RU105443U1 - STAND FOR HEAT-TECHNICAL TESTS OF HEAT-INSULATED PIPES - Google Patents

Abstract

 1. A stand for thermotechnical testing of thermally insulated pipes, comprising at least one thermally insulated pipe to be tested, a first heating unit, a first fan unit, an automatic control and recording unit, a first temperature measuring unit, the outputs of which are connected to the first inputs of receiving the measured temperature readings of the unit automatic control and registration, the first and second outputs of which are connected to the control inputs by turning on the first heating unit and fan unit, respectively, about characterized in that a second temperature measuring unit is introduced into it, the outputs of which are connected to the second inputs of the measured temperature readings of the automatic control and recording unit, the first and second air flow meters, the second fan unit and the heating unit, as well as a bench heat-insulated pipe placed parallel to the test heat-insulated pipe, and one pair of ends of the test and bench heat-insulated pipes are hermetically fixed by means of two technological heat-insulated couplings and is connected by the first flexible insulated pipe installed between the second air flow meter and the first fan unit and the heating unit installed in series, the output of the first flow meter is connected to the input of the testimony of the first flow meter of the automatic control and registration unit, the other pair of ends of the test and stand insulated pipes are hermetically sealed fixed by two other thermally insulated process couplings and connected by a second flexible thermally insulated pipe

Description

The utility model relates to testing techniques in the oil and gas, chemical, construction and other industries in which thermally insulated pipelines are designed, manufactured, tested and operated.

The prior art bench for simulating thermal conditions (RU 88147, U1, G01M 9/00, 10.27.2009), including a control unit and two heating systems and a fan unit electrically connected to it. The stand also includes temperature sensors, air flow velocity sensors, temperature and air flow velocity measuring units, analog-to-digital converters (ADC) units, and a computer. In this case, the stand is made in the form of a camera, the housing of which contains a heat insulating layer. The bench during testing of objects of various profiles provides the ability to set the thermal conditions to the corresponding operational loads. A well-known stand provides the opportunity for appropriate testing of objects of various profiles. However, the known solution contains a large amount of equipment necessary to ensure the operability of the stand, and is not intended for thermotechnical testing of full-scale heat-insulated pipes of oil grade.

The problem, which the present utility model is aimed at, is to create a stand for thermotechnical testing of thermally insulated pipes of oil grade, the length of which is 10-12 m or more. The weight of such a pipe can reach 500 kg or more. The heat-insulated pipe can be made in the form of an assembly of at least two or more similar pipes connected by a standard sleeve that participates together with the heat-insulated pipes in the distribution of heat fluxes in the radial direction.

The technical result of the utility model is to increase the accuracy of the test results of thermally insulated pipes of oil grade with the help of a stand designed for thermotechnical testing of thermally insulated pipes of oil grade. The technical result also consists in creating a stand that provides thermotechnical testing of heat-insulated elevator pipes not at individual points, but throughout the pipe or pipe assembly under operating conditions close to natural conditions.

The essence of the utility model is that it is a stand for thermotechnical testing of thermally insulated pipes, containing at least one tested thermally insulated pipe, a first heating unit, a first fan unit, an automatic control and registration unit, a first temperature measurement unit. The outputs of the first temperature measurement unit are connected to the first inputs of the reception of the measured temperature readings of the automatic control and registration unit. The first and second outputs of the automatic control and registration unit are connected to the control inputs by turning on the first heating unit and the first fan unit, respectively. The technical result of the proposed utility model is achieved through an additional introduction to the stand: a second temperature measurement unit, the outputs of which are connected to the second inputs of the reception of the measured temperature readings of the automatic control and registration unit; first and second air flow meters; a second fan unit and a second heating unit. In addition, a bench heat-insulated pipe placed parallel to the test heat-insulated pipe is introduced into the stand, with one pair of ends of the test and bench heat-insulated pipes sealed by two technological heat-insulated couplings and connected by a first flexible heat-insulated pipe installed between the second air flow meter and the first fan block and a heating unit, sequentially installed with the possibility of heating the circulating air flow inside and sprayed pipe so that the air heated to a predetermined temperature, circulating in a ring of heat-insulated pipes, heats the inner walls of all pipes until the stationary conditions of heat flows passing through the pipes are reached. In this case, the output of the first flow meter is connected to the input of the readings of the first flow meter of the automatic control and registration unit, the other pair of ends of the bench and tested heat-insulated pipes sealed by two other process thermally insulated couplings and connected by a second flexible thermally insulated pipe installed between the first air flow meter and the second block fans and a heating unit, sequentially installed with the possibility of heating the circulating air flow spirit inside the pipes until they reach a constant temperature. Moreover, the output of the second flow meter is connected to the input of the readings of the second flow meter of the automatic control and registration unit, the third and fourth outputs of which are connected to the control inputs of the second heating unit and the second fan unit, respectively. The achievement of the condition of stationary heat fluxes is judged by the constancy of the readings of air flow temperature sensors located at the inlet and outlet of the test and bench heat-insulated pipes and on their outer surface. The thermotechnical characteristics of the tested pipe are judged by the results of measurements of the ambient temperature, the temperature of the outer surface of the insulated pipe along the entire length, by the temperature difference of the air flow at the inlet and outlet of the studied thermally insulated pipe, and also taking into account the mass air flow.

Each temperature measuring unit may contain a set of air flow temperature measuring sensors installed at the inlet and outlet of the outer surface of the insulated pipe. From the differences in temperature of the air flow obtained from two temperature measuring units, and from the results of measurements of the ambient temperature, the thermal conductivity of the tested pipe is determined.

The thermally insulated pipe under test may consist of at least two pipes connected by a full-size coupling.

As a bench pipe, a reference pipe covered with a layer of thermal insulation with a known coefficient of thermal conductivity can be used.

As a test tube can be used the second test insulated pipe, consisting of at least two fastened full-sized pipe coupling.

Both test pipes along the entire length can be coated with a uniform layer of thermal insulation of constant thickness with a known coefficient of thermal conductivity.

The material from which the walls of the heat-insulated pipe of the oil gauge are made is not a homogeneous material. The design of the walls is such that the properties of the walls of the pipe differ sharply in its length. Therefore, the thermal characteristics measured by the ITP-MG4.03 POTOK device at one point can sharply differ from the results of thermal characteristics measured at another point on the pipe. This is especially true for vacuum insulated elevator tubes.

In figures 1-2 shows options for thermotechnical testing of thermally insulated pipes using the proposed stand. Moreover, the numbering of identical elements of the stand according to the first and second options coincides in figures 1 and 2.

The stand for thermotechnical testing of thermally insulated pipes includes: tested thermally insulated pipe - 1; bench heat-insulated pipe - 2 with a heat-insulating layer - 3. Moreover, the inner diameters of the first and second pipes are equal, and the heat-insulating layer of the pipe 2 shown in Fig. 1 is made of a homogeneous heat-insulating material with a known coefficient of thermal conductivity, which allows us to take it as a reference. The stand includes the first flexible thermally insulated pipe - 4; the second flexible heat-insulated pipe - 5; the first air mass meter - 6; the first block of fans - 7; the first heating unit is 8; the first temperature measuring unit, which consists of the first channel sensor — 9 air temperature, the second channel sensor — 10 air temperature, the first sensor — 11 the external surface temperature of the test pipe, the second sensor — 12 the external surface temperature of the tested pipe, the first sensor — 13 the temperature of the inner surface of the tested pipe, the second sensor - 14 temperature of the inner surface of the tested pipe, the sensor - 15 ambient temperature. The stand also includes: the first technological insulated sleeve - 16; the second technological insulated sleeve - 17; automatic control and registration unit - 18; two full-size couplings - 19, 20, which can be made both with a heat-insulating liner and without it, and designed for hermetic connection of two pipes involved in the distribution of heat fluxes in the radial direction. In addition, the stand contains a second temperature measuring unit, which includes: the third sensor - 21 temperatures of the outer surface of the bench pipe, the fourth sensor - 22 temperatures of the outer surface of the bench pipe, the third sensor - 23 temperatures of the inner surface of the bench pipe, the fourth sensor - 24 temperatures the inner surface of the bench pipe, the third channel sensor 25 air temperature, the fourth channel sensor 26 air temperature, the second flow meter 27; the second heating unit - 28; the second block of fans - 29, the third technological insulated coupling - 30; fourth technological insulated sleeve - 31, layer - 32 additional insulation of the tested insulated pipe, layer - 33 additional insulation of the bench insulated pipe.

The tested thermally insulated pipe of oil grade or an assembly of two such pipes (1) is hermetically connected at one end to the first heating unit (8) and the other to the second flexible thermally insulated pipe (5) using process thermally insulated couplings (16, 17), respectively, which install channel air flow temperature sensors (9, 10).

The bench pipe (2) can be hermetically connected at one end - with a flexible thermally insulated pipe (4), the other - with the second heating unit (28) using technological thermally insulated couplings (30, 31), respectively, on which the third and fourth channel sensors are installed, respectively air flow temperature (25, 26).

The first and second fan blocks (7, 29) and the first and second heating blocks (8, 28) are installed sequentially in the stand, as a result of which air flow begins to circulate in the pipes (1, 5, 2, 4), the steady-state flow rate of which is measured first and second mass flow meters (6, 27).

The fan blocks (7, 29) may contain at least one channel fan. Control actions allowing the switching on and off of the first and second fan blocks are provided respectively from the first and third outputs of the automatic control and registration unit (18).

The installation of the first fan unit (7) and the first heating unit (8) performed on the channel heater, as well as the installation of the second fan unit (29) and the second heating unit (28), performed similarly to the first heating unit, are carried out sequentially. Under the influence of duct fans in the pipes (1, 5, 2, 4), a stream of air begins to circulate, the flow rate of which can be measured by air flow meters (6, 27).

The automatic control and registration unit (18) can be performed on the basis of a computer, the outputs of which are connected to the control inputs for turning on and off the fan units (7, 29) and the heating unit (8, 28), and the inputs for receiving the measured temperature readings of the unit (18) connected through analog-to-digital converters (ADCs) with the first and second temperature measurement units.

The automatic control and registration unit (18) maintains the set airflow temperature based on the readings received from all temperature sensors (9, 10, 11, 12, 13, 14, 21, 22, 23, 24, 25, 26) by controlling the voltage supplied to the heating units (8, 28). Temperature sensors (11, 12) are moved along the outer surface of the test insulated pipe, while at the points of interest temperature is measured on its surface. Temperature sensors (21, 22) are moved along the outer surface of the bench thermally insulated pipe, and also at points of interest temperature measurements are taken on the surface of the bench thermally insulated pipe. These readings are recorded in the automatic control and registration unit.

The automatic control and registration unit (18) continuously monitors changes in the readings of temperature sensors (9, 10, 11, 13, 14, 21, 22, 23, 24, 25, 26) at specified time intervals to determine and supply the required voltage to the heaters, to achieve a stationary thermal regime. Upon reaching the maximum values of the intervals for changing the readings of the mentioned sensors, the block (18) gives signals about the achievement of the stationary heat fluxes in the studied thermally insulated pipe (1), as well as in the stand pipe (2).

The steady-state values of the temperatures Θ _H and измер _K , measured by channel sensors for air temperature (9, 10, 25, 26), and air flow measured by flowmeters (6, 27) are then fixed by an automatic control and registration unit (18).

Obtaining during the test the parameters characterizing the thermophysical properties of the tested thermally insulated pipe and the bench (reference) pipe, compare the obtained parameters of the bench pipe with its certified parameters. If these parameters coincide, it can be judged that the stationary mode was achieved during the tests, as well as the correctness of their conduct, which in turn confirms the accuracy of the data obtained for the tested insulated pipe.

Then turn off the flow meters and channel heaters (6, 8, 27, 28), disconnect the flexible insulated pipes (4, 5) from the flow meters (6, 27), blow the pipe system (1, 5, 2, 4) with “cold” air the temperature of which coincides with the temperature of the room in which the stand is located.

The effective thermal conductivity of a thermally insulated pipe or an assembly of two pipes, as well as a bench pipe, is calculated by the formula:

Where:

D ₁ , D ₂ , L - respectively, the inner, outer diameters and the length of the insulated pipe in meters;

T ₀ ° C - ambient temperature;

Θ _H , Θ _K - air flow temperature at the inlet and outlet of the heat-insulated pipe in C;

With _P , J / kg · K - specific heat of air;

kg / s - mass air flow.

The coefficient of thermal conductivity of the insulation of the bench pipe, which plays the role of the sample, is calculated by the formula

,

Where:

L ^O - respectively, the inner, outer diameters and the length of the bench thermally insulated pipe in meters;

- ambient temperature;

Θ ° _H , Θ ° _K - air flow temperature at the inlet and outlet of the heat-insulated pipe in ° K;

With _P , J / kg · ⁰ K - specific heat of air;

kg / s - air mass flow

The accuracy of measuring the effective thermal conductivity λ _{eff of an} insulated oil pipe of an assortment of oil or an assembly of two such pipes is judged by the degree of coincidence of the homogeneous heat-insulating material measured during the tests of the thermal conductivity λ ₀ with the additional value of the thermal conductivity coefficient known for this material.

After cooling the test thermally insulated pipe of the oil gauge (1), disconnect the process couplings from it (16, 17), dismantle the thermally insulated pipe (1), after which the stand is ready for testing the next thermally insulated pipe of the oil gauge.

An additional technical result provided by the utility model, increasing the efficiency of testing thermally insulated oil pipes of the assortment, can be obtained by installing instead of the bench pipe an assembly of the tested thermally insulated pipes of the oil assortment (as shown in figure 2), covered over the entire length by layers of uniform thermal insulation constant thickness with a known coefficient of thermal conductivity (layer 32 covers the first test pipe (1) and layer 33 - the other test pipe 2). In this case, the measurement of the ambient temperature, the temperature difference of the air flow at the inlet and outlet of each of the assemblies of the tested insulated pipes is carried out at a constant mass flow twice:

- once, when all thermally insulated pipes are covered over the entire length by a layer (32, 33) of uniform thermal insulation of constant thickness with a known coefficient of thermal conductivity (figure 2);

- another time, when all thermally insulated pipes are free from the layer (32, 33) of additional thermal insulation (figure 2), and the thermal conductivity of each of the assemblies of thermally insulated pipes is determined by the measurement results.

The effective thermal conductivity of each of the assemblies of two pipes, free from the layer of additional thermal insulation, is calculated by the formula (1).

The thermal conductivity of the additional insulation layer is calculated by the formula

,

where: D ₃ = (D ₂ + 2δ), (m) is the diameter of the thermally insulated pipe covered with additional thermal insulation of thickness δ;

Θ ^Σ _H , Θ ^Σ _K is the temperature of the air flow at the inlet and at the outlet of the heat-insulated pipe (in ° C), covered by additional thermal insulation;

The accuracy of measuring the effective thermal conductivity λ _{eff of} heat-insulated pipes of the oil gauge is judged by the degree of coincidence of the thermal conductivity coefficient λ _O measured during the tests of the homogeneous heat-insulating material with the reference value of the thermal conductivity coefficient known for this material.

Thus, the proposed design of the stand for thermotechnical testing of thermally insulated pipes allows testing with thermally insulated pipes of oil grade, the length of which is 10-12 m or more. The weight of such a pipe can reach 500 kg or more.

Claims (6)

1. A stand for thermotechnical testing of thermally insulated pipes, comprising at least one thermally insulated pipe to be tested, a first heating unit, a first fan unit, an automatic control and recording unit, a first temperature measuring unit, the outputs of which are connected to the first inputs of receiving the measured temperature readings of the unit automatic control and registration, the first and second outputs of which are connected to the control inputs by turning on the first heating unit and fan unit, respectively, about characterized in that a second temperature measuring unit is introduced into it, the outputs of which are connected to the second inputs of the measured temperature readings of the automatic control and recording unit, the first and second air flow meters, the second fan unit and the heating unit, as well as a bench heat-insulated pipe placed parallel to the test heat-insulated pipe, and one pair of ends of the test and bench heat-insulated pipes are hermetically fixed by means of two technological heat-insulated couplings and is connected by the first flexible insulated pipe installed between the second air flow meter and the first fan unit and the heating unit installed in series, the output of the first flow meter is connected to the input of the testimony of the first flow meter of the automatic control and registration unit, the other pair of ends of the test and stand insulated pipes are hermetically sealed fixed by two other thermally insulated process couplings and connected by a second flexible thermally insulated pipe tained between a first flow meter of air and the second fan unit, and heat set in series, the second flowmeter output connected to an input receiving indications of the second flowmeter automatic control unit and registration, third and fourth outputs of which are connected to switching control inputs of the second block of heat and the second block of the fan, respectively. 2. The stand according to claim 1, characterized in that each temperature measuring unit contains a set of air flow temperature measuring sensors installed at the inlet and outlet of a thermally insulated pipe, the thermal conductivity coefficient of the tested pipe is determined by the differences in air flow temperature and the results of measurements of ambient temperature . 3. The stand according to claim 1, characterized in that the test insulated pipe consists of at least two pipes connected by a full-size coupling. 4. The stand according to claim 1, characterized in that as a bench pipe using a reference pipe, sheathed with a layer of insulation with a known coefficient of thermal conductivity. 5. The stand according to claim 1, characterized in that as the bench pipe use another tested heat-insulated pipe, consisting of at least two fastened full-sized pipe coupling. 6. The stand according to claim 4, characterized in that both test pipes along the entire length are covered with a layer of uniform thermal insulation of constant thickness with a known coefficient of thermal conductivity.