Thermal insulation structure of tail end of ship fire-fighting pipeline and thermal insulation performance calculation method

Abstract

According to the thermal insulation structure at the tail end of the ship fire-fighting pipeline and the thermal insulation performance calculation method, the thermal insulation layer extends upwards along the tail end section of the fire-fighting pipeline, and the thermal insulation layer is longer than the tail end section, so that thermal insulation protection is formed for a water outlet of the fire-fighting pipeline, and too fast heat loss is avoided; and therefore, a better heat preservation effect is achieved on the fire-fighting medium. Meanwhile, a calculation model of the heat preservation performance is provided for the heat preservation structure, the calculation model fully considers the heat lost when a fire fighting medium passes through an air cavity channel, namely the heat preservation layer, and the heat transmitted to the tail end by other sections in the fire fighting pipeline, and the heat preservation performance of the wrapped heat preservation layer can be judged through formula calculation. Compared with other technologies, the pipeline tail end heat preservation mode provided by the invention is simple and easy to implement, the calculation mode of the heat preservation performance is simple, the calculation efficiency is high, the reliability and safety of a fire fighting system are ensured, and a scientific basis is provided for heat preservation design and construction of ship fire fighting pipelines.

Description

Technical Field

[0001] The present invention relates to the technical field of ship anti-freeze fire protection, and particularly to a heat preservation structure at the end of a ship fire-fighting pipeline and a calculation method for heat preservation performance. Background Art

[0002] During the navigation of a ship, the normal operation of the fire protection system is crucial. In case of a fire, the fire protection system can quickly deliver the fire protection medium to the fire site, effectively protecting the lives of passengers and the property safety of shipowners and cargo owners. In order to ensure the normal operation of the fire-fighting pipeline in a cold environment, a heat preservation layer is usually used to wrap the pipeline to avoid the occurrence of pipeline blockage caused by the freezing of the fire protection medium in the pipeline. The end of the fire-fighting pipeline, as the water outlet of the fire protection water, will be directly exposed to the cold air. When there is fire protection water remaining inside the pipeline, it is easy to cause the freezing of the fire protection water. Therefore, a reasonable layout of the heat preservation layer at the end of the fire-fighting pipeline is of great significance for ensuring ship fire safety. Currently, there is no method for the layout of the heat preservation layer at the end of the ship fire-fighting pipeline and the calculation of heat preservation performance. Therefore, a simple and easy-to-implement heat preservation layer layout and heat preservation performance calculation method with good heat preservation effect is needed. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for arranging the heat preservation layer at the end of a ship fire-fighting pipeline and calculating the heat preservation performance, so as to solve the problems in the prior art that the heat preservation effect at the end of the ship fire-fighting pipeline is poor, affecting the normal operation of the fire protection system and the fire extinguishing efficiency.

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a heat preservation structure at the end of a ship fire-fighting pipeline, and the heat preservation structure includes:

[0005] A fire-fighting pipeline, the fire-fighting pipeline includes a vertical end section, the upper end surface of the end section is a water outlet, and the fire-fighting pipeline is filled with a fire protection medium;

[0006] A heat preservation layer, the heat preservation layer is cylindrical, the heat preservation layer is wrapped around the outer side wall of the end section and extends upward, and the part of the heat preservation layer protruding upward from the upper end surface of the end section encloses an air cavity.

[0007] Optionally, the fire protection medium is seawater.

[0008] Optionally, the thickness of the heat preservation layer is 50 mm, the diameter of the fire-fighting pipeline is 60 mm, the length of the end section is 10 cm, and the length of the air cavity is 10 cm.

[0009] The present invention also provides a calculation method for the heat preservation performance of the heat preservation structure, including the following steps:

[0010] S1: Select the end of the fire pipeline as the research object. Determine the physical information of the end of the fire pipeline according to the specific environmental conditions and heat preservation requirements, including the inner diameter R of the fire pipeline, the thickness H of the thermal insulation layer, and the thermal conductivity K2 of the thermal insulation layer.

[0011] S2: Determine the length L of the air cavity surrounded by the thermal insulation layer.

[0012] S3: Construct a heat transfer model for the end of the fire pipeline.

[0013] S4: Calculate the heat preservation performance of the fire medium under the heat preservation layer layout method.

[0014] Optionally, when constructing the heat transfer model, set the physical conditions based on the actual operating environment, including:

[0015] Set the water temperature of the fire medium in the end section to be consistent during the calculation process.

[0016] Set the heat exchange between the air cavity and the thermal insulation layer to be negligible.

[0017] Set the heat loss of the fire pipeline wall to be ignored.

[0018] Set the thermal conductivity of the air in the air cavity to be a constant.

[0019] Set the temperature of the upper end face of the air cavity to be consistent with the external environment temperature, and the temperature of the lower end face to be consistent with the temperature of the fire medium in the end section.

[0020] Optionally, step S4 includes:

[0021] Calculate the heat loss of the fire medium in the end section per unit time through the air cavity. The formula is:

[0022]

[0023] Calculate the heat loss of the fire medium in the end section per unit time through the thermal insulation layer. The formula is:

[0024]

[0025] During the process of the temperature of the fire medium in the end section dropping from the initial value to the freezing point temperature, the heat Q3 received by the remaining sections of the fire pipeline excluding the end section per unit time is

[0026]

[0027] Therefore, the calculation formula for the total heat loss Q of the fire medium in the end section of the fire pipeline per unit time is:

[0028] Q = Q1 + Q2 - Q3

[0029] The time T required for the fire-fighting medium in the end segment to decrease from the initial temperature to the freezing point total The calculation formula is as follows:

[0030]

[0031] Wherein, K1 is the thermal conductivity of the air duct, R is the radius of the fire-fighting pipeline, T1 is the initial temperature of the fire-fighting medium, T is the real-time temperature of the fire-fighting medium, t is the external ambient temperature, L is the length of the air duct, L * is the total length of the remaining segments, K2 is the thermal conductivity of the insulation layer, K3 is the thermal conductivity of the fire-fighting medium, l is the length of the end segment, H is the thickness of the insulation layer along the radial direction, m is the mass of the fire-fighting medium in the end segment, c p is the specific heat capacity of the fire-fighting medium, and T0 is the freezing point temperature of the fire-fighting medium;

[0032] Judge T through the above formula total Whether it meets the requirements, so as to judge the heat preservation performance of the arranged heat preservation layer.

[0033] As described above, the present invention provides a heat preservation structure and a heat preservation performance calculation method for the end of a ship fire-fighting pipeline. The heat preservation structure extends the heat preservation layer upward along the end segment of the fire-fighting pipeline. The heat preservation layer has a longer length than the end segment, so as to form a heat insulation protection for the water outlet of the fire-fighting pipeline, avoid excessive heat loss, and thus play a better heat preservation effect on the fire-fighting medium. At the same time, a calculation model for the heat preservation performance of the heat preservation structure is proposed. The calculation model fully considers the heat loss of the fire-fighting medium through the air duct, that is, the heat preservation layer, and the heat transferred from the remaining segments in the fire-fighting pipeline to the end. The heat preservation performance of the covered heat preservation layer can be determined through formula calculation. Compared with other technologies, the heat preservation method at the end of the pipeline proposed by the present invention is simple and easy to implement, the calculation method of the heat preservation performance is simple, and the calculation efficiency is high, ensuring the reliability and safety of the fire-fighting system, and providing a scientific basis for the heat preservation design and construction of ship fire-fighting pipelines. Brief Description of the Drawings

[0034] Figure 1 It is a schematic diagram of the end structure of the heat preservation layer in the embodiment of the present invention.

[0035] Figure 2 It is a flowchart of the heat preservation performance calculation method described in the embodiment of the present invention. Detailed Embodiments

[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views showing the device structure will be enlarged locally in a non-general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention here. In addition, in actual production, three-dimensional spatial dimensions including length, width, and depth should be included.

[0038] For convenience of description, spatial relationship terms such as "beneath", "below", "lower than", "under", "above", "on" etc. may be used herein to describe the relationship between one element or feature shown in the drawings and other elements or features. It will be understood that these spatial relationship terms are intended to encompass other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between... and..." means including the endpoint values.

[0039] In the context of the present application, the structure in which the first feature is "above" the second feature described may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0040] It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The type, quantity, and ratio of each component in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0041] As Figure 1 shown, the present invention provides a heat insulation structure and a heat insulation performance calculation method for the end of a ship fire pipeline. The heat insulation structure specifically includes:

[0042] A fire pipeline, the fire pipeline includes a vertical end section; the upper end surface of the end section is a water outlet, and the fire pipeline is filled with a fire medium;

[0043] A heat insulation layer, the heat insulation layer is cylindrical, the heat insulation layer covers the outer side wall of the end section and extends upward, and the part of the heat insulation layer protruding upward from the upper end surface of the end section encloses an air channel.

[0044] The thermal insulation structure extends the thermal insulation layer upward along the fire pipeline, that is, it has a longer length compared to the end section, so as to form thermal insulation protection for the water outlet of the fire pipeline and avoid excessive heat loss.

[0045] Based on the above thermal insulation structure, the present invention also provides a corresponding thermal insulation performance calculation method, as Figure 2 shown, including the following steps:

[0046] S1: Select the end of the fire pipeline as the research object, and determine the physical information of the end of the fire pipeline according to the specific environmental conditions and thermal insulation requirements, including the inner diameter R of the fire pipeline, the thickness H of the thermal insulation layer, and the thermal conductivity K2 of the thermal insulation layer;

[0047] S2: Determine the length L of the air cavity surrounded by the thermal insulation layer, that is, the length of the thermal insulation layer extending from the end of the fire pipeline;

[0048] S3: Construct a heat transfer model for the end of the fire pipeline;

[0049] S4: Calculate the thermal insulation performance of the fire medium under the thermal insulation layer layout method.

[0050] Optionally, when constructing the heat transfer model, set the physical conditions based on the actual operating environment, including:

[0051] Set the water temperature of the fire medium in the end section to be consistent during the calculation process; since the length of the end section is very short, the fluctuation of the water temperature at the end of the pipeline caused by heat loss or flow can be ignored.

[0052] Set the heat exchange between the air cavity and the thermal insulation layer to be negligible; since the air cavity exchanges heat with the outside mainly through the cavity rather than the side wall, the heat exchange between the air cavity and the thermal insulation layer can be ignored.

[0053] Set the heat loss of the fire pipeline wall to be ignored; since the material of the fire pipeline is metal, the thermal conductivity of the metal pipe wall is high and the thermal resistance is much smaller than that of the thermal insulation layer, so it can be considered that the pipe wall does not dissipate heat during heat conduction.

[0054] Set the thermal conductivity of the air in the air cavity to be a constant; since the temperature change in the air cavity is small, it can be considered that the air thermal conductivity does not change with temperature.

[0055] Set the temperature of the upper end face of the air cavity to be the same as the outside environmental temperature, and the temperature of the lower end face to be the same as the temperature of the fire medium; that is, set the temperature of the upper end face of the air cavity = environmental temperature, and the temperature of the lower end face = the temperature of the fire medium in the end section.

[0056] The physical meaning of the above relevant settings is: regarding the air cavity as a linear heat transfer medium, which conforms to the steady-state heat conduction model.

[0057] Optionally, in step S4, it specifically includes:

[0058] Calculate the heat loss of the fire-fighting medium in the end segment per unit time through the air channel. The formula is:

[0059]

[0060] Calculate the heat loss of the fire-fighting medium in the end segment per unit time through the heat-insulating layer. The formula is:

[0061]

[0062] In addition, considering that the fire-fighting medium in the end segment will exchange heat with the fire-fighting medium in the remaining segments of the fire-fighting pipeline connected below except for the end segment. Assume that when the temperature of the fire-fighting medium in the end segment reaches the freezing point, the temperature at the initial end of the fire-fighting pipeline far from the end segment is still the initial temperature. At this time, due to the solidification of the medium, no heat exchange occurs between the end segment and the remaining segments. Therefore, the heat Q3 received from the remaining segments per unit time during the process of the temperature of the fire-fighting medium in the end segment dropping from the initial value to the freezing point can be calculated as

[0063]

[0064] In the above expressions, Q1, Q2, and Q3 all adopt the calculation method of temperature difference compromise. Since the real-time temperature T of the fire-fighting medium changes in real time, in the heat conduction process, the greater the temperature difference, the faster the heat transfer, and the smaller the temperature difference, the slower the heat transfer. Therefore, here the temperature difference between the real-time temperature T of the end segment and the temperature at the other end during the heat transfer process is simplified to 1 / 2 of the maximum temperature difference between the end segment and the other end during the heat transfer process and remains constant. At the same time, the thermal conductivity coefficient also remains unchanged for easy calculation. In the above expressions, T - t is simplified to (T1 - t) / 2, and T1 - T is simplified to (T1 - T0) / 2.

[0065] Therefore, the calculation formula for the total heat loss Q of the fire-fighting medium in the end segment of the fire-fighting pipeline per unit time is:

[0066] Q = Q1 + Q2 - Q3

[0067] After derivation, the time T total required for the fire-fighting medium in the end segment to drop from the initial temperature to the freezing point is calculated as:

[0068]

[0069] where K1 is the thermal conductivity coefficient of the air channel, R is the radius of the fire-fighting pipeline, T1 is the initial temperature of the fire-fighting medium, T is the real-time temperature of the fire-fighting medium, t is the external ambient temperature, L is the length of the air channel, L* is the total length of the remaining segments, K2 is the thermal conductivity of the thermal insulation layer, K3 is the thermal conductivity of the fire protection medium, l is the length of the end segment, H is the radial thickness of the thermal insulation layer, m is the mass of the fire protection medium in the end segment, c p is the specific heat capacity of the fire protection medium, and T0 is the freezing point temperature of the fire protection medium.

[0070] Furthermore, determine the time T required for the calculated initial temperature of the fire protection medium to drop to the freezing point total Whether it meets the requirements can be used to judge the thermal insulation performance of the arranged thermal insulation layer.

[0071] Example 1

[0072] S1: Select the end of the fire protection pipeline of a certain ship type as the research object, cut it into a suitable shape according to the pipeline size so that it can fit tightly on the surface of the pipeline end. The technical condition for judging the thermal insulation performance is that the medium at the pipeline end does not reach the freezing point temperature within 12 hours. The relevant physical parameters are: the thermal conductivity K2 of the thermal insulation material is 0.03 W / (m·k), the external environmental temperature t is -10°C, and the thermal conductivity K1 of the air is 0.025 W / (m·k); the fire protection medium is seawater, the initial temperature T1 is 5°C, the freezing point temperature T0 is -1°C, and the specific heat capacity c p is 3890 J / (kg·°C), the thickness H of the thermal insulation layer is 50 mm, the diameter of the fire protection pipeline is 60 mm, the length of the thermal insulation layer in the fire protection medium area, that is, the length l of the end segment, is 10 cm, and the total length of the fire protection pipeline in the remaining area, that is, the length L of the remaining segments * is 60 cm;

[0073] S2: Determine the length of the thermal insulation layer extended from the end of the fire protection pipeline, that is, the length L of the air cavity is 10 cm;

[0074] S3: Construct a heat transfer model for the end of the fire protection pipeline;

[0075] S4: Calculate the time for the seawater in the pipeline to drop from 5°C to -1°C through the heat transfer model at the end of the fire protection pipeline: T total ≈ 23 hours, meeting the requirements of thermal insulation performance.

[0076] In summary, the present invention provides a heat preservation structure at the end of a ship's fire fighting pipeline and a calculation method for heat preservation performance. The heat preservation structure extends the heat preservation layer upward along the end section of the fire fighting pipeline. The heat preservation layer has a longer length compared to the end section, thereby forming heat insulation protection for the water outlet of the fire fighting pipeline, avoiding excessive heat loss, and further achieving a better heat preservation effect on the fire fighting medium. At the same time, a calculation model for heat preservation performance is proposed for the heat preservation structure. The calculation model fully considers the heat lost by the fire fighting medium through the air cavity, that is, the heat preservation layer, and the heat transferred from the other sections in the fire fighting pipeline to the end. The heat preservation performance of the covered heat preservation layer can be determined through formula calculation. Compared with other technologies, the heat preservation method at the end of the pipeline proposed by the present invention is simple and easy to implement, the calculation method of heat preservation performance is simple and the calculation efficiency is high, ensuring the reliability and safety of the fire fighting system, and providing a scientific basis for the heat preservation design and construction of ship fire fighting pipelines.

[0077] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. An insulation structure at the end of a ship's fire-fighting pipeline, characterized in that, The thermal insulation structure includes: A fire-fighting pipeline, the fire-fighting pipeline includes a vertical end section, the upper end surface of the end section is a water outlet, and the fire-fighting pipeline is filled with a fire-fighting medium; A thermal insulation layer, the thermal insulation layer is cylindrical, the thermal insulation layer covers the outer side wall of the end section and extends upward, and the part of the thermal insulation layer protruding upward from the upper end surface of the end section encloses an air cavity.

2. The heat insulation structure at the end of the ship's fire-fighting pipeline according to claim 1, characterized in that: The fire-fighting medium is seawater.

3. The heat insulation structure at the end of the ship's fire-fighting pipeline according to claim 1, characterized in that: The thickness of the thermal insulation layer is 50 mm, the diameter of the fire-fighting pipeline is 60 mm, the end section is 10 cm, and the length of the air cavity is 10 cm.

4. A method for calculating the heat insulation performance of the heat insulation structure according to any one of claims 1-3, characterized in that, It includes the following steps: S1: Select the end of the fire-fighting pipeline as the research object, and determine the physical information of the end of the fire-fighting pipeline according to the specific environmental conditions and thermal insulation requirements, including the inner diameter R of the fire-fighting pipe, the thickness H of the thermal insulation layer, and the thermal conductivity K2 of the thermal insulation layer; S2: Determine the length L of the air cavity enclosed by the thermal insulation layer; S3: Construct a heat transfer model of the end of the fire-fighting pipeline; S4: Calculate the thermal insulation performance of the fire-fighting medium under the thermal insulation layer layout method.

5. The heat preservation performance calculation method according to claim 4, characterized in that: When constructing the heat transfer model, set physical conditions based on the actual operation environment, including: Set the water temperature of the fire-fighting medium in the end section to be consistent during the calculation process; Set the heat exchange between the air cavity and the thermal insulation layer to be negligible; Set the heat loss of the fire-fighting pipeline wall to be ignored; Set the thermal conductivity of the air in the air cavity to be a constant; Set the temperature of the upper end surface of the air cavity to be consistent with the external environment temperature, and the temperature of the lower end surface to be consistent with the temperature of the fire-fighting medium in the end section.

6. The heat preservation performance calculation method according to claim 4, characterized in that: Step S4 includes: Calculate the heat loss of the fire-fighting medium in the end section per unit time through the air cavity, and the formula is: Calculate the heat loss of the fire-fighting medium in the end section per unit time through the thermal insulation layer, and the formula is: The heat Q3 received by the remaining sections of the fire-fighting pipeline excluding the end section per unit time when the temperature of the fire-fighting medium in the end section drops from the initial value to the freezing point temperature is Therefore, the calculation formula for the total heat loss Q of the fire-fighting medium in the end section of the fire-fighting pipeline per unit time is: Q = Q1 + Q2 - Q3 The time T required for the fire-fighting medium in the end segment to be reduced from the initial temperature to the freezing point total The calculation formula is as follows: Among them, K1 is the thermal conductivity of the air channel, R is the radius of the fire pipeline, T1 is the initial temperature of the fire-fighting medium, T is the real-time temperature of the fire-fighting medium, t is the external ambient temperature, L is the length of the air channel, L * is the total length of the remaining segments, K2 is the thermal conductivity of the insulation layer, K3 is the thermal conductivity of the fire-fighting medium, l is the length of the end segment, H is the thickness of the insulation layer along the radial direction, m p is the mass of the fire-fighting medium in the end segment, c is the specific heat capacity of the fire-fighting medium, and T0 is the freezing point temperature of the fire-fighting medium; Judge T according to the above formula total to determine whether the requirements are met, so as to judge the heat preservation performance of the arranged heat preservation layer.

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