Correction Method for Lost Heat Flow in Data Processing of Chemical Reaction Calorimetry Experiments

Abstract

The present invention discloses a method for correcting lost heat flow in the processing of chemical reaction calorimetry experimental data. The present invention performs post-processing on the chemical reaction calorimetry experimental data obtained by using an automatic reaction calorimeter. In the process of thermodynamic parameter calibration, the correction point of lost heat flow is identified and set, and the heat loss reference temperature difference corresponding to the correction point is calculated. At the same time, a set of logic for expressing lost heat flow based on the heat loss reference temperature difference is created. In the actual process, by adjusting the heat loss correction point and the heat loss reference temperature difference, a new heat loss baseline is obtained, and then the lost heat flow is calculated, forming a complete analysis and calculation process. The present invention can obtain a benchmark for lost heat flow through actual measurement, and adjust the heat loss correction point of the heat loss reference temperature difference according to the reaction characteristics, so as to obtain a reasonable heat loss baseline value and improve the accuracy and reliability of thermodynamic parameter calibration.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical reaction safety testing, and relates to a method for correcting lost heat flow in chemical reaction calorimetric experiment data processing. Background Art

[0002] An automated reaction calorimeter is an instrument that simulates semi-batch reaction processes in a kettle under laboratory conditions. During the process steps, the calorimeter measures changes in the sample temperature and feed mass in real time, and calculates information such as the heat of reaction, providing a basis for reaction safety risk assessment, process development, and optimization.

[0003] The heat balance in the reactor is an important basis for calculating the heat release of the reaction. The formula for calculating the heat release using the data obtained by the automatic reaction calorimeter is derived from the derivation of the system heat balance, as shown below:

[0004] (1)

[0005] The principle structure of the automatic reaction calorimeter and the heat transfer of the reactor sample are as follows Figure 1 As shown. Among them, Q r Indicates the real-time reaction heat release rate of sample 1 to be measured, Q flow is the heat flow from sample 1 to jacket 3, and its expression is Q flow =UA( ), is the temperature of sample 1 in the reactor, is the temperature of the jacket 3, both of which are obtained by the temperature sensor 4, Q acc It is the heat accumulation of the reactor 2, the liquid feeding device 9 or the stirring blade 8, which is reflected in the temperature change. loss The heat loss in the reactor 2 is caused by the heat flow being conducted to the surrounding air through the phase change convection, the kettle cover 7, the stirring rod 5 inserted into the reactor, the correction heater 6 and the material feeding device 9. Q dos is the heat flow lost when passing through the material feeding device 9, Q c is the thermal power released by the calibration heater 6 of the reaction calorimeter.

[0006] In order to obtain the real-time reaction exothermic rate Q r , it is necessary to obtain the thermodynamic parameters of the reaction process, which are the heat transfer coefficient (UA) and the system heat capacity ( ), the conventional method is to perform static calibration of thermodynamic parameters before and after the reaction. Static calibration is performed before and after the reaction, using a ramping temperature method. The implementation process is as follows:

[0007] (1) By controlling the system of the automatic reaction calorimeter, set isothermal or constant temperature control to achieve a constant thermal equilibrium between the sample temperature and the jacket temperature in the reaction calorimeter and maintain it for more than five minutes, such as Figure 2 The position from t0 to t1 in the equation is called the pre-thermal equilibrium state;

[0008] (2) Introduce a calibration heater to raise the sample temperature by 1.5°C and then remove the calibration heater. Figure 2 middle t1 to t2 position;

[0009] (3) After removing the calibration heater, wait for the reaction calorimeter system to cool down and return to thermal equilibrium for more than five minutes. Figure 2 The position from t3 to t4 is called the post-thermal equilibrium state;

[0010] (4) The heat transfer coefficient (UA) is calculated from t0 to t4 using the following formula:

[0011] (2)

[0012] (5) In the interval from t2 to t4, the system heat capacity is obtained by the following formula ( );

[0013] (3)

[0014] In order to realize the temperature rise and fall calibration, a process jump step operation is required, such as Figure 2 Step 1, step 2 and step 3 in , that is, the interval from step 1 to step 3 is called a complete calibration process, such as Figure 2 shown.

[0015] To obtain the correct heat transfer coefficient (UA) and system heat capacity ( ), loss heat flow Q loss The calculation of Q is particularly important. loss That is, the calculation link targeted by the present invention reflects the energy lost by the heat flow in the reactor through phase change convection through the kettle cover and through the insert in the reactor to the surrounding air through conduction, that is, the lost heat flow.

[0016] The analysis software and related calculation methods of current commercial automatic reaction calorimeters do not clearly specify the loss heat flow Q loss Some software estimates the loss heat flow by artificially setting the heat loss coefficient, which obviously lacks scientific basis. Although the real-time value of the loss heat flow may not be high, this heat loss always exists during the calibration process. Q in formula (2) and formula (3) loss The integral of the reaction calorimeter heat transfer coefficient (UA) and the system heat capacity ( ) parameter calibration has a significant impact on the final result. This is mainly because during the calibration process, due to complex factors such as sudden changes in sample temperature or improper operation, coupled with the lack of a suitable reference measurement point to characterize the degree of heat loss, it becomes difficult to analyze the phenomenon of heat loss. If the integration interval is calculated by simply using the determined average heat loss reference temperature difference or simple linear interpolation as the calculated value, the heat transfer coefficient (UA) and system heat capacity ( ) parameter, so it is necessary to adjust Q according to the actual situation in the integral interval of formula (2) and formula (3) loss Make reasonable corrections. Summary of the Invention

[0017] Based on the above background issues, the present invention proposes a method for correcting lost heat flow in chemical reaction calorimetry experiment data processing.

[0018] A first aspect of the present invention provides a method for correcting heat loss in chemical reaction calorimetry experimental data processing, comprising the following steps:

[0019] Step (1) setting isothermal or constant temperature control for the reaction calorimeter, and implementing a complete calibration process by using a ramping temperature method;

[0020] Step (2) obtaining the heat loss reference temperature difference and loss heat flow in the thermal equilibrium state;

[0021] Step (3) identifying and setting the heat loss correction point;

[0022] Step (4) calculating the heat loss reference temperature difference corresponding to the heat loss correction point;

[0023] Step (5) linear interpolation is performed between any two correction points to obtain the heat loss baseline of the calibration process;

[0024] Step (6) adjusting the position of the heat loss correction point or the heat loss reference temperature difference value, re-interpolating and correcting the heat loss reference temperature difference value to obtain a new heat loss baseline;

[0025] Step (7) calculates the loss heat flux during the calibration process based on the obtained heat loss baseline.

[0026] A second aspect of the present invention provides a computer-readable storage medium having program instructions stored thereon, wherein the program instructions implement the above method when executed.

[0027] A third aspect of the present invention provides a computer program product, comprising a computer program / instruction, which implements the above method when executed by a processor.

[0028] The beneficial effects of the present invention are as follows: the present invention adopts a temperature rise and fall method to realize a complete calibration process, obtains the thermal equilibrium state before and after the calibration process, and uses the temperature difference between the sample and the average temperature of the jacket in this state to characterize the reference value of the loss heat flow. In the calibration process, the heat loss reference temperature difference value is reasonably interpolated in combination with the actual operation and the calibration curve, so as to obtain the heat loss baseline of the calibration process. The heat loss correction point and the heat loss reference temperature difference value can be adjusted in the thermodynamic parameter calibration process to obtain a new heat loss baseline, obtain an accurate heat flow loss value, and thus make the thermodynamic parameter calculation results more scientific. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The schematic diagram of the principle structure of the automatic reaction calorimeter and the heat transfer of the reactor sample;

[0030] Figure 2 A schematic diagram of a complete calibration process;

[0031] Figure 3 This is the calculation flow chart of heat loss in thermodynamic parameter calibration;

[0032] Figure 4 An example of the calibration process of thermodynamic parameters for a calorimetric reaction;

[0033] Figure 5 An example of obtaining heat loss baseline and thermodynamic parameter values ​​by performing simple operations on heat loss correction points;

[0034] Figure 6 This is an example of the heat loss reference temperature difference and thermodynamic parameter changes obtained by using the heat loss flow correction method of this application. DETAILED DESCRIPTION

[0035] The following is a further description of this application in conjunction with the accompanying drawings.

[0036] like Figure 3 As shown, the embodiment of the present application provides a method for correcting lost heat flow in chemical reaction calorimetry experiment data processing, comprising the following steps:

[0037] (1) Implement a complete calibration process

[0038] The reaction calorimeter is set to isothermal or constant temperature control so that the sample temperature and the jacket temperature in the reaction calorimeter reach a constant thermal equilibrium state. A calibration heater is introduced to make the system go through a temperature increase process. After the calibration heater is removed, the thermal equilibrium state is restored to achieve a complete calibration process.

[0039] (2) Obtaining the heat loss reference temperature difference and loss heat flow in the thermal equilibrium state

[0040] In the thermal equilibrium state before the calibration process, find a five-minute reference interval from the position where the calibration heater is introduced to the next process jump step;

[0041] In the thermal equilibrium state after the calibration process, find a five-minute reference interval from the position where the calibration heater is evacuated to the next process jump step;

[0042] Calculate the average values ​​of sample temperature and jacket temperature T in these two intervals respectively r_B and T j_B , the difference between the two is ΔT B It is called the heat loss reference temperature difference, and the subscript B is used to indicate that the automatic reaction calorimeter is in thermal equilibrium.

[0043] In the thermal equilibrium state and according to the formula (1) described in the background technology, Q r , Q acc and Q c is zero, only the heat flow Q is exchanged between the jacket medium and the sample flow The heat loss Q from the sample to the environment loss Balance, that is

[0044] (4)

[0045] The heat loss Q calculated at this time loss This accurately represents the heat loss at the reference point in the reference state when the automatic reaction calorimeter system remains unchanged. The heat loss reference temperature difference can represent the heat loss in a one-to-one correspondence, so the heat loss reference temperature difference is used below to interpolate the heat loss change during the calibration process.

[0046] Furthermore, in the thermal equilibrium state before and after the calibration process, the heat loss reference temperature difference between the thermal equilibrium state reference points before and after can be obtained respectively:

[0047] (5)

[0048] (6)

[0049] The subscript f represents the thermal equilibrium state before calibration, and b represents the thermal equilibrium state after calibration. The corresponding heat loss reference temperature difference values ​​are called the front heat loss reference temperature difference value and the back heat loss reference temperature difference value, respectively.

[0050] (3) Identify and set the heat loss correction point during the calibration process

[0051] Go through the entire calibration process and identify and set the points that meet one of the following conditions as heat loss correction points:

[0052] The first type of correction point: the middle point of the five-minute reference interval before and after the thermal equilibrium state of the calibration process;

[0053] The second type of correction point: the operating point of the evacuation correction heater;

[0054] The third type of correction point: process jump step operation point;

[0055] The fourth type of correction point: the point where the sample change rate exceeds a certain set value.

[0056] (4) Calculate the heat loss reference temperature difference at the heat loss correction point during the calibration process

[0057] After identifying and setting all heat loss correction points, the heat loss reference temperature difference value for each correction point can be obtained as follows:

[0058] The midpoint of the five-minute reference interval between the thermal equilibrium state before and after the calibration process. The actual temperature difference between the sample and the jacket at this moment is used as the heat loss reference temperature difference value at this moment;

[0059] The process jump step operation point correction point, at this moment, the actual temperature difference between the sample and the jacket in the nearest thermal equilibrium state is taken as the heat loss reference temperature difference value at this moment;

[0060] The heat loss reference temperature difference between the operating point where the correction heater is introduced and removed and the heat loss correction point where the sample temperature change rate meets the set value is calculated as follows:

[0061] (7)

[0062] in, It is the heat loss reference temperature difference value of the heat loss correction point in the thermal equilibrium state before the calibration process. It is the heat loss reference temperature difference value of the heat loss correction point in the thermal equilibrium state after the calibration process. and The sample temperature in thermal equilibrium before and after the calibration process, and are the heat loss reference temperature difference and sample temperature of the nth heat loss correction point respectively.

[0063] (5) Calculate the heat loss baseline during the calibration process

[0064] After identifying and setting the heat loss correction points, the heat loss correction points or heat loss reference temperature difference values ​​can be calculated or manually adjusted. The manual adjustment methods for various heat loss correction points are detailed in step (6). After all correction points are identified and set or manually adjusted, and the heat loss reference temperature difference values ​​corresponding to the correction points are calculated or manually adjusted, linear interpolation is performed between each correction point to obtain the heat loss baseline for the calibration process.

[0065] In one embodiment, the heat loss baseline calculation formula is as follows:

[0066] (8)

[0067] Where ΔT B_n Indicates the heat loss reference temperature difference of the current heat loss correction point in the interpolation segment, ΔT B_n+1 It represents the heat loss reference temperature difference of the heat loss correction point after the interpolation segment, n represents the length between the two interpolation heat loss correction points, and i represents the real-time interval length between the two heat loss correction points between the interpolation segment and the previous heat loss correction point.

[0068] Figure 4 is the thermodynamic parameters at a certain time, namely, the heat transfer coefficient (UA) and the system heat capacity ( ) An example of a calibration curve during the calibration process, where Tr represents the sample temperature, Tj represents the jacket temperature, and Pc represents the fixed power output of the calibration heater.

[0069] The thermodynamic parameters described in this application refer to the heat transfer coefficient (UA) and the system heat capacity ( ) two thermodynamic parameters, the heat transfer coefficient (UA) refers to the heat transfer factor between the jacket circulating oil bath and the sample in the reactor; the system heat capacity ( ) refers to the heat capacity of the sample contained in the reactor and the heat capacity of the inserted components such as the sensor, stirring paddle and calibration heater. The latter is called the residual heat capacity.

[0070] Figure 5 Without using the heat loss correction method of this embodiment, the sample temperature and the jacket temperature in the reaction calorimeter did not reach a constant thermal equilibrium state, resulting in the loss of the pre-thermal equilibrium state, which led to the acquisition of incorrect thermodynamic parameters, namely the heat transfer coefficient (UA) and the system heat capacity ( ). Figure 6 To utilize the heat loss flow correction method of this embodiment, all correction points are identified and set, and an example of the change in the heat loss reference temperature difference value obtained after modifying the position of the first correction point is shown.

[0071] (6) Manually adjust various heat loss correction points during the calibration process

[0072] Identify the midpoints of the five-minute reference intervals before and after the thermal equilibrium state during the calibration process, the operating points of introducing and withdrawing the calibration heater according to the calibration, the process jump step operation, and the points where the sample change rate exceeds a certain set value, and set these points as heat loss correction points.

[0073] After identifying and setting the heat loss correction points and their heat loss reference temperature difference values ​​for the entire calibration process in the previous step, professional operators such as process operators and evaluators can manually modify the interactive interface to adjust the heat loss correction points based on the actual calibration response and experimental experience. For example, the lack of a pre-thermal equilibrium state during the calibration process due to operation or other factors may significantly affect the heat loss flow from the sample to the environment. Professional operators can and should only make the following adjustments:

[0074] Modify the heat loss reference temperature difference value of the identified and set heat loss correction point. The heat loss reference temperature difference value that has not been modified is calculated according to formula (8) in step (5). After modification, the modified heat loss reference temperature difference value is directly used.

[0075] Delete the heat loss correction points where the sample change rate exceeds a certain set value and the operating points of the introduction and withdrawal correction heaters. The deleted heat loss correction points will not participate in the interpolation calculation.

[0076] After manual adjustment, the new heat loss correction point and its heat loss baseline temperature difference will be re-interpolated to obtain a new heat loss baseline.

[0077] (7) Based on the obtained heat loss baseline, the heat loss flux during the calibration process is calculated using formula (4).

[0078] By using the correction method of the present application, the heat loss reference temperature difference can be adjusted between each heat loss correction point. Interpolation is performed to obtain the heat loss baseline of the calibration process, and then the loss heat flow is calculated.

[0079] Based on the same concept as the above method, an embodiment of the present application further provides a computer-readable storage medium having program instructions stored thereon, which implement the above method when the program instructions are executed.

[0080] Based on the same concept as the above method, an embodiment of the present application also provides a computer program product, including a computer program / instruction, which implements the above method when executed by a processor.

[0081] The above embodiments further illustrate the purpose, technical solutions and advantages of the present invention in detail. It should be understood that the above embodiments are only preferred implementation plans of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The method for correcting heat loss in chemical reaction calorimetry experimental data processing is characterized by The method comprises the following steps: Step (1) setting isothermal or constant temperature control on the reaction calorimeter so that the sample temperature and the jacket temperature in the reaction calorimeter reach a constant thermal equilibrium state, and using a temperature ramp method to achieve a complete thermodynamic parameter calibration process, wherein the thermodynamic parameters refer to the heat transfer coefficient and the system heat capacity; the temperature ramp method refers to introducing a correction heater to cause the system to undergo a temperature ramp process, and then removing the correction heater to restore the thermal equilibrium state; Step (2) obtaining a heat loss reference temperature difference and a heat loss flow in a thermal equilibrium state, wherein the heat loss flow is the heat loss flow dissipated from the reactor to the surrounding air; Step (3) identifying and setting a heat loss correction point; Step (4) calculating the heat loss reference temperature difference value corresponding to the heat loss correction point; Step (5) linear interpolation is performed between the two correction points to obtain a heat loss baseline for the calibration process; Step (6) adjusting the position of the heat loss correction point or the heat loss reference temperature difference, re-interpolating and correcting the heat loss reference temperature difference to obtain a new heat loss baseline; Step (7) calculating the loss heat flux during the calibration process based on the obtained heat loss baseline; The process of obtaining the heat loss reference temperature difference in step (2) is as follows: In the thermal equilibrium state before and after the calibration process, a five-minute reference interval is searched from the position where the calibration heater is introduced to the next process jump step; In the thermal equilibrium state after the calibration process, the time period from the position where the calibration heater is evacuated to the next process jump step is a five-minute reference interval; Calculate the average values ​​of the sample temperature and jacket temperature in the two intervals respectively, and the difference between the two is the heat loss reference temperature difference; Wherein, step (3) is specifically: The first type of correction point: the middle point of the reference interval in the thermal equilibrium state before and after the calibration process; The second type of correction point: the operating point of the introduction and withdrawal correction heater; The third type of correction point: process jump step operation point; The fourth type of correction point: the point where the sample temperature change rate meets the set value; Among them, in step (4), for the second type correction point and the fourth type correction point, the heat loss reference temperature difference corresponding to the point is calculated as follows: Where, ΔT Bb is the heat loss reference temperature difference of the heat loss correction point in the thermal equilibrium state before the calibration process, ΔT Bf is the heat loss reference temperature difference of the heat loss correction point in the thermal equilibrium state after the calibration process, T rb and T rf are the sample temperatures in thermal equilibrium before and after the calibration process, T rn is the sample temperature corresponding to the nth heat loss correction point.

2. The correction method according to claim 1, wherein: It also includes using the heat loss reference temperature difference value to interpolate the loss heat flow change in the calibration process.

3. The correction method according to claim 1, wherein: For the first type of correction point in step (4): the actual temperature difference between the sample and the jacket at the moment of the point is used as the heat loss reference temperature difference value of the heat loss correction point.

4. The correction method according to claim 1, wherein: In step (4), for the third type of correction point: the actual temperature difference between the sample and the jacket in the thermal equilibrium state at the time of the point is used as the heat loss reference temperature difference value of the heat loss correction point; 5. The correction method according to claim 1, wherein: The adjustment process in step (6) includes: Modify the heat loss reference temperature difference value of the identified and set heat loss correction point; Delete the heat loss correction points where the sample rate of change exceeds the set value and the operating points where the correction heater is introduced and removed.

6. A computer-readable storage medium, characterized in that Program instructions are stored thereon, and when the program instructions are executed, the method according to any one of claims 1 to 5 is implemented.

7. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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