Liquid level measuring device with alternate positive pressure and negative pressure

Abstract

The utility model relates to the technical field of liquid level measurement based on differential pressure transmitters, in particular to a positive and negative pressure alternating liquid level measuring device which comprises a differential pressure transmitter, the positive pressure end of the differential pressure transmitter is connected to a measured device through a positive pressure air blowing pipe, and the negative pressure end of the differential pressure transmitter is connected to the measured device through a negative pressure air blowing pipe. The positive-pressure air blowing pipe extends into the position, below the liquid level of the tested equipment and close to the bottom of the tested equipment, of the tested equipment, the negative-pressure air blowing pipe is connected to a gas phase space on the top of the tested equipment, and a backflow prevention device is arranged between the positive-pressure air blowing pipe and the tested equipment. When the positive-pressure equipment is measured, gas is suddenly cut off from the positive-pressure gas blowing pipe, and the internal pressure of the positive-pressure equipment exceeds the pressure of the positive-pressure gas blowing pipe, a measured object enters the whole liquid level measuring system through the positive-pressure gas blowing pipe, so that pipeline blockage, instrument damage and the like are avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level measurement based on a differential pressure transmitter, in particular to a liquid level measuring device with alternating positive and negative pressures. Background Art

[0002] In the petrochemical industry or coal chemical industry, a large number of pressure vessels and reactors are used in the process flow to recover the heat generated by the process system. The control of the liquid level of the pressure vessel and reactor drum is very critical. If the liquid level is too high, the output steam may carry liquid and damage downstream equipment, such as the turbine; if the liquid level is too low, it may cause damage to the pressure vessel and reactor or even a safety accident. The same is true for the boiler drum level in the coal-fired power generation industry. Therefore, the drum liquid level must be accurately controlled to ensure that the fluctuation of the drum liquid level is within a reasonable range.

[0003] Although a variety of methods for controlling the drum liquid level have been developed and the required measurement effect has been achieved, in actual measurement, if the air blowing pipeline is suddenly cut off and the internal pressure of the positive pressure equipment exceeds the pressure of the air blowing pipeline, the object being measured will enter the entire liquid level measurement system through the positive pressure side sensor, causing pipeline blockage, instrument damage and other problems. In actual measurement, we have to consider how to avoid such problems. Therefore, a liquid level measurement device with alternating positive and negative pressures is needed. Utility Model Content

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the utility model is to provide a liquid level measuring device with alternating positive and negative pressures, which is used to solve the problem in the prior art of preventing the backflow of the measured object due to sudden gas interruption during measurement.

[0005] In order to achieve the above purpose and other related purposes, the utility model provides the following technical solutions:

[0006] A liquid level measuring device with alternating positive and negative pressures, comprising a differential pressure transmitter, wherein the positive pressure end of the differential pressure transmitter is connected to the device under test through a positive pressure air blowing pipe, and the negative pressure end of the differential pressure transmitter is connected to the device under test through a negative pressure air blowing pipe, wherein the positive pressure air blowing pipe extends into a position below the liquid level of the device under test and close to the bottom of the device under test, and the negative pressure air blowing pipe is connected to the gas phase space at the top of the device under test;

[0007] A backflow prevention device is provided between the positive pressure air blowing pipe and the equipment under test.

[0008] To implement the above technical solution, the gas enters the device under test through the positive pressure blowing pipe at the positive pressure end of the differential pressure transmitter. The positive pressure blowing pipe introduces the gas at the air inlet end into a position below the liquid level of the device under test, close to the bottom of the device under test. The negative pressure blowing pipe is connected to the gas phase space at the top of the device under test, and the liquid level of the device under test is measured using the differential pressure principle.

[0009] An anti-backflow device is added between the positive pressure air blowing pipe and the device under test to prevent the positive pressure air blowing pipe from suddenly cutting off the air when measuring the positive pressure device and the internal pressure of the positive pressure device from exceeding the pressure of the positive pressure air blowing pipe. This prevents the object under test from entering the entire liquid level measurement system through the positive pressure air blowing pipe, causing pipe blockage and instrument damage.

[0010] In one embodiment of the present invention, a gas filter and an air intake valve are provided on the air intake pipeline at the input end of the differential pressure transmitter.

[0011] To implement the above technical solution, a gas filter is provided to effectively filter the gas at the air inlet end to ensure the cleanliness of the gas, and the air inlet valve can control the switch of the air inlet end.

[0012] In one embodiment of the present invention, a positive pressure side valve is provided between the differential pressure transmitter and the backflow prevention device.

[0013] To implement the above technical solution, the setting of the positive pressure side valve can control the air flow switch of the positive pressure blowing pipe.

[0014] In one embodiment of the present invention, a negative pressure side valve is provided on the negative pressure blowing pipe.

[0015] To implement the above technical solution, the airflow switch of the negative pressure blowing pipe is independently controlled by the negative pressure side valve.

[0016] In one embodiment of the utility model, the positive-pressure air blowing pipe and the negative-pressure air blowing pipe are respectively provided with a positive-pressure dredging device and a negative-pressure dredging device connected to the outside.

[0017] By implementing the above technical solution and utilizing the positive pressure dredging device and the negative pressure dredging device, it is possible to facilitate the subsequent cleaning and dredging of the positive pressure air blowing pipe and the negative pressure air blowing pipe.

[0018] In one embodiment of the present invention, a positive pressure side sensor is provided between the backflow prevention device and the device under test.

[0019] The above technical solution is implemented to sense the airflow passing through the positive pressure end.

[0020] In one embodiment of the present invention, the differential pressure transmitter is connected to the positive pressure air blowing pipe and the negative pressure air blowing pipe through a constant current device.

[0021] The above technical solution is implemented to ensure the stability of gas transportation.

[0022] As described above, the utility model is a liquid level measuring device with alternating positive and negative pressures, which has the following beneficial effects: gas enters the device under test through the positive pressure air blowing pipe at the positive pressure end of the differential pressure transmitter, the positive pressure air blowing pipe introduces the gas at the air inlet end into a position below the liquid level of the device under test, close to the bottom of the device under test, the negative pressure air blowing pipe is connected to the gas phase space at the top of the device under test, and the liquid level of the device under test is measured by utilizing the differential pressure principle, and an anti-backflow device is added between the positive pressure air blowing pipe and the device under test to prevent the positive pressure air blowing pipe from suddenly running out of gas when measuring the positive pressure device and the internal pressure of the positive pressure device exceeds the pressure of the positive pressure air blowing pipe, so that the object under test will enter the entire liquid level measurement system through the positive pressure air blowing pipe, causing pipeline blockage, instrument damage, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown is a schematic structural diagram of a liquid level measuring device with alternating positive and negative pressures disclosed in an embodiment of the present utility model.

[0024] Component number description

[0025] 1. Differential pressure transmitter; 2. Positive pressure air blow pipe; 3. Negative pressure air blow pipe; 4. Equipment under test; 5. Anti-backflow device; 6. Gas filter; 7. Inlet valve; 8. Positive pressure side valve; 9. Negative pressure side valve; 10. Positive pressure dredging device; 11. Negative pressure dredging device; 12. Positive pressure side sensor; 13. Constant flow device; 14. Inlet pipeline. DETAILED DESCRIPTION

[0026] The following specific embodiments illustrate the implementation of the present invention, and those familiar with the technology can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0027] See also Figure 1 The utility model provides a liquid level measuring device with alternating positive and negative pressures, including a differential pressure transmitter 1, the positive pressure end of the differential pressure transmitter 1 is connected to a device under test 4 through a positive pressure air blowing pipe 2, the negative pressure end of the differential pressure transmitter 1 is connected to the device under test 4 through a negative pressure air blowing pipe 3, the positive pressure air blowing pipe 2 extends into a position below the liquid level of the device under test 4 close to the bottom of the device under test 4, the negative pressure air blowing pipe 3 is connected to the gas phase space at the top of the device under test 4, and a backflow prevention device 5 is provided between the positive pressure air blowing pipe 2 and the device under test 4.

[0028] The gas enters the device under test 4 through the positive pressure blowing pipe 2 at the positive pressure end of the differential pressure transmitter 1. The positive pressure blowing pipe 2 introduces the gas at the air inlet end into a position below the liquid level of the device under test 4, close to the bottom of the device under test 4. The negative pressure blowing pipe 3 is connected to the gas phase space at the top of the device under test 4, and the liquid level of the device under test 4 is measured using the differential pressure principle.

[0029] An anti-backflow device 5 is added between the positive pressure air blowing pipe 2 and the measured device 4 to prevent the measured object from entering the entire liquid level measurement system through the positive pressure air blowing pipe 2 when the positive pressure air blowing pipe 2 is suddenly cut off and the internal pressure of the positive pressure equipment exceeds the pressure of the positive pressure air blowing pipe 2 when measuring the positive pressure equipment, causing pipeline blockage, instrument damage, etc.

[0030] A gas filter 6 and an air intake valve 7 are provided on the air intake pipeline 14 at the input end of the differential pressure transmitter 1. The gas filter 6 is provided to effectively filter the gas at the air intake end to ensure the cleanliness of the gas. The air intake valve 7 can control the switch of the air intake end. A positive pressure side valve 8 is provided between the differential pressure transmitter 1 and the backflow prevention device 5. The setting of the positive pressure side valve 8 can control the airflow switch of the positive pressure blowing pipe 2.

[0031] A negative pressure side valve 9 is provided on the negative pressure blowing pipe 3, and the airflow switch of the negative pressure blowing pipe 3 is independently controlled by the negative pressure side valve 9. A positive pressure dredging device 10 and a negative pressure dredging device 11 connected to the outside are respectively provided on the positive pressure blowing pipe 2 and the negative pressure blowing pipe 3. The positive pressure dredging device 10 and the negative pressure dredging device 11 can be used to facilitate the subsequent cleaning and dredging of the positive pressure blowing pipe 2 and the negative pressure blowing pipe 3.

[0032] A positive pressure side sensor 12 is provided between the anti-backflow device 5 and the device under test 4 to sense the airflow passing through the positive pressure end. The differential pressure transmitter 1 is connected to the positive pressure blowing pipe 2 and the negative pressure blowing pipe 3 through the constant current device 13 to ensure the stability of gas delivery.

[0033] In the utility model, gas enters the device under test through the positive pressure blowing pipe at the positive pressure end of the differential pressure transmitter, the positive pressure blowing pipe introduces the gas at the air inlet end to a position below the liquid level of the device under test and close to the bottom of the device under test, the negative pressure blowing pipe is connected to the gas phase space at the top of the device under test, and the liquid level of the device under test is measured by utilizing the differential pressure principle. An anti-backflow device is added between the positive pressure blowing pipe and the device under test to prevent the positive pressure blowing pipe from suddenly cutting off the gas when measuring the positive pressure device and the internal pressure of the positive pressure device exceeds the pressure of the positive pressure blowing pipe, so that the object under test will enter the entire liquid level measurement system through the positive pressure blowing pipe, causing pipeline blockage, instrument damage, etc.

[0034] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. All equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A liquid level measuring device with alternating positive and negative pressures, comprising a differential pressure transmitter, wherein the positive pressure end of the differential pressure transmitter is connected to the device under test through a positive pressure blowing pipe, and the negative pressure end of the differential pressure transmitter is connected to the device under test through a negative pressure blowing pipe, characterized in that: The positive pressure air blowing pipe extends into a position below the liquid level of the device under test and close to the bottom of the device under test, and the negative pressure air blowing pipe is connected to the gas phase space at the top of the device under test; A backflow prevention device is provided between the positive pressure air blowing pipe and the equipment under test.

2. The liquid level measuring device with alternating positive and negative pressures according to claim 1, characterized in that: A gas filter and an air intake valve are arranged on the air intake pipeline at the input end of the differential pressure transmitter.

3. The liquid level measuring device with alternating positive and negative pressures according to claim 1, characterized in that: A positive pressure side valve is arranged between the differential pressure transmitter and the backflow prevention device.

4. The liquid level measuring device with alternating positive and negative pressures according to claim 1, characterized in that: The negative pressure blowing pipe is provided with a negative pressure side valve.

5. The liquid level measuring device with alternating positive and negative pressures according to claim 1, characterized in that: The positive-pressure air blowing pipe and the negative-pressure air blowing pipe are respectively provided with a positive-pressure dredging device and a negative-pressure dredging device which are connected with the outside world.

6. The liquid level measuring device with alternating positive and negative pressures according to claim 1, characterized in that: A positive pressure side sensor is provided between the backflow prevention device and the equipment under test.

7. The liquid level measuring device with alternating positive and negative pressures according to claim 1, characterized in that: The differential pressure transmitter is connected to the positive pressure air blowing pipe and the negative pressure air blowing pipe through a constant flow device.

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