JPH0464011B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a temperature-compensated flow rate measuring device used, for example, in oil depots, oil refineries, and the like. [Prior Art] If the flow rate measuring device is of a volumetric type, the volume of the fluid to be measured changes depending on the temperature, resulting in errors. Conventional temperature-compensated flow measurement devices connect the output shaft of the flowmeter to an integrated flow rate display meter via a micro-transmission, and adjust the speed of the micro-transmission using a bellows that converts temperature changes in the fluid into mechanical displacement. By doing so, the temperature-corrected flow rate is integrated on the display meter. By the way, the volume change due to temperature change of crude oil and petroleum products is determined by JIS K.
2249, it changes not only due to temperature changes but also due to the specific gravity of the fluid, so it is not possible to accurately compensate for temperature with conventional mechanical types, and as a result, it is difficult to accurately measure the flow rate. It wasn't enough to do that. In recent years, with the development of electronic devices, there has been known a technique for storing temperature correction coefficient data and proportionally distributing temperature correction coefficient data for intermediate values. However, the above
The volumetric coefficient table specified in JIS K 2249 is enormous, and storing all of this data requires a storage means with an enormous storage capacity. Further, since this volume conversion coefficient difference requires up to four decimal places, a storage capacity up to that number of digits is required, resulting in a considerable amount of storage capacity. [Problems to be Solved] Therefore, an object of the present invention is to provide a flow rate measuring device with temperature correction that can measure a flow rate that is accurately corrected according to the specific gravity and temperature of the fluid to be measured, even if the storage capacity of the storage means is at least is to provide. [Means for Solving the Problems] According to the flow rate measuring device with temperature correction of the present invention, a flow rate signal transmitter provided in a flow meter, a temperature measuring device for measuring the temperature of the fluid, and a specific gravity setting for setting the specific gravity of the fluid are provided. a storage means for storing a temperature correction coefficient of the fluid corresponding to the temperature and specific gravity, and a control device for calculating a temperature-corrected flow rate value, wherein the temperature correction coefficient stored in the storage means is a predetermined value. The difference in volume conversion coefficients for each specific interval of temperature is multiplied by 10000 based on the volume conversion coefficient corresponding to each specific gravity at a specific interval at a temperature of Based on the temperature correction coefficient stored according to the specific gravity set by the specific gravity setting device, the volume conversion coefficient of the set specific gravity at the measurement temperature is calculated using the formula [(volume conversion coefficient of reference temperature) -
{(sum of temperature correction coefficients between measured temperatures)/(10000)}]
If the measured temperature and set specific gravity are intermediate values between the memorized temperature and specific gravity, they are calculated by proportional distribution based on the above calculation formula, and the flow rate signal is calculated from the flow rate signal generator. A temperature-corrected flow rate value is calculated using a volume conversion coefficient. [Description of effects] Therefore, the storage means stores temperature correction coefficients at specific intervals of temperature (for example, 5°C) and also stores specific gravity values at specific intervals (for example, 0.03 g/cc). However, since the temperature correction coefficient is a value obtained by multiplying the difference in the JIS volume conversion coefficient for the temperature at a specific interval by 10,000, the number of digits is about 2, and therefore the storage volume can be reduced. In other words, simply calculating the difference requires up to four decimal places, resulting in a large number of digits, but since the difference between specific intervals is relatively small, multiplying by 10,000 yields about two digits. As for the specific gravity, the type of oil to be measured is fixed, so set it in advance using a specific gravity setting device.
If the set specific gravity is an intermediate value of the stored specific gravity, the temperature correction coefficient is distributed proportionally. As stipulated in JIS, this proportional allocation is accurate. and JIS at the reference signal (e.g. -25℃)
The volume conversion coefficient of is memorized in advance. Then, since the difference between the temperature of the fluid and the reference signal mentioned above is known, add the temperature correction coefficient that is 10000 times the difference in the JIS volume conversion coefficient mentioned above, and divide that value by 10000. The difference in volume conversion coefficients is determined. Regarding this temperature as well, it is sufficient to calculate the intermediate value by proportional distribution. As described above, according to the present invention, the temperature correction coefficient is a value obtained by multiplying the difference in the volume conversion coefficient for each temperature at a specific interval by 10,000 based on the JIS volume conversion coefficient of the reference temperature,
Since this temperature correction coefficient was stored in the storage means,
The storage capacity can be reduced, and moreover, an accurate flow rate can be determined by proportional distribution.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a temperature-compensated flow rate measuring device according to the present invention, between oil supply pipes 1A and 1B provided between an oil storage tank (not shown) and a discharge nozzle (also not shown). A connecting pipe 1C equipped with a flow rate measuring device (described later) is flange-connected to the connecting pipe 1C, and a flow meter 2 that measures the flow rate of oil flowing inside the pipe and a temperature measuring device that measures the temperature of the oil are connected to the connecting pipe 1C. A sensor 3 is provided. A flow rate pulse transmitter 4 which is a flow rate signal transmitter driven by the flow meter 2 is provided, and the flow rate signal from the flow rate pulse transmitter 4 is inputted to the control device 5 as a pulse signal. Also temperature sensor 3
Similarly, a temperature signal from the controller 5 is input to the control device 5. As mentioned above, the control device 5 stores in advance the values for temperature and specific gravity at specific intervals from the volume conversion coefficient table defined in JIS K 2249, but the values (referred to as temperature correction coefficients) are stored in advance. This will be explained later. Further, as will be described later, the specific gravity of the oil to be measured is input to the control device 5 using the setting dial 6. When the oil flows, the control device 5 calculates a temperature correction coefficient based on the temperature signal from the temperature sensor 3 and the specific gravity input earlier. Further, the flow rate temperature-corrected using the flow rate signal from the flow rate pulse transmitter 4 and the temperature correction coefficient is calculated by the control device 5 as described later, and the integrated flow rate is displayed on the display meter 9, and is also transmitted to the batch counter 7, etc. (not shown). It's becoming like that. The flow rate pulse transmitter 4, the control device 5, and the display meter 9 are housed in an explosion-proof box 11. FIG. 2 shows an example of a control device 5 implemented in the present invention. In the figure, signals from a specific gravity setting dial 6, a temperature sensor 3, and a flow rate pulse transmitter 4 are sent to an input/output device 51. device 51
sends and receives signals to and from the central control unit 52. This central control unit 52 receives signals from a timer 53 and also exchanges signals with a storage means (ROM) 54 and a temporary storage means (RAM) 55. As will be described later, this storage means 54 has a storage section for storing temperature correction coefficients that are obtained by multiplying the difference in volume conversion for each specific interval of temperature by 10,000 based on the JIS volume conversion coefficient corresponding to each specific gravity at specific intervals at a predetermined temperature. 54a and
Storage unit 5 for calculation formulas for performing calculations in the manner described below
4b and a predetermined program 54c. Further, the temporary storage means 55 includes a temporary storage section 55a that stores a temperature correction coefficient, and a remaining amount storage section 55b that stores a fraction of a unit amount in a manner described later. The JIS volume conversion factor table is 0.005 for specific gravity.
It is determined in units of g/cc and temperature in units of 0.5°C. However, as mentioned above, this requires a huge amount of storage, so when implementing the present invention, for example, as shown in the table below, the data storage section 54a stores information about specific gravity at specific intervals of 0.03 g/cc.
Regarding the temperature, it is sufficient to memorize it at specific intervals of 5°C.

[Table] In this table, the volume conversion coefficient is based on a temperature of -25°C, and 10,000 times the coefficient difference for each 5°C difference is stored as a temperature correction coefficient. For example, specific gravity
The difference in the temperature correction coefficient between the oil temperature of 5℃ and 10℃ of 0.78 (indicated at 10℃ in the table above) is 49, which means that the difference in the JIS volume conversion coefficient is 0.0049. ing. Next, embodiments of the present invention will be described with reference mainly to FIGS. 3A and 3B. FIG. 3A is a flowchart for calculating the temperature correction coefficient. First, the central control section 52 reads the specific gravity set on the specific gravity setting dial 6 (step S1). Now, assume that the setting value is, for example, 0.825. Next, the temperature of the temperature sensor 3 is read (step S2). Now, let us assume that the temperature is, for example, 22°C. Next, the central control unit 52
Calculation formula stored in b [(Volume conversion coefficient of reference temperature) - {(sum of temperature correction coefficients between measured temperatures)/
(10000)}], a temperature correction coefficient is calculated (step S3). The calculation is as follows. (1) Find the volume conversion coefficient for a specific gravity of 0.81 and a temperature of 20°C (calculated based on -25°C). 1.0353−Σ20/10000=0.9956 Here, Σ20 is the total value of the difference up to 20°C in the table. (2) Find the volume conversion coefficient for a specific gravity of 0.81 and a temperature of 25℃. 1.0353−Σ25/10000=0.9912 Here, Σ25 is the total value of the difference up to 25°C in the table. (3) Find the volume conversion coefficient for a specific gravity of 0.84 and a temperature of 20℃. 1.0329−Σ20/1000=0.9959 (4) Find the volume conversion coefficient for a specific gravity of 0.84 and a temperature of 25°C. 1.0329−Σ25/10000=0.9918 (5) Find the volume conversion coefficient for a specific gravity of 0.81 and a temperature of 22°C using the specific gravity distribution. 0.9956 - (0.9956 - 0.9912) × (2/5) = 0.9938 (6) Find the volume conversion coefficient for a specific gravity of 0.84 and a temperature of 22°C by proportional distribution. 0.9959−(0.9959−0.9918) ×(2/5)=0.9943 (7) Based on the values of (5) and (6) above, calculate the specific weight by proportional allocation.
Find the volume conversion factor of 0.825 and a temperature of 22℃. 0.9938+{(0.9943−0.9938)×(0.825−0.81)}/(0.84−0.81) =0.9941 Since this value 0.9941 is the volume conversion coefficient, it is stored in the temporary storage section 55a of the temporary storage device 55 (step S4). In this way, the volume conversion coefficient is calculated,
The temperature change of the fluid is not very drastic, and judging from the time constant of the temperature sensor, this flow is
Repeating every 3 seconds is sufficient. Note that in the calculations in (5), (6), and (7) above, the temperature (22°C) was first determined by proportional distribution and then the specific gravity was calculated, but it is also possible to calculate the temperature after determining the specific gravity. Next, referring to FIG.
A preferred embodiment of the relationship for displaying the integrated flow rate will be described. That is, although the display meter 9 is displayed by integer pulses, a fraction is generated due to the above calculation. Figure 3B shows a preferred example of rounding. When a pulse (for example, 0.1) is input from the flow rate pulse generator 4 of the flow meter 2 (step S5). This flow rate input is processed by a so-called interrupt signal, and the central processing unit 52 calculates a temperature-corrected flow rate value (0.9941×0.1=0.09941) from the volume conversion coefficient (0.9941) stored in the temporary storage unit 55a and the pulse. (step S6), and is added to the remaining amount value in the remaining amount storage section 55b of the temporary storage means 55 (for example, if the remaining amount is
If it is 0.05432, then 0.05432+0.09941=
0.15373) (step S7). This added value is compared with the unit amount (for example, 0.1) (step S8), and if the added value is greater than the unit amount, 1 pulse (flow rate
0.1) (step S9), and the display 9 and batch counter 7 integrate one pulse (0.1).
Next, the unit amount is subtracted from the added value (0.15373−0.1=0.05373), and the remaining amount is stored in the remaining amount storage section 5.
5b (step S10). In step S8, if the added value is less than the unit amount, the process returns without outputting a pulse to the display meter. Repeat this process below. Therefore, the control device performs calculations below the unit amount, and only when the unit amount is exceeded does it output one pulse, thereby moving the display meter 9 and the like. Next, another embodiment will be described with reference to FIG. In the embodiment shown in Fig. 3, the set specific gravity is read every time, but in this embodiment, the set specific gravity is read only when starting flow rate measurement. Prior to starting flow rate measurement, when the flow rate measuring device is turned on (step S11), the set specific gravity is read (step S12). Next, the central processing section 52 calculates the volume conversion coefficient for each temperature of the set specific gravity by the same calculation as described above (step S13), and stores this data in the temporary storage section 55a of the temporary storage means 55 (step S14). ). In this way, the volume conversion coefficient for each temperature of the set specific gravity is calculated and stored in advance. Next, as shown in FIG. 4B, the temperature of the temperature sensor 3 is read (step S15), the volume conversion coefficient corresponding to the temperature stored in the temporary storage section 55a is calculated (step S16), and the volume conversion coefficient is calculated. The coefficients are stored in the temporary storage section 55a (step S17). When a flow rate pulse is input from the flow rate pulse transmitter 4 of the flow meter 2, the flow rate calculation process is performed according to the flow shown in FIG. 3B. [Effects of the Invention] As described above, the present invention provides the following excellent effects. (1) Since the number to be stored in the storage means only needs to be two digits and can be stored at specific intervals, the storage capacity of the storage means can be reduced. (2) It is accurate because it is calculated by proportional allocation for numerical values between specific intervals. (3) Therefore, there is no need to memorize a huge number of JIS volume conversion coefficients, and since the storage capacity is small and the number of digits is small, the calculation speed becomes faster.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a flow rate measuring device implemented in the present invention, FIG. 2 is a diagram showing a control circuit implemented in the present invention, and FIGS. 3A and 3B illustrate an example of an embodiment of the present invention. Diagram showing the flowchart, Figure 4 A,
B is a diagram showing flowcharts of other examples. 2...Flowmeter, 4...Flow rate pulse transmitter, 5...
...Control device, 6...Specific gravity setting dial, 9...Flow rate display meter, 52...Central control unit, 54...Storage means, 55...Temporary storage means.

Claims (1)

[Claims] 1. A flow signal transmitter installed in the flowmeter, a temperature measuring device for measuring the temperature of the fluid, a specific gravity setting device for setting the specific gravity of the fluid, and a memory for storing the temperature correction coefficient of the fluid in correspondence with the temperature and specific gravity. and a control device for calculating a temperature-corrected flow rate value, and the temperature correction coefficient stored in the storage means is a temperature correction coefficient that is calculated based on a volume conversion coefficient corresponding to each specific gravity at a specific interval at a predetermined temperature. The difference in volume conversion coefficients for each specific interval is multiplied by 10,000, and the control device is based on the temperature correction coefficient stored based on the temperature measured by the temperature measuring device and the specific gravity set by the specific gravity setting device, The volume conversion coefficient of the set specific gravity at the measurement temperature is calculated using the formula [(Volume conversion coefficient of reference temperature)
−{sum of temperature correction coefficients between measured temperatures)/
(10000)}], and if the measured temperature and set specific gravity are intermediate values between the stored temperature and specific gravity, it is calculated by proportional distribution based on the above calculation formula, and the flow rate signal generator 1. A temperature-corrected flow rate measuring device, characterized in that it calculates a temperature-corrected flow rate value using a flow rate signal and a calculated volume conversion coefficient.