 20 according to the temperature value and the IPF value obtained from the temperature measuring unit and the ice crystal integral fraction measuring unit.

[0087] Specifically, the temperature measurement unit can adopt detection devices such as temperature sensors; the ice crystal integral fraction measurement unit can be configured to adopt a spectrum analyzer to measure through an electromagnetic wave test method, or adopt an ultrasonic sensor to measure through an acoustic test method, etc.; the power control unit can adopt a proportional integral differential controller (Proportion Integration Differentiation, PID controller); the system also includes a power supply, such as a DC power supply, for powering the power controller, etc.

[0088] Due to the high specific heat capacity of seawater, heat is absorbed by the liquid seawater medium, resulting in insignificant temperature changes. Compared with the comparative scheme that controls the heating power only according to temperature, the use of two parameter signals of temperature and IPF value for control is more conducive to improving control accuracy, reducing energy consumption, and facilitating intuitive detection of ice melting effects. In particular, for the seawater pipeline electric heating system 1 connected to the cooling system, excessive heating of seawater will lead to a decrease in the cooling efficiency of the cooling system. The use of two parameter signals of temperature and IPF value for heating control to improve control accuracy is more conducive to simultaneously meeting the comprehensive effects of pipeline antifreeze, ice melting, and ensuring the performance of the cooling system.

[0089] like Figure 3As shown, the seawater pipeline 10 is optionally configured to have a first end 15 and a second end 16. The first end 15 is the seawater inlet end of the pipeline electric heating system 1, and the second end 16 is the seawater outlet end of the pipeline electric heating system 1. Seawater flows from the first end 15 to the second end 16. The second end 16 can also be positioned in front of equipment such as pumps and valves to prevent seawater with excessive ice crystal content from entering the relevant equipment, causing damage to components and affecting their normal operation. Multiple electric heating cables 20 are arranged between the first end 15 and the second end 16. The temperature measurement unit is located at the first end 15, and the ice crystal fraction measurement unit is located at the second end 16. This design monitors the seawater temperature at the inlet end. If a certain safety threshold is reached, for example, if the seawater ice crystal content is confirmed to meet safety requirements at a certain seawater temperature, the output power can be reduced accordingly to save energy. The IPF value of the seawater at the outlet end is monitored, and the output power can be controlled accordingly to ensure ice melting.

[0090] like Figure 6 As shown, in one or more embodiments of the pipeline electric heating system 1, the pipeline electric heating system 1 has a first mode and a second mode; in the first mode, each of the electric heating cables 20 outputs the maximum heating power; in the second mode, the heating power output by each of the electric heating cables is determined according to the IPF value obtained by the ice crystal integral fraction measuring unit; optionally, the sum of the heating powers output by the electric heating cables 20 in the first area 11 is equal to the sum of the heating powers output by the electric heating cables 20 in the second area 12, so that the electric heating cables 20 heat the seawater pipeline 10 evenly in the first area 11 and the second area 12; the operating mode of the seawater pipeline electric heating system 1 is designed in this way, on the one hand, the first mode is configured to meet the maximum power demand and ensure system reliability; on the other hand, the second mode is configured to perform refined control according to specific working conditions, while meeting the pipeline antifreeze and ice melting requirements, reducing energy consumption.

[0091] like Figure 6As shown, the present application also provides a control method for a pipeline electric tracing heating system for ships. The pipeline electric tracing heating system is the seawater pipeline electric tracing heating system 1 described in the above embodiments. The pipeline electric tracing heating system 1 further includes: a temperature measurement unit for obtaining the temperature value of the seawater in the seawater pipeline 10 and outputting it to the power control unit; an ice crystal volume fraction measurement unit for obtaining the ice crystal volume fraction (IPF value) of the seawater in the seawater pipeline 10 and outputting it to the power control unit; a power control unit communicatively connected to the temperature measurement unit, the ice crystal volume fraction measurement unit, and the plurality of electric tracing tapes 20, for controlling the heating power output by each electric tracing tape 20 according to the temperature value and the IPF value obtained from the temperature measurement unit and the ice crystal volume fraction measurement unit. The control method includes:

[0092] S100. Control the heating power output by each electric tracing tape 20 according to the temperature value and IPF value of the seawater in the seawater pipeline 10. Specifically, the temperature value and IPF value of the seawater in the seawater pipeline 10 can be measured by the temperature measurement unit and the ice crystal volume fraction measurement unit.

[0093] Specifically, the pipeline electric tracing heating system 1 can be configured to have a first mode and a second mode. In the first mode, each electric tracing tape 20 outputs the maximum heating power. In the second mode, the heating power output by each electric tracing tape 20 is determined according to the IPF value obtained by the ice crystal volume fraction measurement unit, for example, determined according to the difference between the measured IPF and the preset ice crystal volume fraction threshold IPFs, and the sum of the heating powers output by the electric tracing tapes 20 in the first region 11 is equal to the sum of the heating powers output by the electric tracing tapes 20 in the second region 12. The control method includes: repeatedly performing the following steps:

[0094] S101. Determine whether the temperature value T at the first end 15 reaches the preset temperature threshold Ts. If T≥Ts, skip step S102. If T<Ts, perform step S102.

[0095] S102. Determine whether the IPF value at the second end 16 reaches the preset ice crystal volume fraction threshold. If IPF≥IPFs, run the first mode. If IPF<IPFs, run the second mode.

[0096] The preset temperature threshold Ts can take a value of 275.15(±2), unit: K; if T≥Ts, it is considered that the ice crystal content rate of the seawater is within the preset safe range, and step S102 is skipped; optionally, when T≥Ts, the electric tracing heating tape 20 outputs a lower (or zero) power for energy saving, but this is not limited thereto; if T<Ts, step S102 is executed. The preset ice crystal volume fraction threshold can be determined according to specific safety design requirements, for example, taking a value of 2%(±0.5%); if IPF≥IPFs, the ice crystal content rate is relatively high at this time, and the system outputs the maximum heating power to quickly de-ice, which is beneficial to improving the reliability of the seawater pipeline 10 system and the ship; if IPF<IPFs, it operates in the second mode, which is beneficial to achieving anti-icing / de-icing while saving energy consumption and meeting the comprehensive performance requirements.

[0097] Optionally, the control method further includes:

[0098] S103. After receiving the stop signal, the temperature measurement unit and the ice crystal volume fraction measurement unit stop measuring, and the electric tracing heating tape 20 stops heating, for example, configured to gradually reduce the heating power output by the electric tracing heating tape 20 until it becomes zero; the stop signal can be manually issued by a person, for example, after a person determines that the ship has left the extremely low temperature environment.

[0099] As Figure 7 shown, the present application also provides an anti-icing and de-icing method for a seawater pipeline, including:

[0100] S200. Arrange a plurality of electric tracing heating tapes 20 circumferentially on the seawater pipeline 10;

[0101] S201. The electric tracing heating tape 20 outputs heat to melt the ice crystals in the seawater pipeline 10; wherein,

[0102] The seawater pipeline 10 is configured such that the first region 11 and the second region 12 are connected at both ends to form the complete pipeline cross-section, and the hollow part of the pipeline cross-section forms the fluid channel 17; the first region 11 and the second region 12 are divided by the middle horizontal plane of the fluid channel 17, and the first region 11 is located above the second region 12; and, the sum of the maximum heating powers of the electric tracing heating tapes 20 located in the first region 11 is greater than the sum of the maximum heating powers of the electric tracing heating tapes 20 located in the second region 12.

[0103] Specifically, each of the electric heating cables 20 can be configured to be arranged roughly in a straight line along the extension direction of the seawater pipeline 10 to reduce the difficulty and cost of design, installation, and maintenance. In addition, adjustments need to be made accordingly based on the specific structural characteristics of the seawater pipeline 10, such as the cross-sectional shape of the pipeline changing, bending, or forming an angle with the horizontal plane, or having valves, flanges, etc., which are not repeated here.

[0104] In one or more embodiments of the anti-icing and de-icing method, step S200 specifically includes:

[0105] S202. Determine the total power requirement of the seawater pipeline electric heating system 1; the total power requirement can be calculated based on the relationship between the total power requirement described above, which will not be described in detail here;

[0106] S203. According to the total power demand, the number of the electric heating tape 20 is determined; the number of the electric heating tape 20 can be calculated based on the relationship between the number of electric heating tapes described above and will not be repeated here;

[0107] S204. Determine the distribution position of each of the electric heating tapes 20 based on the number of the electric heating tapes 20, so that the number of the electric heating tapes 20 in the first area 11 is greater than the number of the electric heating tapes 20 in the second area 12; the distribution position of each of the electric heating tapes 20 can be represented by its angular coordinates in polar coordinates, and is calculated based on the relationship satisfied by the above-mentioned electric heating tape angular coordinates, which will not be repeated here.

[0108] The present application also provides a control system 30 for a marine seawater pipeline electric heating system 1, which includes: a memory 31 for storing instructions that can be executed by a processor 32; a processor 32 for executing the instructions to implement the steps of the control method described in the above embodiment. Please refer to the above description for details, which will not be repeated here.

[0109] It should be noted that the aforementioned memory 31, processor 32, etc. are not limited to a specific memory or processor. For example, in some cases, both the memory and processor can have a distributed structure. For example, the memory and processor can be located on the electric heating system device and the backend cloud, respectively, with the electric heating system device and the backend cloud jointly implementing the aforementioned control method. Furthermore, in embodiments employing a distributed structure, the specific execution terminal of each step can be adjusted based on actual circumstances. The specific implementation of each step on a specific terminal should not limit the scope of protection of this application.

[0110] The present application also provides a computer-readable medium having a computer program thereon, which is executed by the processor 32 to implement the steps that can be implemented by the computer program in the control method or the seawater pipeline anti-icing and de-icing method as described in the above embodiments. Please refer to the above description for details, which will not be repeated here.

[0111] In addition, it is understandable that the computer-readable storage medium may also be in a system form, that is, including multiple computer-readable storage sub-media, so as to jointly implement the steps of the control method described above through multiple computer-readable storage media.

[0112] The present application also provides a computer program product, including a computer program. When the computer program is executed by the processor 32, it implements the control method described in the above embodiment or the steps of the seawater pipeline anti-icing and de-icing method that can be implemented by the computer program. Please refer to the above description for details, which will not be repeated here.

[0113] The present application also provides a ship, whose seawater pipeline system is equipped with the seawater pipeline electric heating system 1 to achieve anti-icing / de-icing of the seawater pipeline 10; optionally, the ship is a polar ship suitable for sailing in polar waters.

[0114] The following describes the seawater pipeline electric heating system 1, control method, and seawater pipeline anti-icing and de-icing method provided in the present application, taking the seawater pipeline electric heating system 1 connected to the diesel engine cooling system of a polar ship as an example, in order to more clearly illustrate the present application; since the relevant configuration can be adjusted according to specific design conditions and objectives, it should not be understood as limiting the scope of protection actually required by the present application.

[0115] The seawater pipe electric heating system 1 connected to the diesel engine cooling system of a polar ship as described above has a seawater pipe 10 configured as a horizontally arranged circular straight pipe with a length of 20m and a nominal diameter of 180mm. The heat output by the engine is absorbed by the seawater in the seawater pipe 10 through a seawater-fresh water heat exchanger to cool the engine; the seawater pipe 10 is configured to have an insulation layer made of polyurethane (PU) foam material, the insulation layer thickness δ is 30mm, and the insulation layer material thermal conductivity λ is 0.025W / (m·K). Other design parameters are preset according to the extremely low temperature environment conditions and the anti-icing / de-icing requirements of the pipeline, such as the ambient temperature T in the cabin. e The target temperature of electric heating is 253.15K. p is 273.15K, and the heat exchange coefficient α between the seawater pipe 10 and the non-forced convection air in the cabin is 11.65W / (m2·K). The first required power is calculated as follows:

[0116]

[0117] Taking into account that the speed of ships during navigation in polar waters is usually low, the output power of the diesel engine is small, the heat generation is small, and the cooling demand and the heat exchange demand of the heat exchanger are reduced. Therefore, the liquid seawater medium in the seawater pipe 10 is preset to flow at a lower speed, which meets the heat exchange demand while helping to reduce the energy consumption of pumping seawater; on the other hand, due to the low heat generation of the engine, the return water pipe of the seawater absorbs little heat, and then the heating effect of the return water pipe on the seawater inlet (and ice storage bin, etc.) of the ship is attenuated, resulting in an increase in the ice crystal content inside the seawater pipe 10; taking into account the above influencing factors and design conditions, goals, etc., the seawater medium flow rate v in the seawater pipe 10 is preset to be 0.5m / s, the preset ice crystal integral fraction change, that is, the ice crystal integral fraction IPF value is 20%, and the ice crystal density ρ i is 917kg / m3, and the specific heat capacity of ice crystals C p is 2090 J / (kg·K), and the ice crystal reference temperature T f is 271.51K; the second required power is calculated as follows:

[0118]

[0119] According to the safety design requirements, the safety margin factor j is preset to 15%. According to the nominal maximum heating power of the electric heating cable product, the maximum heating power P0 of each electric heating cable within 20 unit length is preset to 60W / m. The number of electric heating cables N is calculated to meet the following requirements:

[0120] N≥(1+0.15)×(10.28+399.90)÷60=7.86

[0121] The number N of electric heating cables is 8, the preset electric heating cable density parameter k is 1.2, and the reference angle θ0 of the electric heating cable position is calculated as follows:

[0122]

[0123] The angular coordinate λ of each of the electric heating cables 20 is calculated in sequence:

[0124] θ={0, 0.5852, 1.2875, 2.1303, π, 4.1529, 4.9956, 5.6979}

[0125] Accordingly, a plurality of electric heating cables 20 are arranged circumferentially on the seawater pipeline 10 , such that the number of the electric heating cables 20 in the first area 11 is greater than the number of the electric heating cables 20 in the second area 12 .

[0126] like Figure 8As shown, the control method of the seawater pipeline electric heating system 1 is configured as follows: based on safety design requirements, the temperature threshold of the seawater inlet end of the seawater pipeline 10 is preset to 275.15K, the ice crystal volume fraction threshold of the seawater outlet end is preset to 2%, and the system control cycle period is 10s; in each control cycle, the following steps are performed:

[0127] S1001. Measure and determine the seawater temperature T at the seawater inlet;

[0128] If T≥275.15K, skip steps S1002, S1003, and S1004 until entering the next control cycle after 10 seconds;

[0129] If T<275.15K, execute step S1002;

[0130] S1002. Measure and determine the ice crystal integral fraction IPF at the seawater outlet;

[0131] If IPF is ≥ 2%, each of the electric heating cables 20 outputs the maximum heating power, i.e. 60 W / m;

[0132] If IPF<2%, the PID controller processes the output power of each of the electric heating cables 20 based on the difference between the measured ice crystal integral fraction IPF and the target ice crystal integral fraction threshold, with the limit not exceeding 60W / m; wherein the output power of the nth electric heating cable 20 is recorded as kn, so that the sum of the output powers of the electric heating cables 20 in the first area 11 and the second area 12 are equal, that is, k1+k2+k3+k7+k8=k4+k5+k6.

[0133] S1003. The output power control signal is distributed to each of the electric heating cables 20 for heating;

[0134] S1004. Determine whether a stop signal is received;

[0135] If yes, the electric heating cable 20 stops heating;

[0136] If not, heat it for 10 seconds and then enter the next control cycle.

[0137] In summary, the seawater pipeline electric heating system and control method thereof, seawater pipeline anti-icing and de-icing method, etc. described in the above embodiments have beneficial effects including but not limited to at least one of the following:

[0138] Arranging electric heating tapes in seawater pipelines can achieve thermal insulation and anti-freezing of the pipelines, thereby avoiding ice blockage problems in the pipelines and improving the reliability and safety of the seawater pipeline system and ship operation; according to the flow state of the seawater-ice crystal two-phase flow, ice crystal particles and the like are more distributed in the upper area in the seawater medium, so the electric heating tapes are arranged in different areas, so that the electric heating tapes can output greater heating power in the first area of the seawater pipeline than in the second area, which can avoid excessive heating of the liquid seawater medium and enable heat to be efficiently transferred to ice crystal particles and the like, which is beneficial to improving the heating efficiency of the system and reducing energy consumption; the overall structure is streamlined and occupies less space, which is conducive to realizing compact spatial layout of the pipeline.

[0139] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed using a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0140] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read and write information from / to the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and storage medium may reside in a user terminal as discrete components.

[0141] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Computer-readable media include both computer storage media and communication media, including any media that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0142] Although the present application discloses the preferred embodiments as described above, they are not intended to limit the present application. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application shall fall within the scope of protection defined by the claims of the present application.

Claims

1. A seawater pipeline electric heating system, characterized in that: Comprising: Seawater pipeline; A plurality of electric tracing tapes, circumferentially distributed on the pipeline cross-section of the seawater pipeline; wherein, The seawater pipeline is configured to be connected at both ends by a first region and a second region to form a complete pipeline cross-section, and the hollow part of the pipeline cross-section forms a fluid channel; the first region and the second region are divided by the middle horizontal plane of the fluid channel, and the first region is located above the second region; and the sum of the maximum heating powers of the electric tracing tapes located in the first region is greater than the sum of the maximum heating powers of the electric tracing tapes located in the second region.

2. The seawater pipeline electric heating system according to claim 1, characterized in that: The sum of the maximum heating powers of all the electric tracing tapes is greater than or equal to the total required power; the total required power includes a first required power and a second required power; the first required power is equal to the heat dissipation loss of the seawater pipeline; the second required power is determined according to the heating requirement for melting at least part of the ice crystals.

3. The seawater pipeline electric heating system according to claim 2, characterized in that: The total required power satisfies the relation: P min =Q1+Q2 Where, P min represents the total required power; Q1 represents the first required power; Q2 represents the second required power; the second required power satisfies the relationship: Where d is the diameter of the seawater pipe; v is the velocity of the seawater medium; ρ i represents ice crystal density; IPF represents ice crystal volume fraction; C p represents the specific heat capacity of ice crystals; T p Indicates the target temperature of electric heating; T f Indicates the ice crystal reference temperature; l indicates the heating length of the electric heating tape.

4. The seawater pipeline electric heating system according to claim 2, characterized in that: The number of the electric tracing tapes satisfies the relation: N≥(1+j)·P min / P0 In the formula, N represents the number of electric tracing tapes; j represents the safety margin factor; P min represents the total required power; P0 represents the maximum heating power of a single electric heating tape.

5. The seawater pipeline electric heating system according to claim 4, characterized in that: Taking the center of the pipeline cross-section as the pole and the axis along the vertical upward direction as the polar axis to establish a polar coordinate system; in the polar coordinate system, the angular coordinate of the electric tracing tape is represented as θ, with the unit of rad, and the angular coordinate of the nth electric tracing tape is denoted as θ(n), n = 1,..., N, and satisfies the relation: Wherein, In the formula, θ0 represents the reference angular position of the electric tracing tape; k represents the electric tracing tape density parameter, with a value greater than 1; N represents the number of electric tracing tapes, with a value of an even number greater than or equal to 2.

6. The seawater pipeline electric heating system according to claim 1, characterized in that: The seawater pipeline electric tracing heating system further includes: a temperature measurement unit for obtaining the temperature value of the seawater in the seawater pipeline and outputting it to the power control unit; an ice crystal volume fraction measurement unit for obtaining the IPF value of the seawater in the seawater pipeline and outputting it to the power control unit; a power control unit for controlling the heating power output by each electric tracing tape according to the information obtained from the temperature measurement unit and the ice crystal volume fraction measurement unit.

7. A control method for a marine seawater pipeline electric heating system, characterized in that: The seawater pipeline electric tracing heating system is the seawater pipeline electric tracing heating system according to any one of claims 1 to 6; the control method includes: controlling the heating power output by each electric tracing tape according to the temperature value and IPF value of the seawater in the seawater pipeline.

8. The control method according to claim 7, characterized in that: The seawater pipeline has a first end and a second end, and seawater flows from the first end to the second end, and the electric tracing tapes are arranged between the first end and the second end; The seawater pipeline electric tracing heating system has a first mode and a second mode; In the first mode, each electric tracing tape outputs the maximum heating power; In the second mode, the heating power output by each electric tracing tape is determined according to the IPF value in the seawater pipeline; the control method includes repeatedly performing the following steps: S101. Judge whether the temperature value T at the first end reaches a preset temperature threshold Ts; If T≥Ts, skip step S102; if T<Ts, execute step S102; S102. Determine whether the IPF value of the second end reaches the preset ice crystal volume fraction threshold IPFs; if IPF ≥ IPFs, run the first mode; if IPF < IPFs, run the second mode.

9. A method for anti-icing and de-icing seawater pipelines for ships, characterized in that: Comprising: Circumferentially arranging a plurality of electric tracing tapes on the pipe cross-section of the seawater pipe; The electric tracing tape outputs heat to melt the ice crystals in the seawater pipe; wherein, The seawater pipe is configured such that the first region and the second region are connected at both ends to form the complete pipe cross-section, and the hollow part of the pipe cross-section forms a fluid channel; the first region and the second region are divided by the middle horizontal plane of the fluid channel, and the first region is located above the second region; and the sum of the maximum heating powers of the electric tracing tapes located in the first region is greater than the sum of the maximum heating powers of the electric tracing tapes located in the second region.

10. The anti-icing and de-icing method according to claim 9, characterized in that: Further comprising: Obtaining the total required power of the electric tracing heating system for the seawater pipe; Obtaining the number of electric tracing tapes according to the total required power; Obtaining the distribution position of each electric tracing tape according to the number of electric tracing tapes, such that the number of electric tracing tapes in the first region is greater than the number of electric tracing tapes in the second region.

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