Liquid level control system for ammonia water environment

Abstract

The invention relates to the technical field of liquid level control, in particular to a liquid level control system for an ammonia water environment, which comprises an ammonia water tank, an ammonia water pump, a liquid level sensor and a logic controller, the ammonia water tank is provided with a liquid inlet and a liquid outlet; a liquid inlet of the ammonia water tank is connected with a liquid outlet of the ammonia water pump; the liquid level sensor is arranged on the ammonia water tank; the logic controller is in communication connection with the ammonia water pump and the liquid level sensor; the liquid level sensor senses the liquid level of ammonia water in the ammonia water tank and sends a signal to the logic controller, and the logic controller sends an instruction to control whether the ammonia water pump supplements the ammonia water to the ammonia water tank or not. The liquid level in the ammonia water tank is synchronously controlled through two different control modes, the stability and reliability of ammonia water control are improved, and long-period safe operation is ensured.

Description

Technical Field

[0001] This invention relates to the field of liquid level control technology, and more specifically to a liquid level control system for ammonia water environments. Background Technology

[0002] Ammonia dissolves in water to form ammonia water, which is alkaline. Alkaline substances are corrosive, and the corrosive hazards of ammonia water are multifaceted, causing damage to materials and equipment. Corrosion of metallic materials: Ammonia can react chemically with many metals, leading to their corrosion. For example, ammonia can react with copper and its alloys to form copper-ammonia complex ions, accelerating copper corrosion. Damage to non-metallic materials: Ammonia is also corrosive to non-metallic materials such as rubber and plastics. Long-term contact can cause changes in the physical properties of these materials, such as softening and loss of elasticity. Damage to equipment and pipelines: In industrial production, the corrosiveness of ammonia can lead to leaks in equipment and pipelines, increasing the risk of safety accidents. For example, ammonia can react with steel to produce hydrogen gas, causing stress corrosion cracking.

[0003] Ammonia water is usually stored in ammonia water tanks. The simplest and lowest cost liquid level control technology currently available is float / float switch control, which is the most common type of control. The principle is to use buoyancy. The float rises and falls with the liquid level, driving the linkage or magnetic reed switch to control the liquid inlet pump and liquid inlet valve. Ammonia water is corrosive to the float / float, and long-term contact will cause the float / float to corrode and be damaged.

[0004] A malfunction of the level controller during production may lead to ammonia overflow, causing serious consequences such as environmental pollution, fire, and explosion. Therefore, stable control equipment must be used to control the level of ammonia in order to prevent accidents. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a liquid level control system for ammonia water environments, which can prevent corrosion and damage to the liquid level controller in ammonia water environments and provide a safe, stable, and reliable automatic control system.

[0006] The present invention provides a liquid level control system for an ammonia water environment, comprising an ammonia water tank, an ammonia water pump, a liquid level sensor, and a logic controller; The ammonia tank is provided with an inlet and an outlet; the inlet of the ammonia tank is connected to the outlet of the ammonia pump; the liquid level sensor is installed on the ammonia tank. The logic controller is communicatively connected to the ammonia pump and the level sensor. The level sensor senses the ammonia level in the ammonia tank and sends a signal to the logic controller. The logic controller then issues a command to control whether the ammonia pump replenishes the ammonia tank with ammonia.

[0007] Furthermore, a sleeve is installed on the top of the ammonia tank, and an insulating plate is installed on the sleeve; The liquid level sensor includes a first detection column, a second detection column, a third detection column, and a liquid level controller; the first, second, and third detection columns are all mounted on an insulating plate. The first probe has a first terminal block at its first end and a first probe at its second end; the second probe has a second terminal block at its first end and a second probe at its second end; the third probe has a third terminal block at its first end and a third probe at its second end; the position of the first probe is lower than the position of the second probe; the position of the second probe is lower than the position of the first probe. The first terminal, the second terminal, and the third terminal are all connected to the level controller via connecting wires; the level controller is connected to the logic controller.

[0008] Furthermore, a probe insertion hole is provided at the second end of the first probe post, and a set screw fixing hole is provided in the first probe post that communicates with the probe insertion hole; the first probe is located in the probe insertion hole, and a set screw for fixing the first probe is provided in the fixing hole.

[0009] Furthermore, the ammonia pump includes a U-end, a V-end, and a W-end; the U-end is connected to the L1 end of an external power supply via a motor protector and a first connecting line; the V-end is connected to the L2 end of an external power supply via a second connecting line; and the W-end is connected to the L3 end of an external power supply via a motor protector and a third connecting line. The first terminal of the motor protector is connected to the L3 terminal of the external power supply; the second and third terminals of the motor protector are connected to the neutral wire of the external power supply; the third and fourth terminals of the motor protector are connected to the logic controller respectively. The L3 terminal of the external power supply is connected to the liquid level controller through a voltage conversion circuit to provide the liquid level controller with the second voltage required by the liquid level controller; the L3 terminal of the external power supply is connected to the logic controller to provide the logic controller with the first voltage required by the logic controller.

[0010] Furthermore, the voltage conversion circuit includes capacitor C1, capacitor C2, resistor R, diode D1, diode D2, and diode D3; One end of resistor R is connected to the L3 terminal of the external power supply, and the other end of resistor R is connected to one end of diode D2. The other end of diode D2 is connected to the liquid level controller to provide the liquid level controller with the required second voltage. One end of capacitor C1 is connected to one end of resistor R, and the other end of capacitor C1 is connected to the other end of resistor R. The other end of resistor R is grounded through diode D1, the other end of diode D2 is grounded through diode D3, one end of capacitor C2 is connected to the other end of diode D2, and the other end of capacitor C2 is grounded.

[0011] Furthermore, the liquid level controller includes a first terminal block, a second terminal block, a fourth terminal block, a seventh terminal block, and an eighth terminal block; The first terminal of the level controller is connected to the third terminal, the eighth terminal of the level controller is connected to the second terminal, and the seventh terminal of the level controller is connected to the first terminal; the second terminal of the level controller is connected to the voltage conversion circuit, and the fourth terminal of the level controller is connected to the first terminal of the logic controller.

[0012] Furthermore, when the liquid level in the ammonia tank is lower than the second probe, the first terminal is disconnected from the eighth terminal, making the second terminal connected to the fourth terminal. The first terminal of the logic controller is energized, and the logic controller receives the low liquid level switch signal from the liquid level controller. The logic controller then issues a command to start the ammonia pump to replenish the ammonia tank. When the liquid level in the ammonia tank is higher than the first probe, the first terminal and the seventh terminal are connected, causing the second terminal and the fourth terminal to disconnect. The first terminal of the logic controller is de-energized. The logic controller receives the high liquid level switch signal from the liquid level controller and issues a command to stop the ammonia pump from replenishing the ammonia tank.

[0013] Furthermore, it also includes a first differential pressure transmitter and a second differential pressure transmitter. The first differential pressure transmitter and the second differential pressure transmitter are respectively connected to the ammonia tank. The ammonia tank is provided with a first source point and a second source point. The first differential pressure transmitter is used to obtain a first pressure value at the first source point, and the second differential pressure transmitter is used to obtain a second pressure value at the second source point. The second source point is located above the first source point.

[0014] Furthermore, the first differential pressure transmitter and the second differential pressure transmitter are electrically connected to the logic controller. The first differential pressure transmitter outputs a first pressure value to the logic controller, and the second differential pressure transmitter sends a second pressure value to the logic controller. The logic controller calculates the pressure difference of the ammonia tank in real time based on the first and second pressure values. Based on the pressure difference, the logic controller can also issue instructions to control whether the ammonia pump replenishes ammonia to the ammonia tank.

[0015] The beneficial effects of this invention are: This invention avoids the corrosion damage to conventional liquid level detection elements caused by the corrosiveness of ammonia water. It provides a switching quantity for the liquid level controller and an analog quantity for the differential pressure value of the first and second differential pressure transmitters. Two different control methods are used to synchronously control the liquid level in the ammonia water tank. If one control method fails, the second control method can ensure the normal operation of the system, thereby improving the stability and reliability of ammonia water control and ensuring long-term safe operation. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the liquid level control system of the present invention; Figure 2 This is a control principle diagram of the present invention; Figure 3 This is the instruction logic control flowchart of the present invention.

[0018] Explanation of reference numerals in the attached figures E1: First probe E2: Second probe E3: Third probe UDK: Level Controller P1: First differential pressure transmitter P2: Second differential pressure transmitter PLC: Logic Controller OP: Host computer QF: Air circuit breaker KM: AC contactor EOCR: Motor Protector M: Ammonia pump FU: Fuse 1: First terminal 2: Sleeve 3: Threading hole 4: Insulation board 5: Ammonia tank Logic controller terminal labels: 6: First terminal 7: Second terminal 8: Third terminal 9: Fourth terminal 10: Fifth terminal 11: Sixth terminal 12: Seventh terminal 13: Eighth terminal. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Many specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] The purpose of this invention is to provide a liquid level control system for ammonia water environments, which can avoid corrosion and damage to the liquid level controller in ammonia water environments and provide a safe, stable, and reliable automatic control system.

[0021] Example 1:

[0022] The present invention provides a liquid level control system for an ammonia water environment, comprising an ammonia water tank 5, an ammonia water pump M, a liquid level sensor UDK, and a logic controller PLC.

[0023] The ammonia tank 5 is equipped with an inlet and an outlet; the height of the inlet is higher than the height of the outlet. The inlet of the ammonia tank 5 is connected to the outlet of the ammonia pump M, and the inlet of the ammonia pump M is connected to an external ammonia delivery pipeline, so that external ammonia can be delivered to the ammonia tank 5 through the ammonia pump M.

[0024] A liquid level sensor is installed on the ammonia tank 5; the logic controller PLC is electrically connected to the ammonia pump M and the liquid level sensor; the liquid level sensor senses the liquid level of ammonia in the ammonia tank 5 and sends a corresponding signal to the logic controller PLC, which then issues a corresponding instruction to control whether the ammonia pump M replenishes ammonia in the ammonia tank 5 according to the signal.

[0025] like Figure 1 As shown, a sleeve 2 is installed on the top of the ammonia tank 5, and an insulating plate 4 and a wire hole 3 are installed on the sleeve 2. The liquid level sensor includes a first detection column, a second detection column, a third detection column, and a liquid level controller UDK; the first detection column, the second detection column, and the third detection column are all installed on the insulating plate 4.

[0026] The first end of the first probe post is provided with a first terminal post 1, and the second end is provided with a probe insertion hole and a set screw fixing hole, the set screw fixing hole being connected to the probe insertion hole. The first probe E1 is located in the probe insertion hole, and a set screw is provided in the set screw fixing hole to fix the first probe E1.

[0027] Similarly, the first end of the second probe post is provided with a second terminal post, and the second end is provided with a probe insertion hole and a set screw fixing hole, the set screw fixing hole being connected to the probe insertion hole. The second probe E2 is located inside the probe insertion hole, and a set screw is provided inside the set screw fixing hole, the set screw being used to fix the second probe E2.

[0028] Similarly, the first end of the third probe post is provided with a third terminal post, and the second end is provided with a probe insertion hole and a set screw fixing hole, with the set screw fixing hole communicating with the probe insertion hole. The third probe E3 is located inside the probe insertion hole, and a set screw is provided inside the set screw fixing hole to fix the third probe E3.

[0029] The three probes have identical structures, but the first probe E1 is positioned higher than the second probe E2, and the second probe E2 is positioned higher than the third probe E3. Since the three probes are fixed using insert bolts, their positions can be adjusted according to the specific liquid level to control the ammonia level in the ammonia tank 5. In this embodiment, the sleeve, probes, and set screws are made of conductive titanium.

[0030] The first terminal 1, the second terminal, and the third terminal are all located above the insulating plate 4, and are respectively connected to the level controller UDK through connecting wires passing through the wiring hole 3; the level controller UDK is connected to the logic controller PLC. The level controller UDK can be placed in the same area as the logic controller PLC. In this embodiment, the specific placement of the level controller UDK is not specifically limited.

[0031] The consumption of ammonia water will cause the first probe E1 and the second probe E2 to change inside and outside the liquid level. The conductivity of the first probe E1 and the second probe E2 in the liquid will be used to control the liquid level controller UDK to send a switch signal to the logic controller PLC. The logic controller PLC will issue an execution instruction based on the switch signal to control whether the ammonia water pump M replenishes ammonia water to the ammonia water tank 5.

[0032] The ammonia pump M includes a U-end, a V-end, and a W-end; the U-end is connected to the L1 end of the external power supply via the motor protector EOCR and the first connecting line; the V-end is connected to the L2 end of the external power supply via the second connecting line; the W-end is connected to the L3 end of the external power supply via the motor protector EOCR and the third connecting line; the L3 end of the external power supply is connected to the first end of the motor protector EOCR via a fuse FU. The second and third terminals of the motor protector EOCR are connected to the neutral wire of the external power supply. The third terminal of the motor protector EOCR is connected to the second terminal 7 of the logic controller PLC. The fourth terminal of the motor protector EOCR is connected to the third terminal 8 of the logic controller PLC through the AC contactor KM.

[0033] The L3 terminal of the external power supply is also connected to a voltage conversion circuit via a fuse FU. The voltage conversion circuit is connected to the level controller UDK, providing the level controller UDK with the second voltage required by the level controller UDK. The L3 terminal of the external power supply is also connected to the fourth terminal 9 and the fifth terminal 10 of the logic controller PLC via a fuse FU, providing the logic controller PLC with the first voltage required by the logic controller PLC.

[0034] like Figure 2 As shown, the voltage conversion circuit includes capacitor C1, capacitor C2, resistor R, diodes D1, D2, and D3. One end of resistor R is connected to the L3 terminal of the external power supply through fuse FU, and the other end of resistor R is connected to one end of diode D2. The other end of diode D2 outputs a second voltage to the second terminal of the level controller UDK. One end of capacitor C1 is connected to one end of resistor R, and the other end of capacitor C1 is connected to the other end of resistor R. The other end of resistor R is grounded through diode D1, and the other end of diode D2 is grounded through diode D3. One end of capacitor C2 is connected to the other end of diode D2, and the other end of capacitor C2 is grounded.

[0035] The level controller UDK includes a first terminal, a second terminal, a fourth terminal, a seventh terminal, and an eighth terminal. The first terminal of the level controller UDK is connected to the third terminal, the eighth terminal of the level controller UDK is connected to the second terminal, and the seventh terminal of the level controller UDK is connected to the first terminal 1. The second terminal of the level controller UDK is connected to the voltage conversion circuit, and the fourth terminal of the level controller UDK is connected to the first terminal 6 of the logic controller PLC.

[0036] Preferably, the logic controller (PLC) is a programmable logic controller (PLC). The PLC selected is a Siemens 224XPCN, whose CPU module has 14 digital input channels, 10 digital output channels (all relay-type outputs), 2 analog input channels, and 1 analog output channel. The PLC can also connect to a host computer (OP) via its built-in RS232 / 485 port, allowing real-time modification of the PLC program and the OP control screen. The OP screen displays the real-time status of the liquid level control system, including the start / stop status of ammonia pump M, the real-time level of ammonia tank 5, and the high / low alarm status of the level controller UDK. The screen also includes high and low level limit setting windows. To ensure system safety, a stop button is provided on the screen; pressing the stop button immediately stops ammonia pump M, and this stop button has higher priority than the start condition of ammonia pump M.

[0037] When the liquid level in ammonia tank 5 is lower than the second probe E2, the first terminal is disconnected from the eighth terminal, making the second terminal connected to the fourth terminal. The first terminal 6 of the logic controller PLC is energized. The logic controller PLC receives the low liquid level switch signal from the liquid level controller UDK and sends a command to start the ammonia pump M to replenish ammonia tank 5. When the liquid level in ammonia tank 5 is higher than the first probe E1, the first terminal and the seventh terminal are connected, causing the second terminal and the fourth terminal to disconnect. The first terminal 6 of the logic controller PLC is de-energized. The logic controller PLC receives the high liquid level switch signal from the liquid level controller UDK and issues a command to stop the ammonia pump M from replenishing ammonia tank 5.

[0038] Example 2:

[0039] In this embodiment, the level control system further includes a first differential pressure transmitter P1 and a second differential pressure transmitter P2. The ammonia tank 5 is provided with a first pressure source point and a second pressure source point. The first differential pressure transmitter P1 is connected to the first pressure source point of the ammonia tank 5 and is used to acquire a first pressure value at the first pressure source point. The second differential pressure transmitter P2 is connected to the second pressure source point of the ammonia tank 5 and is used to acquire a second pressure value at the second pressure source point; the second pressure source point is located above the first pressure source point.

[0040] The first port of the first differential pressure transmitter P1 and the first port of the second differential pressure transmitter P2 are both connected to the sixth terminal 11 of the logic controller PLC. The second port of the first differential pressure transmitter P1 is connected to the seventh terminal 12 of the logic controller PLC. The second port of the second differential pressure transmitter P2 is connected to the eighth terminal 13 of the logic controller PLC.

[0041] The first differential pressure transmitter P1 and the second differential pressure transmitter P2 are respectively connected to the logic controller PLC. The first differential pressure transmitter P1 outputs a first pressure value to the logic controller PLC, and the second differential pressure transmitter P2 sends a second pressure value to the logic controller PLC. The logic controller PLC calculates the pressure difference of the ammonia tank 5 in real time based on the first and second pressure values. Based on the pressure difference, the logic controller PLC can also issue instructions to control whether the ammonia pump M replenishes ammonia.

[0042] Specifically, the first differential pressure transmitter P1 is installed at the bottom (or near the bottom) of the ammonia tank 5 to measure the total pressure (liquid level static pressure + gas phase pressure), and the first sampling point uses a titanium diaphragm. The second differential pressure transmitter P2 is installed at the top (or in the gas phase space) of the ammonia tank 5 to measure the gas phase pressure, and the second sampling point uses a titanium diaphragm.

[0043] The principle of a differential pressure transmitter is to measure ΔP = P1 - P2, while the formula for calculating the liquid level height h is: h = (P1 - P2) / ρ g. P1: Bottom pressure of ammonia tank 5 (absolute or gauge pressure, must be consistent with P2); P2: Top gas phase pressure of ammonia tank 5 (absolute or gauge pressure, must be consistent with P1); ρ: Liquid density; g: Gravitational acceleration. The first differential pressure transmitter P1 and the second differential pressure transmitter P2 can be either absolute pressure transmitters or gauge pressure transmitters. However, the pressure type of the first differential pressure transmitter P1 and the second differential pressure transmitter P2 must be consistent. If both the first differential pressure transmitter P1 and the second differential pressure transmitter P2 are absolute pressure transmitters, simply subtract them; if both the first differential pressure transmitter P1 and the second differential pressure transmitter P2 are gauge pressure transmitters, ensure that their reference atmospheric pressure is consistent; absolute pressure and gauge pressure cannot be mixed, otherwise it will lead to calculation errors. The signals (pressure values) output by the first differential pressure transmitter P1 and the second differential pressure transmitter P2 must be acquired synchronously. This ensures that within the same scan cycle of the logic controller (PLC), the pressure difference between the first differential pressure transmitter P1 and the second differential pressure transmitter P2 is calculated in real time by the difference calculation module (PLC's subtraction instruction), avoiding calculation errors caused by time differences. The installation position of the first differential pressure transmitter P1 must be below the minimum liquid level to ensure it is always submerged in liquid; the installation position of the second differential pressure transmitter P2 must avoid feed impact or condensate accumulation. The zero points of the first differential pressure transmitter P1 and the second differential pressure transmitter P2 must be calibrated periodically to avoid long-term drift leading to differential error.

[0044] Its working principle is as follows: The first differential pressure transmitter P1 detects the first pressure value in real time based on the first source point, and the second differential pressure transmitter P2 monitors the second pressure value in real time based on the second source point. The second pressure value is sent to the logic controller PLC in the form of a 4-20mA analog signal. The logic controller PLC calculates the current liquid level value and compares it with the set high and low limit values. Based on this, it issues an execution command to control whether the ammonia pump M replenishes ammonia.

[0045] like Figure 3 As shown, the control logic of the liquid level control system in the industrial production process is as follows: When the liquid level in ammonia tank 5 is lower than the second probe E2 (corresponding to...) Figure 3 When the "E2 probe" is activated, the level controller UDK receives a disconnect signal from its first and eighth terminals, and the second and fourth terminals of the level controller UDK become conductive. The first terminal 6 of the logic controller PLC is energized, and the logic controller PLC receives a low level switch signal detected by the level controller UDK. The logic controller PLC then issues a command to start the ammonia pump M to replenish ammonia tank 5. Simultaneously, the logic controller PLC calculates the ammonia level in real time based on the pressure values ​​detected by the two differential pressure transmitters. When the level in ammonia tank 5 is lower than the set lower limit, the logic controller PLC controls the third terminal 8 (Q0.0) to switch to logic state 1 through internal logic operations, and issues a command to start the ammonia pump M to replenish ammonia tank 5.

[0046] When the liquid level in ammonia tank 5 is higher than the first probe E1 (corresponding to...) Figure 3 When the "E1 probe" is activated, the level controller UDK receives the conduction signals of the first and seventh terminals, the second and fourth terminals of the level controller UDK are disconnected, and the first terminal 6 (I1.0 terminal) of the logic controller PLC is energized. The logic controller PLC receives the high level switch signal detected by the level controller UDK and issues a command to stop the ammonia pump M from replenishing ammonia tank 5. Simultaneously, the logic controller PLC calculates the ammonia level in real time through the pressure values ​​detected by the two differential pressure transmitters. When the level in ammonia tank 5 is higher than the set upper limit, the logic controller PLC controls the third terminal 8 (Q0.0) to switch to logic state 0 through internal logic operation, stops issuing commands, and thus stops the ammonia pump M.

[0047] The logic controller (PLC) is configured to start and stop the ammonia pump M, and start and stop buttons for the ammonia pump M are set in the host computer (OP). When the start and stop buttons on the OP display are activated, regardless of whether the switch signal from the level controller (UDK) and the analog signals detected by the first differential pressure transmitter (P1) and the second differential pressure transmitter (P2) meet the conditions for starting or stopping the ammonia pump M, the PLC immediately issues a start or stop output command, causing the ammonia pump M to change its operating state. Only when the start and stop button functions on the OP display are deactivated will the level control system revert to the above automatic control mode.

[0048] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A liquid level control system for ammonia water environments, characterized in that, Includes ammonia tank, ammonia pump, level sensor, and logic controller; The ammonia tank is provided with an inlet and an outlet; the inlet of the ammonia tank is connected to the outlet of the ammonia pump; the liquid level sensor is installed on the ammonia tank. The logic controller is communicatively connected to the ammonia pump and the level sensor. The level sensor senses the ammonia level in the ammonia tank and sends a signal to the logic controller. The logic controller then issues a command to control whether the ammonia pump replenishes the ammonia tank with ammonia.

2. A liquid level control system for ammonia water environment according to claim 1, characterized in that, A sleeve is installed on the top of the ammonia tank, and an insulating plate is installed on the sleeve; The liquid level sensor includes a first detection column, a second detection column, a third detection column, and a liquid level controller; the first, second, and third detection columns are all mounted on an insulating plate. The first probe has a first terminal block at its first end and a first probe at its second end; the second probe has a second terminal block at its first end and a second probe at its second end; the third probe has a third terminal block at its first end and a third probe at its second end; the position of the first probe is lower than the position of the second probe; the position of the second probe is lower than the position of the first probe. The first terminal, the second terminal, and the third terminal are all connected to the level controller via connecting wires; the level controller is connected to the logic controller.

3. A liquid level control system for an ammonia water environment according to claim 2, characterized in that, The second end of the first probe post is provided with a probe insertion hole, and the first probe post is provided with a set screw fixing hole communicating with the probe insertion hole; the first probe is located in the probe insertion hole, and a set screw for fixing the first probe is provided in the fixing hole.

4. A liquid level control system for an ammonia water environment according to claim 2, characterized in that, The ammonia pump includes a U-end, a V-end, and a W-end; the U-end is connected to the L1 terminal of the external power supply through a motor protector and a first connecting line; the V-end is connected to the L2 terminal of the external power supply through a second connecting line; and the W-end is connected to the L3 terminal of the external power supply through a motor protector and a third connecting line. The first terminal of the motor protector is connected to the L3 terminal of the external power supply; the second and third terminals of the motor protector are connected to the neutral wire of the external power supply; the third and fourth terminals of the motor protector are connected to the logic controller respectively. The L3 terminal of the external power supply is connected to the liquid level controller through a voltage conversion circuit to provide the liquid level controller with the second voltage required by the liquid level controller; the L3 terminal of the external power supply is connected to the logic controller to provide the logic controller with the first voltage required by the logic controller.

5. A liquid level control system for an ammonia water environment according to claim 4, characterized in that, The voltage conversion circuit includes capacitor C1, capacitor C2, resistor R, diode D1, diode D2, and diode D3; One end of resistor R is connected to the L3 terminal of the external power supply, and the other end of resistor R is connected to one end of diode D2. The other end of diode D2 is connected to the liquid level controller to provide the liquid level controller with the required second voltage. One end of capacitor C1 is connected to one end of resistor R, and the other end of capacitor C1 is connected to the other end of resistor R. The other end of resistor R is grounded through diode D1, the other end of diode D2 is grounded through diode D3, one end of capacitor C2 is connected to the other end of diode D2, and the other end of capacitor C2 is grounded.

6. A liquid level control system for an ammonia water environment according to claim 4, characterized in that, The liquid level controller includes a first terminal block, a second terminal block, a fourth terminal block, a seventh terminal block, and an eighth terminal block; The first terminal of the level controller is connected to the third terminal, the eighth terminal of the level controller is connected to the second terminal, and the seventh terminal of the level controller is connected to the first terminal; the second terminal of the level controller is connected to the voltage conversion circuit, and the fourth terminal of the level controller is connected to the first terminal of the logic controller.

7. A liquid level control system for an ammonia water environment according to claim 6, characterized in that, When the liquid level in the ammonia tank is lower than the second probe, the first terminal is disconnected from the eighth terminal, making the second terminal connected to the fourth terminal. The first terminal of the logic controller is energized, and the logic controller receives the low liquid level switch signal from the liquid level controller. The logic controller then issues a command to start the ammonia pump to replenish the ammonia tank. When the liquid level in the ammonia tank is higher than the first probe, the first terminal and the seventh terminal are connected, causing the second terminal and the fourth terminal to disconnect. The first terminal of the logic controller is de-energized. The logic controller receives the high liquid level switch signal from the liquid level controller and issues a command to stop the ammonia pump from replenishing the ammonia tank.

8. A liquid level control system for ammonia water environment according to claim 1, characterized in that, It also includes a first differential pressure transmitter and a second differential pressure transmitter. The first differential pressure transmitter and the second differential pressure transmitter are respectively connected to the ammonia tank. The ammonia tank is provided with a first sampling point and a second sampling point. The first differential pressure transmitter is used to obtain a first pressure value at the first sampling point, and the second differential pressure transmitter is used to obtain a second pressure value at the second sampling point. The second sampling point is located above the first sampling point.

9. A liquid level control system for an ammonia water environment according to claim 8, characterized in that, The first differential pressure transmitter and the second differential pressure transmitter are electrically connected to the logic controller. The first differential pressure transmitter outputs a first pressure value to the logic controller, and the second differential pressure transmitter sends a second pressure value to the logic controller. The logic controller calculates the pressure difference of the ammonia tank in real time based on the first and second pressure values. Based on the pressure difference, the logic controller can also issue instructions to control whether the ammonia pump replenishes ammonia to the ammonia tank.

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