JPH08136305A - Transmitter - Google Patents

Abstract

PURPOSE: To compensate pressure and temperature as well as the differential pressure and pressure of a fluid circulating in a plant pipe using one transmitter. CONSTITUTION: In a transmitter for measuring the differential pressure/pressure of a process fluid circulating in a process pipe and for converting them to flow-rate signals and then transmitting them to an upper equipment, a differential signal conversion part 61 for measuring the differential pressure of fluid obtained from differential pressure take-out ports across a fluid differential pressure generator in the plant pipe, a pressure signal conversion part 62 for measuring the pressure of the fluid in the plant pipe, a compensation processing part 63 for compensating pressure and temperature using temperature signals from the output of the signal conversion part and a temperature sensor, and a square-root operation means 64 for converting the compensated signal to a flow-rate signal are included in one transmitter body 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved transmitter for measuring a differential pressure of a process fluid or a pressure.

[0002]

2. Description of the Related Art Generally, the pressure of a process fluid such as gas or liquid flowing in a process pipe is closely related to the flow rate because it is determined by the position and energy of the fluid. Therefore, the flow rate of the fluid can be measured by measuring the pressure of the fluid. Therefore, most of the flow rate detection ends are composed of pressure detection elements, and improvement of pressure measurement accuracy or pressure measurement technology is important for plant instrumentation.

By the way, conventionally, when measuring the differential pressure / pressure of the process fluid flowing through the process pipe, a differential pressure transmitter and a pressure transmitter are separately installed on the process pipe, and these transmitters respectively measure. The flow rate signal of the process fluid is obtained from the generated signal and then transmitted to the controller.

Further, in these differential pressure transmitters and pressure transmitters, temperature correction and pressure correction are carried out because measurement errors occur due to static pressure of the pressure-receiving body holding the diaphragm, deformation due to temperature, and other factors. However, these correction processes are performed exclusively by software.

[0005]

Therefore, in the above-described differential pressure / pressure measurement, it is necessary to install two transmitters for differential pressure measurement and pressure measurement, and accordingly, two transmitters are required. Cost and installation space are required. Considering the large number of installations of this type of transmitter at various places in the plant and the number of installation steps, enormous equipment cost is required and the installation work of the transmitter becomes complicated. is there.

Further, for temperature and pressure correction, programs for temperature correction and pressure correction must be individually incorporated. The present invention has been made in view of the above circumstances, by measuring the differential pressure and pressure of the fluid in one, and,
It is an object to provide a transmitter that performs pressure correction, temperature correction, and the like.

[0007]

In order to solve the above-mentioned problems, the invention corresponding to claim 1 is a transmitter for measuring a differential pressure / pressure of a process fluid flowing through a process pipe and transmitting it to a host device. A differential pressure signal converter for measuring the differential pressure of the fluid taken in from the differential pressure outlets before and after the fluid differential pressure generator provided in the process pipe, and a pressure signal for measuring the pressure of the fluid in the process pipe. One transmitter main body, which is a pressure receiving unit, includes a conversion unit and a correction processing unit that corrects pressure and temperature using outputs of these signal conversion units and a temperature signal from a temperature sensor installed in the process pipe. It is a transmitter that is built into the hardware.

Next, the invention according to claim 2 measures the differential pressure / pressure of the process fluid flowing through the process pipe,
In a transmitter for converting into a flow rate signal and transmitting it to a higher-level device, a differential pressure signal conversion unit for measuring the differential pressure of the fluids respectively taken in from the differential pressure outlets before and after the fluid differential pressure generator provided in the process pipe. A pressure signal conversion unit that measures the pressure of the fluid in the process pipe, and a correction process that corrects the pressure and temperature using the output of these signal conversion units and the temperature signal from the temperature sensor installed in the process pipe. A transmitter and a square root calculation processing unit for converting the signal corrected by the correction processing unit into a flow rate signal in one transmitter main body which is a pressure receiving unit in terms of hardware.

[0009]

Therefore, according to the invention corresponding to claim 1, by taking the above-mentioned means, the fluids respectively taken in from the differential pressure outlets before and after the fluid differential pressure generator provided in the process pipe are transmitted. Introduced into the differential pressure signal converter of the main unit to measure the differential pressure, similarly introduce the fluid in the process pipe into the pressure signal converter of the transmitter main unit to measure the pressure, and also install a temperature sensor in the process pipe. After being installed, the detection signal of the temperature sensor is converted into a temperature signal by a temperature signal converter and then introduced into the correction processing unit of the transmitter body. Here, since the correction processing unit of the transmitter main body captures the output and temperature signal of each signal conversion unit and corrects the pressure and temperature, it is possible to measure the differential pressure and the pressure using one transmitter main body. Besides, the pressure and temperature can be corrected, the installation work becomes easy, and the cost and the installation space are greatly reduced. In addition, a hardware temperature / pressure correction circuit can be compactly stored in the transmitter body.

Further, the invention according to claim 2 is the same as that of the invention according to claim 1 if a square root operation processing unit is provided in the transmitter body in addition to the components of the invention according to claim 1. In addition to the function, it can be converted into a flow rate signal and transmitted to a host device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a transmitter according to the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a transmitter, FIG. 2 is a functional configuration diagram of a transmitter main body which constitutes the transmitter,
FIG. 3 is a diagram for distinguishing the hardware and software ranges of the transmitter.

In this transmitter, a fluid pressure difference generator 2 having a function of resistance to fluid such as an orifice for generating a high / low pressure difference is attached inside the pipe at an appropriate position of the process pipe 1, and the fluid pressure difference generation is generated. Among the differential pressure outlets before and after the body 2, the high pressure side main valve 3 is provided at the upstream side differential pressure outlet, and the low pressure side main valve 4 is provided at the downstream side differential pressure outlet.

On the output side of the high-pressure side main valve 3 and the low-pressure side main valve 4, a transmitter main body 6 having a pressure receiving main body is attached via a manifold valve 5, and a differential pressure outlet before and after the fluid resistance generator 2 is attached. The differential pressure of the fluid is detected.

Further, a pressure outlet is provided at a position which is not affected by the fluid flow at the differential pressure outlet, for example, at a position of the appropriate process pipe 1 upstream from the differential pressure outlet, and the pressure outlet is provided. The pressure guiding pipe 7 is guided to be connected to the transmitter body 6, and the pressure of the fluid in the process pipe 1 is taken in. Reference numeral 8 is a main valve on the side for taking in the fluid pressure.

Further, a temperature sensor 9 for measuring the temperature of the fluid in the process pipe 1 is provided upstream of, for example, the pressure outlet of the process pipe 1, and a temperature signal for converting a detection signal from the temperature sensor 9 into a temperature signal. A converter 10 is provided, and the temperature signal subjected to signal conversion here is introduced into the transmitter main body 6 to perform temperature correction processing of the differential pressure.

Therefore, as shown in FIG. 2, the transmitter main body 6 is displaced by a differential pressure detecting diaphragm known in the prior art which is displaced by a differential pressure between a high pressure and a low pressure of a fluid flowing in the process pipe 1 and the displacement of this diaphragm. The differential pressure signal conversion unit 61 having a capacitance type / semiconductor type differential pressure detection unit for detecting the differential pressure from the pressure detection diaphragm, the pressure detection diaphragm displaced by the pressure of the fluid passing through the pressure guiding tube 7, and the pressure detection. A pressure signal conversion unit 62 having a pressure detection unit of the same capacitance type, a semiconductor type, or the like, which detects pressure from the displacement of the diaphragm for use, and the differential pressure signal conversion unit 61, the pressure signal conversion unit 62, and the temperature signal converter 10. A correction processing unit 63 for performing pressure correction and temperature correction using a signal from the sensor, and a square root calculation processing unit 6 for square root calculation of the signal after the correction processing to extract a flow rate signal Door is provided.

Next, FIG. 3 shows a relationship between a transmitter having a hardware configuration and a controller 20 which is a host device having a software configuration for executing a predetermined arithmetic processing based on a signal transmitted from the transmitter. FIG.

The controller 20 performs α correction on the flow rate signal transmitted from the transmitter main body 6 based on pressure loss due to the fluid pressure difference generator 2 or the like.
1 and a target value setting unit 2 for variably setting an appropriate target value SV
2 and PI based on the deviation between the process input value (for example, the flow rate signal) PV after α correction by the α correction means 21 and the target value SV set in the target value setting unit 22.
(P: Proportional, I: Integral) or PID (D: Derivative) adjusting operation is performed to obtain the operation output MV.

Reference numeral 24 is an operation end for controlling the flow rate in the plant piping based on the operation output MV from the adjusting means 23. Next, the operation of the apparatus configured as described above will be described.

At the time of measuring the differential pressure / pressure, for example, an open control signal is sent from the controller 20 or the like which is a higher-level device, and it is necessary to select one of the plural valves constituting each of the main valves 3, 4, 8 and the manifold valve 5. Then, the differential pressure detection fluid and the pressure detection fluid are individually taken from the process pipe 1 and introduced into the transmitter body 6.

Since the transmitter main body 6 is provided with a differential pressure detecting diaphragm and a differential pressure detecting section, and a pressure detecting diaphragm and a pressure detecting section, respectively, the differential pressure detecting section detects a differential pressure signal of the fluid. A is detected and sent to the correction processing unit 63, and the pressure signal B of the fluid is detected by the pressure detection unit and similarly sent to the correction processing unit 63.

Further, the temperature of the fluid in the process pipe is
It is detected by the temperature sensor 9, converted into a temperature signal C by the temperature signal converter 10, and sent to the correction processing unit 63 of the transmitter body 6. Here, the correction processing unit 63 receives the input signals A to C.
Using, for example, the calculation of (A · B) / C is performed to correct the pressure and temperature, and then the corrected signal D
The square root calculation processing unit 64 executes square root calculation processing for
A signal F proportional to the flow rate of the fluid flowing through the plant pipe 1 is taken out and transmitted to the controller 20 of the host device.

Therefore, according to the configuration of the above embodiment, the differential pressure detecting function and the pressure detecting function are internally provided in the transmitter main body 6, so that the differential pressure transmitter is provided on the process pipe as in the conventional case. Since it is not necessary to separately install the pressure transmitter and the pressure transmitter, the cost can be reduced, the installation work can be simplified, and the installation space can be significantly reduced.

Moreover, since the transmitter main body 6 is internally provided with the differential pressure detection function and the pressure detection function, the correction processing unit 63 can be provided inside the transmitter main body 6, and the pressure and temperature in the transmitter main body 6 can be provided. Can be corrected, which greatly contributes to downsizing of the entire transmitter.

Further, a differential pressure detecting function is provided in the transmitter body 6,
In addition to the pressure detection function and the correction processing function, if the square root calculation processing unit 64 is incorporated, a more compact structure can be obtained.
The flow rate of the fluid flowing through the plant piping can be measured from the measured values of the differential pressure and pressure.

[0026]

As described above, according to the present invention, it is possible to correct not only the differential pressure and pressure of the fluid flowing through the plant piping but also the pressure and temperature using one transmitter. The cost can be reduced, the installation work can be simplified, and the installation space can be significantly reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a transmitter according to the present invention.

FIG. 2 is a diagram showing a functional configuration of a transmitter main body which is a part of the transmitter.

FIG. 3 is a diagram showing a relationship between a transmitter having a hardware configuration and a controller having a software configuration.

[Explanation of symbols]

1 ... Plant piping, 2 ... Fluid differential pressure generator, 6 ... Transmitter main body, 9 ... Temperature sensor, 10 ... Temperature signal converter, 61 ... Differential pressure signal converter, 62 ... Pressure signal converter, 63 ... Correction processing Part, 64 ... Kaihei calculation processing part.

Claims (2)

[Claims] 1. A transmitter for measuring a differential pressure / pressure of a process fluid flowing through a process pipe and transmitting it to a host device, from a differential pressure outlet before and after a fluid differential pressure generator provided in the process pipe. From a differential pressure signal converter that measures the differential pressure of the fluid to be taken in, a pressure signal converter that measures the pressure of the fluid in the process pipe, and the output of these signal converters and a temperature sensor installed in the process pipe. And a correction processing unit that corrects pressure and temperature using the temperature signal of 1. in a transmitter main body that is a pressure receiving unit in terms of hardware. 2. A transmitter for measuring a differential pressure / pressure of a process fluid flowing through a process pipe, converting it into a flow rate signal, and transmitting it to a higher-level device. A differential pressure signal converter that measures the differential pressure of the fluids respectively taken in from the differential pressure outlets, a pressure signal converter that measures the pressure of the fluid in the process piping, and the outputs of these signal converters and the process piping. The pressure receiving unit includes a correction processing unit that corrects pressure and temperature using the temperature signal from the temperature sensor and a square root calculation processing unit that converts the signal corrected by the correction processing unit into a flow rate signal. A transmitter characterized by being built into one transmitter main body in terms of hardware.