Composite pipeline thermal insulation layer and performance testing method thereof

Abstract

The invention belongs to the technical field of pipeline thermal insulation layers, and discloses a composite pipeline thermal insulation layer and a performance testing method thereof.The composite pipeline thermal insulation layer comprises a first thermal insulation layer and a second thermal insulation layer which are equal in thickness, the inner diameter of the first thermal insulation layer is equal to the outer diameter of a pipeline, and the inner diameter of the second thermal insulation layer is equal to the outer diameter of the first thermal insulation layer; the first thermal insulation layer is made of aerogel or foam glass, and the second thermal insulation layer is made of aerogel or foam glass; the test method comprises the following steps: S1, acquiring parameters; s2, establishing a mathematical model; s3, calculating temperature, displacement and radial stress; and S4, based on the parameters obtained in the step S3, analyzing the thermal insulation performance of the pipeline thermal insulation layer. The pipeline heat preservation layer is good in heat preservation effect, and heat dissipation loss of media in the pipeline is reduced; and a performance analysis test method is established, the influence rule of the interface thermal resistance and different thermal insulation layer materials on the thermal response is analyzed, and a theoretical basis is provided for optimizing the thermal insulation layer and the performance of the composite pipeline.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline thermal insulation layers, and in particular to a composite pipeline thermal insulation layer and a performance testing method thereof. Background Art

[0002] The pipeline insulation layer, also known as the thermal pipeline insulation layer, is the main body of the insulation structure. Its main purpose is to reduce the heat loss of the medium to meet the pressure and temperature required for production. At the same time, by maintaining the temperature of the pipeline, it prevents the liquid in the pipeline from freezing or condensation on the outer surface, ensuring the normal operation and safety of the pipeline system.

[0003] The purpose of adding an insulation layer to the outside of the pipeline is to save energy, ensure the stable temperature transmission of the medium inside the pipeline, and prevent the external environment from affecting the temperature of the pipeline. If the insulation layer is not added, the temperature inside the pipeline is easy to lose, and for high-temperature media, it will cause energy waste and increase the cost of use, and it is also easy to cause condensation and corrosion of the pipeline. After adding the insulation layer, energy consumption can be reduced, waste can be reduced, the temperature of the medium inside the pipeline can be ensured to be stably transmitted, and the service life of the pipeline can be increased.

[0004] Therefore, an insulation layer with good thermal insulation effect is essential for pipeline transportation media. Summary of the invention

[0005] The present invention aims to provide a composite pipe insulation layer and a performance testing method thereof. The composite pipe insulation layer is different from the existing insulation layer. It is composed of aerogel and foam glass, has good insulation effect, and reduces the heat dissipation loss of the medium inside the pipe. A performance testing method is established to analyze the influence of interface thermal resistance and different insulation layer materials on thermal response, so as to provide a theoretical basis for optimizing the composite pipe insulation layer and performance.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A composite pipe insulation layer and a performance testing method thereof, comprising a first insulation layer and a second insulation layer of equal thickness, wherein the inner diameter of the first insulation layer is equal to the outer diameter of the pipe, and the inner diameter of the second insulation layer is equal to the outer diameter of the first insulation layer; the first insulation layer is aerogel or foam glass, and the second insulation layer is aerogel or foam glass.

[0008] Furthermore, the first thermal insulation layer and the second thermal insulation layer are both aerogel or foam glass.

[0009] Furthermore, the first thermal insulation layer is aerogel, and the second thermal insulation layer is foam glass.

[0010] Furthermore, the first thermal insulation layer is foam glass, and the second thermal insulation layer is aerogel.

[0011] The above-mentioned method for testing the performance of a composite pipe insulation layer comprises the following steps:

[0012] S1. Apply uniform thermal shock to the inner wall of the first thermal insulation layer, and obtain reference temperature, inner diameter and outer diameter of the first thermal insulation layer, outer diameter of the second thermal insulation layer, thickness of the first thermal insulation layer and the second thermal insulation layer, and interface thermal resistance;

[0013] S2, establishing a displacement control model and a temperature control model;

[0014] S3. Combining the initial conditions, boundary conditions and interface conditions, the displacement control model and temperature control model of step S2 are solved by using Laplace transform and its inverse transform to obtain the temperature, displacement and radial stress of the pipeline insulation layer and the surrounding soil;

[0015] S4. Analyze the thermal insulation performance of the pipeline insulation layer based on the temperature, displacement and radial stress of the pipeline insulation layer and the surrounding soil obtained in S3.

[0016] Furthermore, in S2, the displacement control model and the temperature control model are respectively:

[0017]

[0018]

[0019] Among them, λ i and μ i is the Lamé constant, is the volume strain, u r is the radial displacement, θ=T-T0 is the temperature, T and T0 are the absolute temperature and the reference temperature outside the pipe respectively, β i =(3λ i +2μ i )α ti , where α ti is the coefficient of thermal expansion, is the Laplace differential operator, ρ i is the density, κ i is the thermal conductivity coefficient, t is the time, c is the specific heat capacity, r is an arbitrary radius, ri=r1, r2, r3 represent the inner diameter of the first thermal insulation layer, the outer diameter of the first thermal insulation layer, and the outer diameter of the second thermal insulation layer respectively.

[0020] The beneficial effects of the technical solution are:

[0021] 1. The present invention is composed of two layers of materials (aerogel and / or foam glass). Foam glass is a porous material made of glass as raw material, which is melted at high temperature, added with a foaming agent, and then processed by a special processing technology. The foam glass is characterized by a uniform and continuous fine pore structure, good thermal insulation, heat insulation, sound absorption and fire resistance, as well as high strength and durability. Aerogel is a three-dimensional continuous porous material composed of nanopores and nanoskeletons. Its unique structure makes it have many incomparable properties of conventional materials, the most notable of which is its extremely low thermal conductivity. The first insulation layer is in direct contact with the second insulation layer, and the second insulation layer is in contact with the soil. The interface thermal resistance between the first insulation layer and the second insulation layer and the interface thermal resistance between the second insulation layer can reduce heat loss, thereby increasing the insulation effect of the insulation layer and reducing the heat dissipation loss of the medium inside the pipeline.

[0022] 2. The present invention establishes a performance testing method. By testing the performance of the pipeline insulation layer and analyzing the influence of the interface thermal resistance and different insulation layer materials on the thermal response, it can be understood whether the pipeline insulation layer meets the design requirements and whether there are any hidden dangers in the insulation performance, thereby providing a theoretical basis for optimizing the composite pipeline insulation layer and performance and improving the energy utilization efficiency of the pipeline system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a composite pipeline insulation layer of the present invention;

[0024] Figure 2 This is a curve diagram showing the effect of the interfacial thermal resistance on the temperature of the composite pipe insulation layer in Example 1 of the present invention;

[0025] Figure 3 This is a curve diagram showing the effect of the interfacial thermal resistance on the displacement of the composite pipe insulation layer in Example 1 of the present invention;

[0026] Figure 4 This is a curve diagram showing the influence of the interfacial thermal resistance on the radial stress of the composite pipe insulation layer in Example 1 of the present invention;

[0027] Figure 5 This is a curve diagram showing the effect of the interfacial thermal resistance on the temperature of the composite pipe insulation layer in Example 2 of the present invention;

[0028] Figure 6 This is a curve diagram showing the effect of the interfacial thermal resistance on the displacement of the composite pipe insulation layer in Example 2 of the present invention;

[0029] Figure 7 This is a curve diagram showing the influence of the interfacial thermal resistance on the radial stress of the composite pipe insulation layer in Example 2 of the present invention;

[0030] Figure 8This is a curve diagram showing the effect of the interfacial thermal resistance on the temperature of the composite pipe insulation layer in Example 3 of the present invention;

[0031] Fig. 9 This is a curve diagram showing the effect of the interfacial thermal resistance on the displacement of the composite pipe insulation layer in Example 3 of the present invention;

[0032] Fig.10 This is a curve diagram showing the influence of the interfacial thermal resistance on the radial stress of the composite pipe insulation layer in Example 3 of the present invention;

[0033] Fig.11 This is a graph showing the effect of the composite pipe insulation layer made of different materials on the temperature in Example 4 of the present invention;

[0034] Fig.12 This is a graph showing the influence of composite pipe insulation layers made of different materials on displacement in Example 4 of the present invention;

[0035] Fig.13 This is a curve diagram showing the influence of composite pipe insulation layers made of different materials on radial stress in Example 4 of the present invention;

[0036] The names of the corresponding marks in the accompanying drawings are:

[0037] The first thermal insulation layer 1, the second thermal insulation layer 2, and the surrounding soil 3. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0039] Example 1

[0040] like Figure 1 As shown, a composite pipe insulation layer comprises a first insulation layer 1 and a second insulation layer 2 of equal thickness, the inner diameter of the first insulation layer 1 is equal to the outer diameter of the pipe, and the inner diameter of the second insulation layer 2 is equal to the outer diameter of the first insulation layer 1; the first insulation layer 1 and the second insulation layer 2 are both aerogel or foam glass;

[0041] The above-mentioned performance testing method of a composite pipe insulation layer comprises the following steps:

[0042] S1, apply uniform thermal shock to the inner wall of the first insulation layer 1, and refer to the temperature T0, the inner diameter and outer diameter of the first insulation layer 1, the outer diameter of the second insulation layer 2, are r1, r2, r3 respectively, the thickness of the first insulation layer 1 and the second insulation layer 2, are h1 = r2-r1, h2 = r3-r2 respectively, the interface thermal resistance between the first insulation layer 1 and the second insulation layer 2, and the interface thermal resistance between the second insulation layer 2 and the surrounding soil 3, are R θ1 ,R θ2 ;

[0043] Among them, the dimensionless thickness of the first insulation layer 1 and the second insulation layer 2 is h=0.5, the dimensionless radius of the pipeline (the dimensionless inner diameter of the first insulation layer 1) is r1=1, the dimensionless outer diameter of the first insulation layer 1 (the inner diameter of the second insulation layer 2) is r2=1.5, the dimensionless outer diameter of the second insulation layer 2 is r3=2, the time t=1; the uniform thermal shock is T(t);

[0044] The parameters of surrounding soil 3 are:

[0045] λ3=7.76×10 7 Pa, μ3=3.86×10 6 Pa, ρ3=1800kgm 3 , k3=3.8W(m·k),

[0046] α t3 =1.78×10 -5 ℃, T0=293K, C E3 =2000m 2 ·s -2 ℃ -1 .

[0047] The first insulation layer 1 and the second insulation layer 2 are made of the same material, and their parameters are:

[0048] λ1=λ2=9.2λ3, μ1=μ2=9μ3, ρ1=ρ2=1.3ρ3, k1=k2=1.5k3,

[0049] α t1 =α t2 =0.8α t3 , T0=293K, C E1 =C E2 =1.3C E3 .

[0050] Wherein i=1, 2, 3 represent the first insulation layer 1, the second insulation layer 2 and the surrounding soil 3 respectively.

[0051] S2, establishing a displacement control model and a temperature control model;

[0052] The expressions of displacement control model and temperature control model are:

[0053]

[0054]

[0055] Among them, λ i and μ i is the Lamé constant, is the volume strain, u ris the radial displacement, θ=T-T0 is the temperature, T and T0 are the absolute temperature and the reference temperature outside the pipe respectively, β i =(3λ i +2μ i )α ti , where α ti is the coefficient of thermal expansion, is the Laplace differential operator, ρ i is the density, κ i is the heat transfer coefficient, t is the time, c is the specific heat capacity, r is an arbitrary radius, ri=r1, r2, r3 represent the inner diameter of the first insulation layer 1, the outer diameter of the first insulation layer 1, and the outer diameter of the second insulation layer 2 respectively;

[0056] S3. Combining the initial conditions, boundary conditions and interface conditions, the displacement control model and temperature control model of step S2 are solved by using Laplace transform and its inverse transform to obtain the temperature, displacement and radial stress of the pipeline insulation layer and the surrounding soil;

[0057] The initial conditions are:

[0058]

[0059] The boundary conditions are:

[0060] σ(r1,t)=0,θ(r1,t)=θ0H(t)

[0061] u(∞,t)=θ(∞,t)=0

[0062] The interface conditions are:

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] Among them, R θ1 ,R θ2 is the interface thermal resistance between the first thermal insulation layer 1 and the second thermal insulation layer 2, and between the second thermal insulation layer 2 and the surrounding soil 3, q ​​is the heat, σ is the radial stress, r1, r2, r3 represent the inner diameter of the first thermal insulation layer 1, the outer diameter of the first thermal insulation layer 1, and the outer diameter of the second thermal insulation layer 2, respectively;

[0074] S4, analyzing the thermal insulation performance of the pipeline thermal insulation layer according to the temperature, displacement and radial stress of the pipeline thermal insulation layer and the surrounding soil obtained in S3;

[0075] Analyze and evaluate the interface thermal resistance R θ1 , R θ2 The influence on the thermal response of the structure, temperature, displacement and radial stress distribution are as follows: Figure 2-4 As shown, from Figure 2 It can be seen from the figure that when the interface thermal resistance is zero at the interface, there will be no temperature difference at that place. When there is thermal resistance, there will be a temperature difference. When there is thermal resistance on both interfaces, the effect is most significant, and the thermal insulation effect is better. The overall temperature decreases as the position increases and eventually becomes zero. Figure 3 It can be seen from the figure that when the structure is subjected to heat load, it will deform and the interface thermal resistance R θ1 The impact is more significant; Figure 4 It can be seen that the radial stress of the structure changes slightly at the beginning. The absolute value of the radial pressure increases rapidly at r = 1.5, and then decreases to zero as the position increases. The interface thermal resistance R θ1 The impact is more significant; overall, it can be seen that the interface thermal resistance R θ1 The impact is higher than the interface thermal resistance R θ2 The impact produced.

[0076] Example 2

[0077] The difference between this embodiment and embodiment 1 is:

[0078] In this embodiment, the first insulation layer 1 is aerogel, and the second insulation layer 2 is foam glass;

[0079] The first insulation layer 1 is aerogel, and the second insulation layer 2 is foam glass (i.e., the three layers of materials from inside to outside are aerogel-foam glass-soil), and their parameters are:

[0080] λ1=λ2=9.2λ3, μ1=μ2=9μ3, ρ1=200kg / m 3 ,ρ2=110kg / m 3 ,

[0081] k1=0.02W / (m·k), k2=0.04W / (m·k), α t1 =7×10 -6℃,α t2 =8.8×10 -6 ℃,

[0082] T0=293K,C E1 =C E2 =1.3C E3 .

[0083] Wherein i=1, 2, 3 represent the first insulation layer 1, the second insulation layer 2 and the surrounding soil 3 respectively.

[0084] Evaluate the interface thermal resistance R θ1 , R θ2 The influence on the thermal response of the structure, such as temperature, displacement and stress distribution Figure 5-7 As shown, from Figure 5 It can be seen from the figure that when the interface thermal resistance is zero at the interface, there will be no temperature difference at that place. When there is thermal resistance, there will be a temperature difference. When there is thermal resistance on both interfaces, the effect is most significant, and the thermal insulation effect is better. The overall temperature decreases as the position increases and eventually becomes zero. Figure 6 It can be seen from the figure that when the structure is subjected to heat load, it will deform, and when the interface thermal resistance R θ1 With R θ2 When it exists, the displacement generated at the interface will increase; Figure 7 It can be seen that the radial stress of the structure changes slightly at the beginning. The absolute value of the radial pressure increases rapidly at r = 1.5, and then decreases to zero as the position increases. The interface thermal resistance R θ2 The impact is more significant.

[0085] Example 3

[0086] The difference between this embodiment and embodiment 1 is:

[0087] In this embodiment, the first insulation layer 1 is foam glass, and the second insulation layer 2 is aerogel;

[0088] The first insulation layer 1 is foam glass, and the second insulation layer 2 is aerogel (i.e., the three layers of material from inside to outside are foam glass-aerogel-soil), and their parameters are:

[0089] λ1=λ2=9.2λ3, μ1=μ2=9μ3, ρ1=110kg / m 3 ,ρ2=200kg / m 3 ,

[0090] k1=0.04W / (m·k), k2=0.02W / (m·k), α t1 =8.8×10 -6 ℃,α t2 =7×10 -6 ℃,

[0091] T0=293K,C E1 =C E2 =1.3C E3 .

[0092] Wherein i=1, 2, 3 represent the first insulation layer 1, the second insulation layer 2 and the surrounding soil 3 respectively.

[0093] Evaluate the interface thermal resistance R θ1 , R θ2 The influence on the thermal response of the structure, such as temperature, displacement and stress distribution Figure 8-10 As shown, from Figure 8 It can be seen that when the interface thermal resistance is zero, there will be no temperature difference at the interface. When there is thermal resistance, a temperature difference will occur. The interface thermal resistance R θ1 The effect is most significant when it exists, and the heat preservation effect is better. The overall temperature decreases as the position increases and eventually becomes zero; Fig. 9 It can be seen from the figure that when the structure is subjected to heat load, it will deform and the interface thermal resistance R θ1 The effect is more obvious; Fig.10 It can be seen that the radial stress of the structure changes slightly at the beginning. The absolute value of the radial pressure increases rapidly at r = 1.5, and then decreases to zero as the position increases. The interface thermal resistance R θ1 The impact is more significant.

[0094] Example 4

[0095] Model 1, Model 2, and Model 3 respectively represent: the first insulation layer 1 and the second insulation layer 2 are the same material, the first insulation layer 1 is aerogel and the second insulation layer 2 is foam glass, the first insulation layer 1 is foam glass and the second insulation layer 2 is aerogel. The curves are plotted to analyze and evaluate the effects of different material combinations on the thermal response; the temperature, displacement, and stress distribution are shown in Figure 2. Figure 11-13 shown; from Fig.11 It can be seen that Model 1 has the best insulation effect among the three models. When comparing Model 2 and Model 3, before 1.8 on the x-axis, it is shown that Model 3 has a better insulation effect.

[0096] From the above embodiments, it can be seen that when the first insulation layer is foam glass and the second insulation layer is aerogel, the insulation effect of the pipeline is the best. When there is thermal resistance at the interface, a temperature difference will occur. As the interface thermal resistance increases, the temperature difference increases, and the interface thermal resistance R θ1 The most significant impact is on the interface temperature difference.

[0097] In summary, the present invention is composed of two layers of materials (aerogel and / or foam glass). Foam glass is a porous material made of glass as raw material, which is melted at high temperature, added with a foaming agent, and then processed by a special processing technology. The characteristics of foam glass are that it has a uniform and continuous fine pore structure, has good thermal insulation, heat insulation, sound absorption and fire resistance, and also has high strength and durability; aerogel is a three-dimensional continuous porous material composed of nanopores and nanoskeletons. Its unique structure makes it have many incomparable properties of conventional materials, the most notable of which is its extremely low thermal conductivity; and the first thermal insulation layer 1 and the second thermal insulation layer 2 are connected by a plurality of insulating layers. The first thermal insulation layer 1 is in direct contact with the second thermal insulation layer 2, and the second thermal insulation layer 2 is in direct contact with the surrounding soil 3. The interface thermal resistance between the first thermal insulation layer 1 and the second thermal insulation layer 2, and the interface thermal resistance between the second thermal insulation layer 2 and the surrounding soil 3 can reduce the heat loss, thereby increasing the thermal insulation effect of the thermal insulation layer and reducing the heat dissipation loss of the medium inside the pipeline; a performance testing method is established, and by testing the performance of the pipeline insulation layer, the influence of the interface thermal resistance and different insulation layer materials on the thermal response is analyzed, so as to understand whether the pipeline insulation layer meets the design requirements and whether there are any hidden dangers in the insulation performance, thereby providing a theoretical basis for optimizing the composite pipeline insulation layer and performance and improving the energy utilization efficiency of the pipeline system.

[0098] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the technical solution of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A composite pipe insulation layer, characterized in that: It comprises a first insulation layer and a second insulation layer of equal thickness, wherein the inner diameter of the first insulation layer is equal to the outer diameter of the pipeline, and the inner diameter of the second insulation layer is equal to the outer diameter of the first insulation layer; the first insulation layer is aerogel or foam glass, and the second insulation layer is aerogel or foam glass.

2. The composite pipe insulation layer according to claim 1, characterized in that: The first thermal insulation layer and the second thermal insulation layer are both aerogel or foam glass.

3. The composite pipe insulation layer according to claim 1, characterized in that: The first thermal insulation layer is aerogel, and the second thermal insulation layer is foam glass.

4. The composite pipe insulation layer according to claim 1, characterized in that: The first thermal insulation layer is foam glass, and the second thermal insulation layer is aerogel.

5. A performance testing method for a composite pipe insulation layer as claimed in claim 1, characterized in that: The following steps are involved: S1. Apply uniform thermal shock to the inner wall of the first thermal insulation layer, and obtain reference temperature, inner diameter and outer diameter of the first thermal insulation layer, outer diameter of the second thermal insulation layer, thickness of the first thermal insulation layer and the second thermal insulation layer, and interface thermal resistance; S2, establishing a displacement control model and a temperature control model; S3. Combining the initial conditions, boundary conditions and interface conditions, the displacement control model and temperature control model of step S2 are solved by using Laplace transform and its inverse transform to obtain the temperature, displacement and radial stress of the pipeline insulation layer and the surrounding soil; S4. Analyze the thermal insulation performance of the pipeline insulation layer based on the temperature, displacement and radial stress of the pipeline insulation layer and the surrounding soil obtained in S3.

6. A performance testing method for a composite pipe insulation layer according to claim 5, characterized in that: In S2, the displacement control model and temperature control model are: Among them, λ i and μ i is the Lamé constant, is the volume strain, u r is the radial displacement, θ=T-T0 is the temperature, T and T0 are the absolute temperature and the reference temperature outside the pipe respectively, β i =(3λ i +2μ i )α ti , where α ti is the thermal expansion coefficient, ▽ 2 is the Laplace differential operator, ρ i is the density, κ i is the thermal conductivity coefficient, t is the time, c is the specific heat capacity, r is an arbitrary radius, ri=r1, r2, r3 represent the inner diameter of the first thermal insulation layer, the outer diameter of the first thermal insulation layer, and the outer diameter of the second thermal insulation layer respectively.

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