JPS63218206A - Pressure detector - Google Patents

Abstract

PURPOSE:To precisely measure the pressure at the site where the temp. is changed, by immediately correcting the pressure value obtained by a pressure detector by calculation with the use of the temp. simultaneously detected by a temp. sensor provided at the measuring position. CONSTITUTION:A strain gage 3 for pressure detection is stuck on approximately the central part of the outer periphery of a pressure withstanding metallic material 1, and the strain quantity generated in the material 1 due to the variations in pressure is detected. Moreover, the temp. sensor 5 is stuck close to the stain gage 3. Those detection signals are sent to a computing and displaying device 6. At this part, the strain quantity obtained in an electric value is immediately calculated into a pressure value by the computer system, the pressure value is also calculated and corrected based on the temp. information, and the calculated pressure value is immediately displayed on a display part 6a or continuously recorded, if necessary.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to, for example, a pressure crystallizer that purifies or concentrates a specific component using pressure as the main control element and secondary influence of temperature. , relates to improvements in strain gauge type pressure detection devices applied to devices that are subject to temperature changes.

[Conventional technology]

As is well known, the pressure crystallization method is a relatively new purification and separation method in which only specific components are selectively crystallized and separated from a mixture of two or more types using pressure and temperature as control factors. Since this method purifies a specific component by crystallizing it using pressure as the main control element, detection and control of pressure are considered to be the most important management items. A strain gauge type pressure sensor disclosed in Japanese Patent Publication No. 61-58201 filed by the applicant of the present invention is currently in practical use as a pressure sensor for such applications. That is, this pressure detection device has a cylindrical pressure-resistant metal material 1 as a main body, for example, as shown in FIG. At the same time, the other end 1b is closed by the end M2, and the operating pressure is configured to act on the inside of the pressure-resistant metal material 1. Then, a strain gauge detection element (hereinafter simply referred to as a strain gauge) 3 is pasted on the outer circumferential surface of the pressure-resistant metal material 1, and the distortion of the pressure-resistant metal material 1 caused by the influence of high pressure accompanying the implementation of the pressure crystallization operation is is measured with a strain gauge, and this measured value is converted into pressure to determine the operating pressure. 4 in the figure indicates a sheath type heater, the function of which will be described later.

By the way, strain gauges, which are currently widely used, have an electrical resistor as an element, and there is a certain correlation between the pressure applied to the element and the amount of strain, and the relationship between the amount of strain and the electrical resistance. This type takes advantage of the fact that there is a certain relationship between the two phases, and detects changes in electrical resistance by amplifying them using a bridge circuit. Some devices are known that incorporate a circuit that compensates for the zero point output to perform temperature compensation, but the temperature compensation range is very close to room temperature, for example, about 0 to 40 degrees Celsius, as shown in Figure 3. It can only adapt to a limited range of temperature changes, and if there is a temperature change that exceeds the permissible range, it becomes impossible to adjust the zero point output, and the measurement accuracy decreases significantly. On the other hand, when carrying out the pressure crystallization method, for example, when solid-liquid separation is performed at a point (p+, T,) on the solid-liquid equilibrium line of impurity concentration x2 in FIG. Similarly, in the final stage of mother liquor separation (pressure release state), a slurry material with a high concentration of specific components may flow into the pressure sensor body through the pipe. In this state, when the operating pressure P acts on the next cycle of crystallization component 11 within the pressure detector body, the substance with a high specific component concentration crystallizes and solidifies, making subsequent pressure detection impossible. In order to avoid such problems, in the previously announced invention, as shown in FIG. 2, a Heshes type heater 4 is inserted into the pressure detector body 1 to prevent crystallization and solidification from proceeding by heating the inside. Rather, it is devised to melt the invading solid components.

The means for preventing such crystallization and solidification is not limited to heating with a sheath type heater as shown in FIG. 2, but indirect heating from the outside can also be employed.

[Problems to be Solved by the Invention] However, when the pressure sensor body is heated in the manner described above, the temperature increase due to the heating has a direct effect on the electrical resistance value detected by the strain gauge. The accuracy will be extremely reduced and the pressure control itself will fail.

The present invention has been made in view of these circumstances, and its purpose is to provide a device that can accurately detect pressure even when applied to areas where the temperature fluctuates significantly as described above. This is what we are trying to provide.

[Means for Solving the Problems] The configuration of the device of the present invention that has achieved the above object is a strain gauge type pressure sensing device used in places where temperature changes occur, and is a strain gauge type pressure sensing device that uses metal that deforms due to pressure. a pressure sensor whose detection element is a strain gauge affixed to the surface of the member; a temperature sensor affixed on the metal surface that is deformed by pressure in proximity to the strain gauge affixing position; and further the pressure sensor. The gist of the present invention is that it is provided with an arithmetic mechanism that corrects a pressure value including an error due to a temperature change obtained by using temperature information obtained by the temperature sensor.

[Operations and Examples] As described above, the pressure detection device according to the present invention includes (1) a pressure detector whose detection element is a strain gauge attached to the surface of a metal member that is deformed by pressure, and (2) at the strain gauge attachment position. It is characterized in that it is equipped with a temperature measurement sensor attached in close proximity, and (1) a calculation mechanism that corrects the pressure value obtained by the pressure detector using temperature information obtained by the temperature sensor, The pressure value determined by the pressure detector is immediately corrected using the temperature simultaneously detected by the temperature sensor installed at the measurement location, so even if the temperature of the measurement part suddenly changes, the pressure measurement value will not change. There is no risk of errors occurring, and pressure control can be performed accurately. For example, FIG. 1 is an explanatory longitudinal cross-sectional view showing an embodiment of the present invention, in which a cylindrical pressure-resistant metal material 1 is used as the metal member for measuring pressure that changes with pressure, as in the conventional example shown in FIG. , one end 1a thereof is connected to a conduit (not shown) communicating with the pressurizing chamber of the pressure crystallizer, and the other end 1b is closed by an end cover 2 which also serves as a holding part for the sheath type heater 4, Crystallization operation pressure is pressure resistant metal material i
It is designed to extend inward. A strain gauge 3 for pressure detection is attached to the outer circumferential surface of the pressure-resistant metal material 1 at approximately the center.
It is configured to be able to detect the amount of strain produced in the pressure-resistant metal material 1 due to changes in internal pressure, and a temperature sensor 5 is attached at a position close to where the strain gauge 3 is attached. These detection signals are then sent to the calculation/display device 6, where the computer system instantly calculates the amount of strain determined by the electrical resistance value into a pressure value, and corrects and calculates the pressure value using temperature information. The calculated pressure value is immediately displayed on the display section 6a, and is also continuously recorded if necessary. Incidentally, in displaying and recording these, it is of course possible to simultaneously display and record temperature changes accompanying repeated crystallization separation operations.

The strain gauge components used in the present invention do not require particularly special ones, and all conventional strain measurement elements such as linear resistors, foil resistors, and semiconductors can be used. In addition, all conventional types of temperature sensors such as adhesive thermocouples and resistance wire temperature gauges can be used. Also, pressure-resistant metal material 1
There is no reason to limit the shape and structure to what is shown in the diagram.
If the metal produces a certain strain in response to pressure, f
Although there are no particular limitations on the type, the most preferable one from the viewpoint of pressure resistance, stability of strain change depending on pressure, etc. is one having a cylindrical basic structure as shown in the drawing.

In any case, the present invention employs a configuration in which the actual pressure value is corrected and calculated using the temperature determined by the temperature sensor attached close to the attachment position of the strain gauge 3, so the response of the temperature measurement result is is extremely fast and can detect pressure with high precision without being adversely affected by temperature fluctuations.

It should be noted that the heating means when using the present invention for pressure measurement in a pressure crystallizer is not limited to heating with a sheath type heater as shown in the figure, but it is also possible to adopt an indirect heating method from the outside. The sheath type heater heating method is highly efficient as it can directly heat the area that requires heating, and has the advantage of minimizing the thermal effect on adjacent equipment, as well as the following applications: It becomes possible. That is, in carrying out the present invention, it is possible to configure the system so that the temperature measured by the temperature sensor 5 can be continuously recorded, as described above, but this is also shown in FIG. The temperature measurement result is transmitted to the output power source of the sheathed heater 4, and the internal temperature is adjusted to a preset target temperature (specifically, for example, the limit temperature at which crystallized material can be melted) according to the measured temperature. By incorporating a configuration that automatically controls the output of the power supply 7 so that Effective benefits can also be enjoyed from the meaning.

[Effects of the Invention] The present invention is configured as described above, and is capable of accurately measuring pressure using a strain gauge at a location where temperature changes occur, and provides a pressure crystallization method in which pressure is an important control element. This has led to the achievement of contributing to more accurate pressure control by accurately determining the influence of temperature when carrying out such operations.

[Brief explanation of the drawing]

Fig. 1 is an explanatory longitudinal cross-sectional diagram showing an embodiment of the present invention, Fig. 2 is an explanatory longitudinal cross-sectional diagram showing a conventional example, Fig. 3 is an explanatory diagram showing an example of zero point output compensation by temperature, and Fig. 4 is an explanatory diagram of a pressure crystal. 2 is a graph showing the relationship between pressure and temperature when carrying out an analysis method. 1...Metal member 2...End cover 3...Strain gauge 4...Sheath type heater 5...Temperature sensor 6...Calculation/display device 7...Output power supply

Claims (2)

[Claims] (1) A strain gauge type pressure detection device used in a place with temperature changes, which uses a strain gauge as a detection element attached to the surface of a metal member that deforms due to pressure;
The temperature sensor is attached to the metal surface that deforms due to pressure in the vicinity of the strain gauge attachment position, and the pressure value including an error due to temperature change obtained by the pressure sensor is measured by the temperature sensor. A pressure detection device characterized by comprising a calculation mechanism that performs correction using obtained temperature information. (2) The pressure detection device according to claim 1, wherein the metal member that is deformed by pressure is an internal pressure type cylinder with one end closed, and a sheath type heater is inserted inside. .