CN115165961A - Gas constant-pressure specific heat capacity measuring device and measuring method thereof - Google Patents
Gas constant-pressure specific heat capacity measuring device and measuring method thereof Download PDFInfo
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Abstract
The application relates to the technical field of measurement and discloses a device and a method for measuring specific heat capacity of gas at constant pressure, wherein the device comprises: a gas line; the heat tracing system is wrapped on the outer wall of the gas pipeline; a first pressure regulator, a thermal flowmeter, a Coriolis flowmeter, and a second pressure regulator are connected in series in the gas pipeline in the gas flow direction. The device is provided with a thermal flowmeter and a Coriolis flowmeter which are connected in series in front and back on a gas pipeline, and can accurately measure the constant pressure specific heat capacity of gas through the combination of the two flowmeters under the control of temperature and pressure of a heat tracing system and a pressure regulator, particularly the constant pressure specific heat capacity of gas mixture with unknown components or compositions, and has the advantages of accurate measurement result, low cost, rapidness and convenience.
Description
Technical Field
The invention relates to the technical field of measurement, in particular to a device and a method for measuring the specific heat capacity of gas at a constant pressure.
Background
The specific heat capacity of a substance is not only an important parameter for describing the thermodynamic property of the substance, but also characteristic data closely related to the structure of the substance, has important significance on scientific research, engineering calculation and thermal analysis, is a basic physical property parameter of the substance and necessary data for carrying out related calculation, and therefore, the measurement of the specific heat capacity of the substance is one of basic thermodynamic measurements. Because the constant-pressure specific heat capacity is most widely applied in engineering and the constant-pressure process is easy to carry out in experiments, the specific heat capacity of the fluid is generally measured by the constant-pressure specific heat capacity.
At present, for gas mixtures with simple pure gas and partial components and known compositions, the specific heat capacity value can be referred to documents, such as physical property handbooks, NIST Chemistry WebBook and the like, and physical property analysis data of Aspen plus; for the constant-pressure specific heat capacity of a gas mixture with complex components and known composition or gas which is not reported in the literature, the specific heat capacity value can only refer to the physical property analysis data of Aspen plus. However, in all the above cases, the precise specific heat capacity value can only be obtained by experimental measurement, and especially for the specific heat capacity of a gas mixture with unknown composition, the value cannot be referred to, and can only be obtained by experimental measurement.
The measurement principle of the specific heat capacity is the same as the specific heat capacity definition in thermodynamics, that is, the heat absorbed or released when a unit mass of a substance changes a unit temperature is measured by a calorimeter. The commercial CALVET (Calvin) 3D specific heat sensor is based on a well-designed micro calorimeter, can realize very high sensitivity and precision for measuring the specific heat capacity of a substance, but is only suitable for measuring the specific heat capacity of liquid and solid and is not suitable for measuring the specific heat capacity of gas.
Therefore, how to accurately measure the specific heat capacity of the gas at the constant pressure is a technical problem to be solved urgently by those skilled in the art.
Disclosure of Invention
In view of this, the present invention provides a device and a method for measuring a specific heat capacity at a constant pressure of a gas, which can accurately measure the specific heat capacity at the constant pressure of the gas. The specific scheme is as follows:
a gas constant-pressure specific heat capacity measuring device comprises:
a gas line;
a heat tracing system wrapped around the outer wall of the gas pipeline;
a first pressure regulator, a thermal flowmeter, a Coriolis flowmeter and a second pressure regulator are connected in series in the gas pipeline in the gas flow direction.
Preferably, in the above gas constant-pressure specific heat capacity measuring apparatus provided in an embodiment of the present invention, the thermal type flow meter includes:
a detection tube connected to the gas line;
the first temperature sensor and the second temperature sensor are positioned at two ends in the detection pipe;
a heater located at the middle position inside the detection tube;
a temperature difference detector connected to the first temperature sensor and the second temperature sensor, respectively;
and the flow transmitter is connected with the temperature difference detector.
Preferably, in the above gas constant-pressure specific heat capacity measuring apparatus provided in the embodiment of the present invention, the coriolis flowmeter includes a flow rate measuring component and a density measuring component.
Preferably, in the device for measuring a specific heat capacity at a constant pressure for gas provided by the embodiment of the present invention, the coriolis flowmeter is a U-shaped vibrating tube coriolis flowmeter.
Preferably, in the above gas constant-pressure specific heat capacity measuring device provided in the embodiment of the present invention, the response time of the thermal flowmeter is less than 0.1 second, and the lower limit of flow detection is 50 mg/hr;
the Coriolis flowmeter has a response time of less than 0.1 second, a lower limit of flow detection of 50 mg/hr, and a lower limit of density detection of 0.3kg m -3 。
Preferably, in the above device for measuring the constant-pressure specific heat capacity of the gas provided by the embodiment of the present invention, the heat tracing system is a system for performing direct or indirect heat exchange with the inside of the pipeline through a heat tracing medium.
The embodiment of the invention also provides a measuring method of the gas constant-pressure specific heat capacity measuring device, which comprises the following steps:
the method comprises the following steps of (1) controlling the temperature of a gas pipeline by adopting a heat tracing system, and controlling the pressure of the gas pipeline by adopting a first pressure regulator and a second pressure regulator;
controlling the measured gas to enter the thermal flow meter and the coriolis flow meter and recording volumetric flow readings of the thermal flow meter and the coriolis flow meter when the measured gas temperature and pressure in the gas line are in a measurement state;
controlling the measured gas to enter the thermal flow meter and the coriolis flow meter and recording a density flow reading of the coriolis flow meter when the measured gas temperature and pressure in the gas line are at a standard state;
and determining the constant pressure specific heat capacity of the measured gas in a measuring state according to the recorded volume flow readings of the thermal flow meter and the Coriolis flow meter and the density flow reading of the Coriolis flow meter.
Preferably, in the measuring method of the gas constant-pressure specific heat capacity measuring device provided by the embodiment of the present invention, the following formula is adopted to determine the constant-pressure specific heat capacity of the measured gas in a measuring state:
wherein, T is the temperature of the measured gas in the measuring state, and P is the pressure of the measured gas in the measuring state; t is a unit of 0 Is the temperature of the measured gas in the standard state, P 0 The pressure of the measured gas in a standard state is measured; c. C p Is the constant pressure specific heat capacity of the measured gas under the measuring state (T, P);
calibrating the thermal flow meter with a calibration gas at (T) 0 ，P 0 ) Standard volumetric flow reading with the lower baseline; q C A volumetric flow reading for the coriolis flow meter; c M The molar constant pressure heat capacity of the calibration gas under the measuring state (T, P); v m Is in a gas standard state (T) 0 ，P 0 ) The molar volume of (a);
is a density reading of the coriolis flow meter.
Preferably, in the measuring method of the above-mentioned constant-pressure specific heat capacity measuring apparatus for a gas, provided by an embodiment of the present invention, the molar constant-pressure heat capacity of the calibration gas in the measurement state (T, P) is obtained by pure component physical property analysis of Aspen Plus.
Preferably, in the measuring method of the device for measuring specific heat capacity at constant pressure of gas provided by the embodiment of the present invention, the response time of the thermal flowmeter is less than 0.1 second, and the lower limit of flow detection is 50 mg/hr;
the Coriolis flowmeter has a response time of less than 0.1 second, a lower limit of flow detection of 50 mg/hr, and a lower limit of density detection of 0.3kg · m -3 。
According to the technical scheme, the device for measuring the constant-pressure specific heat capacity of the gas comprises: a gas line; the heat tracing system is wrapped on the outer wall of the gas pipeline; a first pressure regulator, a thermal flowmeter, a Coriolis flowmeter, and a second pressure regulator are connected in series in the gas pipeline in the gas flow direction.
The gas constant-pressure specific heat capacity measuring device provided by the invention is characterized in that a gas pipeline is connected with a thermal flowmeter and a Coriolis flowmeter in series in the front and at the back, the gas constant-pressure specific heat capacity can be accurately measured through the combination of the two flowmeters under the control of temperature and pressure by a heat tracing system and a pressure regulator, and particularly, the gas constant-pressure specific heat capacity measuring device has the advantages of accurate measurement result, low cost, rapidness and convenience for the measurement of the constant-pressure specific heat capacity of a gas mixture with unknown components or compositions.
In addition, the invention also provides a corresponding measuring method for the gas constant-pressure specific heat capacity measuring device, so that the device has higher practicability, and the measuring method has corresponding advantages.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related arts, the drawings used in the description of the embodiments or the related arts will be briefly introduced below, it is obvious that the drawings in the description below are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a gas constant-pressure specific heat capacity measurement device provided in an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a thermal flowmeter according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a coriolis flow meter according to an embodiment of the present invention;
fig. 4 is a flowchart of a measuring method of the gas constant-pressure specific heat capacity measuring apparatus according to the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The invention provides a gas constant-pressure specific heat capacity measuring device, as shown in figure 1, comprising:
a gas line 1;
a heat tracing system 2 wrapped on the outer wall of the gas pipeline 1;
a first pressure regulator 3, a thermal flow meter 4, a coriolis flow meter 5, and a second pressure regulator 6 are connected in series in the gas flow direction in the gas line 1.
In the gas constant-pressure specific heat capacity measuring device provided by the embodiment of the invention, the gas pipeline 1 is connected with the thermal type flow meter 4 and the Coriolis flow meter 5 in series in front and back, and the gas constant-pressure specific heat capacity can be accurately measured by combining the two flow meters under the control of temperature and pressure of the heat tracing system 2, the first pressure regulator 3 and the second pressure regulator 6, particularly for the measurement of the constant-pressure specific heat capacity of a gas mixture with unknown components or compositions, so that the device has the advantages of accurate measurement result, low cost, rapidness and convenience.
Further, in practical implementation, in the above-mentioned gas constant-pressure specific heat capacity measurement apparatus provided in the embodiment of the present invention, the thermal type flow meter 4 is a device having a flow measurement component, and as shown in fig. 1 and fig. 2, the thermal type flow meter 4 may include:
a detection pipe 41 connected to the gas line 1; the gas A to be tested in the gas pipeline 1 can be input and output from the detection pipe 41;
a first temperature sensor 42 and a second temperature sensor 43 located at both ends inside the sensing tube 41;
a heater 44 located at an intermediate position inside the detection tube 41;
a temperature difference detector 45 connected to the first temperature sensor 42 and the second temperature sensor 43, respectively;
a flow transmitter 46 connected to the temperature difference detector 45.
The thermal flow meter 4 of the present invention has a very short response time and a very high accuracy. Specifically, the response time of thermal flowmeter 4 is less than 0.1 second, the flow measurement error is less than ± 0.15%, and the lower limit of flow detection is 50 mg/hr.
In specific implementation, in the above apparatus for measuring a constant-pressure specific heat capacity of a gas provided in an embodiment of the present invention, the coriolis flowmeter 5 includes a flow measuring component and a density measuring component. The flow rate and density measurement principle of the coriolis flowmeter 5 is as follows: all coriolis flowmeters 5 are based on the principle that when a fluid flows through a vibrating tube, coriolis force proportional to mass flow is generated, and thus high-precision direct mass flow measurement is achieved in the true sense. Preferably, as shown in fig. 3, coriolis flowmeter 5 is a U-shaped vibrating tube coriolis flowmeter.
Fig. 3 shows a schematic diagram of the flow, density measurement and flow control principle of a U-shaped vibrating tube coriolis flowmeter, in which 51 is a U-shaped flow measurement tube, 52 is an electromagnetic sensor, 53 is an electromagnetic detector, 54 is a flow transmitter, 55 is a driver, and 56 is a fluid force. In a U-shaped vibrating tube coriolis flowmeter, the driven measurement tube 51 vibrates up and down in a sinusoidal manner, and the electromagnetic sensor 52 can output a signal representing the sinusoidal motion of the measurement tube 51. When the gas a to be measured passes through the measuring tube 51, coriolis force is generated to deform the front and rear halves of the midpoint of the measuring tube 51 in opposite directions, which results in a time difference Δ t (sinusoidal motion signal phase difference) between the two sensors 52, and when the mass flow rate increases, the degree of deformation of the measuring tube 51 increases, and the time difference between the two sensors 52 increases.
The coriolis flowmeter 5 of the present invention has a short response time and high accuracy. Specifically, the coriolis flowmeter 5 has a response time of less than 0.1 second, a flow measurement error of less than ± 0.15%, a lower limit of flow detection of 50 mg/hr, a density measurement error of less than ± 0.1%, and a lower limit of density detection of 0.3kg · m -3 。
In specific implementation, in the above-mentioned gas constant-pressure specific heat capacity measurement apparatus provided in the embodiment of the present invention, the heat tracing system 2 is a system that directly or indirectly exchanges heat with the inside of the pipeline through a heat tracing medium. The first pressure regulator 3 is a device having a post-regulator pressure regulating assembly. The second pressure regulator 6 is a device having a pre-regulator pressure regulating assembly. In the present invention, the heat tracing system 2 controls the temperature of the gas line 1, and the first pressure regulator 3 before the thermal flow meter 4 and the second pressure regulator 6 after the coriolis flow meter 5 are used in cooperation, thereby maintaining the gas temperature and the gas pressure in the gas line 1 at the set values.
Based on the same inventive concept, the embodiment of the invention also provides a measuring method of the gas constant-pressure specific heat capacity measuring device, and as the principle of solving the problems of the measuring method is similar to that of the gas constant-pressure specific heat capacity measuring device, the implementation of the measuring method can refer to the implementation of the gas constant-pressure specific heat capacity measuring device, and the implementation of the gas constant-pressure specific heat capacity measuring device can also refer to the implementation of the measuring method, and repeated parts are not described again.
In specific implementation, the measurement method of the gas constant-pressure specific heat capacity measurement device provided by the embodiment of the invention, as shown in fig. 4, specifically includes the following steps:
s401, controlling the temperature of the gas pipeline by adopting a heat tracing system, and controlling the pressure of the gas pipeline by adopting a first pressure regulator and a second pressure regulator;
s402, when the temperature and the pressure of the gas to be measured in the gas pipeline are in a measuring state, controlling the gas to be measured to enter the thermal flowmeter and the Coriolis flowmeter, and recording the volume flow readings of the thermal flowmeter and the Coriolis flowmeter;
s403, when the temperature and the pressure of the gas to be measured in the gas pipeline are in a standard state, controlling the gas to be measured to enter the thermal flowmeter and the Coriolis flowmeter, and recording the density flow reading of the Coriolis flowmeter;
and S404, determining the constant-pressure specific heat capacity of the measured gas in the measuring state according to the recorded volume flow readings of the thermal flowmeter and the Coriolis flowmeter and the density flow reading of the Coriolis flowmeter.
In the measuring method of the gas constant-pressure specific heat capacity measuring device provided by the embodiment of the invention, the gas constant-pressure specific heat capacity can be accurately measured by executing the steps S401 to S404, and particularly, the measuring method has the advantages of accurate measuring result, low cost, rapidness and convenience for measuring the constant-pressure specific heat capacity of a gas mixture with unknown components or compositions.
In practical applications, the standard state may be a state where the temperature is 273.15K and the pressure is 101.325 kPa.
Further, in practical implementation, in the measuring method of the gas constant-pressure specific heat capacity measuring apparatus provided by the embodiment of the present invention, when step S404 is executed, the following formula is used to determine the constant-pressure specific heat capacity of the measured gas in the measuring state:
wherein, T is the temperature of the measured gas in the measuring state, and P is the pressure of the measured gas in the measuring state; t is 0 Is the temperature of the measured gas in the standard state, P 0 The pressure of the measured gas in a standard state is measured; c. C p Is the constant pressure specific heat capacity of the measured gas under the measuring state (T, P) and has the unit of J.K -1 ·kg -1 ；
In step S402, the thermal flowmeter uses the calibration gas as (T) 0 ，P 0 ) Standard volumetric flow reading with the lower baseline; q C A volumetric flow reading of the coriolis flow meter at step S402; c M The molar constant pressure heat capacity of the calibration gas in the measured state (T, P) is expressed in J.K -1 ·mol -1 Values which can be obtained by Pure component physical Analysis (Properties-Analysis-Pure Analysis) of Aspen Plus; v m Is in a gas standard state (T) 0 ，P 0 ) The molar volume of (A) is 22.4141 L.mol -1 ；
The density reading of the coriolis flowmeter in g · L at step S403 -1 。
Specifically, taking fig. 2 as an example, the measurement principle of the thermal flowmeter is as follows: when a fluid (such as a gas A to be detected) passes through a section of high-temperature flow channel (such as the detection tube 41) heated by constant power, a temperature difference is generated between the upstream detector and the downstream detector of the flow channel, and a linear relation exists between the product of the heat capacity and the flow speed of the fluid and the temperature difference at two ends of the flow channel, namely:
ΔT＝T 2 -T 1 ＝A·P·c p ·Q m (2)
wherein, delta T is the temperature difference between the two ends of the high-temperature flow channel; c. C p Is the constant pressure specific heat capacity of the gas; p is the heating power of the runner; a is a proportionality constant; q m Is the mass flow rate of the fluid.
When the measured gas is not the calibration gas of the flowmeter, the heat tracing system and the pressure regulator control the temperature and the pressure of the gas pipeline, and the temperature and the pressure of the measured gas in the pipeline are in a measuring state (T, P), the thermal flowmeter has the following flow conversion relation:
wherein (T) 0 ，P 0 ) Is the standard state of gas, the standard state selected by the invention is (273.15K, 101.325kPa);
is that the measured gas is in (T) 0 ，P 0 ) True standard volumetric flow rate;
is a thermal flowmeter for calibrating gas in (T) 0 ，P 0 ) Standard volumetric flow reading with the lower baseline; c is the molar constant pressure heat capacity of the measured gas in the measured state (T, P), C M Is the molar constant pressure heat capacity of the calibration gas in the measured state (T, P).
In the case of the U-shaped vibrating tube coriolis flowmeter shown in fig. 3, the mass flow rate is determined by the following equation:
Q m ＝k·Δt (4)
wherein Q is m For mass flow, k is a flow calibration coefficient, and Δ t is a time difference, so that direct measurement of mass flow is realized. The mass is a constant and is not influenced by factors such as temperature, pressure, viscosity, specific heat capacity and the like, so the measured mass flow is the real mass flow of the gas, the temperature and the pressure are not required to be corrected, and the high-precision mass flow measurement is really realized. At the same time, the measuring tube vibrates at natural frequency, the change of fluid density will cause the mass flow of the fluid to change, and the frequency of the signal output by the detector also changes, and the signal passes throughThe density p of the fluid can be determined by measuring the signal frequency of the detector, and the volume flow Q of the fluid is obtained V . In summary, there are:
Q C ＝Q V(T,P) (5)
wherein Q C Is the volumetric flow reading, Q, of the Coriolis flowmeter V(T,P) Is the true volume flow of the measured gas under the condition of the measuring state (T, P).
When the temperature is not too low (not lower than minus tens of degrees centigrade) and the pressure is not too large (not more than several times the atmospheric pressure), various gases and mixtures thereof can be regarded as approximately ideal gases, so that:
from the formulae (3) and (6), the molar constant pressure heat capacity C of the gas to be measured in the measured state (T, P) can be obtained in J.K -1 ·mol -1 ：
Wherein the content of the first and second substances,
is the ratio of the volumetric flow readings, C, of the thermal flowmeter to the Coriolis flowmeter M The molar constant pressure heat capacity of the calibration gas of the thermal flowmeter in a measuring state (T, P) can be obtained by Pure component physical property Analysis (Properties-Analysis-Pure Analysis) of Aspen Plus.
When the heat tracing system and the pressure regulator control the temperature and the pressure of the gas pipeline, the temperature and the pressure of the gas to be measured in the pipeline are in a standard state (T) 0 ，P 0 ) While the Coriolis flowmeter measures the measured gas (T) 0 ，P 0 ) Lower density
The molar mass of the gas to be measured is:
wherein M is the molar mass of the gas to be measured and has the unit of g.mol -1 ；V m Is a gas standard state (T) 0 ，P 0 ) The molar volume of (A) is 22.4141L. Mol -1 . Thus, the constant pressure specific heat capacity of the measured gas in the measuring state (T, P) comprises:
wherein, c p Is the specific heat capacity at constant pressure of the measured gas under the measuring state (T, P). In summary, the ratio of the volumetric flow readings from the thermal flow meter to the coriolis flow meter
Thermal flowmeter calibrating molar constant pressure heat capacity C of gas under measurement state (T, P) M The measured gas measured by the Coriolis flowmeter is in a standard state (T) 0 ，P 0 ) Lower density
The constant pressure specific heat capacity c of the measured gas under the measuring state (T, P) can be calculated p 。
In specific implementation, in the measuring method of the gas constant-pressure specific heat capacity measuring device provided in the embodiment of the present invention, the response time of the thermal flowmeter is less than 0.1 second, and the lower limit of flow detection is 50 mg/hr; the Coriolis flowmeter has a response time of less than 0.1 second, a lower limit of flow detection of 50 mg/hr, and a lower limit of density detection of 0.3kg · m -3 。
The following describes the measurement result of the gas constant-pressure specific heat capacity measurement device provided by the embodiment of the present invention, taking the measurement of the constant-pressure specific heat capacity of ethylene (the constant-pressure specific heat capacity of ethylene is known) as an example, and the specific steps are as follows:
step one, ethylene passes through the gas constant-pressure specific heat capacity measuring device at a constant flow rate, the temperature and the pressure of a gas pipeline are controlled through a heat tracing system, a first pressure regulator and a second pressure regulator, the gas in the pipeline is at 60 ℃ and 1.5bar, the volume flow reading of a thermal flowmeter is 123.02SLPH (standard liter per hour), the volume flow reading of a Coriolis flowmeter is 63.66 L.h -1 ；
Step two, ethylene passes through the gas constant-pressure specific heat capacity measuring device of the invention at a constant flow rate, the temperature and the pressure of a gas pipeline are controlled through a heat tracing system, a first pressure regulator and a second pressure regulator, the gas in the pipeline is at 0 ℃,101.325kPa, and the density reading of a Coriolis flowmeter is 1.252 g.L -1 ；
Step three, obtaining the thermal flowmeter calibration gas (the thermal flowmeter calibration gas in the invention is nitrogen) by Aspen PlusV11 by adopting NRTL physical property method and pure component physical property analysis, wherein the molar constant pressure heat capacity of the thermal flowmeter calibration gas is 29.1509 J.K at 60 ℃ and 1.5bar -1 ·mol -1 Finally, the specific heat capacity at constant pressure of 1653.86 J.K of ethylene at 60 ℃ and 1.5bar is calculated by the formula (1) -1 ·kg -1 。
Step four, obtaining the constant-pressure specific heat capacity 1655.71 J.K of ethylene at 60 ℃ and 1.5bar by using NRTL physical property method and pure component physical property analysis from Aspen PlusV11 -1 ·kg -1 。
And step five, calculating the measurement relative deviation of the constant pressure specific heat capacity of the ethylene (relative deviation = (the measured value of the method of the invention-Aspen Plus analysis value)/Aspen Plus analysis value), wherein the result is-0.11%, and the high precision of the method for measuring the constant pressure specific heat capacity of the gas is shown.
For more specific working processes of the above steps, reference may be made to corresponding contents disclosed in the foregoing embodiments, and details are not repeated here.
In the present specification, the embodiments are described in a progressive manner, and each embodiment focuses on differences from other embodiments, and the same or similar parts between the embodiments are referred to each other. The method disclosed by the embodiment corresponds to the device disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the device part for description.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
To sum up, the device for measuring the constant-pressure specific heat capacity of the gas provided by the embodiment of the invention comprises: a gas line; the heat tracing system is wrapped on the outer wall of the gas pipeline; a first pressure regulator, a thermal flowmeter, a Coriolis flowmeter, and a second pressure regulator are connected in series in the gas pipeline in the gas flow direction. In the gas constant-pressure specific heat capacity measuring device, the thermal type flowmeter and the Coriolis flowmeter are connected in series in front and back on a gas pipeline, the gas constant-pressure specific heat capacity can be accurately measured through the combination of the two flowmeters under the control of temperature and pressure by the heat tracing system and the pressure regulator, and particularly, the gas constant-pressure specific heat capacity measuring device has the advantages of accurate measuring result, low cost, rapidness and convenience for the measurement of the constant-pressure specific heat capacity of a gas mixture with unknown components or compositions. In addition, the invention also provides a corresponding measuring method for the gas constant-pressure specific heat capacity measuring device, so that the device has higher practicability, and the measuring method has corresponding advantages.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
The gas constant-pressure specific heat capacity measuring device and the measuring method thereof provided by the invention are described in detail, specific examples are applied in the description to explain the principle and the implementation mode of the invention, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. A gas constant-pressure specific heat capacity measuring device is characterized by comprising:
a gas line;
a heat tracing system wrapped around the outer wall of the gas pipeline;
a first pressure regulator, a thermal flowmeter, a Coriolis flowmeter and a second pressure regulator are connected in series in the gas pipeline in the gas flow direction.
2. The gas constant-pressure specific heat capacity measurement device according to claim 1, wherein the thermal type flow meter includes:
a detection tube connected to the gas line;
the first temperature sensor and the second temperature sensor are positioned at two ends in the detection pipe;
a heater located at the middle position inside the detection tube;
a temperature difference detector connected to the first temperature sensor and the second temperature sensor, respectively;
and the flow transmitter is connected with the temperature difference detector.
3. The gas constant-pressure specific heat capacity measurement device according to claim 2, wherein the coriolis flowmeter includes a flow measurement component and a density measurement component.
4. The gas constant-pressure specific heat capacity measurement device according to claim 3, wherein the Coriolis flowmeter is a U-shaped vibrating tube Coriolis flowmeter.
5. The gas constant-pressure specific heat capacity measurement device according to claim 4, wherein the response time of the thermal type flow meter is less than 0.1 second, and the lower detection limit of the flow rate is 50 mg/hr;
the Coriolis flowmeter has a response time of less than 0.1 second, a lower limit of flow detection of 50 mg/hr, and a lower limit of density detection of 0.3kg · m -3 。
6. The gas constant-pressure specific heat capacity measurement device according to claim 1, wherein the heat tracing system is a system for performing direct or indirect heat exchange with the inside of the pipeline through a heat tracing medium.
7. A measuring method of a gas constant-pressure specific heat capacity measuring apparatus according to any one of claims 1 to 6, comprising:
using a heat tracing system to control the temperature of a gas pipeline, and simultaneously using a first pressure regulator and a second pressure regulator to control the pressure of the gas pipeline;
controlling the measured gas to enter the thermal flow meter and the coriolis flow meter and recording volumetric flow readings of the thermal flow meter and the coriolis flow meter when the measured gas temperature and pressure in the gas line are in a measurement state;
controlling the measured gas to enter the thermal flow meter and the coriolis flow meter and recording density flow readings of the coriolis flow meter when the measured gas temperature and pressure in the gas line are at a standard state;
and determining the constant pressure specific heat capacity of the measured gas in a measuring state according to the recorded volume flow readings of the thermal flow meter and the Coriolis flow meter and the density flow reading of the Coriolis flow meter.
8. The measurement method of the gas constant-pressure specific heat capacity measurement device according to claim 7, characterized in that the constant-pressure specific heat capacity of the measured gas in a measurement state is determined by using the following formula:
wherein, T is the temperature of the measured gas in the measuring state, and P is the pressure of the measured gas in the measuring state; t is a unit of 0 Is the temperature of the measured gas in the standard state, P 0 The pressure of the measured gas in a standard state is obtained; c. C p The measured gas is the constant pressure specific heat capacity under the measuring state (T, P);
calibrating the thermal flow meter with a calibration gas at (T) 0 ，P 0 ) Standard volumetric flow reading with the lower baseline; q C A volumetric flow reading for the coriolis flow meter; c M The molar constant pressure heat capacity of the calibration gas in the measuring state (T, P); v m In a gas standard state (T) 0 ，P 0 ) The molar volume of (a);
is a density reading of the coriolis flow meter.
9. The method for measuring a gas constant-pressure specific heat capacity measuring apparatus according to claim 8, wherein the molar constant-pressure heat capacity of the calibration gas in the measurement state (T, P) is obtained by pure component physical property analysis of Aspen Plus.
10. The measurement method of the gas constant-pressure specific heat capacity measurement device according to claim 9, wherein the response time of the thermal type flow meter is less than 0.1 second, and the lower limit of flow detection is 50 mg/hr;
the Coriolis flowmeter has a response time of less than 0.1 second, a lower limit of flow detection of 50 mg/hr, and a lower limit of density detection of 0.3kg m -3 。
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