Automatic anti-condensation purge system and method for ultrasonic or radar level gauge

Abstract

This invention discloses an automatic anti-condensation purging system and method for ultrasonic / radar level gauges. The system includes an anti-vapor protection device and an automatic purging control air supply unit. The protection device is a double-sleeve structure fitted over the probe, forming an annular air duct, with a directional injection hole at its lower end. The control unit includes a solenoid valve and a pressure reducing valve controlled by a time relay. The method involves setting the purging cycle and duration, and the time relay periodically triggering the solenoid valve to open, allowing dry compressed air to be ejected at high speed through the injection hole in the annular air duct, directionally purging the antenna surface. After purging, the valve is closed, and the process is repeated. Preferably, an electric heating and temperature control system is installed inside the annular air duct. This invention achieves timed, directional, uniform, and low-energy purging of the level gauge antenna surface, effectively preventing water vapor condensation and dust adhesion, and significantly improving the measurement accuracy and operational reliability of the instrument in harsh environments.

Description

Technical Field

[0001] This invention relates to the field of industrial testing technology, specifically to an automatic anti-condensation purging system and method for ultrasonic or radar level gauges, applicable to level measurement in high-temperature and high-humidity conditions such as slurry tanks and pits in wet desulfurization systems of power plants. Background Technology

[0002] In limestone-gypsum wet desulfurization systems in power plants, level measurement in containers such as slurry tanks and pits is crucial, as its accuracy directly affects the stability and safety of the system's interlocking control. Currently, radar level gauges or ultrasonic level gauges are commonly used for measurement due to their advantages such as non-contact operation, high accuracy, and convenient installation and maintenance.

[0003] However, in actual operation, the temperature of the desulfurization slurry is usually maintained at around 40℃. When the ambient temperature (especially in winter) is low, a large amount of water vapor generated by evaporation inside the container will condense into droplets or water films on the surface of the colder level gauge probe's transmitting antenna. These condensates can severely interfere with the transmission and reception of radar waves, or absorb and scatter ultrasonic energy, leading to attenuation, distortion, or even complete failure of the level gauge's measurement signal. This fault will cause abnormal level display, which in turn will cause related interlocking protection to malfunction, seriously affecting the safe and stable operation of the desulfurization system. In existing technologies, manual periodic wiping is usually used for this purpose, but this method has problems such as low efficiency, high risk, and unsustainable effect.

[0004] Traditional approach: After condensation occurs, manual intervention (wiping) or external heating is applied. This increases maintenance workload and can also affect the wear and tear of electronic components and increase system energy consumption. Invention approach: Creatively adopts a proactive maintenance mechanism of "periodic, short-term, directional air blowing." Its core mechanism is not to continuously fight against the overall environment, but to precisely establish a brief, dry microenvironment at the critical location of the antenna surface, forcibly breaking the condensation conditions and nipping the problem in the bud. This "precise intervention, on-demand activation" mechanism achieves high efficiency and energy saving while ensuring effectiveness.

[0005] This invention aims to overcome the shortcomings of the prior art and provide an automatic anti-condensation purging system and method for ultrasonic / radar level gauges. This system can purge the antenna surface in a timed, directional, and uniform manner, and can be combined with temperature control to prevent condensation, effectively removing deposits and ensuring long-term stable and accurate operation of the level gauge, while also achieving energy saving and consumption reduction. Summary of the Invention

[0006] The purpose of this invention is to address the above-mentioned problems by providing an automatic anti-condensation purging system and method for ultrasonic or radar level gauges.

[0007] The objective of this invention is achieved as follows: An automatic anti-condensation purging system for ultrasonic or radar level gauges, comprising: an anti-vapor protection device and an automatic purging control air supply unit; the anti-vapor protection device includes a double-sleeve structure coaxially sleeved outside the level gauge probe, the double-sleeve structure being detachably connected to the level gauge body; an annular air duct is formed between the inner and outer sleeves of the double-sleeve structure; at the lower end of the annular air duct, near the level gauge transmitting antenna, 10-15 injection holes, i.e., purging air holes, are evenly distributed along the circumference; a compressed air inlet is provided on the outer wall of the double-sleeve structure, the compressed air inlet being connected to the annular air duct; the automatic purging control air supply unit is used to provide compressed air and is connected to the compressed air inlet via a pipeline; the unit includes, in sequence along the airflow direction: an air source shut-off valve, a pressure reducing valve, a solenoid valve, and a time relay controller; the time relay controller is electrically connected to the solenoid valve and is used to set and control the opening and closing cycle and single opening duration of the solenoid valve.

[0008] The inner wall of the annular air duct is equipped with an electric heating tape. A temperature measuring point is located inside the annular air duct, above the injection hole. The temperature measuring point is connected to a temperature controller. The temperature controller controls the start and stop of the electric heating tape based on the feedback signal from the temperature measuring point. The start and stop of the electric heating tape is automatic based on the feedback from the temperature measuring point. The temperature control range is 20-30℃. When the temperature is below 20℃, the heating power is turned on; when the temperature is above 30℃, the heating power is turned off.

[0009] The axis of the injection hole is set at an angle of 10-60° to the axis of the level gauge probe, so that the blown airflow is directed toward the antenna surface.

[0010] The double-sleeve structure is made of corrosion-resistant material, namely polytetrafluoroethylene. The height of the sleeve is 8-13cm. The distance between the liquid level gauge emission source and the bottom of the sleeve is required to be 5-8cm, and the horizontal distance of the annular air duct is 1-2cm.

[0011] The time relay controller is programmable and is used to adjust the purging cycle and the duration of a single purging according to environmental parameters.

[0012] The automatic anti-condensation purging method of the system is characterized by the following steps: Step 1: System initialization, setting the purging cycle T and single purging duration t of the time relay; Step 2: The time relay starts timing, and when the preset purging cycle T is reached, it sends an opening signal to the solenoid valve; Step 3: The solenoid valve opens, and compressed air, after being pressurized to 0.1-0.15MPa by the pressure reducing valve, enters the annular air duct and is ejected from the injection hole to purge the surface of the level gauge transmitting antenna; Step 4: After the purging continues for the preset duration t, the time relay sends a closing signal to the solenoid valve, and the purging stops; Step 5: The time relay resets and restarts timing to enter the next purging cycle.

[0013] During the timing wait period in step two, a temperature control sub-step is also included: monitoring the temperature inside the annular duct and controlling the start and stop of the electric heating tape through a temperature controller. The temperature control range is 20-30℃. When the temperature is below 20℃, the heating power supply is turned on, and when the temperature is above 30℃, the heating power supply is turned off, so as to maintain the temperature inside the duct above the ambient dew point temperature.

[0014] The beneficial effects of this invention are: 1. High-efficiency directional cleaning: The double-sleeve structure forms an annular air duct, which, together with the injection holes at a specific angle, can concentrate and uniformly guide compressed air to the antenna surface, and can form a rotating sweeping effect, resulting in high cleaning efficiency and low air consumption.

[0015] 2. Intelligent anti-condensation: The integrated electric heating and temperature control system can actively maintain the temperature of the annular air duct and surrounding area above the dew point, fundamentally preventing water vapor condensation, and is especially suitable for low temperature and high humidity environments.

[0016] 3. Automatic energy-saving operation: It adopts programmable time relay control to realize timed and intermittent purging, avoiding the huge energy consumption of traditional continuous purging. Users can flexibly adjust the strategy according to the working conditions, which has a high degree of intelligence.

[0017] 4. Reliable structure and easy maintenance: The protective device is made of corrosion-resistant materials and is detachably connected to the level gauge body. The structure is simple and compact, does not affect the original performance of the instrument, and is easy to install, inspect and maintain.

[0018] 5. Wide applicability: This system and method can be adapted to various models of ultrasonic and radar level gauges and can be widely used in various industrial measurement scenarios where there is a risk of condensation, frost, and dust pollution. Attached Figure Description

[0019] The present invention will now be further described with reference to the accompanying drawings.

[0020] Figure 1 This is a schematic diagram of an automatic control structure for compressed air.

[0021] Figure 2This is a schematic diagram of a water vapor protection device.

[0022] Figure 3 This is a top view of the water vapor protection device.

[0023] Figure 4 This is a circuit diagram for a water vapor protection device.

[0024] 1. Air source valve, 2. Pressure reducing valve, 3. Solenoid valve, 4. Time relay, 5. Liquid level gauge, 6. Water vapor protection cover, 7. Outer wall of annular sleeve, 8. Inner wall of annular sleeve, 9. Purge air hole, 10. Electric heating tape, 11. Liquid level gauge probe, 12. Compressed air interface, 13. Temperature controller interface, 14. Electric heating power cord interface, 15. Temperature probe, 16. Temperature controller, 17. Compressed air pipeline network, 18. Slurry tank. Detailed Implementation

[0025] The "double-sleeve annular air duct + bottom oblique injection" structure of this invention is key to achieving uniform and effective purging. The double sleeves form a sealed, guided annular air duct, ensuring uniform distribution of air pressure and flow. The oblique injection hole design at the bottom allows the airflow to cover the antenna surface at a certain angle, forming an effect similar to an "air curtain" or "swirl sweep," eliminating dead zones. This is far more effective and uniform than single-point direct blowing or external heating band wrapping.

[0026] Intelligent integration of "timed control + adjustable parameters": This combines simple industrial components (solenoid valves, time relays) with the protection requirements of level gauges, forming a low-cost, highly reliable automated control unit. The programmable time relays give the system high flexibility, enabling it to automatically adjust maintenance strategies according to different seasons and diurnal temperature differences, demonstrating the prototype of intelligent maintenance.

[0027] Optional "Hot Air Enhancement" module: This module adds an air heating device to the basic air blowing, upgrading the solution to "hot air drying and purging". This is not just an increase in quantity, but a qualitative improvement, advancing from "blowing away liquid water" to "preventing water vapor condensation", greatly expanding the applicable temperature and humidity range of the solution and making it more capable of handling extreme working conditions.

[0028] Non-invasive retrofitting with strong compatibility: The protective device is externally mounted, requiring no structural modifications to the existing level gauge or the drilling of new holes in the container. Utilizing readily available instrument air sources within the factory, it achieves "plug and play, rapid deployment," significantly reducing the barriers to entry and costs associated with retrofitting.

[0029] Replacing repair with maintenance improves reliability: What were originally unexpected failures requiring repair are transformed into predictable and plannable preventative maintenance. Through automated, short-cycle maintenance, major operational risks such as system cascading trips caused by sudden level gauge inaccuracies are avoided, controlling potential problems at the outset.

[0030] Combining universality and specialization: Although the system is designed for desulfurization systems, its principle of solving the problem of "high-temperature and high-humidity gases condensing upon cooling and affecting instruments" makes it equally applicable to many industries with similar working conditions, such as chemical, papermaking, and wastewater treatment, and has broad application prospects and promotional value.

[0031] This invention provides a highly practical and systematic solution for engineering applications. It precisely addresses a long-standing pain point in industrial measurement and solves it in a simple, ingenious, efficient, and low-cost manner.

[0032] Effects: 1. High degree of automation and long-lasting stable effect: Automatic control via time relay enables unattended timed purging, effectively preventing moisture condensation on the antenna surface and fundamentally solving the measurement inaccuracy problem. 2. Simple structure and easy modification: The anti-vapor protection device can be directly installed on existing level gauges without modifying the level gauge body or container structure. Utilizing existing instrument air sources in the factory, implementation costs are low and it is easy to promote. 3. Strong adaptability and flexible adjustment: The purging cycle and duration can be flexibly set according to season, weather, medium temperature, and other operating conditions, optimizing compressed air consumption while ensuring effectiveness. 4. Improved system reliability: Significantly reduces system malfunctions and unplanned shutdowns caused by level gauge condensation failures, ensuring the long-term stable operation of main process systems (such as desulfurization systems). 5. Significantly reduced maintenance costs: Essentially eliminates the risks of manual wiping at heights and the workload of frequent maintenance, reducing the overall equipment maintenance cost.

[0033] The present invention adopts the following technical solution: an automatic anti-condensation purging system for ultrasonic / radar level gauges, comprising: an anti-water vapor protection device and an automatic purging control air supply unit.

[0034] The moisture-proof protection device includes a double-sleeve structure coaxially sleeved outside the level gauge probe. This double-sleeve structure is detachably connected to the level gauge body via threads or a flange. An annular air duct is formed between the inner and outer sleeves of the double-sleeve structure. At the lower end of the annular air duct, near the level gauge's transmitting antenna, several injection holes are evenly distributed circumferentially. A compressed air inlet is located on the outer wall of the double-sleeve structure, communicating with the annular air duct. The level gauge and the moisture-proof cover are connected by threads, and the level gauge and the top cover of the slurry tank are connected by a flange.

[0035] The automatic purging control air supply unit is used to provide clean and dry compressed air and is connected to the air inlet through a pipeline. The unit includes, in sequence along the airflow direction: an air source shut-off valve, a solenoid valve, a pressure reducing valve, and a time relay controller. The time relay controller is electrically connected to the solenoid valve and is used to set and control the opening and closing cycle and single opening duration of the solenoid valve.

[0036] Furthermore, an electric heating tape is wrapped around the inner wall of the annular duct, and a temperature measuring point is also provided inside the annular duct. The temperature measuring point is connected to a temperature controller, which controls the start and stop of the electric heating tape based on the feedback signal from the temperature measuring point. The interface of the electric heating power cord in the figure refers to the perforation location of the power cord.

[0037] Furthermore, the axial direction of the injection hole forms an angle of 10° to 60° with the axis of the level gauge probe, so that the airflow blown out of the injection hole is directed toward the antenna surface and forms a swirling effect.

[0038] Furthermore, the double-sleeve structure is made of corrosion-resistant material, preferably polytetrafluoroethylene, with a sleeve height of 10cm and a horizontal distance of 1-2cm between the sleeves and the annular air duct.

[0039] Furthermore, the time relay controller is programmable and is used to adjust the purging cycle and the duration of each purging according to environmental parameters, allowing users to adjust the purging cycle and the duration of each purging according to environmental temperature and humidity parameters.

[0040] An automatic anti-condensation purging method based on the above system includes the following steps: S1: System initialization, setting the purging cycle T and single purging duration t of the time relay according to the site environment; S2: The time relay starts timing, and when the accumulated time reaches the preset purging cycle T, the time relay sends an opening signal to the solenoid valve; S3: The solenoid valve opens, and compressed air, after being pressurized by the pressure reducing valve, enters the annular duct of the anti-vapor protection device through the pipeline, and is finally ejected at high speed from the injection hole to uniformly purge the surface of the level gauge transmitting antenna; S4: After the purging continues for the preset duration t, the time relay sends a closing signal to the solenoid valve, the solenoid valve closes, and the purging stops; S5: The time relay resets and restarts timing, entering the next purging cycle. During the timing wait period in step S2, a temperature control sub-step is also included: monitoring the temperature inside the annular duct and controlling the start and stop of the electric heating tape through a temperature controller to maintain the temperature inside the duct above the ambient dew point temperature. Example 1

[0041] Take the ultrasonic level gauge of the gypsum slurry tank in the desulfurization system of a power plant as an example.

[0042] like Figure 1 and Figure 2 As shown, the automatic anti-condensation purging system provided by the present invention mainly consists of two parts: an anti-vapor protection device installed at the bottom of the level gauge and an independent automatic purging control air supply unit.

[0043] The core of the moisture-resistant protective device is a double-sleeve structure 6 made of polytetrafluoroethylene (PTFE). This structure is connected to the level gauge body 5 via threads or flanges for sealing. An annular, sealed air duct is formed between the inner sleeve 8 and the outer sleeve 7. At the lowest point of this annular air duct, closest to the level gauge probe (transmitting antenna), a ring of evenly distributed tiny purge holes 9 is machined, with the axis of each hole inclined downwards at approximately a 30° angle to the axis of the probe 11. A compressed air inlet 12 is installed on the side wall of the double-sleeve structure 8, communicating with the annular air duct. An electric heating tape 10 is tightly wrapped around the inner wall of the annular air duct, and a PT100 temperature sensor is installed inside the duct as a temperature measuring point 15. The temperature measuring point 15 is connected to a temperature controller 14 installed in the instrument box, forming a closed-loop temperature control system to prevent condensation caused by excessively low temperatures due to the introduction of cold air into the air duct.

[0044] The automatic purging control air supply unit is connected to the air inlet 12 via an air supply pipeline. Air drawn from the factory's compressed air network first passes through the air supply shut-off valve 1 (normally open, used to cut off the air supply during maintenance), then sequentially flows through the pressure reducing valve 2 and the normally closed two-position two-way solenoid valve 3. The pressure reducing valve 2 stabilizes the air pressure at a suitable purging pressure (e.g., 0.1 MPa). The opening and closing of the solenoid valve 3 is controlled by a programmable time relay controller 4. Users can set the purging cycle (e.g., T = 10-60 minutes) and the duration of a single purging cycle (e.g., t = 10-30 seconds) on the panel of the time relay controller 4, based on the humidity and dust concentration of the ambient environment.

[0045] Its working process is as follows: 1. Initialization: Set parameters, such as T=30 minutes, t=15 seconds.

[0046] 2. Waiting and Timing: After the system is powered on, the time relay starts timing. During this waiting period, the temperature controller 14 continuously monitors the temperature inside the annular duct. If the temperature is lower than the preset anti-condensation temperature (e.g., 5°C higher than the ambient dew point temperature), the electric heating tape 10 is activated; heating stops once the temperature is reached.

[0047] 3. Triggering purging: When the timer reaches 30 minutes, the time relay outputs a switching signal to drive solenoid valve 3 to open.

[0048] 4. Purge Operation: Pressure-regulated dry compressed air rapidly enters the annular air duct and is ejected at high speed from a ring of inclined jet holes 9. This airflow impacts the surface and surrounding area of ​​the level gauge probe antenna 11 at a certain angle, not only blowing away attached dust and water droplets, but also creating a rotating sweeping effect with its tangential component, resulting in a more uniform and thorough cleaning. The purging process lasts 15 seconds.

[0049] 5. Stop and Cycle: After 15 seconds, the time relay cuts off the signal, solenoid valve 3 closes, and purging stops. The time relay resets and immediately begins a new 30-minute countdown, and the system enters a sleep waiting period, thus repeating the cycle.

[0050] This invention achieves optimal protection for the surface of the level gauge antenna with minimal energy consumption through a combination of "intermittent timed purging + active electric heat tracing and insulation," significantly improving the instrument's adaptability to harsh environments and the long-term reliability of measurement data.

[0051] The above description is only a specific embodiment of the present invention, but the structural features protected by the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. An automatic anti-condensation purging system for ultrasonic or radar level gauges, characterized in that: include: The device includes a water vapor protection device and an automatic purging control air supply unit. The water vapor protection device includes a double-sleeve structure coaxially sleeved outside the level gauge probe rod, which is detachably connected to the level gauge body. An annular air duct is formed between the inner and outer sleeves of the double-sleeve structure. At the lower end of the annular air duct, near the level gauge transmitting antenna, 10-15 injection holes, i.e., purging air holes, are evenly opened along the circumference. A compressed air inlet is provided on the outer wall of the double-sleeve structure, and the compressed air inlet is connected to the annular air duct. The automatic purging control air supply unit is used to provide compressed air and is connected to the compressed air inlet port through a pipeline; the unit includes, in sequence along the airflow direction: an air source shut-off valve, a pressure reducing valve, a solenoid valve, and a time relay controller; the time relay controller is electrically connected to the solenoid valve and is used to set and control the opening and closing cycle and single opening duration of the solenoid valve.

2. An automatic anti-condensation purging system for ultrasonic or radar level gauges according to claim 1, characterized in that: The inner wall of the annular air duct is equipped with an electric heating tape. A temperature measuring point is located inside the annular air duct, above the injection hole. The temperature measuring point is connected to a temperature controller. The temperature controller controls the start and stop of the electric heating tape based on the feedback signal from the temperature measuring point. The start and stop of the electric heating tape is automatic based on the feedback from the temperature measuring point. The temperature control range is 20-30℃. When the temperature is below 20℃, the heating power is turned on; when the temperature is above 30℃, the heating power is turned off.

3. An automatic anti-condensation purging system for ultrasonic or radar level gauges according to claim 1, characterized in that: The axis of the injection hole is set at an angle of 10-60° to the axis of the level gauge probe, so that the blown airflow is directed toward the antenna surface.

4. An automatic anti-condensation purging system for ultrasonic or radar level gauges according to claim 1, characterized in that: The double-sleeve structure is made of corrosion-resistant material, namely polytetrafluoroethylene. The height of the sleeve is 8-13cm. The distance between the liquid level gauge emission source and the bottom of the sleeve is required to be 5-8cm, and the horizontal distance of the annular air duct is 1-2cm.

5. An automatic anti-condensation purging system for ultrasonic or radar level gauges according to claim 1, characterized in that: The time relay controller is programmable and is used to adjust the purging cycle and the duration of a single purging according to environmental parameters.

6. An automatic anti-condensation purging method based on the system according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: System initialization, setting the purge cycle T and single purge duration t of the time relay; Step 2: The time relay starts timing, and when the preset purging cycle T is reached, it sends an opening signal to the solenoid valve; Step 3: The solenoid valve is opened, and the compressed air is regulated to 0.1-0.15MPa by the pressure reducing valve and then enters the annular air duct. It is then sprayed out from the injection hole to purge the surface of the level gauge transmitting antenna. Step 4: After the purging continues for the preset duration t, the time relay sends a closing signal to the solenoid valve, and the purging stops; Step 5: The time relay is reset and the timing restarts to begin the next purge cycle.

7. The automatic anti-condensation purging method according to claim 6, characterized in that: During the timing wait period in step two, a temperature control sub-step is also included: monitoring the temperature inside the annular duct and controlling the start and stop of the electric heating tape through a temperature controller. The temperature control range is 20-30℃. When the temperature is below 20℃, the heating power supply is turned on, and when the temperature is above 30℃, the heating power supply is turned off, so as to maintain the temperature inside the duct above the ambient dew point temperature.

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