Manufacturers sell CH-L type elbow flow meters Steam flow meters Gas elbow flow meters at affordable prices

product details

product details

1、 Overview

As a young and ancient measuring product, the elbow flowmeter has been recognized for its advantages in the measurement industry and is gradually being widely used in various fields such as industry and public utilities. The advantages of elbow flow meters are mainly reflected in their reliable principle, simple structure, energy conservation and consumption reduction, and low maintenance. The primary sensing element of elbow flow meters, elbow sensors, is suitable for harsh industrial environments and has good applicability to various harsh on-site conditions such as high temperature, high pressure, humidity, dust, vibration, etc Ф 20- Ф Accurate flow measurement is performed on pipelines with a diameter of 2000mm or even larger (through variable diameter rectifiers). With the cooperation of specialized intelligent instruments or conversion modules, it can meet various measurement and output needs of different industries such as electricity, heating, metallurgy, chemical industry, urban water supply and heating, building air conditioning, etc. Its application and development prospects are broad.

2、 The working principle of the bend sensor

A fluid flows through a pipeline at a certain temperature and pressure, and when it flows through an elbow, the fluid will undergo corresponding circular rotational motion. According to theories such as fluid forced swirling, the circular motion of a fluid in a pipeline is similar to that of a solid in a spatial state. Therefore, the fluid will inevitably generate inertial centrifugal force, which is related to factors such as the flow velocity of the fluid, the density of the fluid, and the curvature radius of the curved pipe sensor that performs the circular motion.

Due to the known curvature radius of the bend sensor, the density of the fluid flowing through the bend sensor can be accurately calculated using the host computer by measuring the temperature, pressure, and other parameters of the fluid. Therefore, the magnitude of the centrifugal force generated on the bend sensor is only a function of the fluid flow rate. As long as the magnitude of centrifugal force is measured (indirectly through a differential pressure transmitter), the flow rate of the fluid in the pipeline can be measured. The flow rate can be calculated and determined by multiplying it by the cross-sectional area of the pipeline and the density of the fluid.

3、 Classification of Bend Sensors

The primary sensing element of the elbow flowmeter is divided into three types based on the installation of the elbow sensor on the pipeline:

The 90 ° bend sensor is used at the 90 ° bend connection of the process pipeline to replace the original bend

180 ° bend sensor is used on straight pipe lines to replace some straight pipe sections

The 135 ° bend sensor is used at the 135 ° bend connection of the process pipeline to replace the original bend

The two small straight pipes welded on different bend sensors are called pressure takers, and the positive pressure measurement is conducted in one direction with a larger bend arc length, as shown in Figure 1 (taking the horizontal bend structure diagram as an example):

Figure 1

Schematic diagram of different bent pipe sensors

The 90 ° and 135 ° bend sensors are subdivided into three types based on the plane formed by the installation process pipeline turning:

The positive pressure measurement is carried out by installing a bend sensor vertically on the upper surface, and the plane formed by the turn is a vertical plane, and the longer side of the bend arc of the turn is on top.

The negative pressure sensor is installed vertically on the top, and the plane formed by the turning of the bend sensor is a vertical plane, and the longer side of the turning bend arc is below

The plane formed by the turning of the horizontally installed bend sensor is a horizontal plane
The 180 ° bend sensor only has a horizontal installation form, and other installation forms are meaningless.

See Figure 2 for details (180 ° horizontal installation diagram omitted)

Figure 2 Vertical Installation Diagram

4、 Installation dimensions of bend sensor

For 90 ° and 135 ° bends, as long as the originally connected elbow uses a standard elbow with a bend to diameter ratio of 1.5, the 90 ° and 135 ° bend sensors can be well replaced, and their installation dimensions are slightly smaller. For the 180 ° bend sensor, it is necessary to replace some straight pipe lines, and its installation dimensions are shown in Table 1 below:

Table 1 Installation Dimensions of 180 ° Bend Sensor

Explanation: Installation dimension L is due to the outer diameter dimension φ If there is an error due to deviation from the engineering size, the actual size of the product should prevail.

5、 Basic characteristics of elbow flow meters

Characteristics of Bend Sensors

No additional resistance loss (for 90 ° and 135 ° bend sensors), saving power consumption for fluid transportation, and reducing operating costs

Easy to install, leak free, maintenance free, wear-resistant, and can be directly welded and installed on pipelines

High temperature resistance, corrosion resistance, vibration resistance, impact resistance, and good magnetic resistance

Strong adaptability, wide range, and low requirements for straight pipe sections

High measurement accuracy and good reproducibility; The measurement accuracy can reach over ± 1%, and the reproducibility can reach as high as 0.2

Long service life

Characteristics of TKWG series hosts

Multi circuit and multi parameter display

Advanced touch buttons with novel appearance and structural design for easy operation

Power failure protection function to protect important data from loss after power failure

The complete real-time operation compensation and digital filtering functions have improved the measurement accuracy and stability of the system.

Intelligent logic judgment and self diagnosis function

RS-232 (or 485) serial interface output, which can directly communicate with other instruments or computer systems for networking, meeting real-time communication between users and external devices, or external control and printing functions.

Standard (4-20mA) analog output (can be selected according to user needs)

Heat accumulation function, which can be used to measure the cumulative heat of water vapor and heating hot water

Clock function, unaffected by host power supply, can provide accurate time for users

Small size, low power consumption, stable operation, and high measurement accuracy

6、 Basic structure of TKWG series host

The TKWG series elbow flowmeter host mainly consists of a chassis, front panel, rear panel, LCD display module, and switch power supply.

Front panel

As shown in Figure 3, the front panel mainly consists of a display screen and buttons. The display screen is an eight digit code segment LCD display screen. There are four working parameter markers on the left and right sides of the display screen. When the symbol in the LCD screen lights up, the parameter value displayed in the display screen is the corresponding quantity of the indicated unit at this moment. From top to bottom on the left are real-time clock (T), cumulative time (∑ T), cumulative flow (t), and cumulative heat (GJ); From top to bottom on the right are temperature, pressure (MPa), instantaneous flow rate (t/h), and instantaneous heat (GJ/h). The display format of real-time time is: XX: DD: HH: MM (month: day: hour: minute); The cumulative time display format is: XX.DD.HH.MM, indicating a total of XX months, DD days, HH hours, and MM minutes of operation.

Rear panel:

There is a wiring board with a pair of terminals on the rear panel, and the ZWRY host measures two flow channels. The first connection is to the AC220V AC power supply, with the top connected to the zero line of the power supply and the bottom connected to the live line of the power supply; The second pair of terminals is the grounding terminal, and the upper end is marked with GND terminal as the grounding point, which should be well grounded; The third pair of terminals is labeled as TXD, and RXD is the RS232 bus output terminal; The fourth pair of wiring terminals are labeled as analog output, representing the standard signal output terminal of the host 420mADC, and their positive and negative signs indicate the positive and negative poles of the output; The last six pairs are signal input terminals, respectively connected to differential pressure transmitter 2（ Δ P 2), pressure transmitter 2 (P2), temperature transmitter 2 (T2); Differential pressure transmitter 1（ Δ P 1), Pressure transmitter 1 (P1), Temperature transmitter 1 (T1), marked with (-) to indicate the negative terminal of the transmitter, and marked with (+) to indicate the positive terminal of the transmitter; As shown in Figure 3

Figure 3 Schematic diagram of the rear panel

Mainboard

The motherboard is the center of the entire system, which mainly uses the PIC16F8xx microcontroller with the strongest functions of the PIC series as the core component, supplemented by external clock RAM chips DS1302, MAX232 (485) and other serial ports for signal input, 4-20mA analog signal output circuit AD420, code segment liquid crystal display module, etc. It is a microcomputer system with strong functions such as calculation, logic analysis, storage, display, communication, etc.

Switching power supply

This power supply is the power supply for the entire system, with an input of 220V, AC, and an output of two DC voltages.

+5V. DC: Used for motherboard voltage

+24V. DC: For external transmitter use

7、 Host parameter settings

Enter key is the confirmation key for parameter setting;

>>The key is a shift key;

The key is the addition of one key;

Parameter setting steps:

Press the enter key to enter the parameter setting state. At this point, the host display screen will display the input password parameter status and its corresponding flag code; Press the shift key ">>" and add a key ">" to enter the password, which is already set by the manufacturer at the factory. If the password is entered correctly, you can modify the parameters. Otherwise, you can only view the parameters and cannot modify them.

When entering the parameter modification state, for parameters that are not modified, you can directly press the confirmation key "enter" to pass. At this time, the display screen will display the next parameter and parameter flag code in sequence, as shown in Table 2;

For parameters that need to be modified, the following operations can be performed: repeatedly pressing the shift key ">>" can move the flashing digit (only the digit with the cursor flashing can be modified). When the digit that needs to be modified flashes, you can press the ">" button to perform the "add one" operation. After adjusting the digit correctly, press the shift key ">" to shift the flashing digit and make the next digit modification; After all the parameters have been modified, press the shift key ">>" to move the cursor to a non flashing position. Press the confirmation key "enter" to confirm and enter the next parameter setting state. Otherwise, if the confirmation key "enter" is pressed when there are still flashing digits, the modification of this parameter will be invalid, and the system will directly enter the next parameter setting state without making any modifications to the parameter.

After all parameters are set, the host automatically returns to the normal operating state displaying the measured values.

Clear Accumulated Quantity: Press the "enter" button to display "1CXXXXX" on the display screen; At this point, the first X digit will flash. If the flashing data is not the first digit, press the shift key ">>" to move the flashing cursor to the first digit; Press the plus key ">" to set the first flashing "X" to "1", then press the shift key ">>" to move the cursor to a non flashing position. Press the confirmation key "enter" to confirm and the accumulated quantity is cleared.

Set the space installation status of the elbow sensor:

Refer to the above steps to enter the parameter setting state of the host;

Press the "enter" key continuously to make the display screen display "1C ×××××”；

Press the shift key ">>" to move the flashing cursor to the second position“ ×” Department;

Press the ">" button to make the second digit flash“ ×” Set to "0, 1, or 2 or 3"; (The specific meanings of 0, 1, 2, and 3 are shown in Table 3)

When pressing the shift key ">>" to move the cursor to a non flashing position, press the confirmation key "enter" to confirm;

Table 2: Parameter Code Table

8、 Display functions and operations under normal working conditions

Enter key is the parameter setting check key;

>>The key is an automatic cycle display key;

The key is a fixed point display key;

1. Multi parameter cyclic display:

Press the cycle button ">>" and the host will enter the cycle display mode. The order of the cycle display is: medium temperature, medium pressure, instantaneous flow rate, instantaneous heat, real-time time, accumulated time, accumulated flow rate, accumulated heat, medium temperature. The display time for each parameter during cyclic display is five seconds. For air, gas, etc., there is no heat display as needed.

2. Fixed point display:

When the host is in a cyclic display state, in order to better observe a certain parameter, you can press the fixed point display key ">" once the parameter is displayed on the display screen, and the host will change from cyclic display to fixed point display. If no other operations are carried out, the host will always maintain the fixed point display mode. This design will be beneficial for the long-term detection of instantaneous flow when the meter is used as a process flow meter. To restore the cyclic display mode in fixed point display mode, simply press the cyclic key ">>" again.

3. Check the setting parameter values:

The so-called checking and setting parameter values is to cycle through the preset values of each parameter on the display screen, and after one cycle, the host automatically returns to the normal operating state of displaying the measured values.

The specific operation explanation is as follows: press the parameter setting check button enter, and the host will enter the password parameter input state. Press the enter button to skip the password and enter the parameter view state. At this point, the first two digits of the display screen will display the identifier of the parameter, and the last five digits will be the set value of the parameter. The order of their sequential display is shown in Table 1. Then, continue to press the enter key to display the next parameter. After all the parameter settings are displayed in order, the host returns to the normal operating state where the measured values are displayed.

9、 Main technical indicators of TKWG series host

Measurement range:

Pipe diameter: Φ twenty Φ 2000mm;

Flow rate: 0.212.0m/s (liquid medium);

7120 meters/second (steam or other gases);

Temperature: 0500;

Pressure: 05.5MPa;

Precision:

Temperature measurement error: 0.2;

Pressure measurement error: 0.2;

Instantaneous heat measurement error: less than 2.0% F.S;

Instantaneous flow measurement error: less than 1.5% F.S.

Host power consumption:

Less than 25W when the working power supply is 220V;

Host working environment requirements:

Temperature: -1045;

Humidity: less than 85%;

Display method:

LCD display, capable of displaying real-time clock (T), cumulative time (∑ T), cumulative flow (Kt), and cumulative heat (GJ); From top to bottom on the right are temperature, pressure (MPa), instantaneous flow rate (t/h), and instantaneous heat (GJ/h). It can also be displayed according to specific requirements.

6. Output mode (selected during ordering, if not specified, the instrument does not have output function):

A) RS-232 or RS-485 serial interface output;

B) 420mA standard signal output.

7. Alarm function (selected when ordering, if not specified, the instrument does not have alarm function):

The host can provide high and low limit alarms for the four measured parameters of flow, temperature, pressure, and differential pressure, and has a pair of output contacts for outdoor sound and light alarm.

8. Overall dimensions: 160 × eighty × 200 (mm);
Composition of TKWG series measurement system

The basic components of a bent pipe flowmeter include a bent pipe sensor and host, as well as a differential pressure transmitter (which must be configured), a pressure transmitter, a temperature transmitter (which can be selected according to the requirements of the tested object), and other accessories. (Refer to the attached figure)

The differential pressure transmitter is used to detect the differential pressure value generated by the elbow sensor, so it is an indispensable accessory for the elbow flowmeter measurement system

Whether the system is equipped with pressure and temperature transmitters depends on the specific measurement object. For systems measuring steam or other gas media, when measuring the differential pressure of bent pipe sensors, it is necessary to simultaneously measure the temperature and pressure of the medium in order to provide necessary real-time temperature and pressure density compensation for steam or gas, in order to ensure the measurement accuracy of the system. Therefore, in principle, temperature and pressure transmitters must be configured; When measuring liquid media, as long as the temperature and pressure of the medium are not high or low, the fluctuation range is not large, and the density change of the liquid is not significant, the system can not be equipped with temperature and pressure transmitters and corresponding devices.

Other components of the system

Three valve manifold used in conjunction with differential pressure transmitter

Additional disc condensers for measuring steam or other high-temperature condensable gases

Needle valve and plug valve matched on the elbow sensor

Installation platform and temperature sensor with protective sleeve for temperature transmitter (Pt100)

Stop valve for pressure measurement port and drain valve for differential pressure transmitter

Other installation materials: pressure conduit（ φ fourteen × 2 seamless steel pipes and signal wires (about 0.5 double core shielded wire), etc. (provided by the user)

11、 Installation of the system

For the installation of pressure, differential pressure, temperature transmitters, and temperature sensors, in principle, as long as they comply with conventional installation specifications, they can meet the requirements of this system. The specific installation requirements can be found in the installation manual for pressure, differential pressure, temperature transmitters, and temperature sensors, which will not be detailed here.

Installation requirements for bend sensor

The elbow sensor is installed using welding method at the 90 degree bend of the measuring pipeline, and its spatial installation status can be arbitrary in principle. That is to say, there are no strict requirements for orientation or direction when installing the elbow sensor. Overall, there are four installation states to choose from:

Horizontal to horizontal;

Vertical installation of positive pressure measurement on top;

Install the positive pressure measurement vertically downwards;

Any spatial state.

In principle, all four states mentioned above can be used when installing bent pipe sensors. However, for some measured media, selecting an appropriate installation state can greatly simplify installation and debugging work, and also greatly benefit the improvement of system measurement accuracy. Therefore, it is very important to correctly select the installation status of the elbow sensor. Specifically manifested as the following principles and methods:

For elbow sensors that measure general liquid media, they can be installed in any state because the liquid in the pipe and the liquid in the pressure pipe are almost under the same working conditions. Regardless of the relative position of the two pressure ports of the elbow sensor (referring to the up and down relationship), there is no need to migrate or compensate for the differential pressure transmitter, Therefore, the installation orientation of the bend sensor is independent of the measurement accuracy of the system.

For systems that measure hot or cold water (referring to the significant difference between the liquid temperature in the pipeline and the ambient temperature), if the elbow sensor is not installed in a horizontal to horizontal state, there will inevitably be a height difference H value between the two pressure ports of the elbow sensor. Due to the different temperature conditions of the liquid in the main pipeline and the liquid in the pressure pipe, there is a certain difference in its density, in order to improve the measurement accuracy of the system, The deviation value of the differential pressure transmitter caused by this height difference and temperature difference must be migrated and compensated. The migration amount can be calculated using the following equation:

Δ P=H（ ρ 1- ρ 2) G

Among them:

Δ P - - migration amount of differential pressure transmitter;

H - the height difference between two pressure taps;

ρ 1- - Liquid density inside the pressure pipe;

ρ 2- Liquid density inside the pipeline;

G - Gravitational acceleration

The specific choice of positive or negative migration depends on the direction of pipeline installation and whether the pipeline is filled with hot or cold water. The elbow flowmeter adopts computer automatic migration compensation technology, which calculates the fluid density difference between the pressure pipe and the main pipeline in real time based on the fixed height difference H value and the measured temperature value, and directly eliminates the differential pressure error from the differential pressure transmitter measurement differential pressure value.

The installation of bent pipe sensors for measuring steam or other condensable gases is mainly focused on the fact that these media will condense into liquid at room temperature, resulting in the accumulation of liquid in the pressure pipe. Therefore, when the elbow sensor is not installed in a horizontal to horizontal state, it is necessary to compensate for the migration of the liquid column height difference in the pressure pipe caused by the height difference between the two pressure ports. The accuracy of this migration compensation is one of the most important conditions to ensure the accuracy of the measurement system. Due to the low density of the media in the process pipeline (as they are in the vapor or gas state) and the high density of the media in the pressure pipe (as they are in the liquid state), the density difference between these two media is significant. Therefore, the migration amount of the differential pressure transmitter is relatively large, and the bend sensor is a low differential pressure sensor that can generate relatively small differential pressure values within the normal working range, So it is very important to ensure the migration accuracy of the differential pressure transmitter.

In order to avoid additional measurement errors caused by improper migration as much as possible, it is recommended to take the following technical measures when measuring these media. Install a disc condenser at the pressure inlet of the elbow sensor to ensure the stability of the condensate liquid level in the pressure pipe;

As long as the on-site conditions permit, the installation of the elbow sensor and sensor adopts a horizontal to horizontal installation method, so that the two pressure ports of the elbow sensor are on the same horizontal plane, fundamentally eliminating the trouble of compensating for the migration of the differential pressure transmitter;

Due to the fact that the two pressure ports of the bend sensor are located on both sides of the bend, it is not easy to accurately ensure that the two disc condensers and pressure ports are on the same horizontal plane. We provide a simple measurement method for users to refer to during installation (as shown in Figure 5). Take a sufficiently long transparent plastic tube and fill it with water. Place both ends of the plastic tube at the two pressure measuring ports on both sides of the bend. Carefully adjust the height of the disc condenser using the visible horizontal liquid level inside the tube at both ends of the plastic tube, which can easily make the two disc condensers on the same level.

No matter which installation method is used, one thing that needs to be followed together is that before the system officially runs, the air in the pressure pipe and transmitter must be completely discharged to ensure the correct operation of the system. Therefore, for some systems measuring liquids, an air collection tank needs to be installed at the highest point of the pressure pipe to capture trace gases that may enter the pressure pipe during operation. For the same reason, during equipment installation, it is necessary to ensure a tilt of around 10:1 for the horizontal pressure pipe, and the tilt direction should be in favor of gas returning to the main pipeline or entering the gas collection tank.

Requirements for straight pipe sections before and after bending sensor

The requirement for the straight pipe section in front of the bend sensor is 5D, and the requirement for the straight pipe section in the back is 2D. If the front of the sensor is a weak interference source, its straight pipe section can also be correspondingly reduced.

Installation of the host

The host can be installed on various dashboard or instrument box panels, and it is important to ensure good grounding of the instruments. At the same time, the installation of the host should also be as far away from environments with strong electrical and magnetic interference as possible, especially in the front direction of the host where there should be no sources of strong electrical and magnetic interference.

12、 System debugging and operation

According to the requirements of system configuration, check whether all equipment, pipelines, valves, connectors, wires, wiring terminals, plugs, etc. are installed completely, correctly, and firmly, and whether the pipelines and equipment are not blocked or leaking, and whether the wires are not misconnected, short circuited, or disconnected. System debugging work can only be carried out after confirming that there are no errors.

Power on the host. While the host is powered on, the host also supplies power to each transmitter. At this time, the host should display the corresponding values of each transmitter. Due to transportation and other reasons, the transmitter can be initially zeroed at this time.

The operation of temperature and pressure transmitters is very simple, basically by connecting the wires and opening the pressure measuring valve, they can operate normally. However, one thing to note about pressure transmitters is that when the elbow flowmeter is used to measure steam or other condensable gases, if the vertical distance between the installation position of the pressure transmitter and the pressure tap is large, the liquid column in the pressure pipe (usually located below the pressure tap) will cause the pressure transmitter to indicate a high value. Therefore, it is necessary to make appropriate corrections to the zero position of the pressure transmitter to ensure the accuracy of the pressure measurement value.

The operation of the differential pressure transmitter can be carried out as follows (taking the measurement of steam medium as an example):

Close the positive and negative pressure valves of the three valve assembly tightly, open the balance valve, and then adjust the zero position of the differential pressure transmitter;

Open the primary valve behind the disc condenser on the elbow sensor, then open the two drain valves on both sides, and thoroughly blow out the pressure pipe with steam. The purpose is to clean the pressure pipe, and to completely exhaust the air inside the pressure pipe until it is deemed satisfactory. (Note: At this time, the positive and negative valves of the three valve assembly must be closed tightly.)

At this point, close the drain valve tightly and allow the steam to naturally condense in the pressure pipe until the entire pipeline and disc condenser are fully filled with condensed water. When there is sufficient condensate in the pressure pipe, the positive and negative pressure valves of the three valve assembly can be opened, and the balance valve can be closed to allow the condensate to enter the positive and negative pressure chambers of the differential pressure transmitter separately. To ensure that all residual air in the positive and negative pressure chambers of the differential pressure transmitter can be completely discharged, the exhaust valve of the positive and negative pressure chambers can be appropriately opened for exhaust, but steam must not be allowed to enter the positive and negative pressure chambers of the differential pressure transmitter.

Due to the accumulation of condensate water taking a certain amount of time, the indication of the differential pressure transmitter may not be accurate at the beginning. After the condensate water completely fills the entire measurement system (including the pressure pipe, the positive and negative pressure chamber of the differential pressure transmitter, and the disc condenser), the indication of the differential pressure transmitter will tend to normal.

After all transmitters are put into operation normally, the official operation of the host can be carried out. The steps are as follows:

First, check, set or modify the values of various relevant parameters. (such as the diameter, differential pressure, temperature, pressure, etc. of the bent pipe sensor), and confirm that they are consistent with the actual situation on site;

Enable the host to enter a normal operating state, at which point the host begins to perform normal calculations;
At this point, the system has entered a normal operating state.