Differential pressure type liquid level measuring equipment for fine chemical engineering

Abstract

The utility model discloses differential pressure type liquid level measuring equipment for fine chemical engineering, which comprises a differential pressure transmitter connected with a liquid container, the differential pressure transmitter comprises a positive pressure chamber, a negative pressure chamber, two pressure sensors positioned in the positive pressure chamber and the negative pressure chamber, and a central processing unit connected with the two pressure sensors, a positive pressure chamber of the differential pressure transmitter is communicated with the bottom end of the liquid container through a positive pressure guide pipe, and a negative pressure chamber of the differential pressure transmitter is communicated with an air part at the upper end of the liquid container through a negative pressure guide pipe; a temperature sensor is arranged at the lower part of the inner sidewall of the liquid container; an air pressure sensor is arranged on the inner side wall of the liquid container; the high-precision temperature sensor is arranged in the liquid container, the temperature change of the measurement environment is monitored in real time, temperature compensation is carried out on the measurement result through an algorithm according to the relation between the temperature and the medium density, and the influence of the temperature change on the liquid level measurement precision can be eliminated conveniently.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level measurement, in particular to a differential pressure type liquid level measurement device for fine chemical industry. Background Technique

[0002] The differential pressure type liquid level measurement device works based on the principle of hydrostatics. It determines the liquid level height by measuring the pressure difference generated by the liquid level height in the container. Usually, a pressure sensor is installed at the bottom of the container to measure the pressure at the bottom of the container, which includes the static pressure generated by the liquid level and the pressure of the upper gas in the container. At the same time, a pressure sensor is also installed in the gas phase space at the upper part of the container to measure the gas phase pressure. Subtracting the two pressures gives the pressure difference purely generated by the liquid level height. According to the relationship formula between the pressure difference and the liquid level height, the liquid level height can be accurately calculated.

[0003] For the current differential pressure type liquid level measurement device, the change in the temperature of the measured medium will affect the measurement accuracy. The temperature fluctuation will affect the density of the measured medium, thus affecting the calculation result of the pressure difference, and further reducing the accuracy of the liquid level measurement. Especially in the production of fine chemicals, the temperature change may be more frequent and intense, and this problem is more prominent.

[0004] For the current differential pressure type liquid level measurement device, if the pressure in the container is unstable, it will also interfere with the measurement result of the pressure sensor. For example, in some chemical reaction processes, pressure changes may occur, affecting the accuracy of the differential pressure type liquid level measurement device. Content of the Utility Model

[0005] The purpose of the utility model is to provide a differential pressure type liquid level measurement device for fine chemical industry, which can measure the liquid level more accurately and has better anti-interference ability.

[0006] To achieve the above purpose, the utility model provides the following technical scheme:

[0007] A differential pressure type liquid level measurement device for fine chemical industry includes a differential pressure transmitter connected to a liquid container. The differential pressure transmitter includes a positive pressure chamber, a negative pressure chamber, two pressure sensors located in the positive pressure chamber and the negative pressure chamber, and a central processor connected to the two pressure sensors. The central processor collects the pressure data collected by the two pressure sensors and calculates, and finally outputs the liquid level data and displays it through a display screen;

[0008] The positive pressure chamber of the differential pressure transmitter is connected to the bottom end of the liquid container through a positive pressure conduit, and the negative pressure chamber of the differential pressure transmitter is connected to the upper air part of the liquid container through a negative pressure conduit;

[0009] A temperature sensor is provided at the lower part of the inner side wall of the liquid container, and the temperature sensor is electrically connected to the central processor of the differential pressure transmitter;

[0010] An air pressure sensor is provided at the upper part of the inner side wall of the liquid container, and the air pressure sensor is electrically connected to the central processing unit of the differential pressure transmitter through an electrical signal.

[0011] Note: A high-precision temperature sensor is added to the device to monitor the temperature change of the measurement environment in real time. According to the relationship between temperature and medium density, the measurement result is temperature-compensated through an algorithm to eliminate the influence of temperature change on the liquid level measurement accuracy.

[0012] Preferably, pipe joint expansion mechanisms are connected in series on both the positive pressure conduit and the negative pressure conduit. The pipe joint expansion mechanism includes a pipe joint expansion outer tube. One end of the pipe joint expansion outer tube is fixed with a series input pipe connected to it. A pipe joint expansion piston is slidably connected inside the pipe joint expansion outer tube. The pipe joint expansion piston has an output pipe fixing hole penetrating along the axis of the pipe joint expansion outer tube, and a series output pipe penetrating through the other end of the pipe joint expansion outer tube is fixed in the output pipe fixing hole;

[0013] A telescopic drive support seat is fixed on the outside of the pipe joint expansion outer tube. The telescopic drive support seat has a telescopic drive mating hole penetrating along the axis parallel to the pipe joint expansion outer tube. A telescopic drive threaded rod is threadedly connected in the telescopic drive mating hole. A telescopic mating support seat is fixed on the outside of the series output pipe, and the end of the telescopic drive threaded rod is connected to the telescopic mating support seat through a ball hinge.

[0014] Note: The pipe joint expansion mechanism is used to improve the installation method, making it convenient to adjust the length of the positive pressure conduit and the negative pressure conduit during installation and commissioning, and facilitating on-site installation and commissioning.

[0015] Preferably, an electric heating grid is provided in the positive pressure chamber, and the pressure sensor in the positive pressure chamber has a ceramic coating.

[0016] Note: For easily crystallized measured media, setting a special ceramic coating on the surface of the pressure sensor and setting an electric heating grid near the pressure sensor can effectively prevent the formation of crystallization substances and avoid affecting the measurement accuracy.

[0017] Preferably, a positive pressure pipe cleaning input pipe is connected and communicated at one end of the positive pressure conduit close to the liquid container. A first control valve is provided on the positive pressure pipe cleaning input pipe. A positive pressure pipe cleaning output pipe is connected and communicated at one end of the positive pressure conduit close to the differential pressure transmitter. A second control valve is provided on the positive pressure pipe cleaning output pipe;

[0018] A negative pressure pipe cleaning input pipe is connected and communicated at one end of the negative pressure conduit close to the liquid container. A third control valve is provided on the negative pressure pipe cleaning input pipe. A negative pressure pipe cleaning output pipe is connected and communicated at one end of the negative pressure conduit close to the differential pressure transmitter. A fourth control valve is provided on the negative pressure pipe cleaning output pipe.

[0019] Description: A connecting pipe for cleaning is provided on the positive pressure conduit and the negative pressure conduit, which facilitates the cleaning of the inside of the positive pressure conduit and the negative pressure conduit, avoids blockage of the pipeline caused by the measured medium with high viscosity, and affects the measurement accuracy.

[0020] Preferably, an electromagnetic shielding case is fixedly surrounded outside the differential pressure transmitter. The inner side wall of the electromagnetic shielding case is fixedly connected with a plurality of electromagnetic shielding aluminum foils through fixing short columns, and the electromagnetic shielding aluminum foils are densely arranged in the electromagnetic shielding case.

[0021] Description: An electromagnetic shielding device is provided around the differential pressure transmitter to reduce the influence of external electromagnetic interference on the measurement result.

[0022] Compared with the prior art, the beneficial effects of the present utility model are reflected in the following aspects:

[0023] 1. The structure of the present utility model is reasonably designed. A high-precision temperature sensor is provided in the liquid container to monitor the temperature change of the measurement environment in real time. According to the relationship between temperature and medium density, the measurement result is temperature-compensated through an algorithm, which facilitates eliminating the influence of temperature change on the liquid level measurement accuracy;

[0024] 2. The present utility model is provided with a high-precision air pressure sensor in the liquid container. If the pressure in the container is unstable, it will also interfere with the measurement result of the pressure sensor. For example, in some chemical reaction processes, pressure changes may occur. The air pressure sensor is used to monitor the change of air pressure in the liquid container in real time, and the measurement result is corrected through an algorithm to improve the accuracy of the measurement result;

[0025] 3. The present utility model adopts a pipe joint telescopic mechanism to improve the installation method, so that the positive pressure conduit and the negative pressure conduit are convenient for length adjustment during installation and debugging, and it is convenient for on-site installation and debugging;

[0026] 4. For the easily crystallized measured medium, the present utility model sets a special ceramic coating on the surface of the pressure sensor and an electric heating network near the pressure sensor, which can effectively prevent the formation of crystals and avoid affecting the measurement accuracy;

[0027] 5. An electromagnetic shielding case is provided around the differential pressure transmitter, and a plurality of electromagnetic shielding aluminum foils are densely arranged in the electromagnetic shielding case, which can effectively reduce the influence of external electromagnetic interference on the measurement result. Description of the Drawings

[0028] Figure 1 is the front view of the present utility model;

[0029] Figure 2 is the structural schematic diagram of the pipe joint telescopic mechanism of the present utility model;

[0030] Figure 3This is a schematic structural diagram of the electromagnetic shielding case of the present utility model.

[0031] In the figure, 10 is a liquid container, 11 is a temperature sensor, 12 is a pressure sensor, 20 is a differential pressure transmitter, 201 is a positive pressure chamber, 202 is a negative pressure chamber, 21 is a positive pressure conduit, 22 is a negative pressure conduit, 23 is a pipe joint expansion mechanism, 231 is an outer pipe for pipe joint expansion, 232 is a series input pipe, 233 is a pipe joint expansion piston, 2330 is an output pipe fixing hole, 234 is a series output pipe, 235 is an expansion drive support base, 2350 is an expansion drive mating hole, 236 is an expansion drive threaded rod, 237 is an expansion mating support base, 238 is a ball hinge, 24 is an electric heating mesh, 251 is a positive pressure pipe cleaning input pipe, 2510 is a first control valve, 252 is a positive pressure pipe cleaning output pipe, 2520 is a second control valve, 253 is a negative pressure pipe cleaning input pipe, 2530 is a third control valve, 254 is a negative pressure pipe cleaning output pipe, 2540 is a fourth control valve, 26 is an electromagnetic shielding case, 261 is a fixed short column, and 262 is an electromagnetic shielding aluminum foil. Detailed implementation mode

[0032] The following combines Figures 1-3 to describe the present utility model in detail. For the convenience of narration, the directions mentioned below are defined as follows: the up, down, left, right, front, and back directions mentioned below are consistent with the up, down, left, right, front, and back directions of the projection relationship of each main view or structural schematic diagram itself.

[0033] Embodiment 1:

[0034] A differential pressure type liquid level measuring device for fine chemicals, as Figure 1 shown, includes a differential pressure transmitter 20 connected to a liquid container 10. The differential pressure transmitter 20 includes a positive pressure chamber 201, a negative pressure chamber 202, two pressure sensors located in the positive pressure chamber 201 and the negative pressure chamber 202, and a central processor connected to the two pressure sensors. The central processor collects the pressure data collected by the two pressure sensors and calculates, and finally outputs the liquid level data and displays it through a display screen; (Note that the differential pressure transmitter 20 used in the present utility model is a differential pressure transmitter of the prior art, and the present application does not make any improvements to the structure of the differential pressure transmitter 20)

[0035] The positive pressure chamber 201 of the differential pressure transmitter 20 is connected to the bottom end of the liquid container 10 through a positive pressure conduit 21, and the negative pressure chamber 202 of the differential pressure transmitter 20 is connected to the upper air part of the liquid container 10 through a negative pressure conduit 22;

[0036] A temperature sensor 11 is provided at the lower part of the inner side wall of the liquid container 10, and the temperature sensor 11 is electrically connected to the central processor of the differential pressure transmitter 20; (Note that this connection method belongs to a mature communication connection method of the prior art, and the present application does not make improvements to this connection method)

[0037] An air pressure sensor 12 is provided at the upper part of the inner side wall of the liquid container 10. The air pressure sensor 12 is installed at the position of the air part at the top inside the liquid container 10. The air pressure sensor 12 is electrically connected to the central processing unit of the differential pressure transmitter 20. (Note that this connection method belongs to a mature communication connection method in the prior art, and this application does not make improvements to this connection method).

[0038] As Figure 1 shown, pipe joint expansion and contraction mechanisms 23 are serially provided on both the positive pressure conduit 21 and the negative pressure conduit 22. As Figure 2 shown, the pipe joint expansion and contraction mechanism 23 includes a pipe joint expansion and contraction outer tube 231. One end of the pipe joint expansion and contraction outer tube 231 is fixed with a series input pipe 232 communicated with it. A pipe joint expansion and contraction piston 233 is slidably connected inside the pipe joint expansion and contraction outer tube 231. The pipe joint expansion and contraction piston 233 has an output pipe fixing hole 2330 penetrating along the axis of the pipe joint expansion and contraction outer tube 231. A series output pipe 234 penetrating through the other end of the pipe joint expansion and contraction outer tube 231 is fixed in the output pipe fixing hole 2330;

[0039] The pipe joint expansion and contraction mechanism 23 divides the positive pressure conduit 21 and the negative pressure conduit 22 into two sections.

[0040] For the pipe joint expansion and contraction mechanism 23 connected to the positive pressure conduit 21, the series input pipe 232 is communicated with one section of the positive pressure conduit 21, and the series output pipe 234 is communicated with the other section of the positive pressure conduit 21;

[0041] For the pipe joint expansion and contraction mechanism 23 connected to the negative pressure conduit 22, the series input pipe 232 is communicated with one section of the negative pressure conduit 22, and the series output pipe 234 is communicated with the other section of the negative pressure conduit 22;

[0042] A telescopic drive support base 235 is fixed on the outer side of the pipe joint expansion and contraction outer tube 231. The telescopic drive support base 235 has a telescopic drive mating hole 2350 penetrating along the axis parallel to the pipe joint expansion and contraction outer tube 231. A telescopic drive threaded rod 236 is in threaded transmission connection in the telescopic drive mating hole 2350. A telescopic mating support base 237 is fixed on the outer side of the series output pipe 234. The end of the telescopic drive threaded rod 236 is connected to the telescopic mating support base 237 through a ball hinge 238.

[0043] As Figure 3 shown, an electric heating grid 24 is provided in the positive pressure chamber 201. The pressure sensor in the positive pressure chamber 201 has a zirconia ceramic coating of the prior art.

[0044] Example 2:

[0045] On the basis of Example 1, as Figure 1As shown in the figure, one end of the positive pressure conduit 21 close to the liquid container 10 is communicatively connected with a positive pressure pipe cleaning input pipe 251. A first control valve 2510 is provided on the positive pressure pipe cleaning input pipe 251. One end of the positive pressure conduit 21 close to the differential pressure transmitter 20 is communicatively connected with a positive pressure pipe cleaning output pipe 252. A second control valve 2520 is provided on the positive pressure pipe cleaning output pipe 252;

[0046] One end of the negative pressure conduit 22 close to the liquid container 10 is communicatively connected with a negative pressure pipe cleaning input pipe 253. A third control valve 2530 is provided on the negative pressure pipe cleaning input pipe 253. One end of the negative pressure conduit 22 close to the differential pressure transmitter 20 is communicatively connected with a negative pressure pipe cleaning output pipe 254. A fourth control valve 2540 is provided on the negative pressure pipe cleaning output pipe 254.

[0047] Embodiment 3:

[0048] Based on Embodiment 2, as Figure 3 shown in the figure, an electromagnetic shielding case 26 is fixedly surrounded outside the differential pressure transmitter 20. A plurality of electromagnetic shielding aluminum foils 262 are fixedly connected to the inner side wall of the electromagnetic shielding case 26 through fixing studs 261. The electromagnetic shielding aluminum foils 262 are densely arranged in the electromagnetic shielding case 26.

[0049] It should be noted that the differential pressure transmitter 20 and its internal structure in each embodiment of the present application are prior art. The temperature sensor 11, the air pressure sensor 12, the electric heating grid 24, and the electromagnetic shielding aluminum foils 262 are also all products using prior art. The first control valve 2510, the second control valve 2520, the third control valve 2530, and the fourth control valve 2540 are all direct-flow single-seat control valves in the prior art, and no special limitation is made here. Those skilled in the art can select according to needs as long as the technical solutions of the present application can be realized.

[0050] In the actual application process of the present utility model, the pressure sensor in the positive pressure chamber 201 is used to measure the pressure at the bottom of the liquid container 10. The pressure sensor in the negative pressure chamber 202 is used to measure the gas phase pressure of the air part at the upper end of the liquid container 10. By subtracting the two pressures, the pressure difference purely generated by the liquid level height is obtained. According to the relationship formula between the pressure difference and the liquid level height, the liquid level height can be accurately calculated;

[0051] A high-precision temperature sensor 11 is provided in the liquid container 10 to monitor the temperature change of the measurement environment in real time. According to the relationship between temperature and medium density, the measurement result is temperature-compensated through an algorithm to facilitate eliminating the influence of temperature change on the liquid level measurement accuracy;

[0052] A high-precision barometric pressure sensor 12 is set at the air part position at the top inside the liquid container 10. If the pressure inside the container is unstable, it will also interfere with the measurement results of the pressure sensor. For example, during some chemical reaction processes, pressure changes may occur. The barometric pressure sensor 12 is used to monitor the change of the air pressure inside the liquid container 10 in real time, and the measurement results are corrected through an algorithm to improve the accuracy of the measurement results;

[0053] During the actual installation process, the pipe joint telescopic mechanism 23 enables the positive pressure conduit 21 and the negative pressure conduit 22 to be convenient for length adjustment during installation and debugging, facilitating on-site installation and debugging;

[0054] One end of the telescopic drive threaded rod 236 away from the telescopic fit support seat 237 has an internal hexagonal hole. By using an internal hexagonal tool to drive the telescopic drive threaded rod 236 to rotate, the telescopic drive threaded rod 236 can drive the series output pipe 234 together with the pipe joint telescopic piston 233 to move along the axis direction of the pipe joint telescopic outer pipe 231 through the telescopic fit support seat 237, thereby adjusting the length formed by the series input pipe 232, the pipe joint telescopic outer pipe 231 and the series output pipe 234 as a whole;

[0055] Moreover, the telescopic drive threaded rod 236 is in threaded transmission connection with the telescopic drive fit hole 2350 and has a self-locking function to prevent the series output pipe 234 from moving by itself under the action of liquid pressure;

[0056] For easily crystallized measured media, a special ceramic coating is set on the surface of the pressure sensor in the positive pressure chamber 201, and an electric heating net 24 is set near the pressure sensor. The electric heating net 24 is powered on to appropriately heat the liquid in the positive pressure chamber 201 to prevent the liquid from forming crystals on the pressure sensor, thereby avoiding affecting the measurement accuracy;

[0057] During the normal working process, the first control valve 2510, the second control valve 2520, the third control valve 2530 and the fourth control valve 2540 are all in the closed state;

[0058] After the liquid container 10 has contained a liquid with a relatively high viscosity, it is necessary to clean the positive pressure conduit 21 to prevent the relatively high-viscosity liquid from drying and blocking the positive pressure conduit 21. Open the first control valve 2510 and the second control valve 2520, and use a delivery pump to input water into the positive pressure pipe cleaning input pipe 251. The water in the positive pressure pipe cleaning input pipe 251 enters the positive pressure conduit 21 and flows towards the positive pressure pipe cleaning output pipe 252, and the cleaned wastewater can be discharged from the positive pressure pipe cleaning output pipe 252.

Claims

1. A differential pressure type liquid level measuring device for fine chemicals, comprising a differential pressure transmitter (20) connected to a liquid container (10), the differential pressure transmitter (20) including a positive pressure chamber (201), a negative pressure chamber (202), two pressure sensors located in the positive pressure chamber (201) and the negative pressure chamber (202), and a central processor connected to the two pressure sensors, characterized in that, The positive pressure chamber (201) of the differential pressure transmitter (20) is connected to the bottom end of the liquid container (10) through a positive pressure conduit (21), and the negative pressure chamber (202) of the differential pressure transmitter (20) is connected to the upper air part of the liquid container (10) through a negative pressure conduit (22); A temperature sensor (11) is provided at the lower part of the inner side wall of the liquid container (10), and the temperature sensor (11) is electrically connected to the central processor of the differential pressure transmitter (20); An air pressure sensor (12) is provided at the upper part of the inner side wall of the liquid container (10), and the air pressure sensor (12) is electrically connected to the central processor of the differential pressure transmitter (20).

2. The differential pressure type liquid level measuring device for fine chemicals according to claim 1, characterized in that, Pipe joint expansion mechanisms (23) are connected in series on both the positive pressure conduit (21) and the negative pressure conduit (22). The pipe joint expansion mechanism (23) includes a pipe joint expansion outer tube (231). One end of the pipe joint expansion outer tube (231) is fixed with a series input pipe (232) communicated therewith. A pipe joint expansion piston (233) is slidably connected in the pipe joint expansion outer tube (231). The pipe joint expansion piston (233) has an output pipe fixing hole (2330) penetrating along the axis of the pipe joint expansion outer tube (231). A series output pipe (234) passing through the other end of the pipe joint expansion outer tube (231) is fixed in the output pipe fixing hole (2330); A telescopic drive support base (235) is fixed on the outer side of the pipe joint expansion outer tube (231). The telescopic drive support base (235) has a telescopic drive mating hole (2350) penetrating along a direction parallel to the axis of the pipe joint expansion outer tube (231). A telescopic drive threaded rod (236) is in threaded transmission connection in the telescopic drive mating hole (2350). A telescopic mating support base (237) is fixed on the outer side of the series output pipe (234). The end of the telescopic drive threaded rod (236) is connected to the telescopic mating support base (237) through a ball hinge (238).

3. A differential pressure type liquid level measuring device for fine chemicals according to claim 1, characterized in that, An electric heating mesh (24) is provided in the positive pressure chamber (201), and the pressure sensor in the positive pressure chamber (201) has a ceramic coating.

4. A differential pressure type liquid level measuring device for fine chemicals according to claim 1, characterized in that, One end of the positive pressure conduit (21) close to the liquid container (10) is communicated with a positive pressure pipe cleaning input pipe (251), and a first control valve (2510) is provided on the positive pressure pipe cleaning input pipe (251). One end of the positive pressure conduit (21) close to the differential pressure transmitter (20) is communicated with a positive pressure pipe cleaning output pipe (252), and a second control valve (2520) is provided on the positive pressure pipe cleaning output pipe (252); One end of the negative pressure conduit (22) close to the liquid container (10) is communicated with a negative pressure pipe cleaning input pipe (253), and a third control valve (2530) is provided on the negative pressure pipe cleaning input pipe (253). One end of the negative pressure conduit (22) close to the differential pressure transmitter (20) is communicated with a negative pressure pipe cleaning output pipe (254), and a fourth control valve (2540) is provided on the negative pressure pipe cleaning output pipe (254).

5. A differential pressure type liquid level measuring device for fine chemicals according to claim 1, characterized in that, An electromagnetic shielding case (26) is fixedly disposed around the outside of the differential pressure transmitter (20). A plurality of electromagnetic shielding aluminum foils (262) are fixedly connected to the inner side wall of the electromagnetic shielding case (26) through fixing short columns (261), and the electromagnetic shielding aluminum foils (262) are densely arranged in the electromagnetic shielding case (26).

Images