Full load visualizing air leakage control system and full enclosed static seal

Abstract

The application belongs to the field of air leakage control system, and particularly relates to a full-load visual air leakage control system and a full-closed static seal, wherein the control system comprises a signal acquisition system, a fan-shaped plate lifting device and a control system; the signal acquisition system comprises an aperture lens, a support, a front-end illuminating lamp and an industrial camera, video signals are transmitted from the industrial camera to a DCS or to an on-site image display control system for image processing and output of control signals; the fan-shaped plate lifting device comprises a speed reducer, a driving disc, a spiral elevator and two hangers, and the speed reducer is controlled to be reversely rotated through the driving disc; the full-closed static seal comprises a fan-shaped plate and a static seal installed around the fan-shaped plate; the aperture lens can adapt to the harsh environment of high temperature and dust of the air preheater, the equipment is easy to maintain, the maintenance amount is low, and the effectiveness and long-term stable investment of the system air leakage rate control are ensured.

Description

Technical Field

[0001] This invention relates to the field of air leakage control system technology, and in particular to a full-load visual air leakage control system and a fully enclosed static seal. Background Technology

[0002] During hot operation of the air preheater, the uneven temperature distribution within the rotor (higher temperature at the top, lower temperature at the bottom) causes mushroom-shaped deformation, resulting in increased gaps in some areas (e.g., the outer side of the hot end) and decreased gaps in others (e.g., the outer side of the cold end). Based on the rotor deformation characteristics, the axial, bypass, and radial sealing gaps at the cold end can be pre-calculated to account for the deformation differences between the rotor and the preheater shell. During full-load operation, these gaps are effectively reduced, achieving a self-sealing effect. However, the radial gap at the hot end increases with the unit load and cannot be compensated for by fixed seals. In 1000MW units, this gap can reach 50mm, accounting for almost half of all preheater leakage. Current leakage control systems include eddy current ranging, laser ranging, and temperature tracking. Eddy current sensors can statically and dynamically measure the distance between the measured metal conductor and the probe surface non-contactly, with high linearity and high resolution. It is a non-contact, linearized metering tool. Eddy current sensors accurately measure the static and dynamic relative displacement changes between the measured object (which must be a metallic conductor) and the probe end face. In the condition analysis, vibration research, and analytical measurement of high-speed rotating machinery and reciprocating motion machinery, they can continuously and accurately acquire various parameters of rotor vibration, such as radial vibration, amplitude, and axial position, for non-contact, high-precision vibration and displacement signals. Eddy current sensors are widely used in online monitoring and fault diagnosis of large rotating machinery due to their advantages of high long-term reliability, wide measurement range, high sensitivity, and high resolution. Laser rangefinders: A laser diode emits a laser pulse towards the target. After reflection from the target, the laser light scatters in all directions. Some of the scattered light returns to the sensor receiver, is received by the optical system, and imaged onto an avalanche photodiode. An avalanche photodiode is an optical sensor with internal amplification, thus it can detect extremely weak light signals. By recording and processing the time elapsed from the emission of the light pulse to its return and reception, the target distance can be determined. Temperature tracking calculates the rotor deformation based on temperature variations, thus calculating the distance between the rotor and the sector plates.

[0003] Generally, imported eddy current sensors have a maximum operating temperature of no more than 180℃, while domestically produced ones can only reach 120℃. Furthermore, these figures are sourced from the manufacturers themselves, making them highly unreliable. According to various analyses, in reality, when the operating temperature exceeds 70℃, the sensitivity of eddy current sensors decreases significantly, and may even damage the sensor. The sensitivity of eddy current sensors is affected by temperature; as temperature increases, sensitivity decreases. The air preheater operates at a temperature of 420℃. At such temperatures, using eddy current sensors for distance measurement results in large errors. During normal operation, the air preheater contains high temperatures, dust, and corrosive gases. Laser ranging first involves a laser diode aiming at the target and emitting a laser pulse. After reflection from the target, the laser light scatters in all directions. Some of the scattered light returns to the sensor receiver. Due to interference from dust and smoke, the sensor receiver often fails to receive the reflected light, leading to large errors. Temperature tracking calculates the rotor deformation based on temperature variations, determining the distance between the rotor and the sector plates. This calculated value is theoretical and has errors compared to actual values.

[0004] Currently, air leakage control systems employ methods such as eddy current ranging, laser ranging, and temperature tracking. However, these methods suffer from large ranging errors, unstable signals, and an inability to accurately reflect the actual air gap. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a full-load visual air leakage control system and a fully enclosed static seal.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A full-load visual air leakage control system includes a signal acquisition system, a fan-shaped plate lifting device, and a control system. The signal acquisition system includes an aperture lens, a bracket, a front-end lighting lamp, and an industrial camera. The industrial camera transmits video signals to a DCS or to a local image display control system for image processing and outputs control signals. The sector plate lifting device includes a geared motor, a drive disc, a screw jack, and two booms. The drive disc controls the forward and reverse rotation of the geared motor, which drives the screw jack to rise or fall, thereby controlling the rise or fall of the air preheater sector plate through the two booms. The control system includes an electrical control cabinet, which contains an industrial computer, analog input devices, display and setting devices, a temperature gauge, relays, and a control box.

[0007] Preferably, the control box is equipped with a micro-break switch, a contactor, a relay, and a terminal block.

[0008] Preferably, the aperture lens has an operating temperature range of -30 to 500°C and an adjustable focal length of 3.6 to 18 mm.

[0009] Preferably, the aperture lens is mounted on a bracket, aligned with the gap between the fan-shaped plate and the rotor, and the focal length is adjusted.

[0010] Preferably, the industrial camera is mounted behind the aperture lens, a cooling air is added inside the bracket, and a front-end light is mounted at the front of the bracket to illuminate the gap position.

[0011] The present invention also proposes a fully enclosed static seal, including a sector plate and a static seal installed around the sector plate.

[0012] Preferably, the static seal is composed of an expansion joint.

[0013] Preferably, the expansion joint is made of stainless steel.

[0014] The beneficial effects of the full-load visual air leakage control system and the fully enclosed static seal described in this invention are as follows: 1. The aperture lens can adapt to the harsh environment of high temperature and dust in the air preheater. The equipment is easy to maintain and requires little maintenance, which ensures the effectiveness of the system's air leakage rate control and long-term stable operation.

[0015] 2. This system can also be installed at the cold end, solving the problem that traditional air leakage control systems cannot control the air leakage rate under low load conditions.

[0016] 3. The main / auxiliary motor current and temperature signals of the unit have excellent stability, and an overcurrent regulation and protection function has been added to ensure a very high automatic start-up rate of the air leakage system under any operating condition, ensuring the safe and reliable operation of the system.

[0017] 4. The fan-shaped plate lifting device has a reasonable and perfect design structure, with excellent mechanical transmission and sealing performance. The two motors serve as backups for each other, and manual operation can be achieved, effectively avoiding the occurrence of operational accidents.

[0018] 5. A control strategy employing both position control and temperature control modes as backups is adopted. Static and dynamic error processing of the acquired signal data by the industrial control computer reduces regional control errors, ultimately effectively controlling the air leakage rate.

[0019] 6. It has accurate tracking distance, high reliability, is easy to install and maintain, and is suitable for long-term continuous operation.

[0020] The fully enclosed static seal can completely block ash from entering the fan-shaped plate channel, which can completely solve the problem of ash accumulation in the fan-shaped plate. At the same time, it can ensure that the air leakage control system can safely and stably lift and press down the fan-shaped plate. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a full-load visual air leakage control system proposed in this invention; Figure 2 This is a schematic diagram of the structure of the fan-shaped plate lifting device of the full-load visual air leakage control system proposed in this invention; Figure 3 This is a schematic diagram of the electrical control cabinet of a full-load visual air leakage control system proposed in this invention; Figure 4 This is a schematic diagram of the control box of a full-load visual air leakage control system proposed in this invention; Figure 5 This is a schematic diagram of a fully enclosed static seal proposed in this invention; Figure 6 This is a schematic diagram of a fully enclosed static seal sector plate and expansion joint proposed in this invention; Figure 7 This is a sector control logic diagram of a full-load visual air leakage control system proposed in this invention.

[0022] In the diagram: 1. Sector-shaped plate lifting device; 2. Signal acquisition system; 3. Electrical control cabinet; 4. Control box; 5. Sector-shaped plate; 6. Static seal; 7. Expansion joint. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Reference Figures 1-7 A full-load visual air leakage control system includes a signal acquisition system 2, a fan-shaped plate lifting device 1, and a control system. The signal acquisition system 2 includes an aperture lens, a bracket, a front-end lighting lamp, and an industrial camera. The industrial camera transmits video signals to a DCS or to a local image display control system for image processing and outputs control signals. The sector plate lifting device 1 includes a geared motor, a drive disc, a screw jack, and two booms. The drive disc controls the forward and reverse rotation of the geared motor, which drives the screw jack to rise or fall, thereby controlling the rise or fall of the air preheater sector plate through the two booms. The control system includes an electrical control cabinet 3, which houses an industrial computer, analog input devices, display and setting devices, a temperature gauge, relays, and a control box 4. Each sector plate of the preheater has its own independent control subsystem, capable of both automatic and manual operation. Operation, status display, and numerical display are all completed via a touchscreen.

[0025] In this embodiment, the control box 4 is equipped with a micro-break switch, a contactor, a relay, and a terminal block.

[0026] In this embodiment, the aperture lens operates in a temperature range of -30 to 500°C, and the focal length is adjustable from 3.6 to 18 mm.

[0027] In this embodiment, an aperture lens is mounted on a bracket, aligned with the gap between the sector plate and the rotor, and its focus is adjusted. An industrial camera is mounted behind the aperture lens. Cooling air is blown into the bracket, and a front-end light is mounted at the front of the bracket, illuminating the gap. The industrial camera outputs a video signal to a DCS or local industrial control computer to display the image and calculate the gap distance. The gap range is set, and three signals—lift, lower, and stop—are output to the local lifting mechanism to maintain the sealing gap within the optimal set range. The system's automatic control program can detect and track rotor thermal deformation in real time, maintaining the gap between the sector plate and the rotor radial sealing plate at the set value of 4mm when hot.

[0028] Industrial cameras, also known as video cameras, have advantages over traditional consumer cameras (video cameras), such as high image stability, high transmission capability, and high anti-interference capability. Most industrial cameras on the market are based on CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) chips.

[0029] CCDs are currently the most commonly used image sensors in machine vision. They integrate photoelectric conversion, charge storage, charge transfer, and signal readout, making them typical solid-state imaging devices. A key characteristic of CCDs is that they use electric charge as a signal, unlike other devices that use current or voltage. These imaging devices form charge packets through photoelectric conversion, which are then transferred, amplified, and output as image signals under the action of driving pulses. A typical CCD camera consists of an optical lens, a timing and synchronization signal generator, a vertical driver, and analog / digital signal processing circuitry. As a functional device, CCDs offer advantages over vacuum tubes, including no burn-in, no hysteresis, low-voltage operation, and low power consumption.

[0030] The development of CMOS image sensors first appeared in the early 1970s. In the early 1990s, with the advancement of Very Large Scale Integration (VLSI) manufacturing technology, CMOS image sensors experienced rapid development. A CMOS image sensor integrates a photosensitive element array, image signal amplifier, signal readout circuit, analog-to-digital converter, image signal processor, and controller onto a single chip, and also possesses the advantage of programmable random access to local pixels. CMOS image sensors, with their excellent integration, low power consumption, high-speed transmission, and wide dynamic range, have been widely used in high-resolution and high-speed applications. Industrial cameras are a key component in machine vision systems; their most fundamental function is to convert light signals into ordered electrical signals. Here, distance measurement using images is employed.

[0031] Because industrial cameras are electronic devices, they are not heat-resistant. To operate in high-temperature environments, they need to be equipped with aperture lenses. The aperture lens extends into the high-temperature environment, while the industrial camera remains outside. The aperture lens parameters are as follows: Size: 1 / 3" Interface method: C / CS Focal length f=3.6-18mm Aperture (F): 2.5-360 Angle of view (horizontal): 43~81° External dimensions (mm): ￠20×110 Weight (g): 118 Operating temperature: -30~500℃ Features: Manual zoom, manual aperture.

[0032] Control strategy (1) Position control Using a visual industrial camera as the primary signal source, the gap signal detected by the camera between the bottom surface of the sector plate and the rotor angle steel is used to drive the sector plate lifting device to perform phased actions through an industrial control computer program, thereby adjusting the position of the sector plate and completing the automatic tracking and control of the sealing gap.

[0033] (2) Temperature control Using temperature control as the second signal source, the industrial control computer collects the temperature data of the air and flue gas at the hot and cold ends of the air preheater. Combined with the unit load signal and the rotor main motor current signal, the program judges and controls the actuator to adjust the position of the sector plate, thereby completing the automatic control of the sealing gap. This is the basic principle of temperature control.

[0034] (3) Measures to ensure safe operation The displacement sensor under the sector plate sends a 4-20mA analog signal, corresponding to the actual displacement value of the sector plate, which is then sent to the air leakage control cabinet. The rotor speed is monitored; when the rotor speed slows down or stops, a signal is sent to the programmable controller to urgently lift the sector plate and activate the alarm relay. Additionally, the DCS can monitor the rotor motor current; when the current value exceeds the rated value, the DCS sends a signal to the air leakage control cabinet, which then sends a signal to lift the sector plate. The logic diagram is as follows: Figure 7 .

[0035] This embodiment also proposes a fully enclosed static seal, including a sector plate 5 and a static seal 6 installed around the sector plate 5.

[0036] In this embodiment, the static seal 6 is composed of an expansion joint 7, one end of which is welded to the sector plate and the other end is welded to the truss plate surface.

[0037] In this embodiment, the expansion joint 7 is made of stainless steel.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A full-load visual air leakage control system, characterized in that, It includes a signal acquisition system (2), a fan-shaped plate lifting device (1) and a control system. The signal acquisition system (2) includes an aperture lens, a bracket, a front-end lighting lamp and an industrial camera. The industrial camera transmits video signals to the DCS or to the local image display control system for image processing and outputs control signals. The sector plate lifting device (1) includes a geared motor, a drive disc, a screw jack, and two booms. The drive disc controls the forward and reverse rotation of the geared motor, which drives the screw jack to rise or fall, thereby controlling the rise or fall of the air preheater sector plate through the two booms. The control system includes an electrical control cabinet (3), which contains an industrial computer, an analog input device, a display setting device, a temperature meter, a relay, and a control box (4).

2. The full-load visual air leakage control system according to claim 1, characterized in that, The control box (4) is equipped with a micro-break switch, a contactor, a relay, and a terminal block.

3. The full-load visual air leakage control system according to claim 2, characterized in that, The aperture lens operates in a temperature range of -30 to 500°C and has an adjustable focal length of 3.6 to 18 mm.

4. The full-load visual air leakage control system according to claim 3, characterized in that, The aperture lens is mounted on the bracket, aligned with the gap between the fan-shaped plate and the rotor, and the focal length is adjusted.

5. The full-load visual air leakage control system according to claim 4, characterized in that, The industrial camera is mounted behind the aperture lens, with a cooling air supply inside the bracket, and a front-end light installed at the front of the bracket, illuminating the gap.

6. A fully enclosed static seal, characterized in that, Includes a sector plate (5) and a static seal (6) installed around the sector plate (5).

7. The fully enclosed static seal according to claim 6, characterized in that, The static seal (6) is composed of an expansion joint (7).

8. A fully enclosed static seal according to claim 7, characterized in that, The expansion joint (7) is made of stainless steel.

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