Hydrophobic tank liquid level detection and hydrophobic control device

Abstract

The application relates to the technical field of automation detection and control, in particular to a hydrophobic tank liquid level detection and hydrophobic control device. The device comprises a steam pipeline, a low point of the steam pipeline is provided with a hydrophobic tank, a hydrophobic pipeline is connected between the hydrophobic tank and a hydrophobic expansion vessel interface, the hydrophobic pipeline is provided with a pneumatic hydrophobic valve, a temperature detection assembly comprises an upper temperature detection element and a lower temperature detection element, the upper temperature detection element is arranged at the upper part of the hydrophobic tank, and the lower temperature detection element is arranged at the lower part of the hydrophobic tank; a distributed control system is electrically connected with the signal output ends of the upper temperature detection element and the lower temperature detection element, is used for receiving temperature signals, and a control signal output end of the distributed control system is connected with the control end of the pneumatic hydrophobic valve. The device has low initial investment and small maintenance workload.

Description

Technical Field

[0001] This application relates to the field of automated detection and control technology, specifically to a hydrophobic tank level detection and hydrophobic control device. Background Technology

[0002] In modern industrial production processes, especially in power plants, steam pipelines need to promptly remove condensate from the steam during unit startup, low load, and shutdown (tripping) or ensure the steam superheat meets system operating requirements to prevent water hammer or corrosion and ensure the safe and economical operation of equipment and systems. For this purpose, condensate drain lines are installed at appropriate locations (e.g., low points) in the steam pipelines, and some of these drain lines are equipped with condensate tanks.

[0003] There are two types of condensate tanks installed on condensate lines. The first type is a gravity condensate tank installed to accelerate condensation during unit startup and low-load operation. These are installed on condensate lines for main steam and high-temperature reheat steam with high superheat. The condensate valves on these lines open and close according to the unit's operating status (start-up, shutdown) and load. During normal unit operation, these condensate tanks do not condense, so level detection is unnecessary. The second type of condensate tank is mainly installed at the condensate inlet of lines with low-temperature reheat steam, where the steam superheat is low during normal unit operation. Its function is the same as the first type, but during normal unit operation, due to the low superheat of the steam in the steam lines, condensate gradually forms in the condensate tank. When the condensate tank level reaches the set height, the DCS opens the corresponding pneumatic condensate valve and drains the liquid from the tank. After the liquid is drained, the DCS closes the condensate valve. The DCS system repeats this process when the condensate tank level reaches the set height again. Therefore, the second type of condensate tank needs to be equipped with a liquid level detection system. The DCS controls the opening and closing of the condensate valve after the condensate tank based on the detected liquid level signal to ensure the safety and economy of the system operation.

[0004] Conventional designs use level switches or electric contact level gauges to detect the liquid level in condensate tanks. However, these detection devices and their associated instruments and valves are expensive, resulting in high initial investment and a large amount of maintenance work. Summary of the Invention

[0005] In view of this, the present application provides a hydrophobic tank level detection and hydrophobic control device, which has low initial investment and low maintenance workload.

[0006] The first aspect of this application provides a hydrophobic tank level detection and hydrophobic control device, including: A steam pipeline, wherein a condensate tank is provided at the lowest point of the steam pipeline; A drainage pipeline is connected between the drainage tank and the drainage expansion container interface, and the drainage pipeline is equipped with a pneumatic drainage valve; A temperature detection assembly includes an upper temperature sensing element and a lower temperature sensing element, wherein the upper temperature sensing element is disposed at the upper part of the hydrophobic tank and the lower temperature sensing element is disposed at the lower part of the hydrophobic tank; The distributed control system has its signal input terminal electrically connected to the signal output terminals of the upper and lower temperature measuring elements for receiving temperature signals, and its control signal output terminal is connected to the control terminal of the pneumatic steam trap.

[0007] In one embodiment, both the upper and lower temperature sensing elements are externally threaded armored thermocouples, and the side wall of the condensate tank is provided with an internally threaded mounting seat. The upper and lower temperature sensing elements are installed by matching the internally threaded mounting seat with the external threads.

[0008] In one embodiment, the upper temperature sensing element is installed at 2 / 3 of the height of the hydrophobic tank, and the lower temperature sensing element is installed at 1 / 3 of the height of the hydrophobic tank.

[0009] In one embodiment, the hydrophobic conduit includes: The first drainage pipe is connected to the outlet of the drainage tank; The second drainage pipe is connected at one end to the outlet of the first drainage pipe and at the other end to the inlet of the pneumatic drainage valve. The third drainage pipe is connected to the outlet of the pneumatic drainage valve; A condensate drain hole is provided on the third condensate pipe, and its outlet is connected to the condensate expansion container interface.

[0010] In one embodiment, the drainage pipeline further includes a manual drainage valve disposed on the first drainage pipeline.

[0011] In one embodiment, the signal input terminal of the distributed control system is also connected to the valve status output terminal of the pneumatic steam trap, for receiving the fully open position signal and the fully closed position signal of the pneumatic steam trap.

[0012] In one embodiment, the distributed control system includes: The first comparator has its input terminal connected to the temperature signal output terminal of the upper temperature sensing element; The second comparator has its input terminal connected to the temperature signal output terminal of the lower temperature sensing element; A logic OR circuit, wherein the first input terminal is connected to the output terminal of the first comparator, and the second input terminal is connected to the output terminal of the second comparator; The monostable multivibrator has its reset terminal connected to the output terminal of the logic OR circuit via a logic pulse module, its set terminal connected to the output terminal of the logic OR circuit via a logic delay module, and its output terminal connected to the control terminal of the pneumatic steam trap.

[0013] In one embodiment, the distributed control system further includes: A logic delay module, the input of which is connected to the output of the second comparator; The first alarm signal output terminal is connected to the output terminal of the logic delay module; The second alarm signal output terminal is connected to the output terminal of the first comparator.

[0014] The first aspect of this application provides a condensate tank level detection and condensate control device. By installing a condensate tank at the low point of the steam pipeline and configuring a pneumatic condensate valve on the condensate line, combined with upper and lower temperature sensing elements and a distributed control system, the device indirectly detects the liquid level using temperature changes, replacing traditional level switches and reducing hardware costs. Since the temperature elements are directly inserted into the tank, heat loss from an external float is avoided, improving system economy. Simultaneously, the distributed control system achieves automated control, reducing manual intervention. Its initial investment is low, and maintenance workload is minimal. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a steam pipeline with a condensate tank and a condensate tank level detection according to an embodiment of this application; Figure 2 This is a schematic diagram of the installation of a temperature detection component provided in one embodiment of this application; Figure 3 This is a schematic diagram of the control logic of a hydrophobic tank level detection and hydrophobic control device provided in one embodiment of this application. Detailed Implementation

[0017] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0018] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0019] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0020] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0021] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0024] like Figure 1 As shown, this application provides a steam condensate drain line with a condensate tank and a condensate tank level detection diagram, including: Steam pipe 1, with a condensate tank 2 installed at the lowest point of steam pipe 1; A drainage pipeline is connected between the drainage tank 2 and the drainage expansion container interface 9. The drainage pipeline is equipped with a pneumatic drainage valve 6. The temperature detection assembly includes an upper temperature sensing element 10 and a lower temperature sensing element 11. The upper temperature sensing element 10 is disposed on the upper part of the condensate tank 2, and the lower temperature sensing element 11 is disposed on the lower part of the condensate tank 2. The distributed control system 12 has its signal input terminal electrically connected to the signal output terminals of the upper temperature measuring element 10 and the lower temperature measuring element 11, and is used to receive temperature signals. The control signal output terminal of the distributed control system 12 is connected to the control terminal of the pneumatic steam trap 6.

[0025] In the application, the device includes a steam pipeline 1, which has a condensate tank 2 at its lowest point for collecting steam condensate. A condensate drain line connects the condensate tank 2 to the condensate expansion tank interface 9. The condensate drain line is equipped with a pneumatic condensate drain valve 6 to control condensate discharge. The temperature detection component includes an upper temperature sensing element 10 and a lower temperature sensing element 11, which are respectively located at the upper and lower parts of the condensate tank 2 to detect the temperature of the medium inside the tank. The signal input terminal of the distributed control system 12 is electrically connected to the signal output terminals of the upper temperature sensing element 10 and the lower temperature sensing element 11 to receive temperature signals. Its control signal output terminal is connected to the control terminal of the pneumatic condensate drain valve 6 to realize automatic control based on temperature changes. For the temperature detection component, a thermocouple can be used as the measuring element to ensure rapid response to temperature changes. For the distributed control system 12, a programmable logic controller can be used to compare temperature signals and generate valve control commands.

[0026] During unit operation, the temperature detection component continuously monitors the temperature of the medium inside the condensate tank. Once the condensate in the condensate tank reaches and covers the sensing end of the lower temperature sensing element TE2, the temperature sensed by the lower temperature sensing element will drop rapidly. At this time, the DCS determines that the liquid in the condensate tank has reached the required discharge height and issues a command to open the drain valve of this condensate line. After a certain delay, the liquid in the condensate tank is drained, and the DCS then issues a reset valve opening command to close the drain valve. If the DCS measures that the condensate tank temperature has dropped to the set value and the drain valve remains closed for a certain period of time, the DCS issues an alarm to the operators, who then notify maintenance personnel to handle the condensate line / drain valve. When the condensate in the condensate tank reaches and covers the sensing end of the upper temperature sensing element TE1 for various reasons, the temperature sensed by the upper temperature sensing element will drop rapidly. The DCS continues to issue a command to open the drain valve and simultaneously issues the highest-level alarm to the operators, who will then immediately take action.

[0027] This device uses a steam trap at the lowest point of the steam pipeline and a pneumatic steam valve in the drain line. Combined with upper and lower temperature sensing elements and a distributed control system, it indirectly detects the liquid level by utilizing temperature changes, replacing traditional level switches and reducing hardware costs. Since the temperature elements are directly inserted into the tank, heat loss from an external float is avoided, improving system economy. Simultaneously, the distributed control system enables automated control, reducing manual intervention. Its initial investment is low, and maintenance is minimal.

[0028] This device can promptly determine changes in the liquid level in the steam condensate tank of the steam condensate pipeline. It replaces expensive liquid level measuring instruments and matching measuring pipelines and valves with inexpensive temperature sensing elements, effectively monitoring changes in the liquid level of the medium in the condensate tank. During unit operation, it also eliminates heat loss caused by the external float of the liquid level measuring instrument, reducing the initial investment in the project, and effectively controls the opening and closing of the condensate valve, improving the economic efficiency of the system operation.

[0029] like Figure 2 The diagram shows the installation of the temperature sensing elements for the medium at the top and bottom of the condensate tank; the installation methods for both are exactly the same.

[0030] In one embodiment, the upper temperature sensing element 10 and the lower temperature sensing element 11 are both externally threaded armored thermocouples, and the side wall of the condensate tank 2 is provided with internally threaded mounting seats 35 and 36. The upper temperature sensing element 10 and the lower temperature sensing element 11 are installed by matching the external threads with the internally threaded mounting seats 35 and 36.

[0031] In application, both the upper temperature sensing element 10 and the lower temperature sensing element 11 are externally threaded armored thermocouples. The side wall of the condensate tank 2 is provided with internally threaded mounting seats 35 and 36. The upper temperature sensing element 10 and the lower temperature sensing element 11 are respectively matched and installed with the internally threaded mounting seats 35 and 36 through external threads to ensure the stability and sealing of the temperature sensing elements. For the externally threaded armored thermocouples, standard thread specifications can be used to achieve reliable connection. For the internally threaded mounting seats 35 and 36, stainless steel materials can be used to resist high temperature and corrosion.

[0032] This application embodiment uses an externally threaded assembled armored thermocouple matched with an internally threaded mounting base on the side wall of the condensate tank. This installation method ensures the mechanical stability and sealing of the temperature sensing element. The armored structure protects the thermocouple from high pressure and corrosive environments, extending its service life. The threaded connection facilitates installation and maintenance, reduces downtime, and ensures accurate transmission of temperature signals.

[0033] In one embodiment, the upper temperature sensing element 10 is installed at 2 / 3 of the height of the condensate tank 2, and the lower temperature sensing element 11 is installed at 1 / 3 of the height of the condensate tank 2.

[0034] In application, the upper temperature sensing element 10 is installed at 2 / 3 of the height of the condensate tank 2, and the lower temperature sensing element 11 is installed at 1 / 3 of the height of the condensate tank 2, corresponding to the set point for liquid level detection. The installation height can be determined by calculation based on the actual size of the condensate tank 2. For the temperature sensing element, a calibration tool can be used to ensure that the insertion depth meets the requirements, such as an effective insertion depth of not less than 50 mm and approximately half the inner diameter of the condensate tank (the inner diameter of the condensate tank is not less than 100 mm).

[0035] In this embodiment, the temperature sensing element is fixed at a specific height position of the condensate tank, corresponding to the liquid level control point. This allows the distributed control system to accurately determine the condensate accumulation stage. The upper element monitors for high liquid level warnings at two-thirds of the height, while the lower element triggers conventional condensation at one-third of the height. This layout optimizes the detection response, avoids misjudgment of liquid level, and improves control reliability.

[0036] A condensate tank 2 is installed at the condensate drain interface on steam pipe 1. The condensate tank 2 houses the upper temperature sensing element 10 and the lower temperature sensing element 11. Both the upper and lower temperature sensing elements 10 and 11 are installed corresponding to the internal thread mounting seats 35 and 36 (seat height is 50mm, outer radius is approximately 70mm). The threads of the temperature sensing elements and the mounting seats are matched. The temperature sensing elements are of external thread type, with an effective insertion depth considered to be approximately half the inner diameter of the condensate tank. Here, we use an outer diameter of 762mm for the steam pipe, a height of 830mm for the condensate tank 2, and an outer diameter of 219mm, a wall thickness of 8mm, and an inner diameter of 203mm for the condensate tank. The temperature sensing elements TE1 and TE2 are external thread assembled armored thermocouples with an effective insertion depth of 100mm, matched with the 50mm high internal thread mounting seats 35 and 36. The upper temperature sensing element is installed at the reserved hole at 2 / 3 of the height of the condensate tank, and the lower temperature sensing element is installed at the reserved hole at 1 / 3 of the height of the condensate tank.

[0037] In one embodiment, the drainage conduit includes: The first drainage pipe 3 is connected to the outlet of the drainage tank 2; The second drainage pipe 5 is connected at one end to the outlet of the first drainage pipe 3 and at the other end to the inlet of the pneumatic drainage valve 6. The third drainage pipe 7 is connected to the outlet of the pneumatic drainage valve 6; A drainage throttling orifice 8 is installed on the third drainage pipe 7, and its outlet is connected to the drainage expansion container interface 9.

[0038] In application, the device includes a first drain pipe 3 connected to the outlet of the drain tank 2, a second drain pipe 5 connected at one end to the outlet of the first drain pipe 3 and at the other end to the inlet of the pneumatic drain valve 6, a third drain pipe 7 connected to the outlet of the pneumatic drain valve 6, and a drain throttling orifice 8 disposed on the third drain pipe 7, with its outlet connected to the drain expansion container interface 9. Seamless steel pipes can be used for the drain pipes to ensure pressure resistance, and the drain throttling orifice 8 can be designed as a replaceable orifice plate to adjust the flow rate.

[0039] In application, during unit startup and low-load operation, the steam pipeline contains condensate due to low superheat or non-superheated steam. A condensate trap is installed at the lowest point of the steam pipeline, with a condensate tank at the interface between the condensate trap and the steam pipeline. During normal unit operation, the condensate in the steam pipeline gradually condenses into the condensate tank. The manual condensate trap is normally open when not under maintenance. The DCS system controls the pneumatic condensate trap to open, draining the condensate into the condensate expansion tank. Once the unit load reaches a certain value, the pipeline warm-up is complete, and the condensate has been completely drained, at which point the DCS controls the condensate trap to close. The pneumatic condensate trap is controlled by a solenoid valve, which opens in the event of power or air loss to ensure system safety. Regardless of the operating conditions of the unit, including when it is under a certain load or at full load, the low-temperature reheat steam pipeline with low superheat will gradually condense into the condensate tank. Temperature measuring elements for measuring the condensate inside the tank are installed at the upper and lower parts of the condensate tank. The temperature measuring elements are thermocouples (TC), and the signals from the temperature measuring elements are transmitted to the DCS.

[0040] The drainage pipeline structure of this application embodiment consists of multiple pipe sections and throttling orifices, which ensures the orderliness of the drainage process. The throttling orifices limit the flow to protect downstream equipment, and the segmented pipe design facilitates pressure management and fault isolation. This configuration enhances the overall stability of the system, simplifies the layout, and reduces the risk of pipe stress.

[0041] In one embodiment, the drainage pipeline also includes a manual drainage valve 4, which is disposed on the first drainage pipeline 3.

[0042] In application, the drainage pipeline also includes a manual drainage valve 4, which is installed on the first drainage pipeline 3 and is used to isolate the system during maintenance. The manual drainage valve 4 can be a gate valve or a ball valve to achieve reliable shut-off. As for the installation position, it can be set upstream of the pneumatic drainage valve 6 for easy operation and maintenance.

[0043] This application embodiment adds a manual drain valve to the drain line, providing a physical isolation means during maintenance. The manual valve can be operated manually in case of pneumatic valve failure, ensuring safe system operation. This redundant design improves availability and avoids system downtime due to the failure of a single valve.

[0044] In one embodiment, the signal input terminal of the distributed control system 12 is also connected to the valve status output terminal of the pneumatic steam trap 6, for receiving the fully open position signal and the fully closed position signal of the pneumatic steam trap 6.

[0045] like Figure 3 This is a control logic diagram of a hydrophobic tank level detection and hydrophobic control device provided in one embodiment of this application.

[0046] In the application, the signal input terminal of the distributed control system 12 in the device is also connected to the valve status output terminal of the pneumatic steam trap 6 to receive the fully open position signal and the fully closed position signal of the pneumatic steam trap 6 in order to realize valve status monitoring. For the valve status output terminal, limit switches or position sensors can be used to provide signals. For the distributed control system 12, a digital input module can be integrated to collect these signals for logical judgment.

[0047] The distributed control system of this application collects the status signal of the pneumatic steam trap, realizing closed-loop monitoring. The feedback of the valve's fully open and fully closed positions helps to verify the correctness of the control action and promptly detect internal leakage or jamming faults. This real-time monitoring improves the system's response accuracy and maintenance efficiency.

[0048] In one embodiment, the distributed control system 12 includes: The first comparator 25 has its input terminal connected to the temperature signal output terminal of the upper temperature sensing element 10; The second comparator 26 has its input terminal connected to the temperature signal output terminal of the lower temperature sensing element 11; The logic OR circuit 27 has its first input terminal connected to the output terminal of the first comparator 25 and its second input terminal connected to the output terminal of the second comparator 26. The monostable multivibrator 30 has its reset terminal connected to the output terminal of the logic OR circuit 27 via the logic pulse module 28, its set terminal connected to the output terminal of the logic OR circuit 27 via the first logic delay module 29, and its output terminal connected to the control terminal of the pneumatic steam trap 6.

[0049] In the application, the distributed control system 12 in the device includes a first comparator 25, whose input is connected to the temperature signal output of the upper temperature sensing element 10; a second comparator 26, whose input is connected to the temperature signal output of the lower temperature sensing element 11; a logic OR circuit 27, whose first input is connected to the output of the first comparator 25 and whose second input is connected to the output of the second comparator 26; a monostable multivibrator 30, whose reset terminal is connected to the output of the logic OR circuit 27 via a logic pulse module 28, whose set terminal is connected to the output of the logic OR circuit 27 via a first logic delay module 29, and whose output is connected to the control terminal of the pneumatic steam trap 6. For the first comparator 25 and the second comparator 26, an analog comparator integrated circuit can be used to implement temperature threshold comparison. For the first logic delay module 29, an adjustable time constant, such as 15 seconds, can be set to optimize the control timing.

[0050] In applications, the logic pulse module 28 can employ a pulse generation module based on an RC differentiator circuit, with an RC differentiator circuit consisting of a resistor R and a capacitor C as its core. Furthermore, to shape and amplify the generated pulse, a Schmitt trigger (such as the 74HC14 chip) or a simple transistor amplifier circuit is typically connected subsequently. Its input is connected to the output of the logic OR circuit 27. The input signal first enters the RC differentiator circuit. When the input signal undergoes a transition (e.g., from 0V to 5V), a spike pulse (positive pulse) is instantaneously generated across the resistor R because the voltage across the capacitor C cannot change abruptly. Subsequently, the capacitor C charges rapidly, and the voltage across the resistor R decays quickly to zero. When the input signal transitions from a high level back to a low level, the capacitor discharges, generating a negative spike pulse. The generated spike pulse may have an imperfect waveform and its amplitude may be attenuated. By connecting it to a Schmitt trigger NOT gate for shaping, a clean, steep square wave pulse can be obtained. Through circuit design (e.g., selecting the values ​​of R and C), the width of the output pulse can be precisely controlled. The RC differentiator circuit and Schmitt trigger can be fabricated on a dedicated printed circuit board (PCB) of the DCS system and electrically connected to other modules (logic OR circuit 27, monostable multivibrator 30) through copper foil traces on the PCB.

[0051] In the application, the first logic delay module 29 can be implemented using a timer module based on an RC charging and discharging circuit. This module can be a delay circuit with a 555 timer chip as its core. Its structure includes: a 555 timer IC, a resistor R, a capacitor C, a diode, and necessary connection pins. The output signal of the logic OR circuit 27 is used as a trigger signal and input to the TRIG pin of the 555 timer. The values ​​of the resistor R and the capacitor C together determine the charging time constant of the RC circuit, i.e., the delay time (T=1.1RC). By selecting specific resistance and capacitance values ​​for R and C, the delay can be set to 15 seconds. When the trigger signal arrives, the OUTPUT pin of the 555 timer will immediately output a high level (or a low level) and start timing. After the predetermined time of 15 seconds, the level state of the OUTPUT pin flips. This flipped signal is used as the delayed output signal and sent to the set terminal S of the monostable multivibrator 30, thereby generating a command to close the valve. The 555 timer circuit can be fabricated as an independent printed circuit board (PCB). This PCB can be electrically connected and exchange signals with other logic boards (such as comparator boards, logic OR boards) on the DCS system backplane through standard pins or terminals.

[0052] In applications, the first logic delay module 29 can also be a hardware delay module based on a digital counter. This module can be a digital delay circuit consisting of a crystal oscillator, a frequency divider, and a counter chip (such as CD4060). The crystal oscillator provides stable clock pulses. The frequency divider and the counter chip count the clock pulses. The output signal of the logic OR circuit 27 is used to reset or start the counter. The counter starts counting from zero, and when the count value reaches a preset value corresponding to 15 seconds, the level of a certain output pin of the counter changes, generating a delay end signal. The preset value can be set by a hardware DIP switch or by connecting to a fixed count output terminal. This counter circuit also exists in the form of a dedicated PCB and is connected to other hardware modules in the system via a backplane bus or cable.

[0053] The distributed control system of this application integrates a comparator, logic circuit and monostable trigger to form a rigorous control sequence. The temperature signal is compared and then triggered to activate the valve through logic OR. The delay module ensures the integrity of the hydrophobic barrier. This logic design optimizes the control timing, reduces unnecessary valve operations and lowers energy consumption.

[0054] In one embodiment, the distributed control system 12 further includes: The second logic delay module 32 has its input connected to the output of the second comparator 26; The first alarm signal output terminal 33 is connected to the output terminal of the second logic delay module 32; The second alarm signal output terminal 34 is connected to the output terminal of the first comparator 25.

[0055] In the application, the distributed control system 12 in the device also includes a second logic delay module 32, whose input terminal is connected to the output terminal of the second comparator 26, the first alarm signal output terminal 33 is connected to the output terminal of the second logic delay module 32, and the second alarm signal output terminal 34 is connected to the output terminal of the first comparator 25, for generating different alarm signals.

[0056] In the application, the second logic delay module 32 can be a delay module based on a retriggerable monostable multivibrator (TSM), specifically a circuit using a TSM chip (such as 74HC123). The temperature drop signal output by the second comparator 26 is connected to the trigger input of the 74HC123. The resistors and capacitors (Rext, Cext) around the chip determine the monostable period (i.e., the delay time, for example, 8 seconds). As long as the trigger signal remains valid within the 8-second delay period (i.e., the temperature remains low), the output will remain transient (e.g., high level). Once the 8-second period ends and the trigger signal still exists, the output will transition back to the steady state (e.g., low level), and this transition edge can be used as an "unobstructed drainage" alarm signal output. The characteristic of this circuit is that if the trigger signal disappears within 8 seconds (indicating that the liquid level has been discharged normally), the output will reset prematurely, preventing false alarms. This circuit serves as a functional board within the DCS system. It receives signals from the comparator through the input / output interface on the board and sends signals to the alarm indication unit (such as an alarm light or relay).

[0057] In applications, the second logic delay module 32 can also use a hardware logic unit based on a small programmable logic device (such as a CPLD), specifically a small CPLD chip (such as Altera's MAX series or Xilinx's CoolRunner series).

[0058] This application embodiment extends the alarm function by implementing tiered early warning through a delay module and an alarm output terminal. An alarm is triggered when the temperature abnormality persists, enabling operators to intervene quickly and prevent system risks caused by poor drainage. This early warning mechanism enhances fault prevention capabilities.

[0059] like Figure 3 As shown, the working principle of this device is as follows: The DCS system continuously receives the upper temperature signal 21 from the upper temperature sensing element 10 of the steam trap, the lower temperature signal 22 from the lower temperature sensing element 11 of the steam trap, and the fully open position signal 23 and fully closed position signal 24 from the pneumatic steam trap 6. The upper temperature signal 21 from the upper temperature sensing element TE1 of the steam trap is compared by the first comparator 25 (temperature drop logic comparator), and the lower temperature signal 22 from the lower temperature sensing element TE2 of the steam trap is compared by the second comparator 26 (temperature drop logic comparator). After a logical OR operation is performed by the logic OR circuit 27, the signal is sent to the reset terminal R of the monostable multivibrator 30 through the logic pulse module 28. At this time, the set terminal S of the monostable multivibrator 30 generates a low-level signal 31 to the single-coil solenoid valve control circuit of the pneumatic steam trap, causing the solenoid valve to lose power and cut off the power supply to the pneumatic steam trap. After the valve loses power, it is opened by the action of the spring. After the output signal of the logic OR circuit 27 is delayed by the first logic delay module 29 (which can be set to 15s to ensure that the liquid in the condensate tank is completely drained and that as little steam as possible is carried away to maintain the economic efficiency of the system operation), it is sent to the set terminal S of the monostable trigger 30. This is to close the condensate valve after one drainage is completed, so as to ensure the safety and economy of the system operation.

[0060] The lower temperature signal 22 of the temperature sensing element TE2 at the bottom of the condensate tank is delayed by the second comparator 26 and then by the second logic delay module 32 (the delay time can be 8s, taking into account the time delay of the valve to a certain opening degree and the temperature sensing element sensing temperature). This generates a "drainage obstruction" alarm signal, which is output through the first alarm signal output terminal 33.

[0061] The upper temperature signal 21 of the temperature measuring element TE1 at the top of the condensate tank is directly generated by the first comparator 25 to produce the highest level "condensate blockage exceeding the warning level" alarm signal, which is then output through the second alarm signal output terminal 34.

[0062] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A device for detecting and controlling the liquid level in a hydrophobic tank, characterized in that, include: Steam pipeline (1), with a condensate tank (2) provided at the lowest point of the steam pipeline (1); A drainage pipeline is connected between the drainage tank (2) and the drainage expansion container interface (9), and the drainage pipeline is equipped with a pneumatic drainage valve (6). The temperature detection assembly includes an upper temperature sensing element (10) and a lower temperature sensing element (11). The upper temperature sensing element (10) is disposed on the upper part of the hydrophobic tank (2), and the lower temperature sensing element (11) is disposed on the lower part of the hydrophobic tank (2). The distributed control system (12) has its signal input terminal electrically connected to the signal output terminals of the upper temperature measuring element (10) and the lower temperature measuring element (11) for receiving temperature signals. The control signal output terminal of the distributed control system (12) is connected to the control terminal of the pneumatic steam trap (6).

2. The hydrophobic tank level detection and hydrophobic control device as described in claim 1, characterized in that, The upper temperature measuring element (10) and the lower temperature measuring element (11) are both externally threaded armored thermocouples. The side wall of the condensate tank (2) is provided with an internally threaded mounting seat (35, 36). The upper temperature measuring element (10) and the lower temperature measuring element (11) are matched and installed with the internally threaded mounting seat (35, 36) through external threads.

3. The hydrophobic tank level detection and hydrophobic control device as described in claim 1 or 2, characterized in that, The upper temperature measuring element (10) is installed at 2 / 3 of the height of the condensate tank (2), and the lower temperature measuring element (11) is installed at 1 / 3 of the height of the condensate tank (2).

4. The hydrophobic tank level detection and hydrophobic control device as described in claim 1, characterized in that, The drainage pipeline includes: The first drainage pipe (3) is connected to the outlet of the drainage tank (2); The second drainage pipe (5) is connected at one end to the outlet of the first drainage pipe (3) and at the other end to the inlet of the pneumatic drainage valve (6); The third drainage pipe (7) is connected to the outlet of the pneumatic drainage valve (6); A condensate drain hole (8) is provided on the third condensate drain pipe (7), and its outlet is connected to the condensate expander port (9).

5. The hydrophobic tank level detection and hydrophobic control device as described in claim 4, characterized in that, The drainage pipeline also includes a manual drainage valve (4), which is installed on the first drainage pipeline (3).

6. The hydrophobic tank level detection and hydrophobic control device as described in claim 1, characterized in that, The signal input terminal of the distributed control system (12) is also connected to the valve status output terminal of the pneumatic steam trap (6) to receive the fully open position signal and the fully closed position signal of the pneumatic steam trap (6).

7. The hydrophobic tank level detection and hydrophobic control device as described in claim 1 or 6, characterized in that, The distributed control system (12) includes: The first comparator (25) has its input terminal connected to the temperature signal output terminal of the upper temperature measuring element (10); The second comparator (26) has its input terminal connected to the temperature signal output terminal of the lower temperature sensing element (11); A logic OR circuit (27) has its first input terminal connected to the output terminal of the first comparator (25) and its second input terminal connected to the output terminal of the second comparator (26); The reset terminal of the monostable multivibrator (30) is connected to the output terminal of the logic OR circuit (27) through the logic pulse module (28), the set terminal is connected to the output terminal of the logic OR circuit (27) through the first logic delay module (29), and the output terminal is connected to the control terminal of the pneumatic steam trap (6).

8. The hydrophobic tank level detection and hydrophobic control device as described in claim 7, characterized in that, The distributed control system (12) further includes: The second logic delay module (32) has its input connected to the output of the second comparator (26); The first alarm signal output terminal (33) is connected to the output terminal of the second logic delay module (32); The second alarm signal output terminal (34) is connected to the output terminal of the first comparator (25).

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